Role of inhibition in shaping reliability: trial-by-trial variability of visual responses in superior colliculus is influenced by GABA

• Autorzy: Wypych M. , Mochol G. , Foik A. , Waleszczyk W.J.
• Języki publikacji: EN

Abstrakty

EN

Previously we have shown that variability of visual responses of superior colliculus (SC) neurons depended on whether the main visual input to the cell was of Y- or W-channel origin (Mochol et al. 2010). To better understand the mechanisms underlying previous finding in this study we test whether GABAergic system influences the variability of SC visual responses. In acute experiments on anesthetized cats extracellular responses of single neurons to spot of light moving in broad range of velocities were recorded from retinorecipient, superficial layers of SC, allowing to determine the Y- or W-channel input. Simultaneously local iontophoretic injections of GABA (nonspecific GABA receptors agonist) or bicuculline (GABAA receptors antagonist) were performed. Trial-by-trial variability was assessed with Fano factor (FF; ratio of variance of spike counts to mean number of spikes in a given period of time). In the majority of cells application of GABA resulted in decrease of firing rate (FR) and changes of FF. These changes were consistent with previously found correlations between FR and FF. If major input to the tested neuron was of Y-channel origin and changes in FF correlated negatively with changes in FR, GABA-induced decrease of FR was accompanied by an increase of FF. In the case of major W-type input the result was opposite: FF followed changes in FR, consistent with positive correlation between the two in control trials. Injection of bicuculline however, which typically resulted in an increase of neural activity, did not lead to coherent changes of variability. The FF could change slightly or remain unchanged independently of the correlation of FF and FR in control trials. Our results show that GABAergic system may play different roles in shaping the reliability of visual responses in SC depending on the origin of visual input and types of GABA receptors involved. Supported by Polish MSHE grant N N303 070234.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2011
• Tom: 71
• Numer: S
• Opis fizyczny: p.86

Twórcy

autor

Wypych M.

• Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland

autor

Mochol G.

• Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland

autor

Foik A.

• Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland

autor

Waleszczyk W.J.

• Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland

Uwagi

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