1 Introduction The processing of sensory information by the central nervous system is dif?cult to understand by the complex interconnections between subcortical and cortical areas. Connections between the thalamus and cortex are largely reciprocal, with information being processed in both feed-forward (periphery to thalamus to c- tex) and feedback (corticothalamic) directions. Sensory signals reach the cerebral cortex after having made synapses in different relay stations along the sensory pa- way. Classically, excitatory and inhibitory actions have been thought to modulate sensory responses...