It is the central hypothesis of this paper that the mental states commonly referred to as altered states of consciousness are principally due to transient prefrontal cortex deregulation. Supportive evidence from psychological and neuroscientific studies of dreaming, endurance running, meditation, daydreaming, hypnosis, and various drug-induced states is presented and integrated. It is proposed that transient hypofrontality is the unifying feature of all altered states and that the phenomenological uniqueness of each state is the result of the differential viability of various (...) frontal circuits. Using an evolutionary approach, consciousness is conceptualized as hierarchically ordered cognitive function. Higher-order structures perform increasingly integrative functions and thus contribute more sophisticated content. Although this implies a holistic approach to consciousness, such a functional hierarchy localizes the most sophisticated layers of consciousness in the zenithal higher-order structure: the prefrontal cortex. The hallmark of altered states of consciousness is the subtle modification of behavioral and cognitive functions that are typically ascribed to the prefrontal cortex. The theoretical framework presented yields a number of testable hypotheses. (shrink)

This review considers a number of recent theories on the neural basis of consciousness, with particular attention to the theories of Bogen, Crick, Llinás, Newman, and Changeux. These theories allot different roles to various key brain areas, in particular the reticular and intralaminar nuclei of the thalamus and the cortex. Crick's hypothesis is that awareness is a function of reverberating corticothalamic loops and that the spotlight ofintramodalattention is controlled by the reticular nucleus of the thalamus. He also proposed different mechanisms (...) for attention and intention . The current review presents a new hypothesis, based on elements from these hypotheses, includingintermodalattention and olfaction and pain, which may pose problems for Crick's original theory. This work reviews the possible role in awareness and intermodal attention and intention of the cholinergic system in the basal forebrain and the tegmentum; the reticular, the intralaminar, and the dorsomedial thalamic nuclei; the raphe and locus coeruleus; the reticular formation; the ventral striatum and extended amygdala; insula cortex, and other selected cortical areas. Both clinical and basic research data are covered. The conclusion is reached that the brain may work by largely nonlinear parallel processing and much intramodal shifts of attention may be effected by intracortical, or multiple corticothalamic mechanisms . But this is constrained by the functional anatomy of the circuits concerned and waking “awareness” is modulated by the many “nonspecific” systems . But the principal agents for intermodal attention shifts, the “searchlight,” may be two key nuclei of the cholinergic system in the mesencephalon. Clinical loss of consciousness results from damage to these nuclei but not from damage to the cholinergic nucleus basalis of the basal forebrain. (shrink)

Neuroanatomy and neurophysiology are insufficient to specify function. Modeling is essential to elucidate function, but psychophysics is also required. An example is the cognitive and sensorimotor branches of the visual system: anatomy shows direct cross talk between the branches. Psychophysics in normal humans shows links from cognitive to sensorimotor, but the reverse link is excluded by visual illusions affecting the cognitive system but not the sensorimotor system.

Combinatorial network optimization appears to fit well as a model of brain structure: connections in the brain are a critically constrained resource, hence their deployment in a wide range of cases is finely optimized to “‘save wire". This review focuses on minimization of large-scale costs, such as total volume for mammal dendrite and axon arbors and total wirelength for positioning of connected neural components such as roundworm ganglia (and also mammal cortex areas). Phenomena of good optimization raise questions about mechanisms (...) for their achievement: the examples of optimized neuroanatomy here turn out to include candidates for some of the most complex biological structures known to be derivable purely from simple physical energy minimization processes. Part of the functional role of such fine-tuned wiring optimization may be as a compact strategy for generating self-organizing complex neuroanatomical.. (shrink)

Although emotion is closely associated with motivation, and interacts with perception, cognition, and action, many conceptualizations still treat emotion as separate from these domains. Here, a comparative/evolutionary anatomy framework is presented to motivate the idea that long-range, distributed circuits involving the midbrain, thalamus, and forebrain are central to emotional processing. It is proposed that emotion can be understood in terms of large-scale network interactions spanning the neuroaxis that form “functionally integrated systems.” At the broadest level, the argument is made that (...) we need to move beyond a Newtonian view of causation to one involving complex systems where bidirectional influences and nonlinearities abound. Therefore, understanding interactions between subsystems and signal integration becomes central to unraveling the organization of the emotional brain. (shrink)

Major changes took place during the last quarter of the nineteenth century in the ways that the brain tissue was maintained, manipulated and studied, and, consequently, in the ways that its structure, functions and pathologies were seen and represented in neurological literature. The paper exemplifies these changes by comparing German neuroanatomy in the 1860s and early 1870s with the turn-of-the-century view of the brain . It argues for the crucial importance of a method—serial sectioning—to the emergence of the new (...) view of the brain. Serial sectioning in turn owes its existence to the new techniques in staining and sectioning that were introduced in the 1870s and 1880s. In particular, the paper highlights the role of a cutting device, the microtome, in enabling serial sectioning and in thereby contributing to the emergence of a new view of the brain. (shrink)

In this chapter, we aimed at further characterizing the functional neuroanatomy of the human rapid eye movement (REM) sleep at the population level. We carried out a meta-analysis of a large dataset of positron emission tomography (PET) scans acquired during wakefulness, slow wave sleep and REM sleep, and focused especially on the brain areas in which the activity diminishes during REM sleep. Results show that quiescent regions are confined to the inferior and middle frontal cortex and to the (...) inferior parietal lobule. Providing a plausible explanation for some of the features of dream reports, these findings may help in refining the concepts, which try to account for human cognition during REM sleep. In particular, we discuss the significance of these results to explain the alteration in executive processes, episodic memory retrieval and self representation during REM sleep dreaming as well as the incorporation of external stimuli into the dream narrative. (shrink)

Despite technological and interpretative advances, the non-invasive modalities used for pre-surgical evaluation of patients with drug-resistant epilepsy, fail to generate a concordant anatomo-electroclinical hypothesis for the location of the seizure onset zone in many patients. This requires chronic monitoring with intracranial electroencephalography, which facilitates better localization of the seizure onset zone, and allows evaluation of the functional significance of cortical regions-of-interest by electrical stimulation mapping. There are two principal modalities for intracranial EEG, namely subdural electrodes and stereotactic depth electrodes. (...) Although ESM is considered the gold standard for functional mapping with subdural electrodes, there have been concerns about its utility with stereo-EEG. This is mainly because subdural electrodes allow contiguous sampling of the dorsolateral convexity of cerebral hemispheres, and permit delineation of the extent of eloquent functional areas on the cortical surface. Stereo-EEG, while having relatively sparse sampling on the cortical surface, offers the ability to access the depth of sulci, mesial and basal surfaces of cerebral hemispheres, and deep structures such as the insula, which are largely inaccessible to subdural electrodes. As stereo-EEG is increasingly the preferred modality for intracranial monitoring, we find it opportune to summarize the literature for ESM with stereo-EEG in this narrative review. Emerging evidence shows that ESM for defining functional neuroanatomy is feasible with stereo-EEG, but probably requires a different approach for interpretation and clinical decision making compared to ESM with subdural electrodes. We have also compared ESM with stereo-EEG and subdural electrodes, for current thresholds required to evoke desired functional responses vs. unwanted after-discharges. In this regard, there is preliminary evidence that ESM with stereo-EEG may be safer than ESM with subdural grids. Finally, we have highlighted important unanswered clinical and scientific questions for ESM with stereo-EEG in the hope to encourage future research and collaborative efforts. (shrink)

This paper samples the large body of neuroscientific evidence suggesting that each mental function takes place within specific neural structures. For instance, vision appears to occur in the visual cortex, motor control in the motor cortex, spatial memory in the hippocampus, and cognitive control in the prefrontal cortex. Evidence comes from neuroanatomy, neurophysiology, neurochemistry, brain stimulation, neuroimaging, lesion studies, and behavioral genetics. If mental functions take place within neural structures, mental functions cannot survive brain death. Therefore, there is no (...) mental life after brain death. -/- 1. The Neural Localization of Mental Functions - 1.1 Perception and Motor Control - 1.2 Memory - 1.3 Emotion - 1.4 Language - 1.5 Thinking - 1.6 Attention and Consciousness - 1.7 Spirituality -- 2. Objections - 2.1 Linguistic Dualism - 2.2 Mere Correlation - 2.3 Neural Plasticity - 2.4 Intentionality - 2.5 Phenomenal Consciousness - 2.6 Subjectivity - 2.7 Self-Knowledge - 2.8 Free Will - 2.9 Are We Just Indulging in Physicalistic Wishful Thinking? -- 3. Conclusion -- Appendix: Physicalism and the Afterlife. (shrink)

A new view of the functional role of the left anterior cortex in language use is proposed. The experimental record indicates that most human linguistic abilities are not localized in this region. In particular, most of syntax (long thought to be there) is not located in Broca's area and its vicinity (operculum, insula, and subjacent white matter). This cerebral region, implicated in Broca's aphasia, does have a role in syntactic processing, but a highly specific one: It is the neural (...) home to receptive mechanisms involved in the computation of the relation between transformationally moved phrasal constituents and their extraction sites (in line with the Trace-Deletion Hypothesis). It is also involved in the construction of higher parts of the syntactic tree in speech production. By contrast, basic combinatorial capacities necessary for language processing – for example, structure-building operations, lexical insertion – are not supported by the neural tissue of this cerebral region, nor is lexical or combinatorial semantics. The dense body of empirical evidence supporting this restrictive view comes mainly from several angles on lesion studies of syntax in agrammatic Broca's aphasia. Five empirical arguments are presented: experiments in sentence comprehension, cross-linguistic considerations (where aphasia findings from several language types are pooled and scrutinized comparatively), grammaticality and plausibility judgments, real-time processing of complex sentences, and rehabilitation. Also discussed are recent results from functional neuroimaging and from structured observations on speech production of Broca's aphasics. Syntactic abilities are nonetheless distinct from other cognitive skills and are represented entirely and exclusively in the left cerebral hemisphere. Although more widespread in the left hemisphere than previously thought, they are clearly distinct from other human combinatorial and intellectual abilities. The neurological record (based on functional imaging, split-brain and right-hemisphere-damaged patients, as well as patients suffering from a breakdown of mathematical skills) indicates that language is a distinct, modularly organized neurological entity. Combinatorial aspects of the language faculty reside in the human left cerebral hemisphere, but only the transformational component (or algorithms that implement it in use) is located in and around Broca's area. Key Words: agrammatism; aphasia; Broca's area; cerebral localization; dyscalculia; functional neuroanatomy; grammatical transformation; modularity; neuroimaging; syntax; trace deletion. (shrink)

Any attempt to elucidate the nature and mechanism of passivity phenomena, i.e., experiences that one’s conscious actions or thoughts have not been ‘willed’ by oneself, requires an integrative philosophical–neurobiological approach. The model proposed here adopts some fundamental positions that have long been advocated by philosophers and theoretical psychologists and have now found support from functional neuroanatomy. First, we experience our actions not from the standpoint of the executive but through the perception of its effects. Second, the ‘self’ is (...) not an agent of behaviour. Third, behaviour is energised and integrated by basic drives . Fourth, the view that the experience of an acting self is related to drive reduction associated with voluntary actions is perhaps less well developed. The model thus proposes that passivity phenomena are actions that are induced by the perception of salient events but that are not integrated with or conducive to the overall motivational state of the organism. It has been suggested that, following the perception of salient events, competition arises between automatic response tendencies seeking expression. The prefrontal cortex appears to play an important role not only in determining which events are to be perceived but also which of the corresponding response dispositions is to be selected and actualised in overt behaviour. Thus, action selection is the outcome of competition between response tendencies in the context of prefrontal biasing signals that represent drives and strivings for goals. Action selection may be uncoupled from drives and strivings as a result of a lowering of the threshold for action selection—as is suggested to be the case in schizophrenic passivity phenomena—or due to disconnection from prefrontal regions—as may be the case in the alien limb syndrome. (shrink)

Although deductive reasoning is a closed system, one's beliefs about the world can influence validity judgements. To understand the associated functional neuroanatomy of this belief-bias we studied 14 volunteers using event-related fMRI, as they performed reasoning tasks under neutral, facilitatory and inhibitory belief conditions. We found evidence for the engagement of a left temporal lobe system during belief-based reasoning and a bilateral parietal lobe system during belief-neutral reasoning. Activation of right lateral prefrontal cortex was evident when subjects inhibited (...) a prepotent response associated with belief-bias and correctly completed a logical task, a finding consistent with its putative role in cognitive monitoring. By contrast, when logical reasoning was overcome by belief-bias, there was engagement of ventral medial prefrontal cortex, a region implicated in affective processing. This latter involvement suggests that belief-bias effects in reasoning may be mediated through an influence of emotional processes on reasoning. (shrink)

While philosophers have, for centuries, pondered upon the relation between mind and brain, neuroscientists have only recently been able to explore the connection analytically — to peer inside the black box. This ability stems from recent advances in technology and emerging neuroimaging modalities. It is now possible not only to produce remarkably detailed images of the brain’s structure (i.e. anatomical imaging) but also to capture images of the physiology associated with mental processes (i.e. functional imaging). We are able to (...) see how specific regions of the brain ‘light up’ when activities such as reading this book are performed, and how our neurons and their elaborate cast of supporting cells organize and coordinate their tasks. As demonstrated in the other chapters of this book, the mapping of the human mind (mostly by measuring regional changes in blood flow, initially by positron emission tomography (PET) and recently by functional magnetic resonance imaging or (fMRI)) has provided insight into the functional neuroanatomy of neuropsychiatric diseases. Amazingly, the idea that regional cerebral blood flow (rCBF) is related intimately to brain function goes back more than a century. As is often the case in science, this idea was initially the result of unexpected observations. The Italian physiologist Angelo Mosso first expressed the idea while studying pulsations of the living human brain that keep pace with the heartbeat (Mosso, 1881). These brain pulsations can be observed on the surface of the fontanelles in newborn children. Mosso believed that they reflected blood flow to the brain. He observed similar pulsations in an adult with a post-traumatic skull defect over the frontal lobes. While studying this subject, a peasant named Bertino, Mosso observed a sudden increase in the magnitude of the ‘brain’s heart-beats’ when the church bells signalled 12 o’clock, the time for a required prayer. The changes in brain pulsations occurred independently of any change in pulsations in the forearm.. (shrink)

This introduction to these and many of the other problems posed by consciousness discusses the most important work of cognitive science, neurophysiology and philosophy of the past thirty years and presents an up-to-date assessment of the issues and debates. CONTENTS: Preface and acknowledgements Introduction: problems of consciousness 1. Refection on consciousness before the mid-twentieth century 2. Functional neuroanatomy 3. Primate neuropsychology 4. Human evolution 5. Contemporary neuropsychology 6. Neuropsychology of consciousness 7. Philosophy of mind and consciousness 8. Reduction (...) and non-reduction 9. Emergence 10. Prospects for neural theories of consciousness Notes Bibliography Index. (shrink)

The controversy of neuroanatomy on the principal structure of the nervous systems, which took place at the end of the nineteenth century, is described. Two groups of scientists are identified: one that favoured the idea of a discrete cellular organization of the nervous tissue, and one that favoured a syncytial organization. These two interpretations arose from different histological techniques that produced conflicting pictures of the organization of the nervous tissue. In an experimental reexamination of the techniques used at the (...) end of the nineteenth century, the present study concerns the impact of these different histological procedures on the controversy about the principle nature of the nervous tissue. This controversy could not be resolved by neuroanatomy itself until the 1950s when electron microscopy was introduced into neurobiology. Thus, in a critical period of the conceptual development of neurosciences, neuroanatomy failed to establish a proper base for an interpretation of the functional morphology of nervous tissues. (shrink)

In arguing against the likelihood of consciousness in non-human animals, Descartes advances a slippery slope argument that if thought were attributed to any one animal, it would have to be attributed to all, which is absurd. This paper examines the foundations of Thomas Willis’ comparative neuroanatomy against the background of Descartes’ slippery slope argument against animal consciousness. Inspired by Gassendi’s ideas about the corporeal soul, Thomas Willis distinguished between neural circuitry responsible for reflex behaviour and that responsible for cognitively (...) or consciously mediated behaviour. This afforded Willis a non-arbitrary basis for distinguishing between animals with thought and consciousness and those without, a methodology which retains currency for neuroscience today. (shrink)

Our sense of smell pervasively influences our most common behaviors and daily experience, yet little is known about olfactory consciousness. Over the past decade and a half research in both the fields of Consciousness Studies and Olfaction has blossomed, however, olfactory consciousness has received little to no attention. The olfactory systems unique anatomy, functional organization, sensory processes, and perceptual experiences offers a fecund area for exploring all aspects of consciousness, as well as a external perspective for re-examining the assumptions (...) of contemporary theories of consciousness. It has even been suggested that the olfactory system may represent the minimal neuroanatomy that is required for conscious processing. Here, we seek contributions that should serve as the foundation for future research concerning consciousness using olfaction as a model. -/- Given the variegated nature of research on consciousness, we seek original papers including review articles, original research, and theoretical contributions concerning the nature of olfactory consciousness. The scope of the special edition widely incorporates olfaction as it relates to Consciousness, Awareness, Attention, Phenomenal- or Access-Consciousness, and Qualia. Research concerning olfaction and cross-modal integration as it relates to conscious experience is also welcome. -/- As the initial foray into this uncharted area of research, we welcome contributions from across all disciplines contributing to cognitive neuroscience, including neurobiology, neurology, psychology, philosophy, linguistics, and computer sciences. It is our hope that this special edition will serve as the impetus for future interdisciplinary research on olfaction and consciousness. (shrink)

As we move around in our environment, and interact with it, many of the most important problems we face involve the processing of spatial information. We have to be able to navigate by perceiving and remembering the locations and orientations of the objects around us relative to ourself; we have to sense and act upon these objects; and we need to move through space to position ourselves in favourable locations or to avoid dangerous ones. While this appears so simple that (...) we don't even think about it, the difficulty of solving these problems has been shown in the repeated failure of artificial systems to perform these kinds of tasks efficiently. In contrast, humans and other animals routinely overcome these problems every single day. This book examines some of the neural substrates and mechanisms that support these remarkable abilities. The hippocampus and the parietal cortex have been implicated in various core spatial behaviours, such as the ability to localise an object and navigate to it. Damage to these areas in humans and animals leads to impairment of these spatial functions. This collection of papers, written by internationally recognized experts in the field, reviews the evidence that each area is involved in spatial cognition, examines the mechanisms underlying the generation of spatial behaviours, and considers the relative roles of the parietal and hippocampal areas, including how each interacts with the other. The papers integrate a wide range of theoretical and experimental approaches, and touch on broader issues relating to memory and imagery. As such, this book represents the state of the art of current research into the neural basis of spatial cognition. It should be of interest to anyone - researchers or graduate students - working in the areas of cognitive neuroscience, neuroanatomy, neuropsychology, and cognition generally. (shrink)

Neural Darwinism (ND) is a large scale selectionist theory of brain development and function that has been hypothesized to relate to consciousness. According to ND, consciousness is entailed by reentrant interactions among neuronal populations in the thalamocortical system (the ‘dynamic core’). These interactions, which permit high-order discriminations among possible core states, confer selective advantages on organisms possessing them by linking current perceptual events to a past history of value-dependent learning. Here, we assess the consistency of ND with 16 widely recognized (...) properties of consciousness, both physiological (for example, consciousness is associated with widespread, relatively fast, low amplitude interactions in the thalamocortical system), and phenomenal (for example, consciousness involves the existence of a private flow of events available only to the experiencing subject). While no theory accounts fully for all of these properties at present, we find that ND and its recent extensions fare well. (shrink)

A unifying theory of general anesthetic-induced unconsciousness must explain the common mechanism through which various anesthetic agents produce unconsciousness. Functional-brain-imaging data obtained from 11 volunteers during general anesthesia showed specific suppression of regional thalamic and midbrain reticular formation activity across two different commonly used volatile agents. These findings are discussed in relation to findings from sleep neurophysiology and the implications of this work for consciousness research. It is hypothesized that the essential common neurophysiologic mechanism underlying anesthetic-induced unconsciousness is, as (...) with sleep-induced unconsciousness, a hyperpolarization block of thalamocortical neurons. A model of anesthetic-induced unconsciousness is introduced to explain how the plethora of effects anesthetics have on cellular functioning ultimately all converge on a single neuroanatomic/neurophysiologic system, thus providing for a unitary physiologic theory of narcosis related to consciousness. (shrink)

The important Hebbian architecture for language may not be the phonological networks of perisylvian cortex, but rather the semantic networks of limbic cortex. Although the high-frequency EEG findings are intriguing, the results may not yet warrant a confident theory of neural assemblies. Nonetheless, Pulvermüller succeeds in framing a comprehensive theory of language function in the literal terms of neuroanatomy and neurophysiology.

The target article is an elegant synthesis of the developmental and functional data and views on the evolutionary origin of the mammalian isocortex, integrating results from cell and molecular biology, experimental neuroanatomy, and chemoarchitectonic studies. Complementarily, we give here an account of two modes of isocortical evolution (prosomere reshuffling and invention) in terms of costs of radiation and neural tissue.

Evolutionary thinking has expanded in the last decades, spreading from its traditional stronghold - the explanation of speciation and adaptation in Biology - to new domains including the human sciences. The essays in this collection attest to the illuminating power of evolutionary thinking when applied to the understanding of the human mind. The contributors to Cognition, Evolution and Rationality use an evolutionary standpoint to approach the nature of the human mind, including both cognitive and behavioral functions. Cognitive science is by (...) its nature an interdisciplinary subject and the essays use a variety of disciplines including the Philosophy of Science, the Philosophy of Mind, Game Theory, Robotics and Computational Neuroanatomy to investigate the workings of the mind. The topics covered by the essays range from general methodological issues to long-standing philosophical problems such as how rational human beings actually are. This book will be of interest across a number of fields, including philosophy, evolutionary theory and cognitive science. (shrink)

Evolutionary thinking has expanded in the last decades, spreading from its traditional stronghold – the explanation of speciation and adaptation in biology - to new domains. Fascinating pieces of work, the essays in this collection attest to the illuminating power of evolutionary thinking when applied to the understanding of the human mind. The contributors to_ Cognition, Evolution and Rationality_ use an evolutionary standpoint to approach the nature of the human mind, including both cognitive and behavioural functions. Cognitive science is by (...) its nature an interdisciplinary subject and the essays in this collection investigate the workings of the mind through a variety of disciplines including the philosophy of science, the philosophy of mind, game theory, robotics and computational neuroanatomy. Topics covered range from general methodological issues to long-standing philosophical problems such as how rational human beings actually are. With contributions from leading experts in the areas involved, this book will be of interest across a number of fields, including philosophy, evolutionary theory and cognitive science. (shrink)

Evolutionary thinking has expanded in the last decades, spreading from its traditional stronghold – the explanation of speciation and adaptation in biology - to new domains. Fascinating pieces of work, the essays in this collection attest to the illuminating power of evolutionary thinking when applied to the understanding of the human mind. The contributors to_ Cognition, Evolution and Rationality_ use an evolutionary standpoint to approach the nature of the human mind, including both cognitive and behavioural functions. Cognitive science is by (...) its nature an interdisciplinary subject and the essays in this collection investigate the workings of the mind through a variety of disciplines including the philosophy of science, the philosophy of mind, game theory, robotics and computational neuroanatomy. Topics covered range from general methodological issues to long-standing philosophical problems such as how rational human beings actually are. With contributions from leading experts in the areas involved, this book will be of interest across a number of fields, including philosophy, evolutionary theory and cognitive science. (shrink)

The proposal that the hippocampus is important for the encoding of episodic information, but not familiarity-based recognition, is incompatible with the available data. An alternative way to think about functional specialization within the medial temporal lobe memory system is suggested, based on neuroanatomy.

It has long been suspected that attentional processes differ between olfaction and the other senses. Here, we test whether voluntary dishabituation, seen, for example, when we re-attend to the ticking of a clock, can occur in olfaction. Participants were seated in an odorized room, where at various intervals they had to evaluate what they could smell. An experimental group had one nostril open and the other closed, except during the evaluations, so that the closed side was subject to centrally driven (...) habituation, but not peripheral adaptation. A control group had both nostrils closed except during evaluations. Following exposure, the experimental group could not report the room's odor in either the centrally habituated nostril or the nostril that remained open, while the control group could. This effect could result from a number of causes, including olfaction's unique neuroanatomy, functional constraints imposed by detecting volatile chemicals, and as a consequence of limited cortical resources, with implications for the functional value of consciousness. (shrink)

: In this paper I argue that Velmens’ reflexive model of perceptual consciousness is useful for understanding the first-person perspective and sentience in animals. I then offer a defense of the proposal that ray-finned bony fish have a first-person perspective and sentience. This defense has two prongs. The first prong is presence of a substantial body of evidence that the neuroanatomy of the fish brain exhibits basic organizational principles associated with consciousness in mammals. These principles include a relationship between (...) a second-order sensory relay, the preglomerular complex, and the fish pallium which bears a resemblance to the relationship between the mammalian thalamus and the neocortex, the existence of feedback/feedforward and reentrant circuitry in the pallium, and structural and functional differences among divisions of the fish pallium. The second prong is the existence of behaviors in fish that exhibit significant flexibility in the presence of environmental change and require relational learning among stimuli distributed in space, over time, or both. I conclude that, although they are instantiated differently, a first-person perspective and sentience are present in fish. Resumo: Neste artigo, argumento que o modelo reflexivo de consciência perceptiva de Velmans é útil para se entender a perspectiva de primeira pessoa e a sentiência em animais. Em seguida, ofereço uma defesa da proposta de que os peixes ósseos com nadadeiras raiadas tenham sentiência e perspectiva de primeira pessoa. Esta defesa tem dois momentos. O primeiro ponto é a presença de um corpo substancial de evidências de que a neuroanatomia do cérebro de peixes exibe os princípios organizacionais básicos associados à consciência em mamíferos. Esses princípios incluem a interação entre um relê sensorial de segunda ordem e o pálio, os quais apresentam, respectivamente, estreita semelhança com o tálamo e o neocórtex dos mamíferos; a existência de circuitos de retroalimentação e reentrada, assim como diferenças estruturais e funcionais entre as divisões do pálio. A segunda questão é a existência de comportamentos de peixes que exibem flexibilidade significativa na presença de mudanças ambientais e requerem aprendizado relacional entre estímulos distribuídos no espaço, ao longo do tempo, ou ambos. Concluo que, embora sejam instanciados de maneira diferente dos mamíferos, uma perspectiva de primeira pessoa e sentiência estão presentes nos peixes. (shrink)

Arbib et al. describe mathematical and computational models in neuroscience as well as neuroanatomy and neurophysiology of several important brain structures. This is a useful guide to mathematical and computational modelling of the structure and function of nervous system. The book highlights the need to develop a theory of brain functioning, and it offers some useful approaches and concepts.

In general, we endorse Aggleton & Brown's thesis that the neuroanatomy of amnesia comprises two functionally distinct systems, but we are disappointed in the lack of detail regarding the critical functional contribution of the hippocampus. We also take issue with the characterization of the cortical areas surrounding the hippocampus, particularly the decreased emphasis on the cortical input to the hippocampus.

The first brief description is given of a project aimed at searching for the neural correlates of consciousness through computer simulation. The underlying model is based on the known circuitry of the mammalian nervous system, the neuronal groups of which are approximated as binary composite units. The simulated nervous system includes just two senses - hearing and touch - and it drives a set of muscles that serve vocalisation, feeding and bladder control. These functions were chosen because of their relevance (...) to the earliest stages of human life, and the simulation has been given the name CyberChild. The system's pain receptors respond to a sufficiently low milk level in the stomach, if there is simultaneously a low level of blood sugar, and also to a full bladder and an unchanged diaper. It is believed that it may be possible to infer the presence of consciousness in the simulation through observations of CyberChild's behaviour, and from the monitoring of its ability to ontogenetically acquire novel reflexes. The author has suggested that this ability is the crucial evolutionary advantage of possessing consciousness. The project is still in its very early stages, and although no suggestion of consciousness has yet emerged, there appears to be no fundamental reason why consciousness could not ultimately develop and be observed. (shrink)

Cognitive and Social Neuroscience of Aging is an introduction to how aging affects the brain, intended for audiences with some knowledge of psychology, aging, or neuroscience. The book includes figures illustrating brain regions so that extensive familiarity with neuroanatomy is not a pre-requisite. The depth of coverage also makes this book appropriate for those with considerable knowledge about aging. This book adopts an integrative perspective, including topics such as memory, cognition, cognitive training, emotion, and social processes. Topics include consideration (...) of individual differences and the impact of disorders on brain function with age. Although many declines occur with age, cognitive neuroscience research reveals plasticity and adaptation in the brain as a function of normal aging. This book is written with this perspective in mind, emphasizing the ways in which neuroscience methods have enriched and changed thinking about aging. (shrink)

Possible systemic effects of general anesthetic agents on neural information processing are discussed in the context of the thalamocortical suppression hypothesis presented by Drs. Alkire, Haier, and Fallon (this issue) in their PET study of the anesthetized state. Accounts of the neural requisites of consciousness fall into two broad categories. Neuronal-specificity theories postulate that activity in particular neural populations is sufficient for conscious awareness, while process-coherence theories postulate that particular organizations of neural activity are sufficient. Accounts of anesthetic narcosis, on (...) the other hand, explain losses of consciousness in terms of neural signal-suppressions, transmission blocks, and the disruptions of signal interpretation. While signal-suppression may account for the actions of some anesthetic agents, the existence of anesthetics, such as choralose, that cause both loss of consciousness and elevated discharge rates, is problematic for a general theory of narcosis that is based purely on signal suppression and transmission-block. However, anesthetic agents also alter relative firing rates and temporal discharge patterns that may disrupt the coherence of neural signals and the functioning of the neural networks that interpret them. It is difficult at present, solely on the basis of regional brain metabolic rates, to test process-coherence hypotheses regarding organizational requisites for conscious awareness. While these pioneering PET studies have great merit as panoramic windows of mind-brain correlates, wider ranges of theory and empirical evidence need to be brought into the formulation of truly comprehensive theories of consciousness and anesthesia. (shrink)

On the basis of knowledge prior to 1988, Ashbrook pointed out that whereas most men are primarily dependent on the left cerebral hemisphere (“dominant hemisphere”) for verbally related functions, women show a greater hemispheric balance in this respect. For men, he argues, their possession of a “speaking” and a “non‐speaking hemisphere” results in a positive‐negative, bipolar way of thinking that may be characterized as dualistic and dialectically hierarchical. In contrast, the greater balance of hemispheric function in women appears to promote (...) greater generalization and synthesis in their thinking.In this article I cite more recent neuroanatomical and brain imaging studies that provide further evidence of disparities in structure and function of the brains of men and women. As background for an attempt to explain these differences, I give a brief review of the triune evolution of the mammalian brain leading up to the human cerebrum. It is of major significance that the female has played a central role in mammalian evolution for more than 180 million years and that the evolutionary transition from reptilian therapsids to mammals is characterized by the develoment of (1) nursing conjoined with maternal care; (2) audiovocal communication or aiding mother‐offspring contact; and (3) play. In human beings, the infant‐carrying hypothesis suggests one means by which, over generations, certain parts of a woman's right hemisphere could undergo functional and eventual anatomical expansion. The mother‐infant communication of basic mammalian sounds with vowel and consonant components suggests a basis for the origination of speech.Finally, in an expansion of Ashbrook's original thesis, we arrive at the rovocative consideration that, unlike men, with their dialectical reasoning, women, with their more balanced brain, are provided with a trialectial ladder for climbing to achieve knowledge. In terms of quantum mechanics, the particle and wave would correspond to the substance and strength of the sides of the ladder, and the derived psychic information (which is neither matter nor energy) would compare to the rungs in between. (shrink)

This is a short overview of the biological functions debate in philosophy. While it was fairly comprehensive when it was written, my short book ​A Critical Overview of Biological Functions has largely supplanted it as a definitive and up-to-date overview of the debate, both because the book takes into account new developments since then, and because the length of the book allowed me to go into substantially more detail about existing views.

In the foundations of Fechner's psychophysics, the concept of “functional relation” plays a highly relevant role in three different respects: (1) in respect to the principles of measurement, (2) in respect to the mind-body problem, and (3) in respect to the concept of a law of nature. In all three cases, it is important to explain the difference between a functional dependency of a variable upon another and a causal relationship between two (or more) variables. In all three (...) respects, Ernst Mach developed Fechner's ideas further and tried to extend the lessons he had learned from using the concept of a functional relation in psychophysics to the whole of science. For all three cases, I explain why they are still relevant for psychophysics and philosophy today. (shrink)

The etiological account of teleological function is beset by several difficulties, which I propose to solve by grafting onto the etiological theory a subordinated goal-contribution clause. This approach enables us to ascribe neither too many teleofunctions nor too few; to give a unitary, one-clause analysis that works just as well for teleological functions derived from Darwinian evolution, as for those derived from human intention; and finally, to save the etiological theory from falsification, by explaining how, in spite of appearances, the (...) theory can allow for evolutionary function loss. (shrink)