Quantitative EEG of frontal and central cortices during calm memory retrieval in schizophrenia

Altered neural oscillations are a hallmark of cognitive and emotional dysregulation in schizophrenia. Theta-band activity, particularly in frontal and central regions, has been associated with working memory, internal attention, and relaxed cognitive states. However, the role of theta dynamics during tasks that integrate memory retrieval with a calm, internally directed state remains unclear.

Thirty individuals with schizophrenia participated in a structured memory recall task embedded within the Brain Mapping Performance (BMP) protocol. Three conditions were examined: calm (eyes closed with guided internal focus), resting (eyes open), and active memory task. Quantitative EEG (QEEG) was recorded from 12 scalp sites, with analyses focused on theta relative power and theta/beta ratio at frontal, central, and temporal sites (Fp1, Fz, F4, F7, Cz, T3). Behavioral performance and self-reported calmness were also assessed. Repeated-measures ANOVA was used to evaluate condition and electrode-site effects.

Theta relative power was highest during the calm condition and decreased during resting and memory task conditions (p < .001), with prominent activity at frontal-midline (Fz) and central (Cz) sites. The memory task was associated with reduced theta dominance and increased task demands, reflected by lower accuracy and longer completion time (p < .05). Theta/beta ratio followed a similar descriptive pattern, with higher values during calm states and lower values during active task engagement. Exploratory correlation analyses indicated associations between EEG activity and behavioral performance.

Frontal and central theta activity may reflect modulation between internally directed calm states and active processing in schizophrenia. The highest theta activity observed during calm conditions suggests that internally focused states may support neural readiness, while task-related reductions reflect increased executive demand. These findings support the use of QEEG-based measures within occupation-integrated paradigms, such as BMP, for assessing and guiding cognitive-emotional regulation in psychiatric rehabilitation.