Activity in barrel cortex related to tactile delay eyeblink conditioning

While implicit learning is thought to be responsible to generate conditioned responses (CRs) in Pavlovian delay paradigms, like delay eye blink conditioning (DEBC), explicit memory processes may be involved to learn the same contingencies, but store them for other purposes. Here, we investigated the engagement of the cortex in the supposedly non-cortical learning paradigm DEBC, using a single whisker deflection in head-fixed mice as the conditioned stimulus (CS). Spike responses in the primary somatosensory cortex (barrel cortex) showed two distinct changes. The first, a dip-peak pattern of firing-rate in response to CS, appeared many trials after the learned generation of CRs, while the second, a general decrement of firing in response to the CS, was tightly related to the time course of CR learning. The second effect matches previous findings using the cortex-dependent trace variant of eyeblink conditioning, while the first points to a learning-related cortical response that is independent from implicit learning and may well correspond to other types of learning. We hold this result as a first step to elucidate and disentangle neuronal underpinnings of multiple cooperative learning systems, commonly engaged even by the simplest forms of learning.