Project description:Despite recent clinical observations linking the zona incerta (ZI) to anxiety, little is known about whether and how the ZI processes anxiety. Here, we subject mice to anxious experiences and observe an increase in ZI c-fos–labeled neurons and single-cell calcium activity as well as an efficient effect of ZI infusion of diazepam, a classical anxiolytic drug. We further identify that somatostatin (SOM)–, calretinin (CR)–, and vesicular glutamate transporter-2 (Vglut2)–expressing cells display unique electrophysiological profiles; however, they similarly respond to anxiety-provoking stimuli and to diazepam. Optogenetic manipulations reveal that each of these ZI neuronal populations triggers specific anxiety-related behavioral phenotypes. Activation of SOM-expressing neurons induced anxiety, while photoactivation of CR-positive cells and photoinhibition of Vglut2-expressing neurons produce anxiolysis. Furthermore, activation of CR- and Vglut2-positive cells provokes rearing and jumps, respectively. Our findings provide the first experimental evidence that ZI subpopulations encode and modulate different components of anxiety.
Project description:The zona incerta (ZI) supports diverse behaviors including binge feeding, sleep-wake cycles, nociception, and hunting. Diverse ZI functions can be attributed to its heterogeneous neurochemical characterization, cytoarchitecture, and efferent connections. The ZI is predominantly GABAergic, but we recently identified a subset of medial ZI GABA cells that are marked by the enzyme tyrosine hydroxylase (TH) and produce dopamine (DA). While the role of GABA within the ZI is well studied, less is known about the functions of ZI DA cells. To identify potential roles of ZI DA cells, we further phenotyped them and mapped their efferent fiber projections. We showed that wild-type TH-immunoreactive (-ir) ZI cells did not express somatostatin or calretinin immunoreactivity. We next validated a Th-cre;L10-Egfp mouse line and found that medial Egfp ZI cells were more likely to be TH-ir. We therefore delivered a Cre-dependent virus into the medial ZI of Th-cre or Th-cre;L10-Egfp mice and selected two injection cases for full brain mapping, namely, cases with the lowest and highest colocalization between TH-ir and virally transduced, DsRed-labeled cells, to identify common target sites. Overall, DsRed-labeled fibers were distributed brainwide and were most prominent within the motor-related midbrain (MBmot), notably the periaqueductal gray area and superior colliculus. We also observed numerous DsRed-labeled fibers within the polymodal association cortex-related thalamus (DORpm), like paraventricular thalamic nucleus and nucleus of reunions, that processes external and internal sensory input. Overall, ZI DA cells displayed a similar fiber profile to ZI GABA cells and may integrate sensory input to coordinate motor output at their target sites.
Project description:The zona incerta (ZI) supports diverse behaviors including binge feeding, sleep/wake cycles, nociception, and hunting. This diversity of functions can be attributed to the heterogenous neurochemicals, cytoarchitecture, and efferent connections that characterize the ZI. The ZI is predominantly GABAergic, but we recently identified a subset of medial ZI GABA cells that co-express dopamine (DA), as marked by the enzyme tyrosine hydroxylase (TH). While the role of GABA within the ZI is well studied, little is understood about the function of ZI DA cells. To identify potential roles of ZI DA cells we mapped the efferent fiber projections from Th-cre ZI cells. We first validated a Th-cre;L10-Egfp mouse line and found that medial Egfp ZI cells were more likely to co-express TH-immunoreactivity (TH-ir). We thus delivered a cre-dependent virus into the medial ZI of Th-cre or Th-cre;L10-Egfp mice and selected two injection cases for full brain mapping. We selected the cases with the lowest (17%) and highest (53%) percentage of colocalization between TH-ir and virus transfected cells labelled with DsRed. Overall, DsRed-labelled fibers were observed throughout the brain and were most prominent within motor-related regions of the midbrain (MBmot), notably the periaqueductal grey area and superior colliculus. We also observed considerable DsRed-labelled fibers within the polymodal cortex associated regions of the thalamus (DORpm), including the paraventricular thalamic nucleus and nucleus of reunions. Overall, ZI DA cells displayed a similar connectivity profile to ZI GABA cells, suggesting that ZI DA cells may perform synergistic or opposing functions at the same target sites.
Project description:Dopaminergic (DA) neurons are known to play a key role in controlling behaviors. While DA neurons in other brain regions are extensively characterized, those in zona incerta (ZITH or A13) receive much less attention and their function remains to be defined. Here it is shown that optogenetic stimulation of these neurons elicited intensive self-grooming behaviors and promoted place preference, which can be enhanced by training but cannot be converted into contextual memory. Interestingly, the same stimulation increased DA release to periaqueductal grey (PAG) neurons and local PAG antagonism of DA action reduced the elicited self-grooming. In addition, A13 neurons increased their activity in response to various external stimuli and during natural self-grooming episodes. Finally, monosynaptic retrograde tracing showed that the paraventricular hypothalamus represents one of the major upstream brain regions to A13 neurons. Taken together, these results reveal that A13 neurons are one of the brain sites that promote appetitive self-grooming involving DA release to the PAG.
Project description:Pain and itch are intricately entangled at both circuitry and behavioral levels. Emerging evidence indicates that parvalbumin (PV)-expressing neurons in zona incerta (ZI) are critical for promoting nocifensive behaviors. However, the role of these neurons in itch modulation remains elusive. Herein, by combining FOS immunostaining, fiber photometry, and chemogenetic manipulation, we reveal that ZI PV neurons act as an endogenous negative diencephalic modulator for itch processing. Morphological data showed that both histamine and chloroquine stimuli induced FOS expression in ZI PV neurons. The activation of these neurons was further supported by the increased calcium signal upon scratching behavior evoked by acute itch. Behavioral data further indicated that chemogenetic activation of these neurons reduced scratching behaviors related to histaminergic and non-histaminergic acute itch. Similar neural activity and modulatory role of ZI PV neurons were seen in mice with chronic itch induced by atopic dermatitis. Together, our study provides direct evidence for the role of ZI PV neurons in regulating itch, and identifies a potential target for the remedy of chronic itch.
Project description:The zona incerta (ZI) is involved in various functions and may serve as an integrative node of the circuits for global behavioral modulation. However, the long-range connectivity of different sectors in the mouse ZI has not been comprehensively mapped. Here, we obtained whole-brain images of the input and output connections via fluorescence micro-optical sectioning tomography and viral tracing. The principal regions in the input-output circuits of ZI GABAergic neurons were topologically organized. The 3D distribution of cortical inputs showed rostro-caudal correspondence with different ZI sectors, while the projection fibers from ZI sectors were longitudinally organized in the superior colliculus. Clustering results show that the medial and lateral ZI are two different major functional compartments, and they can be further divided into more subdomains based on projection and input connectivity. This study provides a comprehensive anatomical foundation for understanding how the ZI is involved in integrating different information, conveying motivational states, and modulating global behaviors.
Project description:Multiple populations of wake-promoting neurons have been characterized in mammals, but few sleep-promoting neurons have been identified. Wake-promoting cell types include hypocretin and GABA (γ-aminobutyric-acid)-releasing neurons of the lateral hypothalamus, which promote the transition to wakefulness from non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. Here we show that a subset of GABAergic neurons in the mouse ventral zona incerta, which express the LIM homeodomain factor Lhx6 and are activated by sleep pressure, both directly inhibit wake-active hypocretin and GABAergic cells in the lateral hypothalamus and receive inputs from multiple sleep-wake-regulating neurons. Conditional deletion of Lhx6 from the developing diencephalon leads to decreases in both NREM and REM sleep. Furthermore, selective activation and inhibition of Lhx6-positive neurons in the ventral zona incerta bidirectionally regulate sleep time in adult mice, in part through hypocretin-dependent mechanisms. These studies identify a GABAergic subpopulation of neurons in the ventral zona incerta that promote sleep.
Project description:The ability to adjust defensive behavior is critical for animal survival in dynamic environments. However, neural circuits underlying the modulation of innate defensive behavior remain not well-understood. In particular, environmental threats are commonly associated with cues of multiple sensory modalities. It remains to be investigated how these modalities interact to shape defensive behavior. In this study, we report that auditory-induced defensive flight behavior can be facilitated by somatosensory input in mice. This cross-modality modulation of defensive behavior is mediated by the projection from the primary somatosensory cortex (SSp) to the ventral sector of zona incerta (ZIv). Parvalbumin (PV)-positive neurons in ZIv, receiving direct input from SSp, mediate the enhancement of the flight behavior via their projections to the medial posterior complex of thalamus (POm). Thus, defensive flight can be enhanced in a somatosensory context-dependent manner via recruiting PV neurons in ZIv, which may be important for increasing survival of prey animals.
Project description:To determine how a waking brain falls asleep researchers have monitored and manipulated activity of neurons and glia in various brain regions. While imaging Gamma-Aminobutyric Acid (GABA) neurons in the zona incerta (ZI) we found a subgroup that anticipates onset of NREM sleep (Blanco-Centurion C, Luo S, Vidal-Ortiz A, Swank C, Shiromani PJ. Activity of a subset of vesicular GABA-transporter neurons in the ventral ZI anticipates sleep onset. Sleep. 2021;44(6):zsaa268. doi:10.1093/sleep/zsaa268.). To differentiate the GABA subtype we now image and optogenetically manipulate the ZI neurons containing the transcription factor, Lhx6. In the first study, Lhx6-cre mice (n = 5; female = 4) were given rAAV-DJ-EF1a-DIO-GCaMP6M into the ZI (isofluorane anesthesia), a GRIN lens implanted, and 21days later sleep and fluorescence in individual Lhx6 neurons were recorded for 4 hours. Calcium fluorescence was detected in 132 neurons. 45.5% of the Lhx6 neurons were REM-max; 30.3% were wake-max; 11.4% were wake + REM max; 9% were NREM-max; and 3.8% had no change. The NREM-max group of neurons fluoresced 30 seconds ahead of sleep onset. The second study tested the effects of unilateral optogenetic stimulation of the ZI Lhx6 neurons (n = 14 mice) (AAV5-Syn-FLEX-rc[ChrimsonR-tdTomato]. Stimulation at 1 and 5 Hz (1 minute on- 4 minutes off) significantly increased percent REM sleep during the 4 hours stimulation period (last half of day cycle). The typical experimental approach is to stimulate neurons in both hemispheres, but here we found that low-frequency stimulation of ZI Lhx6 neurons in one hemisphere is sufficient to shift states of consciousness. Detailed mapping combined with mechanistic testing is necessary to identify local nodes that can shift the brain between wake-sleep states.
Project description:Parkinson's disease (PD) is the second most common and fastest-growing neurodegenerative disorder. In recent years, it has been recognized that neurotransmitters other than dopamine and neuronal systems outside the basal ganglia are also related to PD pathogenesis. However, little is known about whether and how the caudal zona incerta (ZIc) regulates parkinsonian motor symptoms. Here, we showed that specific glutamatergic but not GABAergic ZIcVgluT2 neurons regulated these symptoms. ZIcVgluT2 neuronal activation induced time-locked parkinsonian motor symptoms. In mouse models of PD, the ZIcVgluT2 neurons were hyperactive and inhibition of their activity ameliorated the motor deficits. ZIcVgluT2 neurons monosynaptically projected to the substantia nigra pars reticulata. Incerta-nigral circuit activation induced parkinsonian motor symptoms. Together, our findings provide a direct link between the ZIc, its glutamatergic neurons, and parkinsonian motor symptoms for the first time, help to better understand the mechanisms of PD, and supply a new important potential therapeutic target for PD.