Stimulation-induced behavioral state

Acute, reproducible changes in affect, arousal or behavior produced directly by focal stimulation — transient mood elevation, spontaneous mirth or laughter, a sense of calm, or conversely anxiety, dread or hypomania-like activation — that depend on the site and parameters. During surgery and biomarker mapping these evoked responses are used as a fast, within-session signal that an electrode is engaging an affect-relevant circuit, complementing slow-changing clinical outcomes.

They also carry an important caution. A stimulation-induced state change is not therapeutic benefit: acute euphoria or hypomania is not durable remission, and can be an adverse effect. Because evoked affect is immediate and salient, it can also bias unblinded assessment, both the patient's and the rater's, which is one reason these states must be interpreted separately from long-term outcome.