Question

When a movement is initiated, what is the specific term for the neural signal sent to sensory areas to distinguish self-generated sensations from external environmental stimuli?

Accepted Answer

The specific term for this neural signal is an efference copy. An efference copy is a duplicate of the motor command, which is the internal instruction sent from the motor cortex to the muscles to perform a movement. When the brain initiates a movement, it sends this duplicate signal to sensory processing areas, such as the somatosensory cortex or the cerebellum, before the movement actually occurs. This signal serves as a reference point that allows the brain to predict the sensory feedback it should receive as a result of the movement. By comparing the efference copy with the actual sensory input, the brain can filter out predictable, self-generated sensations, which is known as sensory attenuation. This process explains why you cannot tickle yourself; because the brain produces an efference copy of your own touch, it predicts the resulting sensation and dulls the neural response to it. In contrast, sensations originating from the external environment lack a matching efference copy, alerting the brain to process them as novel or important external stimuli.

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When a movement is initiated, what is the specific term for the neural signal sent to sensory areas to distinguish self-generated sensations from external environmental stimuli?