Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 137
Filtrar
1.
Rinsho Shinkeigaku ; 2024 May 30.
Artigo em Japonês | MEDLINE | ID: mdl-38811203

RESUMO

Malfunction of the basal ganglia leads to movement disorders such as Parkinson's disease, dystonia, Huntington's disease, dyskinesia, and hemiballism, but their underlying pathophysiology is still subject to debate. To understand their pathophysiology in a unified manner, we propose the "dynamic activity model", on the basis of alterations of cortically induced responses in individual nuclei of the basal ganglia. In the normal state, electric stimulation in the motor cortex, mimicking cortical activity during initiation of voluntary movements, evokes a triphasic response consisting of early excitation, inhibition, and late excitation in the output stations of the basal ganglia of monkeys, rodents, and humans. Among three components, cortically induced inhibition, which is mediated by the direct pathway, releases an appropriate movement at an appropriate time by disinhibiting thalamic and cortical activity, whereas early and late excitation, which is mediated by the hyperdirect and indirect pathways, resets on-going cortical activity and stops movements, respectively. Cortically induced triphasic response patterns are systematically altered in various movement disorder models and could well explain the pathophysiology of their motor symptoms. In monkey and mouse models of Parkinson's disease, cortically induced inhibition is reduced and prevents the release of movements, resulting in akinesia/bradykinesia. On the other hand, in a mouse model of dystonia, cortically induced inhibition is enhanced and releases unintended movements, inducing involuntary muscle contractions. Moreover, after blocking the subthalamic nucleus activity in a monkey model of Parkinson's disease, cortically induced inhibition is recovered and enables voluntary movements, explaining the underlying mechanism of stereotactic surgery to ameliorate parkinsonian motor signs. The "dynamic activity model" gives us a more comprehensive view of the pathophysiology underlying motor symptoms of movement disorders and clues for their novel therapies.

2.
J Neurosci ; 44(12)2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38290848

RESUMO

The subthalamic nucleus (STN) receives cortical inputs via the hyperdirect and indirect pathways, projects to the output nuclei of the basal ganglia, and plays a critical role in the control of voluntary movements and movement disorders. STN neurons change their activity during execution of movements, while recent studies emphasize STN activity specific to cancelation of movements. To address the relationship between execution and cancelation functions, we examined STN activity in two Japanese monkeys (Macaca fuscata, both sexes) who performed a goal-directed reaching task with a delay that included Go, Cancel, and NoGo trials. We first examined responses to the stimulation of the forelimb regions in the primary motor cortex and/or supplementary motor area. STN neurons with motor cortical inputs were found in the dorsal somatomotor region of the STN. All these STN neurons showed activity changes in Go trials, suggesting their involvement in execution of movements. Part of them exhibited activity changes in Cancel trials and sustained activity during delay periods, suggesting their involvement in cancelation of planed movements and preparation of movements, respectively. The STN neurons rarely showed activity changes in NoGo trials. Go- and Cancel-related activity was selective to the direction of movements, and the selectivity was higher in Cancel trials than in Go trials. Changes in Go- and Cancel-related activity occurred early enough to initiate and cancel movements, respectively. These results suggest that the dorsal somatomotor region of the STN, which receives motor cortical inputs, is involved in preparation and execution of movements and cancelation of planned movements.


Assuntos
Córtex Motor , Núcleo Subtalâmico , Masculino , Feminino , Animais , Haplorrinos , Núcleo Subtalâmico/fisiologia , Gânglios da Base , Córtex Motor/fisiologia , Neurônios/fisiologia
3.
Neurobiol Dis ; 190: 106362, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37992783

RESUMO

The external segment of the globus pallidus (GPe) has long been considered a homogeneous structure that receives inputs from the striatum and sends processed information to the subthalamic nucleus, composing a relay nucleus of the indirect pathway that contributes to movement suppression. Recent methodological revolution in rodents led to the identification of two distinct cell types in the GPe with different fiber connections. The GPe may be regarded as a dynamic, complex and influential center within the basal ganglia circuitry, rather than a simple relay nucleus. On the other hand, many studies have so far been performed in monkeys to clarify the functions of the basal ganglia in the healthy and diseased states, but have not paid much attention to such classification and functional differences of GPe neurons. In this minireview, we consider the knowledge on the rodent GPe and discuss its impact on the understanding of the basal ganglia circuitry in monkeys.


Assuntos
Globo Pálido , Núcleo Subtalâmico , Globo Pálido/metabolismo , Corpo Estriado , Gânglios da Base/fisiologia , Neurônios/metabolismo , Vias Neurais/fisiologia
4.
Mov Disord ; 38(12): 2145-2150, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37986211

RESUMO

Schematic illustration of cortically induced dynamic activity changes of the output nuclei of the basal ganglia (the internal segment of the globus pallidus, GPi and the substantia nigra pars reticulata, SNr) in the healthy and diseased states. The height of the dam along the time course controls the expression of voluntary movements. Its alterations could cause a variety of movement disorders, such as Parkinson's disease and hyperkinetic disorders. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.


Assuntos
Transtornos dos Movimentos , Doença de Parkinson , Humanos , Gânglios da Base , Globo Pálido , Substância Negra
5.
Cell Rep Med ; 4(10): 101208, 2023 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-37774703

RESUMO

Dyskinesia is involuntary movement caused by long-term medication with dopamine-related agents: the dopamine agonist 3,4-dihydroxy-L-phenylalanine (L-DOPA) to treat Parkinson's disease (L-DOPA-induced dyskinesia [LID]) or dopamine antagonists to treat schizophrenia (tardive dyskinesia [TD]). However, it remains unknown why distinct types of medications for distinct neuropsychiatric disorders induce similar involuntary movements. Here, we search for a shared structural footprint using magnetic resonance imaging-based macroscopic screening and super-resolution microscopy-based microscopic identification. We identify the enlarged axon terminals of striatal medium spiny neurons in LID and TD model mice. Striatal overexpression of the vesicular gamma-aminobutyric acid transporter (VGAT) is necessary and sufficient for modeling these structural changes; VGAT levels gate the functional and behavioral alterations in dyskinesia models. Our findings indicate that lowered type 2 dopamine receptor signaling with repetitive dopamine fluctuations is a common cause of VGAT overexpression and late-onset dyskinesia formation and that reducing dopamine fluctuation rescues dyskinesia pathology via VGAT downregulation.


Assuntos
Discinesia Induzida por Medicamentos , Transtornos Parkinsonianos , Camundongos , Animais , Agonistas de Dopamina/efeitos adversos , Levodopa/efeitos adversos , Dopamina , Antiparkinsonianos/efeitos adversos , Transtornos Parkinsonianos/induzido quimicamente , Transtornos Parkinsonianos/patologia , Discinesia Induzida por Medicamentos/etiologia , Discinesia Induzida por Medicamentos/tratamento farmacológico , Discinesia Induzida por Medicamentos/patologia , Oxidopamina/efeitos adversos , Ácido gama-Aminobutírico/efeitos adversos
6.
Commun Biol ; 6(1): 914, 2023 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-37673949

RESUMO

Neurons comprising nigrostriatal system play important roles in action selection. However, it remains unclear how this system integrates recent outcome information with current action (movement) and outcome (reward or no reward) information to achieve appropriate subsequent action. We examined how neuronal activity of substantia nigra pars compacta (SNc) and dorsal striatum reflects the level of reward expectation from recent outcomes in rats performing a reward-based choice task. Movement-related activity of direct and indirect pathway striatal projection neurons (dSPNs and iSPNs, respectively) were enhanced by reward expectation, similarly to the SNc dopaminergic neurons, in both medial and lateral nigrostriatal projections. Given the classical basal ganglia model wherein dopamine stimulates dSPNs and suppresses iSPNs through distinct dopamine receptors, dopamine might not be the primary driver of iSPN activity increasing following higher reward expectation. In contrast, outcome-related activity was affected by reward expectation in line with the classical model and reinforcement learning theory, suggesting purposive effects of reward expectation.


Assuntos
Dopamina , Motivação , Animais , Ratos , Substância Negra , Corpo Estriado , Neurônios Dopaminérgicos
7.
Radiol Phys Technol ; 16(4): 488-496, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37581714

RESUMO

This study investigated the influence of iterative reconstruction (IR) methods on computed tomography (CT) images when training convolutional neural network (CNN) models to diagnose pulmonary emphysema. To evaluate the influence of the IR algorithm on CNN, the present study comprised two steps: the comparison of noise reduction by IR algorithms using phantom examinations and the change in performance of CNN with IR algorithms using patient data. We retrospectively analyzed 97 patients. Raw CT data were reconstructed using the filtered back-projection (FBP) and adaptive statistical iterative reconstruction V (ASIR-V) algorithms with blending levels of 30%, 50%, and 70%. The models were trained using reconstructed CT images and were named the FBP, ASIR-V30, ASIR-V50, and ASIR-V70 models. The mean and the standard deviation of the CT values were 11.3 ± 21.2 at FBP, 11.0 ± 17.3 at ASIR-V30, 11.0 ± 14.4 at ASIR-V50, and 11.0 ± 11.8 at ASIR-V70. For all the evaluation metrics, the best values were obtained with the FBP model applied to the ASIR-V70 test images. The worst values were obtained with the ASIR-V70 model applied to the FBP test images. The model trained with FBP images exhibited significantly better performance than the models trained using IR images. The reduction in image noise with the IR algorithm on the test images contributed to improving the accuracy of the classification of emphysema subtypes using CNN.


Assuntos
Enfisema Pulmonar , Humanos , Enfisema Pulmonar/diagnóstico por imagem , Estudos Retrospectivos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Redes Neurais de Computação , Algoritmos , Processamento de Imagem Assistida por Computador/métodos , Doses de Radiação
8.
Curr Res Neurobiol ; 4: 100079, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37397811

RESUMO

As science and technology evolve, there is an increasing need for promotion of international scientific exchange. Collaborations, while offering substantial opportunities for scientists and benefit to society, also present challenges for those working with animal models, such as non-human primates (NHPs). Diversity in regulation of animal research is sometimes mistaken for the absence of common international welfare standards. Here, the ethical and regulatory protocols for 13 countries that have guidelines in place for biomedical research involving NHPs were assessed with a focus on neuroscience. Review of the variability and similarity in trans-national NHP welfare regulations extended to countries in Asia, Europe and North America. A tabulated resource was established to advance solution-oriented discussions and scientific collaborations across borders. Our aim is to better inform the public and other stakeholders. Through cooperative efforts to identify and analyze information with reference to evidence-based discussion, the proposed key ingredients may help to shape and support a more informed, open framework. This framework and resource can be expanded further for biomedical research in other countries.

9.
Front Aging Neurosci ; 15: 1221341, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37441679

RESUMO

Zonisamide (ZNS; 1,2-benzisoxazole-3-methanesulfonamide) was initially developed and is commonly used as an anticonvulsant drug. However, it has also shown its beneficial effects on Parkinson's disease (PD), a progressive neurodegenerative disorder caused by the loss of dopaminergic neurons in the midbrain. Recent clinical studies have suggested that ZNS can also have beneficial effects on L-DOPA-induced dyskinesia (LID), which is a major side effect of long-term L-DOPA treatments for PD. In the present study, we examined the behavioral effects of ZNS on LID in PD model mice. Acute ZNS treatment did not have any observable behavioral effects on LID. Contrastingly, chronic ZNS treatment with L-DOPA delayed the peak of LID and reduced the severity of LID before the peak but increased the duration of LID in a dose-dependent manner of ZNS compared to PD model mice treated with L-DOPA alone. Thus, ZNS appears to have both beneficial and adverse effects on LID.

10.
Cell Rep ; 40(10): 111309, 2022 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-36070693

RESUMO

Dysfunctional dopamine signaling is implicated in various neuropsychological disorders. Previously, we reported that dopamine increases D1 receptor (D1R)-expressing medium spiny neuron (MSN) excitability and firing rates in the nucleus accumbens (NAc) via the PKA/Rap1/ERK pathway to promote reward behavior. Here, the results show that the D1R agonist, SKF81297, inhibits KCNQ-mediated currents and increases D1R-MSN firing rates in murine NAc slices, which is abolished by ERK inhibition. In vitro ERK phosphorylates KCNQ2 at Ser414 and Ser476; in vivo, KCNQ2 is phosphorylated downstream of dopamine signaling in NAc slices. Conditional deletion of Kcnq2 in D1R-MSNs reduces the inhibitory effect of SKF81297 on KCNQ channel activity, while enhancing neuronal excitability and cocaine-induced reward behavior. These effects are restored by wild-type, but not phospho-deficient KCNQ2. Hence, D1R-ERK signaling controls MSN excitability via KCNQ2 phosphorylation to regulate reward behavior, making KCNQ2 a potential therapeutical target for psychiatric diseases with a dysfunctional reward circuit.


Assuntos
Dopamina , Canal de Potássio KCNQ2 , Transtornos Mentais , Proteínas do Tecido Nervoso , Animais , Dopamina/metabolismo , Canal de Potássio KCNQ2/metabolismo , Transtornos Mentais/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Fosforilação , Receptores de Dopamina D1/metabolismo , Recompensa
11.
Cereb Cortex Commun ; 3(2): tgac022, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35769971

RESUMO

Functional magnetic resonance imaging (fMRI) is a promising approach for the simultaneous and extensive scanning of whole-brain activities. Optogenetics is free from electrical and magnetic artifacts and is an ideal stimulation method for combined use with fMRI. However, the application of optogenetics in nonhuman primates (NHPs) remains limited. Recently, we developed an efficient optogenetic intracortical microstimulation method of the primary motor cortex (M1), which successfully induced forelimb movements in macaque monkeys. Here, we aimed to investigate how optogenetic M1 stimulation causes neural modulation in the local and remote brain regions in anesthetized monkeys using 7-tesla fMRI. We demonstrated that optogenetic stimulation of the M1 forelimb and hindlimb regions successfully evoked robust direct and remote fMRI activities. Prominent remote activities were detected in the anterior and posterior lobes in the contralateral cerebellum, which receive projections polysynaptically from the M1. We further demonstrated that the cerebro-cerebellar projections from these M1 regions were topographically organized, which is concordant with the somatotopic map in the cerebellar cortex previously reported in macaques and humans. The present study significantly enhances optogenetic fMRI in NHPs, resulting in profound understanding of the brain network, thereby accelerating the translation of findings from animal models to humans.

12.
Sci Rep ; 12(1): 6493, 2022 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-35444245

RESUMO

In parkinsonism, subthalamic nucleus (STN) electrical deep brain stimulation (DBS) improves symptoms, but may be associated with side effects. Adaptive DBS (aDBS), which enables modulation of stimulation, may limit side effects, but limited information is available about clinical effectiveness and efficaciousness. We developed a brain-machine interface for aDBS, which enables modulation of stimulation parameters of STN-DBS in response to γ2 band activity (80-200 Hz) of local field potentials (LFPs) recorded from the primary motor cortex (M1), and tested its effectiveness in parkinsonian monkeys. We trained two monkeys to perform an upper limb reaching task and rendered them parkinsonian with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Bipolar intracortical recording electrodes were implanted in the M1, and a recording chamber was attached to access the STN. In aDBS, the M1 LFPs were recorded, filtered into the γ2 band, and discretized into logic pulses by a window discriminator, and the pulses were used to modulate the interval and amplitude of DBS pulses. In constant DBS (cDBS), constant stimulus intervals and amplitudes were used. Reaction and movement times during the task were measured and compared between aDBS and cDBS. The M1-γ2 activities were increased before and during movements in parkinsonian monkeys and these activities modulated the aDBS pulse interval, amplitude, and dispersion. With aDBS and cDBS, reaction and movement times were significantly decreased in comparison to DBS-OFF. The electric charge delivered was lower with aDBS than cDBS. M1-γ2 aDBS in parkinsonian monkeys resulted in clinical benefits that did not exceed those from cDBS. However, M1-γ2 aDBS achieved this magnitude of benefit for only two thirds of the charge delivered by cDBS. In conclusion, M1-γ2 aDBS is an effective therapeutic approach which requires a lower electrical charge delivery than cDBS for comparable clinical benefits.


Assuntos
Estimulação Encefálica Profunda , Córtex Motor , Transtornos Parkinsonianos , Núcleo Subtalâmico , Animais , Estimulação Encefálica Profunda/métodos , Haplorrinos , Córtex Motor/fisiologia , Núcleo Subtalâmico/fisiologia
13.
Nat Commun ; 13(1): 2233, 2022 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-35468893

RESUMO

The subthalamic nucleus projects to the external and internal pallidum, the modulatory and output nuclei of the basal ganglia, respectively, and plays an indispensable role in controlling voluntary movements. However, the precise mechanism by which the subthalamic nucleus controls pallidal activity and movements remains elusive. Here, we utilize chemogenetics to reversibly reduce neural activity of the motor subregion of the subthalamic nucleus in three macaque monkeys (Macaca fuscata, both sexes) during a reaching task. Systemic administration of chemogenetic ligands prolongs movement time and increases spike train variability in the pallidum, but only slightly affects firing rate modulations. Across-trial analyses reveal that the irregular discharges in the pallidum coincides with prolonged movement time. Reduction of subthalamic activity also induces excessive abnormal movements in the contralateral forelimb, which are preceded by subthalamic and pallidal phasic activity changes. Our results suggest that the subthalamic nucleus stabilizes pallidal spike trains and achieves stable movements.


Assuntos
Núcleo Subtalâmico , Animais , Gânglios da Base , Globo Pálido , Haplorrinos , Movimento
14.
eNeuro ; 9(2)2022.
Artigo em Inglês | MEDLINE | ID: mdl-35140075

RESUMO

The basal ganglia (BG) are crucial for a variety of motor and cognitive functions. Changes induced by persistent low-dopamine (e.g., in Parkinson's disease; PD) result in aberrant changes in steady-state population activity (ß band oscillations) and the transient response of the BG. Typically, a brief cortical stimulation results in a triphasic response in the substantia nigra pars reticulata (SNr; an output of the BG). The properties of the triphasic responses are shaped by dopamine levels. While mechanisms underlying aberrant steady state activity are well studied, it is still unclear which BG interactions are crucial for the aberrant transient responses in the BG. Moreover, it is also unclear whether mechanisms underlying the aberrant changes in steady-state activity and transient response are the same. Here, we used numerical simulations of a network model of BG to identify the key factors that determine the shape of the transient responses. We show that an aberrant transient response of the SNr in the low-dopamine state involves changes in the direct pathway and the recurrent interactions within the globus pallidus externa (GPe) and between GPe and subthalamic nucleus (STN). However, the connections from D2-type spiny projection neurons (D2-SPN) to GPe are most crucial in shaping the transient response and by restoring them to their healthy level, we could restore the shape of transient response even in low-dopamine state. Finally, we show that the changes in BG that result in aberrant transient response are also sufficient to generate pathologic oscillatory activity in the steady state.


Assuntos
Doença de Parkinson , Núcleo Subtalâmico , Gânglios da Base/fisiologia , Dopamina/metabolismo , Globo Pálido , Humanos , Doença de Parkinson/metabolismo , Núcleo Subtalâmico/fisiologia
15.
J Neurosci Methods ; 372: 109532, 2022 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-35182602

RESUMO

BACKGROUND: Spike trains are series of interspike intervals in a specific order that can be characterized by their probability distributions and order in time which refer to the concepts of rate and spike timing features. Periodic structure in the spike train can be reflected in oscillatory activities. Thus, there is a direct link between oscillator activities and the spike train. The proposed methods are to investigate the dependency of emerging oscillatory activities to the rate and the spike timing features. METHOD: First, the circular statistics methods were compared to Fast Fourier Transform for best estimation of spectra. Second, two statistical tests were introduced to help make decisions regarding the dependency of spectrum, or individual frequencies, onto rate and spike timing. Third, the methodology is applied to in-vivo recordings of basal ganglia neurons in mouse, primate, and human. Finally, this novel framework is shown to allow the investigation of subsets of spikes contributing to individual oscillators. RESULTS: Use of circular statistical methods, in comparison to FFT, minimizes spectral leakage. Using virtual spike trains, the Rate versus Timing Dependency Spectrum Test (or RTDs-Test) permits identifying spectral spike trains solely dependent on the rate feature from those that are also dependent on the spike timing feature. Similarly, the Rate versus Timing Dependency Frequency Test (or RTDf-Test), allows to identify individual oscillators with partial dependency on spike timing. Dependency on spike timing was found for all in-vivo recordings but only in few frequencies. The mapping in frequency and time of dependencies showed a dynamical process that may be organizing the basal ganglia function. CONCLUSIONS: The methodology may improve our understanding of the emergence of oscillatory activities and, possibly, the relation between oscillatory activities and circuitry functions.


Assuntos
Gânglios da Base , Neurônios , Potenciais de Ação/fisiologia , Animais , Camundongos , Modelos Neurológicos , Neurônios/fisiologia , Probabilidade
17.
Cereb Cortex ; 31(12): 5363-5380, 2021 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-34268560

RESUMO

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by dopamine deficiency. To elucidate network-level changes through the cortico-basal ganglia pathways in PD, we recorded neuronal activity in PD monkeys treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. We applied electrical stimulation to the motor cortices and examined responses in the internal (GPi) and external (GPe) segments of the globus pallidus, the output and relay nuclei of the basal ganglia, respectively. In the normal state, cortical stimulation induced a triphasic response composed of early excitation, inhibition, and late excitation in the GPi and GPe. In the PD state, cortically evoked inhibition in the GPi mediated by the cortico-striato-GPi "direct" pathway was largely diminished, whereas late excitation in the GPe mediated by the cortico-striato-GPe-subthalamo (STN)-GPe pathway was elongated. l-DOPA treatment ameliorated PD signs, particularly akinesia/bradykinesia, and normalized cortically evoked responses in both the GPi and GPe. STN blockade by muscimol injection ameliorated the motor deficit and unmasked cortically evoked inhibition in the GPi. These results suggest that information flow through the direct pathway responsible for the initiation of movements is largely reduced in PD and fails to release movements, resulting in akinesia/bradykinesia. Restoration of the information flow through the direct pathway recovers execution of voluntary movements.


Assuntos
Doença de Parkinson , Gânglios da Base , Globo Pálido/fisiologia , Humanos , Levodopa/farmacologia , Vias Neurais/fisiologia
18.
J Neurosci ; 41(25): 5502-5510, 2021 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-34001630

RESUMO

The substantia nigra pars reticulata (SNr) is the output station of the basal ganglia and receives cortical inputs by way of the following three basal ganglia pathways: the cortico-subthalamo (STN)-SNr hyperdirect, the cortico-striato-SNr direct, and the cortico-striato-external pallido-STN-SNr indirect pathways. Compared with the classical direct and indirect pathways via the striatum, the functions of the hyperdirect pathway remain to be fully elucidated. Here we used a photodynamic technique to selectively eliminate the cortico-STN projection in male mice and observed neuronal activity and motor behaviors in awake conditions. After cortico-STN elimination, cortically evoked early excitation in the SNr was diminished, while the cortically evoked inhibition and late excitation, which are delivered through the direct and indirect pathways, respectively, were unchanged. In addition, locomotor activity was significantly increased after bilateral cortico-STN elimination, and apomorphine-induced ipsilateral rotations were observed after unilateral cortico-STN elimination, suggesting that cortical activity was increased. These results are compatible with the notion that the cortico-STN-SNr hyperdirect pathway quickly conveys cortical excitation to the output station of the basal ganglia, resets or suppresses the cortical activity related to ongoing movements, and prepares for the forthcoming movement.SIGNIFICANCE STATEMENT The basal ganglia play a pivotal role in the control of voluntary movements, and their malfunctions lead to movement disorders, such as Parkinson's disease and dystonia. Understanding their functions is important to find better treatments for such diseases. Here we used a photodynamic technique to selectively eliminate the projection from the motor cortex to the subthalamic nucleus, the input station of the basal ganglia, and found greatly reduced early excitatory signals from the cortex to the output station of the basal ganglia and motor hyperactivity. These results suggest that the neuronal signals through the cortico-subthalamic hyperdirect pathway reset or suppress ongoing movements and that blockade of this pathway may be beneficial for Parkinson's disease, which is characterized by oversuppression of movements.


Assuntos
Hipercinese/fisiopatologia , Córtex Motor/fisiologia , Vias Neurais/fisiologia , Núcleo Subtalâmico/fisiologia , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BL
19.
J Neurosci ; 41(12): 2668-2683, 2021 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-33563724

RESUMO

l-3,4-dihydroxyphenylalanine (l-DOPA) is an effective treatment for Parkinson's disease (PD); however, long-term treatment induces l-DOPA-induced dyskinesia (LID). To elucidate its pathophysiology, we developed a mouse model of LID by daily administration of l-DOPA to PD male ICR mice treated with 6-hydroxydopamine (6-OHDA), and recorded the spontaneous and cortically evoked neuronal activity in the external segment of the globus pallidus (GPe) and substantia nigra pars reticulata (SNr), the connecting and output nuclei of the basal ganglia, respectively, in awake conditions. Spontaneous firing rates of GPe neurons were decreased in the dyskinesia-off state (≥24 h after l-DOPA injection) and increased in the dyskinesia-on state (20-100 min after l-DOPA injection while showing dyskinesia), while those of SNr neurons showed no significant changes. GPe and SNr neurons showed bursting activity and low-frequency oscillation in the PD, dyskinesia-off, and dyskinesia-on states. In the GPe, cortically evoked late excitation was increased in the PD and dyskinesia-off states but decreased in the dyskinesia-on state. In the SNr, cortically evoked inhibition was largely suppressed, and monophasic excitation became dominant in the PD state. Chronic l-DOPA treatment partially recovered inhibition and suppressed late excitation in the dyskinesia-off state. In the dyskinesia-on state, inhibition was further enhanced, and late excitation was largely suppressed. Cortically evoked inhibition and late excitation in the SNr are mediated by the cortico-striato-SNr direct and cortico-striato-GPe-subthalamo-SNr indirect pathways, respectively. Thus, in the dyskinesia-on state, signals through the direct pathway that release movements are enhanced, while signals through the indirect pathway that stop movements are suppressed, underlying LID.SIGNIFICANCE STATEMENT Parkinson's disease (PD) is caused by progressive loss of midbrain dopaminergic neurons, characterized by tremor, rigidity, and akinesia, and estimated to affect around six million people world-wide. Dopamine replacement therapy is the gold standard for PD treatment; however, control of symptoms using l-3,4-dihydroxyphenylalanine (l-DOPA) becomes difficult over time because of abnormal involuntary movements (AIMs) known as l-DOPA-induced dyskinesia (LID), one of the major issues for advanced PD. Our electrophysiological data suggest that dynamic changes in the basal ganglia circuitry underlie LID; signals through the direct pathway that release movements are enhanced, while signals through the indirect pathway that stop movements are suppressed. These results will provide the rationale for the development of more effective treatments for LID.


Assuntos
Gânglios da Base/fisiopatologia , Córtex Cerebral/fisiopatologia , Modelos Animais de Doenças , Discinesia Induzida por Medicamentos/fisiopatologia , Levodopa/toxicidade , Transmissão Sináptica/fisiologia , Animais , Gânglios da Base/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos ICR , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Transmissão Sináptica/efeitos dos fármacos
20.
Proc Natl Acad Sci U S A ; 118(3)2021 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-33397806

RESUMO

Physiological functioning and homeostasis of the brain rely on finely tuned synaptic transmission, which involves nanoscale alignment between presynaptic neurotransmitter-release machinery and postsynaptic receptors. However, the molecular identity and physiological significance of transsynaptic nanoalignment remain incompletely understood. Here, we report that epilepsy gene products, a secreted protein LGI1 and its receptor ADAM22, govern transsynaptic nanoalignment to prevent epilepsy. We found that LGI1-ADAM22 instructs PSD-95 family membrane-associated guanylate kinases (MAGUKs) to organize transsynaptic protein networks, including NMDA/AMPA receptors, Kv1 channels, and LRRTM4-Neurexin adhesion molecules. Adam22ΔC5/ΔC5 knock-in mice devoid of the ADAM22-MAGUK interaction display lethal epilepsy of hippocampal origin, representing the mouse model for ADAM22-related epileptic encephalopathy. This model shows less-condensed PSD-95 nanodomains, disordered transsynaptic nanoalignment, and decreased excitatory synaptic transmission in the hippocampus. Strikingly, without ADAM22 binding, PSD-95 cannot potentiate AMPA receptor-mediated synaptic transmission. Furthermore, forced coexpression of ADAM22 and PSD-95 reconstitutes nano-condensates in nonneuronal cells. Collectively, this study reveals LGI1-ADAM22-MAGUK as an essential component of transsynaptic nanoarchitecture for precise synaptic transmission and epilepsy prevention.


Assuntos
Proteínas ADAM/genética , Epilepsia/genética , Guanilato Quinases/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas do Tecido Nervoso/genética , Transmissão Sináptica/genética , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Proteínas de Ligação ao Cálcio/genética , Modelos Animais de Doenças , Epilepsia/patologia , Epilepsia/prevenção & controle , Técnicas de Introdução de Genes , Hipocampo/metabolismo , Hipocampo/patologia , Humanos , Proteínas de Membrana/genética , Camundongos , Moléculas de Adesão de Célula Nervosa/genética , Receptores de AMPA/genética , Receptores de N-Metil-D-Aspartato/genética , Superfamília Shaker de Canais de Potássio/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA