Publications using the Lux

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.

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 ventral pallidum (VP) is a key basal ganglia structure involved in integrating reward-related signals to guide motivated behavior and feeding. VP neuronal activity is strongly tuned to reward-predictive cues and palatable rewards, tracking changes in value and motivational state. Recent studies have established important and opposing roles for GABAergic and glutamatergic VP neurons in reward- and avoidance-related behaviors. However, much less is known about the role of VP cholinergic neurons (VP-CNs), which comprise only ∼10% of VP neurons in mice, but maintain extensive connectivity with reward-related circuitry. Here, using cell type-selective in vivo fiber photometry during instrumental reward behavior, we found that VP-CN activity responds to cues, actions, and reward retrieval in a training-independent manner. Phasic VP-CN responses to reward retrieval were reduced by reward dilution, whereas pre-feeding with the reward enhanced these responses. In contrast, non-cholinergic VP neurons exhibited modulation by pre-feeding but not by reward dilution. Together, these findings identify VP-CNs as a distinct and dynamically regulated VP population whose activity is sensitive to both reward palatability and physiological state, extending our current understanding of the VP and its roles in reward processing.

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.

The ability to associate environmental stimuli with positive outcomes is a fundamental form of learning. While extensive research has focused on midbrain dopamine neurons during associative learning, less is known about learning-mediated changes in the afferents that shape dopamine neuron responses. We demonstrate in rats that during critical phases of learning, anion homeostasis in midbrain inhibitory GABA neurons - a primary source of input to dopamine neurons - is disrupted due to downregulation of the potassium chloride cotransporter KCC2. This alteration in GABA neurons preferentially impacted lateral mesoaccumbal dopamine pathways and was not observed after learning was established. At the network level, learning-mediated KCC2 downregulation was associated with enhanced synchronization between individual GABA neurons and increased dopamine responses to rewards and reward-related stimuli. Conversely, enhancing KCC2 function during learning reduced GABA synchronization, diminished relevant dopamine signaling, and prevented cue-reward associations. Thus, circuit-specific adaptations in midbrain GABA neurons are crucial for forming new reward-related behaviors.

Background CLN3 disease, also known as juvenile Batten disease, is a recessively inherited neurodevelopmental disorder caused by mutations in the CLN3 gene. It represents the most common form of Neuronal Ceroid Lipofuscinoses (NCLs), a group of lysosomal storage disorders that impair brain function. Clinical features include progressive vision loss, language impairment, and cognitive decline. The early onset of visual deficits complicates the neurological assessment of cognitive dysfunction, while the rarity of CLN3 cases limits the study of sex-specific disease trajectories in humans. Therefore, there is a critical need for objective, translational biomarkers to monitor disease progression and support therapeutic development in preclinical animal models. Methods Building on our recent studies in individuals with CLN3 disease, we developed a parallel experimental paradigm using high-density electroencephalography (EEG) in Cln3 knockout ( Cln3-/-) mice to longitudinally assess auditory neurophysiological changes. We applied a duration-based mismatch negativity (MMN) paradigm, similar to that used in our human studies, to evaluate automatic detection of auditory pattern changes in male and female mice between 3 and 9 months of age. Results Wild-type (WT) mice of both sexes showed robust and stable duration MMN responses across this age range. In contrast, Cln3-/- mice showed marked sex- and age-dependent deficits: female mutants displayed persistent MMN deficits, whereas male mutants exhibited early MMN abnormalities that unexpectedly improved with age. Auditory brainstem responses confirmed intact peripheral hearing in Cln3-/- mice, indicating a central origin for the observed abnormalities. Further analyses revealed that MMN impairments were driven by age- and sex-specific alterations in auditory evoked potentials to both standard and deviant stimuli. Conclusions These findings demonstrate sex- and age-dependent disruptions in central auditory processing in Cln3-/- mice and support auditory duration MMN as a sensitive, translational biomarker of brain dysfunction in CLN3 disease. This approach offers a functional, cross-species measure for tracking disease progression and evaluating therapeutic interventions in Batten disease.

Classical neuromodulators regulate arousal states, spanning deep sleep to vigilant wakefulness, primarily by activating cortical neurons. However, cortical astrocytes also express neuromodulatory G-protein-coupled receptors (GPCRs). While astrocytic noradrenergic receptors have been shown to modulate two critical regulators of arousal—cortical synchrony and extracellular adenosine levels—how other neuromodulatory signaling pathways similarly shape arousal remains unclear. Astrocytes in mammalian cortex express particularly high levels of the wake-promoting, Gq-coupled histamine-1-receptor (H1R), yet little is known about how astrocytic H1R contributes to regulation of arousal. To address this gap, we used pharmacological and genetic approaches in murine cortex to test how astrocyte-H1R signaling affects astrocyte calcium (Ca 2+ ), cortical neural activity across sleep/wake, and extracellular adenosine—an astrocytic output that regulates cortical arousal. Using ex vivo two-photon Ca 2+ imaging in acute cortical slices, we show that H1R mediates cell-autonomous astrocyte Ca 2+ responses to histamine (HA) and attenuates responses to norepinephrine (NE). Next, in vivo fiber photometry and electrophysiology results show that H1R deletion in cortical astrocytes disrupts local astrocyte Ca 2+ during wake and extracellular adenosine dynamics specifically around REM sleep transitions, when HA release is minimal. Further, astrocyte-specific H1R deletion in cortex promotes wakefulness and reduces REM sleep time. Our results indicate that H1R activity modulates astrocyte responses to non-histaminergic inputs by inducing lasting changes in astrocyte physiology that modulate extracellular adenosine and REM sleep. Our findings contribute to an emerging model in which neuromodulator GPCRs synergistically shape astrocyte physiology to regulate arousal behavior and adenosine signaling in the cortex.

Post-traumatic stress disorder (PTSD) develops in a sub-population of people exposed to trauma and is highly comorbid with opioid use disorder (OUD). The neurobiology of comorbid PTSD+OUD, especially with respect to sex differences, is poorly understood. Here we investigated the sex-specific effects of predator scent stress on intravenous (IV) oxycodone self-administration (SA), cue-primed reinstatement, and pre- and post-stress corticosterone (CORT) concentrations. Upon detecting effects of stress on oxycodone IVSA, the nucleus accumbens (NA) dopamine response to oxycodone was assessed. Male and female rats received a single 10-minute exposure to the predator scent TMT or the control condition. One week later, rats were tested for anxiety-like behavior on the elevated plus maze and underwent oxycodone IVSA, instrumental extinction, and a cue-primed reinstatement test. In a separate cohort of only female rats, the NA core dopamine response to IV oxycodone (0, 0.25, 0.5 mg/kg) was assessed using fiber photometry. TMT increased anxiety-like behavior one week later in male and female rats. Baseline CORT was negatively correlated with anxiety-like behavior in males. TMT exposure reduced oxycodone intake exclusively in females, with no effects on instrumental extinction or cue-primed reinstatement in either sex. Female rats demonstrated a dose-dependent increase in NA core dopamine signal following oxycodone administration that was blunted by a history of TMT exposure. These results indicate that TMT exposure diminishes the NA core dopamine response to oxycodone in females, reducing oxycodone IVSA. These results are consistent with stress-induced reward insensitivity that has been observed following stress in both rodents and humans.

Animals continuously adapt their behavior to balance survival and fulfilling essential needs. This balancing act involves prioritization of safety over the pursuit of other needs. However, the specific deep brain circuits that regulate safety-seeking behaviors in conjunction with motor circuits remain poorly understood. Here, we identify a class of glutamatergic neurons in the mouse lateral hypothalamic area (LHA) that target the midbrain locomotor-promoting pedunculopontine nucleus (PPN). Following activation, this LHA-PPN pathway orchestrates context-dependent locomotion, prioritizing safety-directed movement over other essential needs such as foraging or social contact. Remarkably, the neuronal activity of this circuit correlates directly with safety-seeking behavior. The circuit may respond to both intrinsic and extrinsic cues, having a pivotal role in ensuring survival. Our findings uncover a circuit motif within the lateral hypothalamus that, when recruited, prioritizes critical needs through the recruitment of an appropriate motor action.

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.

Objective: Dietary protein restriction induces adaptive changes in food preference, increasing protein consumption over carbohydrates or fat. We investigated whether motivation and reward signaling underpin these preferences. Methods and results: In an operant task, protein-restricted male mice responded more for liquid protein rewards, but not carbohydrate, fat, or sweet rewards compared to non-restricted mice. When the number of responses required to access protein reward varied, protein-restricted mice exhibited higher operant responses at moderate to high response requirements. The protein restriction-induced increase in operant responding for protein was absent in Fgf21-KO mice and mice with neuron-specific deletion of the FGF21 co-receptor beta-Klotho (KlbCam2ka). Fiber photometry recording of VTA dopamine neurons revealed that oral delivery of maltodextrin triggered a larger dopamine neuron activation than casein in control diet-fed mice, while casein triggered a larger activation in low-protein diet-fed mice. This restriction-induced shift in nutrient-specific VTA dopamine signaling was lost in Fgf21-KO mice. Conclusion: These data suggest that the increased FGF21 during protein restriction acts in the brain to induce a protein-specific appetite by specifically enhancing the reward value of protein-containing foods and the motivation to consume them.

Episodic memories are temporally segmented around event boundaries that tend to coincide with moments of environmental change. During these times, the state of the brain should change rapidly, or reset, to ensure that the information encountered before and after an event boundary is encoded in different neuronal populations. Norepinephrine (NE) is thought to facilitate this network reorganization. However, it is unknown whether event boundaries drive NE release in the hippocampus and, if so, how NE release relates to changes in hippocampal firing patterns. The advent of the new GRAB NE sensor now allows for the measurement of NE binding with sub-second resolution. Using this tool in mice, we tested whether NE is released into the dorsal hippocampus during event boundaries defined by unexpected transitions between spatial contexts and presentations of novel objections. We found that NE binding dynamics were well explained by the time elapsed after each of these environmental changes, and were not related to conditioned behaviors, exploratory bouts of movement, or reward. Familiarity with a spatial context accelerated the rate in which phasic NE binding decayed to baseline. Knowing when NE is elevated, we tested how hippocampal coding of space differs during these moments. Immediately after context transitions we observed relatively unique patterns of neural spiking which settled into a modal state at a similar rate in which NE returned to baseline. These results are consistent with a model wherein NE release drives hippocampal representations away from a steady-state attractor. We hypothesize that the distinctive neural codes observed after each event boundary may facilitate long-term memory and contribute to the neural basis for the primacy effect.

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.

Failure to appropriately predict and titrate reactivity to threat is a core feature of fear and anxiety-related disorders and is common following early life adversity (ELA). A population of neurons in the lateral central amygdala (CeAL) expressing corticotropin releasing factor (CRF) have been proposed to be key in processing threat of different intensities to mediate active fear expression. Here, we use in vivo fiber photometry to show that ELA results in sex-specific changes in the activity of CeAL CRF+ neurons, yielding divergent mechanisms underlying the augmented startle in ELA mice, a translationally relevant behavior indicative of heightened threat reactivity and hypervigilance. Further, chemogenic inhibition of CeAL CRF+ neurons selectively diminishes startle and produces a long-lasting suppression of threat reactivity. These findings identify a mechanism for sex-differences in susceptibility for anxiety following ELA and have broad implications for understanding the neural circuitry that encodes and gates the behavioral expression of fear.

Serotonergic neurons in the rostral ventral medulla (RVM) contribute to bidirectional control of pain through modulation of spinal and trigeminal nociceptive networks. Deficits in this pathway are believed to contribute to pathologic pain states, but whether changes in serotonergic mechanisms are pro- or antinociceptive is debated. We used a combination of optogenetics and fiber photometry to examine these mechanisms more closely. We find that optogenetic activation of RVM serotonergic afferents in the spinal cord of naive mice produces mechanical hypersensitivity and conditioned place aversion (CPA). Neuropathic pain, produced by chronic constriction injury of the infraorbital nerve (CCI-ION), evoked a tonic increase in serotonin (5HT) concentrations within the spinal trigeminal nucleus caudalis (SpVc), measured with liquid chromatography-tandem mass spectroscopy (LC-MS/MS). By contract, CCI-ION had no effect on the phasic serotonin transients in SpVc, evoked by noxious pinch, and measured with fiber photometry of a serotonin sensor. These findings suggest that serotonin release in the spinal cord is pronociceptive and that an increase in sustained serotonin signaling, rather than phasic or event driven increases, potentiate nociception in models of chronic pain.

The parabrachial complex (PB) is critically involved in aversive processes, and chronic pain is associated with amplified activity of PB neurons in rodent models of neuropathic pain. Here, we demonstrate that catecholaminergic input from the caudal nucleus of the solitary tract (cNTS cat ), a stress responsive region that integrates interoceptive and exteroceptive signals, causes amplification of PB activity and their sensory afferents. We used a virally mediated expression of a norepinephrine (NE) sensor, NE2h, fiber photometry, and extracellular recordings in anesthetized mice to show that noxious mechanical and thermal stimuli activate cNTS neurons. These stimuli also produce prolonged NE transients in PB that far outlast the noxious stimuli. Similar NE transients can be evoked by focal electrical stimulation of cNTS, a region that contains the noradrenergic A2 cell group that projects densely on PB. In vitro , optical stimulation of cNTS cat terminals depolarized PB neurons and caused a prolonged increase the frequency of excitatory synaptic activity. A dual opsin approach showed that sensory afferents from the caudal spinal trigeminal nucleus are potentiated by cNTS cat terminal activation. This potentiation was coupled with a decrease in the paired pulse ratio (PPR), consistent with an cNTS cat -mediated increase in the probability of release at SpVc synapses. Together, these data suggest that A2 neurons of the cNTS generate long lasting NE transients in PB which increase excitability and potentiate responses of PB neurons to sensory inputs. These reveal a mechanism through which stressors from multiple modalities may potentiate the aversiveness of nociceptive stimuli.

Sleep is not homogenous but contains a highly diverse microstructural composition influenced by neuromodulators. Prior methods used to measure neuromodulator levels in vivo have been limited by low time resolution or technical difficulties in achieving recordings in a freely moving setting, which is essential for natural sleep. In this protocol, we demonstrate the combination of electroencephalographic (EEG)/electromyographic (EMG) recordings with fiber photometric measurements of fluorescent biosensors for neuromodulators in freely moving mice. This allows for real-time assessment of extracellular neuromodulator levels during distinct phases of sleep with a high temporal resolution.

The prefrontal cortex (PFC) is a hub for cognitive control, and dopamine profoundly influences its functions. In other brain regions, astrocytes sense diverse neurotransmitters and neuromodulators and, in turn, orchestrate regulation of neuroactive substances. However, basic physiology of PFC astrocytes, including which neuromodulatory signals they respond to and how they contribute to PFC function, is unclear. Here, we characterize divergent signaling signatures in mouse astrocytes of the PFC and primary sensory cortex, which show differential responsiveness to locomotion. We find that PFC astrocytes express receptors for dopamine but are unresponsive through the Gs/Gi-cAMP pathway. Instead, fast calcium signals in PFC astrocytes are time locked to dopamine release and are mediated by α1-adrenergic receptors both ex vivo and in vivo. Further, we describe dopamine-triggered regulation of extracellular ATP at PFC astrocyte territories. Thus, we identify astrocytes as active players in dopaminergic signaling in the PFC, contributing to PFC function though neuromodulator receptor crosstalk.