The chronometry of affective startle modulation in unipolar depression.

Affective startle eyeblink modulation by unipolar depressed and nondepressed participants was assessed during the anticipation and viewing of emotional pictures. Anticipatory startle probes were presented at 2,000 ms and 750 ms before picture onset. Startle probes during picture viewing were presented at 300 ms and 3,500-4,500 ms after picture onset. Although nondepressed participants demonstrated the predicted quadratic and linear patterns of responding in the 2,000-ms anticipatory and 3,500-4,500-ms viewing conditions, respectively, depressed participants were not significantly responsive to differences among picture valence categories at these probe conditions. There were no between-groups differences in startle modulation at the other two probe intervals, in picture ratings, or in behavioral responses to pictures. There was also little evidence of hyperresponsivity to negatively valenced stimuli in the depressed group. These results indicate that depression-related affective hyporesponsivity extended to startle modulation but that the nature and magnitude of the differences between depressed and nondepressed individuals were conditional on the specific cognitive and motivational processes recruited at different points in time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Trait emotions and affective modulation of the startle eyeblink: On the unique relationship of trait anger.

We examined relationships among individual differences in trait emotions and the emotion-modulated startle-eyeblink response. In particular, we examined the extent to which trait anger, which is negative in valence, would be associated with a pattern of approach motivation in startle eyeblink responses to appetitive stimuli. Self-reported trait emotions were compared with emotion-modulated startle eyeblink responses to auditory probes during appetitive, aversive, and neutral pictures. Results revealed that trait anger, enjoyment, and surprise were each associated with greater blink inhibition to appetitive pictures, indicating an approach motivational response. No other trait emotions were associated with startle eyeblink responses to appetitive or aversive pictures. These results support the idea that trait anger, although experienced as a negative emotion, is associated with an approach-related motivational response to appetitive stimuli at basic, reflexive levels of processing. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Individual differences in the activation and control of affective race bias as assessed by startle eyeblink response and self-report.

The activation and control of affective race bias were measured using startle eyeblink responses (Study 1) and self-reports (Study 2) as White American participants viewed White and Black faces. Individual differences in levels of bias were predicted using E. A. Plant and P. G. Devine's (1998) Internal and External Motivation to Respond Without Prejudice scales (IMS/EMS). Among high-IMS participants, those low in EMS exhibited less affective race bias in their blink responses than other participants. In contrast, both groups of high-IMS participants exhibited less affective race bias in self-reported responses compared with low-IMS participants. Results demonstrate individual differences in implicit affective race bias and suggest that controlled, belief-based processes are more effectively implemented in deliberative responses (e.g., self-reports). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexual orientation-related differences in prepulse inhibition of the human startle response.

Prepulse inhibition (PPI) refers to a reduction in the startle response to a strong sensory stimulus when this stimulus is preceded by a weaker stimulus--the prepulse. PPI reflects a nonlearned sensorimotor gating mechanism and also shows a robust gender difference, with women exhibiting lower PPI than men. The present study examined the eyeblink startle responses to acoustic stimuli of 59 healthy heterosexual and homosexual men and women. Homosexual women showed significantly masculinized PPI compared with heterosexual women, whereas no difference was observed in PPI between homosexual and heterosexual men. These data provide the first evidence for within-gender differences in basic sensorimotor gating mechanisms and implicate the known neural substrates of PPI in human sexual orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related positivity enhancement is not universal: Older Chinese look away from positive stimuli.

Socioemotional selectivity theory postulates that with age, people are motivated to derive emotional meaning from life, leading them to pay more attention to positive relative to negative/neutral stimuli. The authors argue that cultures that differ in what they consider to be emotionally meaningful may show this preference to different extents. Using eye-tracking techniques, the authors compared visual attention toward emotional (happy, fearful, sad, and angry) and neutral facial expressions among 46 younger and 57 older Hong Kong Chinese. In contrast to prior Western findings, older but not younger Chinese looked away from happy facial expressions, suggesting that they do not show attentional preferences toward positive stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The human startle reflex and alcohol cue reactivity: Effects of early versus late abstinence.

This study investigated the human eyeblink startle reflex as a measure of alcohol cue reactivity. Alcohol-dependent participants early (n?=?36) and late (n?=?34) in abstinence received presentations of alcohol and water cues. Consistent with previous research, greater salivation and higher ratings of urge to drink occurred in response to the alcohol cues. Differential salivary and urge responding to alcohol versus water cues did not vary as a function of abstinence duration. Of special interest was the finding that startle response magnitudes were relatively elevated to alcohol cues, but only in individuals early in abstinence. Affective ratings of alcohol cues suggested that alcohol cues were perceived as aversive. Methodological and theoretical implications of the findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Loss of emotional experience after traumatic brain injury: Findings with the startle probe procedure.

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 response to an acoustic probe was measured. Startle amplitude was used to assess valence of emotional response, and startle latency was used to index interest in the pictures. Subjective ratings of the affect and arousal elicited by the various pictures were also obtained. TBI impaired startle potentiation to unpleasant pictures but not startle attenuation to pleasant pictures. Further, subjective ratings indicated that TBI participants found unpleasant pictures less arousing than did controls. The results are consistent with recent evidence of differential impairment in negative versus positive emotions after TBI and are discussed in relation to 2 competing explanations of startle modulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term retention of the classically conditioned eyeblink response in rats.

Retention of the classically conditioned eyeblink response in rats was tested with a conditioned stimulus (CS)-alone extinction test and 2 sessions of reacquisition training. Retention of the eyeblink conditioned response (CR) during both tests was highest 24 hrs and 1 mo after initial acquisition. Three months after initial acquisition, responding during the CS-alone test was at baseline, but there was significant savings during reacquisition. By 6 mo after initial acquisition, the memory for the eyeblink CR was not expressed in either test. The group differences in retention, despite initial acquisition of the eyeblink CR to equal levels, suggest that rat eyeblink conditioning may provide a useful behavioral model for studying the neural processes underlying memory retention and loss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences: A developmental study of discriminability and affective response.

"A sample of… children… ranging in age from 4 to 6 was studied with regard to capacity to discriminate age differences and affective responses to stimulus persons varying in age. Each S was presented with two sets of stimulus faces of heterogenous ages with instructions to rank the photographs in terms of age, preference, and attractiveness… . Progressive increase in age discriminability were noted from ages 4 to 5… [with] a ceiling… [at] 5 to 6. Affective judgments with increasing age were in the direction of a more positive response to the younger faces… [esthetic preferences] were influenced… by… sex of the subject and of the photograph set." From Psyc Abstracts 36:04:4HJ21K. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Divergent trajectories in the aging mind: Changes in working memory for affective versus visual information with age.

Working memory mediates the short-term maintenance of information. Virtually all empirical research on working memory involves investigations of working memory for verbal and visual information. Whereas aging is typically associated with a deficit in working memory for these types of information, recent findings suggestive of relatively well-preserved long-term memory for emotional information in older adults raise questions about working memory for emotional material. This study examined age differences in working memory for emotional versus visual information. Findings demonstrate that, despite an age-related deficit for the latter, working memory for emotion was unimpaired. Further, older adults exhibited superior performance on positive relative to negative emotion trials, whereas their younger counterparts exhibited the opposite pattern. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuronal correlates of conditioned inhibition of the eyeblink response in the anterior interpositus nucleus.

Conditioned inhibition (CI) of the rat eyeblink response and the neuronal correlates of CI in the cerebellar interpositus nucleus were examined in the present study. In Experiment 1, CI was established with a novel, 3-group design. In Experiment 2, neuronal activity in the anterior interpositus nucleus was recorded during CI training and testing. Each rat was given 2 training phases and then tested for CI with summation and retardation tests. Rats given CI training showed behavioral inhibition compared with rats in 2 control groups. Neuronal activity in the anterior interpositus nucleus correlated with behavioral responding during discrimination training and during the summation test. The results suggest that neurons in the cerebellar anterior interpositus nucleus may participate in the acquisition or expression of CI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The ontogeny of interstimulus interval (ISI) discrimination of the conditioned eyeblink response in rats.

Discrimination of the eyeblink conditioned response (CR) between conditioned stimuli (CSs) of different durations and modalities was examined across development in rats. Interstimulus interval (ISI) discrimination was evident at Postnatal Days 23-34 in Experiment 1, and earlier CR peak latencies and enhanced CR amplitudes were seen to the long CS in the ISI discrimination group relative to a control group receiving the short CS without reinforcement. Experiment 2 showed that early CR peak latencies and enhanced CR amplitudes to the long CS in the ISI discrimination group were due to associative pairing of the short CS and unconditioned stimulus. Experiment 3 demonstrated ISI discrimination in adults that was improved relative to younger subjects, but with no enhancement of CR amplitude to the long CS in the ISI discrimination group. Cerebellar cortical maturation may influence the ontogeny of CR timing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related changes in the integration of gaze direction and facial expressions of emotion.

Gaze direction influences younger adults' perception of emotional expressions, with direct gaze enhancing the perception of anger and joy, while averted gaze enhances the perception of fear. Age-related declines in emotion recognition and eye-gaze processing have been reported, indicating that there may be age-related changes in the ability to integrate these facial cues. As there is evidence of a positivity bias with age, age-related difficulties integrating these cues may be greatest for negative emotions. The present research investigated age differences in the extent to which gaze direction influenced explicit perception (e.g., anger, fear and joy; Study 1) and social judgments (e.g., of approachability; Study 2) of emotion faces. Gaze direction did not influence the perception of fear in either age group. In both studies, age differences were found in the extent to which gaze direction influenced judgments of angry and joyful faces, with older adults showing less integration of gaze and emotion cues than younger adults. Age differences were greatest when interpreting angry expressions. Implications of these findings for older adults' social functioning are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experience increases the prepulse inhibition of the acoustic startle response in mice.

The authors have previously shown that inhibition of the acoustic startle response by a prepulse increases when it is repetitively elicited over days. The present experiments show in C3H and C57 mice that this change is caused by an increase in prepulse inhibition (PPI) and not by a decrease in prepulse facilitation. This PPI increase is only evoked if prepulses and startle stimuli are repeatedly given in a temporally paired ("contingent") order, proposing an associative learning process. (Only in C57 mice, PPI was additionally increased by adaptation in the same, but not in a different, context). As an underlying mechanism for this PPI increase by experience, the authors hypothesize Hebbian plasticity of an inhibitory synapse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Medial dorsal thalamic lesions impair blocking and latent inhibition of the conditioned eyeblink response in rats.

The effects of lesions of the medial dorsal thalamic nucleus (MD) on blocking and latent inhibition (LI) of the rat eyeblink response were examined in the present study. Previous work has demonstrated that the cingulate cortex and related thalamic areas are involved in processing conditioning stimuli throughout training. The experiments in the present study tested the hypothesis that disruption of cingulothalamic stimulus processing produced by lesions of the MD would impair 2 types of associative learning that involve decremental changes in attention. In Experiment 1, MD lesions severely impaired blocking. In Experiment 2, NM lesions severely impaired LT. The results indicate that lesions of the NM impair incremental, decremental, or both types of changes in stimulus processing during learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Getting the message across: Age differences in the positive and negative framing of health care messages.

Although valenced health care messages influence impressions, memory, and behavior (Levin, Schneider, & Gaeth, 1998) and the processing of valenced information changes with age (Carstensen & Mikels, 2005), these 2 lines of research have thus far been disconnected. This study examined impressions of, and memory for, positively and negatively framed health care messages that were presented in pamphlets to 25 older adults and 24 younger adults. Older adults relative to younger adults rated positive pamphlets more informative than negative pamphlets and remembered a higher proportion of positive to negative messages. However, older adults misremembered negative messages to be positive. These findings demonstrate the age-related positivity effect in health care messages with promise as to the persuasive nature and lingering effects of positive messages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Centrally administered corticotropin-releasing hormone and peripheral injections of strychnine hydrochloride potentiate the acoustic startle response in preweanling rats.

Attempts to condition fear potentiation of startle (FPS) in rats younger than 23 days of age have not been successful, regardless of the type of aversively conditioned stimulus used (P. S. Hunt, R. Richardson, & B. A. Campbell, 1994; R. Richardson, G. Paxinos, & J. Lee, 2000; R. Richardson & A. Vishney, 2000). In the present study, the authors report that peripheral injections of strychnine hydrochloride, a glycine receptor antagonist, and intracerebroventricular infusions of corticotropin releasing hormone (CRH) both potentiated the acoustic startle response (ASR) in 16–18-day-old rats. Because strychnine and CRH have distinct sites of activation in the primary startle pathway, it can be concluded that this pathway is functional and modifiable in rats younger than 23 days of age. This finding suggests that the failure to observe conditioned FPS in preweanling rats is due to an immaturity of the secondary fear circuit responsible for enhancing the ASR during a fear state. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bilateral nature of the conditioned eyeblink response in the rabbit: Behavioral characteristics and potential mechanisms.

In Pavlovian eyeblink conditioning, the conditioned response (CR) is highly lateralized to the eye to which the unconditioned stimulus (US) has been directed. However, the initial conditioning of one eye can facilitate subsequent conditioning of the other eye, a phenomenon known as the intereye transfer (IET) effect. Because a conditioned emotional response (CER), as well as the eyeblink CR, is acquired during eyeblink conditioning and influences the development of the CR, the CER acquired in initial training can plausibly account for the IET effect. To evaluate this possibility, the present study utilized previously determined eyeblink conditioning procedures that effectively decouple the degree of CER and CR development to investigate the IET effect. In each of 3 experiments rabbits were initially trained with comparison procedures that differentially favored the development of the eyeblink CR or the CER, prior to a shift of the US to the alternate eye. The observed differences in the IET suggest that the effect depends largely on the specific development of eyeblink CRs rather than the CER. The neurobiological implications of this apparent bilaterality of the eyeblink CR are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The expression of fear-potentiated startle during development: Integration of learning and response systems.

Relative to freezing, fear-potentiated startle (FPS) is developmentally delayed. Rats trained on Postnatal Day (PD) 18 expressed conditioned stimulus learning on PD 19 in freezing but not in FPS, whereas rats trained on PD 24 and tested on PD 25 expressed both freezing and FPS (Experiment 1). According to a neural maturation hypothesis, this delay results from functional immaturity of pathways mediating FPS. When rats were trained on PD 18, neither delaying the FPS test, allowing FPS pathways to develop, nor administrating the "reminder" treatment, the expression of FPS was promoted (Experiments 1, 2, and 2A). PD 18 learning was expressed in FPS on PD 25 when nontarget conditioned stimulus-unconditioned stimulus training occurred prior to the test, and this effect was modality dependent (Experiments 3 and 4). The authors conclude that engaging mechanisms of associative encoding when FPS pathways are functional is a critical condition for integrating learning and FPS response systems in development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emotional Response in Patients With Frontal Brain Damage: Effects of Affective Valence and Information Content.

The authors investigated the role of the frontal lobes in the emotional response in 19 patients with brain damage and 23 control subjects. They studied the modulation of the startle blink reflex by affective pictures, and other autonomic responses. Patients showed a dissociation between the startle reflex and the affective valence ratings of the pictures, as a result of a low inhibition of the startle reflex by pleasant pictures. Pictures elicited lower skin conductance responses (SCRs) in patients than in controls, whereas the groups did not differ in the SCRs prompted by less significant acoustic stimuli. The findings point to the frontal lobe as a structure involved in the emotional response and in the physiological emotional arousal related to the complexity of the stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)