Hippocampal place cell activity can be influenced by behavioural context, including the task being performed, and past or future locations. For example, Ainge et al (J Neurosci, 2007 27:9769-79) showed that many CA1 place cells had goal-dependent prospective firing as rats performed a serial reversal task on a double Y-maze (where the choice arms of the initial Y each give rise to a second Y). In well trained rats, goal-dependent firing occurred before both the first and second Y choice points. However, it is not clear whether this activity is present from the outset, or emerges only after the task is well learned. To examine this, we recorded from CA1 place cells for the first 12+ days of training on the same double Y-maze. Each day, four blocks of 10-20 trials were run, with a different goal box rewarded on each block. We found that the proportion of place cells with prospective goal-dependent activity on the maze changed across training. On Day 1, different rats showed either little or no goal-dependent firing, and tended to perform badly on the task. Over the next few days, the proportion of cells with goal-dependent activity increased, either gradually across days, or in some cases abruptly. This increase was associated with increasingly accurate performance by the rats both in returning to the correct goal box during a block of trials, and in redirecting their choices to the new goal when the reward location switched. Interestingly, during later stages of training, and after performance reached asymptotic levels, the proportion of cells showing goal-dependent activity often decreased (although goal-dependent activity was still observed). These dynamic changes are consistent with a role for goal-dependent place cell activity during acquisition of the task, in that it emerges as the animals learn. They also suggest either that the neural basis for performance may change, and/or that fewer cells with goal-directed activity are required with overtraining.
|Publication status||Published - 2008|
|Event||6th FENS Forum of European Neuroscience - Geneva, Switzerland|
Duration: 12 Jul 2008 → 16 Jul 2008
|Conference||6th FENS Forum of European Neuroscience|
|Period||12/07/08 → 16/07/08|