Biology subjects

Apps, M. A. J.

Publications and source records attributed to Apps, M. A. J..

5 recordsLinked to original sources

bioRxiv2025

Neural signatures of harm aversion predict later willingness to exert effort for others rewards

Prosocial behaviours--actions that incur personal costs to benefit others--are central to human social life. Two key domains are moral harm aversion, where individuals forgo personal gains to prevent harming others, and prosocial effort, which involves exerting effort to benefit others. Although previous studies suggest a relationship between these behaviours, it remains unclear whether neural responses in one domain can predict prosocial motivation in another. Here, we tested whether neural sensitivity to morally salient information in harm aversion could predict prosocial effort later. Participants completed two tasks: a harm aversion task during fMRI, in which they traded off monetary profit against delivering electric shocks to another person; and, one week later, a prosocial effort task outside the scanner, in which they decided whether rewards for others were worth the required physical effort. We focused on three regions implicated in cost-benefit decision-making and social cognition: the anterior cingulate cortex (ACC), anterior insula (AI), and temporoparietal junction (TPJ). Behaviourally, greater harm aversion was associated with increased prosocial effort. Neurally, AI responses to others harm predicted sensitivity to others rewards in the effort task, consistent with a role in representing others outcomes across positive and negative valences. By contrast, TPJ responses to profit from harming others predicted decreased sensitivity to others rewards, suggesting a role in context-dependent valuation that may constrain prosocial behaviour. These findings demonstrate that neural responses to morally salient information in one context correlate with prosocial motivation in another, highlighting mechanisms that bridge moral sensitivity and effortful prosociality.

neuroscience↗

bioRxiv2024

Functional Magnetic Resonance Spectroscopy of Prolonged Motor Activation using Conventional and Spectral GLM Analyses

BackgroundFunctional MRS (fMRS) is a technique used to measure metabolic changes in response to increased neuronal activity, providing unique insights into neurotransmitter dynamics and neuroenergetics. In this study we investigate the response of lactate and glutamate levels in the motor cortex during a sustained motor task using conventional spectral fitting and explore the use of a novel analysis approach based on the application of linear modelling directly to the spectro-temporal fMRS data. MethodsfMRS data were acquired at a field strength of 3 Tesla from 23 healthy participants using a short echo-time (28ms) semi-LASER sequence. The functional task involved rhythmic hand clenching over a duration of 8 minutes and standard MRS preprocessing steps, including frequency and phase alignment, were employed. Both conventional spectral fitting and direct linear modelling were applied, and results from participant-averaged spectra and metabolite-averaged individual analyses were compared. ResultsWe observed a 20% increase in lactate in response to the motor task, consistent with findings at higher magnetic field strengths. However, statistical testing showed some variability between the two averaging schemes and fitting algorithms. While lactate changes were supported by the direct spectral modelling approach, smaller increases in glutamate (2%) were inconsistent. Exploratory spectral modelling identified a 4% decrease in aspartate, aligning with conventional fitting and observations from prolonged visual stimulation. ConclusionWe demonstrate that lactate dynamics in response to a prolonged motor task are observed using short-echo time semi-LASER at 3 Tesla, and that direct linear modelling of fMRS data is a useful complement to conventional analysis. Future work includes mitigating spectral confounds, such as scalp lipid contamination and lineshape drift, and further validation of our novel direct linear modelling approach through experimental and simulated datasets.

neuroscience↗

bioRxiv2024

Neural and computational mechanisms of effort under the pressure of a deadline

Deadlines fundamentally shape the motivation for effort. Research examining effort-based choices finds high effort is an avoided cost. However, this work overlooks the fact that effort can be valuable when it makes progress on long-term goals before deadlines. We test a new framework where motivation depends on deadline pressure (work remaining / time remaining). Across three studies we use computational modelling on novel tasks examining effort-based decisions when effort makes progress on goals with deadlines. In support of hypotheses, deadline pressure significantly impacts decision-making, shifting people from avoiding effort, to seeking and valuing it. Using ultra-high-field fMRI, we show that functionally connected putamen and midcingulate cortex (MCC) sub-regions process and update estimates of deadline pressure, with distinct anterior cingulate and putamen sub-regions processing the costs or added value of effort. We show the neurocomputational mechanisms for how deadline pressure shapes motivation, and that keep us on track for our goals.

neuroscience↗

bioRxiv2023

Beta and theta oscillations track effort and previous reward in human basal ganglia and prefrontal cortex during decision making

Choosing whether to exert effort to obtain rewards is fundamental to human motivated behavior. However, the neural dynamics underlying the evaluation of reward and effort in humans is poorly understood. Here, we investigate this with chronic intracranial recordings from prefrontal cortex (PFC) and basal ganglia (BG; subthalamic nuclei and globus pallidus) in people with Parkinsons disease performing a decision-making task with offers that varied in levels of reward and physical effort required. This revealed dissociable neural signatures of reward and effort, with BG beta (12-20 Hz) oscillations tracking subjective effort on a single trial basis and PFC theta (4-7 Hz) signaling previous trial reward. Stimulation of PFC increased overall acceptance of offers in addition to increasing the impact of reward on choices. This work uncovers oscillatory mechanisms that guide fundamental decisions to exert effort for reward across BG and PFC, as well as supporting a causal role of PFC for such choices.

neuroscience↗

bioRxiv2022

Neural representations of vicarious rewards are linked to interoception and prosocial behaviour

Every day we constantly observe other people receiving rewards. Theoretical accounts posit that vicarious reward processing might be linked to peoples sensitivity to internal body states (interoception) and facilitates a tendency to act prosocially. However, the neural processes underlying the links between vicarious reward processing, interoception and prosocial behaviour are poorly understood. Previous research has linked vicarious reward processing to the anterior cingulate gyrus (ACCg) and the anterior insula (AI). Can we predict someones propensity to be prosocial or to be aware of interoceptive signals from variability in how the ACCg and AI process rewards? Here, participants monitored rewards being delivered to themselves or a stranger during functional magnetic resonance imaging. Later, they performed a task measuring their willingness to exert effort to obtain rewards for others, and a task measuring their propensity to be aware and use interoceptive signals. Using multivariate similarity analysis, we show that peoples willingness to be prosocial is predicted by greater similarity between self and other representations in the ACCg. Moreover, greater dissimilarity in self-other representations in the AI is linked to interoceptive propensity. These findings highlight that vicarious reward is linked to bodily signals in AI, and foster prosocial tendencies through the ACCg.

neuroscience↗