A type of basket cell in superficial layers of the cat visual cortex. A Golgi-electron microscope study.

The axonal arborizations of the basket cells in the cerebral neocortex have long been considered as the source of the presynaptic terminals contacting the cell bodies of pyramidal cells. Given that the concept of the cortical basket cell is based upon indirect evidence only, it was deemed worthwhile to re-investigate this problem using the Golgi-EM technique. This approach permits one to trace the presynaptic terminals back to their parent cell body, so that it allows for a positive identification of basket cells, i.e. cells which produce axosomatic synapses by preference. A type of interneuron in layer II-III of the cat visual cortex is described. Its axon treminals form multiple synaptic contacts, of the symmetrical type, on cell bodies and proximal dendrites of pyramidal and non-pyramidal cells. On the basis of this efferent synaptic pattern, this interneuron is considered to be a basket cell. The possible correspondence of this interneuronal type with other putative basket cells described in previous Golgi studies is discussed. In addition, a simple re-section method for semithin sections is described, which has been used to identify individual Golgi-impregnated axonal boutons in electron microscopy.