Theta activity attenuation correlates with avoidance learning progress in gerbils.

Changes of cortical activity were examined with electrocorticograms sampled from gerbils during learning. Animals were subjected to tone-conditioned avoidance training in a shuttle-box. Electrocorticograms were recorded from an electrode placed over medial prefrontal cortex. Temporal patterns of theta activity were analyzed across 180 successive trials. With the start of conditioning strong theta activity occurred in each trial in the phase immediately after hurdle crossing. With reliable occurrence of conditioned responses, that is at the stage of retrieval of the avoidance response, the theta activity became reduced. A negative correlation exists between the theta power and the development of learning progress. Theta reduction thus could reflect decreasing demands on information processing in the course of avoidance success monitoring across trials.