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. 2003 Jun 15;23(12):5264-71.
doi: 10.1523/JNEUROSCI.23-12-05264.2003.

State-dependent processing of sensory stimuli by thalamic reticular neurons

Jed A Hartings  1 , Simona Temereanca, Daniel J Simons
Affiliations

State-dependent processing of sensory stimuli by thalamic reticular neurons

Jed A Hartings et al. J Neurosci. .

Abstract

Inhibitory neurons of the thalamic reticular (RT) nucleus fire in two activity modes, burst and tonic, depending on an animal's behavioral state. In tonic mode, depolarized RT cells fire single action potentials continuously, whereas burst firing consists of grouped discharges separated by periods of quiescence. To determine how these firing modes affect sensory-evoked RT responses, single-unit responses to controlled whisker deflections were analyzed according to the burst versus tonic mode of spontaneous activity (SA) preceding the response. After burst mode activity (i.e., either quiescence or spontaneous bursts), responses exhibited a slow approximately 15 msec rise to peak firing rates followed by a approximately 35 msec decay. Interspike intervals within the response exhibited accelerando-decelerando patterns similar to those of spontaneous bursts. After tonic mode activity (i.e., single spikes), responses had a nearly instantaneous approximately 1.5 msec rise-to-peak followed by a approximately 40 msec decay, with large spike counts (5.2 spikes per stimulus) similar to those evoked in burst mode (6.2 spikes per stimulus). Interspike intervals were longer in tonic mode and exhibited a decelerando pattern. Initial evoked spikes, however, had shorter latencies and greater synchrony, contributing to the rapid onset of tonic population response. Shifts from quiescent (presumed burst mode) to tonic SA could be induced by either previous whisker deflections or iontophoretic application of NMDA; both manipulations effected appropriate shifts from burst to tonic response spike patterns. In awake animals, burst and tonic firing in RT, as in thalamocortical relay nuclei, may reflect sensory processing strategies appropriate for different behavioral and attentional states.

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Figures

Figure 1.
Figure 1.
Heterogeneity of spontaneous and stimulus-evoked spike patterns in RT. A–F, Raster plots of single-unit responses; each panel shows a separate unit. For each unit 10 trials × four directions spanning 135° in 45° increments are shown; trials at each of the four directions are separated by tick marks. The total duration is 500 msec, and the stimulus waveform is shown below.
Figure 3.
Figure 3.
ISI patterns of evoked responses. A, B, Distributions of ISI values for consecutive ISIs numbers (1–6) occurring after stimulus onset. A and B were accumulated separately for responses after quiescent (Fig. 2 A) and single spike (Fig. 2 B) SA, respectively. The ordinate axes represent frequency (number of ISIs/100 μsec bin/number of trials) and are shown on different scales. The abscissa in A has an expanded scale to show differences between its distribution curves. C, Mean ISI values (±SEM) after quiescent (▪) and single spike (○) SA. For each ISI number, values were significantly different between the two conditions (p < 0.001). ISIs accumulated for all spontaneously occurring bursts (▴) are shown for comparison. D, First spike latencies are plotted versus fourth ISI values for all quiescent (black) and single spike (red) SA trials.
Figure 2.
Figure 2.
State-dependent population responses. Evoked response PSTHs were accumulated by separation of responses on a trial-by-trial basis according to classification of SA occurring 150 msec before the stimulus. A,No SA. B, Grouped discharge. C, Two or more single spikes. D, One spike.
Figure 4.
Figure 4.
State-dependent single-unit responses. A, C, E, The first 10 consecutive ISI values after stimulus onset for trials with no SA (A), grouped discharge SA (C), and more than or equal to five single spikes (E). Each graph shows seven trials from a separate unit. B,D,F, The same data as in A,C, and E, respectively, plotted in raster format. G, PSTHs were accumulated on the basis of the timing of the first spike only for all trials with no SA (gray) and all trials with single spike SA (black). H, Raster plots of ON and OFF responses of a unit to 10 whisker deflection trials at the same deflection angle. The dotted line is placed to facilitate comparison of OFF response latencies when preceded by tonic versus no activity. No activity preceded the ON response on any trial.
Figure 5.
Figure 5.
Mean effects of APV on RT activity. A, PSTHs accumulated over 22 units and all deflection angles, under control conditions (open histogram) and during APV application (filled histogram). B, PSTHs for all 22 units at directions evoking their maximal ON responses.
Figure 6.
Figure 6.
Effects of NMDA on single-unit responses. A, B, Responses of two single units to 40 stimulus trials under control conditions, during NMDA iontophoresis, and after recovery. Conventions are the same as in Figure 1.
Figure 7.
Figure 7.
Mean effects of NMDA on RT responses. A, PSTHs were accumulated over 12 units and all deflection angles, under control conditions and during NMDA microiontophoresis. Reductions in ON responses (NMDA response divided by control response) are shown as a function of the NMDA-induced increase in the recorded unit's SA (B), and the amplitude of iontophoretic current applied (C). Each symbol represents a single unit.
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References

    1. Contreras D, Dossi RC, Steriade M ( 1993) Electrophysiological properties of cat reticular thalamic neurones in vivo J Physiol (Lond) 470: 273–294. - PMC - PubMed
    1. Cox CL, Huguenard JR, Prince DA ( 1996) Heterogeneous axonal arborizations of rat thalamic reticular neurons in the ventrobasal nucleus. J Comp Neurol 366: 416–430. - PubMed
    1. Crick F ( 1984) Function of the thalamic reticular complex: the searchlight hypothesis. Proc Natl Acad Sci USA 81: 4586–4590. - PMC - PubMed
    1. Domich L, Oakson G, Steriade M ( 1986) Thalamic burst patterns in the naturally sleeping cat: a comparison between cortically projecting and reticularis neurons. J Physiol (Lond) 379: 429–449. - PMC - PubMed
    1. Dworkin BR, Dworkin S ( 1995) Learning of physiological responses: II. Classical conditioning of the baroreflex. Behav Neurosci 109: 1119–1136. - PubMed

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