Nagamoto HT, Adler LE, Waldo MC, Griffith J, Freedman R. Gating of auditory response in schizophrenics and normal controls: effects of recording site and stimulation interval on the P50 wave. Schizophr Res 4: 31-40
Auditory evoked potentials were recorded using a paired stimulus, conditioning-testing paradigm from 14 schizophrenic patients and 13 normal subjects with no family history of psychotic disorder. Previous studies of the vertex P50 wave using this paradigm have demonstrated a possible sensory gating deficit in schizophrenics, as shown by their failure to diminish the response to a test stimulus presented 500 ms after a conditioning stimulus. Recordings were made at Cz, Fz, C3, T3, C4, and T4, to compare effects at different recording sites with this paradigm. Schizophrenics had significantly poorer sensory gating than normals, with the most significant difference between the groups at Cz. In addition to the 500 ms interval, subjects were also recorded at a conditioning-testing interval of 100 ms. Most schizophrenics showed normal sensory gating at the 100 ms interval, despite their abnormalities at 500 ms. The results indicate that Cz is optimal recording site for this paradigm, and that gating abnormalities in schizophrenic subjects are limited to specific interstimulus intervals.
"Finally, the percentage of P50 suppression (P50 supp ) was calculated using the following formula: P50 supp = [1 − (A S2 /A S1 )] × 100, where A S1 and A S2 are the amplitude of the conditioning and testing of the P50 component, respectively (Clementz et al., 1997). Minimums of 100% suppression or 100% facilitation were used to prevent outliers from disproportionately affecting the group means (Cadenhead, Light, Geyer, & Braff, 2000; Nagamoto et al., 1991). "
"Finally, the percentage of P50 suppression (P50 supp ) was calculated using the following formula: P50 supp = [1− (A S2 /A S1 )]×100, where A S1 and A S2 are the amplitude of the conditioning and testing P50 component respectively (Clementz et al., 1997). Minimums of 100% suppression or 100% facilitation were used to prevent outliers from disproportionately affecting the group means (Nagamoto et al., 1991; Cadenhead et al., 2000). "
[Show abstract][Hide abstract] ABSTRACT: Background:
P50 amplitude changes in dual click conditioning-testing procedure might be a neurophysiological marker of deficient sensory gating in schizophrenia. However, the relationship between abnormalities in the neurophysiological and phenomenological dimensions of sensory gating in schizophrenia remains unclear. The aim of the present study was to determine if patients with low P50-suppression (below 50%) report more perceptual anomalies.
Three groups were compared: twenty-nine schizophrenia patients with high P50-suppression (above 50% amplitude suppression), twenty-three schizophrenia patients with low P50-suppression (below 50%) and twenty-six healthy subjects. The Sensory Gating Inventory (SGI), a four-factor self-report questionnaire, was used to measure perceptual anomalies related to sensory gating. A comparison of demographic and clinical data was also carried out.
Patients with low P50-suppression presented: i) significantly higher scores on the SGI (for the overall SGI score and for each of the 4 factors) and ii) significantly larger P50 amplitude at the second click, than both patients with high P50-suppression and healthy subjects. There were no group differences in the most of demographic and clinical data.
The finding offers support for conceptual models wherein abnormal neurophysiologic responses to repetitive stimuli give rise to clinically relevant perceptions of being inundated and overwhelmed by external sensory stimuli. Further studies are needed to explore the contributions of clinical symptoms, medication and neuropsychological functions to the relationship between P50-suppression and the SGI, and the role of sensory "gating in" versus "gating out".
Schizophrenia Research 06/2014; 157(1-3). DOI:10.1016/j.schres.2014.05.013 · 3.92 Impact Factor
"Peaks were 35e86 ms (P50), 79e149 ms (N100), and 54e278 ms (P200). Requirements for S2 included: P50 peaking within 10 ms of P50 S1 (Nagamoto et al., 1991); N100 and P200 within 40 or 80 ms of S1. If no peaks occurred within those windows, the component was considered completely attenuated, unless iso-potential maps showed clear S2-elicited fronto-central components outside the windows. "
[Show abstract][Hide abstract] ABSTRACT: Early responses to stimuli can be measured by sensory evoked potentials (EP) using repeated identical stimuli, S1 and S2. Response to S1 may represent efficient stimulus detection, while suppression of response to S2 may represent inhibition. Early responses to stimuli may be related to impulsivity. We compared EP reflecting stimulus detection and inhibition in bipolar disorder and healthy controls, and investigated relationships to impulsivity. Subjects were 48 healthy controls without family histories of mood disorder and 48 with bipolar disorder. EP were measured as latencies and amplitudes for auditory P50 (pre-attentional), N100 (initial direction of attention) and P200 (initial conscious awareness), using a paired-click paradigm, with identical stimuli 0.5 s apart. Impulsivity was measured by questionnaire and by laboratory tests for inability to suppress responses to stimuli or to delay response for a reward. Analyses used general linear models. S1 amplitudes for P50, N100, and P200, and gating of N100 and P200, were lower in bipolar disorder than in controls. P50 S1 amplitude correlated with accurate laboratory-task responding, and S2 amplitude correlated with impulsive task performance and fast reaction times, in bipolar disorder. N100 and P200 EP did not correlate with impulsivity. These findings were independent of symptoms, treatment, or substance-use history. EPs were not related to questionnaire-measured or reward-based impulsivity. Bipolar I disorder is characterized by reduced pre-attentional and early attentional stimulus registration relative to controls. Within bipolar disorder, rapid-response impulsivity correlates with impaired pre-attentional response suppression. These results imply specific relationships between ERP-measured response inhibition and rapid-response impulsivity.
Journal of Psychiatric Research 09/2013; 47(12). DOI:10.1016/j.jpsychires.2013.08.018 · 3.96 Impact Factor
Note: This list is based on the publications in our database and might not be exhaustive.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.