Submitted on October 9, 2008
Revised on December 8, 2008
Accepted on December 8, 2008
Slow recovery from excitation of thalamic reticular nucleus neurons
Xiongjie Yu1, Xinxiu Xu1, Xi Chen2, Shigang He1, and Jufang He2*
1 Institute of Biophysics
2 The Hong Kong Polytechnic University
* To whom correspondence should be addressed. E-mail: rsjufang{at}polyu.edu.hk.
Responses to repeated auditory stimuli were examined in 103 neurons in the auditory region of the thalamic reticular nucleus (TRN) and in 20 medial geniculate (MGB) neurons of anesthetized rats. A further 6 TRN neurons were recorded from awake rats. The TRN neurons showed strong responses to the first trial and weak responses to the subsequent trials of repeated auditory stimuli and electrical stimulation of the MGB and auditory cortex, when the inter-stimulus interval (ISI) was short (< 3 s). They responded to the second trial when the inter-stimulus interval was lengthened to 3 s or greater. These responses contrasted to those of MGB neurons, which responded to repeated auditory stimuli of different ISIs. The TRN neurons showed a significant increase in the onset auditory response from 9.5 Hz to 76.5 Hz when the ISI was increased from 200 ms to 10 s (p < 0.001, ANOVA). The duration of the auditory-evoked oscillation was longer when the ISI was lengthened. The slow recovery of the TRN neurons after oscillation of burst firings to fast repetitive stimulus was a reflection of a different role than that of the thalamocortical relay neurons. Supposedly the TRN is involved in the process of attention such as attention shift, the slow recovery of TRN neurons probably limits the frequent change of the attention in a fast rhythm.
