Nucleus specific cortical control in the thalamus of the rat, convergence of cortical and peripheral driver afferents
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1
Hungarian Academy of Sciences, Institute of Experimental Medicine, Hungary
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2
Technical University, Institute of Neuroscience, Germany
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3
Laval University, CRULRG, Canada
Sensory thalamic nuclei can be categorized according to the morphology of terminals arising from cortical afferents. First order (FO) thalamic relays are innervated solely by small, layer VI cortical terminals, whereas higher order (HO) thalamic relays receive giant terminals from layer V (L5) pyramidal cells as well. In addition, all nuclei receive giant excitatory terminals from subcortical centers. Here we examined the effect of corticothalamic input in vivo in anesthetized rodents by comparing the intracellular activity of the FO somatosensory ventral posteromedial (VPM) nucleus and HO nucleus posterior (Po) and by photostimulation of channel rhodopsin 2 (ChR2) expressing L5 pyramidal cells. As Po is targeted by both cortical L5 and subcortical giant terminals, their putative convergent influence on the same Po cell was also studied.
The intracellular activity of Po, but not VPM neurons was characterized by fast rising, large amplitude EPSPs coherent with the cortical slow oscillation. Transient cortical inactivation abolished fast rising EPSPs in Po cells demonstrating their cortical origin. Stimulation of L5 by light pulses in ChR2 transgenic mice triggered short latency action potentials in Po with high fidelity, but led to rapid depression even at 5 Hz.
In Po traced L5 terminals from the S1 cortex partly overlapped with large subcortical terminals visualized by their selective marker, vesicular glutamate transporter 2 (vGLUT2). At the electron microscopic level vGLUT2-positive and large, labeled cortical terminals established synapses on the same relay cell. Large amplitude EPSPs from cortical and peripheral origin were recorded in the same Po cell in vivo.
Our data disclose a highly efficient but rapidly depressing cortical drive in HO nuclei in vivo. The convergence of peripheral and cortical driver input on the same cell suggests that these relays may serve as AND gates with output determined by the temporal coincidence of cortical and peripheral inputs.
Conference:
IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010.
Presentation Type:
Poster Presentation
Topic:
Sensory and motor systems
Citation:
Bokor
H,
Groh
A,
Plattner
VM,
Hangya
B,
Bodor
Á,
Sakmann
B,
Deschenes
M and
Acsády
L
(2010). Nucleus specific cortical control in the thalamus of the rat, convergence of cortical and peripheral driver afferents.
Front. Neurosci.
Conference Abstract:
IBRO International Workshop 2010.
doi: 10.3389/conf.fnins.2010.10.00063
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Received:
21 Apr 2010;
Published Online:
21 Apr 2010.
*
Correspondence:
Hajnalka Bokor, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary, hbokor@koki.hu