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PubMed1981

Neurobiological and genetic aspects of the etiology of alcoholism.

In contrast to humans, most animals will not voluntarily consume alcohol to the point of intoxication nor to the point of development of tolerance and physical dependence. Since there is good evidence for a genetic component to human alcoholism, we explore the possibility that the presence of alcohol in the environment during human evolution has contributed to this difference in behavior from that observed in lower animals. We then review the biologic basis for genetic influences on various aspects of alcohol-related behaviors in both humans and lower animals. Thus, the evidence for genetic influences on rate of alcohol metabolism, preference, central nervous system depressant effects. tolerance, and dependence are briefly reviewed. The technique of selective breeding for alcohol-related behavior is described and compared to the process of natural selection that may be occurring in the human population.

Acetaldehyde↗
PubMed1980

A peptide potpourri.

Explore the source record for details and available documents.

Biological Evolution↗
PubMed1980

[Comparative volumetric analysis of the principal subdivisions of the telencephalon in saurian reptiles].

The volumetric measure of the main subdivisions of the telencephalon has been carried on 24 species of Lizards and 2 species of Snakes. The studied structures are termed as follows: main and accessory olfactory bulbs, medial cortex (M 1 and M 2), dorsal cortex (D 1, D 2 and D 3), lateral cortex (L), Septum, Tuberculum olfactorium, dorsal and ventral striatum, amygdala and nucleus sphaericus. The analysis of the datas makes use of the SNEL L's formula which relates the volume of the various telencephalic subdivisions (V) to the somatic weight (S): V = k x S alpha. Each alpha value is compared to the value of the coefficient of allometry (A) of the whole brain. The evolutive (phylogenetic) growth of a structure is said fast (or slow) when its corresponding alpha value is higher (or lower) than the encephalic A value. At the cortical level such analysis shows the progressive nature of the dorsal cortex. A partition of the sample into Lacertomorpha (14 species) and Dracomorpha (10 species) (in agreement with the NORTHCUTT'S definition of his Type I and Type II Lizards) corroborates this cortical detail, more distinctly with the second group as well (especially for the D 2 portion). Moreover the high number of progressive structures among the Dracomorpha leads to consider this group as phylogenetically the most advanced in the Order of Lizards. The somatic indices are calculated according the allometric characteristics of the Reference Lizards. The judicious choice of some species allows to show how the development of a biological function may be expressed by the values of the indices of the related structures. For examples: dorsal cortex, dorsal striatum and mode of locomotion; olfactory bulbs, lateral cortex, part M 1 of the medial cortex and olfactory system; D 3 subdivision of the dorsal cortex and visual performances. The duality between Lacertomorpha and Dracomorpha is therefore corroborated by significant differences found for the various indices of a great number of telencephalic subdivisions. It leads moreover to find, grosso modo, two functional types of Lizards: moving-on-the-ground and wellsmelling (mainly Lacertomorpha) on the one hand, arboreal and with a fine vision (mainly Dracomorpha) on the other hand. The isoponderal percentages take an useful illustration of these results; it allows to establish the telencephalic pattern of a standard Lizard in which the pallium keeps the larger part (42%); in the pallium itself, the M 1 subdivision of the medial cortex has the most important percentage, a little more than the D 2 part of the dorsal cortex. A comparative study carried on 2 Snakes gives for Boa constrictor the lowest values of the indices, for almost all the structures. In return Natrix natrix stays, for a great number of structures, close to the level of the legless Lizards; this last result confirms distinctly the two levels of telencephalization already found in Snakes (PLATEL, 1976 a).

Amygdala↗
PubMed1994

Comparative anatomy of cranial nerve motor nuclei: with a comment on evolution of the craniofacial region.

Changes of cranial nerve nuclei are investigated at three crucial points of phylogenesis in frogs, lizards and rats. Profound changes can be observed in the trigeminal and facial motor nuclei parallel to transformation of the primary mandibular joint into the secondary mandibular joint. New muscles appear for mastication and facial expression and they are innervated by new types of neurons. The muscular tongue appears first in tetrapods coinciding with terrestrial life. It can be shown that an entirely new type of neuron develops at the medullospinal junction for the innervation of the intrinsic tongue muscles. These muscles and their neurons are not homologous to somatic muscles and spinal cord neurons. The external eye muscles and their innervation are present from the early craniates through apes in virtually the same pattern of organization. They evolved coincidently with the head and are not homologous to any other structures. It is concluded that if we accept the 'neogenesis' view in head evolution, all contradictions imposed, by the 'segment theory', upon the interpretation and classification of cranial nerve nuclei can be circumvented.

Animals↗
PubMedDate not supplied

[Consciousness].

"Consciousness" is the feeling that each individual has of his own existence (self-awareness) and also the state which permits him to perceive his environment (consciousness and wakefulness). These two types of consciousness, apparently quite different, are in fact the two converging stems of the perceptions that the nervous system provides to the organism. To explain this better, it is necessary to refer to the evolution of the nervous system organization among the species and to imagine what perception the nervous system provides at each stage of this evolution, or in each species harbouring a nervous system corresponding to a given stage. At the beginning, the role of the nervous system is to protect the organism and only by an automatic and reflex organization. It corresponds to an unconscious alertness which permits to perceive the environment; it is the prefiguration of the future consciousness. Self-awareness seems to appear with the centrencephalic and limbic structures which are the highest part of the nervous system in the inferior mammals and the central part in man. At this stage, acquisition memory and affectivity with its different manifestations (emotions, mood, pain...) are established. This kind of consciousness is difficult to imagine since it is only sensorial and affective. Mental consciousness appears with the mental activity in the cerebral hemispheres. It is more than likely that it exists in the superior mammals though it is impossible to imagine what it corresponds to. It reaches the highest development in the man in whose the frontal lobes have the largest extent. Speech is the most striking figure of this development. At each stage of the evolution, consciousness expresses the nervous system activity, centered on a perception, the level of which corresponds to the improvements occurring at each stage and superadded to the previous ones. Hence it is obvious that consciousness has no specific center or pathway. It relies upon structures that participate in triggering and regulating the nervous activity and that utilize the particular centers of perception and analysis. These structures are: the reticular formation and the diffuse thalamic system.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Evolution of multiple areas and modules within neocortex.

There is compelling evidence that the number of cortical areas is variable across species, ranging from the order of 10 to 20 in species with little neocortex to perhaps a hundred or more in humans. The first mammals had few areas, and more fields evolved in several lines of descent. There are several general possibilities for how new cortical areas emerged in evolution, including the gradual differentiation of one area from another, the addition of new cortical tissue that became invaded by axons from other structures to create new fields, and the sudden duplication of existing areas as a result of mutation. A specific version of a "gradual differentiation" theory is presented. New areas might emerge as a result of a process in which classes of inputs to an area first segregate into modular groups of neurons, and then these modules coalesce to ultimately form totally separate populations. All stages allow expected functions to be mediated, and there might be different functional advantages for each stage. Thus, stages may be stable and change is not inevitable. As a result, all stages are represented in the organizations of existing fields of extant mammals.

Animals↗
PubMedDate not supplied

[The information-energy concept of the origin of the psyche].

An attempt is made to understand the origin of psyche on the basis of natural sciences as a result of biological evolution. Organization and control of the artificial systems is based on purely informational, or formal interaction, while in the living organisms the basis is informational-energetic, or conceptual interaction. This type of interaction is the basis of self-organization of the living systems at all levels. It is suggested that the principle of self-organization is crucial for emergence of mind.

Animals↗