Impaired Temporal Lobe Processing of Preattentive Auditory Discrimination in Schizophrenia

Abstract

Feature-specific stimulus discrimination related to short-term auditory sensory memory can be studied electrophysiologically using a specific event-related potential (ERP) component termed mismatch negativity (MMN), which is generated in the auditory cortex, indexing automatic comparison of the existing memory trace to incoming novel stimuli. Previous results with electroencephalography (EEG) and magnetoencephalography (MEG) suggest that schizophrenia patients have attenuated MMN response and that preattentive auditory processing preceding MMN appears to be functionally asymmetric in schizophrenia. Here we studied parallel MMN activity of the hemispheres using a whole-head MEG by presenting stimulus blocks consisting of frequent standard and infrequent deviant tones to 15 schizophrenia patients and 19 healthy control subjects. Auditory evoked fields (AEFs) were recorded simultaneously over both auditory cortices. The equivalent current dipole (ECD) modeling revealed that patients had significant MMNm reduction (magnetic counterpart of MMN) in both temporal lobes. In addition, patients had significantly delayed MMNm in the left but not in the right hemisphere to ipsilateral auditory stimuli. These results suggest that patients with schizophrenia have impaired auditory processing in the temporal lobes underlying preattentive stimulus discrimination that is also selectively delayed in the left hemisphere.

Theta EEG oscillatory activity and auditory change detection

“…Alcohol attenuates mainly the frontal but not the temporal subcomponent (Jääskeläinen et al, 1996). It has also been proposed that the frontal component is attenuated in schizophrenia, whereas the temporal component is of normal magnitude (Baldeweg et al, 2002), but this finding has not been unequivocal (Kreitschmann-Andermahr et al, 1999;Pekkonen et al, 2002). In addition to these multiple findings suggesting a functional differentiation of the two components, the present data suggest that the neurophysiological mechanisms underlying the two components of the MMN are different as well.…”

A theoretical framework for CNS arousal

“…It declines with age, (51) and its CNS correlates have begun to be studied. (52) Preattention shows us the operation of the aroused CNS in the absence of detailed sensory or perceptual processing.…”

Assimetria cerebral e lateralização da linguagem: déficits nucleares na esquizofrenia como indicadores da predisposição genética

“…Não há unanimidade de que os aspectos críticos das anomalias sejam lateralizados. Usando magnetoencefalografia, Pekkonen et al 49 examinaram a mismatch negativity em 15 pacientes esquizofrênicos e 19 controles e constataram uma redução em ambos os hemisférios e uma demora na resposta, que foi lateralizada à esquerda. Com um desenho similar, mas combinando magnetoencefalografia com um protocolo de RM funcional em 12 pacientes e 12 controles, Kircher et al 50 encontraram uma perda de amplitude usando magnetoencefalografia em ambos os hemisférios em pacientes, mas um efeito de duração lateralizado à direita apenas em controles, isto é, a assimetria foi perdida no grupo de pacientes.…”