Reentry (neural circuitry)

Last updated

Reentry is a neural structuring of the brain, which is characterized by the ongoing bidirectional exchange of signals along reciprocal axonal fibers linking two or more brain areas. [1] It is hypothesized to allow for widely distributed groups of neurons to achieve integrated and synchronized firing, [2] which is proposed to be a requirement for consciousness, as outlined by Gerald Edelman and Giulio Tononi in their book A Universe of Consciousness . [3]

See also

Related Research Articles

<span class="mw-page-title-main">Consciousness</span>  Awareness of internal and external existence

Consciousness, at its simplest, is awareness of internal and external existence. However, its nature has led to millennia of analyses, explanations and debate by philosophers, theologians, and all of science. Opinions differ about what exactly needs to be studied or even considered consciousness. In some explanations, it is synonymous with the mind, and at other times, an aspect of mind. In the past, it was one's "inner life", the world of introspection, of private thought, imagination and volition. Today, it often includes any kind of cognition, experience, feeling or perception. It may be awareness, awareness of awareness, or self-awareness either continuously changing or not. The disparate range of research, notions and speculations raises a curiosity about whether the right questions are being asked.

<span class="mw-page-title-main">Neural Darwinism</span> Theory in neurology

Neural Darwinism is a biological, and more specifically Darwinian and selectionist, approach to understanding global brain function, originally proposed by American biologist, researcher and Nobel-Prize recipient Gerald Maurice Edelman. Edelman's 1987 book Neural Darwinism introduced the public to the theory of neuronal group selection (TNGS) – which is the core theory underlying Edelman's explanation of global brain function.

<span class="mw-page-title-main">Synchronization</span> Coordination of events to operate a system in unison

Synchronization is the coordination of events to operate a system in unison. For example, the conductor of an orchestra keeps the orchestra synchronized or in time. Systems that operate with all parts in synchrony are said to be synchronous or in sync—and those that are not are asynchronous.

<i>Consciousness Explained</i> 1991 book by Daniel Dennett

Consciousness Explained is a 1991 book by the American philosopher Daniel Dennett, in which the author offers an account of how consciousness arises from interaction of physical and cognitive processes in the brain. Dennett describes consciousness as an account of the various calculations occurring in the brain at close to the same time. He compares consciousness to an academic paper that is being developed or edited in the hands of multiple people at one time, the "multiple drafts" theory of consciousness. In this analogy, "the paper" exists even though there is no single, unified paper. When people report on their inner experiences, Dennett considers their reports to be more like theorizing than like describing. These reports may be informative, he says, but a psychologist is not to take them at face value. Dennett describes several phenomena that show that perception is more limited and less reliable than we perceive it to be.

<span class="mw-page-title-main">Gerald Edelman</span> American biologist

Gerald Maurice Edelman was an American biologist who shared the 1972 Nobel Prize in Physiology or Medicine for work with Rodney Robert Porter on the immune system. Edelman's Nobel Prize-winning research concerned discovery of the structure of antibody molecules. In interviews, he has said that the way the components of the immune system evolve over the life of the individual is analogous to the way the components of the brain evolve in a lifetime. There is a continuity in this way between his work on the immune system, for which he won the Nobel Prize, and his later work in neuroscience and in philosophy of mind.

The consciousness and binding problem is the problem of how objects, background and abstract or emotional features are combined into a single experience.

The electromagnetic theories of consciousness propose that consciousness can be understood as an electromagnetic phenomenon.

<span class="mw-page-title-main">Christof Koch</span> American neurophysiologist

Christof Koch is a German-American neurophysiologist and computational neuroscientist best known for his work on the neural basis of consciousness. He is the president and chief scientist of the Allen Institute for Brain Science in Seattle. From 1986 until 2013, he was a professor at the California Institute of Technology.

A Universe of Consciousness: How Matter Becomes Imagination is the title of a 2000 book by biologists Gerald Maurice Edelman and Giulio Tononi; published in UK as Consciousness: How Matter Becomes Imagination. This book, written with Giulio Tononi, is the culmination of a series of works by Gerald Edelman on the workings of the brain which include Neural Darwinism and Bright Air, Brilliant Fire.

A gamma wave or gamma rhythm is a pattern of neural oscillation in humans with a frequency between 25 and 140 Hz, the 40 Hz point being of particular interest. Gamma rhythms are correlated with large scale brain network activity and cognitive phenomena such as working memory, attention, and perceptual grouping, and can be increased in amplitude via meditation or neurostimulation. Altered gamma activity has been observed in many mood and cognitive disorders such as Alzheimer's disease, epilepsy, and schizophrenia. Elevated gamma activity has also been observed in moments preceding death.

In the field of computational neuroscience, the theory of metastability refers to the human brain's ability to integrate several functional parts and to produce neural oscillations in a cooperative and coordinated manner, providing the basis for conscious activity.

<span class="mw-page-title-main">Neural oscillation</span> Brainwaves, repetitive patterns of neural activity in the central nervous system

Neural oscillations, or brainwaves, are rhythmic or repetitive patterns of neural activity in the central nervous system. Neural tissue can generate oscillatory activity in many ways, driven either by mechanisms within individual neurons or by interactions between neurons. In individual neurons, oscillations can appear either as oscillations in membrane potential or as rhythmic patterns of action potentials, which then produce oscillatory activation of post-synaptic neurons. At the level of neural ensembles, synchronized activity of large numbers of neurons can give rise to macroscopic oscillations, which can be observed in an electroencephalogram. Oscillatory activity in groups of neurons generally arises from feedback connections between the neurons that result in the synchronization of their firing patterns. The interaction between neurons can give rise to oscillations at a different frequency than the firing frequency of individual neurons. A well-known example of macroscopic neural oscillations is alpha activity.

<span class="mw-page-title-main">Animal consciousness</span> Quality or state of self-awareness within an animal

Animal consciousness, or animal awareness, is the quality or state of self-awareness within an animal, or of being aware of an external object or something within itself. In humans, consciousness has been defined as: sentience, awareness, subjectivity, qualia, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind. Despite the difficulty in definition, many philosophers believe there is a broadly shared underlying intuition about what consciousness is.

<span class="mw-page-title-main">Giulio Tononi</span> Neuroscientist, psychiatrist, and professor

Giulio Tononi is a neuroscientist and psychiatrist who holds the David P. White Chair in Sleep Medicine, as well as a Distinguished Chair in Consciousness Science, at the University of Wisconsin. He is best known for his Integrated Information Theory (IIT), a mathematical theory of consciousness, which he has proposed since 2004.

Primary consciousness is a term the American biologist Gerald Edelman coined to describe the ability, found in humans and some animals, to integrate observed events with memory to create an awareness of the present and immediate past of the world around them. This form of consciousness is also sometimes called "sensory consciousness". Put another way, primary consciousness is the presence of various subjective sensory contents of consciousness such as sensations, perceptions, and mental images. For example, primary consciousness includes a person's experience of the blueness of the ocean, a bird's song, and the feeling of pain. Thus, primary consciousness refers to being mentally aware of things in the world in the present without any sense of past and future; it is composed of mental images bound to a time around the measurable present.

<span class="mw-page-title-main">Integrated information theory</span> Theory within consciousness research (proposed 2004)

Integrated information theory (IIT) proposes a mathematical model for the consciousness of a system. It comprises a framework ultimately intended to explain why some physical systems are conscious, and to be capable of providing a concrete inference about whether any physical system is conscious, to what degree, and what particular experience it is having; why they feel the particular way they do in particular states, and what it would take for other physical systems to be conscious.

Secondary consciousness is an individual's accessibility to their history and plans. The ability allows its possessors to go beyond the limits of the remembered present of primary consciousness. Primary consciousness can be defined as simple awareness that includes perception and emotion. As such, it is ascribed to most animals. By contrast, secondary consciousness depends on and includes such features as self-reflective awareness, abstract thinking, volition and metacognition. The term was coined by Gerald Edelman.

The Dehaene–Changeux model (DCM), also known as the global neuronal workspace or the global cognitive workspace model is a part of Bernard Baars's "global workspace model" for consciousness.

Andreas Karl Engel is a German neuroscientist. He is the director of the Department of Neurophysiology and Pathophysiology at the University Medical Center Hamburg-Eppendorf (UKE).

The term posterior cortical hot zone was coined by Christof Koch and colleagues to describe the part of the neocortex closely associated with the minimal neural substrate essential for conscious perception. The posterior cortical hot zone includes sensory cortical areas in the parietal, temporal, and occipital lobes. It is the “sensory” cortex, much as the frontal cortex is the “action” cortex.

References

  1. Edelman, Gerald M.; Gally, Joseph A. (2013). "Reentry: a key mechanism for integration of brain function". Frontiers in Integrative Neuroscience. 7 (63): 63. doi: 10.3389/fnint.2013.00063 . PMC   3753453 . PMID   23986665.
  2. Seth, A. K.; McKinstry, J. L.; Edelman, G. M.; Krichmar, J. L. (2004). "Visual binding through reentrant connectivity and dynamic synchronization in a brain-based device". Cerebral Cortex. 14 (11): 1185–99. doi: 10.1093/cercor/bhh079 . PMID   15142952.
  3. G. Edelman; G Tononi (2000). A Universe of Consciousness. Basic Books. ISBN   978-0-465-01377-7..