Relation of Posttetanic Potentiation to Subnormality of Lateral Geniculate Potentials

1957 ◽  
Vol 188 (2) ◽  
pp. 238-244 ◽  
Author(s):  
Edward V. Evarts ◽  
John R. Hughes
Keyword(s):  
Electrical Stimulation ◽  
Optic Nerve ◽  
Posttetanic Potentiation ◽  
Postsynaptic Response ◽  
Lateral Geniculate ◽  
Decerebrate Cats ◽  
Stimulation Of

The lateral geniculate response to electrical stimulation of the optic nerve was recorded in decerebrate cats and in cats anesthetized with Nembutal. Tetanization of the optic nerve at 500/sec. for 20 seconds in nembutalized cats produced a prolonged second subnormality of the geniculate postsynaptic response. Further tetanization during tetanically-induced second subnormality produced posttetanic potentiation (PTP). The degree of PTP (expressed in percentage of the pretetanic level) of the postsynaptic response following a 20-second tetanus was proportional to the degree of second subnormality present at the time the tetanus was applied. PTP was also found to occur during the subnormality which followed a brief train of optic nerve shocks, and during LSD-induced subnormality. PTP of postsynaptic lateral geniculate potentials occurred only rarely in the absence of some form of intentionally induced subnormality.

Repetitive stimulation of optic nerve and lateral geniculate synapses

1959 ◽  
Vol 1 (6) ◽  
pp. 534-555 ◽  
Author(s):  
P.O. Bishop ◽  
W. Burke ◽  
W.R. Hayhow
Keyword(s):  
Optic Nerve ◽  
Repetitive Stimulation ◽  
Lateral Geniculate ◽  
Stimulation Of

Central command, but not muscle reflex, stimulates cutaneous sympathetic efferents of cats

1998 ◽  
Vol 274 (5) ◽  
pp. H1552-H1559 ◽  
Author(s):  
Janeen M. Hill ◽  
Marc P. Kaufman
Keyword(s):  
Electrical Stimulation ◽  
Blocking Agent ◽  
Muscle Afferents ◽  
Group Iii ◽  
Hairy Skin ◽  
Sympathetic Efferents ◽  
Muscle Reflex ◽  
Decerebrate Cats ◽  
Sympathetic Discharge ◽  
Stimulation Of

We determined the effects of stimulation of the mesencephalic locomotor region (MLR) and the muscle reflex, each evoked separately, on the discharge of cutaneous sympathetic fibers innervating the hairy skin of decerebrate cats. Electrical stimulation of the MLR was performed while the cats were paralyzed with vecuronium bromide. The muscle reflex was evoked while the cats were not paralyzed by electrical stimulation of the tibial nerve at current intensities that did not activate directly group III and IV muscle afferents. MLR stimulation increased, on average, the discharge of the 23 cutaneous sympathetic fibers tested ( P < 0.05). The muscle reflex, in contrast, had no overall effect on the discharge of 21 sympathetic fibers tested ( P > 0.05). Both maneuvers markedly increased mean arterial pressure and heart rate ( P < 0.05). Prevention of the baroreceptor reflex with the α-adrenergic blocking agent phentolamine did not reveal a stimulatory effect of the muscle reflex on cutaneous sympathetic discharge. We conclude that the MLR is a more important mechanism than is the muscle reflex in controlling sympathetic discharge to hairy skin during dynamic exercise.

Dual actions of isthmic input to tectal neurons in a reptile, Gekko gekko

1999 ◽  
Vol 16 (5) ◽  
pp. 889-893 ◽  
Author(s):  
STEPHEN A. GEORGE ◽  
GANG-YI WU ◽  
WEN-CHANG LI ◽  
SHU-RONG WANG
Keyword(s):  
Electrical Stimulation ◽  
Optic Nerve ◽  
Optic Tectum ◽  
Nucleus Isthmi ◽  
Postsynaptic Potentials ◽  
Tectal Neurons ◽  
Electrical Connections ◽  
Stimulation Of

We analyzed postsynaptic potentials and dye-labeled morphology of tectal neurons responding to electrical stimulation of the optic nerve and of the nucleus isthmi in a reptile, Gekko gekko, in order to compare with previously reported interactions between the optic tectum and the nucleus isthmi in amphibians and birds. The results indicate that isthmic stimulation exerts inhibitory and excitatory actions on tectal cells, similar to dual isthmotectal actions in amphibians. It appears that dual actions of the isthmotectal pathway in amphibians and reptiles are shared by two subdivisions of the nucleus isthmi in birds. The morphology of tectal cells responding to isthmic stimulation is generally similar to that of tectoisthmic projecting neurons, but they differ particularly in that some tectoisthmic cells bear numerous varicosities whereas cells receiving isthmic afferents do not. Thus, it is likely that at least some tectoisthmic cells may not be in the population of tectal cells that can be affected by isthmic stimulation. Forty-four percent of injections resulted in dye-coupled labeling, suggesting extensive electrical connections between tectal cells in reptiles.

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