Biology subjects

Kaiser, L. F.

Publications and source records attributed to Kaiser, L. F..

4 recordsLinked to original sources

bioRxiv2024

Patch-leaving decisions and pupil-linked arousal systems

Deciding when to abandon a depleting resource in favour of potentially richer alternatives is fundamental to adaptive behaviour. Such patch-leaving decisions require balancing the expected advantage of leaving against both the cost of moving and the reward foregone in the current environment. Previous research suggests that activity of noradrenergic (NE) neurons in the locus coeruleus (LC) underpins patch-leaving. In the current study, we used pupil dilation as a time-resolved readout of subcortical neuromodulation during patch-leaving. We hypothesised that leave decisions will be preceded by a transient pupil dilation. Participants harvested from exponentially depleting patches (blueberry bushes) with three initial reward values, in two environments, which differed in the variability of initial reward values. Behavioural results show that, as predicted by the mathematically optimal solution, participants adjusted their decisions based on the instantaneous reward rate, but also displayed a bias to overharvest (stay longer in compared to the optimum), which was more pronounced in the high variability environment. Pupil size was overall larger in the high variability environment, associated with increased uncertainty. Importantly, we observed an increased transient pupil dilation in response to reward outcomes immediately preceding leave compared to stay decisions, as well as an increase in pupil dilation (and RT) across successive stay trials, leading up to leave decisions, presumably indicating an increased LC-NE activity associated with abandoning current options to explore alternatives.

neuroscience↗

bioRxiv2024

Bidirectional modulation of reward-guided decision making by dopamine

RationaleThe neuromodulator dopamine is known to play a key role in reward-guided decision making, where choice options are often characterized by multiple attributes. Different decision strategies can be used to merge these choice attributes with personal preferences (e.g., risk preferences) and integrate them into a single subjective value. While the influence of dopamine on risk preferences has been investigated, it is unknown whether dopamine is also involved in arbitrating between decision strategies. ObjectiveIn the present study, we investigate the effects of pharmacological dopamine manipulations on arbitrating between different decision strategies in a healthy sample. Methods31 healthy male participants performed a reward-guided decision-making task under the influence of the dopamine D2/D3-receptor antagonist amisulpride (400 mg), the dopamine precursor L-DOPA (100 mg L-DOPA + 25 mg cardidopa), or placebo in a double-blind within-subject design. The effect of dopamine on reward-guided decisions and decision strategies was analyzed using hierarchical implementations of regressions and Bayesian models. ResultsNotably, we observed that the dopaminergic interventions shifted the (overall) weighting of option attributes without changing how option attributes are integrated into a subjective value (decision strategy). These effects were bidirectional: Amisulpride reduced whereas L-DOPA increased the degree to which choices were influenced by both reward magnitude and reward probability. These effects occurred in the absence of changes in statistically optimal behavior. ConclusionTogether, our data provide evidence for a role of dopamine in controlling the influence of value parameters on choice irrespective of decision strategies.

neuroscience↗

bioRxiv2019

Dissociable roles of cortical excitation-inhibition balance during patch-leaving versus value-guided decisions

In a dynamic world, it is essential to decide when to leave an exploited resource. Such patch-leaving decisions involve balancing the cost of moving against the gain expected from the alternative patch. This is in contrast with value-guided decisions that typically involve maximizing reward by selecting the current best option. Patterns of neuronal activity pertaining to patch-leaving decisions have been reported in the dorsal anterior cingulate cortex (dACC), whereas competition via mutual inhibition in the ventromedial prefrontal cortex (vmPFC) is thought to underlie value-guided choice. Here, we show that the balance between cortical excitation and inhibition (E/I balance), measured by the ratio of GABA and glutamate concentrations, plays a dissociable role for the two kinds of decisions. Patch-leaving decision behaviour was related to E/I balance in dACC. In contrast, value-guided decision making was related to E/I balance in vmPFC. These results support previous mechanistic accounts of value-guided choice and provide novel evidence for a role of dACC E/I balance in patch-leaving decisions.

neuroscience↗

bioRxiv2019

Decisions bias future choices by modifying hippocampal associative memories

Decision making is guided by memories of option values. However, retrieving items from memory renders them malleable. Here, we show that merely retrieving values from memory and making a choice between options is sufficient both to induce changes to stimulus-reward associations in the hippocampus and to bias future decision making. After allowing participants to make repeated choices between reward-conditioned stimuli, in the absence of any outcome, we observed that participants preferred stimuli they had previously chosen, and neglected previously unchosen stimuli, over otherwise identical-valued options. Using functional brain imaging, we show that decisions induced changes to hippocampal representations of stimulus-outcome associations. These changes were correlated with future decision biases. Our results indicate that choice-induced preference changes are partially driven by choice-induced modification of memory representations and suggest that merely making a choice - even without experiencing any outcomes - induces associative plasticity.

neuroscience↗