Learning-associated functional plasticity at hippocampal synapses remains largely unexplored. Here, in a single session of reward-based trace conditioning, we examine learning-induced synaptic plasticity in the dorsal CA1 hippocampus (dCA1). Local field-potential recording combined with selective optogenetic inhibition first revealed an increase of dCA1 synaptic responses to the conditioned stimulus (CS) induced during conditioning at both Schaffer collaterals to the stratum radiatum (Rad) and temporoammonic input to the lacunosum moleculare (LMol). At these dCA1 inputs, synaptic potentiation of CS-responding excitatory synapses was further demonstrated by locally blocking NMDA receptors during conditioning and whole-cell recording sensory-evoked synaptic responses in dCA1 neurons from naive animals. An overall similar time course of the induction of synaptic potentiation was found in the Rad and LMol by multiple-site recording; this emerged later and saturated earlier than conditioned behavioral responses. Our experiments demonstrate a cued memory-associated dCA1 synaptic plasticity induced at both Schaffer collaterals and temporoammonic pathways.
Animals ; CA1 Region, Hippocampal/physiology* ; Male ; Association Learning/physiology* ; Neuronal Plasticity/physiology* ; Cues ; Memory/physiology* ; Synapses/physiology* ; Conditioning, Classical/physiology* ; Excitatory Postsynaptic Potentials/physiology* ; Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors* ; Rats ; Optogenetics

The ventral anterior (VA) nucleus of the thalamus is a major target of the basal ganglia and is closely associated with the pathogenesis of Parkinson's disease (PD). Notably, the VA receives direct innervation from the hypothalamic histaminergic system. However, its role in PD remains unknown. Here, we assessed the contribution of histamine to VA neuronal activity and PD motor deficits. Functional magnetic resonance imaging showed reduced VA activity in PD patients. Optogenetic activation of VA neurons or histaminergic afferents significantly alleviated motor deficits in 6-OHDA-induced PD rats. Furthermore, histamine excited VA neurons via H1 and H2 receptors and their coupled hyperpolarization-activated cyclic nucleotide-gated channels, inward-rectifier K⁺ channels, or Ca²⁺-activated K⁺ channels. These results demonstrate that histaminergic afferents actively compensate for Parkinsonian motor deficits by biasing VA activity. These findings suggest that targeting VA histamine receptors and downstream ion channels may be a potential therapeutic strategy for PD motor dysfunction.
Animals ; Histamine/metabolism* ; Male ; Oxidopamine/toxicity* ; Rats ; Ventral Thalamic Nuclei/physiopathology* ; Rats, Sprague-Dawley ; Disease Models, Animal ; Parkinson Disease/metabolism* ; Neurons/physiology* ; Humans ; Optogenetics

Our research reveals the critical role of the suprachiasmatic nucleus (SCN) vasoactive intestinal peptide (VIP) neurons in mediating light-induced transient forgetting. Acute exposure to bright light selectively impairs trace fear memory by activating VIP neurons in the SCN, as demonstrated by increased c-Fos expression and Ca²⁺ recording. This effect can be replicated and reversed through optogenetic and chemogenetic manipulations of SCN VIP neurons. Furthermore, we identify the SCN → PVT (paraventricular nucleus of the thalamus) VIP neuronal circuitry as essential in this process. These findings establish a novel role for SCN VIP neurons in modulating memory accessibility in response to environmental light cues, extending their known function beyond circadian regulation and revealing a mechanism for transient forgetting.
Animals ; Vasoactive Intestinal Peptide/metabolism* ; Male ; Mice ; Neurons/metabolism* ; Suprachiasmatic Nucleus/physiology* ; Light ; Mice, Inbred C57BL ; Memory/physiology* ; Fear/physiology* ; Suprachiasmatic Nucleus Neurons/metabolism* ; Optogenetics ; Proto-Oncogene Proteins c-fos/metabolism*

The anterior cingulate cortex (ACC) has recently been proposed as a key player in the representation of itch stimuli. However, to date, little is known about the contribution of specific ACC interneuron populations to itch processing. Using c-Fos immunolabeling and in vivo Ca²⁺ imaging, we reported that both histamine and chloroquine stimuli-induced acute itch caused a marked enhancement of vasoactive intestinal peptide (VIP)-expressing interneuron activity in the ACC. Behavioral data indicated that optogenetic and chemogenetic activation of these neurons reduced scratching responses related to histaminergic and non-histaminergic acute itch. Similar neural activity and modulatory role of these neurons were seen in mice with chronic itch induced by contact dermatitis. Together, this study highlights the importance of ACC VIP⁺ neurons in modulating itch-related affect and behavior, which may help us to develop novel mechanism-based strategies to treat refractory chronic itch in the clinic.
Animals ; Pruritus/physiopathology* ; Vasoactive Intestinal Peptide/metabolism* ; Interneurons/metabolism* ; Gyrus Cinguli/metabolism* ; Mice ; Male ; Mice, Inbred C57BL ; Histamine ; Chloroquine ; Optogenetics ; Mice, Transgenic

OBJECTIVE: To determine whether the glutamatergic neurons in the paraventricular nucleus of the thalamus (PVT) is involved in the change of consciousness induced by propofol through a combination of behavioral and electroencephalography (EEG) recordings. METHODS: Healthy male VGluT2-IRES-Cre mice aged 8-12 weeks were used in this experiment. (1) The glutamatergic neurons in the PVT was selectively damaged, and its effect on propofol anesthesia induction and recovery times as well as the energy of EEG in different frequency bands were observed. (2) Optogenetics was utilized to selectively activate or inhibit glutamatergic neurons in the PVT to assess their influence on anesthesia induction and recovery times under propofol as well as the energy of EEG in different frequency bands. RESULTS: (1) Selective ablation of glutamatergic neurons in the PVT significantly delayed recovery from propofol anesthesia with statistical difference as compared with the control group (s: 409.43±117.49 vs. 273.71±51.52, P < 0.05), but had no significant effect on anesthesia induction time. During the recovery phase of propofol, selective ablation of glutamatergic neurons in the PVT exhibited higher α-wave (1-4 Hz) power and reduced β-wave (12-15 Hz) power as compared with the control group. (2) Optogenetic activation of glutamatergic neurons in the PVT significantly prolonged anesthesia induction time under propofol (s: 161.67±29.09 vs. 119.33±18.98, P < 0.05) while significantly shortening the recovery time from propofol anesthesia (s: 208.67±57.19 vs. 288.83±34.52, P < 0.05). During the induction phase of propofol, activation of glutamatergic neurons in PVT reduced α-wave and α-wave (8-12 Hz) power, while during the recovery phase, α-wave power significantly increased as compared with the control group. (3) Optogenetic inhibition of glutamatergic neurons in the PVT delayed recovery from propofol anesthesia (s: 403.50±129.06 vs. 252.83±45.31, P < 0.05), but had no significant effect on induction time. During both the induction phase and recovery phase of propofol, the optogenetic inhibition of glutamatergic neurons in the PVT exhibited increased α-wave power. CONCLUSION Glutamatergic neurons in the PVT are involved in the regulation of propofol anesthesia recovery process.
Animals ; Propofol/pharmacology* ; Mice ; Neurons/physiology* ; Male ; Electroencephalography ; Wakefulness ; Midline Thalamic Nuclei ; Optogenetics

Olfactory bulb is a critical component in encoding and processing olfactory signals, characterized by its intricate neural projections and networks dedicated to this function. It has been found that descending neural projections from the olfactory cortex and other advanced brain regions can modulate the excitability of olfactory bulb output neurons in the olfactory bulb, either directly or indirectly, which can further influence olfactory discrimination, learning, and other abilities. In recent years, advancements in optogenetic technology have facilitated extensive application of neuron manipulation for studying neural circuits, thereby greatly accelerating research into olfactory mechanisms. This review summarizes the latest research progress on the regulatory effects of neural projections from the olfactory cortex, basal forebrain, raphe nucleus, and locus coeruleus on olfactory bulb function. Furthermore, the important role that photogenetic technology plays in olfactory mechanism research is evaluated. Finally, the existing problems and future development trends in current research are preliminarily proposed and explained. This review aims to provide new insights into the mechanisms underlying olfactory neural regulation as well as applications of optogenetic technology, which are crucial for advancing the research on olfactory mechanism and the application of optogenetic technology.
Olfactory Bulb/physiology* ; Optogenetics/methods* ; Animals ; Humans ; Olfactory Pathways/physiology* ; Olfactory Cortex/physiology* ; Smell/physiology*

The looming stimulus-evoked flight response to approaching predators is a defensive behavior in most animals. However, how looming stimuli are detected in the retina and transmitted to the brain remains unclear. Here, we report that a group of GABAergic retinal ganglion cells (RGCs) projecting to the superior colliculus (SC) transmit looming signals from the retina to the brain, mediating the looming-evoked flight behavior by releasing GABA. GAD2-Cre and vGAT-Cre transgenic mice were used in combination with Cre-activated anterograde or retrograde tracer viruses to map the inputs to specific GABAergic RGC circuits. Optogenetic technology was used to assess the function of SC-projecting GABAergic RGCs (scpgRGCs) in the SC. FDIO-DTA (Flp-dependent Double-Floxed Inverted Open reading frame-Diphtheria toxin) combined with the FLP (Florfenicol, Lincomycin & Prednisolone) approach was used to ablate or silence scpgRGCs. In the mouse retina, GABAergic RGCs project to different brain areas, including the SC. ScpgRGCs are monosynaptically connected to parvalbumin-positive SC neurons known to be required for the looming-evoked flight response. Optogenetic activation of scpgRGCs triggers GABA-mediated inhibition in SC neurons. Ablation or silencing of scpgRGCs compromises looming-evoked flight responses without affecting image-forming functions. Our study reveals that scpgRGCs control the looming-evoked flight response by regulating SC neurons via GABA, providing novel insight into the regulation of innate defensive behaviors.
Animals ; Superior Colliculi/physiology* ; Retinal Ganglion Cells/physiology* ; GABAergic Neurons/physiology* ; Mice, Transgenic ; Mice ; Optogenetics ; Visual Pathways/physiology* ; Mice, Inbred C57BL ; Photic Stimulation/methods* ; gamma-Aminobutyric Acid/metabolism* ; Male

Chronic pain relief remains an unmet medical need. Current research points to a substantial contribution of glia-neuron interaction in its pathogenesis. Particularly, microglia play a crucial role in the development of chronic pain. To better understand the microglial contribution to chronic pain, specific regional and temporal manipulations of microglia are necessary. Recently, two new approaches have emerged that meet these demands. Chemogenetic tools allow the expression of designer receptors exclusively activated by designer drugs (DREADDs) specifically in microglia. Similarly, optogenetic tools allow for microglial manipulation via the activation of artificially expressed, light-sensitive proteins. Chemo- and optogenetic manipulations of microglia in vivo are powerful in interrogating microglial function in chronic pain. This review summarizes these emerging tools in studying the role of microglia in chronic pain and highlights their potential applications in microglia-related neurological disorders.
Humans ; Optogenetics ; Brain/physiology* ; Microglia ; Chronic Pain/therapy* ; Neurons/physiology*

Pain is an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage. The processing of pain involves complicated modulation at the levels of the periphery, spinal cord, and brain. The pathogenesis of chronic pain is still not fully understood, which makes the clinical treatment challenging. Optogenetics, which combines optical and genetic technologies, can precisely intervene in the activity of specific groups of neurons and elements of the related circuits. Taking advantage of optogenetics, researchers have achieved a body of new findings that shed light on the cellular and circuit mechanisms of pain transmission, pain modulation, and chronic pain both in the periphery and the central nervous system. In this review, we summarize recent findings in pain research using optogenetic approaches and discuss their significance in understanding the pathogenesis of chronic pain.
Brain ; Chronic Pain ; Humans ; Neurons ; Optogenetics ; Spinal Cord

In recent years, due to the emergence of ultrafast ultrasound imaging technology, the sensitivity of detecting slow and micro blood flow with ultrasound has been dramatically improved, and functional ultrasound imaging (fUSI) has been developed. fUSI is a novel technology for neurological imaging that utilizes neurovascular coupling to detect the functional activity of the central nervous system (CNS) with high spatiotemporal resolution and high sensitivity, which is dynamic, non-invasive or minimally invasive. fUSI fills the gap between functional magnetic resonance imaging (fMRI) and optical imaging with its high accessibility and portability. Moreover, it is compatible with electrophysiological recording and optogenetics. In this paper, we review the developments of fUSI and its applications in neuroimaging. To date, fUSI has been used in various animals ranging from mice to non-human primates, as well as in clinical surgeries and bedside functional brain imaging of neonates. In conclusion, fUSI has great potential in neuroscience research and is expected to become an important tool for neuroscientists, pathologists and pharmacologists.
Animals ; Mice ; Ultrasonography/methods* ; Brain/physiology* ; Magnetic Resonance Imaging ; Optogenetics ; Hemodynamics