Electrical Brain Stimulation and Depressive-like Behavior in Guinea Pigs

Maternal separation in guinea pigs produces a biphasic response consisting of an active behavior phase (vocalizations and locomotor activity) followed by a phase of passive depressive-like behavior (crouched stance, piloerection, and eye closure). The mechanism for the transition from the active to the passive phase is unknown. One suggestion is that continual activity of neural circuitry producing active behavior eventually leads to the expression of passive behaviors. The purpose of this study was to test this possibility. Guinea pigs were assigned to experimental and control groups. The experimental group received daily stimulation of the bed nucleus stria terminalis (BNST) to produce vocalizations. Controls included non-operated animals and those which received daily electrical stimulation of a brain area not expected to produce vocalization (parietal cortex). Stimulation of the BNST elicited vocalizations, which decreased across 10 days of testing. However, BNST-stimulated animals did not show more passive depressive-like behavior than the controls