Vibrissa-Signaled Eyeblink Conditioning Induces Somatosensory Cortical Plasticity

Abstract

Whisker deflection conditioned stimuli (CS) were demonstrated to activate physiologically and anatomically defined barrels in the contralateral somatosensory cortex and to support trace-eyeblink conditioned responses when paired with corneal airpuff unconditioned stimuli in rabbits. Analysis of cytochrome-oxidase-stained somatosensory whisker-associated cortical barrels revealed a row-specific expansion of the conditioned compared with the nontrained hemisphere. This expansion was not evident in pseudo-conditioned rabbits, suggesting that this expansion of conditioned cortical barrels in response to a hippocampal- and forebrain-dependent learning task (trace conditioning) is associative rather than activity dependent. Using whisker stimulation as a CS in the well studied eyeblink conditioning paradigm will facilitate characterizing sensory cortical involvement in controlling and modulating an associatively learned response at the neural systems and cellular level.