The effect of water maze spatial training on posterior parietal cortex transcallosal evoked field potentials in the rat.

Long-term potentiation (LTP) is the principal model of synaptic plasticity often used to explain the changes that occur in the brain as a result of learning and memory. In this experiment the relationship between rat posterior parietal cortex (PPC) transcallosal evoked field potentials (TCEPs) and spatial training in the water maze was examined to determine if LTP-like changes (i.e. learning-induced LTP) in PPC TCEPs occur as a result of spatial training. Spatial training consisted of 10 trials per day for 10 consecutive days. The location of the hidden platform was changed over the course of spatial training to ensure the rats' acquisition of several different platform positions. TCEPs were taken 1 and 23 h after each training session. Upon completion of all water maze training, the animals were administered LTP-inducing trains to ensure that the recording arrangement and procedure was capable of detecting LTP. The results showed that the rats quickly acquired the water maze task and that the recording arrangement and procedure were capable of detecting LTP, even after the first session of induction. However, despite robust place learning, the TCEPs taken after water maze training did not differ from those taken before water maze training. Although the present results failed to provide any evidence for a role of neocortical LTP in learning and memory, further studies of this nature are required to determine if the present results generalize to different behavioural tasks and/or cortical areas.