The authors used affective modulation of the eyeblink startle response to examine the impact of traumatic brain injury (TBI) on emotional reactions to pictures. Participants were 13 individuals with severe TBI and 24 controls. Participants were presented with pictures that differed in affective valence (e.g., mutilated bodies, erotic couples, and household objects) while the eyeblink startle re...

Evidence suggests that respiratory sinus arrhythmia (RSA) may be an important indicator of physiological flexibility. However, few studies have examined the relation between RSA and defensive habituation, a process contingent on physiological flexibility. In three independent samples, habituation was defined as the time course of 9 startle responses. In Sample one and two, startle was recorded ...

The hypothesis that the standard acoustic startle habituation paradigm contains the elements of Pavlovian fear conditioning was tested. In a potentiated startle response paradigm, a startle stimulus and a light conditioned stimulus (CS) were paired. A startle stimulus then was tested alone or following the CS. Freezing behavior was measured to index conditioned fear. The startle response was po...

Fear-potentiated startle (FPS) is an increasingly popular psychophysiological method for the objective assessment of fear and anxiety. Studies applying this method often elicit the startle reflex with loud white-noise stimuli. Such intense stimuli may, however, alter psychological processes of interest by creating unintended emotional or attentional artifacts. Additionally, loud acoustic probes...

The amygdala sends heavy and broad projections to the rostral midbrain including the periaqueductal gray (PAG), the deep layers of the superior colliculus/deep mesencephalic nucleus (deep SC/DpMe), and the lateral mesencephalic reticular formation (MRF) that in turn project to the nucleus reticularis pontis caudalis (PnC), an obligatory relay in the primary acoustic startle circuit. Chemical le...

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...

There has been a recent surge of interest in the development of animal models of hyperacusis, a condition in which tolerance to sounds of moderate and high intensities is diminished. The reasons for this decreased tolerance are likely multifactorial, but some major factors that contribute to hyperacusis are increased loudness perception and heightened sensitivity and/or responsiveness to sound....

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 ...

BACKGROUND Previous data in both rat and mouse genetic models suggest that there is a genetic relationship between acute alcohol withdrawal responses and innate alcohol drinking behavior. The purpose of the present study was to examine whether acute alcohol withdrawal responses, as measured by acoustic startle and prepulse inhibition (PPI) of acoustic startle, may be genetically related to inna...

The amplitude of the acoustic startle response is reliably enhanced when elicited in the presence of bright light (light-enhanced startle) or in the presence of cues previously paired with shock (fear-potentiated startle). Light-enhanced startle appears to reflect an unconditioned response to an anxiogenic stimulus, whereas fear-potentiated startle reflects a conditioned response to a fear-elic...