Electrophysiological projections of pulvinar-lateralis posterior complex (P-LP) upon superior colliculus units in the cat.
The effect of Pulvinar-Lateral Posterior (P-LP) electrical stimulation on superior colliculus unitary responses and eye movements is analyzed in 17 encéphale isolé cats. Twelve of them were curarized. Out of a total of 190 recorded units, 117 were localized in the superior colliculus and 73 units in the Mesencephalic Reticular Formation (MRF) below the superior colliculus. Thirty eight per cent (n = 45) of the collicular units modified their discharge frequency when the ipsilateral P-LP was electrically stimulated. The current intensity thresholds of transynaptic activation had a range between 0.5 and 2.0 mA. Most of the orthodromic responses were produced by ipsilateral P-LP stimulation and were localized in the intermediate and deep layers of the superior colliculus. Three types of responses were obtained: short latency responses between 2 and 10 ms (57%); intermediate latency responses between 15 and 40 ms (29%), and long latency responses between 50 and 200 ms (14%). Thirty one per cent (n = 18) of the units recorded in the MRF responded to P-LP stimulation with 10 ms pulse-trains duration. In the MRF 3 types of responses were observed: 1) a decrease or blockade in the resting discharge during 20 to 100 ms after stimulation (20%); simple responses with a latency between 25 and 150 ms (40%), and complex responses with an early response and a latency between 15-40 ms, and a late response with a latency between 150 and 200 ms (40%).(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D001931:Brain Mapping; D002415:Cats; D004525:Efferent Pathways / Q000502:physiology; D005071:Evoked Potentials; D005133:Eye Movements; D005260:Female; D008297:Male; D008636:Mesencephalon / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012154:Reticular Formation / Q000502:physiology; D013477:Superior Colliculi / Q000502:physiology*; D013569:Synapses / Q000502:physiology; D013787:Thalamic Nuclei / Q000502:physiology*