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PubMed2000

Linear hyperechogenicity within the basal ganglia and thalamus of preterm infants.

Linear hyperechogenicity (LHE) within the basal ganglia and thalamus is an uncommon sonographic finding in preterm infants and is of unclear significance. The study objectives were to determine the clinical characteristics and neurodevelopmental outcome in preterm infants who develop LHE. Ten preterm and 20 control infants were evaluated developmentally at 18 months adjusted age using the Bayley Scales of Infant Development. LHE was diagnosed at 4 weeks (range = 1-11). Antenatal glucocorticoid therapy was more common in infants with LHE than in the control infants (90% vs 45%). Four (44%) of nine LHE infants and no control infants were positive for cytomegalovirus (P = 0.02, and three of 10 LHE infants and no control infants had a hypothyroid (P = 0.03). The mental development scores and behavioral evaluation results were lower in the infants with LHE than in the control infants (73.7 +/- 9.7 vs 83.7 +/- 9.4, P = 0.01 and 23.7 +/- 20.1 vs 43.9 +/- 25.4, P = 0.04, respectively). The infants without LHE also had poorer motor quality (22.8 +/- 20. 5 vs 55.7 +/- 37.4, P = 0.02) and lower emotional regulation scores (25.7 +/- 16 vs 42.3 +/- 24, P = 0.06) than the control infants. Preterm infants with LHE are at an increased risk of adverse neurodevelopmental outcome and, in particular, cognitive and behavioral performance. The sonographic evolution of LHE may be a marker of a diffuse insult to the brain.

Basal Ganglia↗
PubMed2001

Effect of MPTP-induced denervation on basal ganglia GABA(B) receptors: correlation with dopamine concentrations and dopamine transporter.

We investigated the effect of MPTP-induced lesion of the substantia nigra pars compacta (SNpc) dopaminergic neurons on GABA(B) receptors in the basal ganglia of mice and monkeys using receptor autoradiography and in situ hybridization. The extent of the lesion was measured with striatal catecholamine content, striatal binding of (125)I-RTI-121 to dopamine transporter (DAT), and DAT expression in the SNpc. GABA(B) receptors in mice brain were evaluated using (3)H-CGP54626 and its expression was measured with oligonucleotides probes targeting the mRNAs of GABA(B(1a+b)), GABA(B(1a)), GABA(B(1b)), GABA(B(2)) subunits. In monkeys, (125)I-CGP64213 and selective probes for GABA(B(1a+b)) and GABA(B(2)) mRNAs were used. In mice, dopamine content, (125)I-RTI-121 binding, and DAT expression were reduced by 44%, 40%, and 39% after a dose of 40 mg/kg of MPTP and 74%, 70%, and 34% after 120 mg/kg of MPTP, respectively. In monkeys, dopamine content and DAT expression were decreased by more than 90% and 80%, respectively. In the striatum and the subthalamic nucleus, GABA(B) receptors were unchanged following MPTP in both species. In the SNpc of mice, MPTP (120 mg/kg) induced a significant decrease of (3)H-CGP54626 binding (-10%) and of the expression of GABA(B(1a+b)) mRNA (-13%). The decrease of the expression of GABA(B(1a+b)) mRNA was correlated with dopamine content, (125)I-RTI-121 binding and DAT expression. In MPTP-treated monkeys, (125)I-CGP64213 binding (-40%), GABA(B(1a+b)) mRNA (-69%) and GABA(B(2)) mRNA (-66%) were also significantly decreased in the SNpc. Our results suggest that MPTP-induced denervation is associated with a decrease of GABA(B) receptors restricted to the SNpc. These observations may be relevant to the pathophysiology of motor disorders involving dysfunction of the basal ganglia such as Parkinson disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1998

The postnatal development of AMPA receptor subunits in the basal ganglia of the rat.

In situ hybridization and immunohistochemistry were used to characterize the expression pattern of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors during postnatal development in the rat basal ganglia. All subunit transcripts showed some degree of developmental regulation. GluR1 and GluR2 are expressed at high levels in the neonate with reduced expression in the adult. GluR3 and GluR4 are expressed at significantly lower levels in both neonates and adults and have much more modest degrees of reduced expression in adults as compared with GluR1 and GluR2. Analysis of the flip and flop transcript isoforms indicates that GluR1 flip and flop and GluR2 flip are the predominately expressed splice variants in adults. Observed changes in the expression of the AMPA receptor transcripts indicate that there are fundamental differences in the expression of these receptor subunits in adults and neonates. This phenomenon may play a significant role in the establishment of proper synaptic circuitry within the developing basal ganglia in early postnatal life as well as contributing to differences in susceptibility to injury and disease in the aging brain.

Animals↗
PubMed1992

Hyperechoic lesions in the basal ganglia: an incidental sonographic finding in neonates and infants.

Cerebral ultrasound (US) imaging was performed as a screening procedure in approximately 3,600 neonates and infants over a period of 18 months. Hyperechoic lesions in the basal ganglia and thalamic region were detected incidentally in 15 of these patients. Clinical diagnoses included cytomegalovirus infection, asphyxia, rotavirus infection, prematurity, amniotic infection, dysmorphic stigmata, hyperbilirubinemia, congenital heart disease, and diabetic fetopathia. Lesions showed a single punctate (n = 5), multiple punctate (n = 8), or stripe-like pattern (n = 2), with no disease-specific distribution. Computed tomography performed in two of the 15 patients was normal. Lesions resolved within four to seven months in four of eleven cases who had follow-up studies, whereas echogenicities persisted in the remaining seven patients over a period of observation ranging between one to 15 months. Our results indicate that hyperechoic lesions in the basal ganglia and thalamic region may be associated with congenital infections and asphyxia, but could indicate some other unknown pathology. No correlation was found between the morphology of foci and both clinical diagnosis and results of follow-up studies.

Basal Ganglia Diseases↗
PubMed1999

The basal ganglia: a vertebrate solution to the selection problem?

A selection problem arises whenever two or more competing systems seek simultaneous access to a restricted resource. Consideration of several selection architectures suggests there are significant advantages for systems which incorporate a central switching mechanism. We propose that the vertebrate basal ganglia have evolved as a centralized selection device, specialized to resolve conflicts over access to limited motor and cognitive resources. Analysis of basal ganglia functional architecture and its position within a wider anatomical framework suggests it can satisfy many of the requirements expected of an efficient selection mechanism.

Animals↗
PubMed2003

The effect of 6-hydroxydopamine lesions on the release of amino acids in the direct and indirect pathways of the basal ganglia: a dual microdialysis probe analysis.

The loss of dopaminergic neurons of the substantia nigra in Parkinson's disease and in animal models of Parkinson's disease is associated with an imbalance in the activity of the so-called 'direct' and 'indirect' pathways of information flow through the basal ganglia. The aim of the present study was to determine whether the imbalance is reflected in changes in the release of GABA, aspartate and glutamate in the pathways using dual probe microdialysis in freely moving rats. Control and 6-hydroxydopamine-(6-OHDA)-lesioned rats were implanted with microdialysis probes in the neostriatum and substantia nigra or globus pallidus and the release of amino acids was analysed in the dialysates. Basal levels of amino acids were largely unaltered by the 6-OHDA lesion; however, the levels of GABA in the globus pallidus dialysates were significantly elevated in the lesioned rats, indicating an imbalance in favour of the indirect pathway. Administration of kainic acid to the neostriatum enhanced the release of GABA locally and in the distal probes in the substantia nigra and globus pallidus. In 6-OHDA-lesioned rats, stimulated release of GABA in the substantia nigra was abolished, indicating a reduction in transmission along the direct pathway. Thus, consistent with the direct-indirect pathway model of the basal ganglia, the 6-OHDA lesion results in an elevation of the basal release of GABA in the striatopallidal (indirect) pathway and a reduction in the evoked release of GABA in the striatonigral (direct) pathway. These imbalances may underlie, at least in part, the motor abnormalities of Parkinson's disease and in animal models of Parkinson's disease.

Adrenergic Agents↗
PubMed2003

Olfactory dysfunction in hereditary ataxia and basal ganglia disorders.

In the present study the olfactory system of hereditary ataxia patients was tested using the smell identification test. Two previous findings suggested a possible olfactory impairment in these patients. First, an olfactory dysfunction has been found in different neurodegenerative diseases, and second, human functional imaging has shown cerebellar activation during olfaction. As an initial approach to determine if cerebellar ataxia impairs the olfactory process, cerebellar ataxia patients, along with basal ganglia patients, were tested. The results show an olfactory deficit in both basal ganglia and hereditary ataxia patients. Further exploration of the olfactory capacities in hereditary ataxia is necessary to elucidate the specific nature of the deficits.

Adult↗
PubMed1999

Light deprivation soon after frontal brain trauma accelerates recovery from attentional deficits and promotes functional normalization of basal ganglia.

BACKGROUND: Light deprivation significantly accelerates recovery from attention deficits (neglect) after cortical ablation in rats. We hypothesized that light deprivation would improve recovery after traumatic contusive brain injury (TBI) and do so by enhancing dopaminergic function in the ipsilateral basal ganglia. METHODS: Adult rats received left frontal contusion injury and were placed into darkness or standard light/dark cycling for 48 hours. Neurologic evaluation included attentional and sensorimotor tasks. Amphetamine-induced production of the immediate early gene protein product Fos was quantified to determine neuronal dopaminergic response in caudate-putamen (striatum). RESULTS: Unilateral frontal TBI produced severe contralateral deficits in all tasks. Postoperative light deprivation resulted in improved recovery from attentional but not sensorimotor deficits. Five days after injury, ipsilateral striatal Fos expression was reduced by 51% in TBI rats experiencing normal light cycling (p < 0.006). In contrast, postoperative light deprivation normalized striatal Fos expression. By 6 weeks, all TBI rats demonstrated nearly full recovery and striatal Fos expression was symmetrical between the two striata. CONCLUSION: Postoperative light deprivation may improve recovery from TBI-induced attention deficits by normalizing basal ganglia function.

Amphetamine↗
PubMed1999

Basal ganglia calcification induced by excitotoxicity: an experimental model characterised by electron microscopy and X-ray microanalysis.

Activation of glutamate receptors induces an excitotoxic neurodegenerative process characterised in some brain areas by the formation of calcium precipitates. To examine the pathogenesis of basal ganglia calcification (BGC), an improved procedure of X-ray microanalysis was used to study experimental excitotoxic calcification in the rat. Three weeks after injection of ibotenic acid (IBO) in the rat basal forebrain, calcified inclusions within hypertrophied astrocytes were characterised. They appeared to form part of a filamentous structure localised in the cytoplasm in association with normal mitochondria and other organelles. Larger inclusions were surrounded by reactive microglia. The main inorganic components in these deposits were Ca and P, frequently accompanied by S. Al, Si and K. The shape and Ca/P molar ratio of the large deposits (>10 microm) indicate that they may be biological apatites. Aluminosilicates were detected as small deposits (<4 microm) free of other mineral constituents. To our knowledge this is the first report showing that IBO lesion induces brain accumulation of aluminosilicates similar to that described in Alzheimer's or Fahr's patients. Our data indicate that precipitation of Ca and Al may reduce their IBO-induced increased concentration. In conclusion, the experimental model and the improved efficiency of X-ray analysis described may help us to understand the pathogenesis of BGC.

Aluminum Silicates↗
PubMed2003

Hypointensity in T2-weighted images of the basal ganglia in solvent-exposed patients with multiple sclerosis: clinical, MRI and CSF characteristics.

Several studies have indicated an association between MS and organic solvent exposure. Our objective was to analyse differences regarding cerebrospinal fluid (CSF) properties, magnetic resonance imaging (MRI) features and cerebral metabolites, measured by proton spectroscopy (1H-MRS), in 20 patients with spontaneous multiple sclerosis (MS) and in 20 patients with MS after solvent exposure; 15 healthy subjects served as controls. CSF examinations were retrospectively reviewed from the medical files. There were no significant differences in the CSF regarding pleocytosis, spinal-serum albumin ratio or mean extended IgG index. However, T2-weighted images of the solvent-exposed MS patients showed more hypointenseareas in the basal ganglia. Hypointensity on T2-weighted images of the basal ganglia in the solvent-exposed MS patients may correspond to neurodegeneration and could be an early event in MS.

Adult↗
PubMedDate not supplied

Functional details of the basal ganglia as related to the spatial organization of their fibers in cortex and thalamus.

This study compared the results of experimental-morphological and physiological studies in which facts were obtained regarding the functional and morphological heterogeneity of the basal ganglia. Experiments were done on dogs in order to study delayed responses and Hunterian delayed choice responses. Electrical and chemical stimulation of striopallidal structures and recording of spike activity in neurons were done in cats during the formation of conditioned reflexes. Morphological studies were done on cats and dogs by the technique of axon-terminal degeneration. On the basis of an analysis of our own data and data in the literature we have advanced the hypothesis that: 1)There is a correlation between the general features of the disturbance in higher nervous activity and the overlap of striopallidal projections onto cortical and thalamic structures; 2) in a series of cases the behavioral disturbance after shut-off or stimulation of the thalamic structures; 2) in a series of cases the behavioral disturbance after shut-off or stimulation of the basal ganglia can be correlated with the topical details of their projection onto cortical fields and thalamic nuclei.

Animals↗
PubMed2002

Multisecond periodicities in basal ganglia firing rates correlate with theta bursts in transcortical and hippocampal EEG.

Multisecond oscillations in firing rate with periods in the range of 2-60 s (mean, 20-35 s) are present in 50-90% of spike trains from basal ganglia neurons recorded from locally anesthetized, immobilized rats. To determine whether these periodic oscillations are associated with similar periodicities in cortical activity, transcortical electroencephalographic (EEG) activity was recorded in conjunction with single- or dual-unit neuronal activity in the subthalamic nucleus (STN) or the globus pallidus (GP), and the data were analyzed with spectral and wavelet analyses. Multisecond oscillations in firing rates of 31% of the STN neurons and 46% of the GP neurons with periodicities significantly correlated with bursts of theta (4-7 Hz) activity in transcortical EEG. Further recordings of localized field potentials in the hippocampus and frontal or parietal cortices simultaneously with GP unit activity showed field potentials from the hippocampus, but not from the frontal or parietal cortices, exhibited bursts of theta rhythm that were correlated with GP firing rate oscillations. These results demonstrate a functional connectivity between basal ganglia neuronal activity and theta band activity in the hippocampus.

Animals↗
PubMedDate not supplied

[Morphological analysis of information processing in basal ganglia of mammals].

The article reviews published and own data on special features of organization of afferent cortical and infracortical correctional systems of the total striopallidaric nuclear complex in various species of mammals. The article focuses on analysis of organization of these flows in a dog being a classical object of behavioural experiments and a rare object of neuromorphological studies. It was discovered that the general trend towards segregated and converged flows of functionally different information at the level of striopallidum is retained in all tested mammals, being an evidence of the fundamental nature of the discussed principles of organization of the projection systems of basal ganglia. The reviewed morphological data confirm reliability of the presented concept of basal ganglia functioning.

Afferent Pathways↗
PubMed1988

Iron accumulation in the basal ganglia following severe ischemic-anoxic insults in children.

Increased iron deposition is described in four children following severe ischemic-anoxic insult and subsequent resuscitation. All cases demonstrated on T2-weighted magnetic resonance images areas of hypointensity in the basal ganglia, thalami, and white matter that were attributed to iron deposition. Associated areas of hyperintensity were also seen in the periventricular and subcortical white matter, and these were attributed to gliosis. In one case calcium deposition was also present within the areas of hypointensity. These findings suggest that after anoxic-ischemic damage, normal axonal transportation of brain iron can no longer occur. This may lead to increased accumulation of iron centrally at the sites of iron uptake in the basal ganglia and in the white matter. Additional iron deposition may occur more rapidly due to direct injury by lipid peroxidation degradation products catalyzed by iron.

Basal Ganglia↗
PubMed1985

The neostriatal mosaic: compartmental distribution of calcium-binding protein and parvalbumin in the basal ganglia of the rat and monkey.

Calcium-binding protein (CaBP) and parvalbumin are two proteins that are expressed in brain and bind calcium in the micromolar range. The immunohistochemical distribution of these two proteins was examined in the basal ganglia of rats and rhesus monkeys. In the striatum, CaBP immunoreactivity is localized to a subset of striatonigral projection neurons; CaBP-positive neurons are distributed in areas containing somatostatin-immunoreactive fibers and not in the complementary areas containing dense mu opiate-receptor binding. These biochemical labels mark, respectively, the matrix and patch compartments of the striatum. Previous studies have shown that striatal matrix neurons project to the substantia nigra pars reticulata, whereas striatal patch neurons project to the substantia nigra pars compacta. Consistent with the restricted localization of CaBP in the matrix projection neurons is the confinement of CaBP-immunoreactive afferent fibers to the pars reticulata. CaBP is also localized to a portion of dopaminergic and a few nondopaminergic neurons in the substantia nigra pars compacta and in most dopaminergic neurons in the ventral tegmental area. Parvalbumin immunoreactivity is localized to a subset of substantia nigra pars reticulata neurons and their axons. In the lateral striatum, some medium-sized aspiny interneurons are also parvalbumin immunoreactive. The distinct distributions of CaBP and parvalbumin in the basal ganglia are discussed in terms of their possible roles as intracellular calcium buffer systems related to the physiologic response properties of the neurons in which they are contained.

Animals↗
PubMed1999

Mitochondrial function is differentially altered in the basal ganglia of chronic schizophrenics.

In the present study, we have applied a novel strategy involving the postmortem measurement of the mitochondrial respiratory chain enzyme cytochrome-c oxidase (COX; complex IV) to identify regional changes in energy metabolism in the basal ganglia of chronic, medicated schizophrenics. COX activity was decreased in the caudate nucleus but increased in the putamen and nucleus accumbens. An increase in succinate dehydrogenase (complex II) was evident in the putamen and nucleus accumbens, but changes were not seen with NADH dehydrogenase (complex I). An analysis of interregional correlations in energy metabolism revealed several anomalies in the connections between the caudate and putamen and the globus pallidus in schizophrenics. Results provide strong evidence that changes in baseline energy metabolism in specific regions of the basal ganglia may exist in the disease. Based upon the high degree of input it receives from associative cortical areas, results suggest that a defect in the caudate may underlie certain aspects of cognitive decline in schizophrenics. In contrast, an increase in COX in the putamen, which receives extensive projections from the sensorimotor cortex, may reflect an effect of chronic neuroleptic treatment on motor function.

Adult↗
PubMed2004

Monitoring and switching of cortico-basal ganglia loop functions by the thalamo-striatal system.

Recent physiological and tract tracing studies revealed tight coupling of the centre médian and parafascicular nuclei (the CM-Pf complex), which are posterior intralaminar nuclei (ILN) of the thalamus, with basal ganglia circuits. These nuclei have previously been classified as part of the ascending reticulo-thalamo-cortical activating system, with studies of single neuron activity and of interruption of neuronal activity suggested that they participate in the processes of sensory event-driven attention and arousal, particularly in the context of unpredicted events or events contrary to predictions. In this article, we propose a hypothetical model that envisions that the CM-Pf complex functions in two different modes depending on the predictability of external events, i.e., one for monitoring 'top-down' biased control through the cortico-basal ganglia loop system for selecting signals for action and cognition and the other for switching from biased control to 'bottom-up' control based on the signals of salient external events. This model provides a new insight into the function of the CM-Pf complex and should lead to a better understanding of this important brain system.

Animals↗
PubMed1994

Hepatic encephalopathy with increased cerebral blood flow in SPECT and MRI abnormalities in the basal ganglia.

A case of hepatic encephalopathy with increased cerebral blood flow in single-photon emission computed tomography (SPECT) and abnormalities upon magnetic resonance imaging (MRI) is reported. SPECT showed increased blood flow exceeding 70 ml/100 g/min in the cerebellum, basal ganglia and cerebral cortex, with hyperammonemia and abnormal electroencephalographic signs showing severe generalized slowing. SPECT data and MRI might reflect abnormal metabolism and neuropathological changes in hepatic encephalopathy.

Antiparkinson Agents↗