Visual features evoke reliable bursts in the perigeniculate sector of the thalamic reticular nucleus
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1
University of Southern California, United States
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2
University of California, United States
Relay cells in the cat’s lateral geniculate nucleus of the thalamus receive feedback inhibition from the perigeniculate sector of the reticular formation. Both relay cells and reticular neurons fire tonic spikes in addition to stereotyped bursts that must be primed by prolonged hyperpolarization. Bursts fired by relay cells have been studied intensively. Typically, they are primed by stimuli of the non-preferred polarity that occupy the receptive field for long times and are triggered just as luminance contrast returns to the preferred sign [1-4]. For example, in the case of On center relay cells, bursts signal the recent removal of a persistent dark stimulus, and vice versa for OFF center cells. We wondered what, if any, visual features might drive reticular cells to burst. Since most cells in the perigeniculate are excited by stimuli of both contrasts, it seemed unlikely that the simple, alternating bright/dark patterns that evoke bursts from relay cells would be effective. To explore this issue we made extracellular recordings from reticular cells while displaying natural scene movies. The movies elicited patterns of tonic spikes interspersed with periods of inactivity followed by bursts. To estimate the features, or spatiotemporal receptive fields (STRFs), that preceded tonic or burst spikes, we used publicly available software (STRFPak http://strfpak.berkeley.edu). The STRFs constructed from tonic spikes peaked shortly before the neural response, whereas the STRFs constructed from burst spikes peaked farther back in time. This is consistent with work in the lateral geniculate that suggests that stimulus sequences associated with bursts prime rather than directly elicit firing [1-4]. It was surprising to find, however, that the spatial peaks of the tonic and burst STRFs were sometimes displaced rather than overlapping. Hence, the features that evoke tonic spikes can be different from those that prime bursts. These results led us to ask if certain types of stimuli evoke bursts more reliably than others and if visually driven bursts in the perigeniculate are produced as reliably as those in the lateral geniculate [1, 2]. To address these questions, we used the Fano factor to compare trial by trial variability in bursts evoked by natural movies versus Gaussian white noise. For both reticular and relay cells, movies evoked bursts with high, subpoisson, fidelity (Fano factor < 1) whereas the Fano factor for bursts evoked by noise was typically supra-poisson (Fano factor > 1). Collectively, our results suggest that reticular bursts reliably encode specific sensory features. Thus, intrinsic thalamic circuits are capable of sophisticated visual processing.
References
1. Alitto, H.J., T.G. Weyand, and W.M. Usrey. J. Neurosci, 2005. 25: p. 514.
2. Denning, K.S. and P. Reinagel, J. Neurosci, 2005. 25: p. 3531.
3. Lesica, N.A. and G.B. Stanley, J. Neurosci 2004. 24: p. 10731.
4. Wang, X., et al., Neuron, 2007. 55: p. 465.
Conference:
Computational and Systems Neuroscience 2010, Salt Lake City, UT, United States, 25 Feb - 2 Mar, 2010.
Presentation Type:
Poster Presentation
Topic:
Poster session II
Citation:
Vaingankar
V,
Sanchez
CS,
Wang
X,
Bains
A,
Sommer
FT and
Hirsch
J
(2010). Visual features evoke reliable bursts in the perigeniculate sector of the thalamic reticular nucleus.
Front. Neurosci.
Conference Abstract:
Computational and Systems Neuroscience 2010.
doi: 10.3389/conf.fnins.2010.03.00321
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Received:
08 Mar 2010;
Published Online:
08 Mar 2010.
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Correspondence:
Vishal Vaingankar, University of Southern California, Los Angeles, United States, vaingank@usc.edu