1. The effects of lesions of the bed nucleus of the stria terminalis (BST) on the acquisition of conditioned fear were examined. In Experiment 1, BST lesions did not block acquisition of fear-potentiated startle to an explicit visual conditioned stimulus (CS) over 20 days of training. However, BST lesions blocked a gradual elevation in baseline startle also seen over the course of training. 2. The gradual increase in baseline startle was replicated in Experiment 2 without the presence of an explicit CS, using unoperated subjects. Experiment 2 showed that the elevation was due to repetitive exposure to shock, because unshocked control subjects did not show any elevation over sessions. 3. I Experiment 3, lesions of the BST did not disrupt rapid sensitization of the startle reflex by footshock, showing that different neural substrates underlie sensitization of startle by acute and chronic exposure to footshock. 4. These data indicate that the BST, despite its anatomical continuity with the amygdala, is not critically involved in the acquisition of conditioned fear to an explicit CS. Nevertheless, the BST is involved in mediating a stress-induced elevation in the startle reflex. This suggests that the BST and the CeA, which constitute part of the 'extended amygdala' have complementary roles in response to stress.
|Original language||English (US)|
|Number of pages||24|
|Journal||Progress in Neuro-Psychopharmacology and Biological Psychiatry|
|State||Published - May 1998|
Bibliographical noteFunding Information:
This research was supported by grants from the National Institute of Mental Health MH-00004, MH-11370, MH-19951, and MH-47840, and a grant from the Air Force Office of Scientific Research F49620.
- Bed nucleus
- Stria terminalis