Based on his experimental studies, Libet claims that voluntary actions are initiated by unconscious brain activities well before intentions or decisions to act are consciously experienced by people. This account conflicts with our common-sense conception of human agency, in which people consciously and intentionally exert volitions or acts of will to initiate voluntary actions. This paper offers an alternative interpretation of Libet's experiment. The cause of the intentional acts performed by the subjects in Libet's (...) experiment should not be exclusively attributed to special cerebral processes; conscious intentions formed at the beginning of the experiment, when the subjects received experimental instructions, must be taken into account. In addition, what the subjects were required to report was not a conscious intention or decision to act that conventionally figures in the etiology of voluntary action, but rather a perceived effective urge to move induced by specific experimental instructions. According to the alternative interpretation, the most suitable mental term correlated with the specific brain activity that precedes conscious, self-initiated voluntary bodily movements is volition. This account is supported by recent theories of function of the supplementary motor area . Therefore, the notion that we are the authors or originators of our own actions, which is fundamental to our common understanding of free will, moral responsibility and human dignity, can be preserved. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Commentary on “Free Will in the Light of Neuropsychiatry”Benjamin Libet (bio)Is Free Will Incompatible with Neuroscience?Sean Spence sets forth some interesting approaches to the issue of free will. His concepts are provocative and his marshalling of related quotations is informative.However, I shall argue with some of his crucial assumptions, in a way that affects the validity of some of Spence’s major conclusions. The latter are that (...) “conscious experience is always temporally postneural activity and thus... ‘caused’ not causal. Our ‘control’ is a sense which may be lost.... Our sense of agency is apparently illusory.”I have, of course, no quarrel with the view that even a fully voluntary act is initiated unconsciously (non-consciously). That condition was in fact demonstrated experimentally by us (Libet et al. 1983) when we found that cerebral neural activity (“readiness potential”) precedes the subject’s awareness of his/her intention or wish to act by at least 350 msec. This applied to fully self-initiated acts that occurred without “pre-planning” by the subject of when to move. (Incidentally, those finding have been replicated by others—see Keller and Heckhansen, 1990 with commentary thereon by Libet 1992, and Wong et al. 1988).However, we also found that conscious intention did precede that actual motor act by about 200 msec. That left open the potentiality for the conscious function to control the outcome of the process that was initiated in the brain unconsciously (see Libet 1985). We have all had the experience of consciously suppressing or vetoing the performance of an urge or intention to act. The 200 msec interval provides sufficient time in which the voluntary process could be stopped, before final activation of the motor area about 50 msec before the act. We were able to show that subjects could veto an act in the 100–200 msec interval before the expected time for the action.Spence dismisses this free will potentiality in the control or veto of a voluntary process. He says: “It is flawed because the ‘decision’ (in consciousness) to act or not to act is itself the ‘result’ of preceding neural activity.” This argument is based on my own evidence that a period of up to 500 msec of cerebral activity is required to produce a conscious sensory experience (Libet 1993, for review).But conscious control of a process is not the same as becoming aware of the volitional intent (Libet 1985, 563–564). Control implies the imposing of a change, in this case after the appearance of the awareness of intention to act. Conscious control may not necessarily require the same neural “time-on” feature that precedes the appearance of awareness per se. There is presently [End Page 95] no directly applicable evidence against the appearance of a conscious control function without prior neural processes specific to its initiation.In short, one cannot cavalierly dismiss the possibility of a conscious free will function on the basis of a belief that such a control function must be itself initiated unconsciously by prior specific neural processes. The argument that conscious free will control is simply a useful delusion must still be regarded as a philosophical belief, not a scientifically demonstrated proposition.Spence goes on to suggest that “Consciousness is necessary for purposeful (intentional) action but it is not the initiator.” But if Spence is consistent in his view that all conscious functions are preceded by specific neural activities that initiate the function, then his putative role for consciousness would have been itself initiated unconsciously. How, then, would consciousness be “performing (purposeful, intentional) actions with subtlety and invention” if it is simply an after-effect of the responsible cerebral process? It would appear that Spence is postulating an active role for consciousness in directing the course of neural activities carrying out purposeful, intentional actions. That is the kind of potentiality I was suggesting must be kept open, but one that Spence dismissed elsewhere as “flawed.”On a technical point: The Grey Walter experiment is cited as evidence for postulated effects of timing, in the “illusion” of self-initiation of an act. However, that experimental result was simply due to the fact that the motor cortex initiates the command... (shrink)

This article examines three aspects of the problem of understanding Benjamin Libet’s idea of conscious will causally interacting with certain neural activities involved in generating overt bodily movements. The first is to grasp the notion of cause involved, and we suggest a definition. The second is to form an idea of by what neural structure(s) and mechanism(s) a conscious will may control the motor activation. We discuss the possibility that the acts of control have (...) to do with levels of supplementary motor area activity and with the activation of populations of excitatory and inhibitory interneurons. The third aspect is to conceive of the main features of Libet’s proposed conscious mental field (CMF). We consider both an ontological and an epistemological interpretation of the CMF being nonphysical. In an attempt to refute the idea that Libet’s dualist mind–brain interactionism would violate the law of conservation of energy, we suggest that a CMF may alter the probability of the ion-channel gating by influencing structures of a size to which quantum mechanics needs to be applied. We argue that given the suggested definition of cause, and given the epistemological interpretation of the CMF being nonphysical, nothing would necessarily rule out that an element of a CMF, conscious will, may causally interact with neural activities in the brain. This defense of the idea of conscious will being causally efficacious has a bearing not only on the understanding of the mind–brain relation but also on the free will debate. (shrink)

The belief in free will has been frequently challenged since Benjamin Libet published his famous experiment in 1983. Although Libet’s experiment is highly dependent upon subjective reports, no study has been conducted that focused on a first-person or introspective perspective of the task. We took a neurophenomenological approach in an N = 1 study providing reliable and valid measures of the first-person perspective in conjunction with brain dynamics. We found that a larger readiness potential is attributable to more (...) frequent occurrences of self-initiated movements during negative deflections of the slow cortical potentials . These negative deflections occur in parallel with an inner impulse reported by an expert meditator which may in turn lead to a voluntary act. We demonstrate in this proof-of-principle approach that the first-person perspective obtained by an expert meditator in conjunction with neural signal analysis can contribute to our understanding of the neural underpinnings of voluntary acts. (shrink)

Voluntary acts are preceded by electrophysiological (RPs). With spontaneous acts involving no preplanning, the main negative RP shift begins at about200 ms. Control experiments, in which a skin stimulus was timed (S), helped evaluate each subject's error in reporting the clock times for awareness of any perceived event.

Proceeding from the observation by Ryle that I cannot prepare myself for the next thought that I am going to think, I argue that conscious acts cannot control my bodily motions or thoughts. This position is not compatible with indeterminism. I also argue that consciousness represents the irreducible and multi-modal output of the behavioral control system sensors necessary for the control of human behavior demonstrated by Marken . My analysis supports one experimental result obtained by Libet, Gleason, Wright, (...) and Pearl , namely, that the initiation of a "voluntary act" is an unconscious cerebral process. I conclude that the following are not realizable: "mental intentions" acting on the supplementary motor area as postulated by Eccles and Robinson , and "veto," a conscious abort of a motor act after subjects reported "wanting to act" . These two items would seem to be amenable to test by studies similar to or refinements of Libet's. (shrink)

The anterior cingulate cortex (ACC)has been identified as part of a supervisoryattentional network for selecting alternativemotor programs in response to top-down corticalprocessing, particularly in situationsinvolving conflicting cognitive tasks.Bilateral lesions to the ACC may be causallyassociated with akinetic mutism, where patientsare unable to voluntarily initiate responses.The clinical and neuroanatomical evidence forthis presumed causal association is examined atlength. However, given the many reciprocalprojections between cerebral, motor, limbic andparalimbic structures within the executivesupervisory network, the association ofvoluntary behavior with a particular structure(the (...) ACC) is highly controversial and thereforepremature at this time. Also considered is theclaim that our subjective sense of voluntarycontrol and free will is simply due toour not having conscious access to theunderlying neural computations that precede our decisions and actions. On thecontrary, the distinction between voluntary and involuntary thoughts and actions mayrather be a matter of temporal and directionallag between parallel computations in differentneural areas. Finally, with reference toDennett, there is an extended discussion ofwhether patients with akinetic mutism are (i) conscious automata, (ii) non-intentional systems, and (iii) in azombie-like state. The relevance of (i)–(iii) for the cognitive neuroscientificliterature is then briefly addressed. (shrink)

This review summarizes recent experiments on neuronal mechanisms underlying goal-directed behaviour. We investigated two basic processes, the internally triggered initiation of movement and the processing of reward information. Single neurons in the striatum were activated a few seconds before self-initiated movements in the absence of external triggering stimuli. Similar activations were observed in the closely connected cortical supplementary motor area, suggesting that these activations might evolve through build up in fronto-basal ganglia loops. They may relate (...) to intentional states directed at movements and their outcomes. As a second result, neurons in the striatum were activated in relation to the expectation and detection of rewards. Since rewards constitute important goals of behaviour, these activitations might reflect the evaluation of outcome before the behavioural reaction is executed. Thus neurons in the basal ganglia are involved in individual components of goal-directed behaviour. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Response to the CommentariesSean A. SpenceIn “Free Will in the Light of Neuropsychiatry,” I have attempted to present an argument from the perspective of materialist neuroscience, pushing the latter to its logical conclusion: that if the human nervous system is consistent in its properties, then the only place for “free will” is in the non-conscious processes which underpin conscious awareness. This argument I have based (...) on two supports: the “spatial” and the “temporal” (Spence, 1995).I have contended that the sense of freedom may be lost from certain actions, thereby implying that “freedom” is a sensory process distinct from action. This might be conceptualized as having a distinct functional distribution within the nervous system (a spatial distinction). I have also argued that conscious awareness of events occurs at a finite delay, the period of “neuronal adequacy,” after those events themselves. The point here is that neurochemical events giving rise to phenomenology are likely to require a period of time (no matter how short) for their genesis. The process is “on line” before we perceive it (a temporal distinction). Thus the “freedom to act,” a motor process, is necessarily non-conscious at the point of initiation.I am grateful to Frith, Libet and Stephens for their comments. In the most part our disagreements are likely to be those of emphasis, perhaps compounded by my uses of the term “free will.”I have no major disagreement with Frith’s comments. I would, however, emphasize that it is likely that the Bereitschaftspotential, or readiness potential, does tell us something regarding intended actions. It is, for example, absent prior to the involuntary movements seen in Tourette’s syndrome (Obeso et al. 1982), and reduced in akinetic patients with Parkinson’s disease (Dick et al. 1989) or medial frontal lobe lesions (Deecke et al. 1987). The latter groups have difficulty initiating intended, internally generated, actions.With regard to the suspicion of dualism in my diagrams, the point is well taken, but I am attempting to describe a functional distinction, the precise coordinates of which remain obscure. It may well be that “consciousness” occupies no fixed location but is an activity temporarily co-extant with that association cortex (or cortices) subserving the sensory modality (or modalities) experienced phenomenologically (see Bottini et al. 1995).I have based much of my “temporal” argument on Libet’s work, and I am grateful for his response. Nevertheless, I am still of the opinion that there is a central inconsistency with his argument that conscious control exerts a veto on acts which is somehow free of material constraints. [Indeed he states that he has “no quarrel with the view that even a fully voluntary act is initiated unconsciously (non-consciously)”.] Whereas I can [End Page 99] not prove that this power of veto does not evade neurochemical processes, or that it somehow acts instantaneously and independently, with no origin in unconscious processing, I can say that I have restricted myself to arguing within a materialist perspective, with the aim of “pushing it” to its extreme. The free will which Libet retains in consciousness is one which is unique, and unconstrained by materialism. It is dualism in disguise!Stephens implies that there is a non-argument regarding consciousness acting as an initiator of events. The suggestion is that no one would argue this. Yet this is Libet’s argument. It cannot be disproved, but it is clearly (internally) inconsistent with Libet’s own impressive body of work.As for the role of consciousness in action, I have, I think, invoked a position similar to that adopted by Stephens; that consciousness is more a sensory state, allowing awareness of actions, and their consequences, and perhaps thereby facilitating the function of non-conscious initiators. It is clearly necessary for the performance of the “higher” acts which we equate with human nature, but it is not sufficient. (Indeed many of the most creative insights have “emerged” into consciousness [see Boden, 1992].) The man with a paralyzed arm may wish for his arm to move but to no avail. Over time function may slowly reappear. But if his lesion is such that he is unaware of his impairment (anosognosia), then his prognosis may... (shrink)

I propose an Aristotelian approach to agent causation that is consistent with the hypothesis of strong emergence. This approach motivates a wider ontology than materialism by maintaining (1) that the agent is generated by the brain without being reducible to it on grounds of the unity of experience and (2) that the agent possesses (formal) causal power to affect (i.e., mold, sculpt, or organize) the brain on grounds of agent-directed neuroplasticity. After providing recent empirical evidence for the strong (...) emergence of the agent, I then articulate and analyze a dominant objection to agent causation discussed in neuroscience, which is based upon the observation of the readiness potential (or RP) in the brain. In this context, the RP refers to unconscious neuronal events (in the supplementary motor area) that precede the formation of a (proximal) conscious intention to act. So it appears as if the train of neuronal events has left the depot before the agent can act. In response to this objection, I argue (a) that even if one were to grant that the RP precedes the formation of a conscious intention, it would not follow (on both logical and empirical grounds) that there is no conscious agent causation; and (b) that the objection disappears when one takes into account distal versus proximal intentions. (shrink)

Brindley proposed that we initially generate movements , under higher cerebral control. As the movement is practiced, the cerebellum learns to link within itself the context in which the movement is made to the lower level movement generators. Marr and Albus proposed that the linkage is established by a special input from the inferior olive, which plays upon an input-output element within the cerebellum during the period of the learning. When the linkage is complete, the occurrence of (...) the context (represented by a certain input to the cerebellum) will trigger (through the cerebellum) the appropriate motor response. The movement is distinguished from the conscious movement by its now being automatic, rapid, and stereotyped. The idea is still controversial, but has been supported by a variety of animal studies and, as reviewed here, is consistent with the results of a number of human PET and ablation studies. I have added to the idea of context-response linkage what I think is another important variable: novel combinations of downstream elements. With regard to the motor system and the muscles, this could explain how varied combinations of muscles may become active in precise time-amplitude specifications so as to produce coordinated movements appropriate to specific contexts. In this target article, I have further extended this idea to the premotor parts of the brain and their role in cognition. These areas receive influences from the cerebellum; they are active both in planning movements that are to be executed and in thinking about movements that are not to be executed. From recent evidence, the cerebellar output extends even to what has been characterized as the ultimate frontal planning area, the cortex, area 46. The cerebellum thus may be involved in context-response linkage, and response combination even at these higher levels. The implication would be that, through practice, an experiential context would automatically evoke a certain mental action plan. The plan would be in the realm of thought, and could lead to execution. The specific cerebellar contribution would be one of the context linkage and the shaping of the response, through trial and error learning. The prefrontal and premotor areas could still plan without the help of the cerebellum, but not so automatically, rapidly, stereotypically, so precisely linked to context, or so free of error. Nor would their activities improve optimally with mental practice. (shrink)

I have taken an experimental approach to this question. Freely voluntary acts are preceded by a specific electrical change in the brain that begins 550 ms before the act. Human subjects became aware of intention to act 350-400 ms after RP starts, but 200 ms. before the motor act. The volitional process is therefore initiated unconsciously. But the conscious function could still control the outcome; it can veto the act. Free will is therefore (...) not excluded. These findings put constraints on views of how free will may operate; it would not initiate a voluntary act but it could control performance of the act. The findings also affect views of guilt and responsibility. But the deeper question still remains: Are freely voluntary acts subject to macro-deterministic laws or can they appear without such constraints, non-determined by natural laws and ‘truly free'? I shall present an experimentalist view about these fundamental philosophical opposites. (shrink)

I have taken an experimental approach to this question. Freely voluntary acts are preceded by a specific electrical change in the brain that begins 550 ms before the act. Human subjects became aware of intention to act 350-400 ms after RP starts, but 200 ms. before the motor act. The volitional process is therefore initiated unconsciously. But the conscious function could still control the outcome; it can veto the act. Free will is therefore (...) not excluded. These findings put constraints on views of how free will may operate; it would not initiate a voluntary act but it could control performance of the act. The findings also affect views of guilt and responsibility. But the deeper question still remains: Are freely voluntary acts subject to macro-deterministic laws or can they appear without such constraints, non-determined by natural laws and ‘truly free'? I shall present an experimentalist view about these fundamental philosophical opposites. (shrink)

The conscious feeling of exercising ‘free-will’ is fundamental to our sense of self. However, in some psychopathological conditions actions may be experienced as involuntary or unwilled. We have used suggestion in hypnosis to create the experience of involuntariness in normal participants. We compared a voluntary finger movement, a passive movement and a voluntary movement suggested by hypnosis to be ‘involuntary.’ Hypnosis itself had no effect on the subjective experience of voluntariness associated with willed (...) movements and passive movements or on time estimations of their occurrence. However, subjective time estimates of a hypnotically-suggested, ‘involuntary’ finger movement were more similar to those for passive movements than for voluntary movements. The experience of anomalous control is qualitatively and quantitatively different from the normal conscious experience of a similar act produced intentionally. The experience of anomalous control may be produced either by pathology, or, in our case, by suggestion. (shrink)

BackgroundTranscranial direct current stimulation targeting the primary motor hand area may induce lasting shifts in corticospinal excitability, but after-effects show substantial inter-individual variability. Functional magnetic resonance imaging can probe after-effects of TDCS on regional neural activity on a whole-brain level.ObjectiveUsing a double-blinded cross-over design, we investigated whether the individual change in corticospinal excitability after TDCS of M1-HAND is associated with changes in task-related regional activity in cortical motor areas.MethodsSeventeen healthy volunteers received 20 min of real or (...) sham TDCS on separate days in randomized order. Real and sham TDCS used the classic bipolar set-up with the anode placed over right M1-HAND. Before and after each TDCS session, we recorded motor evoked potentials from the relaxed left first dorsal interosseus muscle after single-pulse transcranial magnetic stimulation of left M1-HAND and performed whole-brain fMRI at 3 Tesla while participants completed a visuomotor tracking task with their left hand. We also assessed the difference in MEP latency when applying anterior-posterior and latero-medial TMS pulses to the precentral hand knob.ResultsReal TDCS had no consistent aftereffects on mean MEP amplitude, task-related activity or motor performance. Individual changes in MEP amplitude, measured directly after real TDCS showed a positive linear relationship with individual changes in task-related activity in the supplementary motor area and AP-LM MEP latency.ConclusionFunctional aftereffects of classical bipolar anodal TDCS of M1-HAND on the motor system vary substantially across individuals. Physiological features upstream from the primary motor cortex may determine how anodal TDCS changes corticospinal excitability. (shrink)

The typical approach to decoding speech from the brain (using brain-machine interfaces) is to decode low-level linguistic units (e.g. phonemes, syllables) from motor articulation areas (e.g. Premotor cortex) with the aim of assembling these low-level units into higher-level discourse. We propose that brain-to-speech decoding may benefit from adopting a functional view of language, which conceives of language as an instrumental tool for interacting with others' intentions in order to fulfil one's own intentions. This functional view (...) of language motivates adopting usability (i.e. the decoder's usefulness as a tool for achieving goals), in addition to decoding accuracy, as a criterion for assessing decoder performance. Decoders may achieve gains in usability by incorporating data about communicative situations and speaker intentions in order to generate and fill in speech act templates. We suggest that this intention-oriented, template-based, and functionally inspired view of brain-to-speech decoding may facilitate efforts to achieve naturalistic speech decoding. (shrink)

When Husserl discussed the phenomenology of willing, he concluded that the sole theoretical foundation of the intentionality of consciousness is insufficient to account for voluntary acts as they do not primarily represent their content as given entities, but instead create the willed during their performance. Nonetheless, Husserl did not suspend the theoretical foundation of intentionality, meaning that the theoretical concept of objectual intentionality juxtaposes a practical concept of performative intentionality. Recent results from the field of robot-assisted gait rehabilitation (...) provided experimental findings that may clarify this relationship, to the effect that the foundational structure of consciousness builds upon a heterarchical model of objectual and performative intentionality. A combination of phenomenological interview results, neural motor control, the functional design of the robot, and clinical data qualifies gait initiation as a non-objectifying act that creates its intentional object (i.e., the willed movement). In sum, the experimental findings support Husserl’s proposal of a genuine practical or performative intentionality that points to a heterarchical understanding of the relationship between representational and performative foundations of action consciousness. (shrink)

Posterior parietal cortex has traditionally been considered to be a sensory association area in which higher-order processing and intermodal integration of incoming sensory information occurs. In this paper, evidence from clinical reports and from lesion and behavioral-electrophysiological experiments using monkeys is reviewed and discussed in relation to the overall functional organization of posterior parietal association cortex, and particularly with respect to a proposed posterior parietal mechanism concerned with the initiation and control of certain classes of eye (...) and limb movements. Preliminary data from studies of the effects of posterior parietal lesions on oculomotor control in monkeys are reported.The behavioral effects of lesions of posterior parietal cortex in monkeys have been found to be similar to those which follow analogous damage of the minor hemisphere in humans, while behavioral-electrophysiological experiments have disclosed classes of neurons in this area which have functional properties closely related to the behavioral acts that are disrupted by lesions of the area. On the basis of current data from these areas of study, it is proposed that the sensory association model of posterior parietal function is inadequate to account for the complexities of the present evidence. Instead, it now appears that many diverse neural mechanisms are locatedin partin parietal cortex, that some of these mechanisms are involved in sensory processing and perceptual functions, but that others participate in motor control, and that still others are involved in attentional, motivational, or emotional processes. It is further proposed that the elementary units of these various neural mechanisms are distributed within posterior parietal cortex according to the columnar hypothesis of Mountcastle. (shrink)

The meaning and significance of Benjamin Libet’s studies on the timing of conscious will have been widely discussed, especially by those wishing to draw sceptical conclusions about conscious agency and free will. However, certain important correctives for thinking about mental states and processes undermine the apparent simplicity and logic of Libet’s data. The appropriateness, relevance and ecological validity of Libet’s methods are further undermined by considerations of how we ought to characterise intentional actions, conscious (...) class='Hi'>intention, and what it means to act with conscious intent. Recent extensions of Libet’s paradigm using fMRI and decision-based tasks suffer from similar limitations. The result is that these sorts of laboratory studies of isolated, trivial, decontextualized bodily movements, in a context of extended (conscious) intentional experimental participation and cooperation, are of dubious and potentially misleading relevance to the study of agency. (shrink)

1. Introduction The readiness potential was found to precede voluntary acts by about half a second or more (Kornhuber & Deecke, 1965). Kornhuber (1984) discussed the readiness potential in terms of volition, arguing that it is not the manifestation of an attentional processes. Libet discussed it in relation to consciousness and to free will (Libet et al. 1983a; 1983b; Libet, 1985, 1992, 1993). Libet asked the following questions. Are voluntary acts initiated by a conscious (...) decision to act? Are the physiological facts compatible with the belief that free will determines our voluntary acts? What is the role of consciousness in voluntary action? In this paper I will discuss these questions and the answers that Libet gave to them. (shrink)

Animals search for food and shelter by locomotion through time and space. The elemental step is the action-perception cycle, which has three steps. In the first step a volley of action potentials initiated by an act of search triggers the formation of a macroscopic wave packet that constitutes the memory of the stimulus. The wave packet is filtered and sent to the entorhinal cortex, where it is combined with wave packets from all sensory systems. This triggers the second (...) step forming a unified memory that is passed through the hippocampal formation where it is assigned a place in the life-long memory of the subject. In the third step the output of the entorhinal cortex triggers the formation of a global wave packet that synchronizes the oscillatory activity of most of not all of the cerebral cortex. This shared oscillation caries a pattern of amplitude modulation, that can be observed non-invasively from the scalp EEG of human volunteers perceiving the stimulus and correlated with the stimulus. The same dendritic electric currents that drive the output of the brains of the wave packet drive the observed EEG signs. Therefore I postulate that the global wave packet, the third step in the cycle requiring only 0.2 seconds expresses the memory of the global accommodation that initiates the next action-perception cycle. Some unspecified fraction of the AM pattern is available to me the observer, and some other unspecified fraction of the total activity in the subject who is expected to respond to the stimulus. There is reason to hope that these fractions will coincide often enough to support refinements in techniques for extending these correlates of consciousness. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}. (shrink)

The problem of free will lies at the heart of modern scientific studies of consciousness. An influential series of experiments by Libet has suggested that conscious intentions arise as a result of brain activity. This contrasts with traditional concepts of free will, in which the mind controls the body. A more recent study by Haggard and Eimer has further examined the relation between intention and brain processes, concluding that conscious awareness of intention (...) is linked to the choice or selection of a specific action, and not to the earliest initiation of action processes. The exchange of views in this paper further explores the relation between conscious intention and brain activity. (shrink)

Spontaneous actions are preceded by brain signals that may sometimes be detected hundreds of milliseconds in advance of a subject's conscious intention to act. These signals have been claimed to reflect prior unconscious decisions, raising doubts about the causal role of conscious will. Murakami et al. (2014. Nat Neurosci 17: 1574–1582) have recently argued for a different interpretation. During a task in which rats spontaneously decided when to abort waiting, the authors recorded neurons in the (...) secondary motor cortex. The neural activity and relationship to action timing was parsimoniously explained using an integration-to-bound model, similar to those widely used to account for evidence-based decisions. In this model, the brain accumulates spontaneously occurring inputs voting for or against an action, but only commits to act once a certain threshold is crossed. The model explains how spontaneous decisions can be forecast (partially predicted) by neurons that reflect either the input or output of the integrator. It therefore presents an explicit hypothesis capable of rejecting the claim that such predictive signals imply unconscious decisions. We suggest that these results can inform the current debate on free will but must be considered with caution. (shrink)

Intentional action involves both a series of neural events in the motor areas of the brain, and also a distinctive conscious experience that ''I'' am the author of the action. This paper investigates some possible ways in which these neural and phenomenal events may be related. Recent models of motor prediction are relevant to the conscious experience of action as well as to its neural control. Such models depend critically on matching the actual consequences of (...) a movement against its internally predicted effects. However, it remains unclear whether our conscious experience of action depends on a precise matching process, or a retrospective inference that ''I'' must have been responsible for a particular event. We report an experiment in which normal subjects judged the perceived time of either intentional actions, involuntary movements, or subsequent effects (auditory tones) of these. We found that the subject's intention to produce the auditory tone produced an intentional binding between the perceived times of the subject's action and the tone. However, if the intention was interrupted by an imposed involuntary movement, followed by the identical tone, no such binding occurred. The phenomenology of intentional action requires an appropriate predictive link between intentions and effects, rather than a retrospective inference that ''I'' caused the effect. (shrink)

ObjectiveThe effects and possible mechanisms of cerebellar high-frequency repetitive transcranial magnetic stimulation on swallowing-related neural networks were studied using resting-state functional magnetic resonance imaging.MethodA total of 23 healthy volunteers were recruited, and 19 healthy volunteers were finally included for the statistical analysis. Before stimulation, the cerebellar hemisphere dominant for swallowing was determined by the single-pulse TMS. The cerebellar representation of the suprahyoid muscles of this hemisphere was selected as the target for stimulation with 10 Hz rTMS, 100% resting motor (...) threshold, and 250 pulses, with every 1 s of stimulation followed by an interval of 9 s. The motor evoked potential amplitude of the suprahyoid muscles in the bilateral cerebral cortex was measured before and after stimulation to evaluate the cortical excitability. Forty-eight hours after elution, rTMS was reapplied on the dominant cerebellar representation of the suprahyoid muscles with the same stimulation parameters. Rs-fMRI was performed before and after stimulation to observe the changes in amplitude of low-frequency fluctuation and regional homology at 0.01–0.08 Hz, 0.01–0.027 Hz, and 0.027–0.073 Hz.ResultsAfter cerebellar high-frequency rTMS, MEP recorded from swallowing-related bilateral cerebral cortex was increased. The results of rs-fMRI showed that at 0.01–0.08 Hz, ALFF was increased at the pons, right cerebellum, and medulla and decreased at the left temporal lobe, and ReHo was decreased at the left insular lobe, right temporal lobe, and corpus callosum. At 0.01–0.027 Hz, ALFF was decreased at the left temporal lobe, and ReHo was decreased at the right temporal lobe, left putamen, and left supplementary motor area.ConclusionRepetitive transcranial magnetic stimulation of the swallowing cortex in the dominant cerebellar hemisphere increased the bilateral cerebral swallowing cortex excitability and enhanced pontine, bulbar, and cerebellar spontaneous neural activity, suggesting that unilateral high-frequency stimulation of the cerebellum can excite both brainstem and cortical swallowing centers. These findings all provide favorable support for the application of cerebellar rTMS in the clinical practice. (shrink)

Free will, which is dealt with under the title of "acts of the servants" in the Kalām literature, is one of the fundamental issues of the science of Kalām. Benjamin Libet's famous experiment, which he conducted in order to seek an answer to the question of free will, caused the free will debates to move to the field of neuroscience. The logic of Libet's experiment is to compare the neural activity in the brain with the (...) moment when a person is conscious while performing a voluntary act. In Libet's subjects, it was observed that brain activity in the decision-making process started at the moment of unconsciousness. The results of this experiment have long been interpreted in neuroscience as showing that free will is an illusion. Although Libet claimed that conscious intention creates a veto effect by stopping the action at the last moment, recent studies have shown that Libet's veto solution for free will does not work. The most vocal critics of the implications of the Libet experiment from the beginning have generally been philosophers. In this article, the criticisms of the Libet experiments by names such as Marcel Brass, Alfred Mele, and Peter Ulric Tse are presented. However, especially in recent years, neuroscientist Aaron Schurger's experimental and mathematical reinterpretation of the concept of readiness potential, which is key for Libet, and his proposal of an alternative model are mentioned. The article discusses Schurger's claim that the readiness potential may not actually reflect a brain that is ready. According to Schurger, the readiness potential is just random fluctuations that already exist in the brain and is not the sole cause of decisions. In fact, it has been argued that the readiness potential is related to neural noise in the brain rather than to the decision-making process. Thanks to Schurger's critique and the new model, it became clear that the Libet experiment did not rule out free will. But it does not constitute a proof of free will either. While the subject remains a mystery, it is unthinkable for Kalām to remain aloof from these debates. The article also touches upon the views of the Jabriyya, Ash'ariyya, Maturidiyya and Mu'tazilah in Kalām regarding the acts of the servants and questions what the Libet experiment can mean for these schools. Accordingly, while Jabriyya, with its deterministic view, may correspond to an erroneous interpretation of the Libet experiment, Mutazila may be the school that will have the most difficulty in explaining the Libet experiment. As a result, it seems that the views that consider both human agency and God's creation in voluntary acts are the most accurate. Moreover, despite the lack of a clear explanation of the theory of kasb in the Ash'ariyya, the Maturidiyya's assertion that the juz'i will is uncreated and that two influences affect voluntary acts suggests that this school provides the most solid foundation for free will. In order for such discussions to proceed on a healthy basis, it is very important to follow multidisciplinary methods. In addition, as much as Kalāmists should approach scientific studies seriously, it is important that they do not adopt a completely submissive attitude in the face of scientific claims, and that they learn the relevant critiques from experts in the field. Only in this way, we believe that the scientific inferences to be made will be based on a solid ground and that Kalāmists can make serious contributions to the solution. (shrink)

The goal of this article is to review some aspects of brain anatomy and neurophysiology that are important for consciousness, and which hopefully may be of benefit to philosophers investigating the conscious mind. Taking as an initial point of reference the distinction between “the hard problem” and “the weak problems” of consciousness, we shall concentrate on questions pertaining to the second of these. A putative “consciousness system” in the brain will be presented, paying special attention to (...) diffuse projection systems. The “center of gravity” will be brain connectivity, since consciousness must, critically, be dependent on coherent activity and timing. “Detectors” of synchronicity and coincidence, like NMDA receptors, also necessarily play a role here. To be conscious, we do not need an entire brain. While even large hemispherectomies need not unequivocally affect consciousness, far smaller brain-stem lesions may be devastating in this regard. Even so, the recent discovery by Matthew F. Glasser et al. of 180 separate areas in the human brain cortex is intriguing from a teleological perspective, as it is quite unthinkable that any of them could be “redundant. (shrink)

Benjamin Libet has argued that electrophysiological signs of cortical movement preparation are present before people report having made a conscious decision to move, and that these signs constitute evidence that voluntary movements are initiated unconsciously. This controversial conclusion depends critically on the assumption that the electrophysiological signs recorded by Libet, Gleason, Wright, and Pearl are associated only with preparation for movement. We tested that assumption by comparing the electrophysiological signs before a decision to move with signs (...) present before a decision not to move. There was no evidence of stronger electrophysiological signs before a decision to move than before a decision not to move, so these signs clearly are not specific to movement preparation. We conclude that Libet’s results do not provide evidence that voluntary movements are initiated unconsciously. (shrink)

The goal of this article is to review some aspects of brain anatomy and neurophysiology that are important for consciousness, and which hopefully may be of benefit to philosophers investigating the conscious mind. Taking as an initial point of reference the distinction between “the hard problem” and “the weak problems” of consciousness, we shall concentrate on questions pertaining to the second of these. A putative “consciousness system” in the brain will be presented, paying special attention to (...) diffuse projection systems. The “center of gravity” will be brain connectivity, since consciousness must, critically, be dependent on coherent activity and timing. “Detectors” of synchronicity and coincidence, like NMDA receptors, also necessarily play a role here. To be conscious, we do not need an entire brain. While even large hemispherectomies need not unequivocally affect consciousness, far smaller brain-stem lesions may be devastating in this regard. Even so, the recent discovery by Matthew F. Glasser et al. of 180 separate areas in the human brain cortex is intriguing from a teleological perspective, as it is quite unthinkable that any of them could be “redundant. (shrink)

The chief goal of Velmans' article is to find a way to solve the problem of how conscious experience could have bodily effects. I shall discuss his treatment of this below. First, I would like to deal with Velmans' treatment of my own studies of volition and free will in relation to brain processes. Unconscious Initiation and Conscious Veto of Freely Voluntary Acts Velmans appropriately refers to our experimental study that found that onset (...) of an electrically observable cerebral process preceded the appearance of the subject's awareness of the conscious wish to act, by at least 350 msec. That indicated that the volitional process is initiated unconsciously. Velmans uses the term preconscious instead of unconscious. But, in fact, subjects have no reportable awareness or intuitive feeling that the brain has started a process before their conscious wish/urge to act appears. Unconscious initiation of the voluntary process appeared to mean that conscious free will could not actually 'tell' the brain to begin its preparation to carry out a voluntary act. (shrink)

This essay, as will become obvious, owes a huge debt to Mark Kelman, particularly to his article “Interpretative Construction in the Substantive Criminal Law.” That debt is one of both concept and content. There is rich irony in my aping Kelman's deconstructionist enterprise, for I do not share his enthusiasm for either the “insights” or the political agenda of the Critical Legal Studies movement. I do not believe that either the law in general or the criminal law in (...) particular is radically indeterminate, rife with internal contradictions, or an expression of the interests of a dominant economic class. And although, like Kelman, I believe that the freedom/determinism, act/character, and rule/principle dichotomies must ultimately be dealt with in order to have a completely satisfactory account of criminal law, I also believe that these dichotomies loom just as large in other areas of law and in normative theory generally. They are problems for Crits as well as for liberal-legalists. In any event, my intentions in undertaking this deconstructionist enterprise are modestly reformist, not revolutionary. I do not intend to shift any paradigms, but to work with well-established ones. I will assume that criminal law seeks to accomplish some blend of retributive response to and deterrence of culpable choices, choices to defy moral norms that are also legal norms. I will also assume that a culpable choice is one that reflects negatively on the values held by the chooser. Beyond these quite modest assumptions, I need not and will not venture in this paper, realizing, of course, that much has and can be written about the proper aims of punishment and the proper account of culpability. (shrink)

Libet, Gleason, Wright, & Pearl (1983) asked participants to report the moment at which they freely decided to initiate a pre-specified movement, based on the position of a red marker on a clock. Using event-related potentials (ERPs), Libet found that the subjective feeling of deciding to perform a voluntary action came after the onset of the motor “readiness potential,” RP). This counterintuitive conclusion poses a challenge for the philosophical notion of free will. Faced with these (...) findings, Libet (1985) proposed that conscious volitional control might operate as a selector and a controller of volitional processes rather than as an initiator of them. (shrink)

The aim of this paper is to challenge the claim that the neural activity commonly referred to as 'readiness potential' constitutes evidence for the unconscious initiation of action. Although I accept that such neural activity seriously challenges the commonly held view that one's sense of volition is causally efficacious, I nevertheless contend that much of our everyday engagement with the world is consciously initiated. Thus, a distinction is made between awareness and what the awareness is of: the latter constituting (...) the conscious decision to act in accordance with one's goal, or what I have termed intentional project. Initiation of an action in accordance with one's intentional project grounds the action in meaning, something that would be lacking in an exclusively unconscious decision to act. (shrink)

Focus of attention is one of the most influential factors facilitating motor performance. Previous evidence supports that the external focus strategy, which directs attention to movement outcomes, is associated with better motor performance than the internal focus strategy, which directs attention to body movements. However, recent studies have reported that the EF strategy is not effective for some individuals. Furthermore, neuroimaging studies have demonstrated that the frontal and parietal areas characterize individual optimal attentional strategies for motor (...) tasks. However, whether the sensory cortices are also functionally related to individual optimal attentional strategy remains unclear. Therefore, the present study examined whether an individual’s sensory processing ability would reflect the optimal attentional strategy. To address this point, we explored the relationship between responses in the early sensory cortex and individuals’ optimal attentional strategy by recording steady-state somatosensory evoked potentials and steady-state visual evoked potentials. Twenty-six healthy young participants first performed a motor learning task with reaching movements under IF and EF conditions. Of the total sample, 12 individuals showed higher after-effects under the IF condition than the EF condition, whereas the remaining individuals showed the opposite trend. Subsequently, we measured SSSEP from bilateral primary somatosensory cortices while presenting vibrotactile stimuli and measured SSVEP from bilateral primary visual cortices while presenting checkerboard visual stimuli. The degree of increasing SSSEP response when the individuals in the IF-dominant group directed attention to vibrotactile stimuli was significantly more potent than those in the EF-dominant individuals. By contrast, the individuals in the EF-dominant group showed a significantly larger SSVEP increase while they directed attention to visual stimuli compared with the IF-dominant individuals. Furthermore, a significant correlation was observed such that individuals with more robust IF dominance showed more pronounced SSSEP attention modulation. These results suggest that the early sensory areas have crucial brain dynamics to characterize an individual’s optimal attentional strategy during motor tasks. The response characteristics may reflect the individual sensory processing ability, such as control of priority to the sensory inputs. Considering individual cognitive traits based on the suitable attentional strategy could enhance adaptability in motor tasks. (shrink)

Capacity of conscious agents to perform genuine choices among future alternatives is a prerequisite for moral responsibility. Determinism that pervades classical physics, however, forbids free will, undermines the foundations of ethics, and precludes meaningful quantification of personal biases. To resolve that impasse, we utilize the characteristic indeterminism of quantum physics and derive a quantitative measure for the amount of free will manifested by the brain cortical network. The interaction between the central nervous system and the surrounding (...) environment is shown to perform a quantum measurement upon the neural constituents, which actualize a single measurement outcome selected from the resulting quantum probability distribution. Inherent biases in the quantum propensities for alternative physical outcomes provide varying amounts of free will, which can be quantified with the expected information gain from learning the actual course of action chosen by the nervous system. For example, neuronal electric spikes evoke deterministic synaptic vesicle release in the synapses of sensory or somatomotor pathways, with no free will manifested. In cortical synapses, however, vesicle release is triggered indeterministically with probability of 0.35 per spike. This grants the brain cortex, with its over 100 trillion synapses, an amount of free will exceeding 96 terabytes per second. Although reliable deterministic transmission of sensory or somatomotor information ensures robust adaptation of animals to their physical environment, unpredictability of behavioral responses initiated by decisions made by the brain cortex is evolutionary advantageous for avoiding predators. Thus, free will may have a survival value and could be optimized through natural selection. (shrink)

S. Pockett and G. Gomes discuss a possible bias in the method by which Libet's subjects estimated the time at which they became aware of their intent to move their hands. The bias, caused by sensory delay processing the clock information, would be sufficient to alter Trevena and Miller's conclusions regarding the timing of the lateralized readiness potential. I show that the flash-lag effect would compensate for that bias. In the last part of my commentary I note that the other (...) target articles do not examine the most interesting aspect of Libet's unfashionable views on free will. I point out that Libet's views are less strange than they at first appear to be. (shrink)

Can one be fooled into believing that one intended an action that one in fact did not intend? Past experimental paradigms have demonstrated that participants, when provided with false perceptual feedback about their actions, can be fooled into misperceiving the nature of their intended motor act. However, because veridical proprioceptive/perceptual feedback limits the extent to which participants can be fooled, few studies have been able to answer our question and induce the illusion to intend. In a novel paradigm addressing (...) this question, participants were instructed to move a line on the computer screen by use of a phony brain–computer interface. Line movements were actually controlled by computer program. Demonstrating the illusion to intend, participants reported more intentions to move the line when it moved frequently than when it moved infrequently. Consistent with ideomotor theory, the finding illuminates the intimate liaisons among ideomotor processing, the sense of agency, and action production. (shrink)

This thesis explores the possibility of theoretically conceiving consciousness as an activity of the brain. Objections, based on the concept of qualia, to the identification of consciousness with a brain activity are refuted. Phenomenal consciousness is identified with access-consciousness. Consciousness is conceived as a higher order processing of informational states of the brain. The state of consciousness represents an integration of prior nonconscious states. Libet’s research on the timing of conscious experience is reviewed and analyzed. His (...) hypothesis of backward referral is rejected. Since specific brain activity (the readiness potential) precedes the conscious intention, the implications of this fact on the concepts of volition and free will are discussed. Non-deliberate voluntary acts are performed without a prior consciousness of the intention to perform them. Conversely, the decision to perform a deliberate act is influenced by consciousness of the intention. Free will is viewed as compatible with the causal determination of mental processes. The theory is successfully applied to the different contents of consciousness: consciousness of perceptions, of bodily sensations, of actions, of memories, of ideas, of thoughts, of language, of affective states, of beliefs, of desires, of oneself and consciousness of being conscious. The relation between the theory of consciousness and psychoanalysis is also explored. Psychoanalysis is seen as compatible with the proposed theory, which is able to enlighten some aspects of the process of becoming conscious in psychoanalytic treatment. The general approach is interdisciplinary : the theory must take into account constraints derived from philosophy, neurophysiology, psychology, neuropsychology, etc. Consciousness is conceived, not as a property of some mental states, but as a specific higher-order activity, based on lower-order nonconscious activities. (shrink)

The neural correlates of rapid eye movements (REMs) in sleep are extraordinarily robust; including REM-locked activation in the retrosplenial cortex, the supplementary eye field and areas overlapping cholinergic basal nucleus. The phenomenology of REMs speaks to the notion that perceptual experience in both sleep and wakefulness is a constructive process – in which we generate predictions of sensory inputs and then test those predictions through actively sampling the sensorium with eye movements. On this view, REMs during sleep may (...) index an internalized active sampling or ‘scanning’ of self-generated visual constructs that are not constrained by visual input. If this view is correct, it renders REMs an ideal probe to study consciousness as “an exclusively internal affair” (Metzinger 2009). In other words, REMs offer a probe of active inference – in the sense of predictive coding – when the brain is isolated from the sensorium in virtue of the natural blockade of sensory input during REM sleep. REMs are temporally precise events that enable powerful inferences based on timeseries analyses. As a natural, task-free probe, [REMs] could be used in non-compliant subjects, including infants and animals. In short, REM constitutes a promising probe to study the ontogenetic and phylogenetic development of consciousness and perhaps its abnormal development in schizophrenia and autism, which have been considered in terms of aberrant predictive coding. (shrink)

Illusory kinesthetic sensation was influenced by motor imagery of the wrist following tendon vibration. The imagery and the illusion conditions commonly activated the contralateral cingulate motor area, supplementary motor area, dorsal premotor cortex, and ipsilateral cerebellum. This supports the notion that motor imagery is a mental rehearsal of movement, during which expected kinesthetic sensation is emulated by recruiting multiple motor areas, commonly activated by pure kinesthesia.

Wegner (2002) fails to (1) distinguish conscious will and voluntariness; (2) account for everyday willed acts; and (3) individuate thoughts and acts. Wegner incorrectly implies that (4) we experience acts as willed only when they are caused by unwilled thoughts; (5) thoughts are never true causes of actions; and (6) we experience ourselves as first performing mental acts which then cause our intentional actions.

Intentions are commonly conceived of as discrete mental states that are the direct cause of actions. In the last several decades, neuroscientists have taken up the project of finding the neural implementation of intentions, and a number of areas have been posited as implementing these states. We argue, however, that the processes underlying action initiation and control are considerably more dynamic and context sensitive than the concept of intention can allow for. Therefore, adopting the notion of ‘intention’ (...) in neuroscientific explanations can easily lead to misinterpretation of the data, and can negatively influence investigation into the neural correlates of intentional action.We suggest reinterpreting the mechanisms underlying intentional action, and we will discuss the elements that such a reinterpretation needs to account for. (shrink)

In his interesting commentary, Joshua Shepherd raises two points—one related to epistemology, the other to ethics—about our article on human cerebral organoids.1 2 From the epistemological standpoint, he calls into question the need for a theory of consciousness. A theory of consciousness, for him, is not necessary because of the lack of consensus about the very nature of consciousness. Shepherd suggests that ‘given widespread disagreement, applying a theory of consciousness may not be helpful when attempting to diagnose the presence of (...) consciousness in cerebral organoids’. In Shepherd’s view, it would be better to transfer ‘concepts already under development in work on the presence and structure of consciousness in difficult marginal cases involving traumatic brain injury’.2 We could not agree more on this last point; detecting a minimal capacity for consciousness in the brain of comatose patients is a very similar challenge to inferring the presence of consciousness in cerebral organoids. Every day, as a by-product of saving many lives, intensive care medicine artificially produces thousands of brains that may remain isolated, split or fragmented; in the worst case, cortical islands, or an archipelago of islands, may survive while being disconnected from the outside world. Can these islands host some form of consciousness? That is, does it feel like anything to be a large piece of human cortex? Addressing this difficult question requires the development of general, objective brain-based indices of consciousness that are independent of sensory processing, executive functions and motor outputs.3 Consider, for example, a patient showing reflexive spontaneous behaviour, no response to command and no ability to communicate. In her brain, afferent pathways are damaged, thereby impairing the recruitment of cortical areas in response to sensory stimulation; basal ganglia, as well as other frontal structures supporting executive functions, are impaired. However, resting metabolism and significant electroencephalography …. (shrink)