Optogenetics publications

The ability to evaluate valence of a social agent based on social experience is essential for an animal's survival in its social group1. Although hippocampal circuits have been implicated in distinguishing novel and familiar conspecifics2-7, it remains unclear how social valence is constructed on the basis of social history and what mechanisms underlie the heightened valence versatility in dynamic relationships. Here we demonstrate that the ventral (v)CA1 integrates serotonin (5-HT) inputs from the dorsal raphe and neurotensin inputs from the paraventricular nucleus of the thalamus (PVT) to determine positive or negative valence of conspecific representations. Specifically, during an appetitive social interaction 5-HT is released into the vCA1 and disinhibits pyramidal neurons through 5-HT1B receptors, whereas neurotensin is released during an aversive social interaction and potentiates vCA1 neurons directly through NTR1s. Optogenetic silencing of dorsal raphe 5-HT and PVT neurotensin inputs into the vCA1 impairs positive and negative social valence, respectively, and excitation flexibly switches valence assignment. These results show how aversive and rewarding social experiences are linked to conspecific identity through converging dorsal raphe 5-HT and PVT neurotensin signals in the vCA1 that instruct opposing valence, and represent a synaptic switch for flexible social valence computation.

Dopamine release in the nucleus accumbens (NAc) plays a critical role in the motivation to perform actions that promote survival. However, the NAc dopamine response to innately threatening visual stimuli, such as predators descending from above, and the innate behaviors they promote has not been fully characterized. Using the genetically encoded sensor dLight1, we investigated looming visual threat–evoked dopamine release in the lateral (LNAc) and medial NAc shell (NAcS) regions in freely moving mice during performance of a looming stimulus assay. We found that dopamine release related to visual threat perception in the NAcS, but not in the LNAc, predicts the timing and vigor of a future defensive action, yet dopamine released during the performance of the action itself does not. Optogenetic inhibition of dopaminergic terminals in the NAcS at visual stimulus onset prevented escape, confirming a role for ventral striatal dopamine in promoting threat-related behaviors.

Social novelty preference is an important aspect of social interaction for evaluating new threats and opportunities for survival, but the underlying neuronal mechanism remains unclear. Here, we identify a molecularly defined medial prefrontal cortex (mPFC) excitatory neuron subtype, located in layer 5 expressing Il1rapl2 , which is highly associated with social deficit disorders in genome-wide association studies and might be responsible for regulating social novelty preference. Using an Il1rapl2 -Cre mouse line, we show that chemogenetic activation of the mPFC Il1rapl2 -expressing neurons impairs social novelty preference but with little effect on sociability. In addition, fiber photometry recording indicates that this neuron subtype is inhibited when mice interact with novel but not with familiar mice. Furthermore, viral tracing and terminal manipulation reveal that basolateral amygdala (BLA)–projecting Il1rapl2 + neurons mediate the social novelty preference. Thus, our study uncovers a molecularly defined mPFC-BLA circuit that specifically regulates social novelty preference, highlighting that specific neuron subtypes and circuits could modulate distinct aspects of social behaviors.

Striatonigral neurons, traditionally known for promoting locomotion, comprise diverse subtypes with distinct transcriptomic profiles. However, their specific contributions to locomotor regulation remain incompletely understood. Using the genetic markers Kremen1 and Calb1 , we demonstrate in mouse models that Kremen1 + and Calb1 + striatonigral neurons exerted opposing effects on locomotion. Kremen1 + neurons displayed delayed activation at locomotion onset but exhibited increasing activity during locomotion offset. In contrast, Calb1 + neurons showed early activation at locomotion onset and decreasing activity during locomotion offset. Optogenetic activation of Kremen1 + neurons suppressed ongoing locomotion, whereas activation of Calb1 + neurons promoted locomotion. Activation of Kremen1 + neurons induced a greater reduction in dopamine release than Calb1 + neurons, followed by a post-stimulation rebound. Conversely, activation of Calb1 + neurons triggered an initial increase in dopamine release. Furthermore, genetic knockdown of GABA-B receptor Gabbr1 in Aldh1a1 + nigrostriatal dopaminergic neurons (DANs) reduced DAN inhibition and completely abolished the locomotion-suppressing effect of Kremen1 + neurons. Together, these findings reveal a cell type-specific mechanism within striatonigral neuron subtypes: Calb1 + neurons promote locomotion, while Kremen1 + neurons terminate ongoing movement by inhibiting Aldh1a1 + DAN activity via GABBR1 receptors.

Social behaviors are crucial for human connection and belonging, often impacted by conditions like Autism Spectrum Disorder (ASD). The mesoaccumbens pathway (ventral tegmental area (VTA) to the nucleus accumbense (NAc)) plays a pivotal role in social behavior and is implicated in ASD. However, the impact of ASD‐related mutations on social reward processing remains insufficiently explored. This study focuses on the Shank3 mutation, associated with a rare genetic condition and linked to ASD, examining its influence on the mesoaccumbens pathway during behavior, using the Shank3 ‐deficient rat model. Our findings indicate that Shank3 ‐deficient rats exhibit atypical social interactions, associated with altered neuronal activity of VTA dopaminergic and GABAergic neurons and reduced dopamine release in the NAc. Moreover, they demonstrate that manipulating VTA neuronal activity can normalize this behavior, providing insights into the effects of Shank3 mutations on social reward processing and identifying a potential neural pathway for intervention.

Sniffing is a motivated behavior displayed by nearly all terrestrial vertebrates. While sniffing is associated with acquiring and processing odors, sniffing is also intertwined with affective and motivated states. The systems which influence the display of sniffing are unclear. Here, we report that dopamine release into the ventral striatum in mice is coupled with bouts of sniffing and that stimulation of dopaminergic terminals in these regions drives increases in respiratory rate to initiate sniffing whereas inhibition of these terminals reduces respiratory rate. Both the firing of individual neurons and the activity of post-synaptic D1 and D2 dopamine receptor-expressing neurons are coupled with sniffing and local antagonism of D1 and D2 receptors squelches sniffing. Together, these results support a model whereby sniffing can be initiated by dopamine's actions upon ventral striatum neurons. The nature of sniffing being integral to both olfaction and motivated behaviors implicates this circuit in a wide array of functions.

Orchestrating complex behaviors, such as approaching and consuming food, is critical for survival. In addition to hypothalamus neuronal circuits, the nucleus accumbens (NAc) also controls appetite and satiety. However, specific neuronal subtypes of the NAc that are involved and how the humoral and neuronal signals coordinate to regulate feeding remain incompletely understood. Here we decipher the spatial diversity of neuron subtypes of the NAc shell (NAcSh) and define a dopamine receptor D1-expressing and Serpinb2- expressing subtype controlling food consumption in male mice. Chemogenetics and optogenetics-mediated regulation of Serpinb2 + neurons bidirectionally regulate food seeking and consumption specifically. Circuitry stimulation reveals that the NAcSh Serpinb2 →LH LepR projection controls refeeding and can overcome leptin-mediated feeding suppression. Furthermore, NAcSh Serpinb2 + neuron ablation reduces food intake and upregulates energy expenditure, resulting in reduced bodyweight gain. Our study reveals a neural circuit consisting of a molecularly distinct neuronal subtype that bidirectionally regulates energy homeostasis, providing a potential therapeutic target for eating disorders.

Genetically-encoded dopamine (DA) sensors enable high-resolution imaging of DA release, but their ability to detect a wide range of extracellular DA levels, especially tonic versus phasic DA release, is limited by their intrinsic affinity. Here we show that a human-selective dopamine receptor positive allosteric modulator (PAM) can be used to boost sensor affinity on-demand. The PAM enhances DA detection sensitivity across experimental preparations (in vitro, ex vivo and in vivo) via one-photon or two-photon imaging. In vivo photometry-based detection of optogenetically-evoked DA release revealed that DETQ administration produces a stable 31 minutes window of potentiation without effects on animal behavior. The use of the PAM revealed region-specific and metabolic state-dependent differences in tonic DA levels and enhanced single-trial detection of behavior-evoked phasic DA release in cortex and striatum. Our chemogenetic strategy can potently and flexibly tune DA imaging sensitivity and reveal multi-modal (tonic/phasic) DA signaling across preparations and imaging approaches.

The basal ganglia are essential for executing motor actions. How the basal ganglia engage spinal motor networks has remained elusive. Medullary Chx10 gigantocellular (Gi) neurons are required for turning gait programs, suggesting that turning gaits organized by the basal ganglia are executed via this descending pathway. Performing deep brainstem recordings of Chx10 Gi Ca 2+ activity in adult mice, we show that striatal projection neurons initiate turning gaits via a dominant crossed pathway to Chx10 Gi neurons on the contralateral side. Using intersectional viral tracing and cell-type-specific modulation, we uncover the principal basal ganglia–spinal cord pathway for locomotor asymmetries in mice: basal ganglia → pontine reticular nucleus, oral part (PnO) → Chx10 Gi → spinal cord. Modulating the restricted PnO → Chx10 Gi pathway restores turning competence upon striatal damage, suggesting that dysfunction of this pathway may contribute to debilitating turning deficits observed in Parkinson’s disease. Our results reveal the stratified circuit architecture underlying a critical motor program.

Objective: An environmental context, which reliably predicts food availability, can increase the appetitive food drive within the same environment context. However, hunger is required for the development of such a context-induced feeding (CIF) response, suggesting the neural circuits sensitive to hunger link an internal energy state with a particular environment context. Since Agouti related peptide (AgRP) neurons are activated by energy deficit, we hypothesised that AgRP neurons are both necessary and sufficient to drive CIF. Methods: To examine the role of AgRP neurons in the CIF process, we used fibre photometry with GCaMP7f, chemogenetic activation of AgRP neurons, as well as optogenetic control of AgRP neurons to facilitate acute temporal control not permitted with chemogenetics. Results: A CIF response at test was only observed when mice were fasted during context training and AgRP population activity at test showed an attenuated inhibitory response to food, suggesting increased food-seeking and/or decreased satiety signalling drives the increased feeding response at test. Intriguingly, chemogenetic activation of AgRP neurons during context training did not increase CIF, suggesting precise temporal firing properties may be required. Indeed, termination of AgRP neuronal photostimulation during context training (ON-OFF in context), in the presence or absence of food, increased CIF. Moreover, photoinhibition of AgRP neurons during context training in fasted mice was sufficient to drive a subsequent CIF in the absence of food. Conclusions: Our results suggest that AgRP neurons regulate the acquisition of CIF when the acute inhibition of AgRP activity is temporally matched to context exposure. These results establish acute AgRP inhibition as a salient neural event underscoring the effect of hunger on associative learning.

With concurrent global epidemics of chronic pain and opioid use disorders, there is a critical need to identify, target and manipulate specific cell populations expressing the mu-opioid receptor (MOR). However, available tools and transgenic models for gaining long-term genetic access to MOR+ neural cell types and circuits involved in modulating pain, analgesia and addiction across species are limited. To address this, we developed a catalog of MOR promoter ( MORp ) based constructs packaged into adeno-associated viral vectors that drive transgene expression in MOR+ cells. MORp constructs designed from promoter regions upstream of the mouse Oprm1 gene ( mMORp ) were validated for transduction efficiency and selectivity in endogenous MOR+ neurons in the brain, spinal cord, and periphery of mice, with additional studies revealing robust expression in rats, shrews, and human induced pluripotent stem cell (iPSC)-derived nociceptors. The use of mMORp for in vivo fiber photometry, behavioral chemogenetics, and intersectional genetic strategies is also demonstrated. Lastly, a human designed MORp ( hMORp ) efficiently transduced macaque cortical OPRM1 + cells. Together, our MORp toolkit provides researchers cell type specific genetic access to target and functionally manipulate mu-opioidergic neurons across a range of vertebrate species and translational models for pain, addiction, and neuropsychiatric disorders.

The endocannabinoid (eCB) system is a key modulator of glutamate release within limbic neurocircuitry and thus heavily modulates stress responsivity and adaptation. The ventral hippocampus (vHPC)-basolateral amygdala (BLA) circuit has been implicated in the expression of negative affective states following stress exposure and is modulated by retrograde eCB signaling. However, the mechanisms governing eCB release and the causal relationship between vHPC-BLA eCB signaling and stress-induced behavioral adaptations are not known. Here, we utilized in vivo optogenetic- and biosensor-based approaches to determine the temporal dynamics of activity-dependent and stress-induced eCB release at vHPC-BLA synapses. Furthermore, we demonstrate that genetic deletion of cannabinoid type-1 receptors selectively at vHPC-BLA synapses decreases active stress coping and exacerbates stress-induced avoidance and anhedonia phenotypes. These data establish the in vivo determinants of eCB release at limbic synapses and demonstrate that eCB signaling within vHPC-BLA circuitry serves to counteract adverse behavioral consequences of stress.

Interneuron populations within the nucleus accumbens (NAc) orchestrate excitatory-inhibitory balance, undergo experience-dependent plasticity, and gate-motivated behavior, all biobehavioral processes heavily modulated by endogenous cannabinoid (eCB) signaling. While eCBs are well known to regulate synaptic plasticity onto NAc medium spiny neurons and modulate NAc function at the behavioral level, how eCBs regulate NAc interneuron function is less well understood. Here, we show that eCB signaling differentially regulates glutamatergic and feedforward GABAergic transmission onto NAc somatostatin–expressing interneurons (NAc SOM+ ) in an input-specific manner, while simultaneously increasing postsynaptic excitability of NAc SOM+ neurons, ultimately biasing toward vHPC (ventral hippocampal), and away from BLA (basolateral amygdalalar), activation of NAc SOM+ neurons. We further demonstrate that NAc SOM+ are activated by stress in vivo and undergo stress-dependent plasticity, evident as a global increase in intrinsic excitability and an increase in excitation–inhibition balance specifically at vHPC, but not BLA, inputs onto NAc SOM+ neurons. Importantly, both forms of stress-induced plasticity are dependent on eCB signaling at cannabinoid type 1 receptors. These findings reveal eCB-dependent mechanisms that sculpt afferent input and excitability of NAc SOM+ neurons and demonstrate a key role for eCB signaling in stress-induced plasticity of NAc SOM+ -associated circuits.

Head-fixed behavioral experiments in rodents permit unparalleled experimental control, precise measurement of behavior, and concurrent modulation and measurement of neural activity. Here, we present OHRBETS (Open-Source Head-fixed Rodent Behavioral Experimental Training System; pronounced ‘Orbitz’), a low-cost, open-source platform of hardware and software to flexibly pursue the neural basis of a variety of motivated behaviors. Head-fixed mice tested with OHRBETS displayed operant conditioning for caloric reward that replicates core behavioral phenotypes observed during freely moving conditions. OHRBETS also permits optogenetic intracranial self-stimulation under positive or negative operant conditioning procedures and real-time place preference behavior, like that observed in freely moving assays. In a multi-spout brief-access consumption task, mice displayed licking as a function of concentration of sucrose, quinine, and sodium chloride, with licking modulated by homeostatic or circadian influences. Finally, to highlight the functionality of OHRBETS, we measured mesolimbic dopamine signals during the multi-spout brief-access task that display strong correlations with relative solution value and magnitude of consumption. All designs, programs, and instructions are provided freely online. This customizable platform enables replicable operant and consummatory behaviors and can be incorporated with methods to perturb and record neural dynamics in vivo.

Information transfer within neuronal circuits depends on the balance and recurrent activity of excitatory and inhibitory neurotransmission. Chloride (Cl − ) is the major central nervous system (CNS) anion mediating inhibitory neurotransmission. Astrocytes are key homoeostatic glial cells populating the CNS, although the role of these cells in regulating excitatory-inhibitory balance remains unexplored. Here we show that astrocytes act as a dynamic Cl − reservoir regulating Cl − homoeostasis in the CNS. We found that intracellular chloride concentration ([Cl − ] i ) in astrocytes is high and stable during sleep. In awake mice astrocytic [Cl − ] i is lower and exhibits large fluctuation in response to both sensory input and motor activity. Optogenetic manipulation of astrocytic [Cl − ] i directly modulates neuronal activity during locomotion or whisker stimulation. Astrocytes thus serve as a dynamic source of extracellular Cl − available for GABAergic transmission in awake mice, which represents a mechanism for modulation of the inhibitory tone during sustained neuronal activity.

The question of how the brain links behavioral and biological features of defensive responses has remained elusive. The importance of this problem is underscored by the observation that behavioral passivity in stress coping is associated with elevations in glucocorticoid hormones, and each may carry risks for susceptibility to a host of stress-related diseases. Past work implicates the medial prefrontal cortex (mPFC) in the top-down regulation of stress-related behaviors; however, it is unknown whether such changes have the capacity to buffer against the longer-lasting biological consequences associated with aversive experiences. Using the shock probe defensive burying test in rats to naturalistically measure behavioral and endocrine features of coping, we observed that the active behavioral component of stress coping is associated with increases in activity along a circuit involving the caudal mPFC and midbrain dorsolateral periaqueductal gray (PAG). Optogenetic manipulations of the caudal mPFC-to-dorsolateral PAG pathway bidirectionally modulated active (escape and defensive burying) behaviors, distinct from a rostral mPFC–ventrolateral PAG circuit that instead limited passive (immobility) behavior. Strikingly, under conditions that biased rats toward a passive coping response set, including exaggerated stress hormonal output and increased immobility, excitation of the caudal mPFC–dorsolateral PAG projection significantly attenuated each of these features. These results lend insight into how the brain coordinates response features to overcome passive coping and may be of importance for understanding how activated neural systems promote stress resilience.