Plasticity and the Mystacial Vibrissae of Rodents

Abstract

The neural pathway linking the mystacial vibrissae of rats and mice with the face region of the contralateral SI cerebral cortex has been used more extensively for studying the plasticity of neural connections than any other part of the somatosensory system. To the experimenter this system offers three unique advantages. Firstly, each vibrissa is easily detectable in prenatal, neonatal and adult animals (Vincent 1913; Zucker and Welker 1969; Woolsey and Van der Loos 1970; Van der Loos and Woolsey 1973; Van der Loos and Dorfl 1978; Yamakado and Yohro 1979; Andres and Van der Loos 1983,1985). Secondly, in animals older than one week, the spatial arrangement of the vibrissae is replicated in histochemical and/or cytoarchitectonic features at the levels of the TNC, the VB complex and the cortex (Woolsey and Van der Loos 1970; Killackey et al. 1976; Van der Loos 1976; Belford and Killackey 1979; Killackey and Belford 1979; Ma and Woolsey 1984; Bates and Killackey 1985). Thirdly, these neuroanatomical correlates of the vibrissae are not apparent at birth but develop over the first week of postnatal life (Rice and Van der Loos 1977; Killackey and Belford 1979; Belford and Killackey 1979). These features underscore the importance of the vibrissa system in answering questions that relate to the plasticity of neural circuitry during its establishment. It is generally conceded that such questions are intimately bound to understanding the factors controlling the normal development of the brain rather than those mechanisms which confer upon the mature nervous system the property of plasticity.