Spatial navigation, episodic memory and context
processing: what does the hippocampus do?
Although the hippocampus has been the target of
intense scrutiny for nearly fifty years, there remains
considerable disagreement about the specific functional
contribution the hippocampus makes to learning and
memory processes. Two of the currently dominant theories
suggest that the hippocampus is specialized for spatial
navigation or for memory for personally experienced
events (episodic memory). However, recent findings
from our laboratory indicate that the hippocampus
is critically involved in processing contextual information.
Although the term 'context' has traditionally been
used to refer to the continuously present background
stimuli, we have shown that hippocampal neurons are
highly sensitive to abstract situational features
of the context, such as the task demands. For example,
hippocampal neurons exhibit markedly different firing
patterns when rats are required to perform different
behaviors in the same environment. Since these firing
patterns are unique to a given context, they could
serve as a neural representation of the context.
I will suggest that the hippocampal role in processing
spatial information is but one example of a broader
function of context processing and that the hippocampus
contributes to episodic memory by providing a neural
representation of the context, which is, by definition,
a critical component of episodic memory.