Lack of neural load modulation explains attention and working memory deficits in first-episode schizophrenia.

OBJECTIVE: Although working memory (WM) deficits are well-recognized core features of schizophrenia, the underlying pathophysiological substrates of impairment in early psychosis before medication remain unclear. One possibility is that deficits in selective attention contribute to WM impairment. METHODS: EEG was acquired from 25 first-episode drug-naive schizophrenia patients and 26 matched controls while they performed a WM task. RESULTS: Compared with controls, schizophrenia patients showed a deficit in WM capacity in both behavioral and electrophysiological measures. Notably, the increased parieto-occipital pre-encoding stimulus alpha power in patients with schizophrenia predicted their subsequent reduced N2pc and symptom severity, whereas this relationship was absent in controls. Moreover, lacking load effect in neural activities predicted the serious impairment in behavior for schizophrenia. CONCLUSIONS: This pilot study provides preliminary evidence that the lack of load effect in neural activities may serve as potential underlying mechanisms for the impaired selective attention and WM capacity in schizophrenia. Our results emphasize the importance of pre-encoding stimulus alpha power in first-episode drug-naive schizophrenia. SIGNIFICANCE: These findings provide a neurophysiological correlate for the subjective reports of working memory deficits in schizophrenia and indicate the potential effective targets for clinical intervention.

Sound localization and auditory selective attention in school-aged children with ADHD.

This study aimed to identify the neurophysiologic bases of auditory attention deficits in children with attention-deficit/hyperactivity disorder (ADHD), focusing on the electroencephalography component of auditory spatial selective attention [the N2 anterior contralateral component (N2ac)]. EEG data were collected from 7- to 11-year-old children with ADHD (n = 54) and age-, sex-, and IQ-matched typically developing (TD) children (n = 61), while they performed an auditory spatial selective task. For behavior, the children with ADHD showed a shorter reaction time (RT) but a higher RT coefficient of variability (RTCV) than TD children. For ERPs, the TD group showed a significant "adult-like" N2ac component; however, the N2ac component was absent in children with ADHD. More importantly, the smaller N2ac component could predict longer RT in both groups, as well as higher severity of inattentive symptoms in children with ADHD. Our results indicated that 7- to 11-year-old TD children have developed an "adult-like" ability to balance auditory target selection and distractor suppression; the absence of N2ac in children with ADHD provided novel evidence supporting their dysfunctional auditory spatial selective attention.