Changeux; Neuronal Man
Book Page   Topic    
Changeux; Neuronal Man 20 Brodmann Areas defined in 1909 on the basis of differences in thin cortical sections.
Changeux; Neuronal Man 24 1950, electron microscope 4
Changeux; Neuronal Man 28 Electron microscope magnification 1000x greater than light microscope. 10-9 meters, nanometer. 4
Changeux; Neuronal Man 28 Synapse, Charles Sherrington, 1897; 20 nm wide gap 0
Changeux; Neuronal Man 34 Acetylcholine and adrenaline, neurotransmitters 6
Changeux; Neuronal Man 39 Human brain average 1330 gm, wide variation, 1000-2000 gm. 5
Changeux; Neuronal Man 40 Absolute weight of brain is of no significance. 1
Changeux; Neuronal Man 41 Variation in brain weight with body weight - (graph) 1
Changeux; Neuronal Man 43 Brain of fish, basal ganglia (control of movement), thalamus (relay in pathways going to hemispheres), hypothalamus (controlling basic behavior, regulating secretion of hormones), cerebellum (organ of balance) dorsal wall of posterior ventricle. 2
Changeux; Neuronal Man 44 Fish, highly developed sense of smell, search for food. Cerebral hemispheres very thin, specialized for olfaction. 1
Changeux; Neuronal Man 44 Amphibians and reptiles, similar olfactory center, ventral half of each hemisphere. 0
Changeux; Neuronal Man 44 Mammals and humans, olfactory center a pear-shaped lobe on lower surface of brain. 0
Changeux; Neuronal Man 44 In partially terrestrial amphibians and the reptiles, the senses, particularly vision, associate sensing and motion functions in the dorsal parts of the hemispheres. In humans, it becomes the hippocampus. 0
Changeux; Neuronal Man 44 Neocortex, projection functions of the sense organs, association functions. 0
Changeux; Neuronal Man 44 Schematic diagram showing the brain common to all vertebrates including humans. (diagram) 0
Changeux; Neuronal Man 45 Diagram showing the expansion of the neocortex from reptiles through a primitive marsupial to man. The most primitive part of the cortex is specialized for olfaction. One primitive area goes 'inside' to form the hippocampus in mammals. Neocortex is small or absent in reptiles. Basal ganglia, ventricles. 1
Changeux; Neuronal Man 45 Fully mature cerebral cortex, mean surface area, 2200 cm2 0
Changeux; Neuronal Man 45 Two-thirds of the cortex is hidden in sulci, or fissures. 0
Changeux; Neuronal Man 45 Number of convolutions, or gyri, increases from almost none in primitive animals through the primates to reach a maximum in humans. 0
Changeux; Neuronal Man 46 Mammalian neocortex is made up of gray and white matter. 1
Changeux; Neuronal Man 46 Neocortex    presents a stratified structure    with six parallel layers. 0
Changeux; Neuronal Man 46 Pyramidal cells,    predominant type,    outnumber all others. 0
Changeux; Neuronal Man 47 The main cell categories    in the cerebral cortex -    pyramidal cells,    stellate cells,    etc. - (illustration) 1
Changeux; Neuronal Man 48 Pyramidal cells,    apical dendrite,    basal dendrite;    spines ~20k per pyramidal cell    cover the dendrites.    Axon of pyramidal cell    runs downward    with collateral branches. 1
Changeux; Neuronal Man 48 Pyramidal cell axons,    major output, or efferent, pathway    from the cerebral cortex. 0
Changeux; Neuronal Man 48 Stellate cells,    interneurons,    communication between pyramidal cells. 0
Changeux; Neuronal Man 48 Pyramidal and stellate cells    are not distributed uniformly    throughout the cortical thickness. 0
Changeux; Neuronal Man 48 Layer I, no pyramidal neurons. 0
Changeux; Neuronal Man 48 Layers II, III,     V, VI, lots of pyramidal cells. 0
Changeux; Neuronal Man 48 Layer IV, stellate cells sandwiched in. 0
Changeux; Neuronal Man 49 Cellular architecture of the cortex    varies from one area to another -    sensory cortex;    motor cortex. - (illustration) 1
Changeux; Neuronal Man 50 Cerebral cortex -- made up of a small number of cellular elements    repeated many times. 1
Changeux; Neuronal Man 50 Same categories of cell    are found at all stages of evolution    from primitive mammals to humans. 0
Changeux; Neuronal Man 50 No cell categories    are specific to the human cortex. 0
Changeux; Neuronal Man 50 In spite of the relative uniformity    in the organization of the cerebral cortex,    there are some differences    between areas. 0
Changeux; Neuronal Man 50 Cortex is not equally thick everywhere,    and the density of cells    and the distribution of different neuron categories through the six layers    vary from one area to another. 0
Changeux; Neuronal Man 50 The thin primary visual projection area    (Brodmann's area 17)    contains abundant stellate cells. 0
Changeux; Neuronal Man 50 The remarkably thick motor cortex    (Brodmann's area 4)    has many large pyramidal cells. 0
Changeux; Neuronal Man 51 Categories of pyramidal and stellate cells    are the same    from mouse to humans. 1
Changeux; Neuronal Man 51 Total number of cells under a given surface area    does not vary    in the course of mammalian evolution. 0
Changeux; Neuronal Man 51 146,000 neurons per square millimeter    of cortical surface    in all mammalian species. 0
Changeux; Neuronal Man 52 There must be about 1014 to 1015 synapses in the human cortex. 1
Changeux; Neuronal Man 54 Distribution of cell types    varies    from one cortical layer to another. 2
Changeux; Neuronal Man 54 Whatever the sensory modality,    axons stop on their way    principally in the thalamus.    Thalamic neurons then continue to the cortex. 0
Changeux; Neuronal Man 55 Axons from the thalamus    are not the only incoming, or afferents,    to the cortex.   Fibers coming from the cortex itself constitute another important input. 1
Changeux; Neuronal Man 55 Each cortical area receives a considerable number of axons coming from other areas of the same or opposite hemisphere.    Association fibers, associate several areas. 0
Changeux; Neuronal Man 55 Input and output pathways    of the cerebral cortex. - (illustration) 0
Changeux; Neuronal Man 56 Thalamic fibers stop in well-defined layers,    particularly layer IV and part of layer III.    Layer IV can be considered the main gateway to the cortex. 1
Changeux; Neuronal Man 56 Pyramidal cell axons form the main output of the cortex. 0
Changeux; Neuronal Man 56 First output of the cortex is back to the cortex itself,    either on the same side or opposite side;    association connections;    other outgoing (efferent axons) end outside the cortex    to subcortical levels. 0
Changeux; Neuronal Man 56 It seems the function of many cortical signals is to feed back information to the cortex itself. 0
Changeux; Neuronal Man 56 Three major outputs from the cortex: (1) cortex itself, (2) thalamus, (3) outputs of motor commands, which are expressed as behavior. 0
Changeux; Neuronal Man 57 Main entries to the cortex    are the axons coming from the neurons of the thalamus.    Some fibers leave the cortex and return to the thalamus.    Feedback circuits. 1
Changeux; Neuronal Man 57 Pyramidal cells that send axons to the thalamus    are located in the deepest layer of the cortex (layer VI)    or in the lower part of Layer V. 0
Changeux; Neuronal Man 57 Pyramidal cells sending axons to nonthalamic subcortical centers    are situated in layer V. 0
Changeux; Neuronal Man 57 Axons that project back to the cortex    come from layers II and III. 0
Changeux; Neuronal Man 57 Cortical connections conform to a number of organizational guidelines    common to the entire cortex. 0
Changeux; Neuronal Man 57 General principles of wiring are the same throughout the cortex, regardless of the functional specialization. The network consists of the same cell categories and of similar numbers of cells in each category. 0
Changeux; Neuronal Man 62 Cerebellar cortex in higher vertebrates, including humans,    contains five types of cells    repeated many times. 5
Changeux; Neuronal Man 62 Only the Purkinje cells send their axons out of the cortex. 0
Changeux; Neuronal Man 62 Purkinje cells form only one layer. 0
Changeux; Neuronal Man 64 Pyramidal cells of layer V of the motor cortex;    axons go as far as the spinal cord;    giant cell bodies. 2
Changeux; Neuronal Man 65 Major event in the evolution of the mammalian brain, expansion of the neocortex. 1
Changeux; Neuronal Man 65 Mouse to human,    Expansion of the neocortex;    increase in the total number of neurons;    number of cellular elements per unit of surface area    has not changed. 0
Changeux; Neuronal Man 66 Cortex of human    3x thicker than mouse,    not uniform in all layers;    particularly affects layers III and V,    the main source of cortical-to-cortical connections. 1
Changeux; Neuronal Man 66 Mouse to human,    surface area of cortex expands,    area of association cortex becomes relatively greater    than that of the primary sensory and motor areas. 0
Changeux; Neuronal Man 66 Mouse to human,    increase in the mean number of connections per neuron,    burgeoning of the dendritic and axonal trees. 0
Changeux; Neuronal Man 66 Density of synapses per cubic millimeter of cortex    is the same order    in rat as in man. 0
Changeux; Neuronal Man 66 No sudden qualitative reorganization    marks the passage from "animal" brain to human,    continuous quantitative evolution. 0
Changeux; Neuronal Man 68 Electric eel discharge, 300v, 0.5 amp 2
Changeux; Neuronal Man 68 EEG 1929, a few tens of microvolts,    oscillate at low frequency. 0
Changeux; Neuronal Man 68 Alpha waves, person resting, eyes closed, ~10 Hz, relatively high amplitude. 0
Changeux; Neuronal Man 68 Beta waves, waking state, eyes open, frequency more than double alpha waves, lower amplitude. 0
Changeux; Neuronal Man 69 EEG recordings -    alpha waves 10 Hz, awake and resting;    beta activity;    delta waves, slow, high-amplitude waves, slow-wave sleep;    REM sleep, paradoxical sleep, eyes move - (illustration from recording) 1
Changeux; Neuronal Man 69 Delta waves, slow, high-amplitude waves, (3-5 Hz, several hundred microvolts), slow-wave sleep. 0
Changeux; Neuronal Man 70 Deep sleep, delta waves, 3 to 5 Hz, amplitude several hundred microvolts 1
Changeux; Neuronal Man 70 REM sleep, intense electrical activity, brief bursts of high frequency, perhaps related to dreams. 0
Changeux; Neuronal Man 70 Alpha waves and delta waves have a repetitive form not suggestive of information. 0
Changeux; Neuronal Man 70 Beta waves, no obvious regularity; perhaps suggestive of information. 0
Changeux; Neuronal Man 72 Alpha rhythm may result from an autorhythmic activity in closed loops between cortical and thalamic neurons. 2
Changeux; Neuronal Man 72 The global electrical events recorded in the cerebral cortex,    electrical activity of individual neurons and glial cells,    including generation of impulses by the neurons,    propagation along axons,    transmission at synapses. 0
Changeux; Neuronal Man 109 In the hypothalamus and the brainstem,    dopamine synapses can be regarded as "pleasure" or "hedonic" synapses. 37
Changeux; Neuronal Man 111 Limbic system, inherited from primitive mammals. 2
Changeux; Neuronal Man 111 EEG recordings from various parts of the brain during orgasm.    Slow, high-amplitude waves similar to those in epilepsy appear, principally in the septum. 0
Changeux; Neuronal Man 112 Orgasm for man and for woman is the supreme ecstasy, intense waves of pleasure and emotion. 1
Changeux; Neuronal Man 113 Acetylcholine in the septum of a female provoked intense sexual pleasure, culminating in repeated orgasm. 1
Changeux; Neuronal Man 115 The human brain is characterized by the expanded development of the neocortex. The structures of the limbic system,    hypothalamus,    and brainstem have changed little. 2
Changeux; Neuronal Man 130 Ambiguous figure. Wine glass or Bikini? 15
Changeux; Neuronal Man 137 The mental object    is identified as the physical state    created by correlated, transient activity,    both electrical and chemical,    in a large population or 'assembly' of neurons    in several specific cortical areas. 7
Changeux; Neuronal Man 138 A 'concept' is a memory object that contains only a small sensory component, because it is the result of neuronal activity in association areas such as the frontal lobe (where multiple sensory or motor modalities are mixed) or in a large number of areas in different regions of the brain. 1
Changeux; Neuronal Man 138 The image is an autonomous and transient memory object,    not requiring direct interaction with the environment. 0
Changeux; Neuronal Man 139 Resonance    manifests itself by potentiation of firing, dissonance    by its extinction. 1
Changeux; Neuronal Man 142 When a synapse is stimulated repeatedly,    it habituates;    the number of quanta of neurotransmitter released decreases. 3
Changeux; Neuronal Man 143 Entry of calcium into the nerve terminal    may regulate the efficiency of the synapse    by increasing the probability    of the release of neurotransmitter. 1
Changeux; Neuronal Man 143 Desensitization 0
Changeux; Neuronal Man 146 Auditory hallucinations 3
Changeux; Neuronal Man 146 Hallucinogenic drugs, LSD, visual hallucinations 0
Changeux; Neuronal Man 147 Sleep lowers the level of consciousness, but is totally unrelated to death.    Sleep is an active process,    composed of a complex sequence of cerebral activities. 1
Changeux; Neuronal Man 147 Albert Hofmann synthesized LSD. 0
Changeux; Neuronal Man 147 LSD binds to the same sites as serotonin,    also binds to the receptor of dopamine. 0
Changeux; Neuronal Man 149 The reticular formation of the brainstem controls global aspects of cerebral functioning. 2
Changeux; Neuronal Man 154 Attention manages the relationship of the brain with the environment. 5
Changeux; Neuronal Man 156 Nuclei in the reticular formation participate in the fixation of attention. 2
Changeux; Neuronal Man 156 Dopamine neurons in the brainstem are concerned with the control of attention, in addition to their involvement in the 'pleasure synapses' that control motivation. 0
Changeux; Neuronal Man 157 Most drugs that attenuate the symptoms of schizophrenia are related to the dopamine receptor. 1
Changeux; Neuronal Man 158 Emotions involve neurons in the hypothalamus and the limbic system. 1
Changeux; Neuronal Man 173 Pleiotropism - genetics term used to designate the multiplicity of effects of a single mutation. 15
Changeux; Neuronal Man 180 Noam Chomsky in 1980s claimed that a genetically determined capacity of language specifies a class of humanly accessible grammar. 7
Changeux; Neuronal Man 197 Five stages in the embryonic development of the cerebral cortex from the wall of the neural tube. - (illustration) 17
Changeux; Neuronal Man 200 Mouse whiskers 3
Changeux; Neuronal Man 206 Once a nerve cell has become differentiated, it does not divide anymore.    A single nucleus, with the same DNA,    must serve an entire lifetime    for the formation and maintenance    of tens of thousands of synapses. 6
Changeux; Neuronal Man 206 Identical twins    develop from the division of the same fertilized ovum;    genetically identical. 0
Changeux; Neuronal Man 206 Human genome, ~20 thousand genes;    human cerebral cortex, ~1015 synapses. 0
Changeux; Neuronal Man 208 Variability in neural organization of identical twins. - (illustration) 2
Changeux; Neuronal Man 209 Consanguineous mice have a large number of their genes in common    due to inbreeding for fifty years or more;    compare individuals, same genome. 1
Changeux; Neuronal Man 213 Under an electron microscope, a growth cone looks somewhat like a tiny amoeba. 4
Changeux; Neuronal Man 215 When growth cones reach target, movements suddenly cease. Immobilized cone is transformed in a few hours into a nerve terminal, gradually takes the appearance of a mature synapse. 2
Changeux; Neuronal Man 215 Behavior of the growth cone, genetic cost is modest, great variability in the arrangement of the first contacts with the target; very little precision in the assembly of the network. 0
Changeux; Neuronal Man 215 Epigenetic mechanisms    tune it up,    create the final set of neural connections. 0
Changeux; Neuronal Man 227 Theory of epigenesis    by selective stabilization of synapses. 12
Changeux; Neuronal Man 227 Principal features of the anatomical and functional organization of the nervous system are preserved from one generation to another; determinism of a set of genes that make up the genetic envelope. 0
Changeux; Neuronal Man 227 During development, axonal and dendritic trees branch and spread exuberantly; redundancy is temporary; regressive phenomena rapidly intervene; neurons die; many dendritic and axonal branches are 'pruned'. 0
Changeux; Neuronal Man 227 Impulses travel through the neuronal network even at very early stages of formation. They begin spontaneously, but are later evoked by the interaction of the newborn with the environment. 0
Changeux; Neuronal Man 228 Hypothesis of epigenesis by selective stabilization. - (1) growth, (2) transient redundancy, (3) selective stabilization 1
Changeux; Neuronal Man 228 Epigenesis by Selective Stabilization, (1) growth, (2) transient redundancy, (3) selective stabilization, - (diagram) 0
Changeux; Neuronal Man 229 Evolution of the connective state of each synaptic contact    is governed by the signals received    on the mass of dendrites    on the postsynaptic cell. 1
Changeux; Neuronal Man 229 Activity of the postsynaptic cell regulates the stability of the synapse. 0
Changeux; Neuronal Man 229 Epigenetic development of neuronal network is controlled by the activity of the developing network. 0
Changeux; Neuronal Man 229 Selective stabilization of a particular set of synaptic contacts during the stage of maximum diversity. 0
Changeux; Neuronal Man 229 Variability    in patterns of connection    accounts for phenotypic variability    between isogenic individuals. 0
Changeux; Neuronal Man 233 Small number of genetic determinants with the genetic envelope explains how innervation develops. 4
Changeux; Neuronal Man 233 Cortical development is at least partially regulated by activity. 0
Changeux; Neuronal Man 235 Inactivity causes preservation of redundant connections. 2
Changeux; Neuronal Man 235 Cortical development  is subject to significant epigenetic regulation through nervous activity. 0
Changeux; Neuronal Man 235 Epigenetic regulation intervenes in the intrinsic differentiation of a given cortical area; development of a 'micro-organization'. 0
Changeux; Neuronal Man 235 Especially in humans, remarkable series of brain areas    specialized for 'cooperative understanding' in a social group;    language. 0
Changeux; Neuronal Man 236 90 percent of humans use the right hand for writing and difficult manual tasks. 1
Changeux; Neuronal Man 236 Negative' handprints    outlined on walls of caves of Cro-Magnon humans    are left hands    in 80 percent of cases. 0
Changeux; Neuronal Man 242 Development of the human brain continues long after birth. 6
Changeux; Neuronal Man 242 Most synapses    of the cerebral cortex    are formed after birth. 0
Changeux; Neuronal Man 244 Writing requires a long apprenticeship,    which is much easier for a child than for an adult. 2
Changeux; Neuronal Man 247 Experience, which is never the same from one individual to another, leads to a different neuronal and synaptic topology. 3
Changeux; Neuronal Man 247 Epigenesis    ensures the reproducibility of function    despite anatomical variations. 0
Changeux; Neuronal Man 248 Mental exercise,    either spontaneous or evoked,    contributes to the fine tuning of cerebral cortex connections. 1
Changeux; Neuronal Man 248 10 thousand or so synapses    per cortical neuron    are not established immediately. They proliferate in successive waves from birth to puberty in humans.    With each wave there is a transient redundancy and selective stabilization.    The result is a series of critical periods when activity exercises a regulatory effect. 0
Changeux; Neuronal Man 249 Growth of axonal and dendritic trees    is innate;    the selective stabilization of synapses defines acquired characteristics. 1
Changeux; Neuronal Man 249 Intimate association of growth and epigenesis and their alternation over time. 0
Changeux; Neuronal Man 249 System becomes more and more ordered    as it receives instructions from the environment. 0
Changeux; Neuronal Man 249 Epigenetic selection acts on preformed synaptic substrates.    0
Changeux; Neuronal Man 249 To learn is to stabilize synaptic combinations    and to eliminate the surplus.
Changeux; Neuronal Man 251 Observe chromosomes of a human under the microscope, Blood sample is taken and white cells cultured, mitosis, chromosomes separate, stained and identified. 2
Changeux; Neuronal Man 277 Humans    are born with a brain    whose maximum number of cells    is already fixed. 26
Changeux; Neuronal Man 278 Diversification through recombinations within neuronal assemblies,    followed by selection through resonance. 1
Changeux; Neuronal Man 281 Epigenesis that follows birth;    activity in the developing network    governs the stabilization of some synapses    and the elimination of others. 3
Changeux; Neuronal Man 282 Nervous system is unusual in that its total number of neurons is fixed at birth. 1
Changeux; Neuronal Man 282 Neurons that are destroyed after birth are never replaced.    0
Changeux; Neuronal Man 282 Axons and dendrites    preserve a remarkable capacity to regenerate    even in the adult.
Changeux; Neuronal Man 282 Brain of Homo sapiens probably differentiated in the African plains,    in populations of a few hundred thousand individuals. 0
Changeux; Neuronal Man 282 Transient redundancy followed by selective stabilization. 0
Changeux; Neuronal Man