All visual signals the cortex receives are influenced by the perigeniculate sector (PGN) of the thalamic reticular nucleus, which receives input from relay cells in the lateral geniculate and provides feedback inhibition in return. Relay cells have been studied in quantitative depth; they behave in a roughly linear fashion and have receptive fields with a stereotyped center-surround structure. We know far less about reticular neurons. Qualitative studies indicate they simply pool ascending input to generate non-selective gain control. Yet the perigeniculate is complicated; local cells are densely interconnected and fire lengthy bursts. Thus, we employed quantitative methods to explore the perigeniculate using relay cells as controls. By adapting methods of spike-triggered averaging and covariance analysis for bursts, we identified both first and second order features that build reticular receptive fields. The shapes of these spatiotemporal subunits varied widely; no stereotyped pattern emerged. Companion experiments showed that the shape of the first but not second order features could be explained by the overlap of On and Off inputs to a given cell. Moreover, we assessed the predictive power of the receptive field and how much information each component subunit conveyed. Linear-non-linear (LN) models including multiple subunits performed better than those made with just one; further each subunit encoded different visual information. Model performance for reticular cells was always lesser than for relay cells, however, indicating that reticular cells process inputs non-linearly. All told, our results suggest that the perigeniculate encodes diverse visual features to selectively modulate activity transmitted downstream.
Keywords: LGN, TRN, inhibition, receptive field, thalamus
Citation: Vaingankar V, Soto-Sanchez C, Wang X, Sommer FT and Hirsch JA (2012) Neurons in the thalamic reticular nucleus are selective for diverse and complex visual features. Front. Integr. Neurosci. 6:118. doi: 10.3389/fnint.2012.00118
Received: 09 November 2012; Paper pending published: 22 November 2012;
Accepted: 29 November 2012; Published online: 24 December 2012.
Edited by:Martin W. Usrey, University of California, Davis, USA
Reviewed by:Jose-Manuel Alonso, State University of New York, USA
Copyright © 2012 Vaingankar, Soto-Sanchez, Wang, Sommer and Hirsch. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.
*Correspondence: Judith A. Hirsch, Department of Biological Sciences, University of Southern California, 328 Hedco Neurosciences Building, MC 2520, 3641 Watt Way, Los Angeles, CA 90089-2520, USA. e-mail: email@example.com