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PubMed1994

Auditory tuning for spatial cues in the barn owl basal ganglia.

1. The basal ganglia are known to contribute to spatially guided behavior. In this study, we investigated the auditory response properties of neurons in the barn owl paleostriatum augmentum (PA), the homologue of the mammalian striatum. The data suggest that the barn owl PA is specialized to process spatial cues and, like the mammalian striatum, is involved in spatial behavior. 2. Single- and multiunit sites were recorded extracellularly in ketamine-anesthetized owls. Spatial receptive fields were measured with a free-field sound source, and tuning for frequency and interaural differences in timing (ITD) and level (ILD) was assessed using digitally synthesized dichotic stimuli. 3. Spatial receptive fields measured at nine multiunit sites were tuned to restricted regions of space: tuning widths at half-maximum response averaged 22 +/- 9.6 degrees (mean +/- SD) in azimuth and 54 +/- 22 degrees in elevation. 4. PA sites responded strongly to broadband sounds. When frequency tuning could be measured (n = 145/201 sites), tuning was broad, averaging 2.7 kHz at half-maximum response, and tended to be centered near the high end of the owl's audible range. The mean best frequency was 6.2 kHz. 5. All PA sites (n = 201) were selective for both ITD and ILD. ITD tuning curves typically exhibited a single, large "primary" peak and often smaller, "secondary" peaks at ITDs ipsilateral and/or contralateral to the primary peak. Three indices quantified the selectivity of PA sites for ITD. The first index, which was the percent difference between the minimum and maximum response as a function of ITD, averaged 100 +/- 29%. The second index, which represented the size of the largest secondary peak relative to that of the primary peak, averaged 49 +/- 23%. The third index, which was the width of the primary ITD peak at half-maximum response, averaged only 66 +/- 35 microseconds. 6. The majority (96%; n = 192/201) of PA sites were tuned to a single "best" value of ILD. The widths of ILD tuning curves at half-maximum response averaged 24 +/- 9 dB. 7. On average, sound level had no effect on a site's best ITD or best ILD nor did it affect ITD tuning widths. ILD tuning widths did, however, tend to increase slightly with sound level (average effect was 0.1 dB ILD/dB). 8. Most PA sites responded best to contralateral-ear leading ITDs with a majority being tuned to ITDs near 0 microsecond (corresponding to sound-source locations just contralateral to the midline).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2003

The primate basal ganglia: parallel and integrative networks.

The basal ganglia and frontal cortex operate together to execute goal directed behaviors. This requires not only the execution of motor plans, but also the behaviors that lead to this execution, including emotions and motivation that drive behaviors, cognition that organizes and plans the general strategy, motor planning, and finally, the execution of that plan. The components of the frontal cortex that mediate these behaviors, are reflected in the organization, physiology, and connections between areas of frontal cortex and in their projections through basal ganglia circuits. This comprises a series of parallel pathways. However, this model does not address how information flows between circuits thereby developing new learned behaviors (or actions) from a combination of inputs from emotional, cognitive, and motor cortical areas. Recent anatomical evidence from primates demonstrates that the neuro-networks within basal ganglia pathways are in a position to move information across functional circuits. Two networks are: the striato-nigral-striatal network and the thalamo-cortical-thalamic network. Within each of these sets of connected structures, there are both reciprocal connections linking up regions associated with similar functions and non-reciprocal connections linking up regions that are associated with different cortical basal ganglia circuits. Each component of information (from limbic to motor outcome) sends both feedback connection, and also a feedforward connection, allowing the transfer of information. Information is channeled from limbic, to cognitive, to motor circuits. Action decision-making processes are thus influenced by motivation and cognitive inputs, allowing the animal to respond appropriate to environmental cues.

Animals↗
PubMed2003

The basal ganglia: a neural network with more than motor function.

The basal ganglia is a group of subcortical nuclei involved in motor control, cognition, and emotion. Basal ganglia disorders are manifested by abnormal movement and a number of neuropsychiatric disorders. Basal ganglia nuclei are organized into sensorimotor, associative, and limbic territories based on their connectivity and function. The caudate nucleus, putamen, and subthalamic nucleus comprise the input nuclei of the basal ganglia. The internal segment of globus pallidus and substantia nigra reticulata are the output nuclei. The input and output nuclei are interconnected by direct and indirect pathways. The cerebral cortex, basal ganglia, and thalamus communicate with each other via closed (segregated) parallel as well as open (split) loops. Recent anatomic, functional, and clinical data have necessitated modifications in the classical models of local connectivity between input and output nuclei of the basal ganglia as well as in the corticobasal ganglia-thalamus-cortical loops.

Animals↗
PubMed1994

Basal ganglia: functional anatomy and physiology. Part 2.

Advances in knowledge about basal ganglia function and circuitry are reviewed. Despite the voluminous available literature on this subject, the role of basal ganglia in health and disease remains controversial. Experimental data on the effects of stimulation and ablation of the basal ganglia are summarized. The roles of the basal ganglia in the preparation for and execution of cortically initiated movement are described. Newer roles ascribed to the basal ganglia in sensory-motor gating, cognition, emotion, and motivation are discussed. The old and current concepts of information flow between the cerebral cortex, striatum, pallidum, thalamus, and back to the cerebral cortex are reviewed. The "funnel" system of information flow has been discarded in favor of several parallel and largely segregated loops pertaining to motor, oculomotor, cognitive, and limbic functions. The anatomic substrate of each of these loops is described. The specific roles of the striatum, pallidum, substantia nigra, and thalamus in information flow as related to movement are described. The roles of the basal ganglia in reinforcing wanted behavior and suppressing unwanted behavior via direct and indirect striatal loops are discussed. The implications of these loops in the genesis of Parkinson's disease and Huntington's chorea are described. Alteration in basal ganglia neurotransmitters and neuromodulators in Huntington's chorea, Tourette's syndrome, and Parkinson's disease are described.

Basal Ganglia↗
PubMed1998

[Calcinosis of the basal ganglia and hypoparathyroidism].

In most patients with basal ganglia calcification no disturbance of calcium metabolism is present. We present four patients with basal ganglia calcification. Two suffered from a secondary hypoparathyroidism following a complicated strumectomy years ago, one had an Alport-Syndrome and hypoparathyroidism. Her mother showed basal ganglia calcification and an abortive Alport-Syndrome as well, but no hypoparathyroidism.

Adult↗
PubMed1985

Basal ganglia calcification in Down's syndrome.

The basal ganglia from 33 patients (all over one year of age) with Down's syndrome were examined pathologically. Forty-five per cent had calcification. Basal ganglia calcification was localised to a constant area of globus pallidus and became more prominent with increased age. Calcification and amyloid degeneration of the adjacent blood vessels were present. The proximity of abnormal blood vessels to basal ganglia calcification suggests a pathogenetic relationship.

Adolescent↗
PubMed1979

Basal ganglia calcification in Down's syndrome.

Basal ganglia calcification has been observed in autopsy material of 7% of children suffering from Down's Syndrome. The incidence of this finding in the general neurological population is approx. 0.3%. The present report is the first case of Down's Syndrome with basal ganglia calcification diagnosed in life by computed axial tomography. This case illustrates that dense basal ganglia calcification can exist with no signs or symptoms of a movement disorder.

Adolescent↗
PubMed1990

Functional architecture of basal ganglia circuits: neural substrates of parallel processing.

Concepts of basal ganglia organization have changed markedly over the past decade, due to significant advances in our understanding of the anatomy, physiology and pharmacology of these structures. Independent evidence from each of these fields has reinforced a growing perception that the functional architecture of the basal ganglia is essentially parallel in nature, regardless of the perspective from which these structures are viewed. This represents a significant departure from earlier concepts of basal ganglia organization, which generally emphasized the serial aspects of their connectivity. Current evidence suggests that the basal ganglia are organized into several structurally and functionally distinct 'circuits' that link cortex, basal ganglia and thalamus, with each circuit focused on a different portion of the frontal lobe. In this review, Garrett Alexander and Michael Crutcher, using the basal ganglia 'motor' circuit as the principal example, discuss recent evidence indicating that a parallel functional architecture may also be characteristic of the organization within each individual circuit.

Animals↗
PubMed2025

Genetic background of neurological disorders with basal ganglia calcification.

BACKGROUND: Bilateral basal ganglia calcifications (BGCs), if severe, are known hallmarks for idiopathic BGC disease (IBGC), but if milder, are often considered radiological findings of unknown significance. In previous studies, only a minority of patients with BGC had monogenic forms of IBGC. METHODS: We studied consecutive patients from a tertiary neurology clinic with bilateral BGCs of variable severity, and their families. We analyzed known IBGC genes, and an extended panel of genes linked to monogenic stroke and metabolic conditions. Clinical, radiological, and genetic data were collected, including vascular risk factors, cerebrovascular events, imaging findings (total calcification score, white matter hyperintensities, ischemic/hemorrhagic lesions), and relevant family history. RESULTS: Twenty-four families with BGCs and neurological symptoms were analyzed. Disease-causing variants were identified in 14 families (58.3%). Eight patients had IBGC (variants in SLC20A2, PDGFB, MYORG), 4 had mitochondrial disease (MT-TL1), and 2 had monogenic vascular conditions (GAL, MAP3K6). Three variants were novel. BGC severity was highest in IBGC cases, while vascular and mitochondrial cases had milder calcifications. White matter hyperintensities were seen in 94.7% of cases and correlated highly with the total calcification score. Clinical vascular events had occurred in 41.7% cases. No monogenic cause was found in 10 patients, although many of these showed clinical or radiological features suggestive of monogenic disease. CONCLUSIONS: Bilateral BGCs can occur in many neurogenetic disorders apart from IBGCs, and a broader genetic search increases the diagnostic yield. Patients with BGCs frequently had clinical cerebrovascular events, which emphasizes the role of cerebrovascular pathology in BGCs.

Humans↗
PubMed2002

Cysticercosis lesions in basal ganglia are common but clinically silent.

Movement disorders due to basal ganglia involvement by neurocysticercosis are rarely seen. To evaluate the frequency of basal ganglia location of cysticercotic cysts and its clinical manifestations, baseline MRI scans of 120 consecutive patients with active neurocysticercosis were reviewed and the presence and number of active cysticercosis lesions (viable cysts or enhancing lesions) in the basal ganglia were recorded and correlated with demographic and clinical data. Basal ganglia involvement was found in 32 cases (26.7%). The frequency of lesions in basal ganglia was related to the total number of lesions, ranging from 5% of patients with a single cysticerci, to 60% in patients with more than five parasites. Putamen and caudate nuclei were the most frequent sites of lesions. No significant difference between both hemispheres was observed. Basal ganglia localization is common in neurocysticercosis but it is rarely associated with clinical manifestations.

Adolescent↗
PubMed2006

Evolution of basal ganglia surgery for movement disorders.

In 1942, it was thought that basal ganglia surgery would cause permanent unconsciousness and significant impairment of motor control. By 1947, when human stereotactic surgery was introduced, the first target was the globus pallidus in a patient with chorea. What happened during those 5 years to set the stage for stereotactic surgery? During the last half of the 19th century, it was first noted that motor disorders were often accompanied by atrophy of various parts of the basal ganglia, and when histopathology became part of necropsy, that relationship between movement disorders and the basal ganglia was strengthened. The impairment of fine motor control was noted in experiments that involved lesioning the basal ganglia, which led to the conclusion that disease of the basal ganglia might cause motor impairment. Finally, in 1939, Russel Meyers took the bold move of surgically resecting the head of the caudate nucleus at craniotomy in a patient with Parkinson's disease, demonstrating that Dandy was wrong in the view that the basal ganglia were the center of consciousness, and that symptoms and motor control might be improved by caudate lesions without motor impairment. He reported his first patient in a meeting in 1940, which was published in 1942, and was encouraged to investigate basal ganglia surgery further. Although results were encouraging, the mortality rate was prohibitive. Since the introduction of pallidoansotomy in 1947, basal ganglia surgery has become both safe and effective and has been expanded and refined.

Basal Ganglia Diseases↗
PubMed1993

Motor functions of the basal ganglia.

A study of movement disorders such as Parkinson's disease and Huntington's disease can provide an indication of the motor functions of the basal ganglia. Basal-ganglia diseases affect voluntary movement and can cause involuntary movement. Deficits are often manifested during the coordination of fine multi-joint movements (e.g., handwriting). The disturbances of motor control (e.g. akinesia, bradykinesia) caused by basal-ganglia disorders are illustrated. Data suggest that the basal ganglia play an important role in the automatic execution of serially ordered complex movements.

Basal Ganglia↗
PubMed2001

Comparison of the basal ganglia and cerebellum in shifting attention.

The basal ganglia and cerebellum have traditionally been associated with motor performance. Recently, there has been considerable interest regarding the contributions of these subcortical structures to aspects of cognition. In particular, both the basal ganglia and cerebellum have been hypothesized to be involved in the control of attentional set. To date, no neuropsychological studies have directly compared the effects of basal ganglia and cerebellar dysfunction on the same attention shifting tasks. To this end, we employed an alternating attention task that has been used to demonstrate putative attentional control deficits in children with cerebellar pathology, either related to autism or neurological insult. When adult patients with either Parkinson's disease or cerebellar lesions were tested on this task, a similar pattern of deficits was observed for both groups. However, when the motor demands were reduced, cerebellar patients showed a significant improvement on the alternating attention task, whereas the Parkinson patients continued to exhibit an impairment. This dissociation suggests that attentional deficits reported previously as being due to cerebellar dysfunction may be, at least in part, secondary to problems related to coordinating successive responses. In contrast, attention-shifting deficits associated with basal ganglia impairment cannot be explained by recourse to the motor demands of the task.

Acoustic Stimulation↗
PubMed2000

Laterality, somatotopy and reproducibility of the basal ganglia and motor cortex during motor tasks.

We investigated the basal ganglia, motor cortex area 4, and supplementary motor area (SMA) using functional magnetic resonance imaging (fMRI) and five motor tasks: switching between finger and toe movements, writing, finger tapping, pronation/supination, and saccadic eye movements. We found reliable activation in the caudate nucleus and putamen in single subjects without the need for inter-subject averaging. Percent signal changes in basal ganglia were smaller by a factor of three than those in SMA or motor cortex (1% vs. 2.5-3%). There was a definite foot-dorsal, hand-ventral basal ganglia somatotopy, similar to prior data from primates. Saccadic eye movements activated the caudate nucleus significantly more than the other tasks did. Unilateral movements produced bilateral activation in the striatum even when motor cortex activation was unilateral. Surprisingly, bilateral performance of the tasks led, on average, to consistently smaller basal ganglia activation than did unilateral performance (P<0.001), suggesting less inhibition of contralateral movements during bilateral tasks. Moreover, there was a striking dominance pattern in basal ganglia motor activation: the left basal ganglia were more active than the right for right handers, regardless of the hand used. This lateralization appears much stronger than that previously reported for motor cortex. Comparisons of inter-subject and intra-subject reproducibility indicated a much larger variability in basal ganglia and SMA compared to motor cortex, in spite of similar percent signal changes in the latter two structures.

Adult↗
PubMedDate not supplied

Neuropsychiatry of Huntington's disease and other basal ganglia disorders.

Degenerative diseases of the basal ganglia, such as Huntington's disease (HD), Parkinson's disease, and Wilson's disease, are characterized by motor, cognitive, and psychiatric manifestations. HD, in particular, can be considered a paradigmatic neuropsychiatric disorder that has all three components of the "Triadic Syndromes": dyskinesia, dementia, and depression. The authors examine the phenomenology, prevalence, and management of psychiatric disturbances occurring in diseases of the basal ganglia. They address psychiatric conditions such as depression, mania, psychosis, obsessive-compulsive disorders, aggression, irritability, apathy, sexual disorders, and delirium, discussing subtleties of diagnosis, and making reference to more unusual disorders of the basal ganglia, such as postencephalitic parkinsonism and Fahr's disease.

Basal Ganglia↗
PubMed2006

Structural analysis of the basal ganglia in schizophrenia.

Increases in the total volume of basal ganglia structures have been reported in schizophrenia. However, patterns of basal ganglia shape change, which can reveal localized changes in substructure volumes, have not been investigated. In this study, the total volume and shape of several basal ganglia structures were compared in subjects with and without schizophrenia. T(1)-weighted magnetic resonance scans were collected in 54 schizophrenia and 70 comparison subjects. High-dimensional (large-deformation) brain mapping was used to assess the shape and volume of several basal ganglia structures. The relationships of shape and volume measures with psychopathology, cognition and motor function were also assessed. Left and right volumes of the caudate and putamen, as well as the right globus pallidus volume, were significantly increased in subjects with schizophrenia as compared to comparison subjects after total brain volume was included as a covariate. Significant differences in shape accompanied these volume changes in the caudate, putamen and globus pallidus, after their total volumes were included as covariates. There were few significant correlations between volume or shape measures and either cognitive function or clinical symptoms, other than a positive correlation between an attention/vigilance cognitive dimension and the volume of the caudate and putamen, and a negative correlation between nucleus accumbens volume and delusions. In conclusion, basal ganglia volumes relative to total brain volume were larger in schizophrenia subjects than healthy comparison subjects. Specific patterns of shape change accompanied these volume differences.

Adult↗
PubMed2000

Reinforcement-driven dimensionality reduction--a model for information processing in the basal ganglia.

Although anatomical studies of the basal ganglia show the existence of extensive convergence and lateral inhibitory connections, physiological studies failed to show correlated neural activity or lateral interaction in these nuclei. These seemingly contradictory results could be explained with a model in which the basal ganglia reduce the dimensionality of cortical information using optimal extraction methods. Simulations of this model predict a transient change in the efficacy of the feed-forward and lateral synapses following changes in reinforcement signal, causing an increase in correlated firing rates. This process ultimately restores the steady-state situation with diminished efficacy of lateral inhibition and no correlation of firing. Our experimental results confirm the model's predictions: rate correlations show a drastic decrease between the input stage (cortex) and output stage (pallidum). Moreover, preliminary analysis revealed that pallidal correlations show a transient increase following discrepancies between the animal's predictions and reality. We therefore propose that by using a reinforcement-driven dimensionality reduction process the basal ganglia achieve efficient extraction of cortical salient information that may then be used by the frontal cortex for execution and planning of forthcoming actions.

Animals↗
PubMed2004

Effects of focal basal ganglia lesions on timing and force control.

Studies of basal ganglia dysfunction in humans have generally involved patients with degenerative disorders, notably Parkinson's disease. In many instances, the performance of these patients is compared to that of patients with focal lesions of other brain structures such as the cerebellum. In the present report, we studied the performance of patients with focal basal ganglia lesions on three fundamental motor tasks. The patients all had suffered unilateral damage in the striatum and were tested in the chronic state. The first task required the participants to tap with their index finger as fast as possible; this test provided a simple assessment of motor competence. Compared to controls, the maximum tapping rate was lower for the patients when tapping with their contralesional limb, although the deficit was not severe. The second and third tasks were designed to assess timing and force control, two functions that have been associated with basal ganglia function. The patients performed similar to controls on both tasks and showed no evidence of impairment when using their contralesional limb compared to their ipsilesional limb. The results indicate that unilateral basal ganglia lesions tend to produce minor motor problems in force control, and fail to support the hypothesized role of the basal ganglia in timing.

Aged↗