Electrical Stimulation of Substantia Nigra Pars Reticulata Is Anticonvulsant in Adult and Young Male Rats

Gaze is strongly attracted to visual objects that have been associated with rewards. Key to this function is a basal ganglia circuit originating from the caudate nucleus (CD), mediated by the substantia nigra pars reticulata (SNr), and aiming at the superior colliculus (SC). Notably, subregions of CD encode values of visual objects differently: stably by CD tail [CD(T)] vs. flexibly by CD head [CD(H)]. Are the stable and flexible value signals processed separately throughout the CD-SNr-SC circuit? To answer this question, we identified SNr neurons by their inputs from CD and outputs to SC and examined their sensitivity to object values. The direct input from CD was identified by SNr neuron's inhibitory response to electrical stimulation of CD. We found that SNr neurons were separated into two groups: 1) neurons inhibited by CD(T) stimulation, located in the caudal-dorsal-lateral SNr (cdlSNr), and 2) neurons inhibited by CD(H) stimulation, located in the rostral-ventral-medial SNr (rvmSNr). Most of CD(T)-recipient SNr neurons encoded stable values, whereas CD(H)-recipient SNr neurons tended to encode flexible values. The output to SC was identified by SNr neuron's antidromic response to SC stimulation. Among the antidromically activated neurons, many encoded only stable values, while some encoded only flexible values. These results suggest that CD(T)-cdlSNr-SC circuit and CD(H)-rvmSNr-SC circuit transmit stable and flexible value signals, largely separately, to SC. The speed of signal transmission was faster through CD(T)-cdlSNr-SC circuit than through CD(H)-rvmSNr-SC circuit, which may reflect automatic and controlled gaze orienting guided by these circuits.

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Context-Dependent Effects of Substantia Nigra Stimulation on Eye Movements

Journal of Neurophysiology ◽

10.1152/jn.00094.2007 ◽

2007 ◽

Vol 97 (6) ◽

pp. 4129-4142 ◽

Cited By ~ 32

Author(s):

Michele A. Basso ◽

Ping Liu

Keyword(s):

Electrical Stimulation ◽

Visual Field ◽

Substantia Nigra ◽

Saccade Latency ◽

Substantia Nigra Pars Reticulata ◽

Visually Guided ◽

Output Structure ◽

Vector Direction ◽

Made In ◽

Stimulation Of

In a series of now classic experiments, an output structure of the basal ganglia (BG)—the substantia nigra pars reticulata (SNr)—was shown to be involved in the generation of saccades made in particular behavioral contexts, such as when memory was required for guidance. Recent electrophysiological experiments, however, call this original hypothesis into question. Here we test the hypothesis that the SNr is involved preferentially in nonvisually guided saccades using electrical stimulation. Monkeys performed visually guided and memory-guided saccades to locations throughout the visual field. On 50% of the trials, electrical stimulation of the SNr occurred. Stimulation of the SNr altered the direction, amplitude, latency, and probability of saccades. Visually guided saccades tended to be rotated toward the field contralateral to the side of stimulation, whereas memory-guided saccades tended to be rotated toward the hemifield ipsilateral to the side of stimulation. Overall, the changes in saccade vector direction were larger for memory-guided than for visually guided saccades. Both memory- and visually guided saccades were hypometric during stimulation trials, but the stimulation preferentially affected the length of memory-guided saccades. Electrical stimulation of the SNr produced decreases in visually guided saccades bilaterally. In contrast, memory-guided saccades often had increases in saccade latency bilaterally. Finally, we found approximately 10% reduction in the probability of memory-guided saccades bilaterally. Visually guided saccade probability was unaltered. Taken together the results are consistent with the hypothesis that SNr primarily influences nonvisually guided saccades. The pattern of stimulation effects suggests that SNr influence is widespread, altering the pattern of activity bilaterally across the superior colliculus map of saccades.

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OVULATORY DISCHARGE OF GONADOTROPHINS INDUCED BY HYPOTHALAMIC STIMULATION IN CASTRATED MALE RATS BEARING A TRANSPLANTED OVARY

Acta Endocrinologica ◽

10.1530/acta.0.0510281 ◽

1966 ◽

Vol 51 (2) ◽

pp. 281-289 ◽

Cited By ~ 5

Author(s):

J. Moll ◽

G. H. Zeilmaker

Keyword(s):

Electrical Stimulation ◽

Preoptic Area ◽

Hypothalamic Stimulation ◽

Male Rats ◽

Corpora Lutea ◽

Histological Changes ◽

Experimental Animals ◽

Cumulus Oophorus ◽

Dc Current ◽

Stimulation Of

ABSTRACT Castrated young adult inbred male rats bearing ovarian transplants were subjected to electrical stimulation of the hypothalamus. This was done in order to investigate whether discharge of ovulatory amounts of gonadotrophins could be induced in such male animals by this procedure. Bilateral stimulations with unipolar electrodes and a DC current of 1.5 mA applied during 10 seconds induced in the ovarian grafts histological changes indicating the discharge of ovulatory amounts of gonadotrophins. In animals killed one day after stimulation these changes consisted of displacement of the ova towards the centre of the follicles with loosening of the cumulus oophorus. In one animal the ova had left the follicles. In animals killed three days after stimulation numerous young corpora lutea could be observed. These results were obtained with electrode tips either close to the median eminence, or in the preoptic area. Shamstimulations were ineffective. Some of the experimental animals received progesterone pretreatment. This rendered the stimulations ineffective, if continued until the day preceding stimulation, but seemed without effect on the results of stimulation, if two or three days without progesterone preceded the stimulations.

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