Bilateral damage to the basal ganglia causes auto-activation deficit, a neuropsychological syndrome characterized by striking apathy, with a loss of self-driven behaviour that is partially reversible with external stimulation. Some patients with auto-activation deficit also experience a mental emptiness, which is defined as an absence of any self-reported thoughts. We asked whether this deficit...
Hallucinations of musical notation may occur in a variety of conditions, including Charles Bonnet syndrome, Parkinson's disease, fever, intoxications, hypnagogic and hypnopompic states. Eight cases are described here, and their possible cerebral mechanisms discussed.
Large-scale brain networks are integral to the coordination of human behaviour, and their anatomy provides insights into the clinical presentation and progression of neurodegenerative illnesses such as Alzheimer's disease, which targets the default mode network, and behavioural variant frontotemporal dementia, which targets a more anterior salience network. Although the default mode network is...
Recent research in cognitive neuroscience using virtual reality, robotic technology and brain imaging has linked self-consciousness to the processing and integration of multisensory bodily signals. This work on bodily self-consciousness has implicated the temporo-parietal, premotor and extrastriate cortex and partly originated in work on neurological patients with different disorders of bodily...
A compelling single case report of visual awareness (visual qualia) without primary visual cortex would be sufficient to refute the hypothesis that the primary visual cortex and the back-projections to it are necessary for conscious visual experience. In a previous study, we emphasized the presence of crude visual awareness in Patient G.Y., with a lesion of the primary visual cortex, who is...
Rapid eye movements and complex visual dreams are salient features of human rapid eye movement sleep. However, it remains to be elucidated whether the eyes scan dream images, despite studies that have retrospectively compared the direction of rapid eye movements to the dream recall recorded after having awakened the sleeper. We used the model of rapid eye movement sleep behaviour disorder (when...
Animal data indicate that the recreational drug ecstasy (3,4-methylenedioxymethamphetamine) can damage brain serotonin neurons. However, human neuroimaging measurements of serotonin transporter binding, a serotonin neuron marker, remain contradictory, especially regarding brain areas affected; and the possibility that structural brain differences might account for serotonin transporter binding...
This article explores the notion that Freudian constructs may have neurobiological substrates. Specifically, we propose that Freud's descriptions of the primary and secondary processes are consistent with self-organized activity in hierarchical cortical systems and that his descriptions of the ego are consistent with the functions of the default-mode and its reciprocal exchanges with...
What is it like to be conscious? Whereas nobody knows, by definition, what is it like to be unconscious, everybody knows what is it like to be conscious. Those of our mental states that are conscious have a distinctive phenomenal character, which we can experience and report. For example, there is something about seeing things that has its own distinctive character, which differs from hearing...
BrainAugust 2009Marie Arthuis, Luc Valton, Jean Régis et al.
Loss of consciousness (LOC) is a dramatic clinical manifestation of temporal lobe seizures. Its underlying mechanism could involve altered coordinated neuronal activity between the brain regions that support conscious information processing. The consciousness access hypothesis assumes the existence of a global workspace in which information becomes available via synchronized activity within...
Attention and memory deficits have been reported in heavy marijuana users, but these effects may be reversible after prolonged abstinence. It remains unclear whether the reversibility of these cognitive deficits indicates that chronic marijuana use does not alter cortical networks, or that such changes occur but the brain adapts to the drug-induced changes. Blood oxygenation-level dependent...
BrainJanuary 2006Juergen Fell, Guillén Fernández, Martin T Lutz et al.
Compared with waking state attention, volition and semantic processing play a minor role during sleep. Thus, investigating declarative memory formation during sleep may allow us to isolate mnemonic core processes. The most feasible approach to memory formation during sleep is the analysis of dream memories. Lesion and imaging studies have demonstrated that encoding of declarative memories, i.e....
During an out-of-body experience (OBE), the experient seems to be awake and to see his body and the world from a location outside the physical body. A closely related experience is autoscopy (AS), which is characterized by the experience of seeing one's body in extrapersonal space. Yet, despite great public interest and many case studies, systematic neurological studies of OBE and AS are...
NEUROCHEMISTRY OF CONSCIOUSNESS: NEUROTRANSMITTERS IN MIND Edited by E. Perry, H. Ashton and A. Young 2002. Amsterdam: John Benjamins Publishing Company Price €65. ISBN 1588111245 Of what relevance is the study of the neural correlates of consciousness to the practice of clinical neurology? Until recently, one answer to this question might reasonably have been ‘not much’, consciousness being...
Consciousness is topical, for reasons including its renewed respectability among psychologists, rapid progress in the neuroscience of perception, memory and action, advances in artificial intelligence and dissatisfaction with the dualistic separation of mind and body. Consciousness is an ambiguous term. It can refer to (i) the waking state; (ii) experience; and (iii) the possession of any...
Six subjects with musical hallucinations following acquired deafness are described. The subjects all experienced the condition in the absence of any other features to suggest epilepsy or psychosis. I propose a neuropsychological model for the condition consistent with detailed observation of the subjects' phenomenology. The model is based on spontaneous activity within a cognitive module for...
BrainMarch 1979B Libet, E W Wright, B Feinstein et al.
Subjective experience of a peripherally-induced sensation is found to appear without the substantial delay found for the experience of a cortically-induced sensation. To explain this finding, in relation to the putative delay of up to about 500 ms for achieving the "neuronal adequacy" required to elicit the peripherally-induced experience, a modified hypothesis is proposed: for a peripheral...