Biology subjects

Sillitoe, R. V.

Publications and source records attributed to Sillitoe, R. V..

At least 19 recordsLinked to original sources

bioRxiv2026

Age-Adjusted Cerebellar Volumetry and Developmental Outcomes in Extremely Low Birth Weight Infants

Background: Infants with extremely low birth weight (ELBW) are at high risk for neurodevelopmental impairment, but the relationship between cerebellar structure and later developmental outcome remains incompletely defined. Methods: In this retrospective single-center study, we examined total cerebellar volume on clinically acquired brain magnetic resonance imaging (MRI) in ELBW infants while accounting for postmenstrual age (PMA) at imaging. Results: Of 65 infants screened, 42 were included. Mean gestational age at birth was 25.54 {+/-} 1.68 weeks, mean birth weight was 733.2 {+/-} 118.7 g, and mean PMA at MRI was 43.02 {+/-} 6.53 weeks (range, 31.57--68.00). Mean cerebellar volume was 22.17 {+/-} 9.63 cm. Independently adjudicated developmental outcomes comprised normal development in 16 infants, isolated or specific impairment in 12, and moderate/severe impairment in 14. Unadjusted cerebellar volumes did not differ across developmental groups (P = 0.490) or qualitative MRI categories (P = 0.875). However, the PMA-by-developmental-category interaction was significant (P = 0.002), with estimated cross-sectional slopes of 1.72, 1.56, and 0.39 cm per week, respectively. The interaction remained significant within 36--46 weeks PMA (n = 29; P = 0.011) and after adjustment for small-for-gestational-age (SGA) status. Sensitivity analyses indicated uncertainty in the stability of the interaction. Conclusions: These findings suggest that age-informed cerebellar volumetric patterns may provide developmental information not evident from average volumes alone and support prospective validation with standardized imaging and developmental assessments. As a result, cerebellar volumes obtained early in life may hold prognostic information for ELBW infants.

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bioRxiv2026

Human and mouse cerebellar inhibitory circuits in dystonic crisis and their modulation with therapeutic stimulation

Dystonia is a neurological movement disorder characterized by abnormal muscle contractions that, at their most severe, lead to a life-threatening condition - dystonic crisis. Yet, therapeutic options remain limited by our incomplete understanding of what neural circuits underly the condition. Although cerebellar nuclei neurons are implicated in the origin of baseline dystonic symptoms, it is unclear whether their activity drives dystonic crisis. To explore this role, we found that cerebellar abnormalities and neural inhibition were recurring targets in patients with dystonic crisis, implicating cerebellar inhibitory neurons in its development. We devised a mouse genetics approach to test whether inhibitory cerebellar nuclei neurons (iCNNs) induce dystonic crisis. Directional optogenetic modulation of iCNNs induced dystonic crises on-demand and alleviated spontaneous crises in mice that mimic spontaneous dystonic crises. To investigate whether iCNNs interact with other motor areas during dystonic crisis, we identified monosynaptic iCNN projections to the centrolateral nucleus of the thalamus (CL). Deep brain stimulation of the CL alleviated dystonic crises induced by iCNN photoactivation. Our data uncover a cell type-specific cerebellar origin of dystonic crisis and highlight its therapeutic potential.

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bioRxiv2026

Frequency-dependent cerebellar circuits independently gate social vocalizations and movement

Communication depends on precise coordination between motor execution and cognition. Here we reveal that the cerebellum exerts real-time control over social vocalizations in adult mice. Optogenetic activation of excitatory cerebellar output in the superior cerebellar peduncle suppressed ultrasonic vocalizations with frequency-dependent potency while inducing distinct motor phenotypes. Systematic, functional mapping across cerebellar regions and cell types revealed that vocal suppression can occur in the absence of overt motor impairment, suggesting selective control of vocal output beyond gross movement disruption. We identified the periaqueductal gray (PAG), a conserved midbrain vocal control center, as a key downstream mediator of this effect. Deep brain stimulation of the PAG rescued vocal deficits in a model of cerebellar dysfunction without rescuing motor incoordination. These findings define a cerebellar-midbrain pathway that gates vocal behavior and demonstrate that targeted therapeutic neuromodulation can selectively restore communication-related output even in the presence of persistent cerebellar-driven motor deficits.

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bioRxiv2025

Cerebellar Purkinje cell stripe patterns reveal a differential vulnerability and resistance to cell loss during normal aging in mice

Age-related neurodegenerative diseases involve reduced cell numbers and impaired behavioral capacity. Neurodegeneration and behavioral deficits also occur during aging, and notably in the absence of disease. The cerebellum, which modulates movement and cognition, is susceptible to cell loss in both aging and disease. Here, we demonstrate that cerebellar Purkinje cell loss in aged mice is not spatially random but rather occurs in a pattern of parasagittal stripes. We also find that aged mice exhibit impaired motor coordination and more severe tremor compared to younger mice. However, the relationship between patterned Purkinje cell loss and motor dysfunction is not straightforward. Examination of postmortem samples of human cerebella from neurologically typical individuals supports the presence of selective loss of Purkinje cells during aging. These data reveal a spatiotemporal cellular substrate for aging in the cerebellum that may inform how neuronal vulnerability leads to neurodegeneration and the ensuing deterioration of behavior.

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bioRxiv2024

Developmental transformations of Purkinje cells tracked by DNA electrokinetic mobility

Brain development relies on orchestrated placement and timing of neurogenesis in progenitor zones to produce the expansive cellular diversity of the brain. We took advantage of bioelectric interactions between DNA and embryonic tissue to perform "stereo-tracking", a developmental targeting strategy that differentially labels cells positioned at different depths within intact progenitor zones. This three-dimensional labeling was achieved by delivery of plasmids with distinct electrokinetic mobilities into neural progenitor zones in utero. We applied stereo-tracking with light sheet imaging in the cerebellum and identified that Purkinje cells follow embryonically committed developmental trajectories linking distinct progenitor zone fields to the topography of the mature cerebellar cortex. In the process of stereo-tracking, we identified a previously unreported subcellular structure on the axon initial segment of Purkinje cells. These structures, we termed "axon bubbles", are developmentally timed and differentially labeled by lipid-modified proteins. Our findings demonstrate key rules that orchestrate the stereotyped transformations from fetal progenitors into mature networks of neuronal circuits, and demonstrate the potential of progenitor zone stereo-tracking to reveal new biology within intact developing systems.

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bioRxiv2024

Targeting DBS to the centrolateral thalamic nucleus improves movement in a lesion-based model of acquired cerebellar dystonia in mice

Dystonia is the third most common movement disorder and an incapacitating co-morbidity in a variety of neurologic conditions. Dystonia can be caused by genetic, degenerative, idiopathic, and acquired etiologies, which are hypothesized to converge on a "dystonia network" consisting of the basal ganglia, thalamus, cerebellum, and cerebral cortex. In acquired dystonia, focal lesions to subcortical areas in the network - the basal ganglia, thalamus, and cerebellum - lead to a dystonia that can be difficult to manage with canonical treatments, including deep brain stimulation (DBS). While studies in animal models have begun to parse the contribution of individual nodes in the dystonia network, how acquired injury to the cerebellar outflow tracts instigates dystonia; and how network modulation interacts with symptom latency remain as unexplored questions. Here, we present an electrolytic lesioning paradigm that bilaterally targets the cerebellar outflow tracts. We found that lesioning these tracts, at the junction of the superior cerebellar peduncles and the medial and intermediate cerebellar nuclei, resulted in acute, severe dystonia. We observed that dystonia is reduced with one hour of DBS of the centrolateral thalamic nucleus, a first order node in the network downstream of the cerebellar nuclei. In contrast, one hour of stimulation at a second order node in the short latency, disynaptic projection from the cerebellar nuclei, the striatum, did not modulate the dystonia in the short-term. Our study introduces a robust paradigm for inducing acute, severe dystonia, and demonstrates that targeted modulation based on network principles powerfully rescues motor behavior. These data inspire the identification of therapeutic targets for difficult to manage acquired dystonia.

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bioRxiv2023

Cerebellar deep brain stimulation as a dual function therapeutic for restoring movement and sleep in dystonic mice

Dystonia arises with cerebellar dysfunction, which plays a key role in the emergence of multiple pathophysiological deficits that range from abnormal movements and postures to disrupted sleep. Current therapeutic interventions typically do not simultaneously address both the motor and non-motor (sleep-related) symptoms of dystonia, underscoring the necessity for a multi-functional therapeutic strategy. Deep brain stimulation (DBS) is effectively used to reduce motor symptoms in dystonia, with existing parallel evidence arguing for its potential to correct sleep disturbances. However, the simultaneous efficacy of DBS for improving sleep and motor dysfunction, specifically by targeting the cerebellum, remains underexplored. Here, we test the effect of cerebellar DBS in two genetic mouse models with dystonia that exhibit sleep defects-- Ptf1aCre;Vglut2fx/fxand Pdx1Cre;Vglut2fx/fx--which have overlapping cerebellar circuit miswiring defects but differing severity in motor phenotypes. By targeting DBS to the cerebellar fastigial and interposed nuclei, we modulated sleep dysfunction by enhancing sleep quality and timing in both models. This DBS paradigm improved wakefulness (decreased) and rapid eye movement (REM) sleep (increased) in both mutants. Additionally, the latency to reach REM sleep, a deficit observed in human dystonia patients, was reduced in both models. Cerebellar DBS also induced alterations in the electrocorticogram (ECoG) patterns that define sleep states. As expected, DBS reduced the severe dystonic twisting motor symptoms that are observed in the Ptf1aCre;Vglut2fx/fx mutant mice. These findings highlight the potential for using cerebellar DBS to improve sleep and reduce motor dysfunction in dystonia and uncover its potential as a dual-effect in vivo therapeutic strategy.

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bioRxiv2023

Purkinje cell dysfunction causes disrupted sleep in ataxic mice

Purkinje cell dysfunction causes movement disorders such as ataxia, however, recent evidence suggests that Purkinje cell dysfunction may also alter sleep regulation. Here, we used an ataxia mouse model generated by silencing Purkinje cell neurotransmission (L7Cre;Vgatfx/fx) to better understand how cerebellar dysfunction impacts sleep physiology. We focused our analysis on sleep architecture and electrocorticography (ECoG) patterns based on their relevance to extracting physiological measurements during sleep. We found that circadian activity is unaltered in the mutant mice, although their sleep parameters and ECoG patterns are modified. The L7Cre;Vgatfx/fx mutant mice have decreased wakefulness and rapid eye movement (REM) sleep, while non-rapid eye movement (NREM) sleep is increased. The mutant mice have an extended latency to REM sleep, which is also observed in human ataxia patients. Spectral analysis of ECoG signals revealed alterations in the power distribution across different frequency bands defining sleep. Therefore, Purkinje cell dysfunction may influence wakefulness and equilibrium of distinct sleep stages in ataxia. Our findings posit a connection between cerebellar dysfunction and disrupted sleep and underscore the importance of examining cerebellar circuit function in sleep disorders. Summary StatementUtilizing a precise genetic mouse model of ataxia, we provide insights into the cerebellums role in sleep regulation, highlighting its potential as a therapeutic target for motor disorders-related sleep disruptions.

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bioRxiv2023

Neural spike signatures determine the behavioral presentation of cerebellar disease

The cerebellum contributes to a diverse array of motor conditions including ataxia, dystonia, and tremor. The neural substrates that encode this diversity are unclear. Here, we tested whether the neural spike activity of cerebellar output neurons is distinct between movement disorders with different impairments, generalizable across movement disorders with similar impairments, and capable of causing distinct movement impairments. Using in vivo awake recordings as input data, we trained a supervised classifier model to differentiate the spike parameters between mouse models for ataxia, dystonia, and tremor. The classifier model correctly assigned mouse phenotypes based on single neuron signatures. Spike signatures were shared across etiologically distinct but phenotypically similar disease models. Mimicking these pathophysiological spike signatures with optogenetics induced the predicted motor impairments in otherwise healthy mice. These data show that distinct spike signatures promote the behavioral presentation of cerebellar diseases.

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bioRxiv2023

Disrupted sleep in dystonia depends on cerebellar function but not motor symptoms in mice

Although dystonia is the third most common movement disorder, patients often also experience debilitating nonmotor defects including impaired sleep. The cerebellum is a central component of a "dystonia network" that plays various roles in sleep regulation. Importantly, the primary driver of sleep impairments in dystonia remains poorly understood. The cerebellum, along with other nodes in the motor circuit, could disrupt sleep. However, it is unclear how the cerebellum might alter sleep and mobility. To disentangle the impact of cerebellar dysfunction on motion and sleep, we generated two mouse genetic models of dystonia that have overlapping cerebellar circuit miswiring but show differing motor phenotype severity: Ptf1aCre;Vglut2fx/fx and Pdx1Cre;Vglut2fx/fx mice. In both models, excitatory climbing fiber to Purkinje cell neurotransmission is blocked, but only the Ptf1aCre;Vglut2fx/fx mice have severe twisting. Using in vivo ECoG and EMG recordings we found that both mutants spend greater time awake and in NREM sleep at the expense of REM sleep. The increase in awake time is driven by longer awake bouts rather than an increase in bout number. We also found a longer latency to reach REM in both mutants, which is similar to what is reported in human dystonia. We uncovered independent but parallel roles for cerebellar circuit dysfunction and motor defects in promoting sleep quality versus posture impairments in dystonia.

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bioRxiv2022

Influence of data sampling methods on the representation of neural spiking activity in vivo

In vivo single-unit recordings distinguish the basal spiking properties of neurons in different experimental settings and disease states. Here, we examined over 300 spike trains recorded from Purkinje cells and cerebellar nuclei neurons to test whether data sampling approaches influence the extraction of rich descriptors of firing properties. Our analyses included neurons recorded in awake and anesthetized control mice, as well as disease models of ataxia, dystonia, and tremor. We find that recording duration circumscribes overall representations of firing rate and pattern. Notably, shorter recording durations skew estimates for global firing rate variability towards lower values. We also find that only some populations of neurons in the same mouse are more similar to each other than to neurons recorded in different mice. These data reveal that recording duration and approach are primary considerations when interpreting task-independent single-neuron firing properties. If not accounted for, group differences may be concealed or exaggerated.

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bioRxiv2021

The cerebellum initiates severe tonic-clonic seizures by altering neuronal activity in the ventral posteromedial nucleus (VPM) of the thalamus

Thalamo-cortical networks are central to seizures, yet its unclear how these circuits initiate the seizures. Here, we test the hypothesis that a facial region of the thalamus, the VPM, is a source of convulsive, tonic-clonic seizures. We devised an in vivo optogenetic mouse model to elicit tonic-clonic seizures by driving convergent input to the VPM. With viral tracing, we show dense cerebellar and cerebral cortical afferent input to the VPM. Lidocaine microinfusions into the cerebellar nuclei selectively block seizure initiation. We perform single-unit electrophysiology recordings during awake, convulsive seizures to define the local activity of thalamic neurons before, during, and after seizure onset. We find highly dynamic activity with biphasic properties, raising the possibility that heterogenous activity patterns promote seizures. These data reveal the VPM as a source of tonic-clonic seizures, with cerebellar input providing the predominant signals.

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bioRxiv2020

Deleting Mecp2 from the entire cerebellum rather than its neuronal subtypes causes a delay in motor learning in mice

Rett syndrome is a devastating childhood neurological disorder caused by mutations in MECP2. Of the many symptoms, motor deterioration is a significant problem for patients. In mice, deleting Mecp2 from the cortex or basal ganglia causes motor dysfunction, hypoactivity, and tremor, which are abnormalities observed in patients. However, little is known about the consequences of deleting Mecp2 from the cerebellum, a brain region critical for motor function. Here we show that deleting Mecp2 from the entire cerebellum, but not from individual cerebellar cell types, causes a delay in motor learning that is overcome by additional training. We also observed irregular firing rates of Purkinje cells and transcriptional misregulation within the cerebellum of knockout mice. These findings demonstrate that the motor deficits present in Rett syndrome arise, in part, from cerebellar dysfunction. For Rett syndrome as well as other neurodevelopmental disorders, our results highlight the importance of understanding which brain regions contribute to disease phenotypes.

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bioRxiv2020

Maturation of Purkinje cell firing properties relies on granule cell neurogenesis

Preterm infants that suffer cerebellar insults often develop motor disorders and cognitive difficulty. Granule cells are especially vulnerable, and they likely instigate disease by impairing the function of Purkinje cells. Here, we use regional genetic manipulations and in vivo electrophysiology to test whether granule cells help establish the firing properties of Purkinje cells during postnatal mouse development. We generated mice that lack granule cell neurogenesis and tracked the structural and functional consequences on Purkinje cells in these agranular pups. We reveal that Purkinje cells fail to acquire their typical connectivity and morphology, and the formation of characteristic Purkinje cell firing patterns is delayed by one week. We also show that the agranular pups have impaired motor behaviors and vocal skills. These data argue that granule cell neurogenesis sets the maturation time window for Purkinje cell function and refines cerebellar-dependent behaviors.

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bioRxiv2020

Cerebellar modulation of gamma coherence between prefrontal cortex and hippocampus during spatial working memory decision making

Spatial working memory (SWM) is a cognitive skill supporting survival-relevant behaviors, such as optimizing foraging behavior by remembering recent routes and visited sites. It is known that SWM decision-making in rodents requires the medial prefrontal cortex (mPFC) and dorsal hippocampus. The decision process in SWM tasks carries a specific electrophysiological signature of a brief, decision-related increase in neuronal communication in the form of an increase in the coherence of neuronal theta oscillations (4-12 Hz) between the mPFC and dorsal hippocampus, a finding we replicated here during spontaneous exploration of a plus maze in freely moving mice. We further evaluated SWM decision-related coherence changes within frequency bands above theta. Decision-related coherence increases occurred in seven frequency bands between 4 and 200 Hz and decision-outcome related differences in coherence modulation occurred within the beta and gamma frequency bands and in higher frequency oscillations up to 130 Hz. With recent evidence that Purkinje cells in the cerebellar lobulus simplex (LS) represent information about the phase and phase differences of gamma oscillations in the mPFC and dorsal hippocampus, we hypothesized that LS might be involved in the modulation of mPFC-hippocampal gamma coherence. We show that optical stimulation of LS significantly impairs SWM performance and decision-related mPFC-dCA1 coherence modulation, providing causal evidence for an involvement of cerebellar LS in SWM decision making at the behavioral and neuronal level. Our findings suggest that the cerebellum might contribute to SWM decision-making by optimizing the decision-related modulation of mPFC-dCA1 coherence.

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bioRxiv2020

Purkinje cell neurotransmission patterns cerebellar basket cells into zonal modules that are defined by distinct pinceau sizes

Ramon y Cajal proclaimed the neuron doctrine based on circuit features he exemplified using cerebellar basket cell projections. Basket cells form dense inhibitory plexuses that wrap Purkinje cell somata and terminate as pinceaux at the initial segment of axons. Here, we demonstrate that HCN1, Kv1.1, PSD95 and GAD67 unexpectedly mark patterns of basket cell pinceaux that map onto Purkinje cell functional zones. Using cell-specific genetic tracing with an Ascl1CreERT2 mouse conditional allele, we reveal that basket cell zones comprise different sizes of pinceaux. We tested whether Purkinje cells instruct the assembly of inhibitory projections into zones, as they do for excitatory afferents. Genetically silencing Purkinje cell neurotransmission blocks the formation of sharp Purkinje cell zones and disrupts excitatory axon patterning. The distribution of pinceaux into size-specific zones is eliminated without Purkinje cell output. Our data uncover the cellular and molecular diversity of a foundational synapse that revolutionized neuroscience.

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bioRxiv2019

Cerebellar Purkinje cell microcircuits are essential for tremor

Tremor is currently ranked as the most common movement disorder. The brain regions and neural signals that initiate the debilitating shakiness of different body parts remain unclear. Here, we found that genetically silencing cerebellar Purkinje cell activity blocked tremor in mice that were given the tremorgenic drug harmaline. We show in awake behaving mice that the onset of tremor is coincident with rhythmic Purkinje cell firing, which alters the output of their target cerebellar nuclei cells. We mimic the tremorgenic action of the drug with optogenetics and present evidence that highly patterned Purkinje cell activity drives a powerful tremor in otherwise normal mice. Modulating the altered activity with deep brain stimulation directed to the Purkinje cell output in the cerebellar nuclei reduced tremor in freely moving mice. Together, the data implicate Purkinje cell connectivity as a neural substrate for tremor and a gateway for signals that mediate the disease.

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bioRxiv2018

Molecular layer interneurons shape the spike activity of cerebellar Purkinje cells

One-sentence summaryCerebellar stellate cells and basket cells shape distinct Purkinje cell firing properties\n\nAbstractPurkinje cells receive synaptic input from several classes of interneurons. Here, we address the roles of inhibitory molecular layer interneurons in establishing Purkinje cell function in vivo. Using conditional genetics approaches in mice, we compare how the lack of stellate cell versus basket cell GABAergic neurotransmission sculpts the firing properties of Purkinje cells. We take advantage of an inducible Ascl1CreER allele to spatially and temporally target the deletion of the vesicular GABA transporter, Vgat, in developing neurons. Selective depletion of basket cell GABAergic neurotransmission increases the frequency of Purkinje cell simple spike firing and decreases the frequency of complex spike firing in adult behaving mice. In contrast, lack of stellate cell communication increases the regularity of Purkinje cell simple spike firing while increasing the frequency of complex spike firing. Our data uncover complementary roles for molecular layer interneurons in shaping the rate and pattern of Purkinje cell activity in vivo.

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