Importance of NMDA receptors for multimodal integration in the deep layers of the cat superior colliculus

Binns, K. E.; Salt, Te

doi:10.1152/jn.1996.75.2.920

Cited by 48 publications

(49 citation statements)

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“…A large body of work has shown that the NMDA receptor plays a role in the maintenance of working memory (Krystal et al, 1994;Lisman et al, 1998) and multisensory integration (Binns and Salt, 1996) as well as in long-term synaptic plasticity that may substantiate long-term memory (Collingridge et al, 1983;Kerchner and Nicoll, 2008). This study provides evidence that NMDA re- Figure 4.…”

Section: Discussionmentioning

confidence: 59%

Beneficial Effects of the NMDA Antagonist Ketamine on Decision Processes in Visual Search

Shen¹,

Kalwarowsky²,

Clarence³

et al. 2010

Journal of Neuroscience

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The ability of sensory-motor circuits to integrate sensory evidence over time is thought to underlie the process of decision-making in perceptual discrimination. Recent work has suggested that the NMDA receptor contributes to mediating neural activity integration. To test this hypothesis, we trained three female rhesus monkeys (Macaca mulatta) to perform a visual search task, in which they had to make a saccadic eye movement to the location of a target stimulus presented among distracter stimuli of lower luminance. We manipulated NMDA-receptor function by administering an intramuscular injection of the noncompetitive NMDA antagonist ketamine and assessed visual search performance before and after manipulation. Ketamine was found to lengthen response latency in a dose-dependent fashion. Surprisingly, it was also observed that response accuracy was significantly improved when lower doses were administered. These findings suggest that NMDA receptors play a crucial role in the process of decision-making in perceptual discrimination. They also further support the idea that multiple neural representations compete with one another through mutual inhibition, which may explain the speedaccuracy trade-off rule that shapes discrimination behavior: lengthening integration time helps resolve small differences between choice alternatives, thereby improving accuracy.

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Section: Discussionmentioning

confidence: 59%

Beneficial Effects of the NMDA Antagonist Ketamine on Decision Processes in Visual Search

Shen¹,

Kalwarowsky²,

Clarence³

et al. 2010

Journal of Neuroscience

View full text Add to dashboard Cite

show abstract

“…It was proposed that N-methyl-D-aspartate receptors presented in multisensory neurons in cats provide a molecular mechanism for multiplication (Binns 1999;Binns and Salt 1996). But, Patton and Anastasio (2003) argued that the experimental results of Binns and Salt (1996) as well as previous results by Meredith and Stein (1986) can be reproduced in a model using simple neural mechanisms such as synaptic summation and threshold, not requiring a specialized synaptic multiplication mechanism. A simple threshold mechanism may explain the results of the present study as well: in the bimodal stimuli, the late visual inputs arrive on top of a raised membrane potential and are therefore likely to reach threshold earlier.…”

Section: Mechanisms Of Integrationmentioning

confidence: 99%

Multisensory Enhancement in the Optic Tectum of the Barn Owl: Spike Count and Spike Timing

Zahar¹,

Reches²,

Gutfreund³

2009

Journal of Neurophysiology

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Zahar Y, Reches A, Gutfreund Y. Multisensory enhancement in the optic tectum of the barn owl: spike count and spike timing. J Neurophysiol 101: 2380 -2394, 2009. First published March 4, 2009 doi:10.1152/jn.91193.2008. Temporal and spatial correlations between auditory and visual stimuli facilitate the perception of unitary events and improve behavioral responses. However, it is not clear how combined visual and auditory information is processed in single neurons. Here we studied responses of multisensory neurons in the barn owl's optic tectum (the avian homologue of the superior colliculus) to visual, auditory, and bimodal stimuli. We specifically focused on responses to sequences of repeated stimuli. We first report that bimodal stimulation tends to elicit more spikes than in the responses to its unimodal components (a phenomenon known as multisensory enhancement). However, this tendency was found to be historydependent; multisensory enhancement was mostly apparent in the first stimulus of the sequence and to a much lesser extent in the subsequent stimuli. Next, a vector-strength analysis was applied to quantify the phase locking of the responses to the stimuli. We report that in a substantial number of multisensory neurons responses to sequences of bimodal stimuli elicited spike trains that were better phase locked to the stimulus than spike trains elicited by stimulating with the unimodal counterparts (visual or auditory). We conclude that multisensory enhancement can be manifested in better phase locking to the stimulus as well as in more spikes.

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“…In the anesthetized cat, unimodal stimuli presented within a bimodal cell's receptive field evoke weak and inconsistent responses, but spatially and temporally coincident bimodal stimuli evoke largely enhanced and consistent responses (1,000% larger than the larger single modality response; Meredith and Stein, 1986). Because stimuli with coincident temporal and spatial characteristics are likely to arise from the same event, response enhancement is thought to be a mechanism for increasing the likelihood of a behavioral response (Stein et al, 1989;Binns and Salt, 1996).…”

Section: Functional Implicationsmentioning

confidence: 99%

Cortical somatosensory and trigeminal inputs to the cat superior colliculus: Light and electron microscopic analyses

1997

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Two different axonal transport tracers were used in single animals to test the hypothesis that the expansive intermediate gray layer of the cat superior colliculus (stratum griseum intermediale, SGI) is composed of sensorimotor domains. The results show that two sensory pathways, the trigeminotectal and the corticotectal arising from the fourth somatosensory area, commingle in patches across the middle tier of the SGI. Furthermore, the data reveal that tectospinal cells are distributed within these patches. Taken together, these results show a commingling of functionally related afferents and a consistent spatial relationship between these afferents and tectospinal neurons. These relationships indicate that the SGI consists of domains that can be distinguished by their unique combinations of afferent and efferent connections. The ultrastructural characteristics and synaptic relationships of these somatosensory afferent pathways suggest that they have distinct roles within the sensorimotor domain of the SGI. The trigeminotectal terminals are relatively small, contain round vesicles and make asymmetrical synapses on small, presumably distal, dendrites. We submit that these trigeminal terminals bestow the basic receptive field properties upon SGI neurons. In contrast, the somatosensory corticotectal terminals are relatively large, contain round vesicles, make asymmetrical synapses, participate in triads, and are presynaptic to proximal dendrites. We suggest that these cortical terminals bestow integrative abilities on SGI neurons.

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Importance of NMDA receptors for multimodal integration in the deep layers of the cat superior colliculus

Cited by 48 publications

References 0 publications

Beneficial Effects of the NMDA Antagonist Ketamine on Decision Processes in Visual Search

Beneficial Effects of the NMDA Antagonist Ketamine on Decision Processes in Visual Search

Multisensory Enhancement in the Optic Tectum of the Barn Owl: Spike Count and Spike Timing

Cortical somatosensory and trigeminal inputs to the cat superior colliculus: Light and electron microscopic analyses

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