Elevated midline-parietal gamma band noise power in schizophrenia but not in bipolar patients

Abstract

Gamma oscillations are key in coordinating brain activity and seem to be altered in schizophrenia. In previous work, we studied the spatial distribution of a noise power measure (scalp-recorded electroencephalographic activity unlocked to stimuli) and found higher magnitudes in the gamma band related to symptoms and cognition in schizophrenia. In the current study, we sought to replicate those findings and to study its specificity for schizophrenia in a completely independent sample. A principal component analysis (PCA) was used to determine the factorial structure of gamma noise power acquired with an electroencephalographic recording during an odd-ball P300 paradigm in the 250- to 550-ms window in 70 patients with schizophrenia (16 patients with first episode), 45 bipolar patients and 65 healthy controls. Clinical and cognitive correlates of the resulting factors were also assessed. Three factors arose from the PCA. The first displayed a midline-parietal distribution (roughly corresponding to the default mode network), the second was centro-temporal and the third anterior-frontal. Schizophrenia but not bipolar patients showed higher gamma noise power loadings in the first factor in comparison with controls. Scores for this factor were significantly and directly associated with positive and total symptoms in patients and inversely associated with global cognition in all participants. The results of this study replicate those of our previous publication and suggest an elevated midline-parietal gamma noise power specific to schizophrenia. The gamma noise power measure seems to be a useful tool for studying background oscillatory activity during performance of cognitive tasks.

EEG 40 Hz Coherence Decreases in REM Sleep and Ketamine Model of Psychosis

“…Do patients suffering of psychotic disorders present dysfunctions in the EEG gamma activity? Altered gamma oscillations have been observed in psychosis (95–97). In fact, schizophrenia has dysfunction of GABAergic cortical interneurons that express the calcium-binding protein parvalbumin, particularly in the prefrontal cortex (98, 99).…”

Relationship of Metacognition and Insight to Neural Synchronization and Cognitive Function in Early Phase Psychosis

“…54 The link between higher 40 Hz power with metacognition and insight may also be influenced by cortical inefficiencies associated with neural hyperexcitability, which may produce increased noise. 55,56 Increased noise would interfere with integration of ideas, emotional states and perceptions required to generate a coherent understanding of personal and social experiences. This could then result in more barren and incoherent account of mental states.…”

À propos de la modélisation cognitive de la schizophrénie : « De Frith à nos jours, actualisations ou nouveaux paradigmes ? ». Une revue de littérature systématique.

“…Chez les patients souffrant de schizophrénie, on trouve une diminution d'amplitude et une augmentation de latence du potentiel P300 (2,4,11,37,45,46,48,54,59,70,99,161,162).…”

“…Les oscillations neuronales sont un mécanisme fondamental qui permet la synchronisation de l'activité neuronale au sein et entre les structures cérébrales. Elles permettent la coordination temporelle précise des processus neuronaux qui sous-tendent la cognition, la mémoire, la perception et le comportement (4,37,48,51,64,159,162,168).…”