Biology subjects

Dundon, N. M.

Publications and source records attributed to Dundon, N. M..

17 recordsLinked to original sources

bioRxiv2026

Neural Control of Autonomic Arousal During Threat Anticipation Revealed by High-Resolution Cardiac Contractility

The sympathetic nervous system prepares the organism for adaptive action by shaping physiological, affective, and behavioral responses to environmental demands. Yet, how sympathetic signals dynamically couple with neural systems supporting emotional experience and behavior remains poorly understood, in part because common indices such as skin conductance responses lack sufficient temporal resolution to track these dynamics. Here, we evaluated trans-radial electrical bioimpedance velocimetry (TREV), a non-invasive measure of beat-to-beat cardiac contractility, and compared it with skin conductance responses during threat anticipation and simultaneous fMRI. Participants (n=60) completed a threat-of-shock paradigm requiring goal-directed action. Cardiac contractility increased during threat anticipation, covaried with skin conductance responses, and independently predicted self-reported emotional intensity. Critically, threat-related increases in contractility--but not skin conductance--tracked threat-related modulation of activation in dorsomedial prefrontal cortex, posterior parietal cortex, and cerebellum, with contractility-modulated cerebellar activation predicting faster motor responses under threat. These findings establish TREV-derived cardiac contractility as a physiological signal linking sympathetic drive with neural responding, emotional experience, and adaptive behavioral mobilization during emotion-guided action.

neuroscience↗

bioRxiv2026

Distinct amygdalar pathways to frontopolar cortex and medial temporal lobe support temporal memory for emotional events

Growing evidence suggests that emotion shapes temporal aspects of memory--such as remembering when an event occurred--yet the neural bases of these effects remain unclear. Prior work indicates that temporal-context representations in memory are supported by the function of medial temporal lobe (MTL) and prefrontal regions with privileged access to amygdala-originated affective signals, which may mediate emotional influences on temporal memory--including hippocampus, perirhinal cortex, and lateral frontopolar cortex (FPl). To test whether these candidate pathways shape temporal memory for emotional events, participants encoded trial-unique negative and positive images in the scanner, followed by a surprise temporal memory task. We found that more negative stimuli were associated with greater amygdala activation and lower temporal-memory error for when emotional images occurred. Replicating and extending prior work, higher stimulus-evoked multivoxel pattern similarity in the hippocampus (between trials) and FPl (within and between trials) was associated with higher temporal memory errors. Notably, greater amygdala responding to emotional images predicted higher between-trial pattern similarity in the hippocampus, but lower within- and between-trial similarity in FPl. Amygdala engagement was also correlated with greater perirhinal activation, which in turn predicted stronger item memory and a recency bias in temporal memory estimates. Collectively, these findings reveal distinct--and opposing--modulatory effects of amygdala-FPl and amygdala-MTL pathways on temporal memory, with the potential to sharpen and blur memory for when emotional events occurred. Significance statementEmotional events influence how we remember time. Prior work implicates function of the lateral frontal pole (FPl) and medial temporal lobe (MTL) regions--including hippocampus and perirhinal cortex--in temporal memory. Yet, whether and how these areas support temporal memory for emotional events remains unclear. Using trial-unique emotional images, we found that negative-emotional valence was associated with stronger amygdala activation and temporal-memory accuracy. Higher pattern similarity in hippocampus and FPl predicted worse temporal memory. Notably, amygdala activation predicted higher between-trial hippocampal pattern similarity but lower within-trial FPl similarity. Perirhinal engagement, which correlated with amygdala activation and item memory, predicted a recency bias in temporal-memory judgments. Together, these findings reveal distinct amygdala-MTL and amygdala-prefrontal pathways through which emotion shapes temporal memory.

neuroscience↗

bioRxiv2025

Cardiac-sympathetic state predicts action restraint, gated by demonstrated agency

Withholding action until the appropriate moment is a core challenge of motivated behavior. Using beat-to-beat cardiac contractility during an incentivized reaching task, we show that cardiac-sympathetic outflow predicts action restraint. Under high-reward conditions that induce a speed-accuracy tradeoff, reduced contractility at the time of instruction preceded premature responses (false starts). Under high-loss-avoidance conditions, elevated pre-movement contractility predicted slower, more controlled initiation, but only among participants with above-median task success. These findings suggest cardiac-sympathetic engagement does not simply serve mobilization but flexibly supports context-appropriate action regulation, with recruitment for restraint gated by demonstrated agency.

physiology↗

bioRxiv2025

Incentive valence differentially engages open- and closed-loop basal ganglia circuits during movement initiation

Incentives modulate voluntary movement, yet the circuitry channeling these signals into motor output remains unclear. Classical models emphasize a closed-loop circuit (CLC) linking dorsal putamen (PUTd) with motor cortex, but this pathway is anatomically segregated from affective processing regions. Anatomical and clinical evidence point to an alternative: an open-loop circuit (OLC) from ventral putamen (PUTv) that may route affective signals to motor cortex. Here, we conducted two experiments to test whether a functional OLC exists in humans and whether it is differentially engaged by incentive conditions. First, in 7 T resting-state fMRI (multi-echo), PUTv showed robust functional connectivity with both affective and motor regions, including the cingulate motor area (CMA), even after accounting for PUTd variance. This connectivity pattern supports the plausibility of an independent pathway linking affective basal ganglia regions to the motor cortex. Second, in 3 T task fMRI (incentivized reaching), jackpot (high-reward) and robber (high-loss avoidance) incentive conditions produced distinct behavioral and neural signatures. Jackpot produced a speed-accuracy trade-off, with faster movement initiation but more false starts. Neurally, this coincided with engagement (BOLD responses relevant for initiation speed) being reduced in CLC nodes but not in OLC. Robber, in contrast, eliminated engagement in both OLC and CLC nodes, instead recruiting stopping-related regions (e.g., STN), consistent with an avoidance phenomenology. Together, these findings support a versatile architecture for movement initiation that flexibly engages distinct cortico-subcortical circuits depending on incentive phenomenology, and offer a candidate mechanism through which affective salience and valence modulate voluntary movement. Significance StatementAffective signals profoundly influence movement, yet the mechanisms linking motivationally relevant contexts with motor behavior remain unclear. Combining ultra-high field (7 T) connectomics with task-based (3 T) neuroimaging, we provide the first systems-level evidence in humans for such a mechanism: a ventral putamen-centered open-loop circuit (OLC) connecting affective and motor areas, operating alongside the canonical dorsal putamen-centered closed-loop sensorimotor circuit (CLC). Critically, the phenomenological quality of incentive (how it is construed as reward versus threat) rather than magnitude alone, likely determines which circuit dominates during movement initiation. These findings help to explain paradoxical kinesia in Parkinsons disease, where affective contexts can bypass degraded sensorimotor circuits, and establish foundations for context-based therapeutic interventions.

neuroscience↗

bioRxiv2025

Integrated Representations of Threat and Controllability in the Lateral Frontal Pole

Emotional processing is ubiquitous in everyday life, informing goal pursuit not only in response to current demands, but also in anticipation of future outcomes. Lateral prefrontal (LPFC) function supports cognitive control, and emerging evidence suggests a unique role for its anterior-most region--the lateral frontal pole (FPl)--in integrating putatively amygdala-originated emotion signals with goal information. However, whether these organizational properties of LPFC are expressed during the anticipation of future threat remains unknown. Here, we used FIR modeling and pattern similarity analysis to examine dynamic engagement and representational properties of distinct LPFC regions during threat anticipation requiring goal-directed action. Healthy participants (n=67) were scanned during a threat-of-shock paradigm consisting of a prolonged (18s) countdown to possible shock administration. Threat unpleasantness and controllability were manipulated orthogonally: in controllable trials, participants could avoid an unpleasant or mild shock by making a successful time-sensitive response; in uncontrollable trials, shocks were administered regardless of performance. LPFC robustly coded for anticipated threat unpleasantness, with FPl showing the strongest modulation by threat unpleasantness and controllability relative to caudal and mid-LPFC regions. Caudal and mid-LPFC maintained independent representations of threat unpleasantness and controllability. In contrast, FPl held conjunctive threat-and-controllability representations, which were associated with successful motor performance following anticipation of unpleasant shocks. Stronger conjunctive FPl representations were also associated with greater inverse amygdala-FPl coupling. Together, these findings provide insight into LPFC organization under naturalistic emotional challenges and highlight a key role for FPl in integrating affective and control-related information during threat anticipation to support goal-directed action. Significance StatementAnticipating emotionally-charged events--such as a painful outcome we may or may not be able to avoid--requires integrating emotion and control to guide behavior. However, the neural mechanisms through which emotional states influence goal-directed behavior in naturalistic, anticipatory emotional contexts remain unclear. Using a threat-of-shock paradigm and multivariate analyses we show that the anterior-most region of the lateral prefrontal cortex (LPFC)--the lateral frontal pole (FPl)--uniquely integrates information about the emotional unpleasantness and controllability of a future event, and that the strength of this integrated signal predicts better behavioral performance. These findings extend models of LPFC function to naturalistic, emotional contexts, and highlight the FPl as a key node for translating emotional and behavioral-control information into adaptive action.

neuroscience↗

bioRxiv2024

Neural Encoding of Direction and Distance across Reference Frames in Visually Guided Reaching

Goal-directed actions require transforming sensory information into motor plans defined across multiple parameters and reference frames. Substantial evidence supports the encoding of target direction in gaze- and body-centered coordinates within parietal and premotor regions. However, how the brain encodes the equally critical parameter of target distance remains less understood. Here, using Bayesian pattern component modeling of fMRI data during a delayed reach-to-target task, we dissociated the neural encoding of both target direction and the relative distances between target, gaze, and hand at early and late stages of motor planning. This approach revealed independent representations of direction and distance along the human dorsomedial reach pathway. During early planning, most premotor and superior parietal areas encoded a targets distance in single or multiple reference frames and encoded its direction. In contrast, distance encoding was magnified in gaze- and body-centric reference frames during late planning. These results emphasize a flexible and efficient human central nervous system that achieves goals by remapping sensory information related to multiple parameters, such as distance and direction, in the same brain areas. Significance statementMotor plans specify various parameters, e.g., target direction and distance, each of which can be defined in multiple reference frames relative to gaze, limb, or head. Combining fMRI, a delayed reach-to-target task, and Bayesian pattern component modeling, we present evidence for independent goal-relevant representations of direction and distance in multiple reference frames across early and late planning along the dorsomedial reach pathway. Initially, areas encoding distance also encode direction, but later in planning, distance encoding in multiple reference frames was magnified. These results emphasize central nervous system flexibility in transforming movement parameters in multiple reference frames crucial for successful goal-directed actions and have important implications for brain-computer interface technology advances with sensory integration.

neuroscience↗

bioRxiv2024

Sensory context of initiation-cue modulates action goal-relevant neural representations

The ability to produce goal-directed movement relies on the integration of diverse sources of sensory information specific to the task goal. Neural representations of goal-relevant features, such as target location and gaze direction, have been well studied in sensorimotor areas. It remains less clear whether goal-relevant motor representations are influenced by sensory changes to initiation-relevant information, such as a go-cue that provides no information about target location. We used Bayesian pattern component modelling of fMRI data during a delayed reach task with either visual or audiovisual go-cues to explore whether neural representations of goal-related features in sensorimotor areas are modulated by changes to initiation-relevant sensory information. We found that representations of target direction and gaze direction in the primary sensory areas, motor areas, and posterior parietal cortex, were sensitive to whether a reach was cued with a visual or audiovisual go-cue. These findings indicate that the central nervous system flexibly delegates the tasks of where to move and when to move based on available sensory context, even if initiation-relevant stimuli provide no additional information about target location.

neuroscience↗

bioRxiv2024

Dissociation of putative open loop circuit from ventral putamen to motor cortical areas in humans I: high-resolution connectomics

Human movement is partly organized and executed by cortico-basal ganglia-thalamic closed-loop circuits (CLCs), wherein motor cortical areas both send inputs to and receive feedback from the basal ganglia, particularly the dorsal putamen (PUTd). These networks are compromised in Parkinsons disease (PD) due to neurodegeneration of dopaminergic inputs primarily to PUTd. Yet, fluid movement in PD can sporadically occur, especially when induced by emotionally arousing events. Rabies virus tracing in non-human primates has identified a potential alternative motor pathway, wherein the ventral putamen (PUTv) receives inputs from subcortical limbic areas (such as amygdala nuclei) and sends outputs to motor cortical areas putatively via the nucleus basalis of Meynert (NBM). We hypothesize that this separable open loop circuit (OLC) may exist in humans and explain the preservation of movement after CLC degradation. Here, we provide evidence for the normal human OLC with ultra-high field (7T), multi-echo functional magnetic resonance imaging. We acquired resting-state functional connectivity (FC) scans from 21 healthy adults (avg. age = 29, 12M/9F, all right-handed) and mapped left-hemisphere seed-to-voxel connectivity to assess PUTv FC with putative subcortical nodes and motor cortical areas. We found that putative OLC node (basolateral amygdala, NBM) FC was greater with PUTv (p < 0.05), while CLC subcortical seed (ventrolateral nucleus of thalamus) FC was greater with PUTd (p<0.01). Striatal FC patterns varied across cortical motor areas, with cingulate (p < 0.0001) and supplementary (p < 0.0001) motor areas showing greater FC with PUTv vs. nucleus accumbens. SMA had greater FC with PUTd vs. PUTv (p < 0.0001), while cingulate and primary motor areas showed no significant differences in FC between PUTd and PUTv (p > 0.1). Collectively, these results suggest that PUTv is functionally connected to motor cortical areas and may be integrated into a separable motor OLC with subcortical limbic inputs.

neuroscience↗

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↗

bioRxiv2023

Menstrual cycle-driven hormone concentrations co-fluctuate with white and grey matter architecture changes across the whole brain

Cyclic fluctuations in hypothalamic-pituitary-gonadal axis (HPG-axis) hormones exert powerful behavioral, structural, and functional effects through actions on the mammalian central nervous system. Yet, very little is known about how these fluctuations alter the structural nodes and information highways of the human brain. In a study of 30 naturally cycling women, we employed multidimensional diffusion and T1-weighted imaging during three estimated menstrual cycle phases (menses, ovulation, mid-luteal) to investigate whether HPG-axis hormone concentrations co-fluctuate with alterations in white matter (WM) microstructure, cortical thickness (CT), and brain volume. Across the whole brain, 17{beta}-estradiol and luteinizing hormone (LH) concentrations were directly proportional to diffusion anisotropy (FA), while follicle-stimulating hormone (FSH) was directly proportional to cortical thickness. Within several individual regions, FSH and progesterone demonstrated opposing associations with mean diffusivity and cortical thickness. These regions mainly reside within the temporal and occipital lobes, with functional implications for the limbic and visual systems. Lastly, progesterone was associated with increased tissue and decreased CSF volumes, with total brain volume remaining unchanged. These results are the first to report simultaneous brain-wide changes in human WM microstructure and cortical thickness coinciding with menstrual cycle-driven hormone rhythms. Strong brain-hormone interaction effects may not be limited to classically known HPG-axis receptor-dense regions.

neuroscience↗

bioRxiv2022

No effects of offline high frequency transcranial magnetic stimulation to posterior parietal cortex on the choice of which hand to use to perform a reaching task.

The current study used a high frequency TMS protocol known as continuous theta burst stimulation (cTBS) to test a model of hand choice that relies on competing interactions between the hemispheres of the posterior parietal cortex. Based on the assumption that cTBS reduces cortical excitability, the model predicts a significant decrease in the likelihood of selecting the hand contralateral to stimulation. An established behavioural paradigm was used to estimate hand choice in each individual, and these measures were compared across three stimulation conditions: cTBS to the left posterior parietal cortex, cTBS to the right posterior parietal cortex, or sham cTBS. Our results provide no supporting evidence for the interhemispheric competition model. We find no effects of cTBS on hand choice, independent of whether the left or right posterior parietal cortex was stimulated. Our results are nonetheless of value as a point of comparison against prior brain stimulation findings that, in contrast, provide evidence for a causal role for the posterior parietal cortex in hand choice. HighlightsO_LIHigh-frequency TMS applied to the left and right posterior parietal cortex, separately, did not produce reliable aftereffects on hand choice. C_LIO_LIResponse times to initiate actions were significantly increased when reaching near the point in space where hand choice was equally probable. C_LI

animal behavior and cognition↗

bioRxiv2022

Trans-Radial Electrical Bioimpedance Velocimetry: A Novel Method for Detecting Cardiac Contractility

Increasing insight into the complex human response to external states can be captured by measuring event-related cardiac sympathetic activity. However existing assays are either confounded by influence from other branches of the autonomic system, or require preprocessing steps that eliminate moment-to-moment capture of fluctuation. We accordingly tested a novel device (TREV) that measures cardiac impedance directly from the radial and ulnar arteries of the human forearm, while healthy human participants performed a small number of trials of a task known to elicit sympathetic drive, a maximum-strength grip task. TREV recorded robust estimates of contractility at each heartbeat, that allowed fully automated beatwise estimations. TREV further reliably described credible group-level departures from baseline aligned with each individual grip in the task. We conclude that the device can be a useful addition to a broadening field exploring event-related sympathetic perturbations.

physiology↗

bioRxiv2022

An Accelerometer Based Heart Monitor to Measure Changes of the Autonomic Nervous System

The electrocardiogram (ECG) and impedance cardiography (ICG) are typically combined to estimate electromechanical features such as the pre-ejection period (PEP) and left ventricular ejection time (LVET); indicators of changes in the cardiac specific drive of the autonomic nervous system (ANS). Current methods of ICG are time intensive in subject preparation and the measurements are vulnerable to non-reproducible subject-specific electrode configuration. Furthermore, analysis of impedance waveforms can be time consuming and labeling of key time points can suffer from experimenter bias. Here we present a wearable heart monitor that includes ECG, but replaces the commonly used 8 ICG electrodes with a single accelerometer (ACC) placed at the suprasternal notch. The ACC indirectly measures movement of the arterial pulse wave as blood is ejected into the aorta and great vessels. The resulting ACC waveform is processed into two smooth and readily identified waves, corresponding to the timing of the opening and closing of the aortic valve. We tested the ACCs utility and reliability for tracking cardiac ANS tone by comparing PEP and LVET measurements obtained simultaneously with conventional ICG and the ACC. Participants were recorded in the sitting and supine position with ECG, ICG, and ACC. While seated, they engaged in a classic physical stress task known to modulate ANS activity. There were obvious and significant associations between ICG and ACC estimates of PEP and LVET derivatives with respect to time. These findings support ACC as a complementary method for tracking ANS that is robust, time efficient, and readily accessible to researchers.

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↗

bioRxiv2019

Sympathetic and parasympathetic involvement in time constrained sequential foraging

Appraising sequential offers relative to an unknown future opportunity and a time cost requires an optimization policy that draws on a learned estimate of an environments richness. Converging evidence points to a learning asymmetry, whereby estimates of this richness update with a bias toward integrating positive information. We replicate this bias in a sequential foraging (prey selection) task and probe associated activation within two branches of the autonomic system, sympathetic and parasympathetic branches, using trial-by-trial measures of simultaneously recorded cardiac autonomic physiology. In general, lower value offers were accepted during periods of autonomic drive, both in the sympathetic (shorter pre-ejection period PEP) and parasympathetic (higher HF HRV) branches. In addition, we reveal a unique adaptive role for the sympathetic branch in learning. It was specifically associated with adaptation to a deteriorating environment: it correlated with both the rate of negative information integration in belief estimates and downward changes in moment-to-moment environmental richness, and was predictive of optimal performance on the task. The findings are consistent with a parallel processing framework whereby autonomic function serves both learning and executive demands of prey selection.\n\nSignificance statementThe value of choices (accepting a job) depends on context (richness of the current job market). Learning contexts, therefore, is crucial for optimal decision-making. Humans demonstrate a bias when learning contexts; we learn faster about improvements vs deteriorations. New techniques allow us to cleanly measure fast acting stress responses that might fluctuate with trial-by-trial learning. Using these new methods, we observe here that increased stress - specifically sympathetic (heart contractility) - might help overcome the learning bias (making us faster at learning contextual deterioration) and thereafter guide us toward better context appropriate decisions. For the first time we show that specific building blocks of good decision-making might benefit from short bursts of specific inputs of the stress system.

physiology↗

bioRxiv2018

The neural basis of hand choice: An fMRI investigation of the Posterior Parietal Interhemispheric Competition model.

The current study investigates a new neurobiological model of human hand choice: The Posterior Parietal Interhemispheric Competition (PPIC) model. The model specifies that neural populations in bilateral posterior intraparietal and superior parietal cortex (pIP-SPC) encode actions in hand-specific terms, and compete for selection across and within hemispheres. Actions with both hands are encoded bilaterally, but the contralateral hand is overrepresented. We use a novel fMRI paradigm to test the PPIC model. Participants reach to visible targets while in the scanner, and conditions involving free choice of which hand to use (Choice) are compared with when hand-use is instructed. Consistent with the PPIC model, bilateral pIP-SPC is preferentially responsive for the Choice condition, and for actions made with the contralateral hand. In the right pIP-SPC, these effects include anterior intraparietal and superior parieto-occipital cortex. Left dorsal premotor cortex, and an area in the right lateral occipitotemporal cortex show the same response pattern, while the left inferior parietal lobule is preferentially responsive for the Choice condition and when using the ipsilateral hand. Behaviourally, hand choice is biased by target location - for targets near the left/right edges of the display, the hand in ipsilateral hemispace is favoured. Moreover, consistent with a competitive process, response times are prolonged for choices to more ambiguous targets, where hand choice is relatively unbiased, and fMRI responses in bilateral pIP-SPC parallel this pattern. Our data provide support for the PPIC model, and reveal a selective network of brain areas involved in free hand choice, including bilateral posterior parietal cortex, left-lateralized inferior parietal and dorsal premotor cortices, and the right lateral occipitotemporal cortex.

neuroscience↗