Diane L. Filion

The psychological significance of human startle eyeblink modification: a review.

The human startle eyeblink reflex is reliably modified by both cognitive and emotional processes. This review provides a comprehensive survey of the current literature on human startle modification and its psychological significance. Issues raised for short lead interval startle inhibition include its interpretation as a measure of protection of processing, sensorimotor gating and early attentional processing. For long lead interval effects, interpretations related to attentional and emotional processing are discussed. Also reviewed are clinical applications to information processing dysfunctions in the schizophrenia spectrum disorders, and to emotional processing disorders. Finally, an integrative summary that incorporates most of the cognitive findings is presented and directions for future research are identified regarding both cognitive and emotional modification of startle.

Modification of the acoustic startle-reflex eyeblink: A tool for investigating early and late attentional processes

The present experiment examined the sensitivity of short and long lead interval startle eyeblink modification to attentional processing. Eighteen college student subjects were presented with a series of intermixed high and low pitched tones and instructed to attend to tones of one pitch and to ignore tones of the other pitch. The majority of the attended and ignored tones served as prepulses for an eyeblink-eliciting burst of white noise presented at lead intervals of 60, 120, 240 and 2000 ms following prepulse onset. Results indicate that both attended and ignored prepulses produce significant startle eyeblink modification: significant blink inhibition at the 60, 120 and 240 ms short lead intervals, and blink facilitation at the 2000 ms long lead interval. In addition, compared with the ignored prepulse, the attended prepulse produced significantly greater blink inhibition at the 120 ms lead interval as well as significantly greater blink facilitation at the 2000 ms lead interval. These results suggest that both short and long lead interval startle eyeblink modification measures may be useful tools for future investigations of the early and later stages of attentional processing.

Attention and schizophrenia: Impaired modulation of the startle reflex.

The startle reflex (SR) elicited by abrupt stimuli can be modified by attention to nonstartling stimuli that shortly precede the startle-eliciting stimulus. The present study of 15 recent-onset, relatively asymptomatic schizophrenic outpatients and 14 demographically matched normal control subjects demonstrated that attentional modulation of SR is impaired in schizophrenic patients. Specifically, the control group exhibited greater startle eye-blink modification following to-be-attended prestimuli than following to-be-ignored prestimuli, whereas the patients failed to show the attentional modulation effect. These results suggest traitlike attentional deficits in schizophrenia because the patients were relatively asymptomatic. The measurement of attentional modulation of SR may provide a nonverbal, reflexive, state-independent marker of the vulnerability to schizophrenia.

Aging, selective attention, and inhibitory processes: a psychophysiological approach.

The present study investigated the efficiency with which younger and older adults allocate attention to relevant and irrelevant stimuli. The model of attention guiding this research links the orienting response with the allocation of attention and habituation with the inhibition of the allocation of attention. We adapted a paradigm developed by Iacono and Lykken (1983) in which subjects are instructed unambiguously either to attend to or to ignore a series of innocuous tones, and the skin conductance orienting response elicited by each tone is measured. Results revealed that young subjects instructed to ignore the tones habituated more quickly than did those instructed to attend to the tones. However, older adults exhibited nondifferential orienting across the 2 instruction conditions. These results suggest an age-related deficit in the ability to inhibit attention to irrelevant stimuli.

11 – Inhibitory processes in cognition and aging

Publisher Summary This chapter reviews a number of studies that have implications for the inhibitory decline hypothesis. Available data suggest that at several levels of information processing in the nervous system, older adults show evidence of a deficit in inhibitory function. Although the evidence is not unequivocal, the following generalization can be made: older adults are less selective information processors than are younger adults. In a variety of situations ranging from elicitation of a brain-stem reflex to the execution of higher language functions, in which both relevant and irrelevant information are available for processing, older adults are more likely to process both classes of information, rather than restricting processing to the most relevant information. The theoretical notion of an inhibitory deficit has been applied with some success in accounting for empirical observations, both in direct tests with models that specifically invoke inhibitory function and less direct tests with tasks for which inhibitory processes are assumed to be relevant.

On the clinical and cognitive meaning of impaired sensorimotor gating in schizophrenia.

Schizophrenia patients have been shown to have a defective sensorimotor gating process as indexed by impaired prepulse inhibition of the startle eyeblink reflex. Moreover, we have previously reported that schizophrenia patients have dysfunctional attentional modulation of prepulse inhibition. The present experiment combined our previous sample of 14 schizophrenia outpatients and 12 demographically matched control subjects with a new sample of 10 outpatients and 6 control subjects. All participants performed a tone-length judgement task that involved attending to one pitch of tone (the attended prepulse) and ignoring another pitch of tone (the ignored prepulse). During this task the acoustic startle eyeblink reflex was electromyographically recorded from the orbicularis oculi muscle. The results replicated the finding of impaired attentional modulation of prepulse inhibition in the new sample of schizophrenia outpatients compared to demographically matched control subjects. Specifically, the new control group exhibited greater startle modification during the attended prepulse, whereas the new patient group failed to show this differential effect. In addition, impaired prepulse inhibition following the attended prepulse was significantly correlated with heightened delusions, conceptual disorganization, and suspiciousness as measured with the expanded Brief Psychiatric Rating Scale. These correlations were significant with prepulse inhibition to the attended prepulse but not with prepulse inhibition to the ignored prepulse. Impaired prepulse inhibition was not correlated with negative symptoms. All in all, the results support the hypothesis that impaired attentional modulation of startle prepulse inhibition reflects basic neurocognitive processes related to thought disorder in schizophrenia.

Sensory processing in schizophrenia: missing and avoiding information

The possible coexistence of supersensitivity and overinhibition (Schizophrenia: Origins, Processes, Treatment and Outcome (1993) 335-350) in schizophrenia was studied using the Adult Sensory Profile as a measure of Dunns (Infants Young Children 9 (1997) 23-25) model of sensory processing. The quadrant model describes sensory sensitivity, sensation avoiding, low registration and sensation seeking as behavioral responses to sensation. Individuals with schizophrenia (N = 27), bipolar disorder (N = 30) and mentally healthy controls (N = 29) were compared using the Adult Sensory Profile. When compared to the mentally healthy group, the results indicated that both the schizophrenia group and the bipolar disorder group had higher scores on sensation avoiding. The schizophrenia group also had higher scores on low registration and lower scores on sensation seeking than the mentally health group. There were no differences between the schizophrenia and bipolar disorder group. According to the findings of this study, individuals with schizophrenia tend to miss available sensory stimuli. When stimuli are indeed detected, they are often avoided.

Selective and nonselective attention effects on prepulse inhibition of startle: a comparison of task and no-task protocols.

The effects of selective and nonselective attentional processes on prepulse inhibition (PPI) of the acoustic startle response were examined by assessing PPI under intermixed task and no-task conditions. Results for the task condition revealed that greater PPI was produced by an attended than an ignored prepulse at a lead interval of 120 ms (marginally significant in the early trial block and significant in the late trial block), indicating an effect of selective attention at this lead interval. Comparisons between the task and no-task conditions revealed significantly greater PPI in the task than no-task condition at a 60-ms lead interval, during early and late trial blocks, indicating a nonselective attention effect at this lead interval. Overall, these results suggest that PPI is sensitive to selective and nonselective attentional influences and indicate that task and no-task PPI protocols reveal unique aspects of sensorimotor gating ability.

Autonomic orienting and the allocation of processing resources in schizophrenia patients and putatively at-risk individuals.

The differential allocation of attentional resources to attended and ignored stimuli was examined by measuring skin conductance orienting responses and secondary reaction time in relatively asymptomatic schizophrenia outpatients, demographically matched normal controls, college students putatively at risk for psychosis, and a college student control group. At-risk participants were those with extreme scores on scales for either anhedonia or perceptual aberration-magical ideation (per-mags). Compared to control groups, the patients and per-mags showed secondary reaction time results suggesting a delay in the differential allocation of attentional resources. This deficit was observed particularly in patients and matched controls with few or no skin conductance orienting responses, suggesting that impaired autonomic orienting is related to underlying cognitive-attentional vulnerability factors.

The time course of face processing: Startle eyeblink response modulation by face gender and expression

The purpose of this study was to investigate the effects of both facial expression and face gender on startle eyeblink response patterns at varying lead intervals (300, 800, and 3500ms) indicative of attentional and emotional processes. We aimed to determine whether responses to affective faces map onto the Defense Cascade Model (Lang et al., 1997) to better understand the stages of processing during affective face viewing. At 300ms, there was an interaction between face expression and face gender with female happy and neutral faces and male angry faces producing inhibited startle. At 3500ms, there was a trend for facilitated startle during angry compared to neutral faces. These findings suggest that affective expressions are perceived differently in male and female faces, especially at short lead intervals. Future studies investigating face processing should take both face gender and expression into account.