Tracing Links Between Early Auditory Information Processing and Negative Symptoms in Schizophrenia: An ERP Study

Background: Negative symptoms represent a heterogeneous dimension with a strong impact on functioning of subjects with schizophrenia (SCZ). Five constructs are included in this dimension: anhedonia, asociality, avolition, blunted affect, and alogia. Factor analyses revealed that these symptoms cluster in two domains: experiential domain (avolition, asociality, and anhedonia) and the expressive deficit (alogia and blunted affect), that might be linked to different neurobiological alterations. Few studies investigated associations between N100, an electrophysiological index of early sensory processing, and negative symptoms, reporting controversial results. However, none of these studies investigated electrophysiological correlates of the two negative symptom domains.Objectives: The aim of our study was to evaluate, within the multicenter study of the Italian Network for Research on Psychoses, the relationships between N100 and negative symptom domains in SCZ.Methods: Auditory N100 was analyzed in 114 chronic stabilized SCZ and 63 healthy controls (HCs). Negative symptoms were assessed with the Brief Negative Symptom Scale (BNSS). Repeated measures ANOVA and correlation analyses were performed to evaluate differences between SCZ and HCs and association of N100 features with negative symptoms.Results: Our findings demonstrated a significant N100 amplitude reduction in SCZ compared with HCs. In SCZ, N100 amplitude for standard stimuli was associated with negative symptoms, in particular with the expressive deficit domain. Within the expressive deficit, blunted affect and alogia had the same pattern of correlation with N100.Conclusion: Our findings revealed an association between expressive deficit and N100, suggesting that these negative symptoms might be related to deficits in early auditory processing in SCZ.

Effects of the COMT Val158Met polymorphism on N100 component of auditory evoked potential and oddball task performance in healthy subjects and schizophrenia patients

The study was conducted with the participation of 47 healthy subjects and 48 schizophrenia patients. The different effects of Val158Met polymorphism have been found in the control and patients groups. The increased N100 amplitude and minimal number of the error responses in oddball task were revealed in healthy subjects with Val/Val genotype. In patients group Val/Val genotype was related to the decreased N100 amplitude and worse performance of oddball task.

The Effects of Vigilance and Visual Distraction on the P50 Mid-Latency Auditory Evoked Potential

Sensory gating function has been investigated through measurement of the P50 evoked potential. However, the susceptibility of auditory P50 sensory gating to attentional modulation remains unclear. We sought to investigate the effects of vigilance (sustaining alertness across multiple recording blocks) and visual distraction (watching a muted movie versus a static fixation cross). We specifically chose a movie as the distracting stimulus because investigators sometimes show muted movies during P50 paradigms and the effects of this method were previously unknown. We recorded evoked potentials in a standard paired-click paradigm from groups watching a movie or static fixation cross; both groups completed four identical blocks of recording. Ratings of fatigue were recorded throughout the experiment. P50 and N100 amplitude showed signs of habituation, although N100’s amplitude reduction was more prominent than P50. P50 suppression did not change over the course of the recording session, despite increasing fatigue ratings. P50 suppression was significantly stronger for the participants who watched a movie during the recording. When comparing P50 gating results across studies, care should be taken to consider differing methodologies.

Auditory Event-Related Potentials and Reaction Times in Migraine Children

Cognitive processing was investigated interictally in 18 children with migraine without aura and 18 age-matched controls by measuring event-related potentials (ERPs) and reaction times (RTs) during an acoustic oddball paradigm. Results showed that N100 amplitude evoked by frequent stimuli was significantly smaller in patients compared with controls. Habituation of target P300 amplitude was observed in patients but not in controls. Mean RTs were equivalent in the two groups, but migraine children made more errors than controls.