Dissecting Neural Contributions to Decision-Making: The Contribution of Brain Regions and Neuron Subtypes in Choice Prediction

The‬‭ prediction‬‭ of‬‭ an‬‭ animal's‬‭ choice‬‭ from‬‭ neural‬‭ activity‬‭ is‬‭ crucial‬‭ for‬‭ understanding‬ decision‐making‬‭ and‬‭ developing‬‭ brain–computer‬‭ interfaces.‬‭ We‬‭ here‬‭ applied‬‭ the‬‭ Steinmetz‬‭ et‬‭ al.‬‭ (2019)‬ Neuropixels‬‭ dataset‬‭ of‬‭ mice‬‭ trained‬‭ on‬‭ a‬‭ two‐alternative‬‭ visual‬‭ discrimination‬‭ on‬‭ a‬‭ steering‐wheel‬‭ task.‬‭ We‬ focused‬‭ on‬‭ five‬‭ regions‬‭ - spanning‬‭ hippocampal,‬‭ cingulate,‬‭ and‬‭ motor‬‭ areas:‬‭ dentate‬‭ gyrus‬‭ (DG),‬‭ CA3,‬ anterior‬‭ cingulate‬‭ area‬‭ (ACA),‬‭ primary‬‭ motor‬‭ cortex‬‭ (MOp)‬‭ and‬‭ secondary‬‭ motor‬‭ cortex‬‭ (MOs).‬‭ We‬‭ first‬ trained‬‭ time‐resolved,‬‭ cross‐validated‬‭ logistic‐regression‬‭ classifiers‬‭ within‬‭ sliding‬‭ 300‬‭ ms‬‭ windows‬‭ (50‬‭ ms‬ steps)‬‭ to‬‭ decode‬‭ both‬‭ the‬‭ direction‬‭ (left‬‭ vs.‬‭ right)‬‭ and‬‭ correctness‬‭ of‬‭ each‬‭ choice‬‭ from‬‭ population‬‭ spiking.‬ Accuracy‬‭ for‬‭ choice‬‭ decoding‬‭ rose‬‭ systematically‬‭ from‬‭ the‬‭ hippocampal‬‭ subfields‬‭ (median‬‭ ≈‬‭ 0.55–0.58)‬‭ to‬ ACA‬‭ (≈‬‭ 0.70)‬‭ to‬‭ motor‬‭ areas‬‭ (MOs/MOp‬‭ ≈‬‭ 0.80–0.88),‬‭ whereas‬‭ trial‬‭ outcome‬‭ decoding‬‭ was‬‭ uniformly‬ high‬‭ (≈‬‭ 0.75–0.85)‬‭ across‬‭ regions.‬‭ Onset‐latency‬‭ analysis‬‭ revealed‬‭ that‬‭ ACA‬‭ and‬‭ DG‬‭ were‬‭ the‬‭ only‬‭ ones‬ with‬‭ discrete,‬‭ post‐stimulus‬‭ choice‬‭ accuracy‬‭ increases‬‭ above‬‭ pre‐stimulus‬‭ baseline‬‭ +‬‭ 2‬‭ ×‬‭ SEM‬‭ (occurring‬ at‬‭ 245‬‭ ms‬‭ for‬‭ ACA‬‭ and‬‭ 295‬‭ ms‬‭ for‬‭ DG).‬‭ Cross‐temporal‬‭ generalization‬‭ revealed‬‭ that‬‭ the‬‭ hippocampus‬ contained‬‭ fleeting‬‭ choice‬‭ representations,‬‭ whereas‬‭ the‬‭ motor‬‭ cortex‬‭ exhibited‬‭ extended,‬‭ time-invariant‭ coding,‬‭ as‬‭ would‬‭ be‬‭ expected‬‭ from‬‭ downstream‬‭ motor‐planning‬‭ signals.‬‭ Finally,‬‭ contrasting‬‭ high‐‬‭ versus‬ low‐contrast‬‭ trials‬‭ as‬‭ a‬‭ proxy‬‭ for‬‭ task‬‭ difficulty,‬‭ we‬‭ found‬‭ that‬‭ stimulus‬‭ strength‬‭ modulates‬‭ the‬‭ timing‬‭ and reliability‬‭ of‬‭ choice‬‭ signals.‬‭ Specifically,‬‭ higher‬‭ contrast‬‭ stimuli‬‭ accelerates‬‭ and‬‭ stabilizes‬‭ decision‐related‬ activity‬‭ along‬‭ this‬‭ ACA→motor‬‭ axis.‬‭ Together,‬‭ these‬‭ results‬‭ describe‬‭ a‬‭ hierarchical,‬‭ contrast‐sensitive‬ flow‬‭ of‬‭ choice‬‭ information‬‭ from‬‭ medial‬‭ temporal‬‭ through‬‭ prefrontal‬‭ to‬‭ motor‬‭ circuits‬‭ during‬‭ perceptual‬ decisions.‬