Considering the corresponding time courses of inhibition exerted on thalamo-cortical neurons, tonic mode may thereby facilitate rapid changes in thalamo-cortical signaling, while burst mode may permit an initially strong evoked response from thalamo-cortical neurons (Hartings et al., 2003).
TRN neurons are critically involved in initiating Neratinib price and sustaining thalamo-cortical oscillations. For example, a deafferented TRN is able to self-generate oscillations in the 7–15 Hz range (spindles; Steriade et al., 1987). Moreover, interactions between TRN and thalamo-cortical neurons sustain oscillations—that is, TRN neurons inhibit thalamo-cortical neurons, which rebound fire to excite TRN neurons, thereby initiating another oscillatory cycle (Steriade et al., 1993). In addition to its prominent role in spindle generation, the TRN has been shown to oscillate PS-341 ic50 at lower (Amzica et al., 1992) and higher frequencies, including the
beta/gamma frequency range (Pinault and Deschênes, 1992). These different oscillation frequencies manifest during different behavioral contexts. Spindles and lower frequencies commonly occur during states of low vigilance, while beta/gamma frequencies are more associated with increased vigilance (Steriade et al., 1993). It appears that spindle oscillations may contribute to reduced efficacy of information transfer across retino-thalamic synapses, by decorrelating retinal input from thalamic output (Le Masson et al., 2002). A more specific role of response modes and oscillatory TRN activity in cognitive and perceptual tasks remains
to be defined. TRN neurons may influence thalamo-cortical neurons of the LGN and pulvinar in a number of ways. First, TRN neurons reduce the spike rate of thalamo-cortical neurons through direct inhibition. For example, the responses of TRN neurons evoked by stimuli at unattended locations were shown to increase, while the responses of LGN neurons decreased (McAlonan et al., 2008), thus suppressing thalamo-cortical transmission of information at unattended locations. Megestrol Acetate In the case of an attended visual stimulus, the converse response pattern was found—that is, responses of LGN neurons increased, while the responses of TRN neurons decreased, thus facilitating the transmission of information at attended locations. Such an inverse correlation has also been reported in anesthetized cats between simultaneously recorded neurons in the LGN and the perigeniculate nucleus, the equivalent of the TRN’s visual sector in the cat (Funke and Eysel, 1998). Second, it is possible that TRN neurons increase the responses of thalamo-cortical neurons through disinhibition. Disinhibition of thalamo-cortical neurons has been shown to arise from TRN neurons inhibiting other TRN cells via dendrodendritic synapses (Pinault et al.