Ellen J. Hess - US grants

The general goal of this research is to understand the etiology of human neurologic disorders by using animal models to identify the abnormal genetic, molecular and cellular pathways that finally result in the clinical manifestation of the mutation. Mutant strains of mice are proving to be useful animal models in determining the mechanisms underlying inherited disorders of the nervous system. The tottering (tg) mouse mutant has been extensively studied as a mouse model of epilepsy. These mice exhibit a triad of neuropathologies including spike and wave discharges, myoclonus and ataxia. The tg mutation is also associated with two distinct cellular abnormalities: hyperarborization of noradrenergic fibers arising from the locus ceruleus and aberrant expression of tyrosine hydroxylase (TH) in cerebellar Purkinje cells. However, the role of these cellular anomalies in the expression of the abnormal phenotype is not yet clear nor has the tg gene yet been identified. The goal of this proposal is to trace the mutation from gene to behavior to begin to piece together the series of molecular and cellular events that ultimately give rise to the expression of the tottering phenotype. The specific aims of this proposal are: l) to isolate the tg gene. The tottering mouse phenotype provides few clues to the specific mutation. However, our preliminary data suggest specific brain regions, developmental timepoints and an exact chromosome location for the tg gene, making identification of this gene possible for the first time. 2) to identify the neuroanatomical substrates of myoclonus in tottering mice. We have recently discovered how to induce myoclonus in tottering mice. By using markers of neuronal activation during a tottering mouse myoclonic episode, these experiments will determine if there is an obligatory temporal and anatomical progression of neuronal recruitment that occurs in the expression of myoclonus. 3) to determine the precise relationship of noradrenergic innervation to the expression and development of the tottering phenotype. Although the noradrenergic hyperinnervation arising from the tottering mouse LC contributes to the spike and wave discharges, the effect of this hyperarborization on the expression and development of myoclonus, ataxia and Purkinje cell TH expression has not been studied. The results of this proposal will furnish new insights into the disease process resulting in the tottering mouse phenotype which may be generalized to the genesis and maintenance of epilepsies and/or ataxia in humans.

[unreadable] DESCRIPTION (provided by applicant): Pathologic hyperactivity is observed in several neurologic disorders including Attention Deficit Hyperactivity Disorder (ADHD) and Tourette's syndrome (TS). The general goal of this research is to understand the etiology of pathologic hyperactivity by using a well-defined animal model to identify abnormal cellular events that ultimately result in the clinical manifestation of hyperactivity. We have identified the mouse mutant coloboma as a novel animal model of hyperactivity. These mice are profoundly hyperactive with locomotor activity exceeding 3 times that of their control littermates. We have demonstrated that the hyperactivity expressed by coloboma mice is clearly the result of a deletion of the Snap gene. This gene encodes SNAP-25, a neuron-specific protein that is a component of the machinery essential for docking and holding synaptic vesicles at the presynaptic membrane in readiness for Ca 2+ triggered neurotransmitter exocytosis. Although SNAP-25 is expressed in all neurons, our experiments have focused on catecholamine (dys) regulation because catecholamines are known to regulate hyperactivity in both man and animals. We have found that defects in catecholamine regulation are specific to the striatum and nucleus accumbens; norepinephrine (NE) concentrations are significantly increased while dopamine (DA) utilization is decreased. NE and DA regulation is normal in all other brain regions. The increase in NE likely contributes to the expression of locomotor hyperactivity in these mice as depletion of NE ameliorates the coloboma mouse hyperactivity. These results provide strong evidence for the hypothesis that, in this pathologic state, NE may modulate locomotor hyperactivity. The aberrant regulation of NE in this mouse model is especially relevant, as abnormalities in NE have been identified in ADHD and TS. [unreadable] [unreadable]

The general goal of this research is to understand the etiology of human neurologic disorders by using animal models to identify the abnormal genetic, molecular and cellular pathways that finally result in the clinical manifestation of the mutation. Mutant strains of mice are proving to be useful animal models in determining the mechanisms underlying inherited disorders of the nervous system. The tottering (tg) mouse mutant has been extensively studied as a mouse model of epilepsy. These mice exhibit a triad of neuropathologies including spike and wave discharges, myoclonus and ataxia. The tg mutation is also associated with two distinct cellular abnormalities: hyperarborization of noradrenergic fibers arising from the locus ceruleus and aberrant expression of tyrosine hydroxylase (TH) in cerebellar Purkinje cells. However, the role of these cellular anomalies in the expression of the abnormal phenotype is not yet clear nor has the tg gene yet been identified. The goal of this proposal is to trace the mutation from gene to behavior to begin to piece together the series of molecular and cellular events that ultimately give rise to the expression of the tottering phenotype. The specific aims of this proposal are: l) to isolate the tg gene. The tottering mouse phenotype provides few clues to the specific mutation. However, our preliminary data suggest specific brain regions, developmental timepoints and an exact chromosome location for the tg gene, making identification of this gene possible for the first time. 2) to identify the neuroanatomical substrates of myoclonus in tottering mice. We have recently discovered how to induce myoclonus in tottering mice. By using markers of neuronal activation during a tottering mouse myoclonic episode, these experiments will determine if there is an obligatory temporal and anatomical progression of neuronal recruitment that occurs in the expression of myoclonus. 3) to determine the precise relationship of noradrenergic innervation to the expression and development of the tottering phenotype. Although the noradrenergic hyperinnervation arising from the tottering mouse LC contributes to the spike and wave discharges, the effect of this hyperarborization on the expression and development of myoclonus, ataxia and Purkinje cell TH expression has not been studied. The results of this proposal will furnish new insights into the disease process resulting in the tottering mouse phenotype which may be generalized to the genesis and maintenance of epilepsies and/or ataxia in humans.

phenotype; disease /disorder model; myoclonus epilepsy; gene mutation; laboratory mouse; neurogenetics; tyrosine 3 monooxygenase; neuropharmacology; locus coeruleus; cerebellar Purkinje cell; gene expression; neuroanatomy; ataxia; complementary DNA; artificial chromosomes; molecular cloning;

[unreadable] DESCRIPTION (provided by applicant): Episodic neurological disorders are characterized by attacks of debilitating symptoms interspersed with periods of relatively normal function. Although the symptoms can be diverse, including migraine headache, epilepsy, paralysis, ataxia, and dyskinesia, there are marked similarities in both the genetic etiology and the factors capable of triggering attacks in episodic disorders. Many episodic disorders are associated with ion channel mutations. Further, regardless of the class of ion channelopathy or the expressed symptoms, the precipitants of attacks are most commonly psychological, physical or chemical stressors, suggesting the existence of a common mechanism for the initiation of the attacks. There is little understanding of the mechanisms by which these triggers precipitate neurological dysfunction in individuals who are otherwise normal between attacks. Our approach to this problem is to use a rare monogenic disorder as a model system. because understanding pathogenesis in a monogenic episodic disorder will likely provide insight into genetically complex episodic disorders such as migraine headache and idiopathic epilepsy. We have identified episodic ataxia type 2 (EA2), as a leading candidate for modeling this class of disorders in mice. EA2 is caused by mutations in the CACNA1A gene, which encodes the pore-forming a12.1 subunit of Cav2.1 (P/Q-type) voltage-gated calcium channels. This disorder is particularly amenable for modeling because there is already a wealth of basic information on which to build, including an enormous body of work describing normal and mutant Cav2.1 channel properties in vitro. Individuals with episodic ataxia type 2 experience paroxysmal attacks of migraine, ataxia, and other neurological signs that are triggered by emotional stress, exercise, caffeine or ethanol. Although the mutations in CACNA1A were first identified in 1996, the pathogenic mechanisms are still unknown. Functional expression studies of EA2 mutations in heterologous systems demonstrate reduced Cav2.1 currents, as expected. However, there is evidence for both haploinsufficiency and dominant negative effects of the mutant channel, demonstrating that even this most basic of questions requires expression of the mutants in a native in vivo system. Work in both cultured neurons and mouse mutants also demonstrates that an appreciation of the biophysical properties of the mutant channel in vitro is not likely to provide a comprehensive understanding of the phenotype because compensatory processes in neurons in vivo may also contribute. These results demonstrate the need for a behaviorally intact animal model to fully appreciate disease processes. Therefore, we will develop and characterize a knockin mouse bearing an EA2 mutation. The specific aims of this proposal are 1) To develop and characterize a knockin mouse model of EA2. 2) To behaviorally characterize the EA2 knockin mice. The development of a mouse model will place us in an excellent position to examine pathophysiology and provide insight into human disease. Episodic neurological disorders are characterized by attacks of debilitating symptoms, including migraine headache, epilepsy, paralysis, ataxia, and dyskinesia, interspersed with periods of relatively normal function. There is little understanding of the pathophysiological mechanisms that triggers neurological dysfunction. Therefore, we will develop and characterize a knockin mouse bearing a human mutation for episodic ataxia, a rare monogenic disorder that may provide insight into genetically complex episodic disorders such as migraine headache and idiopathic epilepsy. [unreadable] [unreadable] [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): Dystonia is the third most common movement disorder, after essential tremor and Parkinson disease, with a prevalence of ~330 per million. Dystonia is broadly characterized by simultaneous and sometimes sustained contractions of agonist and antagonist muscles. These co-contractions result in twisting movements and postures that have a wide range of speed, amplitude and rhythmicity that varies among patients. The general goal of our research is to understand the pathophysiology of dystonia. Unlike Parkinson disease or Huntington disease where neurodegeneration provides clues to the pathogenesis of the movement disorder, idiopathic dystonia is a functional movement disorder without obvious markers or cell death to help define pathophysiology. Despite a strong clinico-pathological correlation between the basal ganglia and dystonia, there is little understanding of the underlying neuronal dysfunction. Moreover, the few animal models of dystonia associated with basal ganglia function are of limited value because the pathophysiology is inconsistent with abnormalities in human dystonias. Our approach to this problem is to model a monogenic dystonic disorder to provide broad insight into pathophysiological mechanisms. We have identified L-DOPA responsive dystonia (DRD), as a leading candidate for modeling dystonia associated with basal ganglia dysfunction. DRD is caused by mutations in genes encoding either GTP cyclohydrolase or tyrosine hydroxylase (TH) and is characterized by early onset generalized dystonia that is ameliorated after administration of low doses of L-DOPA, the metabolic precursor of dopamine. DRD caused by mutations in TH is particularly amenable for modeling because there is already a wealth of basic information on which to build, including an enormous body of work describing normal TH function and dopaminergic regulation of motor control. Therefore, we will develop and characterize a knockin mouse bearing a human mutation in TH that is associated with DRD. Therefore, we will develop and characterize a knockin mouse bearing an EA2 mutation. The specific aims of this proposal are 1) to develop and characterize a knockin mouse model of DRD. 2) To behaviorally characterize the DRD knockin mice. Development and characterization of an animal model exhibiting basal ganglia dysfunction that is mechanistically faithful and reliably reproducible is critical to understanding pathophysiology in dystonia and essential for developing novel therapeutics. Dystonia is the third most common movement disorder with a prevalence of ~330 per million. Dystonia is broadly characterized by simultaneous and sometimes sustained contractions of agonist and antagonist muscles. There is little understanding of the pathophysiological mechanisms underlying dystonia. Therefore, we will develop and characterize a knockin mouse bearing a human mutation that causes L-DOPA-responsive dystonia to provide insight into general pathomechanisms underlying dystonia. [unreadable] [unreadable] [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): Dystonia is a common neurological disorder broadly characterized by sustained simultaneous contractions of agonist and antagonist muscles. The general goal of our research is to understand the pathophysiology of dystonia. While the focus of dystonia research has been on the basal ganglia, the massive convergence of information required to orchestrate the firing of motoneurons suggests that abnormalities in other motor systems, including the cerebellum, could result in such distorted signaling. Given that lesions of the basal ganglia are identified in some dystonic patients while abnormal activity is observed in the cerebellum of other patients, our experimental approach incorporates the concept that many different brain regions contribute to the expression of dystonia. To understand the pathophysiology principles of dystonia, we have developed 3 mouse models of generalized dystonia in the last funding cycle. These models include the tottering mouse mutant, dystonia induced by the L-type calcium channel agonists and dystonia induced by microinjection of low dose kainate in the cerebellum. With the initial characterization of these models complete, we are poised to determine the anatomical, neurochemical and physiological substrates of dystonia. Our strategy is to test several models of dystonia to identify general pathophysiological principles. The specific aims are: 1) To determine the anatomical substrates of dystonia by examining the effects of lesions. 2) To identify the neurochemical substrates of dystonia using drug challenge. 3) To characterize Purkinje cell firing patterns in dystonia using multielectrode recording in dystonia. 4) To determine the electromyographic (EMG) correlates of dystonia in the mouse models. The experiments in this proposal apply anatomical, physiological and behavioral techniques to determine the neurobiology of dystonia. Unlike Parkinson disease or Huntington disease where cell death provides clues to the pathogenesis of the movement disorder, dystonia is a functional movement disorder with no obvious markers to help define pathophysiology. With the development of 3 different mouse models of dystonia, we are in an excellent position to examine pathophysiology and provide insight into human disease. Public health relevance: Dystonia is the third most common movement disorder, but current therapies are largely unsatisfactory. The goal is to understand the pathophysiology of dystonia to direct novel treatments. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Dystonia is characterized by excessive involuntary muscle contractions that cause abnormal postures and twisting movements. Current treatments for dystonia are largely unsatisfactory or palliative. Small molecule drugs are ineffective in most patients. Botulinum toxin is effective but requires injection into affected muscles, limiting its ue to the treatment of dystonias that affect a small number of muscles. Deep brain stimulation (DBS) of the internal globus pallidus is another treatment option. Some patients, particularly those suffering from primary generalized dystonia experience tremendous benefits from pallidal DBS. However, many other patients, particularly those with secondary dystonias, experience little or no improvement, demonstrating a need for the identification and exploration of new treatment targets. Strong evidence implicates cerebellar abnormalities in dystonia and supports the idea that electrical stimulation of the cerebellum is an effective treatment for dystonia. Autopsy studies established a link between cervical dystonia and tumors of the cerebellum. Further, abnormal activity of the cerebellum is observed in many different forms of dystonia additionally, some cerebral palsy patients, who also often suffer from dystonia in addition to spasticity, have experienced improvement after cerebellar electrical stimulation. However, there are currently no studies examining the use of cerebellar stimulation in dystonia per se. Animal studies demonstrate that cerebellar abnormalities can cause dystonia. Abnormal cerebellar activity is observed in mouse and rat models of dystonia. In rat and mouse models, ablation of the cerebellum ameliorates dystonia. The effects of cerebellar stimulation have not yet been explored in animal models to test the idea that dystonia can be ameliorated using the non-ablative approach of electrical stimulation to interrupt abnormal signaling. Although cerebellar stimulation has been used in humans for decades, the use of cerebellar stimulation for the treatment of dystonia is surprisingly limited despite the strong evidence linking cerebellar dysfunction to dystonia in both human and animal studies. This proposal will systematically examine cerebellar stimulation for the treatment of dystonia in mouse models as preclinical proof-of-concept. The specific aims of this proposal are: Aim 1. To determine parameters of cerebellar stimulation that ameliorates dystonia. The effects of methodically varying stimulation parameters, including location, frequency, and amplitude and pulse width on dystonic and baseline activity are assessed in alert unrestrained mouse models of dystonia. Aim 2. to map the anatomical extent of stimulation. Because c-fos expression is routinely used to map electrical stimulation in brain, we will use the fos reporter TetTag mice to map extent of cerebellar stimulation. The success of this proposal will provide preclinical evidence to support an exploratory clinical study in humans for the use of cerebellar stimulation as a treatment for dystonia.

? DESCRIPTION (provided by applicant): Dystonia is characterized by involuntary muscle contractions that cause debilitating twisting movements and postures. Abnormal dopamine (DA) neurotransmission is consistently observed across many different forms of dystonia, but the DA defects that give rise to dystonia are poorly understood. L-DOPA-responsive dystonia (DRD) is considered a prototype disorder for understanding how abnormal DA neurotransmission evokes dystonia. DRD is characterized by childhood onset dystonia with diurnal fluctuation whereby symptoms worsen throughout the course of the day. The distinguishing feature of DRD is the dramatic improvement in symptoms after restoration of DA signaling with L-DOPA or DA agonists. Indeed, DRD is caused by mutations in genes critical for DA synthesis, including tyrosine hydroxylase (TH). DRD-causing TH mutations are associated with some residual TH activity whereas mutations that abolish TH activity cause childhood parkinsonism suggesting that TH activity and [DA] are critical determinants in the development of dystonia. However, the nature of the DA signaling dysfunction that gives rise to dystonia is unknown. To address this gap in our knowledge, we generated a knockin mouse bearing the human DRD-causing Q381K mutation in TH (DRD mice). Like the human disorder, DRD mice display reduced TH activity, a reduction in [DA], dystonic movements that worsen throughout the course of the active period and improvement in the dystonia in response to L-DOPA. Thus, DRD mice exhibit the core neurochemical and symptomatic features of human DRD, thereby providing us with the unprecedented opportunity to dissect the mechanisms underlying DRD from gene to behavior. Our preliminary data demonstrate that the dystonia is mediated by [DA] that is <1% of normal. A similar reduction in presynaptic DA in adults would cause parkinsonism. Therefore, divergent postsynaptic responses likely account for the differences in the neurological consequences of reduced DA transmission between Parkinson's disease (PD) and dystonia. Indeed, our preliminary data demonstrate D1R supersensitivity, hyperexcitability of medium spiny neurons (MSNs), a reduction in MSN dendrite number and abnormal corticostriatal innervation. Therefore, we will test the hypothesis that early life DA deficiency in combination with (mal)adaptive postsynaptic responses gives rise to dystonia by using a multidisciplinary approach to examine the pre- and postsynaptic consequences of reduced DA transmission associated with dystonia. The Specific Aims are: 1. To elucidate the relationship between monoamine metabolism and the severity of dystonia. 2. To determine the DA receptor subtype(s) and signaling defects that contribute to the dystonia. 3. To delineate alterations in th intrinsic and synaptic properties of D1 and D2R-expressing MSNs. 4. To examine the dendritic morphology and ultrastructural changes in corticostriatal synapses onto D1R and D2R-expressing MSNs in response to early-life DA deprivation in DRD mice.

Dystonia is characterized by involuntary muscle contractions that cause debilitating twisting movements and postures. Striatal dysfunction has been implicated in many forms of dystonia, including idiopathic dystonias, inherited dystonias and iatrogenic dystonias. The vast majority of neurons in the striatum are GABAergic spiny projection neurons (SPNs). SPNs express either D1 dopamine receptors (D1Rs) or D2 dopamine receptors (D2Rs). D1Rs are expressed on direct pathway SPNs (dSPNs) that project to the GPi to promote movement. D2Rs are expressed on indirect pathway SPNs (iSPNs) that project to the external pallidum (GPe) to inhibit movement. Convergent results from genetic, imaging and physiological studies in patients suggest that abnormalities of both dSPNs and iSPNs contribute to the expression of dystonia. Despite the overwhelming evidence implicating striatal dysfunction in dystonia, the precise nature of the striatal defects that give rise to dystonia are not known. Research focused on understanding striatal dysfunction in dystonia has been stymied by the lack of animal models with dystonic movements that are specifically associated with striatal dysfunction. To overcome this obstacle, we recently generated a knockin mouse model of DOPA-responsive dystonia (DRD). The DRD mouse strain carries the human DRD-causing Q381K mutation in tyrosine hydroxylase (ThDRD; DRD mice). Like the human disorder, DRD mice exhibit dystonic movements that that improve in response to L-DOPA administration. Notably, striatal DA neurotransmission, including abnormal D1R and D2R signaling, plays a central role in the expression of dystonia. Thus, this novel mouse model provides an unparalleled opportunity to understand the molecular mechanisms underlying dSPN and iSPN dysfunction in dystonia. The Specific Aim is to identify cell-type specific changes in the translatome of dSPNs and iSPNs in DRD mice. In light of how little is known about striatal dysfunction in dystonia, a hypothesis-generating approach that provides a comprehensive account of dSPN and iSPN cell-type specific molecular adaptations is needed to fully decipher the pathogenesis of dystonia. However, a major challenge to understanding cell-type specific molecular changes in dystonia is the complexity of striatal anatomy. Because dSPNs and iSPNs are intermingled throughout the striatum, traditional whole tissue RNA-seq is not useful for delineating cell-type specific abnormalities. Therefore, we will isolate translating ribosomes (Translating Ribosome Affinity Purification (TRAP)) from genetically identified dSPNs and iSPNs in normal and DRD mice to identify abnormally regulated processes and pathways associated with dystonia. This approach will provide unprecedented insight into the cell-type specific molecular abnormalities in dystonia.

Dystonia is characterized by involuntary muscle contractions that cause twisting movements and postures. Although basal ganglia dysfunction is consistently implicated across many forms of dystonia, the underlying pathophysiology is unknown. The major input structure of the basal ganglia is the striatum. The vast majority of neurons in the striatum are GABAergic spiny projection neurons (SPNs). Direct pathway SPNs (dSPNs) project to the internal pallidum (GPi) to promote movement. Indirect pathway SPNs (iSPNs) project to the external pallidum (GPe) to inhibit movement. Although dSPNs and dSPNs are largely segregated into separate pathways, they act in concert and within ensembles of coactivity to select and refine movements. In dystonia patients, this coordinated activity appears to be disrupted as microelectrode recordings in dystonia patients reveal abnormal activity in both GPi and GPe. Although these results implicate abnormal activity in both dSPNs and iSPNs, the abnormal patterns of striatal activity that mediate dystonia are unknown. Several challenges have stymied our ability to understand the abnormal neural code underlying dystonia. First, the information obtained from microelectrode recording in patients is, by necessity, quite limited. Second, because dystonia is induced by movement, recordings must be made in awake unrestrained subjects to obtain authentic results. Third, to meaningfully understand striatal pathophysiology, it is necessary to distinguish between dSPNs and iSPNs, which is challenging to accomplish using microelectrode recordings in vivo because these two distinct cells types are intermingled within the striatum. With the recent development of lightweight miniature fluorescence microscopes that can be used to image the activity of genetically-identified SPNs in freely moving mice, we can overcome these obstacles to understand the physiological substrates of dystonia. For the first experiments to reveal abnormal patterns of striatal activity in dystonia, we will use a knockin mouse model of DOPA-responsive dystonia (DRD) in which the striatum is known to play a central role in mediating the dystonia. In fact, both dSPN and iSPN signaling is disrupted in these mice. Thus, we now have an unprecedented opportunity to elucidate the neural code of dystonia for the first time. The Specific Aim is to identify abnormal patterns of striatal activity in dystonia. We will test the hypothesis that dystonia is mediated by abnormal neuronal activity and degraded ensemble activity of dSPNs and iSPNs by performing in vivo Ca2+ imaging in freely moving normal or DRD mice that selectively express the GCaMP6f calcium indicator in either dSPNs or iSPNs. Abnormal firing patterns including the degree of spatial clustering of coactive neurons will be assessed using both well-established approaches and a novel analysis of population dynamics using a machine learning algorithm that we recently developed to identify and predict dystonia-specific neuronal ensemble firing patterns.

Dystonia, the third most common movement disorder, is characterized by involuntary muscle contractions that cause twisting movements and postures. Epidemiologic studies demonstrate that many dystonias are more common in women than men yet the mechanisms underlying these sex differences are largely unexplored. Basal ganglia dysfunction is consistently implicated across many forms of dystonia. The major input structure of the basal ganglia is the striatum where estrogen exerts neuromodulatory effects. In fact, the physiological properties of striatal spiny projection neurons (SPNs) are known to vary depending on biological sex and estrous cycle phase. Direct pathway SPNs (dSPNs) project to the internal globus pallidus to promote movement. Indirect pathway SPNs (iSPNs) project to the external globus pallidus to inhibit movement. Although dSPNs and iSPNs are segregated into separate pathways, they act in concert to mediate and refine movements. In dystonia patients, this coordinated activity is disrupted as functional imaging studies and microelectrode recordings suggest that both dSPNs and iSPNs are dysfunctional. However, the mechanisms underlying both SPN pathophysiology and sex differences in dystonia remain unknown. Several challenges have stymied our ability to understand the pathophysiology and the relationship to biological sex in dystonia. First, information obtained by studying patients is, by necessity, quite limited. Second, despite the epidemiological studies demonstrating sex differences in the expression of dystonia, sex as a biological variable is rarely incorporated into studies examining mechanisms underlying dystonia in patients or animal models. Third, we lack foundational studies in healthy controls that disentangle the effects of biological sex on striatal cell types. Indeed, studies characterizing sex differences in normal striatal physiology have not distinguished between SPN subtypes, while studies examining the molecular properties of dSPNs and iSPNs have not examined sex as a biological variable. This proposal addresses these gaps in knowledge. Our understanding of the pathophysiology of dystonia has also been hampered by the lack of animal models with sexually dimorphic dystonia caused by striatal dysfunction. To address this gap, we created a knockin mouse model of DOPA-responsive dystonia (DRD). In patients, DRD is female predominant, like many forms of dystonia in humans. DRD is also the prototype disorder for understanding basal ganglia dysfunction in dystonia In DRD mice, the striatum plays a central role in mediating dystonia, dSPN and iSPN signaling is disrupted and the dystonia is mediated by the estrous cycle. Thus, for the first time, it is possible to elucidate the neural code of dystonia in the context of the mechanisms that drive the sex differences. The Specific Aims are: 1. to determine the role of ovarian hormones in the expression of dystonia. 2. to identify sex differences in the molecular signature of dystonia in dSPNs and iSPNs. 3. to define sex differences in the pattern of dSPN and iSPN activity underlying dystonia.