Neuroanatomical studies of the nigrotectal projection in the cat

Harting, John K.; Huerta, Michael F.; Hashikawa, Tsutomu; Weber, Joseph T.; Lieshout, David P. Van

doi:10.1002/cne.902780412

Cited by 113 publications

(66 citation statements)

References 66 publications

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“…This region provides input to the upper half of the intermediate layers of the SC, which is also presumably the location of the saccaderelated burst neurons (Harting et al 1988;Huerta et al 1991;May and Hall 1984;Munoz and Wurtz 1995). There is some suggestion that the buildup neurons are located below the burst neurons, in the lower part of the intermediate layers (Munoz and Wurtz 1995;Rodgers et al 2006;Wurtz and Munoz 1994).…”

Section: Relationship To Previous Work On the Uncrossed Snr-sc Pathwaymentioning

confidence: 99%

Substantia Nigra Stimulation Influences Monkey Superior Colliculus Neuronal Activity Bilaterally

Liu¹,

Basso²

2008

Journal of Neurophysiology

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Liu P, Basso MA. Substantia nigra stimulation influences monkey superior colliculus neuronal activity bilaterally. J Neurophysiol 100: 1098 -1112, 2008. First published June 25, 2008 doi:10.1152/jn.01043.2007. The inhibitory drive arising from the basal ganglia is thought to prevent the occurrence of orienting movements of the eyes, head, and body in monkeys and other mammals. The direct projection from the substantia nigra pars reticulata (SNr) to the superior colliculus (SC) mediates the inhibition. Since the original experiments in the SNr of monkeys the buildup or prelude neuron has been a focus of SC research. However, whether the SNr influences buildup neurons in SC is unknown. Furthermore, a contralateral SNr-SC pathway is evident in many species but remains unexplored in the alert monkey. Here we introduced electrical stimulation of one or both SNr nuclei while recording from SC buildup neurons. Stimulation of the SNr reduced the discharge rate of SC buildup neurons bilaterally. This result is consistent with activation of an inhibitory drive from SNr to SC. The time course of the influence of ipsilateral SNr on the activity of most SC neurons was longer (ϳ73 ms) than the influence of the contralateral SNr (ϳ34 ms). We also found that the variability of saccade onset time and saccade direction was altered with electrical stimulation of the SNr. Taken together our results show that electrical stimulation activates the inhibitory output of the SNr that in turn, reduces the activity of SC buildup neurons in both hemispheres. However, rather than acting as a gate for saccade initiation, the results suggest that the influence of SNr inhibition on visually guided saccades is more subtle, shaping the balance of excitation and inhibition across the SC.

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Section: Relationship To Previous Work On the Uncrossed Snr-sc Pathwaymentioning

confidence: 99%

Substantia Nigra Stimulation Influences Monkey Superior Colliculus Neuronal Activity Bilaterally

Liu¹,

Basso²

2008

Journal of Neurophysiology

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“…For example, substantia nigra pars reticulata is the source of a widespread GABAergic pathway that tonically inhibits both ipsilateral and contralateral SGI cells. (Chevalier et al, 1981;Hikosaka and Wurtz, 1983;May and Hall, 1984;Karabelas and Moschovakis, 1985;Harting et al, 1988;Bickford and Hall, 1992;Basso and Wurtz, 2002). A winner-take-all mechanism could be mediated by local disinhibition of the premotor cells produced by a spatially selective decrease in nigral cell activity, in combination with a build up in the activity of the premotor cells by afferent pathways and recurrent excitation (Das et al, 1996).…”

Section: Evidence For Widespread Inhibition and Excitation Within Sgimentioning

confidence: 99%

AnIn VitroStudy of Horizontal Connections in the Intermediate Layer of the Superior Colliculus

Lee

Hall²

2006

J. Neurosci.

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Some models propose that the spatial and temporal distributions of premotor activity in the intermediate layer of the superior colliculus are shaped by neuronal ensembles that give rise to local excitatory and distant inhibitory connections. One function proposed for these connections is to mediate a "winner-take-all" network; the short-range excitatory connections build up the activity of neighboring cells that command orienting movements in one direction, whereas the wide-ranging inhibitory projections attenuate the activity of remote cells that command incompatible movements. We used in vitro photostimulation and whole-cell patch-clamp recording to test these models by measuring the spatial extent of synaptic interactions within the rat intermediate layer.

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“…It is well documented that the motor output of the SC is shaped by a strictly held balance between excitation and inhibition. Local injections of bicuculline (a GABA antagonist), muscimol (a GABA agonist), or muscimol into the substantia nigra pars reticulata, an inhibitory input to the SC (Graybiel, 1978;Harting et al, 1988), affect the animal's oculomotor behavior (Boussaoud and Joseph, 1985;Hikosaka and Wurtz, 1985a,b). Thus, questions arise as to whether the processing of sensory inputs in the SC is also under the control of the hypothesized excitation/inhibition balance and whether facilitation can result from altering such balance with anesthetics.…”

Section: Introductionmentioning

confidence: 99%

Anesthetics Change the Excitation/Inhibition Balance That Governs Sensory Processing in the Cat Superior Colliculus

Populin

2005

J. Neurosci.

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The superior colliculus (SC) is a midbrain structure that plays a central role in the integration of information from different sensory modalities and the generation of orienting responses. Its normal function is thought to be governed by a strictly held balance between excitation and inhibition. This hypothesis was tested by recording from the same single units in the SC of cats before the injection of anesthetics, while anesthetics took effect, and after the injections during recovery. Sodium pentobarbital and ketamine, two agents commonly used in sensory physiology, were used. The results show a plethora of dose-dependent and nonlinear effects: the magnitude of evoked responses, receptive field properties, first spike latency, and bimodal integration were affected by both anesthetics in all units tested. Notably, prominent facilitation was observed at low levels of anesthesia, and inhibitory responses were changed into excitatory. Overall, the results challenge a fundamental tenet of sensory physiology: anesthesia, while decreasing single-unit responsiveness, leaves unaltered basic physiological properties.

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Neuroanatomical studies of the nigrotectal projection in the cat

Cited by 113 publications

References 66 publications

Substantia Nigra Stimulation Influences Monkey Superior Colliculus Neuronal Activity Bilaterally

Substantia Nigra Stimulation Influences Monkey Superior Colliculus Neuronal Activity Bilaterally

AnIn VitroStudy of Horizontal Connections in the Intermediate Layer of the Superior Colliculus

Anesthetics Change the Excitation/Inhibition Balance That Governs Sensory Processing in the Cat Superior Colliculus

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