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CUR Announces 2009 CUR/APF Psychology Fellowship Awardee

Blake Hedstrom, CUR/APF 2009 Summer Research Fellow, conducted research at St. Olaf Collge on the effects of ethanol and anesthesia on the firing of Head Direction cells (neurons with directional firing properties) under the supervision of Dr. Gary Muir
© David Gonnerman
Blake Hedstrom, Psychology Major at St. Olaf College has received the 2009 CUR/APF Psychology Fellowship Award.  Gary Muir, Associate Professor of Psychology served as Blake's mentor on the project.  St. Olaf college received a stipend of $3,500, and travel and supply reimbursement up to $1,000.  The abstract for Blake's final project, The Effects of Ethanol on Head Direction Cell Activity and Spatial Reorientation in the Freely-Moving Rat is included below.


Head direction (HD) cells in the freely-moving rat fire as a function of the animal’s head
direction in the horizontal plane, and are thought to be an integral component of a spatial
navigation system encoding directional heading. To examine the effects of ethanol and
Nembutal anesthesia on HD cells, single units (n=23) were recorded from the anterodorsal
thalamic nucleus (ADN) of two male sprague-dawley rats and three female Long-
Evans rats while they foraged freely in a cylinder. Under high doses of Ethanol (3g/kg,
2g/kg,1.5g/kg, and 1.0g/kg) or Nembutal (25mg/kg), HD cells would begin to fire nondirectionally while the animal was immobile. This loss of directionality was
accompanied by desynchronized hippocampal EEG of decreased amplitude, and an
absence of theta rhythm, indicative of a loss of consciousness or sleep. A decrease in the
HD cell’s firing rate was also seen when the animal was immobile in the cell’s preferred
firing direction. Under 1g/kg Ethanol, HD cells fired in a stable, directional manner
while the animal was actively moving. While immobile for several seconds, however,
HD cell firing also became non-directional. This random, non-directional firing during
periods of unconsciousness or sleep may represent a loss of the directional signal within
the HD cell network under these conditions.

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