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Cited by 99Philosophy and Theoretical ScienceNeural dynamics and brain functionVisual perception and processing mechanisms

The functional neuroanatomy of awareness: with a focus on the role of various anatomical systems in the control of intermodal attention

Smythies, John·1997·Consciousness and Cognition
DOI 10.1006/ccog.1997.0315
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Abstract

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 of intramodal attention is controlled by the reticular nucleus of the thalamus. He also proposed different mechanisms for attention and intention ("will"). The current review presents a new hypothesis, based on elements from these hypotheses, including intermodal attention 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 (small local "flashlights" rather than one major "searchlight"). But this is constrained by the functional anatomy of the circuits concerned and waking "awareness" is modulated by the many "nonspecific" systems (cholinergic from the basal forebrain, noradrenergic from the locus coeruleus, dopaminergic from the substantia nigra and ventral tegmentum, and serotoninergic from the raphe). 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.

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  • The thalamus is a relay center in subserving sensory and motor mechanisms, awareness, attention, memory, and language.

    “The thalamus is a relay center in subserving both sensory and motor mechanisms, and awareness (Smythies, 1997), attention (Büchel et al., 1998) and other neurocognitive processes such as memory and language (Engelborghs et al., 1998, Johnson and Ojemann, 2000).”

    From The impact of atypical sensory processing on social impairments in autism spectrum disorder (2018) · cites this paper as Smythies, 1997

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Authors
Smythies, J.
Affiliations
University of California San Diego (US)
Corresponding author
Smythies, John
Venue
Consciousness and Cognition
Publisher
Elsevier BV
Published
1997-12
Volume
6
Issue
4
Pages
455-481
ISSN
1053-8100 (ISSN-L)
DOI
10.1006/ccog.1997.0315
OpenAlex
W2048823696
Cited by
99
References
156
Citations by year
2026: 1 · 2024: 1 · 2023: 1 · 2022: 1 · 2021: 2 · 2020: 4 · 2019: 1 · 2018: 3 · 2017: 4 · 2016: 2 · 2015: 1 · 2014: 3 · 2013: 8 · 2012: 8
FWCI
5.72
Type
journal article
Language
en
Open access
closed
Licence
www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations
  • Consciousness and Cognition (publishedVersion)
  • PubMed (publishedVersion)
Funders
Francis Crick Institute
Topics
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Philosophy and Theoretical Science
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Neural dynamics and brain function
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Visual perception and processing mechanisms
Keywords
neural basis of consciousness, awareness, cross-modal attention, reticular nucleus, intralaminar nuclei, cholinergic system, locus coeruleus, raphe nuclei, substantia nigra, ventral tegmental area, insula cortex, extended amygdala, attentional shift, intention, loss of consciousness, nucleus basalis of Meynert, olfaction, pain
MeSH terms
Attention, Awareness, Brain, Cholinergic Fibers, Humans, Pain, Smell, Thalamus

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