Biology subjects

Wallace, J. B.

Publications and source records attributed to Wallace, J. B..

3 recordsLinked to original sources

bioRxiv2026

A paradigm for skilled forelimb reaching by head-restrained mice

Forelimb reaching tasks are widely used in neuroscience across species. In mice, pellet reaching is especially useful because it requires fine motor control. However, few automated pellet-delivery systems are well suited for head-restrained reaching, where pellet position must be highly consistent. Here we present a complete pipeline for head-restrained, or head-fixed, forelimb reaching in mice. The pipeline includes a simple customizable pellet-presentation rig, an effective training protocol, and analysis code to detect reaches and classify their outcomes. To demonstrate pipeline utility, we quantified interruption of an ongoing reach. The temporal requirement for initiating cancellation was dependent on the phase of the reach, lengthening significantly as the reach neared completion. These results show that the pipeline can resolve fine phase-dependent features of skilled behavior and provide a practical framework for studying motor control in head-restrained mice.

neuroscience↗

bioRxiv2024

Hunger modulates exploration through suppression of dopamine signaling in the tail of striatum

Caloric depletion leads to behavioral changes that help an animal find food and restore its homeostatic balance. Hunger increases exploration and risk-taking behavior, allowing an animal to forage for food despite risks; however, the neural circuitry underlying this change is unknown. Here, we characterize how hunger restructures an animals spontaneous behavior as well as its directed exploration of a novel object. We show that hunger-induced changes in exploration are accompanied by and result from modulation of dopamine signaling in the tail of the striatum (TOS). Dopamine signaling in the TOS is modulated by internal hunger state through the activity of agouti-related peptide (AgRP) neurons, putative "hunger neurons" in the arcuate nucleus of the hypothalamus. These AgRP neurons are poly-synaptically connected to TOS-projecting dopaminergic neurons through the lateral hypothalamus, the central amygdala, and the periaqueductal grey. We thus delineate a hypothalamic-midbrain circuit that coordinates changes in exploration behavior in the hungry state.

neuroscience↗

bioRxiv2024

Mixed representations of choice and outcome by GABA/glutamate cotransmitting neurons in the entopeduncular nucleus

The basal ganglia (BG) are an evolutionarily conserved and phylogenetically old set of sub-cortical nuclei that guide action selection, evaluation, and reinforcement. The entopeduncular nucleus (EP) is a major BG output nucleus that contains a population of GABA/glutamate cotransmitting neurons (EPSst+) that specifically target the lateral habenula (LHb) and whose function in behavior remains mysterious. Here we use a probabilistic switching task that requires an animal to maintain flexible relationships between action selection and evaluation to examine when and how GABA/glutamate cotransmitting neurons contribute to behavior. We find that EPSst+neurons are strongly engaged during this task and show bidirectional changes in activity during the choice and outcome periods of a trial. We then tested the effects of either permanently blocking cotransmission or modifying the GABA/glutamate ratio on behavior in well-trained animals. Neither manipulation produced detectable changes in behavior despite significant changes in synaptic transmission in the LHb, demonstrating that the outputs of these neurons are not required for on-going action-outcome updating in a probabilistic switching task.

neuroscience↗