A series of experiments was performed to determine whether long-term habituation of the acoustic startle response in rats is mediated by conditioned associations between contextual cues and the test stimulus. Experiment 1 established parameters yielding demonstrable long-term habituation of the startle response. Experiment 2 attempted to overshadow the hypothesized associations to contextual cu...

This study explored the time course of conditioned fear response expression. Two neutral male facial expressions served as conditioned stimuli (CS) in a differential trace conditioning that involved either an aversive (n=14) or a nonaversive (n=12) unconditioned stimulus (UCS) in a between-subjects design. Skin conductance response (SCR) to the CSs and startle response magnitudes to acoustic pr...

BACKGROUND Heightened startle response is a symptom of PTSD, but evidence for exaggerated startle in PTSD is inconsistent. This prospective study aimed to clarify whether altered startle reactivity represents a trait risk-factor for developing PTSD or a marker of current PTSD symptoms. METHODS Marines and Navy Corpsmen were assessed before (n = 2,571) and after (n = 1,632) deployments to Iraq...

Fear of certain threat and anxiety about uncertain threat are distinct emotions with unique behavioral, cognitive-attentional, and neuroanatomical components. Both anxiety and fear can be studied in the laboratory by measuring the potentiation of the startle reflex. The startle reflex is a defensive reflex that is potentiated when an organism is threatened and the need for defense is high. The ...

High doses of salicylate, the anti-inflammatory component of aspirin, induce transient tinnitus and hearing loss. Systemic injection of 250 mg/kg of salicylate, a dose that reliably induces tinnitus in rats, significantly reduced the sound evoked output of the rat cochlea. Paradoxically, salicylate significantly increased the amplitude of the sound-evoked field potential from the auditory corte...

BACKGROUND Prepulse inhibition of the startle reflex response refers to the ability of a weak prestimulus to transiently inhibit the response to a closely following strong sensory stimulus. This effect represents an operational index of sensorimotor gating and is found to be deficient in schizophrenia. Prepulse inhibition deficits in schizophrenia seem to be partially normalized by typical anti...

Unexpected support-surface movements delivered during stance elicit "first trial" postural reactions, which are larger and cause greater instability compared with habituated responses. The nature of this first trial reaction remains unknown. We hypothesized that first trial postural reactions consist of a generalized startle reaction, with a similar muscle synergy as the acoustic startle respon...

Frontotemporal lobar degeneration (FTLD) is a neurodegenerative disease associated with dramatic changes in emotion. The precise nature of these changes is not fully understood; however, we believe that the most salient losses relate to self-relevant processing. Thus, FTLD patients exhibit emotional changes that are consistent with a reduction in self-monitoring, self-awareness and the ability ...

BACKGROUND Criminal offenders with a diagnosis of psychopathy or borderline personality disorder (BPD) share an impulsive nature but tend to differ in their style of emotional response. This study aims to use multiple psychophysiologic measures to compare emotional responses to unpleasant and pleasant stimuli. METHODS Twenty-five psychopaths as defined by the Hare Psychopathy Checklist and 18...

we present an infant girl with hyperekplexia, hypertonia, hyperreflexia and a characteristic exaggerated response to nose tap. this disorder is important to recognize because of the increased risk of apnea and sudden infant death, this infant responded to clonazepam.