The vast majority of patients have been implanted with bilateral electrodes, and the targets were the subthalamic nucleus, the thalamus and the internal segment of globus pallidus. 
High-frequency stimulation (HFS) of the subthalamic nucleus (STN) or internal segment of the globus pallidus is a clinically successful treatment for the motor symptoms of Parkinson's disease.
Deep brain stimulation (DBS) was applied in the internal segment of the globus pallidus (GPi) to treat dystonia in 10 patients.
Parkinson's disease (PD) patients with prior radio-frequency lesions in the internal segment of the globus pallidus (GPi, pallidotomy), whose symptoms have deteriorated, may be candidates for further invasive treatment such as subthalamic deep brain stimulation (STN DBS).
Output from the entopeduncular nucleus, the feline equivalent of the internal segment of the globus pallidus, provides a modest direct input to the red nucleus as well as a more substantial indirect input via projections to the zona incerta and the fields of Forel.
Yet there is one undeniable observation: lesioning or high-frequency stimulation of the internal segment of the globus pallidus (GP) ameliorates dystonic symptoms.
The therapeutic effectiveness of deep brain stimulation (DBS) of the subthalamic nucleus (STN) may arise through its effects on inhibitory basal ganglia outputs, including those from the internal segment of the globus pallidus (GPi).
The internal segment of the globus pallidus (GPi) receives motor-related cortical signals mainly through the striatum, the external segment of the globus pallidus (GPe) and the subthalamic nucleus (STN).
BACKGROUND: Several subcortical structures have been targeted for surgical treatment of dystonia, including motor thalamus, internal segment of globus pallidus (GPi), and more recently, the subthalamic nucleus (STN).
OBJECTIVE: To describe the results and long-term follow-up after functional surgery of the internal segment of the globus pallidus (GPi) in 10 patients with primary generalized dystonia.
Current theories of basal ganglia (BG) function based on suppression of activity in the ventrolateral thalamic-cortical circuits by the globus pallidus internal segment are inconsistent with accumulating evidence, demonstrating the need for reconsideration.
We found that both of these cortical areas are the targets of disynaptic projections from the dentate nucleus of the cerebellum and from the internal segment of the globus pallidus (GPi).
BACKGROUND AND PURPOSE: Linear hyperintensity along the medial margin of the internal segment of the globus pallidus (GPi) on T2-weighted images from patients with Machado-Joseph disease (MJD) was recently reported.
They demonstrate a consistent pattern characterized by damage to the globus pallidus (particularly the internal segment) with sparing of the substantia nigra pars compacta and the absence of Lewy bodies.
In addition, DBS research demonstrates the need to re-consider many hypotheses regarding basal ganglia physiology and pathophysiology such as the notion that increased activity in the globus pallidus internal segment is causal to Parkinson's disease symptoms.
We suggest that modulation of output of the internal segment of the globus pallidus by STN DBS may drive the effect of STN DBS on memory guided force control..
We recorded extracellular single unit discharges of globus pallidus internal segment (GPi) neurons in monkeys performing a visually driven forearm rotation movement task in order to quantify how discharge patterns changed in relation to kinematic parameters.
Together with the internal segment of the globus pallidus (GP(i)), the pars reticulata of the substantia nigra (SNr) provides a main output nucleus of the basal ganglia (BG) where the final stage of information processing within this system takes place.
The internal segment of the globus pallidus (GP(i)) gathers many bits of information including movement-related activity from the striatum, external segment of the globus pallidus (GP(e)), and subthalamic nucleus (STN), and integrates them.
Such activity correlates with the level of dystonic muscle activity and is concentrated in the internal segment of the globus pallidus, which is also the optimum surgical target in dystonia.
Intraoperative physiologic evaluation revealed decreased firing rates in the internal segment of the globus pallidus. RESULTS: Deep brain stimulation of the internal segment of the globus pallidus resulted in resolution of the dyskinesia.
Similarly, stimulation of the subthalamic nucleus or the internal segment of the globus pallidus can substantially reduce bradykinesia, rigidity, tremor, and gait difficulties in people with PD.
In the dorsal striatum, MSNs can be distinguished based on the organization of their connectivity to substantia nigra pars reticulata (SNpr) and internal segment of the globus pallidus (GPi), which, in turn, control thalamocortical neurons.
In Parkinson's disease, neurons of the internal segment of the globus pallidus (GPi) display the low-frequency tremor-related oscillations.
Similarly, stimulation of the subthalamic nucleus or the internal segment of the globus pallidus can substantially reduce bradykinesia, rigidity, tremor, and gait difficulties in people with PD.
Ten arrays have been implanted into the STN of domestic cats, and one into the internal segment of the globus pallidus, for 140-415 days.
Fractal analysis was applied to human pallidal neuronal spike trains recorded from patients with Parkinson's disease during ablative surgery of the internal segment of the globus pallidus. We observed fractal persistent correlation in the fluctuation of the interspike intervals of neuronal spike trains recorded in the internal segment of the globus pallidus both before and after the administration of dopamine agonist apomorphine. We conclude that robust fractal dynamics can be observed in single neurons in the human CNS, indicating that human neuronal dynamics of the internal segment of the globus pallidus are essentially a nonlinear and nonequilibrium process, with a long-range correlation or memory extending across many time scales.
Behavioral assessments of bradykinesia and akinesia as well as single neuron recordings in the internal segment of the globus pallidus (GPi) were performed in both monkeys before and after ablating the sensorimotor portion of GPe.
Electrolytic lesions were placed in the left internal segment of the globus pallidus.
A patient with myoclonus-dystonia syndrome was treated by implanting electrodes in the internal segment of the globus pallidus (GPi) and applying deep brain stimulation.
Neurons in the external and internal segment of the globus pallidus (GPe and GPi, respectively) receive substantial GABAergic inputs from the striatum and through axon collaterals of neighboring pallidal neurons.
With faster rates of RNG, the controls showed rCBF increase in the right internal segment of globus pallidus (GPi) and a decrease in frontal cortex.
Our new finding on magnetic resonance imaging (MRI) of Machado-Joseph disease (MJD) patients indicates degeneration of the lenticular fasciculus (LF), a major outflow of the internal segment of the globus pallidus (GPi). In the autopsy case, abnormal linear high intensity areas were observed along the bilateral medial margins of the internal segments of the GPi on T2 weighted, FLAIR, and proton density images, but not on T1 weighted images.
In this intraoperative microdialysis study, we found elevated cGMP extracellular concentrations in the internal segment of the globus pallidus, despite negligible changes in glutamate levels, during a clinically effective STN-DBS.
The volume for the GP, GPe, and internal segment (GPi) did not differ between groups..
Deep brain stimulation of globus pallidus internal segment shows remarkable effect on DYT1.
The mean spontaneous firing rate of neurons in the internal segment of the globus pallidus internus (GPii) was significantly lower in MSA than in PD patients.
(4) Substance P expression was up-regulated in the internal segment of the globus pallidus (GPi), but remained unchanged in substantia nigra (SN).
In contrast, movements that require the internal regulation of the rate of change of force are associated with increased metabolic demand from the subthalamic nucleus and internal segment of the globus pallidus..
The rationale of targeting specific structures within basal ganglia such as the subthalamic nucleus (STN) or the internal segment of the globus pallidus (GPi) is strongly supported by the current knowledge of the basal ganglia pathophysiology, which is derived from extensive experimental work and which provides the theoretical basis for surgical therapy in PD.
By contrast, the loss in the striatal projection system to the internal segment of globus pallidus proceeded more gradually.
The organization of the pallidofugal fiber system originating from the internal segment of the globus pallidus (GPi) in cynomolgus monkeys (Macaca fascicularis) was studied by means of a single-axon tracing method.
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or the internal segment of the globus pallidus (GPi) has recently been recognized as an important form of intervention for alleviating motor symptoms associated with Parkinson's disease, but the mechanism underlying its effectiveness remains unknown.
The subthalamic nucleus (STN) and the internal segment of the globus pallidus (GPi) are targeted for the treatment of advanced Parkinson's disease.
It has been shown in primates that the activity of many neurons in one of the basal ganglia output nuclei, the internal segment of the globus pallidus, changes with active or passive movements.
The subthalamic nucleus (STN), a major component of the basal ganglia, exerts an excitatory influence on the output structures of this system i.e., the substantia nigra pars reticulata (SNR) and the internal segment of the globus pallidus.
According to the results of the simulation, for transmission of the STN oscillatory activity to the cortex, the STN oscillatory activity has to be transmitted simultaneously to the thalamus via STN-internal segment of the globus pallidus (GPi)-thalamus and STN-GPe-GPi-thalamus pathways.
Inactivation of the subthalamic nucleus (STN) or the internal segment of the pallidum (GPi)/entopeduncular nucleus (EP) by deep brain stimulation or lesioning alleviates clinical manifestations of Parkinson's disease (PD) as well as reducing the side-effects of levodopa treatment.
A central origin of tremor could arise either from a rhythmic activity of the internal segment of the globus pallidus (GPi) or from a structure such as the thalamus, outside the basal ganglia.
The internal segment of globus pallidus and substantia nigra reticulata are the output nuclei.
Deep brain stimulation (DBS) in the subthalamic nucleus (STN) and the internal segment of the globus pallidus (GPi) is increasingly being used for the treatment of advanced Parkinson's disease (PD).
Currently, bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) or the internal segment of the globus pallidus (GPi) is the preferred option (and is approved by the US Food and Drug Administration) for the surgical treatment of PD.
In this (18)F-dopa positron emission tomography study, we demonstrate compensatory changes in PD in another midbrain dopamine projection to the basal ganglia, the nigropallidal projection to the internal segment of the globus pallidus (GPi).
In labeling experiments, four macaque monkeys (Macaca mulatta) received injections of biotinylated dextran amine and wheat germ agglutinin conjugated to horseradish peroxidase into the cerebellar nuclei or internal segment of the globus pallidus and cervical segments of the spinal cord, respectively.
After MPTP treatment, firing rates decreased in the external segment of the globus pallidus (GP(e)) and increased in the internal segment (GP(i)).
All of these prefrontal areas were found to be targets of basal-ganglia output that originated in the internal segment of the globus pallidus (GPi) and/or the pars reticulata of the substantia nigra (SNpr).
In adult-onset Huntington's disease (HD), striatal projection neurons are much more vulnerable than striatal interneurons, but even striatal projection neurons show differences in their vulnerability, with the striatal projection neurons projecting to the internal segment of the globus pallidus being the least vulnerable.
Altered activity of the entopeduncular nucleus, the rodent homologue of the globus pallidus internal segment in primates, is thought to mediate behavioral consequences of midbrain dopamine depletion in rodents. Additionally, inhibition of firing rates by D(1) or combined D(1)/D(2) receptor activation indicated that dopamine agonists affected the overall level of entopeduncular activity in a manner similar to that found in the substantia nigra pars reticulata and globus pallidus internal segment after dopamine neuron lesion. These data demonstrate that lesion of the nigrostriatal tract leads to modifications of several aspects of firing pattern in the rodent entopeduncular nucleus and so expand on similar findings in the rodent substantia nigra pars reticulata and in the globus pallidus internal segment in humans and nonhuman primates.
The purpose of the present study was to determine the interrelationship between the thalamic afferents arising from the cerebellum (Cb) and the internal segment of the globus pallidus (GPi) with the neurons projecting to the primary motor cortex (MI) and to the supplementary motor area (SMA).
Loss of dopaminergic innervation leads to hyperactivity in the internal segment of the globus pallidus (GPi), the main output nucleus of the basal ganglia and to a profound disturbance in the function of motor circuits.
Neurturin only protected gamma-aminobutyric acid (GABA)/enkephalinergic neurons that project to the external segment of the globus pallidus, whereas GDNF exerts its effects on GABA/substance P positive neurons, which project to the substantia nigra pars compacta and the internal segment of the globus pallidus.
The internal segment of the globus pallidus (GPi) is being targeted in neurosurgical procedures to treat Parkinson's disease and dystonia.
The comparable effect of stimulation to ablation in the thalamus on tremor, and in the subthalamic nucleus (STN) and internal segment of the globus pallidus (GPi) on the motor signs associated with PD, have led many investigators to conclude that DBS acts to suppress neuronal activity, decreasing output from the stimulated site.
Some reports have hypothesised that the loss of subthalamic nucleus control on the internal segment of the globus pallidus, followed by the disinhibition of the thalamus may contribute to chorea.
The direct pathway disinhibits the powerful inhibition of the internal segment of the globus pallidus/substantia nigra pars reticulata upon thalamic ventrolateral nuclei with a net result of facilitatory influence upon the motor cortex.
Chorea in the lower limb was reduced after a neurosurgical lesion in the medial portion of the sensorimotor territory of the internal segment of the globus pallidus, and chorea in the upper limb disappeared after an additional lesion in the lateral portion of that same area.
In order to examine whether the basal ganglia are involved in arbitrary visuomotor association, we recorded neuronal activity in the internal segment of the globus pallidus (GPi) of monkeys during a conditional visuomotor learning task.
Synaptic information travels through the basal ganglia using distinct pathways from the input structure, the striatum, to the output nuclei, the substantia nigra pars reticulata and the globus pallidus internal segment.
The STN is a very small nucleus (140 cubic mm or 0.02% of the total brain volume, consisting of approximately 300,000 neurons) which is disinhibited in PD, leading to pathological excitation of its targets, the internal segment of the globus pallidus (GPi) and substantia nigra pars reticulata (SNpr).
The internal segment of the globus pallidus, the subthalamic nucleus, and the cerebellar dentate nucleus showed mild to moderate neuronal loss.
This study examines the effect of apomorphine (APO), a nonselective D(1)- and D(2)-dopamine receptor agonist, on the firing activity of neurons in the subthalamic nucleus (STN) and internal segment of the globus pallidus (GPi) in patients with Parkinson's disease (PD).
Twenty-four participants underwent unilateral pallidotomy, 10 underwent deep brain stimulating electrode implantation of the internal segment of the globus pallidus, 4 underwent thalamic deep brain stimulating electrode implantation, and 1 underwent left thalamotomy.
Second, good matches between model globus pallidus external segment output and globus pallidus internal segment and substantia nigra reticulata area output, and neurophysiological data, have been found which are indicative of common architectural features in the model and biological basal ganglia.
Stimulation of the internal segment of the globus pallidus (GPi) or the subthalamic nucleus (STN) can improve tremor, rigidity, bradykinesia and gait disturbances in Parkinson's disease and improve the day-to-day activities of patients with these disabling symptoms.
Neuronal recording during dystonia revealed that the mean firing rates were low in both the internal and external segments of the globus pallidus, and that firing was irregular in the internal segment of the globus pallidus, compared with firing patterns in offstate parkinsonian patients without dystonia.
The isolated lesion of the internal segment of the GP was the presumed cause of the dystonia, acting through an alteration in thalamic inhibition.
Altered activity in one of the output nuclei of the basal ganglia, the internal segment of the globus pallidus, is known to play an important role in the generation of parkinsonism.
Extracellular discharges from single neurons in the internal segment of the globus pallidus (GPi) were recorded and analyzed for rate changes associated with visually guided forearm rotations to four different targets.
Intraoperative neuronal recording in a patient with off-period dystonia revealed that the mean firing rates were considerably low in both the internal and external segments of the globus pallidus and that firing was irregular in the internal segment of the globus pallidus when dystonia developed, as compared with firing patterns in off-state parkinsonian patients without dystonia. Ablation and stimulation of the internal segment of the globus pallidus can abolish both types of dystonia by blocking the abnormal activity of pallidal neurons..
Furthermore, immunopositive nerve fibers were also observed, and numerous axons were intensely immunolabeled in the internal segment of the globus pallidus and the pars reticulata of the substantia nigra.
All lesions involved the internal segment of the GP. CONCLUSION: These cases emphasise the importance of the GP, particularly its internal segment, in the pathophysiology of dystonia..
Virtually the whole of the cortical mantle projects in a topographic manner onto the striatum, this cortical information is 'processed' within the striatum and passed via the so-called direct and indirect pathways to the output nuclei of the basal ganglia, the internal segment of the globus pallidus and the substantia nigra pars reticulata.
Similarly, the internal segment of the globus pallidus (GPi) and the substantia nigra pars reticulata (SNpr) form the main nuclei for exit from the circuit and have an inhibitory effect on the pre-motor neurones of the ventral lamina of the thalamus.
Neurosurgical treatment of Parkinson's disease (PD) frequently employs chronic high-frequency deep brain stimulation (DBS) within the internal segment of globus pallidus (GPi) and can very effectively reduce L-dopa-induced dyskinesias and bradykinesia, but the mechanisms are unknown.
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or the internal segment of the globus pallidus (GPi) improves Parkinson's disease and increases frontal blood flow.
MPTP induced a decrease (-40%) of (125)I-CGP 64213 binding to GABA(B) receptors in the substantia nigra pars compacta (SNpc) and an increase (+29%) in the internal segment of the globus pallidus (GPi).
Based on studies in animal models and humans with hyperkinetic movement disorders, it is postulated that dyskinesias develop as the result of a combination of excessive reductions in the mean discharge rate, altered patterns and increased synchronization of neurons in the internal segment of the globus pallidus.
On the other hand, gamma-aminobutyric acid (GABA)A binding was increased in the internal segment of the globus pallidus of dyskinetic MPTP monkeys.
This paper highlights the neuropsychological sequelae of posteroventral pallidotomy (PVP) and deep brain stimulation (DBS) of the subthalamic nucleus (STN) and the internal segment of the globus pallidus (GPi) at 3/6 months postoperatively.
The grafted neurons also send efferents to the primary striatal targets, including the globus pallidus (GP, the rodent homologue of the external segment of the globus pallidus) and the entopeduncular nucleus (EP, the rodent homologue of the internal segment of the globus pallidus).
Lesions surgically made in the internal segment of the posteroventral globus pallidus (Gpi) reduce many medically intractable symptoms in patients with Parkinson's disease.
The down-regulation of GluR1 expression in the output nuclei of the basal ganglia, the internal segment of the globus pallidus and the substantia nigra pars reticulata, may be a compensation for the overactive glutamatergic input from subthalamic nucleus, which arises after striatal dopamine denervation.
Based on their axonal targets, four distinct types of GPe projection neurons have been identified: 1) neurons that project to the internal segment of the globus pallidus (GPi), the subthalamic nucleus (STN), and the substantia nigra, pars reticulata (SNr; 13.2%); 2) neurons that target the GPi and the STN (18.4%); 3) neurons that project to the STN and the SNr (52.6%); and 4) neurons that target the striatum (15.8%).
In the analyzed brain regions, conspicuously intense SP-like immunoreactivity was observed in the substantia nigra and the internal segment of the globus pallidus. SP-like immunoreactive intensity in the internal segment of the globus pallidus, which was lower than that in the substantia nigra, was approximately twice as high as that in the external segment of the globus pallidus. Very intense immunoreactivity was localized at the most medial area of the internal segment of the globus pallidus.
The functional status of the globus pallidus internal segment (GPi) plays a key role in mediating the effects of antiparkinsonian drugs.
An important factor that has played a role in this development is the recent understanding of the functional anatomy of the basal ganglia including a knowledge of the changes in the activities of neurons in the internal segment of the globus pallidus (Gpi) and the subthalamic nucleus (STN) in Parkinson's disease as well as the knowledge of the presence of segregated functional loops within the basal ganglia which include a sensory-motor loop that involves the posteromedial globus pallidus rather than the anterior GPi where earlier pallidotomy lesions had been made.
Lesions are centred at sites in the internal segment of the globus pallidus at least 3 mm from these structures, to avoid injury to them during pallidotomy..
There have been few similar structural studies of the other major basal ganglia output, the internal segment of the globus pallidus.
Systemic injections of the dopamine antagonist haloperidol (0.1-2.5 mg/kg) induced a dose dependent increase in Fos-like immunoreactivity (FLI) in the internal segment of the globus pallidus (GPi) and in the substantia nigra (SN) of cynomolgus monkeys.
MPTP treatment induced a decrease of 3H-flunitrazepam binding in the medial anterior part of caudate-putamen and an increase in the internal segment of globus pallidus (GPi) which was in general unchanged by pulsatile or continuous SKF 82958 administration.
The responses of neurons in the internal segment of the globus pallidus to passive and active movements were also evaluated. Given the improvement in dystonic and hemiballistic movements in these patients after ablation of the sensorimotor portion of the internal segment of the globus pallidus, we suggest that pallidotomy can be an effective treatment for patients with dystonia and also for patients with medically intractable hemiballismus.
Neurons in the internal segment of the globus pallidus (GPi) oscillate at approximately the frequency of parkinsonian tremor.
Indeed, the nigrostriatal denervation induces a hyper-activity of the output structures of the basal ganglia (internal segment of the globus pallidus and substantia nigra pars reticulata), as demonstrated in various animal models of the disease.
The neuronal activity in the motor portion of one of these output nuclei, the internal segment of the globus pallidus (GPi), has been characterized in detail in intact and parkinsonian animals, but the neuronal activity in the second major basal ganglia output nucleus, the substantia nigra pars reticulata (SNr), has received far less attention.
On the contrary, the stimulation in the internal segment (GPi) produced complex sequence of changes.
In the present study, we used dual microelectrodes to record tremor-related neuronal activity from eight sites in the internal segment of the globus pallidus (GPi) from an awake Parkinson's disease patient undergoing stereotaxic pallidotomy.
The dense presence of CB1 receptors in the cerebellum and in the basal ganglia, especially at the outflow nuclei (substantia nigra and the internal segment of the globus pallidus), supports the existence of an endogenous cannabinoid system regulating motor activity.
The largest numbers of these neurons were found in portions of the dentate nucleus and the internal segment of the globus pallidus (GPi).
OBJECTIVE: To optimize the accuracy of initial stereotactic targeting for movement disorders surgery, we performed stereotactic localization of the internal segment of the globus pallidus (GPi) and subthalamic nucleus (STN) using magnetic resonance imaging protocols in which the borders of these nuclei were directly visualized.
Thalamic labeling was analyzed following injections of the anterograde tracers, biotinylated dextran amine (BDA) into the internal segment of the globus pallidus (GPi) and wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into the contralateral cerebellar interpositus and dentate nuclei.
A nonlesioning approach by means of deep brain electrodes connected to a programmable neuropacemaker has also been used to inhibit the internal segment of globus pallidus (posteroventral stimulation [ PVS]) reporting comparable clinical efficacy to the one obtained with the ablative method.
D3 binding sites and D3 mRNA positive neurons were most abundant in the limbic striatum and efferent structures, such as the nucleus accumbens, ventral striatum, substantia nigra, internal segment of the globus pallidus, anteroventral nucleus of the thalamus, and rostral pars reticulata of the substantia nigra.
Dual probe microdialysis was employed in intact rat brain to investigate the effect of intrastriatal perfusion with selective dopamine D1 and D2 receptor agonists and with c-fos antisense oligonucleotide on (a) local GABA release in the striatum; (b) the internal segment of the globus pallidus and the substantia nigra pars reticulata, which is the output site of the strionigral GABA pathway; and (c) the external segment of the globus pallidus, which is the output site of the striopallidal GABA pathway.
OBJECTIVE: To evaluate, in a double-blind fashion, the efficacy of deep brain stimulation of the internal segment of the globus pallidus (GPi) contralateral to a previous unilateral medial pallidotomy (MP).
Comparisons within cells in the internal segment of the globus pallidus (Gpi) disclosed that the firing rate was the same at rest, with making a fist, and during movement provoked dystonia.
Pallidotomy, placement of a surgical lesion in the internal segment of the globus pallidus, reduces DID. These findings are consistent with increased inhibitory output from the internal segment of the globus pallidus to thalamus after levodopa administration.
Our experience and a careful review of the literature led to the following choices: 1) selection of Parkinsonian patients with dominant L-Dopa induced dyskinesia, akinetic and rigidity symptoms, 2) use of CT due to the distortion effects of MRI, 3) use of standard (Laitinen) coordinates combined with an image fusion method using MRI, 4) use of stimulation to gauge distance to internal capsule and optic tract, 5) production of vertical lesion covering internal segment of pallidum.
Relative to control conditions, the planning task was associated with an increase in cerebral blood flow centred on the internal segment of the right globus pallidus in the age-matched control subjects, and a decrease in the same region in the patients with Parkinson's disease.
Second, we assume that the output stage of the basal ganglia, the internal segment of the globus pallidus (Gpi), selects a single action from several competing actions via lateral interactions.
The major motor disturbances in Parkinson's disease are thought to be caused by overactivity of the GABAergic internal segment of the globus pallidus (GPi), which acts as a "brake" on the motor thalamus and the cortical motor system to produce the slowness, rigidity, and poverty of movement characteristic of parkinsonian states.
We suggest that arm dystonia in ITD is associated with overactivity of the premotor areas, including the SMA, and that this results from release of the thalamus from the normal inhibitory influence of the globus pallidus internal segment.
The former (central) hypothesis proposes that overactivity of neurons in the internal segment of the globus pallidus inhibits or hyperpolarizes thalamic neurons.
Neither CT nor T1-weighted MR images could detect any changes in the pallidum or subthalamic nuclei, while T2-weighted MR images disclosed bilateral high signals in the pallidum, especially in the internal segment, in all patients.
Firing rates of cells in the internal segment of the globus pallidus (GPi) recorded during this procedure were significantly lower than those observed during pallidotomy for Parkinson's disease, either "on" or "off" medication.
Spontaneous single unit activity of the internal segment of the globus pallidus (GPi) was recorded intraoperatively in the same patients under identical conditions.
Selective stimulation of the DA D1 receptor may provide better integration of neural inputs transmitted to the internal segment of the globus pallidus (referred to as the basal ganglia output) compared with levodopa and selective DA D2 receptor agonist.
Studies of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced parkinsonism in monkeys suggest that excessive inhibitory outflow from the internal segment of the globus pallidus (GPi) suppresses the motor thalamus, which reduces activation of the cerebral cortex motor system, resulting in the slowness and poverty of movement of Parkinson's disease (PD).
In the MPTP-treated monkey HFS buffers STN overactivity and alleviates akinesia and rigidity by reducing inputs to the internal segment of the globus pallidus..
Since a major input to motor thalamus (Voa and Vop) is from the internal segment of the globus pallidus (GPi), neurons with tremor-frequency activity in motor thalamus may receive input from neurons in GPi.
With l-DOPA treatment, the number of D1 receptor numbers was further elevated in caudal putamen (119-123%), dorsal caudate (110-130%), and in the internal segment of the globus pallidus (GPi; 164% of normals) of MPTP-treated monkeys as compared with MPTP treatment alone.
In addition, this view states that striatal output reaches the basal ganglia output nuclei (the substantia nigra pars reticulata (SNR) and the internal segment of the globus pallidus (GPi)) via a 'direct' pathway, and via an 'indirect pathway' which traverses the external segment of the globus pallidus (GPe) and the subthalamic nucleus (STN).
In MPTP-intoxicated monkeys compared with control animals, COI mRNA expression was increased in the subthalamic nucleus (STN) and in the output nuclei of the basal ganglia, i.e., the internal segment of the globus pallidus and the substantia nigra pars reticulata.
Lesions of the internal segment of the globus pallidus are increasingly being utilized in the surgical treatment of advanced Parkinson's disease, yet studies to demonstrate the safety and efficacy of these procedures are only now being completed.
The neostriatum is considered to be involved in the induction of purposeful movements or in the suppression of other movements through the internal segment of the globus pallidus (GP; the entopeduncular nucleus in the rodents) and the substantia nigra (SN) to which the striatal spiny neurons project.
Dopamine depletion in parkinsonian patients causes an increase in neuronal activities in the globus pallidus internal segment and the substantia nigra pars reticulata, resulting in an inhibition of neurons in the thalamus and pedunculopontine nucleus, and developing akinesia and rigidity.
A reversal of the supersensitivity of GABAA receptor in the internal segment of the globus pallidus (-15% on average vs.
All AMPA receptor mRNAs and proteins (GluR1-4) were detected in the internal segment of the globus pallidus (GPi).
To address the question of segregated projections from the internal segment of the globus pallidus (GPi) and the cerebellar nuclei (Cb) to the thalamus in the monkey, we employed a double anterograde labeling strategy combining the anterograde transport of horseradish peroxidase conjugated to wheat germ agglutinin (WGA-HRP) with biotinylated dextran amine (BDA) transport.
the internal segment of the globus pallidus and the substantia nigra pars reticulata, but remained unchanged in the external segment of the globus pallidus and the striatum.
The major motor disturbances in Parkinson's disease are thought to be caused by overactivity of the internal segment of the globus pallidus (GPi), in large part due to excessive drive from the subthalamic nucleus.
In the other case, the hypo-intensity was restricted to the globus pallidus, in which a small area of hyperintensity in its internal segment was demonstrated--the so called 'eye-of-the-tiger' sign.
Parkinson's disease is characterized by an increased excitatory amino acid transmission in the internal segment of the globus pallidus and the substantia nigra pars reticulata. Similarly, injections of CI-977 in the internal segment of globus pallidus (GPi) of the MPTP-treated marmoset alleviated parkinsonian symptoms and allowed the animal to recover its locomotor activity.
MRI showed a discrete lesion in the internal segment of the left globus pallidus.
To examine quantitatively the pathway from the internal segment of the globus pallidus to the primary motor cortex through the thalamus, we compared the distribution of thalamocortical neurons projecting to the motor cortex with the distribution of afferent terminal fields from the pallidum in the ventrolateral nuclear group of the thalamus in four Japanese monkeys by using the anterograde and retrograde double-labeling method. In the same individual monkeys, an anterograde tracer, wheatgerm agglutinin conjugated to horseradish peroxidase, was injected into the internal segment of the globus pallidus after the forelimb part was identified physiologically.
Dyskinesia therefore does not appear to result exclusively from a simple imbalance of activity between the pallidal segments, with hyperactivity in the external and hypoactivity in the internal segment, but also from imbalances within each pallidal segment, possibly with a center-surround organization..
Second, the localizations of retrogradely labelled striatopallidal neurons and of clusters of aggregated striatonigral neurons (as outlined by the transport of 14C-material) were compared in cats that received four horseradish peroxidase-wheat germ agglutinin injections into the internal segment of the globus pallidus and three nigral injections of 14C-amino acids into the substantia nigra pars reticulata. Striatal neurons innervating the internal segment of the globus pallidus were heterogeneously distributed predominantly within the matrix but outside the clusters of aggregated striatonigral neurons.
In all Huntington's disease brains, including grade 1 cases, enkephalin-immunoreactive terminals in the external globus pallidus were significantly reduced compared to substance P-positive boutons in the internal segment of the adjacent section.
Lesser reductions (20-24%) occurred in the substantia nigra and globus pallidus, internal segment.
Efferent signals mediated by the striatal projection neurons are fed to either the internal segment (GPi) or external segment (GPe) of the globus pallidus or substantia nigra pars reticulata (SNr).
This proposal is based on the re-examination of the data on the topographical organization of the frontocortical-basal ganglia connections which indicates that each circuit-engaged striatal region sends divergent projections to parts of both substantia nigra pars reticulata and the internal segment of the globus pallidus (each ventral striatal region sends divergent projections to parts of ventral pallidum, substantia nigra pars reticulata and globus pallidus), and this segregation is maintained at subsequent thalamic and frontocortical levels.
The large neurones outnumber small neurones throughout the pallidum; they abound principally in the external pallidal segment, whereas the small neurones prevail in the internal segment.
In the brains of 3 Japanese monkeys (Macaca fuscata), a combined injection of the tract-tracers Fast Blue (FB), Diamidino Yellow (DY), and horseradish peroxidase-conjugated with wheat germ agglutinin (WGA-HRP) was performed: the retrograde tracers, FB and DY, were injected into a rostral and a caudal sectors of the dorsal part in area 6, and the anterograde tracer, WGA-HRP, was injected into the internal segment of the globus pallidus (GPi).
Many neurons in restricted regions of the dentate nucleus of the cerebellum and in the internal segment of the globus pallidus were labeled by transneuronal transport of virus from area 46.
In the external and internal segments of the pallidum, numerous neurons labeled with the GAD67 cRNA probe were visualized on emulsion radioautographs. In addition, increased GAD67 mRNA levels in the internal segment of the pallidum support the hypothesis of an increased activity of GABAergic neurons in the output structures of the basal ganglia in parkinsonism..
The regulation of GAD65 mRNA levels in the striatum and internal segment of the pallidum suggest an important role for this enzyme in the regulation of GABAergic functions in basal ganglia..
The effects of reversible and irreversible pharmacological manipulations of the neuronal activity in the subthalamic nucleus (STN) on parkinsonian motor signs and neuronal activity in the internal segment of the globus pallidus (GPi) were studied in African green monkeys rendered parkinsonian by treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.
The activity of neurons in the subthalamic nucleus (STN) and in the internal segment of the globus pallidus (GPi) was recorded before (STN, n = 220 cells; GPi, n = 175 cells) and after MPTP treatment (STN, n = 326 cells; GPi, n = 154 cells).
Loss of dopaminergic innervation of the striatum results in overactivity of the glutamatergic pathways from the subthalamic nucleus to the internal segment of the globus pallidus and the substantia nigra pars reticulata, the output nuclei of the basal ganglia. Previous work has shown that local blockade of glutamate receptors in the internal segment of the globus pallidus or substantia nigra pars reticulata leads to marked suppression of parkinsonian signs.
Cholinergic enzyme activities are increased in the internal segment of the globus pallidus (GPi) and into a lesser extent in the external globus pallidus (GPe).
In the basal ganglia, a high density of secretoneurin-like immunoreactivity was found in the internal segment of the globus pallidus, the ventral pallidum and in the pars reticulata of the substantia nigra.
The atrophy was more severe in the external segment (GPe) than in the internal segment (GPi).
In the human basal ganglia, substance P immunoreactivity and mRNA are localized in a subset of spiny striatal neurons that project to the internal segment of the globus pallidus.
2) extrapyramidal system: Moderate to severe degeneration in the substantia nigra, globus pallidus (prominent in the internal segment) and subthalamic nucleus.
Emphasis is placed on the fact that the striatum and the subthalamic nucleus have multiple representations in the two major output structures of the basal ganglia, namely the internal segment of the globus pallidus and the substantia nigra pars reticulata.
Retrograde transneuronal transport of herpes simplex virus type 1 was used to examine the organization of connections in the cebus monkey between an output nucleus of the basal ganglia, the internal segment of the globus pallidus (GPi), and three cortical areas: the primary motor cortex, the supplementary motor ara, and the ventral premotor area.
The external segment of the globus pallidus contained dense collections of NGFr-immunoreactive neurons between 16 and 26 weeks of gestation, whereas the internal segment was devoid of immunoreactive perikarya.
Projections from the cerebellar nuclei (CN) and the internal segment of the globus pallidus (GPi) to areas 6 and 4 via the thalamus were examined electrophysiologically in monkeys.
It was concluded that (a) in parkinsonism, neuronal activities of the caudate nucleus decreased, those of the pars reticulata of the substantia nigra and internal segment of the globus pallidus increased, and those of the ventromedial nucleus of the thalamus depressed markedly; (b) in dyskinesia, periodical discharges of the caudate-putamen complex were the primary event in rodents, resulting in activation of the thalamus; and (c) the caudate nucleus was involved in the manifestation or driving of locomotion, while the putamen was related to regulation of tonus in contralateral muscles with proximal dominancy..
To block glutamatergic excitation, kynurenate (a glutamate antagonist) was locally injected into the putamen and the external segment (GPe) and the internal segment (GPi) of the globus pallidus contralateral to the arm tested.
MRI pallidal abnormalities consisted of decreased signal intensity in T2-weighted images, compatible with iron deposits, and of a small area of hyperintensity in its internal segment ("eye of the tiger" sign).
Recent researches indicate that a subthalamic lesion reduces the excitatory control from the subthalamus to the internal segment of the globus pallidus, which leads to a disinhibition of the thalamus and gives rise to ballism..
This case suggests that excessive output from the subthalamic nucleus to the internal segment of globus pallidus plays a critical role in the pathophysiology of parkinsonian rigidity..
In normal controls, we observed SP-like immunoreactivity in the internal segment of the globus pallidus, where the SP-positive fibers showed typical "woolly fiber" patterns.
Striatal neurons projecting to the external segment of the globus pallidus or the substantia nigra show evident loss, whereas those projecting to the internal segment of the globus pallidus appear relatively spared at presymptomatic and early stages of symptomatic Huntington's disease.
Neuropathological study of one autopsied case disclosed that there were degeneration of spinocerebellar tract, anterior horn cells, pontine nuclei, dentate nucleus, red nucleus, substantia nigra, internal segment of globus pallidus, subthalamic nucleus, and motor nuclei of brain stem; neurons of cerebellar cortex and inferior olivary nucleus were preserved.
Striatal projections to the globus pallidus, through connections with the subthalamic nucleus, modulate excitatory input to the output neurons of the basal ganglia, GABAergic neurons in the internal segment of the globus pallidus and in the substantia nigra, whereas striatal projections directly to these neurons, provide inhibitory inputs.
In each monkey, Fast Blue (FB) was injected into the hand-arm area of the SMA after mapping the somatotopy using intracortical microstimulation, and horseradish peroxidase conjugated with wheat germ agglutinin (WGA-HRP) was injected into the ipsilateral internal segment of the globus pallidus (GPi).
Unilateral injections of the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHA-L) in the internal segment of the pallidum (GPi) of the squirrel monkey (Saimiri sciureus) led to anterograde labeling of fibers ipsilaterally in the following thalamic nuclei: ventral anterior (VA), ventral lateral (VL), centromedian (CM), and lateral habenula (Hbl).
It was concluded that: (1) in parkinsonism, neuronal activities of the caudate nucleus decreased, those of the pars reticulata of the substantia nigra and the internal segment of the globus pallidus increased, and those of the ventromedial nucleus of the thalamus were depressed markedly; (2) in dyskinesia, periodical discharges of the caudate-putamen complex were the primary event in rodents, resulting in activation of the thalamus; and (3) the caudate nucleus was involved in the manifestation or driving of locomotion, while the putamen was related to regulation of tonus in contralateral muscles with proximal dominancy..
In addition, "second-order" neurons were labeled in the deep cerebellar nuclei (dentate and interpositus) and in the globus pallidus (internal segment).
Iontophoretic injections of the fluorescent retrograde tract tracer, Fluoro-gold, into the entopeduncular nucleus of the rat (homologous to the internal segment of the primate globus pallidus) resulted in a substantial number of retrogradely labeled neurons in the ipsilateral globus pallidus (homologous to the external segment of the primate globus pallidus).
The striatum, especially the caudate nucleus, was most frequently and most severely affected, while the internal segment of the globus pallidus was least frequently and least severely affected.
In parkinsonian compared to intact monkeys, the mean spontaneous firing rate of the neurons of the internal segment of the globus pallidus (GPi) increased but that of the prevailing neuronal population in the external segment (GPe) inversely decreased.
In the pallidum, bursting was more prevalent in the external segment and bursts were more intense and more frequent than in the internal segment.
We studied the distribution of striatopallidal projection neurons in 9 adult squirrel monkeys by centering deposits of the retrograde tracer HRP-WGA in either the external segment or the internal segment of the globus pallidus.
Concentrations of gamma-aminobutyric acid (GABA) in the external segment (GPe) and internal segment (GPi) of GP and ST are decreased to 62, 45 and 55% of the control mean, respectively.
For 100 GP neurons [ 41 in the internal segment (GPi) and 59 in the external segment (GPe)], the activity of which changed with task performance, the discharge patterns varied greatly across tasks.
Neurons were further identified as receiving inputs from the cerebellar nuclei or the internal segment of the globus pallidus by excitatory or inhibitory response to stimulation of these nuclei.
Small injections of the lectin Phaseolus vulgaris-leucoagglutinin (PHA-L) in the external segment of the pallidum (GPe) in the squirrel monkey (Saimiri sciureus) and in the rhesus monkey (Macaca mulatta) led to anterograde labeling of fibers in the internal segment of the pallidum (GPi).
In the globus pallidus, firing rate decreased significantly in the internal segment, and both segments showed an increase in discharge variability.
The mean content of iron per internal segment of globus pallidus was greater in schizophrenic patients, but the large variation and small number of patients in our sample may have accounted for the negative findings..
internal segment), body of Luys, substantia nigra, dentate nucleus, red nucleus, cranial and spinal motor nuclei, spinocerebellar tracts and Clarke's column.
All of the putamen neurons identified as projecting to the GP (external and/or internal segment) by an antidromic activation from electrical stimulation of the GP were type II cells.
Injections of the retrograde fluorescent tracer fast blue in the striatum (STR) and nuclear yellow in the internal segment of the globus pallidus (GPi) in the squirrel monkey (Saimiri sciureus) revealed a nigropallidal projection whose cellular origin was largely distinct from that of the nigrostriatal pathway.
The external segment of the pallidum was extremely sparse in D1 binding, whereas the internal segment (or entopeduncular nucleus in the cat) was a site of high D1 binding density. The binding density was greatest in the core of the internal segment, and tyrosine hydroxylase-positive fibers surrounded and weakly dispersed themselves through this core. At the level of the pallidum, such D1 modulation appears to be restricted to the internal segment, which projects to the thalamus, rather than to the external pallidum, which projects to the subthalamic nucleus..
This pathway coursed dorsomedially between the optic tract and the internal segment of the globus pallidus within the ansa peduncularis-ventral amygdalofugal fiber system en route to the substantia innominata-nucleus basalis complex, the bed nucleus of the stria terminalis, the medial preoptic hypothalamic area, the nucleus accumbens and the olfactory tubercle.
Immunoreactivity in the substantia nigra pars reticulata, internal segment of the globus pallidus and ventral pallidum was dense and of a characteristic, "woolly-fiber" morphology.
Stimulation in the ventrolateral internal segment of the globus pallidus (GPi) or in the ansa lenticularis reduced movement times, whereas stimulation at many sites in the external pallidal segment (GPe), dorsal GPi, and putamen increased movement times for the contralateral arm.
Fibers from the medial part of the nucleus accumbens distribute to the ventral pallidum and to the just-mentioned area in the rostral part of the lateral hypothalamus, which most probably represents part of the internal segment of the globus pallidus.
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