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At least 1,081 records · Page 60Linked to original sources
PubMed1987

Alpha-actinin and spectrin have common structural domains.

The alpha- and beta-subunits of spectrin are made of repeated homologous units of 106 residues. In the recently reported partial sequence of the chicken non-muscle alpha-actinin, a repetitive sequence homologous to the internal repeat in spectrin occurs several times. Both spectrin and alpha-actinin are components of the cytoskeletal network, the integrity of which is based on multiple and complex interactions. We suggest that the shared domain structure indicates common structural principles or interactions of spectrin and alpha-actinin and reflects their common evolution.

Actinin↗
PubMed1982

The TPc, the avian substantia nigra: pharmacology and behavior.

The nucleus tegmenti pedunculo-pontinus, pars compacta (TPc) may be the avian analogue of the mammalian substantia nigra (SN). The analogy is suggested by both comparative neuroanatomical and neurohistochemical observations. To test the proposed analogy certain drugs (agonists or antagonists of putative transmitters that modulate the dopaminergic and GABAergic systems in rat) were injected into the TPc of the pigeon and the behavior effects observed. Muscimol (a GABA agonist) injected into the caudal TPc induced contralateral rotation and postural asymmetries. Pretreatment with subcutaneous injections of apomorphine hydrochloride enhanced and haloperidol suppressed the rotatory response, while the postural asymmetries were not altered by either drug. Muscimol injected into the rostral TPc induced contralateral rotation, marked ataxia, and postural asymmetries, particularly the head and neck, legs and wings. Whereas apomorphine (subcutaneous injection) was without effect on the rotatory response to muscimol, haloperidol suppressed the rotatory response. Neither drug effected the postural asymmetry. Following drug injections into either the pigeon TPc or the rat SN the behaviors induced in both bird and rat suggest that the TPc and SN are analogous.

Animals↗
PubMedDate not supplied

Randomness, redundancy and repair: roles and relevance to biological aging.

In this paper, some of the key findings of the last decade will briefly be surveyed and, where possible, be related to two separate computer simulation models which have been designed to determine the validity of certain widely accepted dogmas and to define the limits and restrictions imposed by attrition of or ambiguity of information retrieval from information storage systems. It is known: (1) that the idealized rectangular survival curve in an "ideal" environment is an extrapolation that is inconsistent with reasonable primary assumptions; (2) that loss of redundant copies of functional "housekeeping" genes may well be a dominant contributor to human senescence; and (3) that redundancy, particularly of informational storage, not only confers greater stability on an organism in dealing with stochastic or programmed age changes, but that it also provides a means through which a more optimized use of informational storage space may be attained.

Aging↗
PubMed1992

Could an autonomous syntax module have evolved?

Darwinian evolution necessitates a contribution to reproductive fitness. Recent studies of aphasia and Parkinson's disease show that functional syntactic ability involves neural structures that also are involved in speech motor control and nonlinguistic cognition. The evolution or presence of an autonomous syntax module is, therefore, implausible.

Aphasia, Broca↗
PubMed1984

Collateralization in the spinothalamic tract: new methodology to support or deny phylogenetic theories.

Components of the spinothalamic system that ascend in the anterolateral funiculus are reviewed. The presence of collateralization in this system in mammals is discussed with regard to theories of the phylogenetic development of pathways. The major theory investigated suggested that collateralization is an intermediate stage between a multisynaptic pathway and a direct non-collateralized lemniscus. The evidence and theories are reviewed. Methods for confirming or rejecting this theory are discussed. The literature reporting ascending spinal projections for non-mammalian vertebrates is reviewed. Certain reptiles have projections analogous to both the mammalian neospinothalamic and paleospinothalamic tracts. The presence of spinothalamic projections in elasmobranchs and amphibians is still controversial. Confirmation of earlier reports of projections in salamander and dogfish shark based on degeneration techniques have not been done. In addition, results from too few species of these classes have been reported. However, it is possible that paleospinothalamic connections are present in some species (e.g. salamander, nurse shark) and not in others (e.g. frog, dogfish shark) of the same class. Spinothalamic projections have not been reported for teleosts. A plea for new research in this area is made.

Animals↗
PubMed1995

Theory of mind: evolutionary history of a cognitive specialization.

Traditional analyses of the evolution of intelligence have emphasized commonality and continuity among species. However, recent research suggests that humans might have specialized in a particular kind of intelligence that is related to understanding mental states such as desires, intentions and beliefs. Data indicate that the ability to reflect on one's own mental states, as well as those of others, might be the result of evolutionary changes in the prefrontal cortex. Behavioral studies in children and chimpanzees reveal both similarities and striking differences in the developmental pathways that lead to theory-of-mind capacities. Humans and great apes share many ancient patterns of social behavior, but it is too early to be certain if they interpret them in the same manner. Humans might have evolved a cognitive specialization in theory of mind, forever altering their view of the social universe.

Animals↗
PubMedDate not supplied

Evolution of the red nucleus and rubrospinal tract.

A red nucleus, defined by its relative position in the tegmentum mesencephali, its contralateral rubrospinal or rubrobulbar projections and by crossed cerebellar afferents, is found in terrestrial vertebrates and certain rays. A crossed rubrospinal tract occurs in anurans, limbed urodeles and reptiles, birds and mammals, but is apparently absent in boid snakes, caecilians and sharks. A distinct rubrospinal tract is found in certain rays which use their enlarged pectoral fins for locomotion. A crossed tegmentospinal tract, possibly a rubrospinal tract, is found in lungfishes. Although evidence was presented for a rubrospinal tract in more advanced snakes, the available experimental data in lower vertebrates suggest that the presence of a rubrospinal tract is related to the presence of limbs or limb-like structures. In the connectivity of the red nucleus in terrestrial vertebrates, 'levels' of complexity can be distinguished, paralleled by the development of the cerebellum. These 'grades of organization' are probably related to the type of motor performance the particular terrestrial vertebrates are capable of.

Afferent Pathways↗
PubMedDate not supplied

On the presence of nucleus ruber in the urodele Salamandra salamandra and the caecilian Ichthyophis kohtaoensis.

The presence of nucleus ruber in urodeles and caecilians (amphibia) was investigated. For that purpose, horseradish peroxidase was applied to the rostral spinal cord, the medulla oblongata at various levels and the dorsolateral funiculus. Whereas Salamandra salamandra possesses a rubrospinal tract, it is absent in the limbless caecilian Ichthyophis kohtaoensis.

Amphibians↗
PubMed1984

The pharmacology of molluscan neurons.

It is commonly accepted that the basic physiological properties of the neurons as well as the nature of transmitter substances have remained relatively unchanged through evolution, while brain size and neuron number have greatly increased. Among invertebrates the molluscs, due to the large size of their neurons and lesser complexity of the neural networks controlling specific behavior, have proved to be especially useful for studying elementary properties of single neurons, network organization as well as various forms of learning and memory. The study of putative neurotransmitters has indicated that molluscs use the same low molecular-weight substances and peptides or their metabolites and cyclic nucleotides as transmitters and second messengers as the other species of various phyla. At the same time the receptors of neurotransmitters were found to have certain characteristic properties in the molluscs. The large molluscan neurons have permitted the isolation of individual identifiable nerve cells, and the subsequent analysis of quantities of the transmitters and their metabolic enzymes. These studies have demonstrated that single neurons frequently can contain more than one putative neurotransmitter. It can be expected that this model will contribute to an understanding of the role of multiple transmitters within a single neuron assuring the plasticity of the nervous system. The cellular mechanisms of plasticity have been demonstrated first in molluscan nervous systems. It was proved in identified Aplysia neurons that the same transmitter (ACh) can be released from an interneuron onto two or more follower neurons and can excite one and inhibit another or evoke a biphasic response on a third type of cell. The biphasic response of the molluscan neurons to neurotransmitters was the first demonstration of the plastic synaptic changes. The discovery of individual neurons with their groups of follower cells acting as chemical units has provided an insight into the organization of various behavioral acts. Study of the gastropod molluscs has also shown that the giant serotonergic cells can act as peripheral modulator neurons, as well as interneurons, and in this way they can affect their target organs at more than one level. The molluscan studies have provided more information on transmitter receptors as it was shown that molluscan neurons have at least six different 5HT receptors, three Ach receptors which can be separated pharmacologically. This type of study has led to the discovery of numerous new antagonists and poisons.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗