hypoactivation

Hypoactivation refers to a pattern in which a brain region shows lower activation than is typical for a given task, condition, or comparison group. In neuroimaging, hypoactivation is usually inferred from measures such as fMRI BOLD signals or PET-derived metabolic activity, where the signal in the region of interest is reduced relative to a control condition or healthy controls. Hypoactivation can also be inferred from EEG/MEG when analogous markers of neural engagement are diminished.

Interpretation of hypoactivation depends on context. It can reflect impaired neural processing or dysfunction in the region, such as decreased engagement of the dorsolateral prefrontal cortex during working memory tasks in schizophrenia or reduced fusiform face area response to faces in autism. It can also indicate neural efficiency or strategic compensations, where less activation suffices to achieve performance or where other networks compensate for deficits.

Causes of hypoactivation are diverse and can include neurodevelopmental factors, aging, brain injury, psychiatric illness, pharmacological effects, or task design. Importantly, hypoactivation must be interpreted with caution, as differences may arise from methodological factors (scanner, analysis, baseline), task difficulty, or motion artifacts. Resting-state hypoactivation may reflect altered functional connectivity rather than task-evoked activity.

Compared with hyperactivation, which indicates greater-than-normal activity, hypoactivation emphasizes reduced engagement and is discussed alongside changes in connectivity and compensatory network dynamics in contemporary neuroimaging literature.