Afferent connections of the neurons in the Forel's field of H in cat.

An anatomico-physiological analysis was made to elucidate afferent connections of the neurons in the Forel's field of H (FFH) by horseradish peroxidase retrograde tracing technique and by evoked potential technique. 1) The FFH neurons receive fibers from the neocortex (layer V) and brainstem reticular formations. 2) Physiological projections from the mesencephalic reticular formation to the FFH as well as to the motor cortex were ipsilateral, but those from the pons and medulla oblongata were bilateral. 3) These data will suggest that the FFH neurons are in junction of the cortico-reticular connections and play an important role in the maintenance of an epileptic excitability of the neocortical system as suggested by Jinnai and Mukawa.