Sensory systems are bound to sensory receptors – vision to the retina, hearing to the cochlea. There is a striking exception; the sense of time is precise and guides all our behaviours, yet time receptors do not exist. The brain must build up a neuronal representation of time using circuits free from any dedicated receptors. New research carried out by the SISSA Tactile Perception and Learning Lab, directed by Mathew Diamond, investigates the role of a specific area of the rat brain, the dorsolateral striatum (DLS) in time perception. The report argues that this brain region holds a clock for absolute time, but that clock is not converted into a percept of elapsed time.
“Recent work suggests that dorsal striatum is critical in encoding the perception of time” Alessandro Toso, first author of the paper, says. “We show for the first time that DLS, while a reliable counter of elapsed time, is likely not the substrate of the perceived duration of ongoing sensory stimuli. Our current work points to other mechanisms for generating the feeling of time.”
As rats judged the duration of sensory stimuli, precise temporal information was in fact contained within DLS neuronal activity. The DLS time code does not solve the perception puzzle, however, since the code was more tightly coupled to the sequence of events than to the rat’s judgment of stimulus duration.