The ability to perform movements is vital for our daily life. Our actions are embedded in a complex environment where we need to deal efficiently in the face of unforeseen events. Neural oscillations play an important role in basic sensorimotor processes related to the execution and preparation of movements. In this review, I will describe the state of the art regarding the role of motor gamma oscillations in the control of movements. Experimental evidence from electrophysiological studies has shown that (...) motor gamma oscillations accomplish a range of functions in motor control beyond merely signaling the execution of movements. However, these additional aspects associated with motor gamma oscillation remain to be fully clarified. Future work on different spatial, temporal and spectral scales is required to further understand the implications of gamma oscillations in motor control. (shrink)

Theories of the representation of specific kinetic and spatiotem-poral features of movement range from the explicit assertion that temporal aspects of movement are not represented to the idea that they are represented and that they have neurophysiological correlates. Jeannerod's thesis is that mental and visual images have common mechanisms and that there is a link between the image to move and the mechanisms involved with movement. The target article takes the position that certain parameters are coded in (...) motor representations but that the duration of an action is not one of them. This position is based on the work of Gottlieb et al. and of Decety et al.. Both these studies are worth considering in detail. In Note 1, Jeannerod suggests that: “in time-constrained tasks subjects control the amplitude parameter of force impulses, whereas in spatially constrained tasks the duration of the force impulse is affected by accuracy demands.” This is not exactly correct. Excitation pulse intensity is modulated both in tasks that require spatial and those that require temporal accuracy. Excitation pulse duration is modulated for changes in movement distance and inertial load. If subjects are required to be very accurate spatially, they will move at less than maximum speed for a given distance and this is achieved by lower levels of excitation intensity. (shrink)

Three issues related to Feldman and Levin's treatment of biological variability are discussed. We question the usefulness of the indirect component of δλ. We suggest that trade-offs between speed and accuracy in aimed movements support identification of δλ, rather than λ, as a control variable. We take issue with the authors' proposal for resolving redundancy in multi-joint movements, given recent data.

Dienes & Perner argue that volitional control in artificial grammar learning is best understood in terms of the distinction between implicit and explicit knowledge representations. We maintain that direct, explicit access to knowledge organised in a hierarchy of implicitness/explicitness is neither necessary nor sufficient to explain volitional control. People can invoke volitional control when their knowledge is implicit, as in the case of artificial grammar learning, and they can invoke volitional control when (...) any part of their knowledge representation is implicit, as can be seen by examining “feeling of knowing” phenomena. (shrink)

A theory is presented to explain how accurate, single-joint movements are controlled. The theory applies to movements across different distances, with different inertial loads, toward targets of different widths over a wide range of experimentally manipulated velocities. The theory is based on three propositions. (1) Movements are planned according to “strategies” of which there are at least two: a speed-insensitive (SI) and a speed-sensitive (SS) one. (2) These strategies can be equated with sets of rules for performing diverse movement (...) tasks. The choice between SI and SS depends on whether movement speed and/or movement time (and hence appropriate muscle forces) must be constrained to meet task requirements. (3) The electromyogram can be interpreted as a low-pass filtered version of the controlling signal to the motoneuron pools. This controlling signal can be modelled as a rectangular excitation pulse in which modulation occurs in either pulse amplitude or pulse width. Movements to different distances and with loads are controlled by the SI strategy, which modulates pulse width. Movements in which speed must be explicitly regulated are controlled by the SS strategy, which modulates pulse amplitude. The distinction between the two movement strategies reconciles many apparent conflicts in the motor control literature. (shrink)

Some individuals have a neurogenetic vulnerability to developing strong facilitation of ingestive movements by learned configurations of biosocial stimuli. Condemning food as addictive is mere polemic, ignoring the contextualised sensory control of the mastication of each mouthful. To beat obesity, the least fattening of widely recognised eating patterns need to be measured and supported.

The current assessment of behaviors in the inventories to diagnose autism spectrum disorders (ASD) focus on observation and discrete categorizations. Behaviors require movements, yet measurements of physical movements are seldom included. Their inclusion however, could provide an objective characterization of behavior to help unveil interactions between the peripheral and the central nervous systems. Such interactions are critical for the development and maintenance of spontaneous autonomy, self-regulation and voluntary control. At present, current approaches cannot deal with the heterogeneous, dynamic and (...) stochastic nature of development. Accordingly, they leave no avenues for real-time or longitudinal assessments of change in a coping system continuously adapting and developing compensatory mechanisms. We offer a new unifying statistical framework to reveal re-afferent kinesthetic features of the individual with ASD. The new methodology is based on the non-stationary stochastic patterns of minute fluctuations (micro-movements) inherent to our natural actions. Such patterns of behavioral variability provide re-entrant sensory feedback contributing to the autonomous regulation and coordination of the motor output. From an early age, this feedback supports centrally driven volitional control and fluid, flexible transitions between intentional and spontaneous behaviors. We show that in ASD there is a disruption in the maturation of this form of proprioception. Despite this disturbance, each individual has unique adaptive compensatory capabilities that we can unveil and exploit to evoke faster and more accurate decisions. Measuring the kinesthetic re-afference in tandem with stimuli variations we can detect changes in their micro-movements indicative of a more predictive and reliable kinesthetic percept. Our methods address the heterogeneity of ASD with a personalized approach grounded in the inherent sensory-motor abilities that the individual has already developed. (shrink)

Visual feedback regulation during movement is not fully captured in Plamondon's kinematic theory. However, numerous studies indicate that visual response-produced feedback is a powerful determinant of performance and kinematic characteristics of target-directed movement.

In lieu of an abstract, here is a brief excerpt of the content:306 THE WILL AS WISH Hume's theory of action — that the will is the cause of voluntary action — is still one of the main accounts about the relationship of will and action in current discussion. In the following I will first show that Wittgenstein revived Hume's theory in his early philosophy. I will argue that wishing is taken as a model for willing in both Hume's and (...) the early Wittgenstein's theories. I am therefore speaking of a 'wish-theory of will'. In his middle and later philosophy, however, Wittgenstein presents a completely different point of view. He acknowledges the deep difference between wishing and willing. In willing, but not in wishing, we do have knowledge, namely we can predict our future voluntary actions. This knowledge is to be distinguished from our knowledge of future events in nature. I believe that the wish-model of willing can be regarded as 'philosophically confused' in Wittgenstein's sense: he who says that we cannot know what our future voluntary actions will be, is in fact only attacking our linguistic conventions regarding the meaning of 'will' or 'intention,' though he thinks he is defending an empirical claim. In conclusion it is claimed that the adherents of Hume's theory of action and also most of Wittgenstein's followers have not been aware of the consequences of Wittgenstein's conceptual criticism. So the discussion turns still (once again) around Hume's question: whether the relationship of willing and acting is a causal one or one "of logical compulsion. " [10.248.208.35] Project MUSE (2024-02-19 15:08 GMT) JHU Libraries 307 1. Pavid Hume's Theory of Action In An Enquiry Concerning Human Understanding, Sect. VII, Part I, Hume gives several arguments in favour of the thesis that, "like all other natural events," the influence of volition over the organs of the body can only be known by experience. His second argument here is from the comparison of voluntary with involuntary movements. He is arguing against the thesis that the relationship between the will and voluntary movement might be that of logical necessity. If that were the case, then by inspecting the cause we would be aware of a certain power producing the effect. But we are not conscious of such a power in distinguishing this relationship from the one between will and involuntary movements. So we can only conclude that in most cases, when we have willed certain (namely voluntary) movements, the movement has followed upon our will, and that we must 2 infer the necessity of this relationship. His first argument backs up the second: the relationship between will and voluntary movement, between soul and body, is a completely mysterious one: "were we empowered, by a secret wish, to remove mountains, or control the planets in their orbit: this extensive authority would not be more extraordinary, nor more beyond our comprehension." (E 65) Now, without wanting to milk too much out of this remark, I take it in fact to give Hume's model for his account of willing: If the influence of volition over the organs of the body in voluntary movement is known only by experience, volition is nothing but a wish. We normally would distinguish between wishing and willing in using 'wishing' where we at least believe that the wish will not come true. And this is just what follows from Hume's description 308 of the will: that we don't know and cannot know if the execution of the will will come true. An example is his distinction of voluntary and involuntary movement: if we don't know that our volition (of a voluntary movement) will come true, then will is perfectly equal in this respect to our wish (of an involuntary movement, or some other event). So Hume points to a man, suddenly struck with palsy in a leg, who wills to move his leg: Hume's volition is logically independent of its execution. But his denial of knowledge in will blurs the distinction between willing and wishing. I will argue that there is an epistemic difference between willing and wishing, in spite of the logical independence of both from what... (shrink)

In lieu of an abstract, here is a brief excerpt of the content:306 THE WILL AS WISH Hume's theory of action — that the will is the cause of voluntary action — is still one of the main accounts about the relationship of will and action in current discussion. In the following I will first show that Wittgenstein revived Hume's theory in his early philosophy. I will argue that wishing is taken as a model for willing in both Hume's and (...) the early Wittgenstein's theories. I am therefore speaking of a 'wish-theory of will'. In his middle and later philosophy, however, Wittgenstein presents a completely different point of view. He acknowledges the deep difference between wishing and willing. In willing, but not in wishing, we do have knowledge, namely we can predict our future voluntary actions. This knowledge is to be distinguished from our knowledge of future events in nature. I believe that the wish-model of willing can be regarded as 'philosophically confused' in Wittgenstein's sense: he who says that we cannot know what our future voluntary actions will be, is in fact only attacking our linguistic conventions regarding the meaning of 'will' or 'intention,' though he thinks he is defending an empirical claim. In conclusion it is claimed that the adherents of Hume's theory of action and also most of Wittgenstein's followers have not been aware of the consequences of Wittgenstein's conceptual criticism. So the discussion turns still (once again) around Hume's question: whether the relationship of willing and acting is a causal one or one "of logical compulsion. " [10.248.208.35] Project MUSE (2024-02-19 15:08 GMT) JHU Libraries 307 1. Pavid Hume's Theory of Action In An Enquiry Concerning Human Understanding, Sect. VII, Part I, Hume gives several arguments in favour of the thesis that, "like all other natural events," the influence of volition over the organs of the body can only be known by experience. His second argument here is from the comparison of voluntary with involuntary movements. He is arguing against the thesis that the relationship between the will and voluntary movement might be that of logical necessity. If that were the case, then by inspecting the cause we would be aware of a certain power producing the effect. But we are not conscious of such a power in distinguishing this relationship from the one between will and involuntary movements. So we can only conclude that in most cases, when we have willed certain (namely voluntary) movements, the movement has followed upon our will, and that we must 2 infer the necessity of this relationship. His first argument backs up the second: the relationship between will and voluntary movement, between soul and body, is a completely mysterious one: "were we empowered, by a secret wish, to remove mountains, or control the planets in their orbit: this extensive authority would not be more extraordinary, nor more beyond our comprehension." (E 65) Now, without wanting to milk too much out of this remark, I take it in fact to give Hume's model for his account of willing: If the influence of volition over the organs of the body in voluntary movement is known only by experience, volition is nothing but a wish. We normally would distinguish between wishing and willing in using 'wishing' where we at least believe that the wish will not come true. And this is just what follows from Hume's description 308 of the will: that we don't know and cannot know if the execution of the will will come true. An example is his distinction of voluntary and involuntary movement: if we don't know that our volition (of a voluntary movement) will come true, then will is perfectly equal in this respect to our wish (of an involuntary movement, or some other event). So Hume points to a man, suddenly struck with palsy in a leg, who wills to move his leg: Hume's volition is logically independent of its execution. But his denial of knowledge in will blurs the distinction between willing and wishing. I will argue that there is an epistemic difference between willing and wishing, in spite of the logical independence of both from what... (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)

Why do we run toward people we love, but only walk toward others? Why do people in New York seem to walk faster than other cities? Why do our eyes linger longer on things we value more? There is a link between how the brain assigns value to things, and how it controls our movements. This link is an ancient one, developed through shared neural circuits that on one hand teach us how to value things, and on the other hand (...) control the vigor with which we move. As a result, when there is damage to systems that signal reward, like dopamine and serotonin, that damage not only affects our mood and patterns of decision making, but how we move. In this book, we first ask why in principle evolution should have developed a shared system of control between valuation and vigor. We then focus on the neural basis of vigor, synthesizing results from experiments that have measured activity in various brain structures and neuromodulators, during tasks in which animals decide how patiently they should wait for reward, and how vigorously they should move to acquire it. Thus, the way we move unmasks one of our well-guarded secrets: how much we value the thing we are moving toward. (shrink)

The main issue addressed here concerns the central notion of a forward internal model, through which efficient control and planning are linked together and to the related online predictive error processing. The existence of such a model has strong implications in action production and may question Glover's model.

Features of gait are determined at multiple levels, from the selection of the gait itself (e.g. walk or run) through the specific parameters utilized (stride length, frequency, etc.) to the pattern of muscular excitation. The ultimate choices are neurally determined, but what is involved with that decision process? Human locomotion appears stereotyped not so much because the pattern is predetermined, but because these movement patterns are good solutions for providing movement utilizing the machinery available to the individual (the (...) legs and their requisite components). Under different circumstances the appropriate solution may differ broadly (different gait) or subtly (different parameters). Interpretation of the neural decision making process would benefit from understanding the influences that determine the selection of the appropriate solution in any set of circumstances, including that of normal conditions. In this review we survey an array of studies that point to energetic cost as a key input to the gait coordination system, and not just an outcome of the gait pattern implemented. We then use that information to rigorously define the construct proposed by Sparrow and Newell (1998) where the effects of environment, organism and task act as constraints determining the solution set available, and the coordination pattern is then implemented under a pressure for energetic economy. Environment is defined in terms of affordances based on the ecological psychology definition of the concept and organism is defined as classic morphology and physiology based capabilities. We rely on a novel conceptualization of task that recognizes that the task goal needs to be separated from the mechanisms that achieve the goal if the motivation behind the selection of the mechanism strategy is to be exposed and understood. This reformulation of the Sparrow and Newell construct is then linked to the proposed pressure for economy by considering it as an optimization problem, where the most readily selected gait strategy will be that which achieves the task goal at (or near) the energetic minimum. (shrink)

Dienes & Perner's analysis provides a clear theoretical justification for using a demonstration of volitional control as a criterion for conscious awareness. However, in memory tasks, the converse does not hold: A phenomenological awareness of a memory episode can arise involuntarily, even when the task does not require retrieval of the episode. The varying amounts of volitional retrieval required by different memory tasks need to be recognized.

This chapter focuses on the experimental practices and reasoning strategies employed in nineteenth century investigations on the causal origin of the phenomenon of Brownian movement. It argues that there was an extensive and sophisticated experimental work done on the phenomenon throughout the nineteenth century. Investigators followed as rigorously as possible the methodological standards of their time to make causal claims and advance causal explanations of Brownian movement. Two major methodological strategies were employed. The first was the experimental strategy (...) of varying the circumstances. Suspected causal factors were varied and the resulting effect on Brownian movement was studied. The main goal of this strategy was the identification of difference-making factors, i.e., factors having a causal influence on the phenomenon. The second was the so-called method of hypothesis. Rather than relying exclusively on the ability of experiments to identify difference-making factors, its proponents tried to show how the independently developed tenets of the new kinetic-molecular conception of matter provided a plausible causal explanation of Brownian movement. Each one of these methodological strategies had its distinctive practices and notions of control. None of these strategies could, on its own, establish molecular motion as the cause of Brownian movement. It was only the fruitful combination of the two strategies and of their accompanying practices and notions of control that led, at the end of the nineteenth century, to the recognition of molecular motion as the most probable cause of Brownian movement. (shrink)

Sensation of Movement explores the role of sensation in motor control, bodily self-recognition and sense of agency. The sensation of movement is dependent on a range of information received by the brain, from signalling in the peripheral sensory organs to the establishment of higher order goals. Through the integration of neuroscientific knowledge with psychological and philosophical perspectives, this book questions whether one type of information is more relevant for the ability to sense and control movement. (...) Addressing conscious sensations of movement, experimental designs and measures, and the possible functions of proprioceptive and kinaesthetic information in motor control and bodily cognition, the book advocates the integration of neuroscientific knowledge and philosophical perspectives. With an awareness of the diverse ideas and theories from these distinct fields, the book brings together leading researchers to bridge these divides and lay the groundwork for future research. -/- Contributors: Thor Grünbaum and Mark Schram Christensen Andreas Kalckert Myrto Mylopoulos Mads Jensen, Mia Dong, Mikkel C. Vinding, and Morten Overgaard Anne Kavounoudias Matthew R. Longo Hong Yu Wong. (shrink)

Stuttering is a disorder characterized by intermittent loss of volitional control of speech movements. This hypothesis and theory article focuses on the proposal that stuttering may be related to an impairment of the energy supply to neurons. Findings from electroencephalography, brain imaging, genetics, and biochemistry are reviewed: Analyses of the EEG spectra at rest have repeatedly reported reduced power in the beta band, which is compatible with indications of reduced metabolism. Studies of the absolute level of regional cerebral (...) blood flow show conflicting findings, with two studies reporting reduced rCBF in the frontal lobe, and two studies, based on a different method, reporting no group differences. This contradiction has not yet been resolved. The pattern of reduction in the studies reporting reduced rCBF corresponds to the regional pattern of the glycolytic index. High regional GI indicates high reliance on non-oxidative metabolism, i.e., glycolysis. Variants of the gene ARNT2 have been associated with stuttering. This gene is primarily expressed in the brain, with a pattern roughly corresponding to the pattern of regional GI. A central function of the ARNT2 protein is to act as one part of a sensor system indicating low levels of oxygen in brain tissue and to activate appropriate responses, including activation of glycolysis. It has been established that genes related to the functions of the lysosomes are implicated in some cases of stuttering. It is possible that these gene variants result in a reduced peak rate of energy supply to neurons. Lastly, there are indications of interactions between the metabolic system and the dopamine system: for example, it is known that acute hypoxia results in an elevated tonic level of dopamine in the synapses. Will mild chronic limitations of energy supply also result in elevated levels of dopamine? The indications of such interaction effects suggest that the metabolic theory of stuttering should be explored in parallel with the exploration of the dopaminergic theory. (shrink)

The processes underlying motor decision-making have recently caught considerable amount of scientific attention, focusing on the integration of empirical evidence from sensorimotor control research with psychological theories and computational models on decision-making. Empirical studies on motor decision-making suggest that the kinematics of goal-directed reaching movements are sensitive to the level of target uncertainty during movement planning. However, the source of uncertainty as a relevant factor influencing the process of motor decision-making has not been sufficiently considered, yet. In this (...) study, we test the assumption that the source of target uncertainty has an effect on motor decision-making, which can be proven by analyzing movement variability during the time course of movement execution. Ten healthy young adults performed three blocks with 66 trials of goal-directed reaching movements in each block, across which the source and level of reach target uncertainty at movement onset were manipulated (“no uncertainty”, “extrinsic uncertainty”, “intrinsic uncertainty”). Fingertip position of the right index finger was recorded using an optical motion tracking system. Standard kinematic measures (i.e. path length and movement duration) as well as variability of fingertip position across the time course of movement execution and at movement end were analyzed. In line with previous studies, we found that a high level of extrinsic target uncertainty leads to increased overall movement duration, which could be attributed to increased path length in this condition, as compared to intrinsic and no target uncertainty (all p <.001). Movement duration and path length did not show any differences between the latter two conditions. However, the time course analysis of movement variability revealed significant differences between these two conditions, with increased variability of fingertip position in the presence of intrinsic target uncertainty (Condition × Sampling point: p =.01), though considerably less than under high extrinsic target uncertainty (p ≤.001). These findings suggest that both the level and source of uncertainty have a significant effect on the processing of potential action plans during motor decision-making, which can be revealed through the analysis of the time course of movement variability at the end-effector level. (shrink)

Information about positions, from which differences in position are computed (as proposed in the vector-integration-to-endpoint model), provides a more plausible perceptual basis for the control of goal-directed arm movements than information about distance (as proposed in the kinematic model).