Startle Reaction: Modification by Background Acoustic Stimulation

Abstract

Six rats were exposed to a sequence of gunshot-like acoustical bursts during silence, during steady noise, and during pulsed noise. Assessment of their startle reactions to the bursts revealed that a background of steady noise enhanced the response, whereas a background of pulsed noise produced suppression of response. It is hypothesized that pulsed noise causes a relative refractory state in the mechanisms responsible for startle and that steady noise may enhance startle by masking uncontrolled punctiform acoustic stimuli.

The effect of qualitative differences in audio stimuli and backgrounds in instrumental escape conditioning

“…On the other hand, Perkins (1953) cites data from Bragiel (1953) which indicates that stimulus intensity effects may be due to stimulus-background contrast. This leads to predictions opposite to those drawn from Hoffman et al (1963Hoffman et al ( , 1965 in the case of the two white-noise stimulus conditions mentioned above. However, they both would predict a buzzer stimulus to Psychon.…”

Differential Effects of Acute Serotonin and Dopamine Depletion on Prepulse Inhibition and P50 Suppression Measures of Sensorimotor and Sensory Gating in Humans

“…PPI of the startle reflex refers to an attenuation of this startle reflex that occurs when the evoking stimulus is preceded by a non-startling 'prepulse' by approximately 30-500 ms (Graham, 1975;Hoffman and Fleshler, 1963;Ison et al, 1973). In humans, the startle reflex is typically measured via the electrical activity of the orbicularis oculi muscle using electromyography (EMG) (Graham, 1975), and the PPI is typically calculated as a percentage score of the reduction in magnitude of this measure of the startle reflex, with maximal inhibition generally observed with 'lead intervals' of approximately 120 ms (Graham, 1975;Hoffman and Fleshler, 1963;Ison et al, 1973).…”

“…PPI of the startle reflex refers to an attenuation of this startle reflex that occurs when the evoking stimulus is preceded by a non-startling 'prepulse' by approximately 30-500 ms (Graham, 1975;Hoffman and Fleshler, 1963;Ison et al, 1973). In humans, the startle reflex is typically measured via the electrical activity of the orbicularis oculi muscle using electromyography (EMG) (Graham, 1975), and the PPI is typically calculated as a percentage score of the reduction in magnitude of this measure of the startle reflex, with maximal inhibition generally observed with 'lead intervals' of approximately 120 ms (Graham, 1975;Hoffman and Fleshler, 1963;Ison et al, 1973). It has now been well documented that patients with schizophrenia display a deficit in PPI (for a review see Cadenhead and Braff, 1999;Braff et al, 2001Braff et al, , 2007, which is interpreted as reflecting a failure of 'sensorimotor gating' (Braff and Geyer, 1990), and which may be normalized with the use of atypical antipsychotic drugs (Weike et al, 2000;Hamm et al, 2001;Kumari and Sharma, 2002;Kumari et al, 2007).…”

On again, off again effects of gonadectomy on the acoustic startle reflex in adult male rats

“…aromatase; prepulse inhibition; sensorimotor gating; estrogen; androgen Numerous studies that have measured the acoustic startle reflex (ASR) and/or its prepulse inhibition (PPI) in humans, human patient populations and laboratory animals [1,2,3,4] have made clear that the ASR, the short-latency, whole body motor reflex elicited in response to a brief, intense acoustic pulse [5], and its PPI, operationally defined as the decrease in the ASR that occurs when the pulse stimulus is preceded by a weaker tone [6,7,8] reflect elements of behavior that are mediated by different brain regions and circuits [4,5,9 and that are in some cases influenced by different sets of neurotransmitters and neuromodulators [10]. Recent evidence suggests, however, that both may be sensitive to gonadal hormones.…”