Lesioning

Lesioning is the deliberate destruction or disruption of tissue, typically neural tissue, to study or modify brain function. In research, lesions are used to infer the causal role of a brain region by observing changes in behavior or physiology after damage. In clinical settings, lesioning refers to surgical destruction of tissue to treat disorders such as refractory epilepsy, tremor, or other movement disorders; these procedures are now often replaced or complemented by less destructive approaches.

Methods include permanent lesions produced by surgical ablation, aspiration, electrocoagulation, or radiofrequency, and chemical lesions that use excitotoxic agents (for example ibotenic acid or kainic acid) to destroy neuronal cell bodies while sparing fibers of passage to varying degrees. Reversible approaches exist as well, enabling temporary inactivation without permanent tissue loss, such as pharmacological inactivation (e.g., GABA agonists), cooling, or newer techniques like optogenetics and chemogenetics, which can suppress activity in targeted circuits for a time.

Applications and interpretation: lesion effects must be interpreted with caution because deficits may reflect disruption of networks beyond the targeted area (diaschisis) or compensatory changes. In animals, ethical considerations regarding welfare are paramount; in humans, lesioning procedures require careful risk-benefit analysis and informed consent.

History: lesion studies have a long history in neuroscience, contributing to early brain-function mapping by researchers such as Flourens, Broca, and Wernicke. Today, lesioning is one of several tools for understanding brain function, often integrated with non-destructive imaging and modulation methods.