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PubMed1996

The frontal cortex-basal ganglia system in primates.

The primate basal ganglia receives information from most of the cerebrum, including the frontal cortex, but projects (via the dorsal thalamus) primarily to the frontal lobe, perhaps in its entirety. As such, the frontal cortex and basal ganglia constitute an integrated, distributed neuronal architecture. We review evidence that the frontal lobe and basal ganglia specialize in different, but related, aspects of response learning. Frontal cortex acts when new rules need to be learned and older ones rejected, whereas the basal ganglia potentiate previously learned rules based on environmental context and reinforcement history. Such potentiation increases the probability that the central nervous system will select a particular rule to guide behavior. We outline a possible mechanism for the basal ganglia's proposed role in rule potentiation, one that involves both the direct and indirect striatal output pathways and their dopaminergic input. It has previously been proposed that direct-pathway neurons recognize a pattern of corticostriatal inputs, which promotes activity in recurrent, positive-feedback modules (or loops) of which they are an integral part. We propose that this recurrent activity potentiates a rule associated with those modules. If so, then the dopaminergic system is well situated and organized to modulate rule potentiation in both the short and long term. Dopaminergic neurons of the midbrain increase activity during learning and other periods of relatively unpredictable reinforcement. Dopamine enhances gene expression and other forms of activity in striatal neurons of the direct pathway, while suppressing neurons of the indirect pathway. In the short term, then, dopamine may augment the activity of modules triggered by a recognized context, whereas in the long term it may promote context-dependent activation of the same modules. Together, these modulatory influences could support both rule potentiation and learning the context for potentiating that rule.

Animals↗

PubMedDate not supplied

[Depression and calcinosis of the basal ganglia: apropos of a case].

Idiopathic basal ganglia calcifications is a heterogeneous entity characterized by the association of bilateral and symmetric calcifications of the basal ganglia and the dentae nuclei in the cerebellum, polymorphous neuropsychiatric symptomatology. It is rare, of unknown etiology and often hereditary. We report the case of a 48 years old man, who presented with melancholic depression which has been steadily worsening for more than a year and which had led to a serious suicide attempt. Clinical observation revealed apragmatism, affective dullness and impoverished spontaneous expression; the theme of incapacity predominated but guilt feelings were absent. Neurologic examination was normal except for extra-pyramidal signs. CT-scan revealed the presence of bilateral and extensive calcifications of caudate nuclei, lenticular nuclei and thalamus, which indicated a diagnosis of idiopathic basal ganglia calcification characterized by depression. Moreover, MRI revealed an hypersignal of the white periventricular substance. Phospho-calcic results and the parathormone dosage were normal. Psychometric tests showed that although intellectual capacity seemed to be intact, it was not utilised in practice. Unresponsive to antidepressants and sismotherapy, the patient is still the same one and a half year later, and needs to remain in an institution. Subsequent tests indicate that intellectual deterioration has begun. This case poses the problem of the relationship between depressive syndrome and basal ganglia lesions. We look at studies bearing on this subject and on other clinically similar syndromes (athymhormia, loss of psychic self-activation), in which the interruption or cortico-striato-pallido-thalamo-cortical circuits (particularly the limbic loop), is a physiopathologic mechanism currently invoked.

Basal Ganglia↗

PubMed1998

Microcircuitry of the direct and indirect pathways of the basal ganglia.

Our understanding of the organization of the basal ganglia has advanced markedly over the last 10 years, mainly due to increased knowledge of their anatomical, neurochemical and physiological organization. These developments have led to a unifying model of the functional organization of the basal ganglia in both health and disease. The hypothesis is based on the so-called "direct" and "indirect" pathways of the flow of cortical information through the basal ganglia and has profoundly influenced the field of basal ganglia research, providing a framework for anatomical, physiological and clinical studies. The recent introduction of powerful techniques for the analysis of neuronal networks has led to further developments in our understanding of the basal ganglia. The objective of this commentary is to build upon the established model of the basal ganglia connectivity and review new anatomical findings that lead to the refinement of some aspects of the model. Four issues will be discussed. (1) The existence of several routes for the flow of cortical information along "indirect" pathways. (2) The synaptic convergence of information flowing through the "direct" and "indirect" pathways at the single-cell level in the basal ganglia output structures. (3) The convergence of functionally diverse information from the globus pallidus and the ventral pallidum at different levels of the basal ganglia. (4) The interconnections between the two divisions of the pallidal complex and the subthalamic nucleus and the characterization of the neuronal network underlying the indirect pathways. The findings summarized in this commentary confirm and elaborate the models of the direct and indirect pathways of information flow through the basal ganglia and provide a morphological framework for future studies.

Animals↗

PubMed1989

Role of basal ganglia in saccades.

The basal ganglia, substantia nigra pars reticulata (SNr) and caudate nucleus, contribute to the suppression and initiation of saccadic eye movements by imposing a tonic inhibition on the superior colliculus (SC) and by removing it. The tonic inhibition originates from the SNr where neurons show continuous, high frequency discharges. With its inhibitory connection to the SNr, the caudate nucleus transiently suppresses the SNr activity thereby removing the tonic inhibition on the SC. Signals carried by neurons in the SNr and the caudate nucleus are both heavily dependent on or selective for different aspects of learned paradigms. Such task-specific, learned information originating from the basal ganglia may open or close the gate for a variety of excitatory inputs to the SC.

Animals↗

PubMed2004

A dystonic syndrome associated with anti-basal ganglia antibodies.

Anti-basal ganglia antibodies (ABGA) have been associated with movement disorders (usually tics and chorea) and psychiatric disturbance in children. This report describes five adult and adolescent patients (one male, four females; mean age of onset, 16 years (range, 13-35)) who presented subacutely with a clinical syndrome dominated by dystonia and had ABGA binding to antigens of similar molecular weights to those seen in Sydenham's chorea. Three patients had a clear history of respiratory infection before the onset of their symptoms. Three patients received immunosuppressive treatment, with three showing a notable reduction in symptoms. It is hypothesised that dystonia in adults or adolescents may be part of the clinical spectrum of the post-infectious syndrome associated with ABGA.

Adolescent↗

PubMed1993

Phosphoinositide second messenger system is enriched in striosomes: immunohistochemical demonstration of inositol 1,4,5-trisphosphate receptors and phospholipase C beta and gamma in primate basal ganglia.

The neurochemical organization of the basal ganglia has been studied extensively with respect to neurotransmitters, neuropeptides, and their receptors. The chemoarchitecture of the striatum has been found particularly striking, because it distinguishes many substances by their relative distributions within the striosome and matrix compartments of the striatum. Very little is yet known about the differential distribution of second messenger systems in the basal ganglia, however, and no information is available about whether the distribution of second messenger systems is related to the prominent neurochemical compartmentalization of the striatum. We have examined the distribution of the phosphoinositide second messenger system in the primate basal ganglia and substantia nigra, as detected with polyclonal antisera against the inositol 1,4,5-trisphosphate receptor (IP3R), and monoclonal antisera against phospholipase C beta (PLC beta) and phospholipase C gamma (PLC gamma). In the striatum, immunostaining for each of the three proteins was present predominantly in medium-sized neuronal perikarya and in the neuropil. Circumscribed zones of enhanced IP3R, PLC beta, and PLC gamma immunoreactivity appeared in a background of generally weaker staining, and these zones corresponded to striosomes as identified by calbinidin D28k and substance P immunostaining in adjacent sections. Thus, the richest representation of the phosphoinositide system in the primate striatum appears to be in striosomes. In the substantia nigra pars compacta, neurons and neuropil were immunopositive, but in the substantia nigra pars reticulata and in each segment of the globus pallidus, immunostaining was mainly confined to the neuropil. Perikaryal PCL gamma immunoreactivity in the absence of detectable PLC beta or IP3R immunolabeling was found in the magnocellular neurons embedded in the medullary layer between the putamen and the globus pallidus. These observations demonstrate that the phosphoinositide second messenger system is selectively enhanced in neuronal subsystems of the basal ganglia, including striosomes, and suggest that signaling by phosphoinositide pathways elicits discrete effects on input-output processing by the basal ganglia.

Animals↗

PubMed1983

The cortical relationships of certain basal ganglia and the cholinergic basal forebrain nuclei.

Three groups of subcortical nuclei are related to the entire cerebral cortex, to the allocortex of the hippocampus and olfactory areas as well as the neocortex. The medial septal nucleus, the nucleus of the diagonal band and the basal nucleus send cholinergic fibers to the cortex: the striatum, neo- and ventral, receives fibers from the cortex and the claustrum has reciprocal cortical connections. In their neocortical relationships there are marked similarities between these groups.

Acetylcholine↗

PubMed2006

The basal ganglia in human learning.

For many years, the basal ganglia were described in anatomy courses as strictly motor structures. Certainly, some of the most obvious and debilitating symptoms shown by persons with basal ganglia disorders are problems in motor control. However, the basal ganglia are not limited to motoric aspects of behavior: recent research shows that they are involved in most areas of cognitive and emotional functioning, consistent with their anatomical connections with all areas of the cortex. This review will focus on the roles of the basal ganglia in human learning, particularly sequence learning and category learning. Current areas of research that are discussed include the differing roles of different basal ganglia regions, patterns of interaction between the cortex and basal ganglia, differences in positive and negative association learning, effects of dopaminergic medication on learning, whether basal ganglia-mediated learning is implicit or explicit, and how the basal ganglia learning systems interact with other learning systems, particularly within the medial temporal lobe.

Basal Ganglia↗

PubMed1988

Idiopathic basal ganglia calcification and organic mood disorder.

Idiopathic basal ganglia calcification is a syndrome consisting of bilateral basal ganglia calcifications, neuropsychiatric abnormalities, disturbances of movement, and normal calcium and phosphorus metabolism. The best described neuropsychiatric alterations are dementia and an organic psychosis. Organic mood disorder has been reported less often, and mania secondary to idiopathic basal ganglia calcification has not been noted previously. The authors describe five patients with idiopathic basal ganglia calcification and organic mood changes, including one patient with secondary mania. Symptoms of idiopathic basal ganglia calcification resemble those of other disorders affecting subcortical structures and support an association between mood, affect, cognition, and the extrapyramidal nuclear system. Treatment may ameliorate the mood disorder.

Adult↗

PubMed1991

[Bilateral traumatic hemorrhage in the basal ganglia: report of two cases].

Hematomas of the basal ganglia in head injury have long been recognized by pathologists with an interest in head injury but their mechanism has not been revealed clearly. We report two cases of bilateral traumatic hemorrhage in the basal ganglia. Case #1, a 17-year-old male was admitted to our hospital immediately after a traffic accident. Neurological examination revealed that the patient was comatose and had right hemiparesis. CT scan showed bilateral hemorrhage of the basal ganglia and subarachnoid hemorrhage in the perimesencephalic cistern. MRI showed high signal intensity areas in the bilateral basal ganglia, perimesencephalic cistern, cerebral white matter and corpus callosum. The patient was diagnosed as having diffuse axonal injury coinciding with bilateral hemorrhage of the basal ganglia. Stereotactic aspiration for the hematoma of the left basal ganglia was carried out. Case #2, a 75-year-old male was admitted immediately after falling from the roof of his house. Neurological examination revealed no neurological deficit except for headache and nausea. CT scan on the day of injury revealed no abnormality. But CT scan 12 hours following the injury showed bilateral hemorrhage of the basal ganglia. Blood pressure of the patient was within normal range and he was diagnosed as having traumatic bilateral intracerebral hematoma. Conservative treatment was carried out and the patient was discharged 7 days after injury with no neurological deficit. The mechanism of traumatic hemorrhage of the basal ganglia has not been clear. In case #1, diffuse axonal injury (DAI) may have played an important role in the bilateral hemorrhage. But in case #2, non-DAI factor such as vasoparalysis syndrome may have existed.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidental Falls↗

PubMed1981

The significance of the incidental finding of basal ganglia calcification on computed tomography.

Basal ganglia calcification was found as an incidental finding in 42 out of 7000 patients who underwent computed tomography. The calcification showed on plain skull radiography when the maximum density on computed tomography exceeded 100 Hounsfield units. The 26 patients with basal ganglia calcification detected on computed tomography who were available for follow-up, were investigated with matched controls. No clinical features of basal ganglia calcification were noted. Twenty-four patients had no significant metabolic abnormality and two patients had parathyroid disorder identified.

Basal Ganglia Diseases↗

PubMed1998

Neuronal circuitry and synaptic connectivity of the basal ganglia.

The concept of organization of the basal ganglia has changed markedly over the last 10 years. These developments have led to the introduction of a schematic model of the functional circuitry of the basal ganglia that accounts for normal and abnormal basal ganglia functions. The recent introduction of powerful techniques for the analysis of neuronal networks has led to many new developments in our understanding of the anatomic and synaptic organization of the basal ganglia. The objective of this article is to go from the established model of the basal ganglia connectivity to new anatomic findings that lead to reconsideration and refinement of some aspects of the models.

Basal Ganglia↗

PubMed2004

Directional analysis of coherent oscillatory field potentials in the cerebral cortex and basal ganglia of the rat.

Population activity in cortico-basal ganglia circuits is synchronized at different frequencies according to brain state. However, the structures that are likely to drive the synchronization of activity in these circuits remain unclear. Furthermore, it is not known whether the direction of transmission of activity is fixed or dependent on brain state. We have used the directed transfer function (DTF) to investigate the direction in which coherent activity is effectively driven in cortico-basal ganglia circuits. Local field potentials (LFPs) were simultaneously recorded in the subthalamic nucleus (STN), globus pallidus (GP) and substantia nigra pars reticulata (SNr), together with the ipsilateral frontal electrocorticogram (ECoG) of anaesthetized rats. Directional analysis was performed on recordings made during robust cortical slow-wave activity (SWA) and "global activation". During SWA, there was coherence at approximately 1 Hz between ECoG and basal ganglia LFPs, with much of the coherent activity directed from cortex to basal ganglia. There were similar coherent activities at approximately 1 Hz within the basal ganglia, with more activity directed from SNr to GP and STN, and from STN to GP rather than vice versa. During global activation, peaks in coherent activity were seen at higher frequencies (15-60 Hz), with most coherence also directed from cortex to basal ganglia. Within the basal ganglia, however, coherence was predominantly directed from GP to STN and SNr. Together, these results highlight a lead role for the cortex in activity relationships with the basal ganglia, and further suggest that the effective direction of coupling between basal ganglia nuclei is dynamically organized according to brain state, with activity relationships involving the GP displaying the greatest capacity to change.

Action Potentials↗

PubMed2003

Anatomical MRI study of basal ganglia in major depressive disorder.

The basal ganglia form a part of the brain neuroanatomic circuits that may be involved in mood regulation. Decreases in basal ganglia volumes have been previously reported in major depressive disorder patients in comparison to healthy controls. In this study, we measured caudate, putamen, and globus pallidus volumes in 25 patients with major depressive disorder (4 M; age+/-S.D.=41+/-11 years) and 48 healthy controls (29 M; age+/-S.D.=35+/-10 years), using high-resolution magnetic resonance imaging (MRI), in an attempt to replicate prior findings. Unlike most previous studies, we did not find significant differences between patient and control groups in basal ganglia volumetric measures. Nonetheless, there was a significant interaction between diagnosis and cerebral hemisphere, with MDD patients showing decreased asymmetry in globus pallidus volumes in comparison with healthy controls. Furthermore, in the patient group, left putamen volumes correlated inversely with length of illness, and left globus pallidus volume correlated directly with number of prior depressive episodes. These findings suggest that abnormalities in lateralization and possibly neurodegenerative changes in basal ganglia structures participate in the pathophysiology of major depressive disorder.

Adolescent↗

PubMed1996

The basal ganglia: focused selection and inhibition of competing motor programs.

The basal ganglia comprise several nuclei in the forebrain, diencephalon, and midbrain thought to play a significant role in the control of posture and movement. It is well recognized that people with degenerative diseases of the basal ganglia suffer from rigidly held abnormal body postures, slowing of movement, involuntary movements, or a combination of these a abnormalities. However, it has not been agreed just what the basal ganglia contribute to normal movement. Recent advances in knowledge of the basal ganglia circuitry, activity of basal ganglia neurons during movement, and the effect of basal ganglia lesions have led to a new hypothesis of basal ganglia function. The hypothesis states that the basal ganglia do not generate movements. Instead, when voluntary movement is generated by cerebral cortical and cerebellar mechanisms, the basal ganglia act broadly to inhibit competing motor mechanisms that would otherwise interfere with the desired movement. Simultaneously, inhibition is removed focally from the desired motor mechanisms to allow that movement to proceed. Inability to inhibit competing motor programs results in slow movements, abnormal postures and involuntary muscle activity.

Animals↗

PubMed2002

Functional anatomy of the basal ganglia.

Four organizational levels of the basal ganglia that could be particularly determinant in terms of functional properties are reviewed: (1) macroscopic anatomy, which is characterized by a dramatic decrease of cerebral tissue volume from the cerebral cortex to the deepest portions of the basal ganglia; (2) connectivity, which consists of both complex loops and a partition into three territories, sensorimotor, associative, and limbic (which process motor, cognitive, and emotional information, respectively); (3) neuronal morphology, characterized by a dramatic numeric and geometric convergence of striatal neurons onto pallidonigral neurons; and (4) dopaminergic innervation of the basal ganglia, which is organized as a dual system that is supposed to have opposite effects on the activity of the system. Current models of the basal ganglia are discussed.

Animals↗

PubMed2004

Genetic heterogeneity in familial idiopathic basal ganglia calcification (Fahr disease).

Familial idiopathic basal ganglia calcification (IBGC, Fahr disease) is an inherited neurologic condition characterized by basal ganglia and extra-basal ganglia brain calcifications, parkinsonism, and neuropsychiatric symptoms. The authors examined six families for linkage to the previously identified genetic locus (IBGC1) located on chromosome 14q. The authors found evidence against linkage to IBGC1 in five of the six families supporting previous preliminary studies demonstrating genetic heterogeneity in familial IBGC.

Basal Ganglia Diseases↗

PubMed1983

Auditory cortical field projections to the basal ganglia of the cat.

Projections to the basal ganglia from four auditory cortical fields in the cat were studied by combining microelectrode-mapping of the neurons' best frequencies with autoradiographic and histochemical tract-tracing techniques. Each auditory field is a source of projections to the homolateral basal ganglia. The distribution of labeling within the basal ganglia is related to the cortical field in which the injection site is located. The dorsal portion of the putamen and adjacent caudate nucleus are connected with cortical fields situated anteriorly and dorsally, while the ventral portion of the putamen and adjacent lateral amygdaloid nucleus are related to auditory fields situated posteriorly and ventrally. Injections of two different tracers into different best-frequency loci of one cortical field provided evidence that low best-frequency neurons project medially within the basal ganglia while high best-frequency neurons project more laterally. We concluded that there was a basic similarity among patterns of terminations in the basal ganglia from axons that originate in different auditory cortical fields. When the source of a projection was confined to a restricted portion of an auditory cortical field, labeling appeared as dense patches of silver grains separated from each other by areas of less dense labeling. Often, these patches were distributed within a sheet of tissue, elongated both dorsoventrally and anteroposteriorly. Loci having the same best-frequency representation, but situated in different auditory cortical fields, project upon overlapping but not coextensive portions of a single sheet of tissue. Thus the projections from geographically distant cortical loci possessing similar best-frequency representations are notably distinguished on a topographic basis. By comparison, two adjacent sheets of tissue were labeled when two injections were made into the low best-frequency and high best-frequency representations of the same auditory field. Double-injection, double-tracer experiments revealed that adjacent sheets of tissue received projections from different best-frequency loci. These observations suggested a degree of tonotopic organization to this projection system which was equipoise to the evidence obtained for a topographic organization.

Animals↗