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Open Access Publications from the University of California

Scholarly Works (11 results)

  • Thesis
  • Peer Reviewed
UC Berkeley Electronic Theses and Dissertations (2018)

Sleep is a fundamental behavior in the animal kingdom. It is essential for optimal cognition,

general health, immune function and neuronal plasticity. Irregular or insufficient sleep may

cause emotional disturbances, abnormal homeostasis of physiological functions. About 30%

adults in the US suffered from insomnia. Therefore, understanding of the sleep‐wake circuit will

contribute to the cure of not only sleep disorders, but also other psychiatric diseases. A crucial

step in understanding the neural circuits controlling sleep is to identify the sleep neurons. In my

thesis, I used transgenic Cre mouse lines, virus‐mediated circuit tracing, and optogenetic

manipulation to identify the sleep‐promoting neurons and dissect the neural circuits for

controlling sleep and arousal.

In chapter 2: The basal forebrain (BF) contains a spatially intermingled diverse population of

neurons that play key roles in multiple brain functions, including sleep‐wake regulation,

attention, and learning/memory. For sleep‐wake regulation, the cholinergic, glutamatergic, and

parvalbumin‐expressing (PV) GABAergic neurons have been shown to promote wakefulness,

whereas the somatostatin‐expressing (SOM) GABAergic neurons promote NREM sleep. To

understand how these cell types in the same area have different functions in sleep‐wake

regulation, we used rabies virus ‐mediated monosynaptic retrograde tracing to label the inputs

and adeno‐associated virus to trace axonal projections. We identified numerous brain areas

connected to the BF. These results reveal the long‐range wiring diagram of the BF circuit with

highly convergent inputs and divergent outputs and point to both functional commonality and

specialization of different BF cell types.

In chapter3: We identified the neurotensin (NTS) neurons in the preoptic area, posterior

thalamus (pTh), and ventrolateral periaqueductal gray (vlPAG) as NREM sleep‐promoting

neurons based on optogenetic manipulation. Using rabies virus‐mediated monosynaptic

retrograde tracing combined with fluorescent in situ hybridization (FISH) experiment, we also

showed that cholecystokinin (CCK) and calcitonin gene‐related peptide alpha (Calca) neurons in

the EW (CCKEW), and NTS neurons in the vlPAG (NTSvlPAG) form reciprocal connections to each

other. These cell types may cooperate to promote NREM sleep.

    Cover page: Neuronal Circuits of NREM Sleep Control in the Basal Forebrain and Midbrain
    • Article
    • Peer Reviewed
    UC Berkeley Previously Published Works (2018)
    Rapid eye movement (REM) and non-REM (NREM) sleep are controlled by specific neuronal circuits. Here we show that galanin-expressing GABAergic neurons in the dorsomedial hypothalamus (DMH) comprise separate subpopulations with opposing effects on REM versus NREM sleep. Microendoscopic calcium imaging revealed diverse sleep-wake activity of DMH GABAergic neurons, but the galanin-expressing subset falls into two distinct groups, either selectively activated (REM-on) or suppressed (REM-off) during REM sleep. Retrogradely labeled, preoptic area (POA)-projecting galaninergic neurons are REM-off, whereas the raphe pallidus (RPA)-projecting neurons are primarily REM-on. Bidirectional optogenetic manipulations showed that the POA-projecting neurons promote NREM sleep and suppress REM sleep, while the RPA-projecting neurons have the opposite effects. Thus, REM/NREM switch is regulated antagonistically by DMH galaninergic neurons with intermingled cell bodies but distinct axon projections.
      Cover page: A Hypothalamic Switch for REM and Non-REM Sleep
      • Article
      • Peer Reviewed
      UC Berkeley Previously Published Works (2019)
      A crucial step in understanding the sleep-control mechanism is to identify sleep neurons. Through systematic anatomical screening followed by functional testing, we identified two sleep-promoting neuronal populations along a thalamo-amygdala pathway, both expressing neurotensin (NTS). Rabies-mediated monosynaptic retrograde tracing identified the central nucleus of amygdala (CeA) as a major source of GABAergic inputs to multiple wake-promoting populations; gene profiling revealed NTS as a prominent marker for these CeA neurons. Optogenetic activation and inactivation of NTS-expressing CeA neurons promoted and suppressed non-REM (NREM) sleep, respectively, and optrode recording showed they are sleep active. Further tracing showed that CeA GABAergic NTS neurons are innervated by glutamatergic NTS neurons in a posterior thalamic region, which also promote NREM sleep. CRISPR/Cas9-mediated NTS knockdown in either the thalamic or CeA neurons greatly reduced their sleep-promoting effect. These results reveal a novel thalamo-amygdala circuit for sleep generation in which NTS signaling is essential for both the upstream glutamatergic and downstream GABAergic neurons.
        Cover page: Sleep Regulation by Neurotensinergic Neurons in a Thalamo-Amygdala Circuit
        • Article
        • Peer Reviewed
        UC Berkeley Previously Published Works (2014)
        Top-down modulation of sensory processing allows the animal to select inputs most relevant to current tasks. We found that the cingulate (Cg) region of the mouse frontal cortex powerfully influences sensory processing in the primary visual cortex (V1) through long-range projections that activate local γ-aminobutyric acid-ergic (GABAergic) circuits. Optogenetic activation of Cg neurons enhanced V1 neuron responses and improved visual discrimination. Focal activation of Cg axons in V1 caused a response increase at the activation site but a decrease at nearby locations (center-surround modulation). Whereas somatostatin-positive GABAergic interneurons contributed preferentially to surround suppression, vasoactive intestinal peptide-positive interneurons were crucial for center facilitation. Long-range corticocortical projections thus act through local microcircuits to exert spatially specific top-down modulation of sensory processing.
          • Article
          • Peer Reviewed
          LBL Publications (2016)
          The basal forebrain (BF) plays key roles in multiple brain functions, including sleep-wake regulation, attention, and learning/memory, but the long-range connections mediating these functions remain poorly characterized. Here we performed whole-brain mapping of both inputs and outputs of four BF cell types - cholinergic, glutamatergic, and parvalbumin-positive (PV+) and somatostatin-positive (SOM+) GABAergic neurons - in the mouse brain. Using rabies virus -mediated monosynaptic retrograde tracing to label the inputs and adeno-associated virus to trace axonal projections, we identified numerous brain areas connected to the BF. The inputs to different cell types were qualitatively similar, but the output projections showed marked differences. The connections to glutamatergic and SOM+ neurons were strongly reciprocal, while those to cholinergic and PV+ neurons were more unidirectional. These results reveal the long-range wiring diagram of the BF circuit with highly convergent inputs and divergent outputs and point to both functional commonality and specialization of different BF cell types.
            Cover page: Cell type-specific long-range connections of basal forebrain circuit.
            • Article
            • Peer Reviewed
            UC Berkeley Previously Published Works (2016)
            Long-range projections from the frontal cortex are known to modulate sensory processing in multiple modalities. Although the mouse has become an increasingly important animal model for studying the circuit basis of behavior, the functional organization of its frontal cortical long-range connectivity remains poorly characterized. Here we used virus-assisted circuit mapping to identify the brain networks for top-down modulation of visual, somatosensory and auditory processing. The visual cortex is reciprocally connected to the anterior cingulate area, whereas the somatosensory and auditory cortices are connected to the primary and secondary motor cortices. Anterograde and retrograde tracing identified the cortical and subcortical structures belonging to each network. Furthermore, using new viral techniques to target subpopulations of frontal neurons projecting to the visual cortex versus the superior colliculus, we identified two distinct subnetworks within the visual network. These findings provide an anatomical foundation for understanding the brain mechanisms underlying top-down control of behavior.
              Cover page: Organization of long-range inputs and outputs of frontal cortex for top-down control.
              • Article
              • Peer Reviewed
              UC Berkeley Previously Published Works (2016)
              The basal forebrain (BF) plays key roles in multiple brain functions, including sleep-wake regulation, attention, and learning/memory, but the long-range connections mediating these functions remain poorly characterized. Here we performed whole-brain mapping of both inputs and outputs of four BF cell types - cholinergic, glutamatergic, and parvalbumin-positive (PV+) and somatostatin-positive (SOM+) GABAergic neurons - in the mouse brain. Using rabies virus -mediated monosynaptic retrograde tracing to label the inputs and adeno-associated virus to trace axonal projections, we identified numerous brain areas connected to the BF. The inputs to different cell types were qualitatively similar, but the output projections showed marked differences. The connections to glutamatergic and SOM+ neurons were strongly reciprocal, while those to cholinergic and PV+ neurons were more unidirectional. These results reveal the long-range wiring diagram of the BF circuit with highly convergent inputs and divergent outputs and point to both functional commonality and specialization of different BF cell types.
                • Article
                • Peer Reviewed
                UC Berkeley Previously Published Works (2015)
                The mammalian basal forebrain (BF) has important roles in controlling sleep and wakefulness, but the underlying neural circuit remains poorly understood. We examined the BF circuit by recording and optogenetically perturbing the activity of four genetically defined cell types across sleep-wake cycles and by comprehensively mapping their synaptic connections. Recordings from channelrhodopsin-2 (ChR2)-tagged neurons revealed that three BF cell types, cholinergic, glutamatergic and parvalbumin-positive (PV+) GABAergic neurons, were more active during wakefulness and rapid eye movement (REM) sleep (wake/REM active) than during non-REM (NREM) sleep, and activation of each cell type rapidly induced wakefulness. By contrast, activation of somatostatin-positive (SOM+) GABAergic neurons promoted NREM sleep, although only some of them were NREM active. Synaptically, the wake-promoting neurons were organized hierarchically by glutamatergic→cholinergic→PV+ neuron excitatory connections, and they all received inhibition from SOM+ neurons. Together, these findings reveal the basic organization of the BF circuit for sleep-wake control.
                  • Article
                  • Peer Reviewed
                  UC Berkeley Previously Published Works (2021)
                  Microglial cells are known to contribute to brain development and behaviors, but the mechanisms behind such functions are not fully understood. Here, we show that mice deficient in inflammasome regulators, including caspase-1 (Casp1), NLR family pyrin domain containing 3 (Nlrp3), IL-1 receptor (Il-1r), and gasdermin D (Gsdmd), exhibit behavior abnormalities characterized by hyperactivity and low anxiety levels. Furthermore, we found that expression of Casp1 in CX3CR1+ myeloid cells, which includes microglia, is required for preventing these abnormal behaviors. Through tissue clearing and 3D imaging, we discovered that small numbers of Cx3cr1-GFP+ fetal microglial cells formed clusters and underwent lytic cell death in the primitive thalamus and striatum between embryonic day (E)12.5 and E14.5. This lytic cell death was diminished in Casp1-deficient mice. Further analysis of the microglial clusters showed the presence of Pax6+ neural progenitor cells (NPCs); thus, we hypothesized that microglial lytic cell death is important for proper neuronal development. Indeed, increased numbers of neurons were observed in the thalamic subset in adult Casp1-/- brains. Finally, injection of drug inhibitors of NLRP3 and CASP1 into wild-type (WT) pregnant mice from E12.5 to E14.5, the period when lytic cell death was detected, was sufficient to induce atypical behaviors in offspring. Taken together, our data suggests that the inflammasome cascade in microglia is important for regulating neuronal development and normal behaviors, and that genetic or pharmacological inhibition of this pathway can induce atypical behaviors in mice.
                    Cover page: Lytic Cell Death in Specific Microglial Subsets Is Required for Preventing Atypical Behavior in Mice
                    • Article
                    • Peer Reviewed
                    UC Berkeley Previously Published Works (2016)
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