PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “BASAL GANGLIA”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources

Role of basal ganglia in limb movements.

Recent anatomic and physiologic studies have shed new light on the functional organization of the basal ganglia and their role in movement. The basal ganglia receive topographically organized input from the entire neocortex. Influences from sensorimotor and "association" cortices appear to remain segregated in the basal ganglia. The concept of segregated parallel subcortical loops subserving "motor" and "complex" functions is discussed. Recent neurophysiologic studies in behaving primates suggest that basal ganglia output plays a role in controlling the direction and amplitude of movement but is not primarily involved in the initiation of limb movement or selection of specific muscles. These studies are generally consistent with data from patients with Parkinson's disease, which likewise indicates a deficit in the programming of movement amplitude in step-tracking tasks, with little or no change in reaction-time or pattern of muscular activity.

Animals↗

Functional properties of AMPA and NMDA receptors expressed in identified types of basal ganglia neurons.

AMPA- and NMDA-type glutamate receptors (AMPARs and NMDARs) mediate excitatory synaptic transmission in the basal ganglia and may contribute to excitotoxic injury. We investigated the functional properties of AMPARs and NMDARs expressed by six main types of basal ganglia neurons in acute rat brain slices (principal neurons and cholinergic interneurons of striatum, GABAergic and dopaminergic neurons of substantia nigra, globus pallidus neurons, and subthalamic nucleus neurons) using fast application of glutamate to nucleated and outside-out membrane patches. AMPARs in different types of basal ganglia neurons were functionally distinct. Those expressed in striatal principal neurons exhibited the slowest gating (desensitization time constant tau = 11.5 msec, 1 mM glutamate, 22 degrees C), whereas those in striatal cholinergic interneurons showed the fastest gating (desensitization time constant tau = 3.6 msec). The lowest Ca2+ permeability of AMPARs was observed in nigral dopaminergic neurons (PCa/PNa = 0.10), whereas the highest Ca2+ permeability was found in subthalamic nucleus neurons (PCa/PNa = 1.17). NMDARs of different types of basal ganglia neurons were less variable in their functional properties; those expressed in nigral dopaminergic neurons exhibited the slowest gating (deactivation time constant of predominant fast component tau1 = 150 msec, 100 microM glutamate), and those of globus pallidus neurons showed the fastest gating (tau1 = 67 msec). The Mg2+ block of NMDARs was similar; the average chord conductance ratio g-60mV/g+40mV was 0.18-0.22 in 100 microM external Mg2+. Hence, AMPARs expressed in different types of basal ganglia neurons are markedly diverse, whereas NMDARs are less variable in functional properties that are relevant for excitatory synaptic transmission and neuronal vulnerability.

Animals↗

Metabotropic glutamate receptor mRNA expression in the basal ganglia of the rat.

Metabotropic glutamate receptors (mGluRs) couple the actions of glutamate to intracellular second messenger systems through G-proteins. The mGluRs play an important role in the regulation of basal ganglia function. Ligand binding studies have revealed that the basal ganglia contain at least two pharmacological types of metabotropic binding sites. Agonists of mGluRs can affect both in vitro electrophysiologic responses of striatal neurons and motor behavior in vivo. Recently, cDNAs encoding five mGluRs have been cloned, each with distinct structural and pharmacological properties. In order to elucidate the function of these receptors in the biology of the extrapyramidal motor system, we have used in situ hybridization to examine the regional and cellular expression patterns of mGluR1-mGluR5 in the adult rat basal ganglia. In the striatum, all of these mGluRs were present in widely varying relative densities and cellular patterns. MGluR5 was particularly prominent, and exhibited a heterogeneous cellular distribution, with labeled and unlabeled populations of neurons. MGluR2 was expressed in a small population of large polygonal striatal neurons. The subthalamic nucleus was the only other basal ganglia structure that expressed mGluR2. Distinct cellular distributions of mGluR expression were also observed within the nucleus accumbens, globus pallidus, ventral pallidum, and substantia nigra pars reticulata. MGluR3 was expressed in glia in all basal ganglia structures, but was observed in neurons only in the striatum, substantia nigra pars reticulata, and very weakly in the subthalamic nucleus. Comparison of the restricted mGluR2 and mGluR3 mRNA distributions with that of metabotropic ligand binding sites supports a possible presynaptic location for these receptors in the basal ganglia. MGluR1 was the only mGluR message prominently expressed in the dopaminergic neurons of the substantia nigra pars compacta, suggesting the involvement of this receptor in the regulation of dopamine release from nigrostriatal terminals.

Animals↗

Dissociating medial temporal and basal ganglia memory systems with a latent learning task.

The medial temporal (MT) lobes and basal ganglia have both been implicated as brain substrates of associative learning. Here, we show a dissociation between medial temporal and basal ganglia damage using a latent learning task, in which prior exposure to cues, uncorrelated with each other, slows subsequent learning of an association between them. Consistent with prior work, we found a robust exposure effect in healthy controls, with exposed controls learning more slowly than non-exposed controls. This effect was abolished in medial temporal amnesia: both exposed and non-exposed amnesic patients learned at the same speed. A group of patients with basal ganglia damage due to Parkinson's disease showed a reversal of the effect: exposed subjects learned faster than non-exposed subjects. Our findings point to distinct and dissociable contributions of medial temporal lobe and basal ganglia structures to learning and memory.

Adult↗

Calcification of the basal ganglia: computerized tomography and clinical correlation.

During a 1-year period, 4219 consecutive computerized tomograms (CT) were reviewed for basal ganglia calcification; 14 patients with such calcification were identified. Calcifications on CT scan were bilateral in 12 of these cases and unilateral in 2. All bilateral calcifications were symmetric. The globus pallidus was the site of calcification in 13 of the 14 patients. Bilateral dentate nucleus calcification was seen in one patient. Skull radiograms were normal in all but one. Patients had diverse symptoms that were often explained by other findings, suggesting that calcifications may be coincidental and that basal ganglia calcification may not be a nosologic entity. Disturbances of calcium metabolism were not found in these patients, minimizing the pathophysiologic significance of altered calcium metabolism and the need for extensive endocrinologic evaluation. The finding of basal ganglia calcification alone does not justify invasive diagnostic procedures. Extrapyramidal signs may be associated with basal ganglia calcification; parkinsonism associated with basal ganglia calcification differs from idiopathic parkinsonism in being resistant to levodopa therapy.

Adult↗

Bright basal ganglia in T1-weighted magnetic resonance images are frequent in patients with portal vein thrombosis without liver cirrhosis and not suggestive of hepatic encephalopathy.

BACKGROUND/AIMS: Deposition of paramagnetic substances in basal ganglia, resulting in increased signals in T1-weighted magnetic resonance images (bright basal ganglia), is frequently seen in liver cirrhosis. The present study describes the prevalence of bright basal ganglia and its clinical significance in patients with long-standing portal vein thrombosis in the absence of liver cirrhosis. METHODS: Six patients with angiographically proven complete portal vein thrombosis and cavernomatous transformation without signs of acute or chronic liver disease were studied by magnetic resonance imaging of the brain, neuropsychiatric evaluation, psychometric tests, electroencephalography, and determination of arterial ammonia levels and of serum manganese concentrations from peripheral venous blood. RESULTS: Five out of six patients demonstrated increased signal intensity in the basal ganglia. Overt portal-systemic encephalopathy was not noted prior to or at the time of evaluation. Normal EEG results were recorded in all patients. Only one of the six patients had pathological results in at least two out of four psychometric tests. This latter patient had had a large right-sided brain infarction. Arterial ammonia concentrations were normal in four of the six patients; one patient with increased ammonia levels had concomitant renal insufficiency with azotemia. The other four patients had no relevant concomitant diseases. Serum manganese levels were non-significantly increased compared with a control group (p=0.06), but they were significantly correlated to basal ganglia signal intensity (R=0.88; p=0.02). CONCLUSIONS: Our results demonstrate that bright basal ganglia primarily represent shunt-induced alterations. They are not directly associated with disturbed liver function nor with portal-systemic encephalopathy.

Adult↗

[A case of bilateral necrosis of the basal ganglia after hypotensive shocks].

We reported a case with bilateral necrosis of the basal ganglia after hypotensive shocks. The patient was a 69-year-old woman, who fell into a hypotensive shock (B.P. below 40 mmHg) of unknown origin during examination of her bladder cancer and was admitted into CCU. After admission, hypotensive shocks were repeated four times (B.P. below 50 mmHg each time). Neurological examination revealed a left spastic hemiplegia. Brain CT on 10th day showed bilaterally low density areas around the basal ganglia and a diagnosis of brain infarction was made. She gradually presented quadriplegia and symptomatic changes from pyramidal to extrapyramidal signs. Brain CT on 24th day showed bilateral hemorrhagic infarction of the basal ganglia with enhanced effect. On 79th day, she again fell into shock and died. Neuropathological examination of the brain was as follows. 1) laminar necrosis of the deep layers of the cerebral cortex, 2) bilateral necrosis of the hippocampal Sommer sector, 3) bilateral necrosis of the caudate nucleus, putamen and pallidum with neuronal loss and infiltration of fat granule cells, 4) sparing of the internal capsules, 5) bilateral necrosis of the reticular zone of the substantia nigra, 6) foci of fresh necrosis and loss of Purkinje cells in the cerebellum. These lesions are consistent with those of selective vulnerability in hypoxia as described by Scholz et al. An extensive distribution of cerebral as well as basal ganglia necrosis in this case was caused by repeated shocks.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Cerebrovascular changes in the basal ganglia with HIV dementia.

BACKGROUND: HIV dementia is a form of subcortical dementia. Clinical, radiologic, pathologic, and biochemical studies suggest a major contribution of basal ganglia dysfunction to the pathogenesis of this disorder. Many investigators have proposed a contribution of a disrupted blood-brain barrier (BBB) to the pathogenesis of HIV dementia. OBJECTIVE: To identify microvascular abnormalities in vivo in basal ganglia or white matter of persons with HIV dementia. METHODS: Time course of MRI postcontrast enhancement was determined in basal ganglia and white matter of HIV-infected persons without dementia (Memorial Sloan Kettering [MSK] score of 0; n = 4); HIV-infected persons with mild dementia (MSK score of 0.5; n = 2); and HIV-infected persons with moderate-to-severe dementia (MSK > or = 1.0; n = 6). RESULTS: Increased basal ganglia enhancement was observed in individuals with moderate-to-severe dementia relative to nondemented individuals, both immediately and 30 minutes after contrast administration. Decline of basal ganglia enhancement was slower in the moderately to severely demented patients and, when normalized to intravascular enhancement of sagittal sinus, suggested leakage of contrast agent, consistent with increased permeability of BBB. A significant correlation between the postcontrast fractional enhancement at 30 minutes (FE30) and the MSK score was noted. White matter showed no significant differences in postcontrast enhancement among the three groups. CONCLUSION: Increased early enhancement in basal ganglia of the HIV dementia group is consistent with increased regional cerebral blood volume (rCBV). Increased late enhancement is strongly suggestive of BBB disruption. Similar abnormalities were absent in the white matter adjacent to the caudate nucleus.

AIDS Dementia Complex↗

Dopaminergic dysbalance in distinct basal ganglia neurocircuits: implications for the pathophysiology of Parkinson's disease, schizophrenia and attention deficit hyperactivity disorder.

The basal ganglia form a forebrain system that collects signals from a large part of the neocortex, redistributes these cortical inputs both with respect to one another and with respect to inputs from the limbic system, and then focuses the inputs of this redistributed, integrated signals into particular regions of the frontal lobes and brainstem involved in aspects of motor planning and motor memory. Movement disorders associated with basal ganglia dysfunction comprise a spectrum of abnormalities that range from the hypokinetic disorder (from which Parkinson's disease, PD, is the best-known-example) at one extreme to the hyperkinetic disorder (exemplified by Huntington's disease and hemiballism) at the other. In addition to disorders of movement, major mental disorders including schizophrenic-like states and attention deficit hyperactivity disorder (ADHD) have been linked to abnormalities in the basal ganglia and their allied nuclei. In this paper we discuss recent evidence indicating that a dopamine-induced dysbalance of basal ganglia neurocircuitries may be an important pathophysiological component in PD, schizophrenia and ADHD. According to our model, the deprivation of dopaminergic nigro-striatal input, as in PD, reduces the positive feedback via the direct system, and increases the negative feedback via the indirect system. The critical consequences are an overactivity of the basal ganglia output sites with the resulting inhibition of thalamo-cortical drive. In schizophrenia the serious cognitive deficits might be partly a result of a hyperactivity of the inhibitory dopamine D(2) transmission system. Through this dysinhibition, the thalamus exhibits hyperactivity that overstimulates the cortex resulting in dysfunctions of perception, attention, stimulus distinction, information processing and affective regulation (inducing hallucinations and delusions) and motor disabilities. Recent studies have strongly suggested that a disturbance of the dopaminergic system is also involved in the pathophysiology of ADHD. The most convincing evidence comes from the demonstration of the efficacy of psychostimulants such as the dopamine transporter (DAT) blocker methylphenidate in the symptomatic treatment of ADHD. Genetic studies have shown an association between ADHD and genes involved in dopaminergic neurotransmission (for example the dopamine receptor genes DRD4 and DRD5, and the DAT gene DAT1). DAT knockout mice display a phenotype with increased locomotor activity, which is normalized by psychostimulant treatment. Finally, imaging studies demonstrated an increased density of DAT in the striatum of ADHD patients. Which system is disturbed and whether this system is hyper- or hypoactive is not unambiguously known yet.

Antipsychotic Agents↗

Providing explicit information disrupts implicit motor learning after basal ganglia stroke.

Despite their purported neuroanatomic and functional isolation, empirical evidence suggests that sometimes conscious explicit processes can influence implicit motor skill learning. Our goal was to determine if the provision of explicit information affected implicit motor-sequence learning after damage to the basal ganglia. Individuals with stroke affecting the basal ganglia (BG) and healthy controls (HC) practiced a continuous implicit motor-sequencing task; half were provided with explicit information (EI) and half were not (No-EI). The focus of brain damage for both BG groups was in the putamen. All of the EI participants were at least explicitly aware of the repeating sequence. Across three days of practice, explicit information had a differential effect on the groups. Explicit information disrupted acquisition performance in participants with basal ganglia stroke but not healthy controls. By retention (day 4), a dissociation was apparent--explicit information hindered implicit learning in participants with basal ganglia lesions but aided healthy controls. It appears that after basal ganglia stroke explicit information is less helpful in the development of the motor plan than is discovering a motor solution using the implicit system alone. This may be due to the increased demand placed on working memory by explicit information. Thus, basal ganglia integrity may be a crucial factor in determining the efficacy of explicit information for implicit motor-sequence learning.

Adult↗

Basal expression of c-Fos and Zif268 in the rat basal ganglia: immunohistochemical characterization of striatal Zif268-positive neurons.

Basal expression of the protein products of the inducible immediate early genes (IEGs), c-Fos and Zif268, was investigated in five regions of the rat basal ganglia using immunohistochemistry. In particular, high basal levels of Zif268 but very low levels of c-Fos were seen in the caudate-putamen (CPu). Double immunostaining revealed that many of the constitutively expressed Zif268-positive neurons were GABAergic but very few were cholinergic or neuronal nitric oxide synthase (nNOS)-positive, and some of the Zif268-positive neurons were also immunopositive for a glutamate NMDA receptor subunit NR1 or NR2A. No regional difference between the medial and lateral parts of the CPu was observed in the cellular phenotypes of Zif268-positive neurons. Almost no basal levels of Zif268 were seen in the other four regions: the globus pallidus, entopeduncular nucleus, subthalamic nucleus and substantia nigra pars reticulata. As in the CPu, negligible levels of c-Fos were seen in these four regions. Differential expression of these two IEGs may suggest gene-specific and region-specific functions of c-Fos and Zif268 in the basal ganglia. Constitutive expression of Zif268 existing mainly in the GABAergic neurons in the CPu may at least in part be maintained by glutamatergic afferents.

Animals↗

Arm movement performance during reversible basal ganglia lesions in the monkey.

Arm motor performance of eight Cebus monkeys was examined during reversible cooling in the ventral lateral region of the putamen and globus pallidus (primarily the external segment), where neurons discharging during arm movements have been found (DeLong 1972). When attempting to hold a handle stationary during basal ganglia cooling, all monkeys developed flexion at the wrist and some developed a slow flexion drift of the arm at the elbow. The prominence of wrist flexion emphasizes that the basal ganglia may normally influence distal musculature. During basal ganglia cooling an increase in segmental stretch reflexes (15-30 ms) was sometimes observed following arm perturbations, but no consistent increase occurred in the later EMG responses (30-95 ms) in contrast to results obtained in Parkinsonian patients (Tatton and Lee 1975). No major changes were observed in the time of onset of the earliest EMG activity in the agonist muscle in a simple reaction time elbow movement task during basal ganglia cooling. Basal ganglia lesions produced major disorders in both flexion and extension movements including slowing of movements and rebound of the arm towards its initial position after onset of movement. These disorders were accompanied by an increase in tonic activity of both flexors and extensors while holding and by increased levels of cocontraction of agonists and antagonists during attempted movements. It is suggested that this basal ganglia disorder is due to a failure to achieve the correct balance of activity between agonists and antagonists that is appropriate for a particular motor act.

Animals↗

[CT and MR imaging of germinomas arising in basal ganglia and thalamus].

OBJECTIVE: To evaluate the role of CT and MR imaging in diagnosing germinomas arising in the basal ganglia and thalamus. METHODS: MR imaging of 11 boys (ranging in age from 3-15 years with a median of 10.7 years) with germinomas arising from the basal ganglia and thalamus was reviewed retrospectively and the imaging findings were compared with the features of 86 germinomas in other regions. The tumors located at basal ganglia in 9 and at thalamus in 2. All diagnosis was proved operatively and pathologyically. Five cases were studied using both CT and MR, 4 were examined with MR and 2 with CT only. RESULTS: In this series of 11 tumors, 9 were located in the basal ganglia and 2 in the thalamus. The shape of six tumors was global and 5 was lobulated. The cystic components or necrosis were intratumoral in 5 patients and hemorrhage in 4. Patchy enhancement was found in 9 patients and ring-enhancing lesions in 2. Tumor spread oppositely in 4 patients. Five patients demonstrated cortical atrophy ipsilaterally. CONCLUSION: The germinomas arising from the basal ganglia and thalamus have sex, location and imaging characteristics. Therefore, it is possible to make preoperative diagnosis using CT or MR.

Adolescent↗

Microsurgical removal of arteriovenous malformations of the basal ganglia.

Arteriovenous malformations in the basal ganglia region have been a problem in neurosurgical practice. We report six cases of deep-seated malformations fed mainly by the perforating branches of the middle cerebral artery. There were no deaths in the series. Four patients returned to their previous activities, and the other two patients had persistent hemiparesis and dysphasia, present preoperatively, with worsening in one case. Both of these patients improved and are independent. We show the feasibility of satisfactory microsurgical treatment of these lesions based on the knowledge of microanatomical studies.

Basal Ganglia↗

Parkinson's disease: a major hypokinetic basal ganglia disorder.

Disorders of the basal ganglia can be broadly divided into two: ones that manifest hypokinesia or those that elicit hyperkinesia. Parkinson's disease is the commonest form of hypokinetic disorder. The term Parkinson's disease (PD) usually encompasses idiopathic and Parkinsonian-like syndromes. PD is a chronic and progressive disease, in which the symptoms tend to appear unilateral to begin with. Subsequently subtle dysfunctions on the contralateral side may also be observed. Tremor, akinesia and rigidity are some of the classical features of the disease. Although many hypotheses have been proposed, the cause of PD largely remains obscure. Management of PD includes pharmacological treatment or/and surgical intervention.

Animals↗

Number processing and basal ganglia dysfunction: a single case study.

Numerical processing has never been investigated in a case of Fahr's disease (FD) and only rarely in cases of basal ganglia dysfunction. The study describes the cognitive decline of a pre-morbidly high-functioning patient (medical doctor) affected by FD and his difficulties in number processing. A MRI scan revealed bilateral calcifications in the basal ganglia and a brain PET showed a massive reduction of glucose metabolism in the basal ganglia and both frontal lobes, but no other brain abnormalities. The patient's cognitive deficits included impairments in problem solving, in cognitive set shifting and in mental flexibility, as well as in verbal memory. These deficits are attributed to the disruption of the dorsolateral prefrontal circuit involving the basal ganglia. In number processing, the patient showed a severe deficit in the retrieval of multiplication facts, deficits in all tasks of numerical problem solving and in the execution of complex procedures. Importantly, he also showed a dense deficit in conceptual knowledge, which concerned all test conditions and all operations. The findings confirm the predictions of the triple code model in so far, as a disruption of cortico-subcortical loops involving the basal-ganglia may lead to specific deficits in fact retrieval. However, no verbal deficit, as assumed in the triple code model and reported in similar cases, could be observed. The present findings further add to current knowledge on numerical processing, showing how fronto-executive dysfunction may disrupt conceptual understanding of arithmetic. This study shows that not only parietal lesions may lead to severe deficits in conceptual understanding, but that basal ganglia lesions leading to frontal dysfunction may have a devastating effect.

Basal Ganglia Diseases↗

Identification of a locus on chromosome 14q for idiopathic basal ganglia calcification (Fahr disease).

Idiopathic basal ganglia calcification (IBGC) is a neurodegenerative syndrome that is associated with a variety of movement disorders and neurobehavioral and cognitive manifestations. Despite numerous clinical, pathological, and biochemical investigations, its etiology remains unknown. We have identified a multigenerational family with dominantly inherited IBGC and, in 24 members of this family, performed a whole-genome scan using polymorphic microsatellite markers to identify the first chromosomal locus for this disorder (IBGC1). A maximum two-point LOD score of 3.37 was obtained at marker D14S1014, and a maximum multipoint LOD score of 4.95 was obtained between D14S75 and D14S306. The minimal haplotype shared by affected patients extended over a 17.1-cM region bounded by D14S70 and D14S66, which is potentially further narrowed to a 13.3-cM region by a recombination observed in a patient with probable affected status. The age at onset appeared to be decreasing by an average of >20 years with each transmission, which is consistent with genetic anticipation.

Adolescent↗

Behavior and the basal ganglia.

When viewed as a whole, these basal ganglia-thalamo-cortical circuits appear to play a modulating role in a wide range of behaviors. At the cortical level, given convergence upon specified regions within the frontal lobes, the behaviors in question would be those dependent upon SMA, premotor, frontal eye fields, dorsolateral, and orbitofrontal outflow targets. Broadly speaking, processes such as the generation, maintenance, switching, and blending of motor, mental, or emotional sets would be involved. Accordingly, in basal ganglia disease, the planning and the execution of the above behavioral domains can be affected. Given the diversity and complexity of activity within the basal ganglia, the consequences of disruption depend largely upon lesion site and the associated interplay of neurochemical factors. For example, in the motor domain, damage to various striatal circuitry levels can result in either hypo- or hyperkinetic disorders of movement. Following this analogy, it might also be said that diverse lesions, depending on site, can result in problems with the development and maintenance of behavioral sets ("hypophrenic") versus problems in relinquishing preferential sets ("hyperphrenic"). These contrasting patterns are best represented in PD and OCD, respectively. In the latter case, however, the "hyperphrenic" pattern would only apply to those behaviors which are part of the obsessional rituals. This suggests that procedural system "overdrive" remains domain-specific as is the case for most operations within the procedural system. To return to the broad principle of habituation, a process first described in the context of the visual system and its connections with the tail of the caudate nucleus, it would be tempting to view PD and OCD as disorders of "under" and "over" habituation to behavioral routines. Unfortunately, the situation has proven to be more complex in view of recent neuropsychological findings (Nicholson et al., in preparation). Using a variety of problem-solving and other cognitive tasks, both PD and OCD patients were found to require more practice and/or the provision of external guidelines to facilitate habit formation. Thus, in both cases, as in other disorders of the basal ganglia, the establishment of useful heuristics by which to direct adaptive behavior suffers. OCD patients therefore appear to have at least two compartmentalized types of basal ganglia dysfunction: the ritualistic compulsions and obsessions as well as the heuristic inefficiency (i.e., poor procedural mobilization). PD patients would also suffer a similar fate as it is known that the degrees of motor versus nonmotor (i.e., procedural) deficit are poorly correlated (42).(ABSTRACT TRUNCATED AT 400 WORDS)

Affect↗