Optogenetics publications

Contextual encoding in the dorsal hippocampus (DHPC) may recruit hypothalamic feeding modules to calibrate eating across environments, but the mechanistic instantiation of cells and circuits that undergird these processes is limited. Single-cell transcriptomics and transsynaptic tracing of the dorsolateral septum (DLS) identified an evolutionarily conserved prodynorphin (Pdyn)-expressing subpopulation of somatostatin (Sst)-expressing inhibitory neurons that receives dense dorsal, but not ventral, hippocampal inputs. Circuit optogenetics, electrophysiology, and in vivo calcium imaging demonstrated that DLS(Pdyn) neurons inhibit GABAergic neurons of the lateral hypothalamic area (LHA), exhibit context-dependent neural responses to food rewards and aversive stimuli, and confer contextual and internal state-dependent calibration of feeding. Viral deletion of Pdyn in the DLS impaired context-dependent food reward consumption, suggesting a role for dynorphin/kappa opioid receptor signaling in these processes. Together, our findings highlight how ancient LHA feeding circuits integrate DHPC input through DLS(Pdyn) inhibitory neurons to link context with regulation of food consumption.

Through learning and memory, the cortex dynamically forms sensory associations to guide our behavior in an ever-changing environment. How memory-related brain regions, such as the medial-temporal lobe, influence sensory cortex to support this process remains unclear. Here, we used two-photon calcium imaging of axonal projections from the perirhinal (PRh) cortex to the auditory cortex during learning and generalization of an auditory discrimination task. PRh input in the auditory cortex increased during learning and influenced performance in a categorization task. Chemogenetically silencing PRh input selectively disrupted the activity of auditory cortex layer 2/3 pyramidal neurons, and PRh photoactivation drove behavior toward overgeneralization. These findings highlight PRh input as a key modulatory pathway that shapes cortical dynamics underlying auditory learning and memory-guided sensory perception.

The medial nucleus accumbens shell (medNAcSh) is a key regulator of hedonic feeding, controlling reward consumption through its projections to downstream structures. Recent studies showed that the primary cellular mediators of these effects are dopamine 1 receptor-positive striatal projection neurons (D1-SPNs). Specifically, D1-SPN activity gets inhibited during reward consumption, and such inhibition is necessary and sufficient to authorize consumption, independent of metabolic need. Anatomically, the medNAcSh spans 1–1.5 mm along the rostro-caudal axis in mice, and previous studies have reported functional gradients along this axis. For instance, pharmacological studies have suggested that rostral rather than caudal medNAcSh regulates appetitive behavior. However, the mechanisms underlying this topographical gradient remain unknown. Here, we hypothesized that D1-SPNs contribute to this gradient by regulating hedonic feeding via a specific hotspot in the rostral medNAcSh. Using calcium monitoring with fiber photometry in mice, we show that rostral medNAcSh D1-SPNs demonstrate inhibitory responses during reward consumption, while caudal D1-SPNs do not. Consistently, optogenetic stimulation of rostral D1-SPNs inhibits consumption, while stimulation of caudal D1-SPNs had minimal effects, confirming the existence of a functional rostro-caudal gradient. Importantly, we observed no differences between rostral and caudal D1-SPNs in their responses to aversive stimuli, suggesting that the D1-SPN gradient is specific to appetitive contexts. To investigate potential molecular correlates of this functional gradient, we leveraged open-source anatomy datasets and performed fluorescent in situ hybridization, identifying Stard5 and Peg10 as markers enriched in the rostral and caudal medNAcSh, respectively. Finally, we developed a novel Stard5-Flp driver line to selectively target the rostral hotspot and demonstrated that Stard5+ neurons recapitulate rostral D1-SPN activity patterns. Together, these findings establish a spatially confined rostral medNAcSh subregion as a critical regulator of reward consumption and introduce Stard5 as a molecular tool for its manipulation, offering new opportunities for intervention in dysregulated eating.

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.

Cognitive impairments are common in absence epilepsy, yet the neural basis of these deficits remains largely unknown. Communication between the thalamic reuniens nucleus and the prefrontal cortex is critical for flexible behavior. Here, we identify a disruption of this pathway in mice with absence epilepsy. This dysfunction leads to impaired cognitive flexibility and altered cortical inhibition, linking seizure-related thalamic activity to prefrontal network imbalance. Notably, targeted stimulation of the thalamic-prefrontal pathway alleviates both seizure occurrence and cognitive deficits. These findings reveal a shared circuit mechanism underlying epileptic and cognitive symptoms, pointing to new strategies for intervention.

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.

Subcortical structures like the locus coeruleus (LC) are well known to regulate pupil-linked autonomic arousal, while the role of cortical circuits in this process remains largely unclear. We designed a closed-loop optogenetic system to inactivate the anterior cingulate cortex (ACC) in real time during pupil dilations. ACC inactivation decreased the magnitude of spontaneous pupil events. In parallel, ACC population activity scaled with the magnitude of spontaneously occurring pupil dilations. In addition to modulating spontaneous arousal, ACC responses to salient sensory stimuli scaled with the size of evoked pupil dilations and ACC inactivation suppressed saliency-linked pupil events. Last, we show that LC norepinephrine neurons signal arousal faster than the ACC. However, unlike the ACC, LC responses did not scale with the magnitude of pupil dilations. Collectively, our experiments identify the ACC as a key cortical site for sustaining momentary increases in pupil-linked arousal.

Dopamine is essential for striatal function and learning. Striatal dopamine release can be triggered by dopamine cell firing, but also by coordinated cholinergic interneuron activity, which stimulates dopamine release via presynaptic nicotinic acetylcholine receptors on dopamine axons. While acetylcholine-dependent dopamine release is well-documented ex vivo and under artificial optogenetic stimulation in vivo , its role during natural behavior has remained unclear. One possible endogenous driver of acetylcholine-dependent dopamine release is thalamic input, which provides strong excitatory drive to cholinergic interneurons. To examine whether thalamic input provokes acetylcholine-dependent dopamine release during behavior, we performed simultaneous fiber photometry recordings of striatal dopamine (GRAB-rDA3m) and thalamic axon activity (gCaMP8m) in the dorsomedial (DMS) and dorsolateral striatum (DLS) of mice learning the accelerating rotarod, a striatal-dependent task that demands precise and effortful motor control. Recordings were obtained on- and off-task and across days of training to capture the full arc of learning. Dopamine transients in DMS, but not DLS, were frequently coupled to peaks in thalamic axon activity via an acetylcholine-dependent mechanism. The occurrence of these thalamic-evoked DMS dopamine transients depended on learning, task engagement, and the recent history of dopamine activity, but did not contribute to motor error signals. Together, these findings establish thalamic input as a physiological driver of acetylcholine-dependent dopamine release in DMS. Moreover, they reveal that striatal sensitivity to this local release mechanism is dynamically gated by dopaminergic history, providing a compelling framework for understanding how local and soma-triggered dopamine signals are coordinated to support learning.

Quickly adapting behavior to changing environments is key for survival. Brain dopamine signals reinforce actions that procure rewards and avoid adverse outcomes. However, the molecular mechanisms within the circuits that actuate these signals at subsecond timescales remain unexplored. We show that midbrain endocannabinoid mobilization is the conditio sine qua non for behavioral invigoration evoked by external cues. Reward- and punishment-predictive signals require intact retrograde release of the endocannabinoid 2-arachidonoylglycerol (2-AG) from ventral tegmental area dopamine neurons. Moreover, we show that genetic deletion of presynaptic cannabinoid type-1 receptors (CB1Rs), the target for 2-AG, recapitulates behavioral and dopaminergic deficits. Exploiting causal inference tools to interpret continuous brain signals, we describe that 2-AG/CB1R communication is essential for striatal dopamine release to signal salient cues and propel conditioned responding. These findings reveal an endocannabinoid-mediated disinhibition mechanism exploited by dopamine neurons to orchestrate striatal dopamine release events, enabling adaptive action selection informed by cues.

Stimulus-specific adaptation is a key feature of sensory systems, where the repeated presentation of a stimulus results in diminishing neuronal responses specifically to that stimulus, but not to a different stimulus. Cortical neurons display varying degrees of stimulus-specific adaptation, with cortical circuits shaping the dynamics of these responses. Here, we use calcium imaging and optogenetic approaches to assess the contributions of SOM and PV neurons to stimulus-specific adaptation in the mouse auditory cortex. We find opposing and complementary effects of SOM and PV neurons on the adaptation of principal neurons which manifest as context-dependent SOM neuron-mediated enhancement and PV-neuron mediated suppression of responses that depend on the temporal repetition rate of the sounds. Our results suggest that SOM and PV neurons can engage in multiple operating regimes that exist in a continuum during sensory processing.

Our ability to generalize abstract rules to new situations is a cognitive hallmark, yet its neural basis is unclear. We identified a thalamocortical circuit essential for this process in mice. During a cross-modal rule transfer task, medial prefrontal cortex (mPFC) neurons encoded task rules across sensory modalities to enable generalization. Crucially, mediodorsal thalamus (MD) projections to mPFC were causally required: Inhibiting this pathway destabilized mPFC representations and impaired rule transfer, whereas enhancing it improved performance. Without MD input, mPFC recruited distinct populations for each task, losing cross-context stability. Direct mPFC excitation impaired generalization, underscoring the specificity of thalamic regulation. Thus, the MD stabilizes mPFC activity for flexible rule transfer—a mechanism with implications for cognitive disorders and artificial intelligence.

Traumatic brain injuries (TBIs) are more than mere lesions and generate a persistent secondary pathology. This, combined with functional reorganization of circuits post-injury, may explain the increased risk for psychiatric disorders in patients with TBI. In the current studies, we demonstrate that frontal TBI changed the Pavlovian behavioral response to reinforcer-predicting cues and reduced the motivational value of cues. TBI also chronically impaired decision-making on a gambling-like task with reinforcer-paired cues. To investigate how these changes occur, we evaluated the nucleus accumbens (NAc) core. At a subacute time point (14 days), we confirmed reduced input to the NAc with optogenetics and evaluated electrophysiological and transcriptional changes. TBI increased neuronal excitability and the single nucleus RNA sequencing profile indicated a substantial stress and inflammatory response, but also high indicators of plasticity, particularly in D1- and D2-positive medium spiny neurons. To evaluate how these subacute changes transitioned to chronic NAc dysfunction, we measured immunohistochemical surrogates of activity post-mortem and recorded calcium activity from the NAc after TBI during Pavlovian conditioning. TBI reduced histological markers of activity and reduced cue-evoked calcium activity. Overall, these data indicate that substantial reorganization of the NAc occurs following frontal brain injury. A primary effect of this is to reduce the salience of environmental cues linked to outcomes. The inability to properly process outcomes could contribute to broader psychiatric symptoms after TBI, including impairments in decision-making, behavioral flexibility, and impulsivity but also presents a potential treatment target.

Across sensory modalities, peripheral deafferentation can induce maladaptive central plasticity that amplifies sensory responses while distorting affective processing, rendering innocuous stimuli unpleasant, intrusive, or even painful. Here, we examined the affective dimension of compensatory plasticity in a mouse model of hyperacusis by introducing noise-induced focal cochlear lesions and tracking maladaptive plasticity in the lateral amygdala (LA), a key limbic hub for sensory-affective valuation. Whereas control mice habituated to neutral sounds, mice with noise-induced hearing loss (NIHL) showed sustained LA hyperresponsivity and abnormally strong temporal coupling between calcium transients and pupil dilations, an autonomic index of arousal. NIHL also disrupted discriminative auditory threat learning, producing poorly selective, non-extinguishing enhancement of LA responses and freezing to both threatening and non-threatening sounds. We posited that potentiating inhibition in the higher-order auditory cortex (HO-AC), a prominent source of auditory sensory input to the LA, could reinstate normal affective sound processing after NIHL. Brief bouts of 40-Hz optogenetic activation of HO-AC parvalbumin-expressing inhibitory neurons (PVNs) durably reversed LA sensitization, normalized pupil-indexed arousal dynamics, and reinstated discriminative auditory threat memory. These findings identify cortical inhibitory potentiation as a strategy for reversing neural, autonomic, and behavioral signatures of distorted affective sound processing after peripheral sensory injury.

Tissue inflammation or nerve injury at the periphery can cause chronic pain. Although the spinal-cord-projecting neurons in the rostral ventromedial medulla (RVMSC neurons) can promote pain chronification1-4, the pathway by which peripheral injury signals drive these neurons is poorly understood1-3,5. Here we report a circuit loop that extends from the spinal cord to the ventral posterolateral thalamus and posterior complex of the thalamus, proceeds to the primary somatosensory cortex and returns to the spinal cord via the lateral superior colliculus, which in turn connects to μ-opioid-receptor-expressing RVMSC neurons. Silencing any node along this multisynaptic circuit has minimal effects on nociception in healthy mice, but can eliminate mechanical hypersensitization and restore normal nociceptive response thresholds in mouse models of inflammatory and neuropathic pain. In healthy mice, repetitive-but not acute-activation of each node in this circuit is sufficient to cause robust chronic mechanical hypersensitization. Our findings reveal a spino-brain-spinal cord circuit loop that links ascending and descending pathways and specifically drives chronic mechanical pain. This could enable the identification of cellular targets for treating chronic pain.

Objective. Low-intensity transcranial focused ultrasound (tFUS) offers high spatial specificity and deep brain penetration, representing a promising non-invasive approach for modulating brain activity and behavior. Although emerging studies indicate that tFUS can modulate pain-related behaviors in rodents and humans, the underlying network-level and cellular mechanisms remain unknown. This study investigates the effects of tFUS neuromodulation on inhibitory neural circuits in a humanized mouse model of chronic pain, integrating electrophysiological, molecular, and histological analyses across a cohort of 50 animals, including wild-type controls. Approach. A 128-element random array transducer was used to precisely target the pain-processing brain circuit, while a non-invasive and flexible 30-channel electroencephalography electrode was applied to record local evoked responses, topographical activity, and global excitation and inhibition dynamics, which were further validated by optogenetics experiments. Cellular-level modulation and safety outcomes were evaluated through blinded histological examination. Main results. We found that tFUS produced robust modulation of local and global brain activity, characterized by suppression of local theta oscillations and enhancement of network-level inhibitory dynamics. These electrophysiological patterns aligned with those observed during optogenetic activation of parvalbumin (PV) interneurons. Immunohistochemistry further showed significant increases in inhibitory neuronal markers, including elevated expressions of glutamate decarboxylase 67 and PV. Blinded histological assessment confirmed the absence of tissue damage, supporting the safety of the stimulation paradigm. Significance. These findings demonstrated that tFUS stimulation non-invasively engages PV GABAergic inhibitory circuits in a chronic pain mouse model, providing mechanistic insight and supporting its development as a precise and safe neuromodulation technology for clinical translation.

Every moment, a spotlight of attention roams our visual field to enhance detection of salient stimuli. While recent work suggests how the brain selects salient relevant stimuli (attentional focus), it is unknown if there are mechanisms that modulate attention to suit fluctuating target salience or internal needs (attentional strength). Here, using optical recordings and perturbations in mice performing a cued detection task, we report that rapid dynamics in both dorsal raphe (DR) activity and cortical serotonin (5HT) release selectively regulate attentional strength. In contrast to these rapid DR-5HT dynamics, we found previously reported reward-associated and slower dynamics were both unrelated to attention. Brief optogenetic DR-5HT suppression increased attentional strength and performance, whereas optogenetic excitation reduced attentional strength and performance. A computational model suggests DR-5HT’s inverse effects on attention arise from control of cortical suppression and divisive normalization. Collectively, our results demonstrate that the brain independently controls attentional strength and focus and defines rapid DR-5HT neuromodulation as a new regulator of attentional strength.

Social relationships, including dominance status, are powerful regulators of mental health, and social experiences impact the continued expression of these behaviors. However, very little is known about the neuronal mechanisms that regulate the positive reinforcing effects of aggression that underlie social dominance, including potential sex differences. To address this gap, we used viral-mediated gene expression in Syrian hamsters to investigate how nucleus accumbens neurons regulate behavioral adaptations caused by aggression and other social interactions in both males and females. We found that females, but not males, display an increase in the efficiency to establish aggression with repeated experience. Females also displayed a more rapid potentiation of calcium signals from nucleus accumbens neurons over repeated social interactions. Chemogenetic inhibition of nucleus accumbens neurons specifically decreased aggression in females. Optogenetic stimulation of excitatory synaptic input from the prefrontal cortex to the nucleus accumbens decreased social investigation in females but increased social investigation and reduced aggression in males. Collectively, these studies suggest that the activity of nucleus accumbens neurons drives behavioral adaptations related to social interactions in general, and aggressive experience in particular, in opposite directions in females and males. This mechanism may contribute to the enhanced reward for social interactions in females compared with males and help explain the sex differences in the susceptibility to disorders associated with deficits in social behavior.

How neuronal firing within a circuit encodes behavioural intensity, like running speed, is largely unknown. Projections from temporal association cortex (TeA) and superior colliculus (SC) to dorsal periaqueductal grey (dPAG) circuit can both trigger running behaviour. Using in vivo loose-patch recordings with circuit manipulations in mice, we quantified a firing - speed relationship and established its encoding model. Here, we report two behavioural patterns induced by circuit activation: backing away and rebound running. Mechanistically, dPAG CaMKIIα neurons receiving inputs from either TeA or SC, function as distinct “behavioural units”, controlling two “unit behaviours” of running and backing away, respectively. The unidirectional inhibition from the backing away unit to the running unit is mediated by somatostatin (SOM) neurons in dPAG, enabling transitions among four behavioural states: running, backing away, stopping, and rebound running. Both running and backing away behaviours follow a unified motor encoding model, quantified by a single-phase association equation.

A central goal in neuroscience is to clarify how neural circuits translate sensory input into adaptive behaviours. Although unisensory evoked escape circuits in mice are well defined, it remains unclear whether a single nucleus contains specialized sensory, sensory‒motor decision, and motor command neurons for escapes driven by distinct sensory cues, and how these neurons form functional microcircuits. Using multiple sensory stimuli in mice, we identified the temporal association cortex (TeA) as a critical escape hub. Combining in vivo electrophysiology, optogenetics and chemogenetics, we characterized three distinct neuron subtypes within TeA layer 5 (L5) CaMKII neurons that correspond to these three functional classes. Intratelencephalic (IT) neurons serve as sensory‒motor decision neurons, while layer matched pyramidal tract (PT) neurons projecting to the dorsal periaqueductal grey (dPAG) act as motor command neurons. We reveal a laminar IT–PT microcircuit that converts sensory input into sensory-motor decisions and commands for escape locomotion.

In uncertain, threatening environments, rapid and flexible behavioral decisions are essential for survival. The ventral CA1 region of the hippocampus encodes threatening contexts and can regulate avoidance-related behaviors. While activity patterns in excitatory neurons of vCA1 have been well characterized, the contributions of specific interneuron subtypes to avoidance decisions in threatening situations remain to be fully elucidated. Here, we show that somatostatin expressing (SST) interneurons in vCA1 are selectively recruited during avoidance behavior and play a causal role in shaping behavioral responses in aversive spaces. We find that vCA1 SST interneurons ramp their activity in anticipation of, and during, avoidance. This contrasted with parvalbumin (PV) and vasoactive intestinal peptide (VIP) interneurons, which are preferentially active during exploratory approach behaviors. Unlike other classes of vCA1 interneurons, SST neuron activity more reliably represented the animal’s intention to avoid rather than its spatial position. Moreover, optogenetic silencing of SST interneurons reduced the efficiency of approach-avoidance decisions. These findings identify vCA1 SST interneurons as key regulators of threat assessment, revealing a cell-type-specific mechanism by which vCA1 microcircuits govern avoidance behaviors. This work provides a new framework for understanding hippocampal control of avoidance behavior and highlights SST-expressing interneurons as key contributors to anxiety-related behaviors.