Biology subjects

Roshgadol, J.

Publications and source records attributed to Roshgadol, J..

4 recordsLinked to original sources

bioRxiv2026

Cellular and molecular coding of habit-driven behavior in the dorsal raphe nucleus

Chronic stress has potent effects on reward-seeking behavior, reducing hedonic drive but also biasing individuals toward habitual responding at the expense of goal-directed action. While prior studies have implicated corticostriatal circuits in these shifts, the contribution of the dorsal raphe nucleus (DRN) - a central neuromodulatory hub that regulates motivational states - remains poorly understood. Here, we identify a key role for DRN neurons in mediating stress-induced transitions from goal-directed to habit-driven behavior. Using two-photon calcium imaging in awake behaving mice, we show that DRN neurons encode representations of both effort expenditures and reward acquisition that are integrated at the single-neuron level. Chronic stress selectively enhances reward-related responses in habit-driven individuals, and deficits in reward-related activity in DRN neurons predict future habit formation after chronic stress. Single-nucleus transcriptional profiling revealed that chronic stress drives habit-related gene expression changes in GABAergic DRN neurons, including upregulation of genes implicated in synapse function and inhibitory signaling, and identified potential pharmacological treatment targets. Optogenetic inhibition of DRN GABA neurons rescued stress effects on habit formation, driving stable shifts in operant responding that persisted for days. Together, these findings establish the DRN as a critical modulator of stress-induced behavioral inflexibility, and identify a new role for DRN GABAergic neurons in determining stress susceptibility and driving stable and persistent switches in operant responding during recovery from chronic stress.

neuroscience↗

bioRxiv2026

Stress-induced motivational impairment is marked by diminished frontocortical cellular communication and neuropeptide signaling

BackgroundRepeated stress is a risk factor for developing motivational deficits which are common across a variety of disease states including depression and are particularly resistant to treatment with conventional pharmacotherapies. Amotivation is multifaceted and can be caused by impairments in value learning, reward anticipation, and cost-benefit decision-making. Importantly, not all individuals who experience chronic stress develop motivational symptoms, suggesting there may be neurobiological signatures of resilience. MethodsWe developed a novel head-restrained effortful reinforcement task in which anticipatory and consummatory behavior can be tracked. Chronic non-discriminatory social defeat stress combined with behavioral analysis and spatially resolved RNA sequencing were used to determine the transcriptional signatures of stress in the anterior cingulate cortex of mice with varying levels of motivational impairment as well as unstressed controls. ResultsWhile stress led to a general impairment in effortful reward seeking, animals differed in the extent of behavioral deficit, with increased susceptibility marked by a unique set of differentially expressed genes within the anterior cingulate cortex (ACC). By leveraging the spatial component of our data, we were further able to identify altered interactions from inhibitory neurons and astrocytes to excitatory pyramidal cells, which correlated with intact or impaired motivated responding following stress exposure. ConclusionsChronic psychosocial stress results in divergent effects on motivated behavior and distinct ACC transcriptional signatures that are concentrated in excitatory pyramidal neurons. Cell interaction analysis implicates enhanced inhibitory neuropeptide signaling and reduced astrocytic contact signaling as upstream markers of motivational resilience and point toward ACC hyperexcitability as a targetable feature of stress susceptibility.

neuroscience↗

bioRxiv2024

Dietary protein restriction diminishes sucrose reward and reduces sucrose-evoked mesolimbic dopamine signaling

ObjectiveA growing literature suggests manipulating dietary protein status decreases sweet consumption in rodents and in humans. Underlying neurocircuit mechanisms have not yet been determined, but previous work points towards hedonic rather than homeostatic pathways. Here we hypothesized that a history of protein restriction reduces sucrose seeking by altering mesolimbic dopamine signaling. MethodsWe tested this hypothesis using established behavioral tests of palatability and motivation, including the palatability contrast and conditioned place preference (CPP) tests. We used modern optical sensors for measuring real-time nucleus accumbens (NAc) dopamine dynamics during sucrose consumption, via fiber photometry, in male C57/Bl6J mice maintained on low-protein high-carbohydrate (LPHC) or control (CON) diet for [~]5 weeks. ResultsA history of protein restriction decreased the consumption of a sucrose dessert in sated mice by [~]50% compared to controls [T-test, p< 0.05]. The dopamine release in NAc during sucrose consumption was reduced, also by [~]50%, in LPHC-fed mice compared to CON [T-test, p< 0.01]. Furthermore, LPHC-feeding blocked the sucrose-conditioned place preference we observed in CON-fed mice [paired T-test, p< 0.05], indicating reduced motivation. This was accompanied by a 33% decrease in neuronal activation of the NAc core, as measured by c-Fos immunolabeling from brains collected directly after the CPP test. ConclusionsDespite ongoing efforts to promote healthier dietary habits, adherence to recommendations aimed at reducing the intake of added sugars and processed sweets remains challenging. This study highlights chronic dietary protein restriction as a nutritional intervention that suppresses the motivation for sucrose intake, via blunted sucrose-evoke dopamine release in NAc.

physiology↗

bioRxiv2022

Phasic locus coeruleus activity facilitates hippocampus-dependent trace fear memory formation

Locus coeruleus (LC) projections to the hippocampus play a critical role in learning and memory. However, the precise timing of LC-hippocampus communication during learning and which LC-derived neurotransmitters are important for memory formation in the hippocampus are currently unknown. Although the LC is typically thought to modulate neural activity via the release of norepinephrine, several recent studies have suggested that it may also release dopamine into the hippocampus and other cortical regions. In some cases, it appears that dopamine release from LC into the hippocampus may be more important for memory than norepinephrine. Here, we extend these data by characterizing the phasic responses of the LC and its projections to the dorsal hippocampus during trace fear conditioning. We find that the LC and its projections to the hippocampus respond to task-relevant stimuli and that amplifying these responses with optogenetic stimulation can enhance long-term memory formation. We also demonstrate that LC activity increases both norepinephrine and dopamine content in the dorsal hippocampus and that the timing of hippocampal dopamine release during trace fear conditioning is similar to the timing of LC activity. Finally, we show that hippocampal dopamine is important for trace fear memory formation, while norepinephrine is not.

animal behavior and cognition↗