THE SELECTIVE ELIMINATION OF INTRACORTICALLY PROJECTING NEURONS OF THE RAT NEOCORTEX BY PRENATAL X-IRRADIATION
Abstract
The development of new tracing methods has suggested that there are species differences in the extent of the contribution of the different layers of the neocortex to the callosal projection. The present investigation has utilized prenatal x-irradiation to selectively eliminate the late forming neurons of the supragranular layers of the rat neocortex. The reduction in the neuronal population of the supragranular layers closely parallels the reduction in the corpus callosum. Furthermore, the callosal projection of sample block of cortex could be eliminated without a reduction in the number of neurons in the corresponding infragranular layers. These results indicate that the primary, if not sole source of neurons of the callosal projection, are the late forming neurons of the supragranular layers. Increases in neuronal density in the supra- and infragranular layers were interpreted as reflecting the extensive loss of intracortically projecting neurons. Thus, the current results suggest that low dose prenatal x-irradiation may be used to evaluate important developmental events in the formation of neocortical circuitry.
Degree
Ph.D.
Subject Area
Anatomy & physiology
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