EFFECT OF FORNICAL STIMULATION UPON THE CA1 AND CA2 APICAL DENDRITE OF RABBIT'S HIPPOCAMPUS

Abstract

A neural structure, stimulation of which evoked a postsynaptic potential in the apical dendrite of CA1 or CA2 was found within the rabbits hippocampus. The slow potential inhibited the spike of the apical dendrite. It was found that the fornix contained at least two pathways to the hippocampus, one exciting and the other inhibiting the activity of the apical dendrite. The former was considered as the antidromic pathway, generating spike in the apical dendrite by way of the Schaffer collaterals. The latter was regarded as the same as that found by Green et aL in 1956 But as for its function, quite contrary to Green et al. it was found that impulses running this pathway inhibited the spike of the apical dendrite by generating a slow positive potential. The inhibitory pathway was considered entering directly into the Ammon''s horn, without changing synapses at the granule cells.