Presynaptic inhibition in the vertebrate central nervous system.

The role of GABA in primary afferent depolarization.

Publisher Summary This chapter provides a preliminary account of some of the selective costs and benefits that are involved in the evolution of learning by natural selection. The term “evolution” refers to a change in the population-typical phenotype over some period of time. The aim of a cost-benefit analysis is to allow making statements about the conditions under which particular kinds of adaptations are likely to evolve and explain the reasons for these adaptations being observed in some populations and not in others. Such statements may be either qualitative or quantitative and they may account to a greater or lesser degree for the details of an adaptive trait. The chapter emphasizes on qualitative considerations. It identifies six potential selective costs of learning––namely, delayed reproductive effort and/or success, increased juvenile vulnerability, increased parental investment in each offspring, greater complexity of the central nervous system, greater complexity of the genome, and developmental fallibility.

Selective costs and benefits of in the evolution of learning

The convulsant alkaloid bicuculline blocked presynaptic inhibition, dorsal root potentials, primary afferent depolarization, and depolarizing effects of gamma-aminobutyric acid on dorsal root terminals of the amphibian spinal cord, but did not block effects of other putative amino acid transmitters. These actions of bicuculline suggest that gamma-aminobutyric acid may be the transmitter involved in spinal presynaptic inhibition.

A.K Tebēcis

Papers

The effects of topically applied biogenic monoamines on the isolated toad spinal cord.

The effects of topically applied cholinomimetic drugs on the isolated spinal cord of the toad

Reflex response changes of the toad spinal cord to variations in temperature and pH.