Startle Eyeblink Reflex Research Articles

α2-NORADRENERGIC EFFECTS ON HABITUATION AND PREPULSE INHIBITION OF THE HUMAN STARTLE REFLEX

Affective modulation of the eyeblink startle reflex, by unpleasant slides, was found to be limited to subjects high on Harm Avoidance (HA; Cloninger, 1986); low HA subjects did not respond to unpleasant slides with potentiated startle reflexes. This result provides a replication of Corr, Wilson, Fotiadou, Kumari, Gray, Checkley and Gray (1995a), and supports the hypothesis that individual differences in trait anxiety are important in affective modulation of the startle reflex. It is concluded that Cloninger's HA should be routinely included in future startle modulation experiments.

Frontal–striatal–thalamic mediodorsal nucleus dysfunction in schizophrenia-spectrum patients during sensorimotor gating

Prepulse inhibition (PPI) refers to a reduction in the amplitude of the startle eyeblink reflex to a strong sensory stimulus, the pulse, when it is preceded shortly by a weak stimulus, the prepulse. PPI is a measure of sensorimotor gating which serves to prevent the interruption of early attentional processing and it is impaired in schizophrenia-spectrum patients. In healthy individuals, PPI is more robust when attending to than ignoring a prepulse. Animal and human work demonstrates that frontal–striatal–thalamic (FST) circuitry modulates PPI. This study used functional magnetic resonance imaging (fMRI) to investigate FST circuitry during an attention-to-prepulse paradigm in 26 unmedicated schizophrenia-spectrum patients (13 schizotypal personality disorder (SPD), 13 schizophrenia) and 13 healthy controls. During 3T-fMRI acquisition and separately measured psychophysiological assessment of PPI, participants heard an intermixed series of high- and low-pitched tones serving as prepulses to an acoustic-startle stimulus. Event-related BOLD response amplitude curves in FST regions traced on co-registered anatomical MRI were examined. Controls showed greater activation during attended than ignored PPI conditions in all FST regions—dorsolateral prefrontal cortex (Brodmann areas 46, 9), striatum (caudate, putamen), and the thalamic mediodorsal nucleus. In contrast, schizophrenia patients failed to show differential BOLD responses in FST circuitry during attended and ignored prepulses, whereas SPD patients showed greater-than-normal activation during ignored prepulses. Among the three diagnostic groups, lower left caudate BOLD activation during the attended PPI condition was associated with more deficient sensorimotor gating as measured by PPI. Schizophrenia-spectrum patients exhibit inefficient utilization of FST circuitry during attentional modulation of PPI. Schizophrenia patients have reduced recruitment of FST circuitry during task-relevant stimuli, whereas SPD patients allocate excessive resources during task-irrelevant stimuli. Dysfunctional FST activation, particularly in the caudate may underlie PPI abnormalities in schizophrenia-spectrum patients.

The effects of nicotine on the attentional modification of the acoustic startle response in nonsmokers

Research on nicotine and attention has mainly utilized samples of deprived smokers and tasks requiring volitional responses, raising the question of whether nicotine improves attention or simply alleviates withdrawal or improves motor speed. This study used the startle eyeblink reflex to assess nicotine effects on auditory attention in nonsmokers. Sixty-seven healthy young adult nonsmokers completed a tone discrimination task. Acoustic startle probes were presented 60, 120, 240, or 4,500 ms after the onset of two-thirds of the tones and during intertrial intervals. Attention was assessed via (1) short-lead prepulse inhibition (PPI) of startle, a measure of early filtering; (2) long-lead prepulse facilitation (PPF) of startle, a measure of sustained processing; and (3) the modification of PPI and PPF by focused attention. Participants completed two laboratory sessions, once while wearing a 7-mg transdermal nicotine patch and once while wearing a placebo patch. Patches were administered in a double-blind procedure. Nicotine increased overall PPI, eta2(p)=0.09. Attention increased long-lead PPF, eta2(p)=0.25, but not short-lead PPI. Nicotine did not reliably enhance early or late controlled attentional processing in the sample overall. However, correlational analyses demonstrated that nicotine most improved attentional modification of short-lead PPI among participants with the weakest early attentional processing under placebo conditions. Nicotine enhanced early attentional filtering in general, and the effects of nicotine on early focused attention were dependent upon individual differences in placebo levels of attentional processing. The present data suggest that the effects of nicotine on attention extend beyond the alleviation of withdrawal and simple motor speeding.

Primary and secondary neural networks of auditory prepulse inhibition: a functional magnetic resonance imaging study of sensorimotor gating of the human acoustic startle response

Feedforward inhibition deficits have been consistently demonstrated in a range of neuropsychiatric conditions using prepulse inhibition (PPI) of the acoustic startle eye-blink reflex when assessing sensorimotor gating. While PPI can be recorded in acutely decerebrated rats, behavioural, pharmacological and psychophysiological studies suggest the involvement of a complex neural network extending from brainstem nuclei to higher order cortical areas. The current functional magnetic resonance imaging study investigated the neural network underlying PPI and its association with electromyographically (EMG) recorded PPI of the acoustic startle eye-blink reflex in 16 healthy volunteers. A sparse imaging design was employed to model signal changes in blood oxygenation level-dependent (BOLD) responses to acoustic startle probes that were preceded by a prepulse at 120 ms or 480 ms stimulus onset asynchrony or without prepulse. Sensorimotor gating was EMG confirmed for the 120-ms prepulse condition, while startle responses in the 480-ms prepulse condition did not differ from startle alone. Multiple regression analysis of BOLD contrasts identified activation in pons, thalamus, caudate nuclei, left angular gyrus and bilaterally in anterior cingulate, associated with EMG-recorded sensorimotor gating. Planned contrasts confirmed increased pons activation for startle alone vs 120-ms prepulse condition, while increased anterior superior frontal gyrus activation was confirmed for the reverse contrast. Our findings are consistent with a primary pontine circuitry of sensorimotor gating that interconnects with inferior parietal, superior temporal, frontal and prefrontal cortices via thalamus and striatum. PPI processes in the prefrontal, frontal and superior temporal cortex were functionally distinct from sensorimotor gating.

Startle reflex modulation and autonomic responding during anxious apprehension in panic disorder patients

The present study explored anxious apprehension in panic disorder patients and controls in two threat conditions, darkness and threat of shock. Autonomic arousal and startle eyeblink reflexes were recorded in 26 panic disorder patients and 22 controls during adaptation, a safe condition, threat of shock, and darkness. Exposure to darkness resulted in a clear potentiation of the startle reflex. Panic patients but not controls responded with an increase in heart rate that was positively related to severity of agoraphobic avoidance. Threat of shock resulted in a startle potentiation that tended to be stronger in panic patients without comorbid depression than controls and attenuated in those patients who suffered from severe depression. These data suggest that only panic patients without depression belong to the fear disorders spectrum whereas panic patients with comorbid depression might rather belong to the distress disorders profile.

Does emotion modulate the blink reflex in human conditioning? Startle potentiation during pleasant and unpleasant cues in the picture–picture paradigm

Emotional processes modulate the size of the eyeblink startle reflex in a picture-viewing paradigm, but it is unclear whether emotional processes are responsible for blink modulation in human conditioning. Experiment 1 involved an aversive differential conditioning phase followed by an extinction phase in which acoustic startle probes were presented during CS+, CS-, and intertrial intervals. Valence ratings and affective priming showed the CS+ was unpleasant postacquisition. Blink startle magnitude was larger during CS+ than during CS-. Experiment 2 used the same design in two groups trained with pleasant or unpleasant pictorial USs. Ratings and affective priming indicated that the CS+ had become pleasant or unpleasant in the respective group. Regardless of CS valence, blink startle was larger during CS+ than CS- in both groups. Thus, startle was not modulated by CS valence.

Abnormal affective startle modulation in individuals with psychogenical movement disorder

Despite recent advances, psychogenic movement disorder (PMD) remains a poorly understood phenomenon. Emotional functioning and responsiveness to stress are believed to play a role in the development of psychogenic symptoms, but empirical studies examining emotional responsiveness in PMD and other conversion disorders are lacking. We investigated modulation of the startle eyeblink reflex by affective pictures in 12 patients with PMD and 12 age- and education-matched control participants. Participants viewed positive, neutral, and negative pictures, while eyeblink responses to white noise bursts were recorded. Control participants showed the expected pattern of startle modulation, with significant potentiation by negative pictures and slight (nonsignificant) inhibition by positive pictures. In the PMD group, however, both positive and negative pictures yielded significantly greater startle responses than neutral pictures. Depression and anxiety symptomatology did not correlate with startle modulation, and the two groups did not differ in self-reported emotional reactions to the pictures. Our findings suggest that individuals with PMD show aversive physiological reactions to positive as well as negative stimuli. Abnormal affective startle modulation may be used to help distinguish between malingering and PMD. Future studies using larger samples are needed to better understand the role of emotions in conversion disorder.

Deficient attentional modulation of startle eyeblink is associated with symptom severity in the schizophrenia spectrum

Patients with schizophrenia-spectrum disorders show deficient prepulse inhibition (PPI) of the startle eyeblink reflex which is thought to reflect an early stage of information processing called automatic sensorimotor gating. They also exhibit deficient attentional modulation of PPI and prepulse facilitation (PPF) of startle which is thought to reflect deficient early and later controlled attentional processing. This is the first study to assess attentional modulation of PPI and PPF in a 3-group schizophrenia-spectrum sample of age- and sex-matched unmedicated schizotypal personality disorder (SPD) and schizophrenia patients, and healthy controls. Participants performed a tone-length judgment task involving attended, ignored, and novel tone prepulses while the acoustic startle eyeblink reflex was measured. Healthy controls showed greater PPI and PPF during the attended prepulses compared with the ignored prepulses. In contrast, both the SPD and schizophrenia patient groups failed to show this pattern, indicating deficient early and later controlled attentional processing. These findings suggest abnormal attentional modulation of PPI and PPF may be a trait-like feature found in patients with schizophrenia-spectrum disorders. Among the schizophrenia-spectrum sample, more deficient PPI during the attended prepulses was associated with greater symptom severity as measured by the total 18-item Brief Psychiatric Rating Scale score.

Examining the Eyeblink Startle Reflex as a Measure of Emotion and Motivation to Television Programming

This study examines the reliability and validity of the eyeblink startle reflex as a measure of emotional and motivational responding to television content. A pretest uses continuous response measurement to identify pleasant, neutral, and unpleasant scenes from a television drama. Acoustic startle probe methodology and facial electromyography are used to measure responding to these scenes during an experiment. Although past research has suggested that the startle reflex is a reliable measure of emotional responding to television and film content, there is reason to expect that this effect may be obfuscated if the probe falls close to a camera change or scene change. The startle reflex data offer convergent validity with the continuous response data and concurrent validity with the facial electromyographic data. However, the presence of a camera change or scene change within 500 ms of the startle probe did disrupt the emotional modulation of the reflex. These data show that the startle reflex can be a valid and reliable temporally precise measure of emotional responding to television programming if proximity to scene changes and camera changes is controlled.

Impaired classical eyeblink conditioning in elderly human subjects: the role of unconditioned response magnitude

Classical conditioning is impaired in elderly subjects, and an experiment investigated the role of unconditioned response magnitude and autonomic arousal in this aging-related impairment. Two groups of young (n = 20, mean age 23.8 years) and elderly (n = 21, mean age 73.8 years) healthy subjects participated in the experiment. Single-cue classical eyeblink conditioning was in effect for 72 trials, with a tone as the conditioned stimulus (CS) and an airpuff to the eye as the unconditioned stimulus (US). The CS was presented alone in eight additional trials to allow recordings of skin conductance and heart rate responses. Startle eyeblink reflexes were elicited either alone or in the presence of the CS after the end of the conditioning procedure to investigate startle potentiation. More young (95%) than elderly (76%) subjects identified the CS - US contingency in a post-conditioning questionnaire, whereas only 38% of the elderly and 85% of the young subjects acquired the conditioned response (CR). Unconditioned blink reflex magnitudes were greater in the subjects who had acquired the CR. Heart rate deceleration was seen in both young and elderly subjects who had acquired the conditioned response. Startle reflexes and skin conductance responses were related to conditioning in young but not in elderly subjects. Unconditioned response magnitude was the best predictor for the acquisition of the CR. Together with the questionnaire data, this indicates that peripheral factors play a significant role in the impairment of classical eyeblink conditioning in elderly people. Autonomic arousal was not related to acquisition of the CR in elderly subjects.

Affect-modulated startle in adults with childhood-onset depression: Relations to bipolar course and number of lifetime depressive episodes

To study affect regulation in adults with unipolar ( n=38) and bipolar ( n=38) forms of childhood-onset depression (COD), as compared with adults with no history of psychiatric illness ( n=60), we examined affective modulation of the startle eyeblink reflex. Participants were subjected to binaural bursts of white noise while viewing pictures designed to elicit pleasant, neutral, or unpleasant affective states. The blink response was recorded from surface electrodes over the orbicularis oculi muscle during and following pictures. Participants rated the valence and arousal of their responses. Unlike control or bipolar groups, the unipolar group displayed a greater startle during the neutral condition than during the pleasant condition, and failed to display an increase in startle during the unpleasant condition. The bipolar group, unlike the unipolar and control groups, displayed a similar startle response after pleasant and unpleasant pictures. Participants with a high number of lifetime depressive episodes displayed a blunted startle response across affective conditions. Groups reported similar subjective responses to affective stimuli. Current affective symptoms and comorbid diagnoses did not influence startle modulation. In unipolar and bipolar forms of COD, unusual affective modulation or maintenance of the startle response, respectively, may reflect underlying deficits in affect regulation.

Electromyographic indices of neuromuscular reflexes

Herein, we describe the use of two neuromuscular reflexes, the acoustic startle eye blink reflex and the Hoffmann (H‐) reflex, in the context of exercise neuroscience. The reflex probe paradigm has advantages for use in the field of exercise neuroscience and can be obtained without distraction during the performance of an experimental task. The startle eye blink reflex, measured from the orbicularis oculi muscles, is modulated by the affective foreground context and reflects the relative activation of the appetitive and defensive motivational systems of the brain. The H‐reflex, measured most often from the soleus muscle, reflects the efficacy of synaptic transmission between the la afferent fiber and alpha motoneuron. Changes in the amplitude of the startle eye blink reflex and H‐reflex after exercise have been observed; however, the meaning of the changes is not clear. Further research using these indices among those diagnosed with an affective disorder, or among individuals with multiple sclerosis or spinal cord injuries, will greatly enhance our understanding of the effects of physical activity on the central nervous system

Emotional Responses to Pictures of Oneself in Healthy College Age Females

Emotional responses related to self-perceptions were investigated in healthy college-aged females using a picture-viewing paradigm that consisted of four categories of pictures (pleasant, neutral, unpleasant, and full body pictures of themselves). The startle eye-blink reflex, facial EMG, and self-reported valence, arousal, and dominance measures were recorded for each picture. Startle reflex and facial EMG measures exhibited decreased activation for self-pictures compared to the other affective categories. Self-reports indicated self-pictures were rated as moderately pleasant, low arousing, and moderately dominant relative to the other affective picture categories. The findings of reduced startle blink reflex coupled with decreased activation for all facial EMG measures and the moderate self-report ratings suggest increased attentional processing for self-pictures. These findings provide an understanding of emotional responses to self-perceptions in healthy young females.

Motivated Engagement to Appetitive and Aversive Fanship Cues: Psychophysiological Responses of Rival Sport Fans

Psychophysiological responses of two rival sport fan groups were assessed within the context of Lang’s biphasic theory of emotion. Twenty-four participants, placed in two groups based on their identification with local sport teams, viewed 6 pictures from 6 categories: team-relevant pleasant sport, team-irrelevant sport, team-relevant unpleasant sport, erotica, household objects, and mutilation. Fans rated appetitive sport pictures higher in pleasure and arousal compared to aversive sport pictures. Physiological measures (startle probe-P3, the startle eye-blink reflex, slow cortical potentials to picture onset, and skin conductance) differentiated both appetitive and aversive team-relevant categories from team-irrelevant pictures, and increased orbicularis oculi EMG was found only for team-relevant appetitive pictures. These results suggest there are differences between rival sport fans in response to the same pictorial stimuli, and further suggest that fans provide an ideal population in which to measure motivation toward appetitive stimuli.

Pre-pulse inhibition of the acoustic startle eye-blink in the Göttingen minipig

Pre-pulse inhibition (PPI) of the startle response is a measure of sensorimotor gating which has been frequently shown to be deficient in schizophrenic patients. In humans it is typically measured as the attenuation of the startle eye-blink reflex EMG when a startle eliciting noise is preceded by a weak white noise pre-pulse (PP), the interval between the PP and the startle noise stimulus (SNS) determining the degree of inhibition. Aiming at developing a new animal model of schizophrenia, we have investigated the acoustic startle eye-blink and PPI in 10 Göttingen minipigs. The stimuli and the block design of the stimulation were similar to paradigms used in human research. Initially the startle habituation across trials and blocks, secondarily the PPI at PP to SNS intervals of 30, 60, 120, 220, 520, 1020 and 2020 ms was investigated. One pig out of ten did not have a startle response, and three other pigs did not have a startle response of a sufficient magnitude to demonstrate the PPI seen in the other six pigs at the expected PP intervals of 60, 120, and 220 ms. Maximal inhibition was seen at the 220 ms interval (mean PPI 58.6%, range −18.4 to 94.6%, N=9). Most of the results in the pigs are in accordance with findings in studies of the human startle eye-blink EMG and this initial study promotes further studies and the use of the PPI measure in the validation of minipig models of psychiatric disorders.

Emotion and motivated behavior: postural adjustments to affective picture viewing

Thirty-six participants (18 female, 18 male) viewed affective pictures to investigate the coupling between emotional reactions and motivated behavior. Framed within the biphasic theory of emotion, the three systems approach was employed by collecting measures of subjective report, expressive physiology, and motivated behavior. Postural adjustments associated with viewing affective pictures were measured. Results indicated sex-differences for postural responses to unpleasant pictures; an effect not found for pleasant and neutral picture contents. Females exhibited increased postural movement in the posterior direction, and males exhibited increased movement in the anterior direction, for unpleasant pictures. Subjective report of valence and arousal using the self-assessment manikin (SAM), and the startle eye-blink reflex were collected during a separate session, which replicated previous picture-viewing research. Specifically, participants rated pleasant pictures higher in valence and exhibited smaller startle responses compared to unpleasant pictures. Females also reported lower valence ratings compared to males across all picture contents. These findings extend our knowledge of motivated engagement with affective stimuli and indicate that postural responses may provide insight into sex-related differences in withdrawal behavior.

Genetic influences on prepulse inhibition of startle reflex in humans

Prepulse inhibition (PPI) is a suppression of the startle reflex that occurs when an intense startling stimulus is preceded by a weaker ‘prepulse’ stimulus. PPI deficits have been implicated in the biological bases of schizophrenia and some other neuropsychiatric disorders and proposed as a possible biological marker (endophenotype) for genetic studies. However, little is known about the genetic determination of PPI in humans. We examined acoustic eye-blink startle reflex and PPI in 142 young female twins (40 monozygotic and 31 dizygotic pairs) and conducted a biometrical genetic analysis using structural equation modeling. PPI showed significant heritability suggesting that over 50% of PPI variance in this sample can be attributed to genetic factors. Baseline startle magnitude showed higher heritability (about 70%).

Genetic influences on prepulse inhibition of startle reflex in humans

Prepulse inhibition (PPI) is a suppression of the startle reflex that occurs when an intense startling stimulus is preceded by a weaker ‘prepulse’ stimulus. PPI deficits have been implicated in the biological bases of schizophrenia and some other neuropsychiatric disorders and proposed as a possible biological marker (endophenotype) for genetic studies. However, little is known about the genetic determination of PPI in humans. We examined acoustic eye-blink startle reflex and PPI in 142 young female twins (40 monozygotic and 31 dizygotic pairs) and conducted a biometrical genetic analysis using structural equation modeling. PPI showed significant heritability suggesting that over 50% of PPI variance in this sample can be attributed to genetic factors. Baseline startle magnitude showed higher heritability (about 70%).

Effect of varying levels of mental workload on startle eyeblink modulation

Previous research using punctuate reaction time and counting tasks has found that the startle eyeblink reflex is sensitive to attentional demands. The present experiment explored whether startle eyeblink is also modulated during a complex continuous task and is sensitive to different levels of mental workload. Participants (N = 14) performed a visual horizontal tracking task either alone (single-task condition) or in combination with a visual gauge monitoring task (multiple-task condition) for three minutes. On some task trials, the startle eyeblink reflex was elicited by a noise burst. Results showed that startle eyeblink was attenuated during both tasks and that the attenuation was greater during the multiple-task condition than during the single-task condition. Subjective ratings, endogenous eyeblink rate, heart period, and heart period variability provided convergent validity of the workload manipulations. The findings suggest that the startle eyeblink is sensitive to the workload demands associated with a continuous visual task. The application of startle eyeblink modulation as a workload metric and the possibility that it may be diagnostic of workload demands in different stimulus modalities is discussed.

Effects of caffeine, caffeine-associated stimuli, and caffeine-related information on physiological and psychological arousal

To test the classical conditioning and expectancy theories of placebo effects. Two experiments investigated whether administration of caffeine-associated stimuli elicited conditioned arousal, and whether information that a drink contained or did not contain caffeine modulated arousal. Experiment 1 (n=21) used a 2 Caffeine (0 and 2 mg/kg) x 2 Solution (Coffee, Juice) x 2 Information (Told caffeine, Told not-caffeine) within-subjects design. Experiment 2 (n=48) used a 2 Solution (Coffee, Orange juice) x 3 Information (Told caffeine, Told not-caffeine, No information) between-subjects design. Indexes of arousal were skin conductance responses and levels, startle eyeblink reflexes, cardiovascular measures, and the Bond and Lader 1974 mood scale. Caffeine-associated stimuli increased alertness, contentedness and skin conductance levels, and information that the drink contained caffeine decreased calmness in Experiment 1. However, unexpected information about the caffeine content of the drink, and the order of the conditions, could have masked some effects of the experimental manipulations. Experiment 2 followed up this hypothesis. The results showed a conditioned increase in startle eyeblink reflexes, and that caffeine-associated stimuli together with information that the drink contained caffeine increased contentedness. Caffeine-associated stimuli increased arousal, and information about the content of the drink modulated arousal in the direction indicated by the information. Thus, both the classical conditioning and expectancy theories of placebo effects received support, and placebo effects were strongest when both conditioned responses and expectancy-based responses acted in the same direction.