6/24/2007

The Feeling of What Happens:  Body and Emotion in the Making of Consciousness

Harcourt Brace & Company

1999

Antonio R. Damasio

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Chapter eight The Neurology of Consciousness

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“…mechanisms for core consciousness and extended consciousness, and…which anatomical structures were necessary to support the proto-self and the second-order map required by those mechanisms.  (Damasio/FWH/234)”

“…maps of somatosensory information, which form the neural basis for the proto-self….(Damasio/FWH/234)”

“…level of the upper brain stem and hypothalamus, where proto-self structures are tightly packed together….at higher levels (the cortices of insula, S2, S1; related parietal association cortices), where processing chains are spatially more separated.  (Damasio/FWH/235)”

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“Bilateral damage to structures presumed to participate in constructing the second-order imaged account of the organism-object relationship should disrupt core consciousness partially or completely.  Examples of such structures are certain nuclei of the thalamus and the cingulate cortices.  (Damasio/FWH/235)”

Is this sort of an object-relations thing?  And as it forms in early attachments?

“…Damage to the temporal cortices will impair the activation of autobiographical memory records and thus reduce the scope of extended consciousness.  The same applies to bilateral damage in some higher-order cortices within the vast prefrontal regions, which also support the records from which the autobiographical self can be activated.  (Damasio/FWH/235)”

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“Bilateral damage to the hippocampus will not impair core consciousness.  However, because new learning of facts will be precluded, it will halt the growth of autobiographical memory, affect its maintenance, and, consequently, alter the quality of extended consciousness in the future.  (Damasio/FWH/235)”

Stress during childhood fried cells in my hippocampus, thus the quality of extended consciousness in my future was altered?

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“…somatosensory cortices…provide part of (Damasio/FWH/235)the basis for the proto-self.  (Damasio/FWH/236)”

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“Bilateral damage to prefrontal cortices, even if extensive, should not alter core consciousness.  (Damasio/FWH/236)”

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“The brain stem connects the spinal cord to the large expanses of the cerebral hemispheres.  …see brain part file on brain stem

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“The cingulate might actually make the critical contribution to the “feeling of knowing,” the special high-order feeling that defines core consciousness.  (Damasio/FWH/264)”

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“Sense of self and knowing still operate efficiently regarding any object that can be (Damasio/FWH/266) properly mapped.  This fact underscores the following situation:  proto-self and second-order maps depend largely on one set of paramidline structures – the brain stem, hypothalamic, basal forebrain, and the thalamic nuclei, as well as the centrally located cingulate cortices; while mapping of objects depends largely on less centrally located sensory cortices distributed over the cortical mantle.  The left and right halves of “self and knowing” structures sit centrally, just across from each other, and are often damaged together by the same pathological cause, the left and right halves of the structures on which object mapping depends sit farther apart and are often damaged independently.  (Damasio/FWH/267)”

“We can say with confidence that bilateral damage to the hippocampus, or to the entire anterior temporal lobe or to the entire lateral temporal lobe or to most of the medial and inferior temporal lobe does not cause impairments of core consciousness…Bilateral damage to the amygdalae also leaves core consciousness intact.  (Damasio/FWH/267)”

“Profound alterations of learning, memory, and language are the well-known results of such legions…They are the very conscious owners of disrupted memories and broken language.  (Damasio/FWH/267)”

“Likewise, bilateral or unilateral damage to auditory cortices, visual cortices, and prefrontal cortices does not impair core consciousness at all.  (Damasio/FWH/267)”

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I move a bunch into emotion and feeling chapter of Damasio/FWH

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“…although even the simplest core consciousness requires ensemble activity that involves regions of every tier and quarter of the brain, consciousness does depend most critically on regions that are evolutionarily older, rather than more recent, and are located in the depth of the brain, rather than on its surface.  In a curious way, the “second-order” processes I propose here are anchored on ancient neural structures, intimately associated with the regulation of life, rather than on the modern neural achievements of the neocortex, those which permit fine perception, language, and high reason.  The apparent “more” of consciousness depends on “less,” and the second-order is, in the end, a deep and low order.  The light of consciousness is carefully hidden and venerably ancient.  (Damasio/FWH/275)”

“Let me note that this is a fact, not a hypothesis – whether my hypotheses turn out to be correct or not, the fact remains that damage to these sites impairs consciousness, while damage elsewhere does not.  The least that can be said about this fact is that it seems counterintuitive.  We rightly think of consciousness as a significant biological advancement, even when we grant consciousness to nonhuman creatures.  Well, the advancement is certainly significant, but it may be (Damasio/FWH/275) older than usually thought.  What is not so old, evolutionarily speaking, is the extension of consciousness that has been allowed by memory, first, by permitting us to establish an autobiographical record; second, by giving us a broad record of other facts; and third, by endowing us with the holding power of working memory.  Surely enough, these extensions of consciousness, which have blossomed so powerfully in humans, are based on the evolutionarily modern aspects of the brain, namely those of the neocortex.  In the end, however, none of those astounding new features of consciousness occur independently of the modest feats of core consciousness.  (Damasio/FWH/276)”

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The Feeling of What Happens:  Body and Emotion in the Making of Consciousness

Harcourt Brace & Company

1999

Antonio Damasio

Appendix

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“There are billions of neurons in the human brain, organized in local circuits.  Those circuits constitute cortical regions, if they are arranged in parallel layers, like a cake, or nuclei, if they are grouped in nonlayered collections, like berries in a bowl.  Both the cortical regions and the nuclei are interconnected by axon “projections” to form systems, and, at gradually higher levels of complexity, systems of systems.  When the axon projections are large enough to be individualized to the naked eye they form “pathways.”  In terms of scale, all neurons and local circuits are microscopic, while cortical regions, most nuclei, and systems are macroscopic.  (Damasio/FWH/325)”

“The actions of neurons depends on the nearby assembly of neurons they belong to; whatever systems do depends on how assemblies influence other assemblies in an architecture of interconnected assemblies; and finally, whatever each assembly contributes to the function of the system to which it belongs, depends on its place in that system.  The varied functions of different brain areas are a consequence of the place assumed by assemblies of sparsely connected neurons within large-scale systems.  In short, the brain is a system of systems.  Each system is composed of an elaborate interconnection of small but macroscopic cortical regions and subcortical nuclei, which are made of microscopic local circuits, which are made of neurons, all of which are connected by synapses.  (Damasio/FWH/331)”

“For the purposes of anatomical description, the nervous system is usually divided into central and peripheral divisions.  The main component of the central nervous system is the cerebrum, which is made up of the left and right cerebral hemispheres joined by the corpus callosum (a thick collection of nerve fibers connecting left and right hemispheres bidirectionally).  The central nervous system also encompasses deep nuclei such as:  (a) the basal ganglia; (b) the basal forebrain; and (c) the diencephalon (a combination of the thalamus and the hypothalamus).  The cerebrum is joined to the spinal cord by the brain stem, behind which you can find the cerebellum….  (Damasio/FWH/325)”

“The central nervous system is connected to every point of the body by nerves, which are bundles of axons originating in the cell body of neurons.  The collection of all nerves connecting the central nervous system (brain, for short) with the periphery and vice versa constitutes the peripheral nervous system.  Nerves transmit impulses from brain to body and from body to brain.  The brain and the body are also interconnected chemically, by substances such as hormones which course in the bloodstream. (Damasio/FWH/325)”

“A section of the central nervous system, in any direction you may wish to slice it, easily reveals a difference between dark and pale sections.  The dark sectors are known as the gray matter (although their real color is more brown than gray), and the pale sectors are known as the white matter (which is not that white, either).  The gray matter gets its (Damasio/FWH/325) darker hue from the tight packing of massive numbers of neuron cell bodies.  The nerve fibers, which emanate from the cell bodies located in the gray matter, constitute the white matter.  The myelin sheath, which insulates the nerve fibers, gives the white matter its characteristic lighter appearance.  (Damasio/FWH/327)”

“The gray matter comes in two varieties.  Examples of the layered variety are the cerebral cortex which envelops the cerebral hemispheres, and the cerebellar cortex which envelops the cerebellum.  Examples of the nonlayered variety, the nuclei, include:  the basal ganglia (located in the depth of each cerebral hemisphere and made up of three large nuclei, the caudate, putamen, and pallidum); the amygdala, a single and sizable lump of nuclei located in the depth of each temporal lobe; and several aggregations of smaller nuclei which form the thalamus, the hypothalamus, and the gray sectors of the brain stem.  (Damasio/FWH/327)”

“The cerebral cortex can be envisioned as a comprehensive mantle for the cerebrum, covering the surfaces of the cerebral hemisphere, including those that are located in the depths of fissures and sulci, the crevices which give the brain its characteristic folded appearance.  The thickness of this multilayer mantle is about three millimeters, and the layers are parallel to each other and to the brain’s surface.  The evolutionarily modern part of the cerebral cortex is known as the neocortex.  The cerebral cortex is an overwhelming presence, and all other gray structures, the various nuclei mentioned above, and the cerebellar cortex are known as subcortical.  The main divisions of the cerebral cortex are designated as lobes:  frontal, temporal, parietal, and occipital.  (Damasio/FWH/327)”

“The various regions of the cortical lobes are traditionally identified by numbers corresponding to the distinctive architecture of its cellular arrangements (which is known as cytoarchtectonics).  The numbering of the regions originated with the work of Korbinian Brodmann, and remains a valid tool after nearly a century.  The numbers need to be learned, or checked in a map, and have nothing to do with the area’s size or importance.  (Damasio/FWH/327)”

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BRAIN SYSTEMS BEHIND THE MIND

“For THE purpose of investigating the relation between mental images and the brain, I have long used a framework….[which] posits an image space and a dispositional space.  The image space is that in which images of all sensory types occur explicitly.  Some of those images constitute the manifest mental contents that consciousness lets us experience whereas some images remain nonconscious.  The dispositional space is that in which dispositions contain the knowledge base and the mechanisms with which images can be constructed from recall, with which movements can be generated, and with which the processing of images can be facilitated.  Unlike the (Damasio/FWH/331) contents of the image space, which are explicit, the contents of the dispositional space are implicit.  We can know the contents of images (once core consciousness is activated), but we never know the contents of dispositions directly.  The contents of dispositions are always nonconscious and exist in dormant form.  Yet dispositions can produce a large variety of actions – the release of a hormone into the bloodstream; the contraction of muscles in viscera or of muscles in a limb or in the vocal apparatus.  Dispositions hold some records for an image that was actually perceived on some previous occasion and participate in the attempt to reconstruct a similar image from memory.  Dispositions also assist with the processing of a currently perceived image, for instance, by influencing the degree of attention accorded to the current image.  We are never aware of the knowledge necessary to perform any of these tasks, nor are we ever aware of the intermediate steps that are taken.  We are only aware of results, for example, a state of well-being; the racing of the heart; the movement of a hand; the fragment of a recalled sound; the edited version of the ongoing perception of a landscape.  (Damasio/FWH/332)”

“All of our memory, inherited from evolution and available at birth, or acquired through learning thereafter, in short, all of our memory of things, of properties of things, of persons and places, of events and relationships, of skills, of biological regulations, you name it, exists in dispositional form (a synonym for implicit, covert, nonconscious), waiting to become an explicit image or action.  Note that dispositions are not words.  They are abstract records of potentialities.  Words or signs, which can signify any entity or event or relationship, along with the rules with which we put words and signs together also exist as dispositions and come to life as images and action, as in speech or signing.  When I think of dispositions I always think of the town of Brigadoon waiting to come alive for a brief period.  (Damasio/FWH/332)”

“We are beginning to discern which parts of the central nervous system support the image space and which parts support the dispositional space.  The areas of cerebral cortex located in and around the arrival point of visual, auditory, and other sensory signals – the so- (Damasio/FWH/332) called early sensory cortices of the varied sensory modalities – support explicit neural patterns, and so do parts of limbic areas, such as the cingulate, and noncortical structures, such as the tectum.  These neural patterns of maps continuously change under the influence of internal and external inputs and are likely to be the basis for images, whose mercurial dynamics parallel the neural pattern changes over time.   (Damasio/FWH/333)”

“On the other hand, higher-order cortices – which make up the ocean of cerebral cortex around the islands of early sensory cortices and motor cortices – parts of limbic cortices, and numerous subcortical nuclei, for the amygdala to the brain stem, hold dispositions, that is, implicit records of knowledge….When disposition circuits are activated they signal to other circuits and cause images or actions to be generated from elsewhere in the brain.  (Damasio/FWH/333)”

“This bare sketch also requires the mention of other brain regions whose ostensible role is the interrelation of signals across brain areas, along with the control of their occurrence in certain brain areas.  Those regions include the thalamus, the basal ganglia, the hippocampus, and the cerebellum.  (Damasio/FWH/333)”

“I have proposed that dispositions are held in neuron ensembles called convergence zones.  To the partition between an image space and a dispositional space, then, corresponds a partition in (1) explicit neural pattern maps – activated in early sensory cortices, in so-called limbic cortices, and in some subcortical nuclei; and in (2) convergence zones, located in higher-order cortices and in some subcortical nuclei.  (Damasio/FWH/333)”

“The question is generally known as the “binding” problem.  In terms of an overall mental picture it is likely that binding requires some form of time-locking of neural activities that occur in separate but interconnected brain regions.  There is little doubt that the integrated and unified scene that characterizes the conscious mind will require massive local and global signaling of populations of neurons across multiple brain regions…..attempts to capture a mechanism capable of making the necessarily fragmented activity of our brain cohere in time and space….(Damasio/FWH/335)”  [he is listing many others’ work here as potential directions for solving this problem]