The Journal of Neuroscience, October 1, 2002, 22(19):8754-8761
New Intrathalamic Pathways Allowing Modality-Related and
Cross-Modality Switching in the Dorsal Thalamus
John W.
Crabtree and
John T. R.
Isaac
Medical Research Council Centre for Synaptic Plasticity, Department
of Anatomy, School of Medical Sciences, University of Bristol, Bristol
BS8 1TD, United Kingdom
Transmission through the dorsal thalamus involves nuclei that
convey different aspects of sensory or motor information. Cells in the
dorsal thalamus are strongly inhibited by the GABAergic cells of the
thalamic reticular nucleus (TRN). Here we show that stimulation of
cells in specific dorsal thalamic nuclei evokes robust IPSCs or
IPSPs in other specific dorsal thalamic nuclei and vice versa.
These IPSCs are GABAA receptor-mediated currents and are
consistent with the activation of disynaptic intrathalamic pathways
mediated by TRN. Thus, cells engaged in sensory analyses in the
ventrobasal complex or the medial division of the posterior complex can
interact with cells responsive to sensory events in the caudal
intralaminar nuclei, whereas cells engaged in motor analyses in the
ventrolateral nucleus can interact with cells responsive to motor
events in the rostral intralaminar nuclei. Furthermore, sensory
event-related cells in the caudal intralaminar nuclei can interact with
motor event-related cells in the rostral intralaminar nuclei. In
addition, single cells in one dorsal thalamic nucleus can receive
convergent inhibitory inputs after stimulation of cells in two or more
other dorsal thalamic nuclei, and TRN-mediated inhibitory inputs can
momentarily switch off tonic firing of action potentials in dorsal
thalamic cells. Our findings provide the first direct evidence for a
rich network of intrathalamic pathways that allows modality-related and
cross-modality inhibitory modulation between dorsal thalamic nuclei.
Moreover, TRN-mediated switching between dorsal thalamic nuclei could
provide a mechanism for the selection of competing transmissions of
sensory and/or motor information through the dorsal thalamus.
Key words:
thalamic reticular nucleus; intrathalamic pathways; IPSCs; IPSPs; GABAA receptors; convergent inhibitory
inputs; modality-related and cross-modality modulation; selective
attention
Copyright © 2002 Society for Neuroscience 0270-6474/02/22198754-08$05.00/0
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