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Christian Casanova, Marilyse Piché, Brian Ouellette; Spatiotemporal properties of LP-pulvinar visual receptive fields. Journal of Vision 2008;8(6):809. doi: 10.1167/8.6.809.
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© ARVO (1962-2015); The Authors (2016-present)
The lateral posterior-pulvinar complex (LP-pulvinar) of the cat is divided into the lateral (LPl), the medial (LPm) and the pulvinar nuclei. Each sub-nucleus entertains reciprocal connections with, among other areas, area 17 and PMLS cortex. While the RF properties of neurons in the LPm and LPl have been previously described, the techniques did not allow an in depth study of the temporal dimension. This is unfortunate as it is unclear how, if at all, the LP-pulvinar modifies information along cortico-thalamo-cortical loops. The goal of this study was to characterize spatiotemporal properties of the RF of LP-pulvinar neurons using the 2D reverse correlation technique. We recorded single unit activity in the LPm, LPl and pulvinar of anaesthetized cats. No clear distinction in RF characteristics between neurons in the LPm or LPl was observed. We found that 25% of the cells were exclusively dark-excitatory (DE), more than 50% of the cells were bright-excitatory (BE) and DE, and only 9 cells were activated by gratings but did not responded significantly to this test. The latencies of the peak responses were distributed between 45ms to 155 ms. Only 44% of neurons had a synchronous response to both stimuli, while 18% of the cells showed a “bi-lobe” temporal response, as it was previously found in PMLS. Of the BE/DE cells, 72% were complex-like as both subregions were superimposed spatially. Clear inhibitory subregions were observable in time or space in only five cells. Overlapping spatiotemporal RFs are consistent with known area 17 projections to the LPl. However, a high proportion (81%) displays response dynamics that cannot easily be explained by cortico-thalamic projections. This suggests that LP-pulvinar cells receive multiple visual inputs, at different time delays, allowing diversity in RF dynamics. Supp: CIHR to CC.
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