, 2008; Bosman et al., 2009; Herrington et al., 2009; Hafed & Krauzlis, 2010), it may be the case that a system that biases when and where microsaccades are generated may provide optimum processing of peripheral visual locations during fixation. It would be interesting to explore whether and how individual microsaccades that are triggered in covert attention tasks may help to ‘regularise’ the pattern of neuronal activity in different brain areas, and how that ultimately influences behavior in the task. Z. M. Hafed was funded by the Werner
Reichardt Center for Integrative Neuroscience. L. P. Lovejoy was funded by the Institute for Neural Selleckchem BMS-734016 Computation and the Aginsky Scholars Award Program. R. J. Krauzlis was funded by the National Institutes of Health (Grant EY12212) and the National Eye Institute Intramural Research Program at the National Institutes of Health. “
ventrobasal (VB) thalamus contains a relatively uniform population of thalamocortical (TC) neurons that receive glutamatergic input from the vibrissae and the somatosensory cortex, and inhibitory input from the nucleus reticularis thalami (nRT). In this study we describe γ-aminobutyric acid (GABA)A receptor-dependent slow outward currents (SOCs) in TC neurons that are distinct from fast inhibitory postsynaptic currents (IPSCs) and tonic Ganetespib currents. SOCs occurred spontaneously or could be evoked by hypo-osmotic stimulus, and were not blocked by tetrodotoxin, removal
of extracellular Ca2+ or bafilomycin A1, indicating a non-synaptic, non-vesicular GABA origin. SOCs were more common in TC neurons of the VB compared with the dorsal lateral geniculate nucleus, and were rarely observed in nRT neurons, whilst SOC frequency in the VB increased with age. Application of THIP, a selective agonist at δ-subunit-containing GABAA receptors, occluded SOCs, whereas the benzodiazepine site (-)-p-Bromotetramisole Oxalate inverse agonist β-CCB had no effect, but did inhibit spontaneous and evoked IPSCs. In addition, the occurrence of SOCs was reduced in mice lacking the δ-subunit, and their kinetics were also altered. The anti-epileptic drug vigabatrin increased SOC frequency in a time-dependent manner, but this effect was not due to reversal of GABA transporters. Together, these data indicate that SOCs in TC neurons arise from astrocytic GABA release, and are mediated by δ-subunit-containing GABAA receptors. Furthermore, these findings suggest that the therapeutic action of vigabatrin may occur through the augmentation of this astrocyte–neuron interaction, and highlight the importance of glial cells in CNS (patho) physiology.