Publication Date


Document Type


Committee Members

Dragana Claflin (Committee Member), Michael Hennessy (Committee Chair), Larry Ream (Committee Member), Patricia Schiml (Committee Co-chair)

Degree Name

Master of Science (MS)


Maternal separation has been shown to promote the onset of depression. This early life stressor produces a biphasic response marked by an active "protest" phase followed by a passive "despair" phase in humans as well as several other species. In infant guinea pigs, active phase behaviors include increased locomotion and species-typical distress vocalizations, whereas the passive phase is marked by depressive-like behaviors including a crouched stance, eye-closure and extensive piloerection. The mechanism underlying the transition from one phase to the next is still unknown. The purpose of this study was to determine if daily stimulation of the neural pathway initiating the active behaviors would lead to enhanced expression of the passive behaviors. Guinea pigs were separated into experimental and control groups. The control group received daily stimulation of a brain region not anticipated to produce vocalizations (cortex) while the experimental group received daily stimulation of the periaqueductal grey (PAG). Although stimulation of the PAG produced vocalizations that decreased across the 10 days of testing, the PAG stimulated animals did not show more passive depressive-like behaviors than pups receiving control-region stimulation.

Page Count


Department or Program

Department of Neuroscience, Cell Biology & Physiology

Year Degree Awarded


Included in

Anatomy Commons