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PubMed1976

Neuronal circuits involved in learning: the use of modifiable synapses in the simulation of behavior.

Our present knowledge of brain structure and function requires that any model of neuronal circuitry designed to account for learning must satisfy three conditions. It must (1) meet economy restrictions on the number of cells in the brain, (2) use the same set of cells to account for a number of different behaviors, and (3) not require a detailed embryological specification of its connections. Previously published models have failed to meet one or more of these conditions. In this paper, a model is presented which does satisfy them, and in doing so accounts in detail for classical conditioning, operant conditioning, and other learning tasks. The model employs the types of synapses proposed by Burke and Hebb in simple modular circuits as a means of providing independent storage of information at each modifiable synapse.

Animals↗

PubMed1980

The fiber connections of the temporal lobe with emphasis on the rhesus monkey.

The temporal lobe has three functionally distinct areas which have minimal interconnections within the lobe, but extensive connections with other parts of the brain. The superior temporal gyrus contains primary and association auditory areas. Inferotemporal cortex is exclusively a visual association area. The temporal pole is involved in social behavior. In addition, the superior temporal sulcus functions as a sensory integration area. From a review of the literature, a schema is proposed for organizing the reciprocal connections of the three functional areas into a series of loops which follow both cortical and subcortical routes. The afferent and efferent connections of the temporal lobe, phylogenesis, and deficits from lesions are discussed.

Amygdala↗

PubMedDate not supplied

Tubulins in Trichomonas vaginalis: molecular characterization of alpha-tubulin genes, posttranslational modifications, and homology modeling of the tubulin dimer.

We have isolated and analysed an alpha-tubulin-encoding gene (atub1) in an early-diverging eukaryote, Trichomonas vaginalis. The complete atub1 open reading frame included 1.356 bp encoding a polypeptide of 452 amino-acyl residues. A second alpha-tubulin gene (atub2) was amplified by PCR using primers derived from consensus alpha-tubulin amino acid sequences. Both T. vaginalis alpha-tubulin sequences showed high identity to those described in other parabasalids (94.4%-97.3%), and exhibited a high degree of similarity to sequences from Metazoa (such as pig brain) and diplomonads (such as Giardia). Despite large evolutionary distances previously observed between trichomonads and mammals, the three-dimensional model of the T. vaginalis tubulin dimer was very similar to that of pig brain. Possible correlations between alpha-tubulin sequences and posttranslational modifications (PTMs) were examined. Our observations corroborated previous data obtained in T. vaginalis using specific anti-PTMs antibodies. As described in the related species Tritrichomonas mobilensis, microtubules are likely acetylated, non-tyrosinated, glutamylated, and non-glycylated in T. vaginalis. Evolutionary considerations concerning the time of appearance of these tubulin PTMs are also discussed since trichomonads are potentially one of the earliest diverging eukaryotic lineages.

Amino Acid Sequence↗

PubMed1983

Human paleontological evidence relevant to language behavior.

The paleoneurological evidence for human language origins and other cognitive activities is tantalizing, but uncertain given the often incomplete, fragmented, and eroded cranial portions of our fossil ancestors. Nevertheless, both the Taung and A.L. 162-28 endocranial portions, attributed to the earliest-known hominids (i.e. Australopithecus afarensis and africanus) evidence some cerebral organization beyond a typical pongid pattern, in that there appears to be a reduction in primary visual striate cortex, and thereby a relative increase in posterior and inferior parietal cortex. At 1.8-2.0 million years, there is clear fossil evidence for a Homo lineage showing a more modern and enlarged third inferior frontal convolution, expanded brain size (e.g., 750+ ml), and strong cerebral asymmetries identical to those known for modern Homo sapiens. Additional evidence of sexual dimorphism in the modern human corpus callosum, in which the posterior splenial portion is larger in females, taken in conjunction with known clinical and psychological evidence relating to cognitive task specialization, suggests that this dimorphism represents a biological heritage from past selection pressures for a dichotomous but complemental social behavioral set of adaptations to favor a division of sexual labors compatible with nurturing offspring with delayed maturation, prolonged growth, and a longer period of postnatal neural plasticity.

Biological Evolution↗

PubMed1994

Cloning of human and mouse brain cDNAs coding for S1, the second member of the mammalian elongation factor-1 alpha gene family: analysis of a possible evolutionary pathway.

We previously reported the cloning of a rat S1 cDNA whose deduced amino acid sequence shares high similarity (92%) with that of mammalian elongation factor-1 alpha (EF-1 alpha), a protein involved in the binding of aminoacyl-tRNA to the ribosome during peptide synthesis. We report here the isolation of a full-length cDNA from a mouse brain library and a partial-length cDNA from a human hippocampus library which share extensive sequence similarity to rat S1 cDNA. We show that, as with mammalian EF-1 alpha S, the predicted primary amino acid sequences of rat, mouse, and human S1 are almost identical, except for one conservative substitution. These results indicate that mouse and man contain a second member of the EF-1 alpha gene family, the S1 gene. They also suggest that our result obtained in rat may be extrapolated to mouse and man.

Amino Acid Sequence↗

PubMedDate not supplied

[Evolutionary concepts of affective disorders].

Mood may be considered the module of the human mind, which has evolved to tune the activity ofthe organism to the specific environmental conditions in a better way. In some cases depression may be adaptive, for example in aborting the activity associated with too many obstacles. At the same time hypomania may be related to the capability of mobilising the organism to gain many resources in a short period of time. Severe mood disorders may be related to the genetic variants, eg. of the serotonin transporter or brain-derived neurotrophic factor, which in several situations may give some evolutionary advantage. Affective temperaments, observed in the relatives of patients with affective disorders may be associated with some benefits in the social life. The relationship between early adversities and adult depression may be related to the phenomenon of the stress axis programming, which has deep evolutionary roots. Some infectious factors may cause behaviours similar to the affective symptoms, which may increase their reproductive success. The evolutionary perspective, which is complementary to the current etiopathogenic theories may help in understanding, why genes and traits which

Affective Symptoms↗

PubMed1989

Characterization of a monoclonal antibody directed against a sulphoglycolipid that is evolutionarily conserved and developmentally regulated in rat brain.

Monoclonal antibodies (MABs) have been raised against acidic glycolipids extracted from the electric organ of Torpedo marmorata. One of these, designated L9, appears to recognize acidic glycolipids in adult T. marmorata electric organ, electromotor nerves and brain, adult rat sciatic nerve, and in embryonic and neonatal rat brain, starting at embryonic day (ED) 15 and disappearing by the 20th day of post-natal life. The epitope is present in growth cones isolated from 4-day-old rats; its proportion relative to total gangliosides is, however, no higher than that found in whole neonatal brain membranes. Desialidation of the acidic glycolipid fraction modifies neither the immunoreactivity nor the RF value following thin-layer chromatography (TLC) of the antigen; it is concluded that the antigen is not a ganglioside. The MAB, HNK-1, recognizes the L9 antigen. Both HNK-1 and L9 recognize a sulphoglycolipid of the same RF in TLC. The function of the L9 antigen is not known but its evolutionary conservation, presence in growth cones and its developmental regulation in the mammalian central nervous system indicate that it plays an important role in nervous system maturation.

Animals↗

PubMed2001

Evolutionary psychology and the brain.

The human brain is a set of computational machines, each of which was designed by natural selection to solve adaptive problems faced by our hunter-gatherer ancestors. These machines are adaptive specializations: systems equipped with design features that are organized such that they solve an ancestral problem reliably, economically and efficiently. The search for functionally specialized computational adaptations has now begun in earnest. A host of specialized systems have recently been found, including ones designed for sexual motivation, social inference, judgment under uncertainty and conditioning, as well as content-rich systems for visual recognition and knowledge acquisition.

Adaptation, Psychological↗

PubMed2001

The relevance of hierarchies, territories, defeat for depression in humans: hypotheses and clinical predictions.

BACKGROUND: Hierarchical and territorial behaviour are widespread in animals and humans. The consequences of defeat have been linked to depression in humans. However, hierarchical and territorial behaviours are not mentioned in ICD10 or DSM1V. I therefore investigated the coverage in relevant textbooks. METHOD: I searched the indices of books on Animal Behaviour, General Psychology and General Psychiatry for entries on Hierarchy, Territory and Dominance. RESULTS: A paradox is revealed. Hierarchical and territorial behaviour are widespread in both animals and humans but are neglected in textbooks of human behaviour and mental problems. Four hypotheses are put forward to explain this paradox and explore its implications. 1. That hierarchical and territorial behaviours evolved before human consciousness. They are available to consciousness but not in the forefront of awareness. 2. That human hierarchical and territorial behaviour are overlaid by a cultural veneer of manners, which conceal the true state of affairs. 3. That humans have internal, mental, hierarchical aims in addition to external physical hierarchical aims. 4. That failure to achieve internal hierarchical aims may produce diminution of well being and changes in behaviour by the same biological mechanisms that are active in external hierarchical defeat. Three testable predictions follow from these hypotheses. 1. That there are common genetic factors and similar patterns of brain activity in homologous structures during hierarchical and territorial behaviour in man, primates and lower vertebrates. 2. That brain structures involved in external hierarchical conflict, consciousness and imagery will be active during internal hierarchical conflict. 3. Defeat of internal hierarchical aims produce depressed mood and satisfying alternative hierarchical aims are protective. Case examples are given to illustrate the existence of, and the consequences of defeat on, internal hierarchies. LIMITATIONS: These hypotheses and predictions are theoretical and require confirmation or refutation by neuroimaging and prospective studies. CONCLUSIONS: A neglect of human hierarchical behaviour by clinicians is suggested and discussed. The concept of internal hierarchies, if confirmed, may throw light on human striving, the emotions of defeat and the therapy of depression.

Adult↗

PubMed1986

Multiple forms of gonadotropin-releasing hormone in amphibian brains.

Several forms of gonadotropin-releasing hormone (GnRH)-like molecules were found in brains of both anurans (frogs) and urodeles (salamanders). The presence of the mammalian-like GnRH molecule was confirmed by HPLC and cross-reactivity studies. Small amounts of salmonid-like GnRH molecules in the brains of frogs (Rana pipiens, Hyla regilla) and salamanders (Taricha granulosa, Ambystoma gracile) were detected by comparing the HPLC chromatographic pattern and immunological reactivity of the brain extracts with native trout and synthetic salmon GnRH. This nonmammalian form of GnRH in the amphibian brain is similar and perhaps identical, at least by indirect evidence, to a form of GnRH reported earlier to be in sympathetic ganglion, retina, chromaffin tissue, and tadpole brain. If two of the amphibian GnRH molecules prove to be mammalian and salmon GnRH, then it is likely that two separate genes in amphibians code for the distinct primary structures of the molecules. The most parsimonious interpretation of the presence of both mammalian- and salmon-like GnRH in anurans and urodeles is that a common phylogenetic ancestor also possessed the two forms of GnRH. Thus the mammalian form of GnRH may well have been present in labyrinthodont amphibians. Independent of evolutionary origin, the functions of the different GnRH molecules in amphibians are unknown.

Ambystoma↗

PubMedDate not supplied

[The dominant and neurodarwinism].

Lately, the trends analysing the traits of likeness between the evolutionary process, immune reactions and brain activity was called as "neurodarwinism" (G. Edelman). It has been established that pre-existed diversity of the material to be selected is the main condition of successful adaptation of the living organism to unknown future. The review of the data obtained in the course of studying the dominant by V. S. Rusinov's school shows that namely the dominant mechanism does ensure the variety of neuronal and behavioural assortment from which new adaptive behavioural acts are formed. This statement allows to consider further theoretical and experimental study of the dominant phenomenon as one of the priority and promising trends of the modern neurobiology.

Animals↗

PubMed2000

What is the brain?

From a structural perspective, there are ten basic parts of the vertebrate CNS that are almost universally agreed upon. These parts have been grouped in at least five different ways corresponding to five different theories about its basic plan or architecture. Two classical models that remain popular today are derived from (1) comparative anatomy and the body's segmental organization, and (2) comparative embryology and the neural tube's transverse and longitudinal organization. A new approach is concerned with deciphering the genetic program that assembles the nervous system during embryogenesis; how it will correspond to the other models remains to be determined. The simplest current model to explain the organization of the mammalian nervous system involves a segmental trunk that mediates reflex sensory-motor functions, and suprasegmental cerebral hemispheres and cerebellum.

Animals↗

PubMed1981

Evolutionary aspects of "brain-gut peptides": an immunohistochemical study.

Phylogeny of biogenic peptides and their source cells was studied by immunohistochemistry and electron microscopy. The distribution of the peptide containing neurons and paraneurons in the brain and in the gastroenteropancreatic endocrine system was depicted, especially in the bullfrog as the representative of deuterostomia and in the cockroach and some other insects as the representatives of protostomia. Stress was given to: (1) calcitonin-immunoreactive neurons in bullfrog hypothalamus and PP-reactive neurons in the cockroach protocerebrum as instances of transmissional-hormonal partition of a neuropeptide, (2) open-type endocrine cells in the gut structurally and functionally common to the protostomia and deuterostomia, and (3) phylogeny of the prohormones with special reference to big gastrin and proglucagon (glicentin).

Animals↗

PubMed1987

Tubulinlike protein from Spirochaeta bajacaliforniensis.

Tubulin proteins are the fundamental subunits of all polymeric microtubule-based eukaryotic structures. Long, hollow structures each composed of 13 protofilaments as revealed by electron microscopy, microtubules (240 angstroms in diameter) are nearly ubiquitous in eukaryotes. These proteins have been the subject of intense biochemical and biophyiscal interest since the early 1970s and are of evolutionary interest as well. If tubulin-based structures (i.e., neurotubules, mitotic spindle tubules, centrioles, kinetosomes, axonemes, etc.) evolved from spirochetes by way of motility symbioses, tubulin homologies with spirochete proteins should be detectable. Tubulin proteins are widely thought to be limited to eukaryotes. Yet both azotobacters and spirochetes have shown immunological cross-reactivity with antitubulin antibodies. In neither of these studies was tubulin isolated nor any specific antigen identified as responsible for the immunoreactivity. Furthermore, although far less uniform in structure than eukaryotic microtubules, various cytoplasmic fibers and tubules (as seen by electron microscopy) have been reported in several types of prokaryotes (e.g., Spirochaeta; large termite spirochetes; treponemes; cyanobacteria; and Azotobacter. This work forms a part of our long-range study of the possible prokaryotic origin of tubulin and microtubules. Spirochetes are helically shaped gram-negative motile prokaryotes. They differ from all other bacterial in that the position of their flagella is periplasmic: their flagella lie between the inner and outer membranes of the gram-negative cell wall. Some of the largest spirochetes have longitudinally aligned 240 angstrom microtubules. Unfortunately, in spite of many attempts, all of the larger spirochetes (family Pillotaceae) with well-defined cytoplasmic tubules and antitubulin immunoreactivity are not cultivable. However, a newly described spirochete species (Spirochaeta bajacaliforniensis) possessing cytoplasmic fibers displays antitubulin immunoreactivity in whole-cell preparations. Since preliminary observations suggested that Spirochaeta bajacaliforniensis proteins may be related to eukaryotic tubulins, their characterization was undertaken. Brain tubulin can be purified by utilizing its ability to polymerize at warm temperatures and to depolymerize in the cold. After several cycles of sedimentation and redissolution the microtubule fraction is comprised of 75% tubulin and 20% high molecular mass microtubule-associated proteins (MAPs). In this paper we report that components of cell lysates, prepared from a spirochete that contains cytoplasmic fibers (Spirochaeta bajacaliforniensis), also exhibit the property of temperature-dependent cyclical sedimentation. Additionally we report the identification and characterization of the polypeptide responsible for cross-reactivity with antitubulin antiserum.

Animals↗

PubMed1994

Hybridization of matrix-bound MM-creatine kinase with BB-creatine kinase and arginine kinase.

Dimeric rabbit muscle creatine kinase (MM-CK) was bound to CNBr-activated Sepharose 4B by one of its subunits (MM-CKA). Treatment of MM-CKA with guanidine hydrochloride released the unbound subunit to yield the matrix-bound monomer (M-CKB). M-CKB recombined with dissociated MM-CK soluble subunits to reconstitute a matrix-bound dimer (MM-CKC). M-CKB also associated with dissociated subunits of BB-CK from crude extracts of rabbit brain and of arginine kinase from sea cucumber muscle (MM-AK) to form the matrix-bound heterohybrids MB-CKC and M-CK/M-AKC, respectively. Guanidine hydrochloride gradient elution studies showed that MM-CKA, MM-CKC and MB-CKC were all dissociated at the same concentration of the denaturant (0.96 M), while the M-CK/M-AKC heterohybrid was less stable, dissociating at 0.5 M. The specific interaction between subunits of echinoderm and mammalian phosphagen kinases to form a hybrid enzyme of dual substrate specificity supports the view that these enzymes had a common evolutionary origin.

Animals↗

PubMed1991

Neuronal branching patterns and the economy of cortical wiring.

Keeping the volume of connections in the cortex as low as possible may be an important evolutionary constraint on the design of the brain. Much as an engineer tries to arrange the components of a computer in such a way as to give efficient wiring, so the brain may have evolved a layout of neuronal types which gives an economical use of axonal 'wiring'. One key difference between computer and brain is that connections in the brain take the form of elaborate branching structures. It is argued here that certain features of cortical mapping, such as the stripes and patches seen within cortical areas, may be adaptations which allow efficient wiring by such structures. Some simple calculations are given to support this, using as models for axonal arbors certain branching patterns which give a low volume of wiring. In particular, it is shown that a pattern of stripes can give economical wiring when axon diameters follow a law dp = dp1 + dp2 with p greater than 4, where d1 and d2 are the diameters of the daughter branches and d that of the parent.

Animals↗

PubMed1981

The emergence of man: information from protein systems.

Protein amino acid sequences are not directly informative about the emergence of man from his immediate primate ancestry. But this could be because too little attention has been given to protein systems most relevant to the progress of hominization, those that, through their cell-surface action or enzymatic control of biosynthesis of other key proteins or hormones, can modulate the course of cell and tissue development, and so determine changes in tooth architecture, bone and tissue structure, brain and nerve cell development, etc. There are also the histones and other proteins associated with DNA in the genetic material, which have some modulating influence on gene expression. The whole process of carrying information from the genetic material to a species-reproducible morphology is through a cascade of multiple interlocking systems involving proteins at every turn. It is through changes in balance within these systems, and subsequent selection pressures, that the modulations of primate morphology and behaviour that constitute hominization have proceeded, and the process must be understood in terms of cytobiochemistry to give a fully detailed information of the evolving human genome.

Amino Acid Sequence↗

PubMed1993

Sex pheromone systems in goldfish: comparisons to vomeronasal systems in tetrapods.

Most amphibians, reptiles and mammals possess a well defined dual olfactory system comprised of separate neural pathways that regulate different olfactory functions. One pathway originates in the nasal cavity and gives rise to what is commonly referred to as the main olfactory system. The other pathway originates in the vomeronasal organ (VNO) and gives rise to the accessory olfactory system. Functionally, the main olfactory system is thought to subserve, olfactory-mediated tasks such as feeding and grooming, while the accessory olfactory system is believed to be primarily involved in mediating behavioral and physiological responses to sex pheromones. Traditionally, it has been difficult to address whether teleosts possess any components of the vomeronasal system, since they generally do not meet the criteria used to identify vomeronasal systems in other vertebrates. Previous conclusions that the nasal epithelia of fish is olfactory and not vomeronasal in nature are based on observations that teleosts lack a separate VNO-like chemosensory structure and an anatomically distinct accessory olfactory bulb. However, because sex pheromones have been identified in the goldfish, it is now possible to compare the neural substrates that regulate pheromone-induced responses in teleosts to those that mediate similar responses in other vertebrates. The olfactory system in goldfish is particularly well suited for such comparisons, because it comprises anatomical and functional subdivisions that resemble those associated with the main and accessory olfactory systems in tetrapods. The olfactory pathways that mediate endocrine and behavioral responses to sex pheromones in goldfish are described and then compared to the main and accessory olfactory systems of tetrapods. In making these comparisons, a number of similarities become apparent. First, the olfactory pathways that regulate responses to sex pheromones in goldfish are different from those that serve a more general olfactory function. Second, these functional differences appear to be subserved by separate and anatomically distinct olfactory tract projections to the brain. Third, the lateral olfactory tracts and their central projections in goldfish appear to serve a function analogous to that of the main olfactory system, while the medial olfactory tracts and their central projections comprise a pathway remarkably similar to the vomeronasal-accessory olfactory system. These findings suggest that teleosts may possess functional correlates of tetrapod vomeronasal systems, but in a form that has yet to be recognized. If so, medial olfactory tract projections in goldfish may be evolutionarily conserved and expressed in tetrapods as the vomeronasal system, or the medial olfactory tract projections may be new pathways that have evolved to serve the same function.

Animals↗