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PubMed2003

Changes in GABA(B) receptor mRNA expression in the rodent basal ganglia and thalamus following lesion of the nigrostriatal pathway.

Loss of striatal dopaminergic innervation in Parkinson's disease (PD) is accompanied by widespread alterations in GABAergic activity within the basal ganglia and thalamus. Accompanying changes in GABA(B) receptor binding have been noted in some basal ganglia regions in parkinsonian primates, suggesting that plasticity of this receptor may also occur in PD. However, the molecular mechanisms underlying the changes in receptor binding and the manner and extent to which different GABA(B) receptor mRNA subunits and splice-variants are affected remain unknown. This study used in situ hybridisation to examine the full profile of changes in expression of the known rat GABA(B) receptor genes and gene variants in the basal ganglia and thalamus of rats, brought about by degeneration of the nigrostriatal tract. All of the GABA(B) mRNA species examined showed unique expression patterns throughout the basal ganglia and thalamus. In addition, all exhibited a marked loss of expression (between 46 and 80%) in the substantia nigra pars compacta of animals bearing a complete 6-hydroxydopamine-induced lesion of the nigrostriatal tract, confirming the presence of these variants in dopaminergic neurones in this region. Further analysis of autoradioagrams revealed additional changes only in GABA(B(1a)) mRNA in discrete anatomical regions. Expression of the GABA(B(1a)) variant was significantly increased in the substantia nigra pars reticulata (33+/-2%), entopeduncular nucleus (26+/-1%) and the subthalamic nucleus (16+/-1%). Since these regions all receive reduced GABAergic innervation following nigrostriatal tract lesioning, it is possible that the increased expression occurs as a compensatory measure. In conclusion, these data demonstrate that GABA(B) receptor genes exhibit regional- and subunit/variant-specific plasticity at the molecular level under parkinsonian conditions.

Animals↗

PubMed2004

Basal ganglia activity remains elevated after movement in focal hand dystonia.

Although previous studies of focal hand dystonia have detected cortical sensorimotor abnormalities, little is known about the role of the basal ganglia in this disorder. We report here that when focal hand dystonic patients performed finger-tapping tasks, functional magnetic resonance imaging showed persisting elevations of basal ganglia activity after the tasks ended. We posit that inhibitory control of the basal ganglia may be faulty in focal hand dystonia, and that the increases we observe in "resting" activity may mask basal ganglia abnormalities in standard imaging contrast analyses.

Adult↗

PubMed2006

Oscillations in the basal ganglia under normal conditions and in movement disorders.

A substantial body of work within the last decade has demonstrated that there is a variety of oscillatory phenomena that occur in the basal ganglia and in associated regions of the thalamus and cortex. Most of the earlier studies focused on recordings in rodents and primates. More recently, significant advances have been made in this field of research through the analysis of basal ganglia field potentials recorded from implanted deep brain stimulation electrodes in the basal ganglia of human patients with Parkinson's disease and other disorders. It now appears that oscillatory activity may play a significant role in the pathogenesis of these diseases. The most significant finding is that in Parkinson's disease synchronized oscillatory activity in the 10- to 35-Hz band (often termed "beta-band") is prevalent in the basal ganglia-thalamocortical circuits, and that such activity can be reduced by dopaminergic treatments. The entrainment of large portions of these circuits may disrupt information processing in them and may lead to parkinsonian akinesia (and perhaps tremor). Although less firmly established than the role of oscillations in movement disorders, oscillatory activities at higher frequencies may also be a component of normal basal ganglia physiology.

Animals↗

PubMed2003

Processing emotional tone from speech in Parkinson's disease: a role for the basal ganglia.

In this study, individuals with Parkinson's disease were tested as a model for basal ganglia dysfunction to infer how these structures contribute to the processing of emotional speech tone (emotional prosody). Nondemented individuals with and without Parkinson's disease (n = 21/group) completed neuropsychological tests and tasks that required them to process the meaning of emotional prosody in various ways (discrimination, identification, emotional feature rating). Individuals with basal ganglia disease exhibited abnormally reduced sensitivity to the emotional significance of prosody in a range of contexts, a deficit that could not be attributed to changes in mood, emotional-symbolic processing, or estimated frontal lobe cognitive resource limitations in most conditions. On the basis of these and broader findings in the literature, it is argued that the basal ganglia provide a critical mechanism for reinforcing the behavioral significance of prosodic patterns and other temporal representations derived from cue sequences (Lieberman, 2000), facilitating cortical elaboration of these events.

Affect↗

PubMed2001

Prognostic significance of hyperechogenic lesions in the basal ganglia and thalamus in neonates.

Neonatal cranial ultrasonography at times reveals hyperechogenic lesions in the basal ganglia and thalamus. These lesions have been attributed to a wide variety of pathologic states, among them toxoplasmosis, rubella, cytomegalovirus, and herpes simplex (TORCH) infections, chromosomal abnormalities, and asphyxia. The clinical significance in terms of the neurodevelopmental outcome of this radiologic abnormality is unknown. We performed a developmental evaluation on 16 children aged 2 to 6 years in whom neonatal cranial ultrasonography had demonstrated hyperechogenic lesions in the basal ganglia or thalamus and had no other neurodevelopmental risk factors. There was no significant difference between the average Developmental Quotient of the target population and the normal population in regard to developmental status. We conclude that in our population, an isolated finding of hyperechogenic lesions in the basal ganglia is probably not a predictor of poor neurodevelopmental outcome.

Basal Ganglia↗

PubMed1984

Basal ganglia outputs and motor control.

Several lines of evidence suggest that the role of the basal ganglia in motor control is of a higher order than control of movements per se. First the striatum receives inputs from cortical areas that subserve mnemonic and other cognitive processes. Furthermore, the supplementary motor area (a zone that receives outputs from the globus pallidus via thalamus) exhibits changes in neuronal discharge and metabolic activity during movement planning as well as during movement. It is possible that this activity reflects its pallidal inputs. In addition, cells in another part of the basal ganglia, the pars reticulata of the substantia nigra, exhibit activity that reflects mnemonic as well as oculomotor and visual processes. Finally, there are striatal neurons that respond to stimuli when these stimuli trigger movement but not when responses to the stimuli are extinguished. Taken collectively, these observations are consistent with the view that the basal ganglia may provide an interface between motor centres and cortical areas for higher brain function.

Animals↗

PubMed2008

Bilateral germinoma of the basal ganglia.

Germinoma arising in the bilateral basal ganglia is exceedingly rare, with only five cases reported to date. Owing to non-specific clinical findings and the frequent presence of ill-defined abnormalities without a definite tumor mass on neuroimaging, the diagnosis can be difficult. We describe a case in which magnetic resonance spectroscopy (MRS) findings suggested a tumor and supported the decision to perform biopsy of the lesion.

Adolescent↗

PubMed1980

Monoamines and related enzymes in cerebral cortex and basal ganglia following transient ischemia in gerbils.

The post-ischemic effects on cerebral cortex and basal ganglia monoamine levels and monoamine oxidase (MAO A and B) and catechol-O-methyl transferase (COMT) activities were evaluated in Mongolian gerbils (Meriones unguiculatus) subjected to bilateral common carotid arteries of occlusion for 15 min and reflow for 7 days. Disorders of monoamine metabolism was found in ischemic brain which persisted during the long-term post-ischemia. A rebound increase of norepinephrine and serotonin appeared in early stages (up to 1 h) of post-ischemia both in cerebral cortex and basal ganglia; a rebound increase of dopamine as found only in cerebral cortex. Thereafter, the serotonin level ws enhanced over the control level during the whole post-ischemic period whereas the levels of catecholamines were reduced particularly in basal ganglia. With respect to monoamine content and activities of monoamine degraded enzymes an oscillatory behavior was observed in the post-ischemia. Disorder of the monoamine metabolism found during post-ischemic period possibly contributes to neurological dysfunction after an ischemic insult.

Animals↗

PubMed2006

Relationship between axonal collateralization and neuronal degeneration in basal ganglia.

In this paper we evaluate the hypothesis of a possible link between the degree of axonal collateralization of neurons located within the different components of basal ganglia and the vulnerability of these neurons to neurodegenerative or neurotoxic events. Our results stemmed from single-cell labeling experiments in rodents and primates, immunohistochemical study of the dopaminergic nigrostriatal pathway in parkinsonian monkeys, and immunocytological analysis of the human striatum in normal individuals and in patients with Huntington's disease. Our results indicate that projection neurons within virtually all basal ganglia components are endowed with a widespread and highly collateralized axon that yields a fixed number of terminals. Such a high degree of axonal collateralization allows exquisitely precise interactions between the various basal ganglia nuclei. However, the maintenance of this unique morphological trait implies high-energy consumption and renders basal ganglia neurons highly vulnerable to neurodegenerative, metabolic or neurotoxic insults.

Animals↗

PubMed1994

The basal ganglia and adaptive motor control.

The basal ganglia are neural structures within the motor and cognitive control circuits in the mammalian forebrain and are interconnected with the neocortex by multiple loops. Dysfunction in these parallel loops caused by damage to the striatum results in major defects in voluntary movement, exemplified in Parkinson's disease and Huntington's disease. These parallel loops have a distributed modular architecture resembling local expert architectures of computational learning models. During sensorimotor learning, such distributed networks may be coordinated by widely spaced striatal interneurons that acquire response properties on the basis of experienced reward.

Animals↗

PubMed2006

[Precocious puberty caused by hCG-producing germinoma involving the bilateral basal ganglia and cerebral white matter without 1ypical radiologic findings: case report].

An 8-year-old boy presented with a rare case of germinoma involving the bilateral basal ganglia and cerebral white matter manifesting as precocious puberty. Magnetic resonance (MR) imaging at the initial presentation demonstrated mild hyperintense areas in the bilateral basal ganglia and corpus callosum on T1-weighted images, and a small hyperintense spot in the right internal capsule on T2-weighted images. Human chorionic gonadotropin (hCG) level was elevated in the cerebrospinal fluid (CSF), so we strongly suspected that threre was a hCG-producing germinoma originating in the bilateral basal ganglia. Stereotactic biopsy was performed. Histological examination revealed two-cell pattern germinoma. After three cycles of combination chemotherapy consisting of ifosfamide, cisplatin, and etoposide, followed by whole brain irradiation with a total dose of 24 Gy, the CSF hCG level fell below the detection limit, but MR imaging demonstrated no significant change. Intracranial hCG-producing germinoma should be suspected in patients presenting with precocious puberty and elevated CSF hCG level. Moreover, slight intensity change on MR imaging is important to identify germinoma arising from the basal ganglia in the early stage.

Basal Ganglia Diseases↗

PubMed1985

Local and remote effects of intra-caudate administration of GABA-related drugs on Met-enkephalin release in the basal ganglia.

The possible influence of GABAergic systems on the activity of enkephalinergic neurones within the basal ganglia was examined by measuring the release of Met-enkephalin in the caudate nuclei and pallida of halothane-anesthesized cats treated by intra-caudate applications of GABA-related drugs. Depending on the concentration used, GABA exerted local stimulatory (at 10 microM of the amino acid) or inhibitory (at 0.5 mM) action on Met-enkephalin release in the cat caudate nucleus. Only the inhibition was reproduced by the GABA agonists muscimol (1 microM) and (-)-balcofen(10 microM) and by diazepam 10 microM). Conversely, the intra-caudate application of the GABA antagonist bicuculline enhanced markedly the local release of the pentapeptide. Complementary studies using slices of the rat striatum (caudate nucleus + putamen) revealed that a low concentration of GABA (10 microM) tended to increase the K+-evoked efflux of Met-enkephalin, whereas a high concentration of the amino acid exerted a strong inhibitory effect on the peptide release. Such in vivo and in vitro findings suggest that the GABA-induced inhibition of Met-enkephalin release took place via the stimulation of specific GABA A and GABA B receptors within the caudate nucleus, whereas the GABA-induced increase of the peptide release might involve some intracellular regulatory processes in striatal neurones containing both GABA and enkephalins. In addition to altering the local release of Met-enkephalin, intra-caudate applications of GABA-related drugs affected the peptide release in the ipsilateral globus pallidus and contralateral basal ganglia. The observed changes suggest that GABA A, but not GABA B, receptors participated in some tonic inhibitory influence of striatal GABAergic neurones on the striato-pallidal enkephalinergic system. Furthermore, the present results confirmed previous studies (Bourgoin et al.) showing that GABAergic neurones can contribute to some bilateral modulation of enkephalinergic neurones within the basal ganglia.

Animals↗

PubMed2002

Movement-related changes in synchronization in the human basal ganglia.

There is a wealth of data suggesting that behavioural events are reflected in the basal ganglia through phasic changes in the discharge of individual neurones. Here we investigate whether events are also reflected in momentary changes in the degree of synchronization between neuronal elements. We simultaneously recorded local potentials (LPs) from the subthalamic nucleus (STN) and/or ipsilateral globus pallidus interna (GPi) or scalp EEG during voluntary movements of a hand-held joystick in six awake patients following neurosurgery for Parkinson's disease. Without medication the power within the STN and the coherence between the STN and the GPi were dominated by activity with a frequency of <30 Hz. This coupling was attenuated by movement. In the presence of exogenous dopaminergic stimulation, power within the STN and coherence between the STN and the GPi was dominated by activity at 70-85 Hz, which increased with movement. The movement-related changes in coherence between the STN and EEG showed a similar pattern of pharmacological dependence, as seen subcortically. Movement-related frequency-specific changes in synchronization occur in the basal ganglia and extend to involve subcortico-cortical motor loops. The dynamic organization of activities in the frequency domain might provide a means for temporal co-ordination within and across different processing streams in the basal ganglia. This organization is critically dependent on the level of dopaminergic activity.

Adult↗

PubMed1996

The sensory guidance of movement: a comparison of the cerebellum and basal ganglia.

We used positron emission tomography (PET) to compare the contribution of the cerebellum and basal ganglia to the sensory guidance of movement. In one condition the subjects used a computer mouse to draw a series of lines on a computer screen (DRAW). In the second condition the same lines were presented to the subjects, and they had to track the lines with a mouse pointer on the screen (COPY). In a third condition the subjects were again presented with the same lines, and they simply followed movements of the pointer with their eyes (EYES). In the fourth condition, the subjects fixated a central point, ignoring the sequence of presented lines (FIX). The pons and cerebellum were activated more during visually guided tracking than in freely generated drawing (COPY vs DRAW). The basal ganglia were activated equally in both DRAW and COPY. The prefrontal and inferior temporal cortex were activated more when subjects drew lines freely (DRAW) than when they copied them (COPY). We conclude that the cerebellum is specialized for using sensory information to correct movements, but that the basal ganglia are involved both in movements that are self-generated and in movements that are guided by external cues.

Adult↗

PubMed1998

Physiological aspects of information processing in the basal ganglia of normal and parkinsonian primates.

There are two views as to the character of basal-ganglia processing - processing by segregated parallel circuits or by information sharing. To distinguish between these views, we studied the simultaneous activity of neurons in the output stage of the basal ganglia with cross-correlation techniques. The firing of neurons in the globus pallidus of normal monkeys is almost always uncorrelated. However, after dopamine depletion and induction of parkinsonism by treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), oscillatory activity appeared and the firing of many neurons became correlated. We conclude that the normal dopaminergic system supports segregation of the functional subcircuits of the basal ganglia, and that a breakdown of this independent processing is a hallmark of Parkinson's disease.

Animals↗

PubMed1997

Changes in AMPA glutamate and dopamine D2 receptors in hypoxic-ischemic basal ganglia necrosis.

Changes in the AMPA glutamate receptor subunits (GluR1, 2-3, and 4) and dopamine D2 receptor (D2R) were investigated in 16 cases of hypoxic-ischemic basal ganglia necrosis (BGN) by immunohistochemistry. Immunoreactivity to GluR1, 2-3, and 4 was observed in the cytoplasm and dendrites of small and large neurons in the basal ganglia. Neuronal immunoreactivity to GluR1, 2-3, and 4 was decreased in cases with acute BGN as compared with that in age-matched controls, the areas of decreased immunoreactivity corresponding to the damaged regions observed on hematoxylin and eosin staining. Glia in the basal ganglia exhibited immunoreactivity to GluR4 in 4 patients with acute BGN, 3 of the 4 surviving for 12 to 35 days. In addition, neuronal immunoreactivity to D2R was also decreased in cases of acute BGN, the decrease being similar to that of GluR1, 2-3, and 4. Our results suggest that excitotoxicity mediated by GluR1, 2-3, and 4 is involved in the pathogenesis of hypoxic-ischemic neuronal damage, and that GluR4 expressed in glia of the BG in the late stage of hypoxic-ischemic injury may participate in the delayed and long-term response of the glia to injury. The decrease in neuronal D2R may be related to downregulated synthesis of the D2R protein induced by the decrease in GluR1-4 in the basal ganglia.

Asphyxia Neonatorum↗

PubMed1985

[Results of a study of a family with aggregated occurrence of bilateral symmetrical basal ganglia calcinosis].

We present a familial study (45 members), in which 31 members have been examined. Seven were afflicted with bilateral symmetrical calcification of the basal ganglia (Fahr's syndrome), as verified by CT scans. The case history and biochemical results for one additional proband, who had died, strongly indicate that this patient also had Fahr's syndrome. The wide range of examinations used in our study were aimed at excluding differential diagnoses of bilateral symmetrical calcification of the basal ganglia, other than when the origin was suspected to be in the parathyroid. The examinations had to be undertaken on an outpatient basis. Some of the variables, such as Fe, Cu, and Mg in the plasma, are connected with results that have been published on the composition of the apatite deposits. Psychiatric, psychological, neurological, and EEG examinations are emphasized. Together with the case reports they are meant to illustrate the neuropsychiatric aspects of this syndrome, the composite view of which has often been previously neglected. Nineteen of 31 probands showed neurological, psychopathological, psychological, and encephalographical deviations. We also noted a high incidence of organic brain syndromes that are phenomenologically similar to affective disorders. We believe these deviations to be directly related to morphological alterations of the basal ganglia, possibly due to errors in phosphorous and calcium metabolism. Although the CT scan has greatly facilitated the diagnosis of intracerebral calcifications, we assume that basal ganglia alterations under the CT-density threshold may also be of clinical importance. Our metabolic results, genetic issues, and neuropsychiatric findings are discussed.

Adolescent↗

PubMedDate not supplied

[A general model of the limbic system and basal ganglia: applications to schizophrenia and compulsive behavior of the obsessive type].

The paper presents a model of the behavioural functions and information processing discharged jointly by the limbic system (especially, the hippocampal formation and amygdala) and the basal ganglia (both the dorsal and ventral striatal systems). In general terms, the limbic system plus basal ganglia act as a mechanism for the attainment of goals. The sensory aspects of this overall goal-direction function (recognition of goals and evaluation of the outcomes of action) are dealt with in the limbic system; the motor aspects (establishment and execution of motor programs), in the basal ganglia. The model is applied to an understanding of the neuropsychology of schizophrenia (in particular, positive psychotic symptoms) and obsessive-compulsive disorder. In both cases, emphasis is placed on the interaction between the limbic system and the basal ganglia.

Basal Ganglia↗