Abstract
To investigate whether local field potential (LFP) levels may change in association with the learning stage, we analyzed LFPs from rat hippocampus (Hip) and prefrontal cortex (PFC) during operant discrimination reversal trainings. Rats were trained with initial discrimination task using light and sound (one for S+ and another for S-) as the discrimination stimuli until a stable discriminative performance was achieved. Then the rats received the reversal training. In this training, responses to S+ signal increased within 2-4 training sessions (early learning phase), whereas those to S- decreased at the late phase (4-8th sessions). LFP gamma-band powers showed an increase during training, which was significantly attenuated at the first training session in the Hip, and in the late learning phase in the PFC. These results suggest that LFP gamma-band powers change during the learning stage in the Hip and PFC differently. First exposure to the reversal training may depress Hip gamma-band activity. The depression of PFC gamma-band activity may relate to inhibitory control in the late learning phase. [J Physiol Sci. 2006;56 Suppl:S192]
