APA Dictionary of Psychology

adjustment by the thalamus of the brain’s responses to stimuli. The thalamus functions as a conduit, but it also serves as a gatekeeper for most of the sensory input flowing into the brain. This gate is managed by alterations in various neurotransmitter systems, thereby restricting or expanding the flow of afferent stimuli back to the rest of the brain. For example, if the brain is getting more than it needs of a stimulus, the thalamus makes adjustments to reduce the stimulation.