The hippocampus is a brain region that has long been thought to be crucial for the formation of episodic memory. The well-established phenomenology of the hippocampus provides mechanisms through which it is capable of providing two of the three components thought to comprise an episodic engram. The spatially localised firing of neurons in region CA1 of the hippocampus have been thought to represent a “spatial map”, potentially providing a “where” component of episodic memory.
It has also been shown that the spatial firing of these neurons is malleable with respect to changing goals within an environment, possibly providing a “what” component. However, there is currently little data on how the hippocampus might represent the missing “when” component of the episodic memory code. In the experiments described here, hippocampal single units were initially recorded continuously for very long time periods. It was shown that the firing of these cells oscillated on a circadian frequency. Subsequent experiments using a variety of novel paradigms demonstrate that the oscillation in hippocampal activity is not restricted to the activity of single units, and that it is under the control of a motivational stimulus.
Together, the results of these experiments show that the hippocampus is capable of reflecting circadian time, and that it is possible that this activity is the missing episodic “when” component that a region responsible for forming these memories must reflect.
|Date||Wednesday, 20 February 2013|
|Time||1:00pm - 2:00pm|
|Location||William James Seminar Room, 103, 275 Leith Walk|
|Contact Name||Cara Duffy|
|Contact Phone||64 3 479 7645|