Biology subjects

Rizor, E.

Publications and source records attributed to Rizor, E..

3 recordsLinked to original sources

bioRxiv2024

Dissociation of novel open loop from ventral putamen to motor areas from classic closed loop in humans II: task-based function

Humans ubiquitously increase the speed of their movements when motivated by incentives (i.e., capturing reward or avoiding loss). The complex interplay between incentivization and motor output is pertinent for unpacking the functional profiles of different circuits that link the basal ganglia with motor cortical areas. Here, we analyzed the functional profile of nodes forming two circuits involving putamen and motor cortical areas: the traditional "closed-loop circuit" (CLC) from sensorimotor dorsal putamen (PUTd) and a putative "open-loop circuit" (OLC) from ventral putamen (PUTv). Establishing differential function between CLC and OLC is particularly relevant for therapeutic approaches to Parkinsons disease, where OLC function is hypothesized to be relatively spared by the disease process. In a large sample fMRI study, 68 healthy controls executed speeded reaches with a joystick under different levels of incentivization to accurately hit precision targets. We dissociated effects of "incentive per se" (i.e., changes in brain activity when an upcoming movement obtains a reward or avoids a loss) from "RT effects" (i.e., brain activity that directly scales with adjustments to movement initiation time). Incentive per se was observed across sites in both CLC and OLC. However, RT effects were primarily in nodes of the OLC and motor sites, consistent with the hypothesized anatomy and function of OLC. Our findings additionally suggest valence might mediate when incentives recruit OLC to more prominent control of motor behavior.

neuroscience↗

bioRxiv2023

Cardiac-sympathetic contractility and neural alpha-band power: cross-modal collaboration during approach-avoidance conflict

As evidence mounts that the cardiac-sympathetic system reacts to challenging cognitive settings, we ask if these responses are passive companions or if they are instead fundamentally intertwined with cognitive function. Healthy human participants performed an approach-avoidance paradigm, trading off monetary reward for painful electric shock, while we recorded simultaneous neural and cardiac signals. Participants were reward-sensitive, but also experienced approach-avoidance "conflict" when the subjective appeal of the reward was near equivalent to the revulsion of the cost. Drift-diffusion model parameters revealed that participants managed conflict in part by integrating larger volumes of evidence into choices (wider decision boundaries). Late alpha-band (neural) dynamics suggested that widening decision boundaries served to combat reward-sensitivity and spread attention more fairly to all dimensions of available information. Independently, wider boundaries were also associated with cardiac "contractility" (an index of sympathetically-mediated positive inotropy). We also saw evidence of conflict-specific collaboration between the neural and cardiac-sympathetic signals. Specific to states of conflict, the alignment (i.e., product) of alpha dynamics and contractility were associated with a further widening of the boundary, independent of either signals singular influence. Cross-trial coherence analyses provided additional support for a direct role of cardiac-sympathetics in nurturing fair assessment of information streams during conflict by disrupting the prepotent reward signals. We conclude that cardiac-sympathetic activity is not a mere companion, rather it is a critical component collaborating with cognitive processes to combat reward-sensitivity during the approach-avoidance conflict.

physiology↗

bioRxiv2022

Decision heuristics in contexts exploiting intrinsic skill

Heuristics can inform human decision making in complex environments through a reduction of computational requirements (accuracy-resource trade-off) and a robustness to overparameterisation (less-is-more). However, tasks capturing the efficiency of heuristics typically ignore action proficiency in determining rewards. The requisite movement parameterisation in sensorimotor control questions whether heuristics preserve efficiency when actions are nontrivial. We developed a novel action selection-execution task requiring joint optimisation of action selection and spatio-temporal skillful execution. Optimal choices could be determined by a simple spatial heuristic, or by more complex planning. Computational models of action selection parsimoniously distinguished human participants who adopted the heuristic from those using a more complex planning strategy. Broader comparative analyses then revealed that participants using the heuristic showed combined decisional (selection) and skill (execution) advantages, consistent with a less-is-more framework. In addition, the skill advantage of the heuristic group was predominantly in the core spatial features that also shaped their decision policy, evidence that the dimensions of information guiding action selection might be yoked to salient features in skill learning. Author SummaryWe often must choose between actions and then execute them, e.g., a tennis player chooses between a forehand and backhand and then skilfully executes the shot. To select actions, the player might plan their action with either shot, and select whichever simulated outcome is more advantageous. However, a more efficient approach might instead be to use a "heuristic", i.e., a simpler rule, such as, forehand always on one side of the court, and backhand on the other. In this work, we look at whether styles of planning are related to physical skill performing actions, e.g., would a more skillful tennis player be more likely to use planning or a heuristic? We use a new task that requires people to choose and execute complex actions. Regarding choices, we use computational modeling to identify which people use some degree of planning, and which people use a simpler heuristic. Then, regarding action execution, we reveal that heuristic decision makers are in fact more skilled. However, they are not superiorly skilled in all aspects of performance, showing an advantage solely in the aspect of skill most closely linked to the information (spatial) they use for their heuristic. We therefore reveal the first ever evidence that a relation exists between the complexity of our action-related decisions and how broadly we learn associated motor behaviour.

neuroscience↗