Alterations in forebrain catecholamine metabolism produced by cerebellar lesions in the rat

Distinct developmental changes in regional gray matter volume and covariance in individuals with attention-deficit hyperactivity disorder: A longitudinal voxel-based morphometry study

BACKGROUND

Very few studies have investigated longitudinal clinical cohorts of attention-deficit/hyperactivity disorder (ADHD). Moreover, how baseline brain changes could affect the development of ADHD symptoms later in life remains elusive. Therefore, we aimed to fill this gap by exploring brain and clinical changes in youth with ADHD using a longitudinal design.

METHODS

This prospective study consisted of 74 children and adolescents with ADHD and 50 age-, sex-, intelligence-matched typically developing controls (TDC), evaluated at baseline (aged 7-19 years) and re-evaluated 5.3 years later (a mean follow-up latency). We applied voxel-based morphometry to characterize brain structures, followed by both mass-univariate and multivariate structural covariance statistics to identify brain regions with significant diagnosis-by-time interactions from late childhood/adolescence to early adulthood. We used the cross-lagged panel model to investigate the longitudinal association between structural brain metrics and core ADHD symptoms.

RESULTS

The mass-univariate statistic revealed significant diagnosis-by-time interactions in the right striatum and the sixth lobule of the cerebellum. This was expressed by increased striatal and decreased cerebellar volume in ADHD, while TDC showed inverse volume changes over time. The multivariate method showed significant diagnosis-by-time interactions in a structural covariance network consisting of the regions involved in the functional sensory-motor and default-mode networks. Higher baseline right striatal and cerebellar volumes were associated with elevated ADHD symptoms at follow-up.

CONCLUSIONS

Our findings suggest a temporal association between the divergent development of striatal and cerebellar regions and dynamical ADHD phenotypic expression through young adulthood. These results highlight a potential brain marker of future outcomes.

Epigenetic Regulation of Neural Transmission after Cerebellar Fastigial Nucleus Lesions in Juvenile Rats

Structural and functional abnormalities in the cerebellar midline region, including the fastigial nucleus, have been reported in neuropsychiatric disorders, also comprising the cerebellar cognitive affecting syndrome. In rats, early fastigial lesions reduce social interaction during development and lead to cognitive and emotional deficits in adults, accompanied by compromised neuronal network activity. Since epigenetic mechanisms are implicated in the etiology of neuropsychiatric disorders, we investigated whether fastigial nucleus lesions in juvenile rats would impact epigenetic regulation of neural transmission. The fastigial nucleus was lesioned bilaterally in 23-day-old male rats. Sham-lesion and naïve rats served as controls. DNA methylation was investigated for target genes of the GABAergic, dopaminergic, glutamatergic and oxytocinergic systems in brain regions with anatomic connections to the fastigial nucleus, i.e., medial prefrontal cortex, nucleus accumbens, striatum, thalamus, and sensorimotor cortex. Protein expression was examined for the respective target genes in case of altered DNA methylation between lesion and control groups. Lesioning of the fastigial nucleus led to significant differences in the epigenetic regulation of glutamate decarboxylase 1 and the oxytocin receptor in the nucleus accumbens and the prefrontal cortex. No differences were found for the other target genes and brain regions. Our findings indicate that epigenetic dysregulation after lesioning of the fastigial nucleus may influence long-term recovery and the emergence of behavioral changes. Together with previous behavioral and electrophysiological investigations of this rat model, these observations can play a role in the cerebellar cognitive affective syndrome and other neuropsychiatric disorders.

Midline anomalies and organic psychosis: congenital or degenerative? A cross-sectional study of 62 patients with Andermann syndrome

Brain alterations have been sought since the beginning of the century to explain the ‘dementia’ of dementia præcox. Kraepelin suggested in 1913 that it might have its internal origins in early childhood, while Southard (1915) considered likely a congenital or early acquired basis for the development of the disease. Afterwards, degenerative processes were described for decades until neurodevelopmental theories emerged recently (Lewis, 1988).

Using pneumoencephalography, Jacobi and Winkler (1927) first reported that some patients with schizophrenia presented enlarged ventricles. Johnstone et al (1976, 1978), in CT-scan studies, observed an increase in mean lateral ventricular size in a group of institutionalized schizophrenic patients. This finding has been replicated by other studies (Weinberger et al, 1983) but challenged by others (Gluck et al, 1980; Jernigan et al, 1982).

Predictive Motor Timing and the Cerebellar Vermis in Schizophrenia: An fMRI Study

Abnormalities in both time processing and dopamine (DA) neurotransmission have been observed in schizophrenia. Time processing seems to be linked to DA neurotransmission. The cognitive dysmetria hypothesis postulates that psychosis might be a manifestation of the loss of coordination of mental processes due to impaired timing. The objective of the present study was to analyze timing abilities and their corresponding functional neuroanatomy in schizophrenia. We performed a functional magnetic resonance imaging (fMRI) study using a predictive motor timing paradigm in 28 schizophrenia patients and 27 matched healthy controls (HC). The schizophrenia patients showed accelerated time processing compared to HC; the amount of the acceleration positively correlated with the degree of positive psychotic symptoms and negatively correlated with antipsychotic dose. This dysfunctional predictive timing was associated with BOLD signal activity alterations in several brain networks, especially those previously described as timing networks (basal ganglia, cerebellum, SMA, and insula) and reward networks (hippocampus, amygdala, and NAcc). BOLD signal activity in the cerebellar vermis was negatively associated with accelerated time processing. Several lines of evidence suggest a direct link between DA transmission and the cerebellar vermis that could explain their relevance for the neurobiology of schizophrenia.

Automatic and controlled processing in the corticocerebellar system

During learning, performance changes often involve a transition from controlled processing in which performance is flexible and responsive to ongoing error feedback, but effortful and slow, to a state in which processing becomes swift and automatic. In this state, performance is unencumbered by the requirement to process feedback, but its insensitivity to feedback reduces its flexibility. Many properties of automatic processing are similar to those that one would expect of forward models, and many have suggested that these may be instantiated in cerebellar circuitry. Since hierarchically organized frontal lobe areas can both send and receive commands, I discuss the possibility that they can act both as controllers and controlled objects and that their behaviors can be independently modeled by forward models in cerebellar circuits. Since areas of the prefrontal cortex contribute to this hierarchically organized system and send outputs to the cerebellar cortex, I suggest that the cerebellum is likely to contribute to the automation of cognitive skills, and to the formation of habitual behavior which is resistant to error feedback. An important prerequisite to these ideas is that cerebellar circuitry should have access to higher order error feedback that signals the success or failure of cognitive processing. I have discussed the pathways through which such feedback could arrive via the inferior olive and the dopamine system. Cerebellar outputs inhibit both the inferior olive and the dopamine system. It is possible that learned representations in the cerebellum use this as a mechanism to suppress the processing of feedback in other parts of the nervous system. Thus, cerebellar processes that control automatic performance may be completed without triggering the engagement of controlled processes by prefrontal mechanisms.

Noradrenergic control of neuronal firing in cerebellar nuclei: modulation of GABA responses

The effects of noradrenaline (NA) on inhibitory responses to gamma aminobutyric acid (GABA) in neurones of the deep cerebellar nuclei were studied in vivo in rats, using extracellular single-unit recordings and microiontophoretic drug application. NA application altered GABA-evoked responses in 95 % of the neurones tested, but the effects differed between nuclei. Application of NA depressed GABA responses in the medial (MN) and posterior interpositus (PIN) nuclei, but enhanced GABA responses in the anterior interpositus nucleus (AIN). Comparable proportions of enhancing (57 %) and depressive (43 %) effects were found in the lateral nucleus (LN). The alpha2 noradrenergic receptor agonist clonidine mimicked the depressive effect of NA on GABA responses in MN and PIN and its enhancing effects in AIN and LN, while the alpha2 antagonist yohimbine partially blocked these effects. The beta-adrenergic agonist isoproterenol and antagonist timolol respectively induced and partially blocked enhancements of GABA responses in all nuclei except for LN, where isoproterenol had a weak depressive effect. It is concluded that NA modulates GABA responses by acting on both alpha2 and beta receptors. Activation of these receptors appears to be synergistic in the AIN and opposite in the remaining deep nuclei. These results support the hypothesis that the noradrenergic system participates in all the regulatory functions involving the cerebellum in a specific and differential manner, and suggest that any change in NA content, as commonly observed in ageing or stress, could influence cerebellar activity.

Gray matter volume abnormalities and externalizing symptoms in subjects at high risk for alcohol dependence

Reduced right amygdala volumes have been reported in young, alcohol-naïve subjects at high risk (HR) for alcohol dependence. The differences in brain morphometry have been associated with an excess of externalizing behaviors in these subjects. This may reflect a neurobiological vulnerability to alcohol dependence. Existing Magnetic Resonance Imaging (MRI) studies on these subjects have examined only a few, pre-selected brain regions using the manual regions of interest (ROI) approach. MRI of HR subjects (n = 20) and age, sex, and handedness-matched low-risk (LR) subjects (n = 21) were analyzed using optimized voxel-based morphometry and ROI approach. The externalizing symptoms of these subjects and their fathers were measured using the Semi-Structured Assessment for the Genetics of Alcoholism. HR subjects had significantly smaller volumes of superior frontal, cingulate and parahippocampal gyri, amygdala, thalamus and cerebellum. These gray matter volumes correlated negatively with externalizing symptoms scores. Subjects at HR for alcoholism have reduced volumes of critical areas of brain gray matter, which are associated with increased externalizing symptoms. These represent key endophenotypes of alcoholism.

A theoretical argument for inherited thiamine insensitivity as one possible biological cause of familial alcoholism

Thiamine deficiency has been specifically linked to the development of Wernicke-Korsakoff syndrome (WK)--a degenerative brain disorder that is typically associated with alcoholic drinking. Alcoholism-related thiamine deficiency is a major cause of WK. However, an inherited abnormality in thiamine utilization has been identified in some WK patients that may predispose heavy drinkers to this severe neurological syndrome. Individuals who possess this variant require more thiamine throughout their lives to prevent them from experiencing thiamine deficiency. Recent prospective studies have implicated early childhood nutritional and environmental influences in the etiology of alcoholism in adults. These studies have suggested that developmental abnormalities involving brain white matter growth might precipitate the later development of alcoholism possibly by altering the emerging reward-related brain systems. Brain white matter growth is highly sensitive to nutritional deficiency (including thiamine deficiency) and oxidative injury, especially during the perinatal period. The proposed model of familial alcoholism hypothesizes that an inherited insensitivity to thiamine can precipitate brain abnormalities very early in life that will greatly increase the risk of developing alcoholism in adulthood. This paper offers a heuristic model of a possible mechanism by which both inherited and environmental factors related to thiamine utilization might coaggregate to cause alcoholism.

Cerebellar vermis involvement in cocaine-related behaviors

Although the cerebellum is increasingly being viewed as a brain area involved in cognition, it typically is excluded from circuitry considered to mediate stimulant-associated behaviors since it is low in dopamine. Yet, the primate cerebellar vermis (lobules II-III and VIII-IX) has been reported to contain axonal dopamine transporter immunoreactivity (DAT-IR). We hypothesized that DAT-IR-containing vermis areas would be activated in cocaine abusers by cocaine-related cues and, in healthy humans, would accumulate DAT-selective ligands. We used BOLD fMRI to determine whether cocaine-related cues activated DAT-IR-enriched vermis regions in cocaine abusers and positron emission tomography imaging of healthy humans to determine whether the DAT-selective ligand [11C]altropane accumulated in those vermis regions. Cocaine-related cues selectively induced BOLD activation in lobules II-III and VIII-IX in cocaine users, and, at early time points after ligand administration, we found appreciable [11C]altropane accumulation in lobules VIII-IX, possibly indicating DAT presence in this region. These data suggest that parts of cerebellar vermis mediate cocaine's persisting and acute effects. In light of prior findings illustrating vermis connections to midbrain dopamine cell body regions, established roles for the vermis as a locus of sensorimotor integration and motor planning, and findings of increased vermis activation in substance abusers during reward-related and other cognitive tasks, we propose that the vermis be considered one of the structures involved in cocaine- and other incentive-related behaviors.

Developmental Differences in Childhood Motor Coordination Predict Adult Alcohol Dependence: Proposed Role for the Cerebellum in Alcoholism

BACKGROUND

The Danish Longitudinal Study of Alcoholism has identified a number of early biological indicators that predicted alcohol dependence 30 years later. In light of recent evidence linking deficits of the cerebellum to certain neuropsychiatric disorders often comorbid with alcoholism, we hypothesized that developmental deficits in the cerebellar vermis may also play a role in the initiation of adult alcohol dependence. The present study evaluated whether measures of motor development in the first year of life predict alcohol dependence three decades later.

METHODS

A total of 241 subjects of the original 330 infants who were entered into this study completed the 30-year follow-up (12 had died). The subjects were men who were drawn from a large birth cohort born in Copenhagen, Denmark, from 1959 to 1961. A comprehensive series of measures were obtained on each subject before, during, and shortly after birth as well as at 1 year of age. Muscle tone at birth and day 5 as well as 1-year measures of motor coordination--age to sitting, standing, and walking--were examined. A DSM-III-R diagnosis of alcohol dependence and a measure of lifetime problem drinking served as the 30-year outcome variables.

RESULTS

Several measures of childhood motor development significantly predicted alcohol dependence at 30 years of age. These included deficits in muscle tone 5 days after birth, delays in the age to sitting, and delays in the age to walking.

CONCLUSIONS

Relationships found between adult alcoholism and early delays in motor development offer support for the theory that cerebellar deficits may play a causal role in the addiction process.

Gross mapping of α1-adrenoceptors that regulate behavioral activation in the mouse brain

Brain alpha1-adrenoceptors that participate in behavioral activation were mapped in the mouse brain by determining where microinjection of the alpha1-antagonist, terazosin, inhibited behavioral activity in a novel cage test. A total of 5 out of 23 tested regions were shown to be involved including the dorsal pons/locus coeruleus region (DP/LC), the dorsal raphe/periaqueductal gray area (DR/PAG), the vermis cerebellum (CER), the nucleus accumbens (ACC) and the medial preoptic area (MPOA). Injection in the 4th ventricle was also effective perhaps by acting on several of these regions simultaneously. A partial inhibition was obtained from the motor cortex. Coinjection of the alpha1/2-agonist, 6-fluoronorepinephrine (6FNE) but not the alpha2-agonist, dexmedetomidine (DMT) reversed the behavioral inhibition in all regions. It is hypothesized that brain motoric alpha1-receptors elicit behavioral activation by coordinately exciting several monoaminergic, motor and motivational systems.

The cerebellum: organization, functions and its role in nociception

Our vision of the cerebellum has been gradually transformed throughout the last century from a 'little brain' to a 'neuronal machine' capable of multitasks, all arguably based on a principle computational model. We review here the main functions of the cerebellum in light of its organization and connectivity. In addition to providing a clear and extensive review of the cerebellar literature, we emphasize the role of the cerebellum in nociception, which is novel to the neurophysiology of pain. However, it is premature to conclude that the cerebellum influences sensory experience in the absence of clinical data.

Abnormal T2 relaxation time in the cerebellar vermis of adults sexually abused in childhood: potential role of the vermis in stress-enhanced risk for drug abuse

Recent studies suggest that childhood sexual abuse (CSA) elicits a cascade of neurohumoral events that affect brain development and is also a risk factor for the later development of substance abuse. We hypothesize that the cerebellar vermis may be a key region linking these observations. The vermis has a protracted ontogeny and a high density of glucocorticoid receptors, rendering it highly susceptible to early stress. The vermis modulates dopamine turnover in the accumbens and receives direct dopamine input through fibers with dopamine transporters. To test this hypothesis, steady-state functional magnetic resonance imaging (fMRI) (T2 relaxometry) was performed to assess resting blood flow in the vermis of 24 young adults (18-22 years) selected by screening from a large community sample. Eight subjects had a history of repeated CSA but were unmedicated and not under psychiatric care. Sixteen subjects were age-matched controls who had no personal or family history of Axis I psychiatric disorders. All subjects were screened to exclude known abnormalities affecting brain development, and any history of drug or alcohol abuse. CSA subjects had higher T2 relaxation time (T2-RT) than controls in the vermis but not in cerebral or cerebellar hemispheres. Vermal T2-RT correlated strongly with Limbic System Checklist (LSCL-33) ratings of temporal lobe epilepsy (TLE)-like symptomatology. From 537 prescreened young adults we found that their frequency of substance use was associated with a monotonic increase in LSCL-33 ratings and depression scores. Together these findings suggest that early trauma may interfere with the development of the vermis, and produce neuropsychiatric symptoms associated with drug use.

An MRI study of midbrain morphology in patients with schizophrenia: relationship to psychosis, neuroleptics, and cerebellar neural circuitry

BACKGROUND

The midbrain contains the perikarya of all the dopamine neurons in the human brain. Although other neurochemicals may well be involved, dopamine dysregulation is central in the pathophysiology of psychosis. Despite this, few imaging studies have evaluated the morphology of the midbrain.

METHODS

Using high-resolution magnetic resonance imaging, morphology of three posterior fossa and brain stem structures were measured: midbrain, pons, and medulla. The patient sample consisted of 50 men with schizophrenia, matched by gender and age to 50 healthy control subjects.

RESULTS

Patients had significantly smaller midbrain measures compared with control subjects. There were no differences between groups in measures of pons or medulla. Furthermore, midbrain size was significantly and inversely correlated with positive symptoms and cumulative neuroleptic exposure, but not with negative or disorganized symptoms. After controlling for the effect of cumulative neuroleptic exposure, the relationship between midbrain morphology and positive symptoms remained significant.

CONCLUSIONS

Midbrain morphology of patients with schizophrenia is abnormal, being smaller in patients compared with control subjects. Although this appears to be specifically related to psychotic symptoms, there is also a robust medication effect, with greater exposure to neuroleptics being associated with greater morphologic abnormality. We discuss the role of dopaminergic dysregulation and possible neural circuit involvement.

An MRI study of cerebellar vermis morphology in patients with schizophrenia: evidence in support of the cognitive dysmetria concept

BACKGROUND

Cumulative evidence suggests the cerebellum is involved in cognition and may be important in the pathoetiology of schizophrenia. Functional imaging studies have identified a possible neural circuit that includes the cerebellum and may be abnormal in patients with schizophrenia, manifesting as a fundamental cognitive deficit conceptualized as cognitive dysmetria. To explore the role of the cerebellum in cognitive dysfunction and schizophrenia, this study was designed to evaluate the morphology of the cerebellar vermis, its relationship to other cortical areas, and to cognitive function in patients with schizophrenia.

METHODS

Male patients with schizophrenia (n = 65) were matched by age and gender to 65 healthy male controls. Volume measures of the 4 cerebral lobes and total cerebellum were obtained using automated methods. The area of the cerebellar vermis (divided into three lobes) was traced on a midsaggital MRI slice.

RESULTS

Patients had smaller frontal and temporal lobes. There were no group differences in total cerebellar volume. Patients had a smaller vermis area, accounted for by a smaller anterior lobe. The anterior vermis area was positively correlated with total cerebellar volume, temporal lobe volume, and FSIQ in patients, but not controls.

CONCLUSIONS

These findings support the theory that regions of the cerebellum may be involved in a neural circuit that is structurally and functionally abnormal in patients with schizophrenia, leading to cognitive dysmetria.

The anatomy of mood disorders--review of structural neuroimaging studies

The structural neuroimaging findings in mood disorders were reviewed, to evaluate evidence for a neuroanatomic model of pathophysiology, involving the prefrontal cortex, the basal ganglia, the amygdala-hippocampus complex, thalamus, and connections among these structures. Global atrophy is not consistently found. The best replicated finding is an increased rate of white matter and periventricular hyperintensities. A smaller frontal lobe, cerebellum, caudate, and putamen appear present in unipolar depression. A larger third ventricle, and smaller cerebellum and perhaps temporal lobe appear present in bipolar disorder. These localized structural changes involve regions that may be critical in the pathogenesis of mood disorders. Generalized and localized anatomic alterations may be related to age or vascular disease. The clinical and biological correlates of these changes need to be investigated to allow development of a more complete model of pathophysiology of mood disorders.

Improvement in word-fluency performance in Parkinson's disease by administration of electromagnetic fields

The association between degeneration of the nigrostriatal dopamine (DA) system and the motor manifestations of Parkinson's disease (PD) provided the impetus for the development of DA replacement therapy. However, clinical experience has demonstrated that DA-ergic drugs, while attenuating the motor symptoms of PD, have little or no consistent effect on the mental and cognitive symptoms of the disease which are thought to be related partly to degeneration of the meso-cortico-limbic DA system. Thus, failure of DA-ergic drugs to improve the mental and cognitive deficits of PD indicates that these agents cannot fully restore DA functions in the meso-cortico-limbic circuits. The present communication concerns five fully medicated Parkinsonian patients in whom application of a series of treatments with electromagnetic fields (EMF) of extremely low intensity (in the picotesla range) and frequency (5-8Hz) produced a dramatic improvement in performance on Thurstone's World-Fluency Test, a sensitive marker of frontal lobe functions. These findings suggest that in contrast to DA replacement therapy application of low intensity EMF may improve frontal lobe functions in patients with PD presumably by augmenting DA activity in the mesocortical system. As deficiency of the frontal DA system has been implicated also in the development of akinesia and freezing in PD these observations may explain the beneficial effects of EMF on the motor manifestations of the disease.

Psychotic behavior associated with cerebellar pathology

This report concerns a 27-year-old man in whom psychotic behavior emerged in association with a cerebellar tumor. This presentation supports previous clinical observations which postulate an intimate relationship between cerebellar pathology and the development of schizophrenia.

Dopaminergic innervation and binding in the rat cerebellum

In the present study, we used an antiserum against dopamine (DA), and specific [3H]ligands in order to shed more light on the dopaminergic system of the rat cerebellum. The immunocytochemical approach showed that the entire rat cerebellum is innervated by DA fibers. All cerebellar layers were found to receive a considerable amount of DA afferents but the molecular layer was the most heavily innervated. The analysis of [3H]DA and [3H]spiperone binding showed that in the rat cerebellum there exists DAergic binding with kinetic parameters similar to those reported for the mouse cerebellum. The results of the present study support the existence of a DA system in the rat cerebellum.

Transection of the superior cerebellar peduncle interferes with the onset and duration of generalized seizures induced by amygdaloid kindling

We studied the effect of transections at the superior cerebellar peduncle during the evolution of amygdaloid kindling. Dentato- and interposito-thalamic pathways, including the ascending fastigial fibers, were transected in 10 rats at the contralateral side of the stimulated amygdala, and in other 8 at the ipsilateral side. A group of 18 rats was used as control. Contralateral lesion significantly slowed amygdala kindling, while ipsilateral lesion decreased kindled seizure duration. Furthermore, when kindled seizures were reached by 6 control rats, transection of the ipsilateral superior cerebellar peduncle led to reduction of subsequent seizures. These specific effects produced by transection of the superior cerebellar peduncle suggest that the cerebellum could exert a tonic effect over the participating circuitry used by the kindling process.

Neuroradiological facets of cognitive abnormality in schizophrenia

Cognitive abnormality has long been regarded as a core feature of schizophrenia, but its nature and etiopathology have been poorly understood. Predicated on new tests that characterize fundamental cognitive impairments, we investigated their relationship to four neuroradiological markers that have been previously implicated in schizophrenia: choroid plexus calcification, cerebellar atrophy, third ventricle enlargement, and pineal calcification. Twenty-three chronic schizophrenic inpatients meeting RDC and DSM-III diagnostic criteria were stabilized on chlorpromazine and assessed independently on a cognitive battery and on CT scan. The results indicated that all four neuroradiological variables were independent of one another and of demographic, historical, and general intellectual measures. The neuroradiological assessments, however, correlated significantly with different cognitive parameters, implying separate pathophysiological bases for distinct profiles of cognitive abnormality. The findings support a "dual-process model" of cognitive dysfunction that posits developmental and arousal-related components which may, more generally, underlie the positive-negative dimension of schizophrenia.

Atrophy of the cerebellar vermis: relevance to the symptoms of schizophrenia

Degeneration of the cerebellar vermis is a common pathological and neuroradiological feature of chronic schizophrenia, but its relationship to symptoms of the disease are poorly understood. We investigated the relationship of vermal cerebellar atrophy on CT scan to features of positive (productive) and negative (defect) dimensions of schizophrenia as well as to symptoms of general psychopathology in a sample of 23 chronic schizophrenic patients. For comparison, we also studied the relationship of third ventricular width (TVW), which reflects periventricular and diencephalic atrophy, to these features of schizophrenic symptomatology. Vermal cerebellar atrophy was found in 43.5% of patients and correlated significantly with general psychopathology and, more specifically, with feelings of guilt and disturbance of volition. It was unrelated to global positive or negative features of schizophrenia. By contrast, TVW was uniquely associated with global negative syndrome. These observations indicate that degeneration of the cerebellar vermis and enlargement of the third ventricle are integral aspects of schizophrenia, and that each contributes independently to specific clinical aspects of the disease.

Noradrenergic systems in human cerebellum

Thin, beaded axons, immunostained with antisera to human dopamine beta-hydroxylase (DBH), were present in all layers of the anterior vermis of human cerebellum. This plexus appears similar to that described in rodents and provides information complementary to receptor autoradiographic studies that show significant noradrenergic innervation of mammalian cerebellum. Moreover, in two aged controls, we demonstrated abnormal, swollen, tortuous axons not visualized in young controls.

Cerebellar vermal size predicts drug response in schizophrenic patients: a magnetic resonance imaging (MRI) study

1. In schizophrenic patients, a good drug response was associated with a small cerebellar vermis brain ratio (CVBR). 2. It was possible to predict drug response with a higher statistical significance based on CVBR, especially in nonfamilial patients with schizophrenia.

Kinetic and pharmacologic characterization of dopamine binding in the mouse cerebellum and the effects of the reeler mutation

The purpose of this study was to characterize the dopaminergic system in the mouse cerebellum and to determine whether the dyskinesia of the reeler mutant is accompanied by alterations in cerebellar and/or striatal dopamine binding. From the analysis of (3H) dopamine ((3H)DA) and (3H)spiperone ((3H)Sp) binding, the study of the effects of several drugs on this binding, and the comparison of these parameters between the cerebellum and striatum, we conclude that a dopaminergic system exists in the cerebellum with properties common to the striatal system but also with some differences. That is, 1) with (3H)DA as ligand, we find two binding sites in cerebellum with similar Kd to those of striatum but of lower density, 2) with (3H)Sp as ligand we observe two binding sites in cerebellum and one in striatum, and 3) the competition of (3H)DA binding by various drugs shows that among the cerebellar sites, relative to striatum, there is a higher proportion that corresponds to high affinity D3 and D4 (D2 high) binding sites. In cerebellum and striatum of reeler mice, (3H)DA binding increases 125-174% and 14%, respectively.

Paleocerebellar stimulation induces in vivo release of endogenously synthesized [3H]dopamine and [3H]norepinephrine from rat caudal dorsomedial nucleus accumbens

The influence of cerebellar vermis stimulation on noradrenergic and dopaminergic activity in the nucleus accumbens was investigated in anesthetised rat. Artificial cerebral spinal fluid containing [3H]tyrosine was continuously circulated through a unilateral push-pull cannula implanted in the nucleus accumbens. Fifteen-minute perfusate samples were collected serially for three consecutive 1-h periods designated pre-, during-, and post-stimulation. The stimulation was applied through a bilateral electrode located subdurally over the fifth vermal lobe. The [3H]norepinephrine and [3H]dopamine components in each sample were isolated by alumina extraction and high-pressure liquid chromatographic fractionation, and then quantified by liquid scintillation counting. For cannula locations in the caudal dorsomedial nucleus accumbens, levels of both [3H]catecholamines were found to be significantly higher during stimulation compared to the prestimulation baselines, and [3H]norepinephrine remained significantly elevated through the post-stimulation period. The relative increase during stimulation for [3H]norepinephrine (130%) was nearly twice that for [3H]dopamine (70%). These results indicate that vermal activation can significantly raise both noradrenergic and dopaminergic in vivo activity in the caudal dorsomedial nucleus accumbens, and provide a possible mechanism for explaining previously demonstrated influences of paleocerebellum upon affective components of behavior.

Lack of effect of cerebellectomy on ascending dopaminergic neurons in the rat brain

The dopamine content in striatum and substantia nigra of the rat was not altered 3 weeks after total or hemicerebellectomy. Furthermore, 3 days after hemicerebellectomy basal and haloperidol-stimulated activity of ascending mesolimbic and nigrostriatal dopaminergic neurons, as estimated from the in vivo rate of dopamine synthesis in striatum and nucleus accumbens, was not altered. Cupric silver degeneration staining following hemicerebellectomy failed to identify a direct anatomical pathway between cerebellum and substantia nigra in the rat.

Cerebellar pathology in schizophrenia--cause or consequence?

Atrophy of the cerebellar vermal cortex has been reported to occur in 10% or more of patients with schizophrenia. Data from studies on experimental animals indicate that a functional relationship between the cerebellum and parts of the forebrain involved in emotion exists, and that the cerebellum may influence some types of behavior. Cerebellar abnormality in schizophrenic patients, although of uncertain cause, could contribute to the symptomatology of the disease.

Effect of cerebellar lesions on monoamine levels in various brain areas of the cat

Modifications in thee content of monoamines after different lesions of the cerebellar cortex were investigated in eight prosencephalic structures of cat's brain. Apart from other minor changes, lesions of the posterior vermis induced significant changes in the thalamus (decrease of DA and increase of 5-HT). Lesions of the cortex of a cerebellar hemisphere, on the other hand, produced an increase of 5-HT in the caudate nucleus and an increase of DA in the hippocampus in addition to a generalized increase of 5-HT in all the prosencephalic structures studied. These findings are discussed in relation to the anatomical connections of the lesioned areas and their expected role in the sleep-wakefulness cycle.

Changes in dopamine release in caudate nuclei and substantia nigrae after electrical stimulation of the posterior interposate nucleus of cat cerebellum

The effect of unilateral electrical stimulation of the posterior interposate nucleus of the cerebellum was examined on the activity of the nigro-striatal dopaminergic pathways on both sides of the brain in alpha-chloralose anaesthetized cats. Push-pull cannulae were inserted into both caudate nuclei and both substantia nigrae to measure the release of [3H]dopamine ( [3H]DA) which was continuously synthesized from L-[3,5-3H]tyrosine. The stimulation of the cerebellum induced long-lasting well-organized changes in [3H]DA release in the four structures: an increased release of the neurotransmitter in both the contralateral caudate nucleus and the ipsilateral substantia nigra and a reduction in the release of DA from the ipsilateral caudate nucleus and the contralateral substantia nigra. This finding supports the concept of a functional interaction between the cerebellum and the basal ganglia.

Kainic acid: enduring alterations in cerebellar morphology and in cerebral catecholamine and GABA concentrations after cerebellar injection in the rat

Kainic acid injected locally in the vermian cortex produces a focal lesion with severe cellular loss. Microscopic changes in 3-week-old preparations are given for both central and peripheral segments. Biochemical studies indicate that norepinephrine, dopamine and gamma-aminobutyric acid (gaba) concentrations in the forebrain are consistently higher on the side of the lesion and remain elevated for at least 3 weeks. It is postulated that disinhibition of cerebellar activity traversing the uncrossed pathway from cerebellar nuclei to catecholamine cell bodies was a major mechanism causing increased catecholamine metabolism in the ipsilateral forebrain.

Release of dopamine in both caudate nuclei and both substantia nigrae in response to unilateral stimulation of cerebellar nuclei in the cat

The effects of unilateral focal electrical stimulation of the deep cerebellar nuclei on the activity of the nigrostriatal dopaminergic neurons on both sides of the brain were examined in halothane anaesthetized cats. For this purpose, push-pull cannulae were inserted into both caudate nuclei and both substantia nigrae, and the release of [3H] dopamine ([3H]DA) continuously formed from [3,5-3H]L-tyrosine was estimated in superfusates. The unilateral electrical stimulation of the right cerebellar dentate nucleus induced a long-lasting increase in the release of [3H]DA in the left caudate nucleus and a simultaneous decrease in the release of [3H]transmitter in the right caudate nucleus. These changes were associated with opposite fluctuations in the release of [3H]DA from the corresponding substantia nigrae. Thus, the electrical stimulation of the right dentate nucleus induced a pronounced decrease in the release of the [3H]-amine in the [3H]transmitter in the corresponding substantia nigra, whereas the activity of the contralateral substantia nigra, whereas the release in the ipsilateral substantia nigra was simultaneously increased. In contrast, the unilateral electrical stimulation of the right cerebellar fastigial nucleus resulted only in an increased release of [3H]DA in the ipsilateral (right) caudate nucleus, associated with a decreased release of the [3H]transmitter in the corresponding substantia nigra, whereas the activity of the contralateral (left) dopaminergic system was not significantly affected. These results support a direct functional interaction between the cerebellum and the basal ganglia. They also suggest that the release of DA from dopaminergic axonal terminals is inversely correlated to the extent of the transmitter release from dendrites.