Biology subjects

Rodrigues-Vaz, I.

Publications and source records attributed to Rodrigues-Vaz, I..

3 recordsLinked to original sources

bioRxiv2025

Striatal ensembles specify and control granular forelimb actions

The striatum is classically thought to modulate action vigor and reinforcement, but whether it specifies and controls ongoing actions at a fine scale remains unclear. Here, we test whether striatal activity can resolve and control actions as granular as distinct patterns of muscle co-contraction within the same limb. We developed a closed-loop system combining two-photon imaging and holographic optogenetics to identify and manipulate action-specific striatal ensembles in real time. Mice performed isometric push or pull actions engaging the same forelimb muscles with different activation patterns. Ensembles of both D1- and D2-spiny projection neurons encoded action identity with equal fidelity. Causal stimulation of small ensembles biased ongoing force, but only when the ensembles encoded the ongoing action. These results show that the striatum specifies and controls ongoing actions in real time at a previously unappreciated granularity, redefining its role in motor control.

neuroscience↗

bioRxiv2025

Internal and external contexts drive distinct dynamics in shared action-encoding striatal neurons

Animals can initiate movements either in response to external cues or from internal drive, yet how the brain flexibly supports both remains unclear. Disorders such as Parkinsons disease disrupt these modes differently, suggesting distinct underlying mechanisms. Such differences could arise from specialized circuits dedicated to each action mode or from shared neuronal populations that shift their dynamics across contexts. To distinguish between these possibilities, we performed two-photon calcium imaging in the dorsolateral striatum as mice executed the same lever press either spontaneously or in response to a cue, enabling direct comparison of internally and externally triggered actions. Unsupervised clustering revealed subpopulations of neurons modulated during cue, movement, or post-action periods. Critically, the same neurons were tuned to movement across initiation contexts. However, the dynamics of this shared population evolved within distinct "context" and "action" subspaces, even before movement initiation. Both dopamine D1- and D2-receptor-expressing spiny projection neurons contributed to both subspaces, with D1-SPNs more active at the time of the sensory stimulus. These results show that context shapes neural dynamics within a shared movement-encoding population, revealing a context-generalizable striatal code that supports flexible movement initiation across internal and external drives.

neuroscience↗

bioRxiv2017

Single-Trial Inhibition of Anterior Cingulate Disrupts Model-based Reinforcement Learning in a Two-step Decision Task.

The anterior cingulate cortex (ACC) is implicated in learning the value of actions, but it remains poorly understood whether and how it contributes to model-based mechanisms that use action-state predictions and afford behavioural flexibility. To isolate these mechanisms, we developed a multi-step decision task for mice in which both action-state transition probabilities and reward probabilities changed over time. Calcium imaging revealed ramps of choice-selective neuronal activity, followed by an evolving representation of the state reached and trial outcome, with different neuronal populations representing reward in different states. ACC neurons represented the current action-state transition structure, whether state transitions were expected or surprising, and the predicted state given chosen action. Optogenetic inhibition of ACC blocked the influence of action-state transitions on subsequent choice, without affecting the influence of rewards. These data support a role for ACC in model-based reinforcement learning, specifically in using action-state transitions to guide subsequent choice. HighlightsO_LIA novel two-step task disambiguates model-based and model-free RL in mice. C_LIO_LIACC represents all trial events, reward representation is contextualised by state. C_LIO_LIACC represents action-state transition structure, predicted states, and surprise. C_LIO_LIInhibiting ACC impedes action-state transitions from influencing subsequent choice. C_LI

neuroscience↗