Biomedical subjects

Anne M Schell

Publications and source records attributed to Anne M Schell.

9 recordsLinked to original sources

PubMed2006

Effects of perceptual load on startle reflex modification at a long lead interval.

Inhibition of the startle eyeblink response at long lead intervals has been hypothesized to occur when attention is directed away from the modality of the startle stimulus, particularly if attention is directed to a stimulus of high perceptual load. In a test of this hypothesis, participants performed a delayed-matching-to-sample task. On each trial a pattern of dots (the sample) was followed by a second pattern of dots (the target). The task was to say whether the sample and target patterns matched. Perceptual load was manipulated by varying the number of dots in the sample. Auditory startle stimuli were presented 1200 ms after onset of the samples. A linear increase in startle magnitude was found as the number of dots increased. The results are not consistent with the hypothesis that startle inhibition occurs when the lead and startle stimuli are in different modalities under conditions of high perceptual load.

Acoustic Stimulation↗

PubMed2005

Sensorimotor gating, orienting and social perception in schizophrenia.

Basic neurocognition and social cognition appear to influence the social impairments of persons with schizophrenia. This study examined relationships between two very basic automatic processes (i.e., sensorimotor gating and orienting) and social perception in schizophrenic patients. Thirty outpatients with schizophrenia completed psychophysiological measures of sensorimotor gating (prepulse inhibition, PPI), orienting (prepulse facilitation, PPF), and social perception (the Half Profile of Nonverbal Sensitivity, Half PONS). A median split was used to divide patients into poor and good gaters and poor and good orienters. Analyses revealed that patients with good PPI scored significantly higher on the Half PONS than patients with poor PPI. PPI showed a significant correlation (r=-0.54) with Half PONS performance, indicating that schizophrenia patients who were better able to gate out competing stimuli (i.e., less startle) were also better at detecting relevant social cues. Orienting (PPF) and social perception were not related. This study is the first to our knowledge to demonstrate an association between sensorimotor gating and social perception. The findings are consistent with other studies that have demonstrated relationships between basic neurocognition and social cognition. By showing a link between sensorimotor gating and social perception, this study supports social cognition's potential role as a mediator of the relationship between neurocognition and social functioning in schizophrenia.

Adult↗

PubMed2005

Attention and prepulse inhibition: the effects of task-relevant, irrelevant, and no-task conditions.

We investigated whether attentional modulation of prepulse inhibition (PPI) is due to increased protection of processing of attended lead stimuli, decreased protection of processing of ignored lead stimuli, or a combination of both processes. Task and no-task trials, pre-cued by red and blue dots on a computer screen, were randomly intermixed. College student participants were instructed to do a tone duration judgment task on trials preceded by one color (task condition) and to do nothing on trials preceded by the other color (no-task condition). On task condition trials participants were instructed to count the number of longer duration tones of a particular pitch (attended condition) and to ignore tones of a different pitch (ignored condition). White noise startle stimuli were presented at 60 ms and 120 ms lead intervals on some trials in each condition. Additional startle stimuli were presented during the inter-trial intervals to measure baseline (unmodified) startle response. PPI in the attended condition was reliably greater than that in both the ignored and no-task conditions. PPI did not differ between the ignored and no-task conditions. The results are consistent with the conclusion that attentional modulation of PPI is due to increased protection of attended stimuli and not to decreased protection of ignored stimuli. Possible reasons for robust attentional modulation at the 60 ms lead interval as well as the usual 120 ms lead interval are discussed.

Acoustic Stimulation↗

PubMed2005

Effects of perceptual processing demands on startle eyeblink modification.

Startle eyeblink modification was measured during a continuous performance test (CPT) with either clearly focused stimuli or visually degraded stimuli to measure the effects of early perceptual processing demands on startle modification. A startling noise was presented either 120, 240, or 1200 ms following target and nontarget CPT stimuli. In the degraded stimulus CPT, startle inhibition at 240 ms was greater following targets than nontargets and was as great during targets at 240 ms as at 120 ms, whereas in the clearly focused CPT, inhibition declined significantly from 120 to 240 ms. The results indicate that maximum prepulse inhibition is extended in time when the task involves discrimination of degraded visual stimuli and when early perceptual processing demands are high. At 1200 ms, targets and nontargets produced nondifferential inhibition during both CPTs, suggesting that modality-specific attention occurred equally for the two tasks.

Adult↗

PubMed2005

Electrodermal predictors of functional outcome and negative symptoms in schizophrenia.

The ability of electrodermal variables to predict negative symptoms and functional outcome over a 1-year period in schizophrenia was investigated in 78 young, recent-onset outpatients. Patients were stabilized on standardized medication and largely free of psychotic symptoms. Higher levels of both tonic (skin conductance level, nonspecific skin conductance response rate) and phasic (number of skin conductance orienting responses) activity were associated with more negative symptoms and with a combination of poorer social and occupational outcome at 1-year follow-up. This pattern was seen in both male and female patients, and in older and younger patients. Results are interpreted as suggesting that high levels of arousal and overreactivity to the environment may interfere with efficient cognitive processing in schizophrenia, contributing to poor outcome, and that negative symptoms might partially serve as a means of coping with overarousal.

Adult↗

PubMed2004

Prepulse facilitation and prepulse inhibition in schizophrenia patients and their unaffected siblings.

BACKGROUND: Deficits in schizophrenia patients and their first-degree relatives have been reported in prepulse inhibition (PPI), a phenomenon that measures an early stage of information processing (sensorimotor gating). It is less clear whether these information processing deficits extend to prepulse facilitation (PPF), which measures a later stage of generalized alerting or orienting. METHODS: This study examined three separate issues: first, whether schizophrenia patients have deficits in PPI and PPF; second, whether the siblings of patients show deficits in these processes; and third, whether prepulse duration influences the degree of the deficits. These issues were examined in 76 schizophrenia patients, 36 of their siblings, and 41 normal control subjects. RESULTS: Patients and siblings did not differ from control subjects in PPI, perhaps due to the use of different procedural parameters compared with other laboratories that have consistently found PPI deficits in schizophrenia patients. Patients and their siblings produced significantly less PPF than control subjects. For both PPI and PPF, prepulse duration was not a significant factor. CONCLUSIONS: These results imply that PPF deficits reveal a generalized alerting or orienting deficit that is present in both schizophrenia patients and their siblings, suggesting that this deficit may be tapping an endophenotypic vulnerability factor.

Acoustic Stimulation↗

PubMed2004

The functional relationship between visual backward masking and prepulse inhibition.

This experiment demonstrated a relationship between prepulse inhibition (PPI) of the startle eyeblink and visual backward masking in college students. It was hypothesized that recovery from backward masking effects is due in part to sensory gating, as assessed by auditory and visual PPI. Visual presentations of letters served as targets or visual prepulses in an intermixed session of backward masking and PPI. Backward masking and PPI (both auditory and visual) were assessed at stimulus onset asynchronies of 30, 45, 60, 120, and 150 ms. A repeated-measures regression revealed that there was a relationship between backward masking and PPI for both visual and auditory PPI, with higher levels of PPI being associated with greater recovery from backward masking. The data are consistent with the hypothesis that recovery from backward masking effects is affected by sensory gating acting in part to gate out the interruptive effects of the mask.

Acoustic Stimulation↗

PubMed2002

What does electrodermal activity tell us about prognosis in the schizophrenia spectrum?

Various dysfunctions in electrodermal activity (EDA) have been found in schizophrenic patients. The present paper reviews evidence that the electrodermal dysfunctions may carry prognostic information regarding subsequent symptoms, as well as social and occupational outcome. Although the findings are not entirely consistent, heightened electrodermal activity as indicated by frequent orienting responses to innocuous stimuli, elevated skin conductance level (SCL), and frequent non-specific skin conductance responses (NS-SCR) is most often associated with poor symptomatic, social, and occupational outcome in schizophrenic patients. There have been no studies that have directly examined electrodermal prognostic indicators in schizotypal individuals. However, high-risk studies suggest that heightened electrodermal activity may be prognostic of poor outcome in schizotypals as well. Thus, abnormally high electrodermal arousal and reactivity is predictive of poor outcome in at least some patients. The theoretical implications of these findings and directions for further research are briefly discussed.

Arousal↗

PubMed2002

The temporal stability of electrodermal variables over a one-year period in patients with recent-onset schizophrenia and in normal subjects.

Test-retest stability of electrodermal (EDA) variables indexing both general autonomic arousal (e.g., skin conductance level, number of nonspecific skin conductance responses) and attention to external stimuli (e.g., number of skin conductance orienting responses, electrodermal responder/nonresponder status) was assessed in 71 young, recent-onset schizophrenia patients and 36 demographically matched normal subjects. Significant stability over a 1-year period was found for both patients and normal subjects for most EDA variables and for responder/nonresponder status, with test-retest correlations generally being higher for normal subjects. The lower reliability for patients was not attributable to symptomatic fluctuations during the follow-up period and may reflect poorer arousal regulation among the patients. Among measures of responding to nontask stimuli, a simple count of the number of orienting responses occurring was more stable than was a traditional trials-to-habituation measure.

Adult↗