[Morphologic characteristics of the population of neurons in the cat auditory cortex, projecting into the medial geniculate body].

Neurons from the auditory cortex projecting into the medial geniculate body were studied in cats using the horseradish peroxidase. Such neurons were located in deep layers of the auditory cortex--predominantly in layer VI, and to a lesser extent in layer V. Dimensions of the pericarions of the labelled neurons were measured and types of neurons were determined. The overwhelming majority of cortico-geniculate neurons was pyramidal, and quantity of such neurons in layer VI of the first auditory cortex may reach 60% of the total number of cells in this layer. On the basis of the anterograde transport of HRP deep layer III and layer IV of the auditory cortex were determined as main targets of geniculocortical fibres.