MIT neuroscientists report in Science a circuit that links a sensory decision region with a structure that evaluates recent sensory changes. The pathway runs from the thalamic lateral posterior nucleus (LP in mice, the pulvinar in humans) to the anterior cingulate cortex (ACC), allowing the brain to compare what just happened with what is happening now and decide whether to keep or update a judgment.
Mice were trained on a visual game where dots drifted left or right; both the direction and the proportion of coherent dots varied across trials. The animals had to infer the overall motion trend. Researchers recorded LP‑ACC activity with two‑photon microscopy and manipulated the circuit with optogenetics while monitoring performance.
Behaviorally, mice tended to repeat a correct choice when the new cue resembled the previous one, but switched when the cue differed markedly. Optogenetic activation of the left‑hemisphere pathway reduced the likelihood of choosing rightward motion, whereas right‑hemisphere activation increased it. In both cases, the magnitude of the bias scaled with the difference between the current and previous cues, indicating a causal role for the LP‑ACC loop in using recent sensory history for comparison.
Imaging analysis showed that LP primarily conveys a history‑referenced sensory comparison, while ACC transforms this signal into neural activity that predicts the final choice. In other words, the pulvinar advises the frontal cortex on the degree of change, and the ACC decides whether the guess should be revised.
Beyond basic neuroscience, the findings may inform studies of autism, where predictive processing of sensory input is often altered. The work was funded by NIH, MURI, the Simons Foundation, and others.
Blogger's Review: By combining a sophisticated behavioral paradigm with cutting‑edge optogenetics, this study provides a clear mechanistic picture of how recent sensory history shapes decision‑making. It opens new avenues for probing attention, perception, and related disorders.