Faculty Collaboration Database

Lesions of the periaqueductal gray and rostral ventromedial medulla disrupt antinociceptive but not cardiovascular aversive conditional responses. J Neurosci 1994 Nov;14(11 Pt 2):7099-108

Date

11/01/1994

Pubmed ID

7965101

Pubmed Central ID

PMC6577286

DOI

10.1523/JNEUROSCI.14-11-07099.1994

Scopus ID

2-s2.0-0028072774 (requires institutional sign-in at Scopus site)   85 Citations

Abstract

The presentation of an auditory stimulus that signals a noxious event such as foot shock results in the simultaneous expression of multiple aversive conditional responses (CRs), which include a transient elevation of arterial blood pressure (ABP) and an opioid-mediated form of hypoalgesia. Recent evidence suggests that the neural circuits responsible for the expression of these two aversive responses may overlap. In the present study, rats were trained using a Pavlovian fear conditioning paradigm in which white noise was repeatedly paired with shock. After training, groups of animals received electrolytic lesions centered in the dorsal or ventral periaqueductal gray (PAG) or in the medial or lateral rostral medulla. In sham-lesioned animals that were given paired presentations of noise and shock, subsequent presentation of the auditory stimulus caused a significant transient elevation of ABP and time-dependent inhibition of the tail flick reflex evoked by radiant heat. Lesions of either the dorsal or the ventral PAG blocked the antinociceptive CR but did not significantly affect ABP responses. Lesions of the ventromedial, but not the lateral, rostral medulla blocked hypoalgesia. Rostral medullary lesions did not reliably affect stimulus-evoked cardiovascular responses or baseline ABP. These results indicate that antinociceptive and cardiovascular conditional responses are anatomically dissociable and support our proposal that conditional hypoalgesia is mediated by a serial neural circuit that includes the amygdala, PAG, and rostral ventromedial medulla.

Author List

Helmstetter FJ, Tershner SA

Author

Fred Helmstetter PhD Professor in the Psychology / Neuroscience department at University of Wisconsin - Milwaukee

MESH terms used to index this publication - Major topics in bold

Animals
Association Learning
Blood Pressure
Conditioning, Classical
Electroshock
Fear
Male
Medulla Oblongata
Nociceptors
Periaqueductal Gray
Rats