Optogenetics publications

Optogenetic stimulation is widely used to establish causal links between neural activity, behavior, and sensory perception, yet animals may also perceive the neural stimulation itself, a phenomenon termed “optoception.” We hypothesized that cortical optogenetic stimulation would generate an artificial percept that could be distinguished from externally evoked sensations and characterized psychometrically in an operant task. We tested this hypothesis using mesoscale cortical photostimulation delivered by a 3 mm, 459 nm LED implanted over auditory cortex. Four mice expressing Channelrhodopsin-2 (ChR2) in excitatory neurons learned a head-fixed go/no-go task in which 20 Hz cortical photostimulation served as the target. ChR2-positive mice detected cortical photostimulation relative to LED-off catch trials, distinguished it from both an external LED matched in wavelength and pulse rate and from an acoustic noise matched in amplitude-modulation rate, and discriminated between 20- and 10-Hz cortical photostimulation. Reducing implanted-LED optical power initially lowered rate-discrimination sensitivity, which then increased across training sessions, demonstrating perceptual learning. In two mice tested with 11 randomly interleaved rates spanning 10-20 Hz, lick probability followed a saturating rate-dependent function. Two ChR2-negative littermates failed to acquire photostimulation-locked behavioral responding. Together, these findings show that mesoscale cortical optogenetic stimulation generates a graded, learnable artificial percept whose behavioral readout depends on photostimulation rate and optical power. This single-LED preparation provides a cost-efficient and wavelength-extensible platform for psychometric analysis of optoception. SIGNIFICANCE STATEMENT Optogenetic stimulation can alter sensory processing, but the neural perturbation itself may also become a perceptual cue. We show that mice detect mesoscale cortical photostimulation delivered by a 3 mm implanted LED, distinguish it from matched external light and sound, and discriminate differences in photostimulation rate. When implanted-LED optical power was reduced, discrimination sensitivity initially declined and then increased across training sessions, revealing perceptual learning of optoception. Thus, mesoscale cortical photostimulation generates a graded internal signal whose behavioral readout depends on stimulation rate, optical power, and experience. A single implanted LED provides a cost- efficient and wavelength-extensible assay for measuring optogenetic perception.

Many species display mating-related sleep suppression to maximize reproductive success, yet the underlying neural mechanisms in mammals remain unclear. Here, we report that male mice exhibit delayed sleep onset and reduced sleep duration in periods following successful mating, while females are unaffected. Single-cell transcriptomics identifies a group of sleep-promoting Rxfp1-expressing neurons in the preoptic area of hypothalamus (POA Rxfp1 neurons), and fiber photometry reveals selective inhibition of them during and after mating in male mice. Lifting this inhibition via chemogenetic activation reverses sleep suppression in mated males. Monosynaptic retrograde tracing from these POA Rxfp1 neurons identifies male-biased γ-aminobutyric acid–releasing inputs from the principal nucleus of the bed nucleus of the stria terminalis (BNSTpr). Notably, optogenetic activation of these neurons induces immediate wakefulness specifically in male mice, and BNSTpr → POA Rxfp1 neurons are hyperactive after mating. Together, these findings establish a BNSTpr → POA Rxfp1 circuit that integrates reproductive signals for male-specific sleep suppression in mice.

The lateral habenula (LHb) integrates cortical and basal forebrain (BF) input and is implicated in negative affective states, but its involvement in negative affect associated with cannabis withdrawal is unknown. Here, effects of withdrawal from the psychoactive cannabis constituent, Δ 9 -tetrahydrocannabinol (Δ 9 -THC), on fear conditioning (FC) and LHb function were measured in rats using calcium photometry and electrophysiology. FC-associated LHb calcium signals, freezing behavior, and LHb excitatory-inhibitory (E-I) ratios were increased during Δ 9 -THC withdrawal, and local GABA release was impaired, indicating disinhibition of LHb output neurons. GABA release was also impaired at optogenetically activated BF-LHb axons, and not from ventral tegmental area-LHb inputs. The results indicate that Δ 9 -THC withdrawal increases LHb excitability through disinhibition, contributing to increased fear of primary and conditioned aversive stimuli. Our findings implicate the LHb in cannabis withdrawal-associated negative affect and offer insight into the neural mechanisms of cannabis use disorder.

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.

Recent work shows that the brain’s arousal system remains active during sleep, with rhythmic locus coeruleus (LC) activity shaping sleep architecture and supporting memory consolidation. The LC releases norepinephrine (NE) in infraslow (~0.02 Hz) bouts that gate NREM sleep spindles. Here, we demonstrate that heart rate (HR) fluctuations during NREM are tightly phase-locked to these NE rhythms, identifying the LC as a key driver of very-low-frequency HR variability (VLF-HRV), an understudied autonomic signal. Using optogenetics, transient LC inhibition blunts HR slowing, whereas LC activation produces rapid HR acceleration, demonstrating a direct LC-HR relationship during sleep that is maintained across a defined range of LC activity levels but breaks down when LC activity becomes excessive. We further show that infraslow HR variability is a cross-species marker of spindle-dependent memory processing. In mice, the amplitude of HR decelerations during NREM correlates with spindle activity and subsequent memory performance. Remarkably, human sleepers show the same pattern: stronger VLF-HR fluctuations during NREM correspond to increased spindle expression and better overnight memory retention. These findings reveal a mechanistic pathway through which graded changes in LC activity, up to a critical level, modulates autonomic physiology during sleep and identify infraslow HR variability as a non-invasive marker of brainstem function and memory-promoting sleep. Because LC degeneration occurs early in neurodegenerative disease, sleep-derived HR metrics may provide a scalable indicator of emerging neuromodulatory dysfunction.

Brain function relies on coordinated activity across spatial and temporal scales. Single neurons integrate local and long-range connectivity and reflect activity across brain-wide networks. Understanding integrated brain function requires tools capable of recording from anatomically connected populations in distributed brain areas to bridge local and global dynamics. Here, we present high-density, micro-electrocorticography arrays that facilitate multi-scale studies of brain activity. The hybrid arrays integrate the desirable features of silicone elastomers and polyimide films: silicone provides optical transparency and permits repeated penetration with intracortical arrays, while polyimide enables fine photolithographic feature definition. This combination facilitates high-throughput functional mapping to identify targets and insertion of intracortical arrays for dense local sampling. We demonstrate functional mapping in rats, cats, and marmosets, showing how functional maps guide multi-area laminar recordings. Finally, we demonstrate local and feedforward optogenetic stimulation to investigate cortico-cortical interactions. These capabilities establish the hybrid μECoG as a compelling tool for systems neuroscience.

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.

Spontaneous calcium (Ca 2+ ) waves play a critical role as internal stimuli in the early developing auditory system before the onset of sensory experiences. However, neither the spatiotemporal control of spontaneous Ca 2+ waves nor their impacts on auditory development are well understood. Here we report that a lateral array of inner supporting cells (ISCs) beneath the inner hair cells displays a spontaneous ultra‐long, ultra‐fast, transient Ca 2+ flash, termed “Ca 2+ lightning”, which triggers a series of simultaneous bursts of Ca 2+ waves in the whole cochlea, before the ear canal opening. The Ca 2+ lightning margins the cochlear ISCs at different developmental stages that correspondingly exhibit different Ca 2+ activities. Triggered by an ATP‐induced high‐level Ca 2+ wave, the Ca 2+ lightning rapidly propagates laterally into neighboring ISCs through the intricate interplay of the T‐type Ca 2+ channel, Anoctamin 1 (Ano1) Ca 2+ ‐activated Cl − channel and Connexin 26 (Cx26). The genetic deletion of Cav3.2, Ano1, or Cx26 abrogates Ca 2+ lightning flashes and dysregulates cell development and functions in peripheral cochleae. We propose that cochlear Ca 2+ lightning flashes orderly with Ca 2+ waves together orchestrate the spatiotemporal maturation processes of the peripheral auditory system before the onset of hearing.

Perceived or volitional control over a stressor is a critical determinant of resilient versus susceptible behavioral phenotypes. Activation of the lateral habenula (LHb) is required for the behavioral changes or “learned helplessness” effects that follow inescapable, but not escapable, stress. However, the relevant LHb inputs that regulate its mediation of inescapable stress outcomes are not fully elucidated. We find that ventral tegmental area (VTA) glutamatergic axons in LHb are activated by aversive stimuli, and this activation was not altered by prior inescapable stress experience. Similarly, optogenetic activation of VTA glutamatergic axons in LHb resulted in c-Fos expression in LHb neurons that did not depend on a prior inescapable stress experience. Photoinhibition of VTA glutamatergic axons in LHb during each inescapable stress trial prevented social and nonsocial consequences of inescapable stress. We interpret these results such that VTA glutamatergic inputs to LHb report aversive stimuli to LHb, possibly related to current salient aversive experience without regard to prior stress history. Nevertheless, VTA glutamatergic input to the LHb plays an important role in regulating LHb-mediated social and nonsocial consequences of uncontrollable stress.

The parabrachial nucleus (PBN) is an important hub located in the pons that relays sensory signals from peripheral regions. It is genetically diverse and contains many populations that modulate feeding and responses to threatening situations. A small Ntsr1 -expressing population of neurons was identified that projects selectively to the ventromedial hypothalamus (VMH). The Ntsr1 neurons are scattered throughout the lateral PBN with a cluster of cells along the border to the nucleus of the lateral lemniscus that overlap with Cck and Foxp2 expression. Chemogenetic activation of PBN Ntsr1 neurons results in Fos induction in Nr5a1 (SF1) and Bdnf neurons in the VMH. Activation of PBN Ntsr1 neurons or their terminals in the VMH reduces food intake after fasting and increases anxiety-like behaviors. In anxiogenic feeding assays, activation of PBN Ntsr1 neurons increases latency to feed as well as reducing food intake. Photometry showed that PBN Ntsr1 -neuronal activity increases during anxiogenic situations but is suppressed during food consumption, suggesting a role in threat-induced suppression of feeding. Silencing PBN Ntsr1 neurons with tetanus toxin light-chain increased food intake and reduced anxiety. These findings reveal a genetically defined PBN to VMH circuit that responds to threats and suppresses feeding behavior.

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.

Brain neuromodulatory systems exert powerful effects on local neuronal circuit function and behavior. In addition to classical actions directly on neurons, growing evidence indicates that neuromodulators also recruit Ca 2+ -dependent astrocyte mechanisms to regulate synaptic plasticity and network function. The dorsal striatum integrates cortical and thalamic inputs under strong dopamine (DA) and acetylcholine (ACh) neuromodulatory control. To what extent the circuit and behavioral effects of striatal ACh and DA depend on astrocyte Ca 2+ activity remains unclear. We show that locomotion elicits robust DA, ACh, and astrocyte Ca 2+ activity in the dorsolateral striatum (DLS). DA and ACh release exhibits a negative correlation on a fast time scale but shows a positive correlation during continuous locomotion as slower astrocyte Ca 2+ activity builds. Higher ACh and DA release is associated with higher astrocyte events, suggesting that both neurotransmitters drive astrocyte activity. In agreement, pharmacological blockade of muscarinic ACh or D1/D2 DA receptors decreases locomotion-evoked astrocyte Ca 2+ . Closed-loop optogenetic inhibition of striatal cholinergic interneurons (CINs) during locomotion reduces astrocyte Ca 2+ activity, demonstrating a causal contribution of ACh release to astrocyte activity. Locomotion related ACh release was severely compromised in a mouse model of Parkinson’s disease (PD), with the dual loss of DA and ACh attenuating astrocyte Ca 2+ activity. Facilitating astrocyte cholinergic signaling via chemogenetics improved both calcium activity and motor deficits in our recent work. Thus, the pathophysiology of PD in part involves attenuated astrocyte Ca 2+ signaling, placing these non-neuronal cells as a prime underexplored therapeutic target for PD.

Introduction: Transcranial focused ultrasound (tFUS) can noninvasively modulate sensory pathways, but the cell-type-specific mechanisms underlying excitatory or inhibitory effects remain unclear. Here, we investigate how tFUS applied to the somatosensory cortex (S1) influences S1 and posterior medial thalamic nucleus (POm) responses to hind paw vibration-tactile stimulation and which neuronal populations mediate these effects. Methods: Vibration-tactile stimulation evoked potentials (TEPs) and multi-unit activity (MUA) in S1 and POm were recorded from male rats. Optogenetic tagging was used to identify S1 CaMKII-positive, PV-positive, and SST-positive neurons, while waveform features were used to classify putative excitatory (i.e., regular-spiking units - RSUs) and inhibitory neurons (i.e., fast-spiking units - FSUs) in POm. Results: We found that only S1 CaMKII-positive neurons and POm RSUs responded robustly to tactile stimulation. When tFUS was applied to S1, high pulse repetition frequency (PRF), high duty cycle, and high-pressure stimulation (etFUS) produced excitatory modulation of the sensory pathway, whereas low PRF, low duty cycle, and low-pressure stimulation (itFUS) induced inhibitory effects. Further analyses suggested that excitatory modulation may involve activation of S1 CaMKII-positive neurons, while the inhibitory effect may be associated with their deactivation. Conclusions: These findings demonstrate that tFUS exerts bidirectional, parameter-dependent modulation of a sensory pathway and highlight the critical role of CaMKII-positive neurons in mediating these effects. This study provides mechanistic insight into cell-type-specific neuromodulation by tFUS, particularly in bidirectional modulation of a sensory pathway, and informs the optimization of stimulation parameters for targeted therapeutic interventions.

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.

In mammals, slow-wave sleep is characterized by synchronized neuronal activity that alternates between on and off periods. Slow-wave activity (SWA) and synchrony reflect sleep need, are correlated with synaptic strength in cortical circuits and promote synaptic downselection and memory consolidation. Here we assessed whether these core benefits of sleep can be obtained during waking. We locally induced alternating on/off periods during wakefulness using optogenetics in mice. This led to a local ipsilateral reduction in SWA and synchrony during subsequent sleep, and to reduced markers of synaptic strength. Moreover, bilateral induction of off periods over sensorimotor cortex during sleep deprivation restored memory consolidation. Thus, inducing on/off activity during wakefulness is sufficient to reduce local sleep need and fulfill core functions of sleep.

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.

Preparing and initiating movements at the right time is critical for goal-directed behavior. Before movement execution, motor cortical areas exhibit preparatory activity, which decreases from premotor to primary motor areas. During the shift from preparation to execution activity in neural state space transitions from movement-null to movement-potent dimensions. However, the circuit-level mechanisms underlying this shift remain unresolved. Here, we demonstrate that projections from the rat premotor cortex (rostral forelimb area [RFA]) to the primary motor cortex (caudal forelimb area [CFA]) encode primarily pre-movement activity. Optogenetic inhibition of these projections has behavioral effects comparable to inhibiting either RFA or CFA alone. During preparation, RFA projections enhance and suppress CFA neurons similarly, affecting activity along CFA's preparatory dimension. During movement, RFA's influence shifts predominantly to excitatory, aligning with CFA's movement-potent dimension. These results establish a mechanistic link between neural state space concepts and underlying circuit mechanisms, providing an intuitive model for movement control.

Cognitive dysfunction in conditions such as schizophrenia involves disrupted communication between the prefrontal cortex (PFC) and the mediodorsal thalamus (MD). Parvalbumin interneurons (PVIs) are known to regulate PFC microcircuits and generate synchronized gamma-frequency (∼40 Hz) neural oscillations that are recruited during many executive functions, necessary for cognitive flexibility, and deficient in schizophrenia. While targeting PVI-mediated gamma oscillations holds great therapeutic promise, their nature and specific functions, e.g., for regulating PFC→MD communication, remain elusive. Using dual-color voltage indicators and optogenetics in mice, we reveal that PVIs dynamically synchronize with MD-projecting PFC neurons both locally and contralaterally, creating multiple distinct circuit-specific patterns of distributed gamma synchronization that are recruited in a behaviorally specific manner to support particular aspects of flexible behavior. Thus, gamma oscillations are not unitary phenomena characterized by one microcircuit-wide pattern of synchrony. Rather, they comprise diverse motifs, defined by specific cell types and phase relationships, that are dynamically recruited for specific functions.