THE ACOUSTIC STARTLE RESPONSE IN RATS - CIRCUITS MEDIATING EVOCATION,INHIBITION AND POTENTIATION

This review describes the neuronal mechanisms underlying the mediation and modulation of the acoustic startle response (ASR) in rats. The co mbination of anatomical, physiological and behavioral methods has iden tified pathways which mediate and modulate the ASR. The ASR is mediate d by a relatively simple, oligosynaptic pathway located in the lower b rainstem which activates spinal and cranial motor neurons. An importan t element of the pathway which mediates the ASR is the caudal nucleus of the pontine reticular formation (PnC). Interestingly, this nucleus is also the target of input from various brain nuclei which are involv ed in the modulation (e.g. fear-potentiation, sensitization, habituati on, prepulse inhibition and pleasure-attenuation) of the ASR; Hence, t he PnC can be described as a sensorimotor interface, when the transiti on of sensory input into the motor output can be directly influenced b y excitatory or inhibitory afferents. On the basis of these facts we c onclude that the ASR map be a valuable model for the study of general principles of sensorimotor-motivational information processing at the behavioral and neurophysiological level in mammals. (C) 1997 Elsevier Science B.V.