Cortical afferents onto the nucleus Reticularis thalami promote plasticity of low-threshold excitability through GluN2C-NMDARs

• Published in: Scientific reports 2017-09, Vol.7 (1), p.12271-13, Article 12271
• Main Authors: Fernandez, Laura M. J., Pellegrini, Chiara, Vantomme, Gil, Béard, Elidie, Lüthi, Anita, Astori, Simone
• Format: Article
• Language: English
• Subjects: 631/378/1385; 631/378/2591; 631/378/87; 64/110; 9/30; 9/74; Animals; Calcium channels; Calcium channels (T-type); Calcium Channels - metabolism; Cerebral cortex; Cerebral Cortex - physiology; Communication; Excitability; Glutamatergic transmission; Glutamic acid receptors (ionotropic); Humanities and Social Sciences; Information processing; Mice; multidisciplinary; N-Methyl-D-aspartic acid receptors; Neuronal Plasticity; Neurons - physiology; Neuroplasticity; Nuclei; Oscillations; Photoactivation; Receptors, N-Methyl-D-Aspartate - metabolism; Recruitment; Science; Science (multidisciplinary); Sensory integration; Sleep; Sleep and wakefulness; Somatosensory cortex; Spectral composition; Synapses; Thalamus; Thalamus - physiology
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-12552-8

Thalamus and cortex represent a highly integrated processing unit that elaborates sensory representations. Interposed between cortex and thalamus, the nucleus Reticularis thalami (nRt) receives strong cortical glutamatergic input and mediates top-down inhibitory feedback to thalamus. Despite growing appreciation that the nRt is integral for thalamocortical functions from sleep to attentional wakefulness, we still face considerable gaps in the synaptic bases for cortico-nRt communication and plastic regulation. Here, we examined modulation of nRt excitability by cortical synaptic drive in Ntsr1-Cre x ChR2 tg/+ mice expressing Channelrhodopsin2 in layer 6 corticothalamic cells. We found that cortico-nRt synapses express a major portion of NMDA receptors containing the GluN2C subunit (GluN2C-NMDARs). Upon repetitive photoactivation (10 Hz trains), GluN2C-NMDARs induced a long-term increase in nRt excitability involving a potentiated recruitment of T-type Ca 2+ channels. In anaesthetized mice, analogous stimulation of cortical afferents onto nRt produced long-lasting changes in cortical local field potentials (LFPs), with delta oscillations being augmented at the expense of slow oscillations. This shift in LFP spectral composition was sensitive to NMDAR blockade in the nRt. Our data reveal a novel mechanism involving plastic modification of synaptically recruited T-type Ca 2+ channels and nRt bursting and indicate a critical role for GluN2C-NMDARs in thalamocortical rhythmogenesis.