Abstinent alcoholics often denycraving for alcohol but still show a high level of relapse. The eyeblink response to startling noise was used as an indicator of the emotional response to alcohol-related, positive, negative and neutral visual stimuli in abstinent alcoholics, social drinkers and rarelydrinking controls. The cognitive evaluation of the stimuli was assessed byratings of subjective craving, valence and arousal. The startle response of the alcoholics to alcohol-related stimuli was significantlyinhibited despite an aversive overt stimulus-evaluation. These findings indicate that alcohol-related stimuli mayhave appetitive incentive salience for alcoholics in spite of verbal reports of craving and valence to the opposite.

Sensorimotor inhibition, or the ability to filter out excessive or irrelevant information, theoretically supports a variety of higher-level cognitive functions. Impaired inhibition may be associated with increased impulsive and risky behavior in everyday life. Individuals infected with HIV frequently show impairment on tests of neurocognitive function, but sensorimotor inhibition in this population has not been studied and may be a contributor to the profile of HIV-associated neurocognitive disorders (HAND). Thirty-seven HIV-infected individuals (15 with HAND) and 48 non-infected comparison subjects were assessed for prepulse inhibition (PPI), an eyeblink startle paradigm measuring sensorimotor gating. Although HIV status alone was not associated with PPI deficits, HIV-positive participants meeting criteria for HAND showed impaired PPI compared to cognitively intact HIV-positive subjects. In HIV-positive subjects, PPI was correlated with working memory but was not associated with antiretroviral therapy or illness factors. In conclusion, sensorimotor disinhibition in HIV accompanies deficits in higher-order cognitive functions, although the causal direction of this relationship requires investigation. Subsequent research on the role of sensorimotor gating on decision-making and risk behaviors in HIV may be indicated. (JINS, 2013, 19, 1–9)

The present study evaluated the ability of a weak electrical prepulse to modify startle caused by a more intense shock. Painful electrical shocks (150 V, 0.5 ms duration) were presented to the upper arm of college student participants, preceded on some trials by a weaker shock (0.5 ms duration, at perceptual threshold) at the same location. Intense shocks elicited eyeblink reflexes, and these eyeblinks were inhibited by weak electrical prepulses. These data suggest that the inclusion of prepulses immediately preceding painful therapeutic shocks, such as those generated by an implanted cardioverter-defibrillator, might be capable of reducing the startle response generated by that therapeutic shock.

Conditioned inhibition of classical conditioning was investigated with the startle reflex and the skin conductance response (SCR) in humans using a serial presentation of the conditioned inhibitor (X) and of the conditioned stimulus (CS). The unconditioned stimulus (US) was a shock. During conditioning, participants were presented with two different reinforced CS (A, B) and with X preceding A (noted X → A). During X → A, A was not reinforced with the US. During the summation test, B, X → B, and Y → B were presented (Y was a new stimulus that tested the specificity of the inhibitory properties of X). B was not reinforced during the summation test. A, B, X, and Y were lights of different colors. Participants were divided into a low and a high anxious group based on the TPQ (C.R. Cloninger, 1987). In the low anxious group, conditioned startle potentiation and SCR responses to A were inhibited when X preceded A (noted AXA). This differential responding to A and AXA emerged earlier with the SCR than with startle. During the summation test, the inhibitory properties of X did not transfer to B. In the high anxious group, there was only a differential SCR to A and AXA. X did not inhibit startle potentiation to A.

Contextual fear conditioning was examined using the startle reflex in two groups of participants over two sessions separated by 1/2 h. The conditioned stimulus (CS) was paired (paired group) or not (unpaired group) with an unpleasant shock during conditioning. The paired group showed conditioning to the CS that was well retained over the retention interval. Session 1 intertrial interval startles—a measure of contextual conditioning—were greater in the unpaired compared to the paired group. Context conditioning was retained in Session 2 and was present before the shock electrodes were attached. Self-rating of state anxiety, arousal, and pleasure indicated differential changes in mood from Session 1 to Session 2 in the two groups, with the unpaired group showing relatively greater negative affects compared to the paired group. These results indicate that unpredictable shocks lead to greater context conditioning as measured by startle and self-reports.

Affective reactions to briefly presented pictures were investigated to determine whether fleeting stimuli engage the motivational systems mediating emotional responses. Emotional and neutral pictures were presented for 500 ms; heart rate, skin conductance, corrugator EMG, and the evoked startle reflex were measured. The time course of reflex modulation was similar to that obtained with longer (6 s) presentations, suggesting that picture processing continues in the absence of a sensory stimulus. Affective reactions found with more sustained presentation were also obtained, with more corrugator EMG activity for unpleasant pictures, and greater skin conductance reactivity for emotional pictures. Heart rate modulation, however, appears to rely on the presence of a sensory stimulus. The data also suggest that brief presentations of unpleasant pictures may result in less defensive activation than sustained presentation.

Many studies have shown a consistent pattern in adults' responses to affective pictures and there is growing evidence of gender differences, as well. Little is known, though, about children's verbal, behavioral, and physiological responses to affective pictures. Two experiments investigated children's responses to pictures. In Experiment 1, children, adolescents, and adults viewed pictures varying in affective content and rated them for pleasure, arousal, and dominance. Results indicated that children and adolescents rated the pictures similarly to adults. In Experiment 2, physiological responses, self-report, and viewing time were measured while children viewed affective pictures. As with adults, children's responses reflected the affective content of the pictures. Gender differences in affective evaluations, corrugator activity, skin conductance, startle modulation, and viewing time indicated that girls were generally more reactive to unpleasant materials.

The effectiveness of different types of auditory prepulses in eliciting skin conductance orienting and in producing prepulse inhibition (PPI) of the acoustic startle eyeblink was studied in two experiments. A discrete white noise prepulse produced greater PPI than either a continuous white noise, a discrete tone, or a continuous tone. The discrete white noise advantage was not due to similarity in bandwidth to the startle pulse or to a refractory effect of the prepulse. Moreover, a dissociation between PPI and skin conductance orienting was seen in both experiments. PPI using auditory prepulses appears to be dependent primarily on the acoustic characteristics of the transient portion of the prepulse, whereas skin conductance orienting is more dependent on the sustained portions of the stimulus.

The present study investigated the effects of lead stimulus modality on modification of the acoustic startle reflex during three reaction time tasks. In Experiment 1, participants (N = 48) were required to press a button at the offset of one stimulus (task relevant) and to ignore presentations of a second (task irrelevant). Two tones that differed in pitch or two lights served as signal stimuli. Blink startle was elicited during some of the stimuli and during interstimulus intervals. Skin conductance responses were larger during task-relevant stimuli in both groups. Larger blink facilitation during task-relevant stimuli was found only in the group presented with auditory stimuli, whereas larger blink latency shortening during task-relevant stimuli was found in both groups. Experiment 2 (N = 32) used only a task-relevant stimulus. Blink magnitude facilitation was significant only in the group presented with tones, whereas blink latency shortening was significant in both groups. Experiment 3 (N = 80) used a go/nogo task that required participants to press a button if one element of a compound stimulus ended before the second, but not if the asynchrony was reversed. The offset asynchrony was varied between groups as a manipulation of task difficulty. Startle magnitude facilitation was larger during acoustic than during visual stimuli and larger in the easy condition. The present data indicate that startle facilitation in a reaction time task is affected by stimulus modality and by task demands. The effects of the task demands seem to be independent of lead stimulus modality.

Participants in Experiments 1 and 2 performed a discrimination and counting task to assess the effect of lead stimulus modality on attentional modification of the acoustic startle reflex. Modality of the discrimination stimuli was changed across subjects. Electrodermal responses were larger during task-relevant stimuli than during task-irrelevant stimuli in all conditions. Larger blink magnitude facilitation was found during auditory and visual task-relevant stimuli, but not for tactile stimuli. Experiment 3 used acoustic, visual, and tactile conditioned stimuli (CSs) in differential conditioning with an aversive unconditioned stimulus (US). Startle magnitude facilitation and electrodermal responses were larger during a CS that preceded the US than during a CS that was presented alone regardless of lead stimulus modality. Although not unequivocal, the present data pose problems for attentional accounts of blink modification that emphasize the importance of lead stimulus modality.

Participants in Experiments 1 and 2 performed a discrimination and counting task to assess the effect of lead stimulus modality on attentional modification of the acoustic startle reflex. Modality of the discrimination stimuli was changed across subjects. Electrodermal responses were larger during task-relevant stimuli than during task-irrelevant stimuli in all conditions. Larger blink magnitude facilitation was found during auditory and visual task-relevant stimuli, but not for tactile stimuli. Experiment 3 used acoustic, visual, and tactile conditioned stimuli (CSs) in differential conditioning with an aversive unconditioned stimulus (US). Startle magnitude facilitation and electrodermal responses were larger during a CS that preceded the US than during a CS that was presented alone regardless of lead stimulus modality. Although not unequivocal, the present data pose problems for attentional accounts of blink modification that emphasize the importance of lead stimulus modality.

Reflexive eyeblinks to a startle probe vary with the pleasantness of affective pictures, whereas the corresponding P300 varies with emotional arousal. The impact of attention to the probe on these effects was examined by varying task and probe type. Probes were either nonstartling tones or startling noises presented during affective picture viewing. Half the participants performed a task requiring attention to the probes; the other participants were told to ignore the probes. Blinks to the startle probe varied with picture pleasantness for both task and nontask conditions. In contrast, P300 magnitudes for both startle and tone probes were reduced during emotionally arousing pictures, irrespective of pleasantness, in task and nontask conditions. Further, attending to the startle probe prompted an augmentation of N100 during unpleasant pictures. The data suggest that affective modulation of probe responses reflects obligatory processes in picture perception.