Monosynaptic transmission between mesodiencephalic neurons and motoneurons innervating extraocular inferior oblique muscle in cats

The present study was performed to define the synaptic connection of neurons located within the dorsal mesodiencephalic junction with motoneurons innervating extraocular inferior oblique muscle(IOMN)using electrophysiologic,especially spike-triggered averaging technique in cats.In response to electric shocks applied to the medial part of Forel's field H(FFH) located in the mesodiencephalic junction,excitatory monosynaptic field potentials were observed in the IOMN pool.Moreover,while the spontaneous discharges of FFH neurons were used to trigger the activity of IOMN pool from which the induced potential changes were averaged,an excitatory monosynaptic field potential was also obtained.These results indicate that the mesodiencephalic neurons connect with and activate the IOMNs monosynaptically,and drive venical eye movements via such a way.