Transcranial temporal interference stimulation (tTIS) is a novel non-invasive neuromodulation technique with the potential to precisely target deep brain structures. This study explores the neural and behavioral effects of tTIS on the superior colliculus (SC), a region involved in eye movement control, in mice. Computational modeling revealed that tTIS delivers more focused stimulation to the SC than traditional transcranial alternating current stimulation. In vivo experiments, including Ca²⁺ signal recordings and eye movement tracking, showed that tTIS effectively modulates SC neural activity and induces eye movements. A significant correlation was found between stimulation frequency and saccade frequency, suggesting direct tTIS-induced modulation of SC activity. These results demonstrate the precision of tTIS in targeting deep brain regions and regulating eye movements, highlighting its potential for neuroscientific research and therapeutic applications.
Animals ; Superior Colliculi/physiology* ; Transcranial Direct Current Stimulation/methods* ; Eye Movements/physiology* ; Male ; Mice ; Mice, Inbred C57BL

Sleep deprivation has been shown to exacerbate pain sensitivity and may contribute to the onset of chronic pain, yet the precise neural mechanisms underlying this association remain elusive. In our study, we explored the contribution of cholinergic neurons within the medial habenula (MHb) to hyperalgesia induced by sleep deprivation in rats. Our findings indicate that the activity of MHb cholinergic neurons diminishes during sleep deprivation and that chemogenetic stimulation of these neurons can mitigate the results. Interestingly, we did not find a direct response of MHb cholinergic neurons to pain stimulation. Further investigation identified the interpeduncular nucleus (IPN) and the paraventricular nucleus of the thalamus (PVT) as key players in the pro-nociceptive effect of sleep deprivation. Stimulating the pathways connecting the MHb to the IPN and PVT alleviated the hyperalgesia. These results underscore the important role of MHb cholinergic neurons in modulating pain sensitivity linked to sleep deprivation, highlighting potential neural targets for mitigating sleep deprivation-induced hyperalgesia.
Animals ; Habenula/physiology* ; Sleep Deprivation/physiopathology* ; Cholinergic Neurons/physiology* ; Male ; Hyperalgesia/physiopathology* ; Rats, Sprague-Dawley ; Rats ; Interpeduncular Nucleus/physiology* ; Pain Threshold/physiology* ; Midline Thalamic Nuclei/physiology* ; Neural Pathways/physiopathology*

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

OBJECTIVE: To establish an efficient protocol for directed differentiation of human induced pluripotent stem cells (hiPSCs) into functional midbrain dopaminergic progenitor cells (DAPs) in vitro. METHODS: hiPSCs were induced to differentiate into DAPs in two developmental stages. In the first stage (the first 13 days), hiPSCs were induced into intermediate cells morphologically similar to primitive neuroepithelial cells (NECs) in neural induction medium containing a combination of small molecule compounds. In the second stage, the intermediate cells were further induced in neural differentiation medium until day 28 to obtain DAPs. After CM-DiI staining, the induced DAPs were stereotactically transplanted into the right medial forebrain bundle (MFB) of rat models of Parkinson's disease (PD). Eight weeks after transplantation, the motor behaviors of PD rats was evaluated. Immunofluorescence assay of brain sections of the rats was performed at 2 weeks after transplantation to observe the survival, migration and differentiation of the transplanted cells in the host brain microenvironment. RESULTS: hiPSCs passaged stably on Matrigel showed a normal diploid karyotype, expressed the pluripotency markers OCT4, SOX2, and Nanog, and were positive for alkaline phosphatase. The primitive neuroepithelial cells obtained on day 13 formed dense cell colonies in the form of neural rosettes and expressed the neuroepithelial markers (SOX2, Nestin, and PAX6, 91.3%-92.8%). The DAPs on day 28 highly expressed the specific markers (TH, FOXA2, LMX1A and NURR1, 93.3-96.7%). In rat models of PD, the hiPSCs-DAPs survived and differentiated into TH⁺, FOXA2⁺ and Tuj1⁺ neurons at 2 weeks after transplantation. Eight weeks after transplantation, the motor function of PD rats was significantly improved as shown by water maze test (P < 0.0001) and apomorphine-induced rotation test (P < 0.0001) compared with rats receiving vehicle injection. CONCLUSION HiPSCs can be effectively induced to differentiate into DAPs capable of differentiating into functional neurons both in vivo and in vitro. In rat models of PD, the transplanted hiPSCs-DAPs can survive for more than 8 weeks in the MFB and differentiate into multiple functional neurocytes to ameliorate neurological deficits of the rats, suggesting the potential value of hiPSCs-DAPs transplantation for treatment of neurological diseases.
Humans ; Rats ; Animals ; Induced Pluripotent Stem Cells ; Cell Differentiation/physiology* ; Neurons ; Parkinson Disease ; Mesencephalon ; Cells, Cultured

The accumulation of pathological α-synuclein (α-syn) in the central nervous system and the progressive loss of dopaminergic neurons in the substantia nigra pars compacta are the neuropathological features of Parkinson's disease (PD). Recently, the findings of prion-like transmission of α-syn pathology have expanded our understanding of the region-specific distribution of α-syn in PD patients. Accumulating evidence suggests that α-syn aggregates are released from neurons and endocytosed by glial cells, which contributes to the clearance of α-syn. However, the activation of glial cells by α-syn species produces pro-inflammatory factors that decrease the uptake of α-syn aggregates by glial cells and promote the transmission of α-syn between neurons, which promotes the spread of α-syn pathology. In this article, we provide an overview of current knowledge on the role of glia and α-syn pathology in PD pathogenesis, highlighting the relationships between glial responses and the spread of α-syn pathology.
Humans ; Parkinson Disease/pathology* ; alpha-Synuclein/metabolism* ; Dopaminergic Neurons/metabolism* ; Pars Compacta/metabolism*

Pain is a multi-dimensional emotional experience, and pain sensation and pain emotion are the two main components. As for pain, previous studies only focused on a certain link of the pain transmission pathway or a certain key brain region, and there is a lack of evidence that connectivity of brain regions is involved in pain or pain regulation in the overall state. The establishment of new experimental tools and techniques has brought light to the study of neural pathways of pain sensation and pain emotion. In this paper, the structure and functional basis of the neural pathways involved in the formation of pain sensation and the regulation of pain emotion in the nervous system above the spinal cord level, including thalamus, amygdala, midbrain periaqueductal gray (PAG), parabrachial nucleus (PB) and medial prefrontal cortex (mPFC), are reviewed in recent years, providing clues for the in-depth study of pain.
Humans ; Pain ; Neural Pathways/physiology* ; Periaqueductal Gray/physiology* ; Brain ; Spinal Cord/physiology* ; Magnetic Resonance Imaging

Wernekink commissure syndrome is a rare midbrain syndrome with bilateral cerebellar dysfunction,eye movement disorder,and palatal myoclonus.Few cases of this syndrome have been reported in China,let alone those combined with hallucinations and involuntary groping.This paper reports the diagnosis and treatment of a case of Wernekink commissure syndrome with hallucinations and involuntary groping,aiming to enrich the knowledge about this disease for clinicians.
Humans ; Mesencephalon ; Ocular Motility Disorders/diagnosis* ; Spinal Cord ; Syndrome ; Hallucinations

Itch is an unpleasant sensation that provokes the desire to scratch. While acute itch serves as a protective system to warn the body of external irritating agents, chronic itch is a debilitating but poorly-treated clinical disease leading to repetitive scratching and skin lesions. However, the neural mechanisms underlying the pathophysiology of chronic itch remain mysterious. Here, we identified a cell type-dependent role of the anterior cingulate cortex (ACC) in controlling chronic itch-related excessive scratching behaviors in mice. Moreover, we delineated a neural circuit originating from excitatory neurons of the ACC to the ventral tegmental area (VTA) that was critically involved in chronic itch. Furthermore, we demonstrate that the ACC→VTA circuit also selectively modulated histaminergic acute itch. Finally, the ACC neurons were shown to predominantly innervate the non-dopaminergic neurons of the VTA. Taken together, our findings uncover a cortex-midbrain circuit for chronic itch-evoked scratching behaviors and shed novel insights on therapeutic intervention.
Mice ; Animals ; Gyrus Cinguli/physiology* ; Pruritus/pathology* ; Mesencephalon ; Cerebral Cortex/pathology* ; Neurons/pathology*

The superior colliculus (SC), one of the most well-characterized midbrain sensorimotor structures where visual, auditory, and somatosensory information are integrated to initiate motor commands, is highly conserved across vertebrate evolution. Moreover, cell-type-specific SC neurons integrate afferent signals within local networks to generate defined output related to innate and cognitive behaviors. This review focuses on the recent progress in understanding of phenotypic diversity amongst SC neurons and their intrinsic circuits and long-projection targets. We further describe relevant neural circuits and specific cell types in relation to behavioral outputs and cognitive functions. The systematic delineation of SC organization, cell types, and neural connections is further put into context across species as these depend upon laminar architecture. Moreover, we focus on SC neural circuitry involving saccadic eye movement, and cognitive and innate behaviors. Overall, the review provides insight into SC functioning and represents a basis for further understanding of the pathology associated with SC dysfunction.
Superior Colliculi/physiology* ; Saccades ; Neurons/physiology*

Humans ; Locomotion ; Mesencephalon ; Midbrain Reticular Formation ; Parkinson Disease