-
CNS Neuroscience & Therapeutics Mar 2024The open-loop nature of conventional deep brain stimulation (DBS) produces continuous and excessive stimulation to patients which contributes largely to increased...
Real-time field-programmable gate array-based closed-loop deep brain stimulation platform targeting cerebellar circuitry rescues motor deficits in a mouse model of cerebellar ataxia.
AIMS
The open-loop nature of conventional deep brain stimulation (DBS) produces continuous and excessive stimulation to patients which contributes largely to increased prevalence of adverse side effects. Cerebellar ataxia is characterized by abnormal Purkinje cells (PCs) dendritic arborization, loss of PCs and motor coordination, and muscle weakness with no effective treatment. We aim to develop a real-time field-programmable gate array (FPGA) prototype targeting the deep cerebellar nuclei (DCN) to close the loop for ataxia using conditional double knockout mice with deletion of PC-specific LIM homeobox (Lhx)1 and Lhx5, resulting in abnormal dendritic arborization and motor deficits.
METHODS
We implanted multielectrode array in the DCN and muscles of ataxia mice. The beneficial effect of open-loop DCN-DBS or closed-loop DCN-DBS was compared by motor behavioral assessments, electromyography (EMG), and neural activities (neurospike and electroencephalogram) in freely moving mice. FPGA board, which performed complex real-time computation, was used for closed-loop DCN-DBS system.
RESULTS
Closed-loop DCN-DBS was triggered only when symptomatic muscle EMG was detected in a real-time manner, which restored motor activities, electroencephalogram activities and neurospike properties completely in ataxia mice. Closed-loop DCN-DBS was more effective than an open-loop paradigm as it reduced the frequency of DBS.
CONCLUSION
Our real-time FPGA-based DCN-DBS system could be a potential clinical strategy for alleviating cerebellar ataxia and other movement disorders.
Topics: Humans; Mice; Animals; Cerebellar Ataxia; Deep Brain Stimulation; Cerebellum; Purkinje Cells; Movement Disorders; Cerebellar Nuclei
PubMed: 38488445
DOI: 10.1111/cns.14638 -
The Journal of Physiology Apr 2024Mapping neuronal activation using calcium imaging in vivo during behavioural tasks has advanced our understanding of nervous system function. In almost all of these...
Mapping neuronal activation using calcium imaging in vivo during behavioural tasks has advanced our understanding of nervous system function. In almost all of these studies, calcium imaging is used to infer spike probabilities because action potentials activate voltage-gated calcium channels and increase intracellular calcium levels. However, neurons not only fire action potentials, but also convey information via intrinsic dynamics such as by generating bistable membrane potential states. Although a number of tools for spike inference have been developed and are currently being used, no tool exists for converting calcium imaging signals to maps of cellular state in bistable neurons. Purkinje neurons in the larval zebrafish cerebellum exhibit membrane potential bistability, firing either tonically or in bursts. Several studies have implicated the role of a population code in cerebellar function, with bistability adding an extra layer of complexity to this code. In the present study, we develop a tool, CaMLSort, which uses convolutional recurrent neural networks to classify calcium imaging traces as arising from either tonic or bursting cells. We validate this classifier using a number of different methods and find that it performs well on simulated event rasters as well as real biological data that it had not previously seen. Moreover, we find that CaMLsort generalizes to other bistable neurons, such as dopaminergic neurons in the ventral tegmental area of mice. Thus, this tool offers a new way of analysing calcium imaging data from bistable neurons to understand how they participate in network computation and natural behaviours. KEY POINTS: Calcium imaging, compriising the gold standard of inferring neuronal activity, does not report cellular state in neurons that are bistable, such as Purkinje neurons in the cerebellum of larval zebrafish. We model the relationship between Purkinje neuron electrical activity and its corresponding calcium signal to compile a dataset of state-labelled simulated calcium signals. We apply machine-learning methods to this dataset to develop a tool that can classify the state of a Purkinje neuron using only its calcium signal, which works well on real data even though it was trained only on simulated data. CaMLsort (Calcium imaging and Machine Learning based tool to sort intracellular state) also generalizes well to bistable neurons in a different brain region (ventral tegmental area) in a different model organism (mouse). This tool can facilitate our understanding of how these neurons carry out their functions in a circuit.
Topics: Mice; Animals; Calcium; Zebrafish; Purkinje Cells; Membrane Potentials; Action Potentials; Calcium, Dietary
PubMed: 38482722
DOI: 10.1113/JP284373 -
Brain : a Journal of Neurology Mar 2024Full-length RIM1 and 2 are key components of the presynaptic active zone that ubiquitously control excitatory and inhibitory neurotransmitter release. Here, we report...
Full-length RIM1 and 2 are key components of the presynaptic active zone that ubiquitously control excitatory and inhibitory neurotransmitter release. Here, we report that the function of the small RIM isoform RIM4, consisting of a single C2 domain, is strikingly different from that of the long isoforms. RIM4 is dispensable for neurotransmitter release but plays a postsynaptic, cell-type specific role in cerebellar Purkinje cells that is essential for normal motor function. In the absence of RIM4, Purkinje cell intrinsic firing is reduced and caffeine-sensitive, and dendritic integration of climbing fibre input is disturbed. Mice lacking RIM4, but not mice lacking RIM1/2, selectively in Purkinje cells exhibit a severe, hours-long paroxysmal dystonia. These episodes can also be induced by caffeine, ethanol or stress and closely resemble the deficits seen with mutations of the PNKD (paroxysmal non-kinesigenic dystonia) gene. Our data reveal essential postsynaptic functions of RIM proteins and show non-overlapping specialized functions of a small isoform despite high homology to a single domain in the full-length proteins.
PubMed: 38478593
DOI: 10.1093/brain/awae081 -
Cells Feb 2024Fetal alcohol spectrum disorders (FASD) caused by developmental ethanol exposure lead to cerebellar impairments, including motor problems, decreased cerebellar weight,...
Fetal alcohol spectrum disorders (FASD) caused by developmental ethanol exposure lead to cerebellar impairments, including motor problems, decreased cerebellar weight, and cell death. Alterations in the sole output of the cerebellar cortex, Purkinje cells, and central nervous system immune cells, microglia, have been reported in animal models of FASD. To determine how developmental ethanol exposure affects adult cerebellar microglia and Purkinje cells, we used a human third-trimester binge exposure model in which mice received ethanol or saline from postnatal (P) days 4-9. In adolescence, cerebellar cranial windows were implanted and mice were aged to young adulthood for examination of microglia and Purkinje cells in vivo with two-photon imaging or in fixed tissue. Ethanol had no effect on microglia density, morphology, dynamics, or injury response. However, Purkinje cell linear frequency was reduced by ethanol. Microglia-Purkinje cell interactions in the Purkinje Cell Layer were altered in females compared to males. Overall, developmental ethanol exposure had few effects on cerebellar microglia in young adulthood and Purkinje cells appeared to be more susceptible to its effects.
Topics: Pregnancy; Male; Humans; Female; Animals; Mice; Young Adult; Adult; Aged; Ethanol; Purkinje Cells; Fetal Alcohol Spectrum Disorders; Microglia; Cerebellum; Disease Models, Animal
PubMed: 38474350
DOI: 10.3390/cells13050386 -
Cerebellum (London, England) Mar 2024Responding to burst stimulation of parallel fibers (PFs), cerebellar Purkinje neurons (PNs) generate a convolved synaptic response displaying a fast excitatory...
Responding to burst stimulation of parallel fibers (PFs), cerebellar Purkinje neurons (PNs) generate a convolved synaptic response displaying a fast excitatory postsynaptic current (EPSC) followed by a slow EPSC (EPSC). The latter is companied with a rise of intracellular Ca and critical for motor coordination. The genesis of EPSC in PNs results from activation of metabotropic type 1 glutamate receptor (mGluR1), oligomerization of stromal interaction molecule 1 (STIM1) on the membrane of endoplasmic reticulum (ER) and opening of transient receptor potential canonical 3 (TRPC3) channels on the plasma membrane. Neuronal nitric oxide synthase (nNOS) is abundantly expressed in PFs and granule neurons (GNs), catalyzing the production of nitric oxide (NO) hence regulating PF-PN synaptic function. We recently found that nNOS/NO regulates the morphological development of PNs through mGluR1-regulated Ca-dependent mechanism. This study investigated the role of nNOS/NO in regulating EPSC. Electrophysiological analyses showed that EPSC in cerebellar slices of nNOS knockout (nNOS) mice was significantly larger than that in wildtype (WT) mice. Activation of mGluR1 in cultured PNs from nNOS mice evoked larger TRPC3-channel mediated currents and intracellular Ca rise than that in PNs from WT mice. In addition, nNOS inhibitor and NO-donor increased and decreased, respectively, the TRPC3-current and Ca rise in PNs. Moreover, the NO-donor effectively decreased TRPC3 currents in HEK293 cells expressing WT STIM1, but not cells expressing a STIM1 with cysteine mutants. These novel findings indicate that nNOS/NO inhibits TRPC3-containig channel mediated cation influx during EPSC, at least in part, by S-nitrosylation of STIM1.
PubMed: 38472628
DOI: 10.1007/s12311-024-01683-0 -
Cerebellum (London, England) Mar 2024Climbing fibers, connecting the inferior olive and Purkinje cells, form the nervous system's strongest neural connection. These fibers activate after critical events...
Climbing fibers, connecting the inferior olive and Purkinje cells, form the nervous system's strongest neural connection. These fibers activate after critical events like motor errors or anticipation of rewards, leading to bursts of excitatory postsynaptic potentials (EPSPs) in Purkinje cells. The number of EPSPs is a crucial variable when the brain is learning a new motor skill. Yet, we do not know what determines the number of EPSPs. Here, we measured the effect of nucleo-olivary stimulation on periorbital elicited climbing fiber responses through in-vivo intracellular Purkinje cell recordings in decerebrated ferrets. The results show that while nucleo-olivary stimulation decreased the probability of a response occurring at all, it did not reduce the number of EPSPs. The results suggest that nucleo-olivary stimulation does not influence the number of EPSPs in climbing fiber bursts.
PubMed: 38467957
DOI: 10.1007/s12311-024-01682-1 -
Ecotoxicology and Environmental Safety Apr 2024Deltamethrin (DM) is a highly effective and widely used pyrethroid pesticide. It is an environmental factor affecting public and occupational health and exerts direct...
Deltamethrin (DM) is a highly effective and widely used pyrethroid pesticide. It is an environmental factor affecting public and occupational health and exerts direct toxic effects on the central nervous system. As the major target organs for neurotoxicity of DM, the hippocampus and the cerebellum are critical to the learning and motor function. Pregnant Wistar rats were randomly divided into four groups and gavaged at doses of 0, 1, 4or 10 mg/kg/d DM from gestational day (GD) 0 to postnatal day (PN) 21. The PC12 cells were selected to further verify the regulatory mechanisms of DM on the neurodevelopmental injury. We found that maternal exposure to DM caused learning, memory and motor dysfunction in male offspring. Maternal exposure to DM induced the decrease in the density of hippocampal dendritic spines in male offspring through the reduced expression of M1 mAchRs, which in turn reduced the mediated AKT/mTOR signaling pathway, contributing to the inhibition of dynamic changes of GluA1. Meanwhile, DM exposure inhibited the BDNF/TrkB signaling pathway, thereby reducing phosphorylation of stathmin and impairing cerebellar purkinje cell dendrite growth and development. Taken together, maternal exposure to DM during pregnancy and lactation could impair neurodevelopment of male offspring.
Topics: Pregnancy; Rats; Animals; Humans; Female; Male; Maternal Exposure; Rats, Wistar; Prenatal Exposure Delayed Effects; Lactation; Hippocampus; Nitriles; Pyrethrins
PubMed: 38461575
DOI: 10.1016/j.ecoenv.2024.116196 -
Development (Cambridge, England) Apr 2024Cerebellar neurons, such as GABAergic Purkinje cells (PCs), interneurons (INs) and glutamatergic granule cells (GCs) are differentiated from neural progenitors...
Cerebellar neurons, such as GABAergic Purkinje cells (PCs), interneurons (INs) and glutamatergic granule cells (GCs) are differentiated from neural progenitors expressing proneural genes, including ptf1a, neurog1 and atoh1a/b/c. Studies in mammals previously suggested that these genes determine cerebellar neuron cell fate. However, our studies on ptf1a;neurog1 zebrafish mutants and lineage tracing of ptf1a-expressing progenitors have revealed that the ptf1a/neurog1-expressing progenitors can generate diverse cerebellar neurons, including PCs, INs and a subset of GCs in zebrafish. The precise mechanisms of how each cerebellar neuron type is specified remains elusive. We found that genes encoding the transcriptional regulators Foxp1b, Foxp4, Skor1b and Skor2, which are reportedly expressed in PCs, were absent in ptf1a;neurog1 mutants. foxp1b;foxp4 mutants showed a strong reduction in PCs, whereas skor1b;skor2 mutants completely lacked PCs, and displayed an increase in immature GCs. Misexpression of skor2 in GC progenitors expressing atoh1c suppressed GC fate. These data indicate that Foxp1b/4 and Skor1b/2 function as key transcriptional regulators in the initial step of PC differentiation from ptf1a/neurog1-expressing neural progenitors, and that Skor1b and Skor2 control PC differentiation by suppressing their differentiation into GCs.
Topics: Animals; Cell Differentiation; Cerebellum; Co-Repressor Proteins; Forkhead Transcription Factors; Mammals; Neurons; Purkinje Cells; Zebrafish; Zebrafish Proteins
PubMed: 38456494
DOI: 10.1242/dev.202546 -
ELife Mar 2024Determining the sites and directions of plasticity underlying changes in neural activity and behavior is critical for understanding mechanisms of learning. Identifying...
Determining the sites and directions of plasticity underlying changes in neural activity and behavior is critical for understanding mechanisms of learning. Identifying such plasticity from neural recording data can be challenging due to feedback pathways that impede reasoning about cause and effect. We studied interactions between feedback, neural activity, and plasticity in the context of a closed-loop motor learning task for which there is disagreement about the loci and directions of plasticity: vestibulo-ocular reflex learning. We constructed a set of circuit models that differed in the strength of their recurrent feedback, from no feedback to very strong feedback. Despite these differences, each model successfully fit a large set of neural and behavioral data. However, the patterns of plasticity predicted by the models fundamentally differed, with the direction of plasticity at a key site changing from depression to potentiation as feedback strength increased. Guided by our analysis, we suggest how such models can be experimentally disambiguated. Our results address a long-standing debate regarding cerebellum-dependent motor learning, suggesting a reconciliation in which learning-related changes in the strength of synaptic inputs to Purkinje cells are compatible with seemingly oppositely directed changes in Purkinje cell spiking activity. More broadly, these results demonstrate how changes in neural activity over learning can appear to contradict the sign of the underlying plasticity when either internal feedback or feedback through the environment is present.
Topics: Cerebellum; Purkinje Cells; Learning; Reflex, Vestibulo-Ocular; Feedback; Neuronal Plasticity
PubMed: 38451856
DOI: 10.7554/eLife.84770