Optogenetics publications

Everyday decisions depend on associations between sensory stimuli, actions, and outcomes. The striatum supports these sensorimotor associations through dopamine-dependent plasticity. Recent work has characterized a local striatal microcircuit in which cholinergic interneurons (CINs) modulate dopamine release via activation of nicotinic receptors on dopamine axons. Here, we show that visual stimuli evoke dopamine in the dorsomedial striatum partly through this cholinergic mechanism. Using anatomical and functional methods to identify the pathways involved, we found that visual and auditory cortices lack connectivity with CINs and were unable to drive cholinergic-dependent dopamine release. Frontal regions, which were activated by visual stimuli, strongly recruited CINs, producing robust dopamine release both ex vivo and in vivo. These findings reveal a fundamental distinction between sensory and frontal corticostriatal inputs, demonstrating that only the latter can evoke cholinergic-dependent dopamine signals. This work establishes a framework for understanding how cortical circuits shape striatal dopamine to support reinforcement learning.

Hippocampus, a key hub of neural circuits for spatial learning and memory, has attracted tremendous studies. Neuronal information processing in the hippocampus can be regulated by many types of neuropeptides. Cholecystokinin ( Cck ), the most abundant neuropeptide in the central nervous system that is involved in modulating neuronal functions, such as cognition, memory, and neuroplasticity, is widely expressed in the hippocampus. However, whether local excitatory Cck neurons modulate hippocampal function is still unclear. In this study, we showed that CA1 pyramidal neurons receive projections from excitatory Cck neurons in area CA3 (CA3 Cck neurons) in adult mice. Subsequently, activation of the CA1-projecting CA3 Cck neurons triggers the release of Cck . Then, we found that the activity of CA3 Cck -CA1 neurons supports the hippocampal-dependent tasks. Furthermore, inhibition of CA3 Cck -CA1 projections or knockdown of CA3 Cck gene expression markedly impaired the behavioral tasks and neuroplasticity. Taken together, these results may add to a better understanding of how neuromodulators regulate the neural functions in the central nervous system.

Dopamine contributes to reward-related decision making, but its contributions to decision contexts that include explicit punishment are less well understood. To elucidate the role of ventral tegmental area (VTA) dopamine neurons in decision making under risk of punishment, we used fiber photometry to record activity in these neurons during a decision-making task in which rats choose between a small, “safe” reward and a large reward associated with varying probabilities of explicit punishment. Dopamine neuron activity exhibited phasic increases during risky “Wins” (reward without punishment) and phasic decreases during risky “Losses” (reward plus punishment), each of which scaled with punishment probability and intensity. Further analyses revealed that this outcome-evoked activity predicted choices on subsequent trials. To determine whether VTA dopamine neuron activity plays a causal role in these risk-based decisions, we used optogenetics to selectively inhibit these neurons during risky Wins and Losses. Inhibition of VTA dopamine neurons during Wins selectively reduced the frequency of risky choices after a Win, whereas inhibition during Losses selectively reduced the frequency of risky choices after a Loss. These data reveal that VTA dopamine neuron activity during outcome receipt is causally related to subsequent decision-making behavior. In addition, the fact that the effects of inhibition on choice behavior were specific to the outcome with which the inhibition was paired suggests that VTA dopamine neuron activity contributes to updating after Wins and Losses independently. Significance Statement Dopamine is implicated in movement, motivation, and learning, and has been strongly linked with substance use and risk-seeking behavior. Despite these associations, it is unclear how the activity of dopamine neurons influences decision making under risk of punishment. To elucidate this, we recorded from ventral tegmental area (VTA) dopamine neurons and found that their activity at the population level integrates reward alongside the probability and intensity of punishment experienced during risky outcomes. Further, inhibition of VTA dopamine neuron activity during risky outcomes decreased risk-seeking behavior in an outcome-specific manner. Our findings align with models suggesting that VTA dopamine neurons signal prediction errors, and provide insight into the role of these neurons in adaptive decision making.

Background/Objectives: Dopamine is well known for its role in reward learning, where phasic activity encodes prediction errors and supports the formation of cue–outcome associations. More recently, dopamine has been implicated in encoding salience, novelty, and aversive events, suggesting a broader function in shaping learning and memory across motivational contexts. However, how accumbal dopamine contributes to the recovery of extinguished fear, a process central to relapse in anxiety and trauma-related disorders, remains unclear. Methods: Here, we examined NAc core dopamine dynamics during shock-induced reinstatement of an extinguished fear memory. Using dLight fiber photometry, we found that a sustained decrease in baseline dopamine marked extinction recall. In contrast, an unexpected reminder footshock prevented this reduction, maintaining dopamine levels near baseline as freezing behavior re-emerged. Results: The reminder shock also evoked a transient dopamine peak, and optogenetic manipulations demonstrated that dopamine signaling during this period bidirectionally modulated reinstatement, with enhancement of dopamine release increasing reinstatement and inhibition of dopamine terminals markedly attenuating it. Together, these results demonstrate that unexpected aversive events reset NAc core dopamine levels and gate the return of extinguished fear. Conclusions: By revealing that accumbal dopamine contributes to fear recovery, this work broadens current models of dopamine function and identifies a neural mechanism through which surprising events may promote relapse of aversive memories in anxiety- and stress-related disorders.

Addicted individuals prefer drug rewards over natural rewards. Dysregulated dopamine (DA) signaling in the nucleus accumbens is thought to trigger this phenomenon, but there is little supporting evidence. Using a genetically encoded sensor, we monitored DA dynamics in mice in an operant associative task with natural (fat solution) or artificial (cocaine or optogenetic DA self-stimulation) rewards. During learning, DA transients emerged at predictive cues for both reward types, vanished at natural reward delivery, but persisted at artificial reward delivery. In choice sessions, animals’ preferences varied from exclusive natural reward to exclusive artificial reward. Individual preferences were predicted by cue-evoked DA response magnitudes. Revaluation of reward contingencies shifted reward-type preference and DA signaling accordingly, but not in mice showing compulsive drug seeking, indicating impaired value updating in these mice. These results support a model in which DA drives adaptive reward seeking, with persistent cue-associated DA signaling underpinning addiction vulnerability.

The basolateral amygdala (BLA) is important for assigning emotional weight to environmental stimuli to guide learning, discrimination, and adaptive vigilance. The contribution of neuromodulator inputs such as dopamine to this process is unclear. Here, we recorded in vivo BLA dopamine signals across emotional learning paradigms. We show that BLA dopamine scales with a stimulus's emotional intensity, but not value or associative strength, and reward-predictive cues evoke BLA dopamine signals that diminish, rather than grow, with training. In a complex learning context, where rats discriminated between multiple valenced associations, the magnitude of cue-evoked BLA dopamine re-scaled to report the level of relative emotional saliency. Threat and safety cues prompted larger, sustained dopamine signals compared to reward and neutral cues. Together, our data reveal a pattern of dopamine encoding with a unique contribution to learning, for dynamic disambiguation of affective states.

Adaptive behavior requires that behaviorally relevant signals gain access to neural circuits guiding action. The thalamus has long been proposed to regulate information flow to cortical and subcortical systems, yet whether it also tracks internally generated goal signals remains unclear. Here, we show that neurons in the paraventricular thalamus (PVT) projecting to the nucleus accumbens (NAc) encode the motivational value of safety during active avoidance. As mice learn to avoid threat, PVT→NAc neurons develop a signal that emerges selectively at successful avoidance, is experience-dependent, and diminishes following outcome devaluation. Selective silencing of the PVT→NAc pathway at safety onset reduces the motivational value assigned to safety without impairing action–outcome learning. Mechanistically, PVT input engages cholinergic interneurons (CIN) in the NAc to regulate dopamine release via synaptic potentiation mediated by GluA2-lacking AMPA receptors at PVT–CIN synapses. Disrupting this plasticity reduces the motivational impact of safety. These findings identify a thalamostriatal mechanism through which learned goals gain stable access to motivational circuitry.

Sensory experience refines neural circuits during critical periods of postnatal development 1–3 . Although neuronal activity is known to orchestrate the circuit wiring that underlies this process 4,5 , the environmental cues that restrain developmental plasticity as animals mature are less clear. Here we examine the experience-dependent maturation of the mouse primary visual cortex across postnatal development using paired single-cell transcriptomic and chromatin accessibility sequencing. In addition to identifying the activity-dependent gene programs that emerge within each cortical cell type, we find that light exposure drives astrocyte maturation through cell-type-specific recruitment of the glucocorticoid receptor (encoded by Nr3c1 ) to chromatin. Astrocyte glucocorticoid receptor signalling activates an extensive gene regulatory program that is partially conserved in human brain development and promotes maturation processes that may regulate critical period closure. Collectively, these findings reveal that astrocyte glucocorticoid receptor signalling restricts neuronal plasticity. Glucocorticoid regulation of astrocyte maturation may also contribute to the effects of early-life stress across the brain, and the disruption of this process may increase susceptibility to neuropsychiatric disease.

Dysregulation of metabotropic glutamate receptor 5 (mGluR5) and cholecystokinin (CCK) signaling has been implicated in major depressive disorder (MDD), but the underlying circuit mechanisms remain unclear. Here, we define how mGluR5 regulates depressive‐like behaviors through CCK signaling in the entorhinal cortex (EC) to basolateral amygdala (BLA) pathway. Anatomical tracing and optogenetics show that CCK‐expressing neurons in the EC project to the BLA and that their activation increases glutamatergic activity in this region. Bidirectional circuit manipulation establishes causality: optogenetic stimulation induces, whereas inhibition alleviates, depressive‐like phenotypes. Expansion microscopy reveals postsynaptic mGluR5 enrichment along this pathway. Chronic social defeat stress (CSDS) downregulates mGluR5 in the BLA. Pharmacologically, mGluR5 antagonism phenocopies CCK‐driven pro‐depressive effects, whereas CCK knockout mice resist behavioral consequences of mGluR5 inhibition. Mechanistically, mGluR5 agonism suppresses CCK release, disrupts BLA long‐term potentiation, and mitigates CSDS‐induced behaviors. Circuit‐specific mGluR5 knockdown in the EC CCK →BLA pathway increases stress susceptibility. These findings identify an mGluR5‐CCK axis within an EC CCK →BLA circuit that governs stress‐induced affective states.

Salivation supports oral health, taste sensation, swallowing, and digestion, but the brain mechanisms that regulate this process remain largely unknown. Here, we identify a salivatory center in the mouse brain stem that integrates sensory and learned anticipatory signals to control salivation. We show that activating choline acetyltransferase-expressing neurons in the inferior salivatory nucleus (IS) is sufficient to trigger saliva secretion. Using fiber photometry, we monitor real-time IS neural responses to mechanosensory and gustatory stimulation and find tight correlation with salivatory output. We further demonstrate that IS neurons receive input from local brain stem circuits, mediating rapid hardwired responses to taste, as well as direct cortical projections. Notably, gustatory cortex input is required for salivatory responses to predictive sensory cues in a Pavlovian conditioning paradigm. Together, our findings define the circuit underlying taste-evoked and anticipatory salivation and provide a foundation for dissecting this autonomic response in health and disease.

Serotonin (5-hydroxytryptamine; 5HT) has long been considered anti-aggressive, but the mechanisms by which 5HT regulates downstream circuits to control aggression remain unclear. Combining fiber photometry, optogenetics, and miniaturized microscope recordings in double-transgenic male mice, we find that 5HT levels ramp up in the nucleus accumbens during aggression, inhibiting a subset of D1 medium spiny neurons to suppress attacks. Our results reveal a novel 5HT-mediated neuromodulatory mechanism for limiting aggressive behavior.

Brain systems mediating responses to previously encountered threats provide critical survival functions. Fear memory and extinction are underpinned by neural representations in the basolateral amygdala (BLA) 1–7 , but the contribution of non-neuronal cells, including astrocytes, to these processes remains unresolved. Here, using in vivo calcium (Ca 2+ ) imaging and causal astrocyte manipulations, we find that BLA astrocytes dynamically track fear state and support fear memory retrieval and extinction. By combining astrocyte manipulations with in vivo BLA neuronal Ca 2+ imaging and electrophysiological recordings, we show that astrocyte Ca 2+ signalling enables neuronal encoding of fear memory retrieval and extinction, and readout through a BLA–prefrontal circuit. Our findings reveal a key role for astrocytes in the generation and adaptation of fear-state-related neural representations, revising neurocentric models of critical amygdala-mediated adaptive functions.

The entorhinal-hippocampal system constitutes a pivotal neural circuit in the central nervous system. It is critically involved in processing spatial learning and memory. However, the specific neural interactions between entorhinal inputs and intra-hippocampal subcircuits that underlie spatial coding remain elusive. To address this gap, we integrated multimodal approaches including in vivo calcium imaging, dual-color optogenetic manipulation, chemogenetic intervention, electrophysiological recordings, immunohistochemistry, and Morris water maze (MWM) behavior to dissect how entorhinal-hippocampal afferents modulate hippocampal computations. Intriguingly, CA1-projecting CA3 neurons exhibited pronounced hyperactivity during early spatial learning, with activity gradually declining after sustained task performance. Chemogenetic inactivation of medial entorhinal-hippocampal afferents attenuated both neural responses of CA1-projecting CA3 neurons and the performance of spatial learning, hinting that medial entorhinal cortex (MEC) inputs to the hippocampus are essential for animals to execute spatial tasks precisely. By implementing dual-light theta-burst stimulation to co-activate ChrimsonR-expressing CA3-CA1 afferents and Chronos-expressing MEC-CA1 terminals, we observed robust heterosynaptic long-term potentiation in the dorsal CA1 region in vitro brain slice. This neuroplasticity was mediated synergistically by activating both NMDA receptors and voltage-gated calcium channels. Our findings establish that entorhinohippocampal afferents exert multilevel regulatory control over hippocampal function, thereby advancing mechanistic understanding of memory-related neurological pathologies.

The mammillary body (MB) has traditionally been regarded as a relay station for the hippocampus and plays a pivotal role in the Papez circuit. However, its molecular and cellular organization remains inadequately characterized. This study focuses on the horizontally symmetrically distributed neurotensin (Nts)-expressing and nitric oxide synthase 1 (Nos1)-expressing neurons in the MB, demonstrating that Grik4 (encoding a high-affinity kainate receptor subunit) underlies their distinct electrophysiological properties. Within neural circuits, Nts and Nos1 neurons receive excitatory inputs from the ventral subiculum and send parallel excitatory projections to the dorsomedial and ventrolateral subdivisions of the anteroventral thalamus (AV). These 2 cell type-specific circuits are essential for working memory and exhibit selective activation during the maintenance phase with a marked temporal difference. Together, our findings establish a direct link from molecular identity to circuit architecture and cognitive processing by demonstrating that molecularly distinct Nts and Nos1 neurons constitute differential circuits with convergent inputs, divergent outputs, and dissociable roles in working memory maintenance. This work thus reveals a fundamental cross-scale organizational principle—molecule, cell, circuit, function—within the MB.

Maternal obesity predisposes offspring to metabolic diseases. Here, we show that non-nutritive sensory components of a high-fat diet (HFD), beyond its hypercaloric, obesogenic effects, are sufficient to alter metabolic health in the offspring. To dissociate the caloric and sensory components of HFD, we fed dams a bacon-flavoured diet, isonutritional to a normal chow diet but enriched with fat-related odours. Offspring exposed to these fat-related odours during development display metabolic inflexibility and increased adiposity when fed HFD in adulthood independently of maternal metabolic health. Developmental exposure to fat-related odours shifts mesolimbic dopaminergic circuits and Agouti-related peptide (AgRP) hunger neurons’ responses to phenocopy those of obese mice, including a desensitization of AgRP neurons to dietary fat. While neither neonatal optogenetic activation of sensory circuits nor passive exposure to fat-related odours is sufficient to alter metabolic responses to HFD, coupling optogenetic stimulation of sensory circuits with caloric intake exacerbates obesity. Collectively, we report that fat-related sensory cues during development act as signals that can prime central responses to food cues and whole-body metabolism regulation.

The anterior-lateral motor cortex (ALM) has been extensively studied as a model for understanding the cortical mechanisms involved in planning directional movements. ALM neurons show preparatory activity that predict whether the mouse will produce a left- or right-directed lick. While the neural mechanisms underlying ALM dynamics and their links to behavior are beginning to be elucidated, the sources of this directional activity remain unclear. Here, we examined the role of ALM dopaminergic circuits in mice performing a directional licking task. We report that dopamine (DA) signals and the activity of neurons expressing D1 receptors (D1R + ) tracked the preparation and execution of licking and demonstrated a bias for planning of licks aimed at the direction contralateral to the recording site. Unilateral optogenetic manipulations of D1R + neurons or DA afferents affected lateral licking in a way consistent with their role in planning contralateral movements. Together, these results show that cortical DA modulation plays an important role in the motor preparation of directional movements.

The ventral tegmental area (VTA) is classically linked to learning and reinforcement via the actions of dopamine neurons. Intermingled VTA GABA neurons are positioned to regulate dopamine, but we lack detailed insight into how this population contributes to behavior. Recording calcium activity in VTA dopamine and GABA neurons, we show that, while dopamine neurons were only responsive to appetitive events, GABA neurons actively encoded both appetitive and aversive stimuli. Critically, GABA neuron activity selectively integrated events when both valences were present. In a motivational conflict task, where rats weighed decisions to avoid shock or seek reward, GABA neuron activity scaled with escalating cost and predicted reward seeking. Optogenetic inhibition of GABA neurons disrupted reward seeking specifically under conditions of motivational conflict. Together, our data show that VTA GABA neurons reflect a broader learning signal, compared to dopamine neurons, that is important for directing economic decision making in complex, multivalent environments.

A central mechanism of exposure-based cognitive behavioral therapy for anxiety and trauma-related disorders is fear extinction. However, the mechanisms underlying fear extinction are deficient in some individuals, leading to treatment resistance. Recent animal studies demonstrate that upon omission of the aversive, unconditioned stimulus (US) during fear extinction, dopamine (DA) neurons in the ventral tegmental area (VTA) produce a prediction error (PE)-like signal. However, whether this VTA-DA neuronal PE-like signal is altered in animals exhibiting deficient fear extinction has not been studied. Here, we used a mouse model of impaired fear extinction [129S1/SvImJ (S1) inbred mouse strain] to monitor and manipulate VTA-DA neurons during extinction. Male DAT-Cre mice backcrossed onto an S1 background (S1-DAT-Cre) exhibited impaired extinction but normal VTA-DA neuron number, as compared with BL6-DAT-Cre mice. In vivo fiber photometry showed that impaired extinction in male S1-DAT-Cre mice was associated with abnormally sustained US omission-related VTA-DA neuronal calcium activity during extinction training and retrieval. Neither in vivo optogenetic photoexcitation of VTA-DA neuronal cell bodies nor their axons in the infralimbic cortex was sufficient to rescue deficient extinction in male S1-DAT-Cre mice, at least within the optogenetic and behavioral parameters used. These data suggest that alterations in the activity of VTA-DA neurons during extinction learning and retrieval may be associated with deficient fear extinction in male S1 mice and could potentially contribute to extinction impairments in patient populations.

Long-term sustained pain following acute physical injury is a prominent feature of chronic pain conditions1. Populations of neurons that rapidly respond to noxious stimuli or tissue damage have been identified in the spinal cord and several nuclei in the brain2-4. Understanding the central mechanisms that signal ongoing sustained pain, including after tissue healing, remains a challenge5. Here we use spatial transcriptomics, neural manipulations, activity recordings and computational modelling to demonstrate that activity in an ensemble of anatomically and molecularly diverse parabrachial neurons that express the neuropeptide Y (NPY) receptor Y1 (Y1R neurons) is increased following injury and predicts functional coping behaviour. Hunger, thirst or predator cues suppressed sustained pain, regardless of the injury type, by inhibiting parabrachial Y1R neurons via the release of NPY. Together, our results demonstrate an endogenous analgesic hub at pain-responsive parabrachial Y1R neurons.