Biology Reference
In-Depth Information
the connections that associate certain places in the environment with the presence of goals
and as a result to modify the episodic sequence in hippocampal network.
Besides
hippocampus proper the subiculum also plays a role in the performance of a delayed-
nonmatch-to-sample short-term task (Hampson
et al.
, 2000).
Figure 4. Experience-dependent, goal-related
place field separation.
A. Representation of the firing
pattern of a neuron recorded during the first and second halves of the random reward session (Block 1
and Block 2). For each trial, rewards were placed at the end of randomly designated arms, and the rat
started at one of the three non-rewarded arms. The random reward session was also divided into 2
blocks of trials, although all of the trials consisted of searching for randomly placed rewards, and the
neuronal responses were compared across these blocks. Since the task demands did not differ across
these 2 blocks, there was no context manipulation and the neuronal responses were not expected to
differ. B. Illustration of the context-specific firing patterns of neurons recorded during asymptotic
performance. In this experiment, rats were trained to retrieve rewards from one location on a plus maze
during the first half of each training session and from a different location in the same environment
during the second half of the sessions. The rats were given identical training sessions each day until
they reached a behavioral criterion of 75% correct choices. The two session halves constituted separate
contexts defined by their differing reward location. Left plot illustrates neuronal firing during the first
half of the session (Context A) when the reward was always placed on the east arm, and during the
second half (Context B) when the reward was always placed on the west arm. The differential responses
developed only in rats that were given context training and not in rats that were given repeated random
reward sessions, indicating that the context specific place fields could not have been due to factors
unrelated to learning to distinguish the contexts (adapted from (Smith & Mizumori, 2006a)).
