Structural and Functional Relationships Between Cerebellum and Catecholamine Systems: An Overview. In: Palay SL, Chan-palay V, editors. The Cerebellum—New Vistas. Berlin: Springer Berlin Heidelberg; 1982. pp. 587-606. [DOI: 10.1007/978-3-642-68560-6_28]

Emotional task-dependent low-frequency fluctuations and methylphenidate: Wavelet scaling analysis of 1/f-type fluctuations in fMRI of the cerebellar vermis

Ion channel currents, neural firing patterns, and brain BOLD signals display 1/f-type fluctuations or fractal properties in time. By design, fMRI methods attempt to minimize the contribution of variance from low-frequency physiological 1/f-noise. New fMRI methods are described to visualize and measure 1/f-type BOLD fluctuations in volunteers recalling affectively neutral or emotional memories or meditating (i.e., attending to breathing) then retrospectively rating emotional content. A wavelet scaling exponent (alpha) was used to characterize signals from 0.015625 to 0.5Hz in cerebellar lobules VIII to X of the vermis (posterior inferior vermis; PIV), a region coordinating balance, eye tracking, locomotion, and vascular tone, and a possible site of pathology in attention deficit hyperactivity disorder (ADHD).

RESULTS

Changes in alpha and emotional measures were correlated in PIV voxels (r = 0.622, d.f .= 14, P < 0.0005), but not other regions examined. In contrast, conventional means and standard deviations of PIV voxels were unchanged. Methylphenidate, shown to decrease slow oscillations in rodent basal ganglia [Ruskin DN, Bergstrom DA, Shenker A, Freeman LE, Baek D, Walters JR. Drugs used in the treatment of attention-deficit/hyperactivity disorder affect postsynaptic firing rate and oscillation without preferential dopamine autoreceptor action. Biol Psychiatry 2001;49:340-50.], abolished task-dependent alpha changes in the PIV of an adult with ADHD. Wavelet analysis of long BOLD time series appears well suited to fractal physiology and studies of pharmacologically modulated cerebellar-thalamic-cortical function in ADHD or other psychiatric disorders.

Microanatomical localization of dopamine receptor protein immunoreactivity in the rat cerebellar cortex

Dopamine (DA) receptor subtype localization was investigated in rat cerebellar cortex using immunohistochemical techniques with antibodies raised against D1-D5 receptor protein. A faint D1 receptor protein immunoreactivity was developed in molecular and Purkinje neurons layers. D2 receptor protein immunoreactivity was found primarily in cerebellar white matter followed by molecular and granular layers and Purkinje neurons. Antibodies against D2S receptor protein were localized in molecular layer and to a lesser extent, in granular layer. A few Purkinje neurons displayed a faint D2S receptor protein immunoreactivity. D3 receptor protein immunoreactivity was observed primarily in molecular and in Purkinje neurons layers of lobules 9 and 10. A faint D3 receptor protein immunoreactivity was also localized in Purkinje neurons and to a lesser extent, in molecular and granular layers of cerebellar lobules 1-8. D4 receptor protein immunoreactivity was found in cerebellar white matter. A pale immunostaining was also visualized in molecular layer. D5 receptor protein immunoreactivity was localized primarily in molecular and Purkinje neurons layers and to a lesser extent, in granular layer and in white matter. The above results indicate that rat cerebellar cortex expresses the DA receptor subtypes so far identified. Purkinje neurons, which are the only efferent neurons of cerebellum, are richest in DA receptor protein immunoreactivity. This suggests that dopaminergic neurotransmission may modulate efferent inputs from cerebellum. The localization of the majority of D2 and D4 and of a faint D5 protein receptor immunoreactivity in cerebellar white matter suggests that these receptors may be presynaptic and transported axonally.

Identification of age-related changes of dopamine D1-like receptors in the rat cerebellar cortex

The present study was designed to characterize the pharmacological profile of dopamine D1-like receptors in the rat cerebellar cortex and to assess if these receptor sites undergo age-related changes. Cerebella of young (3 months), adult (12 months), and old (27 months) male Wistar rats were examined by using radioligand binding techniques and light microscope autoradiography. The non-selective dopamine D1-like radioligand [3H]SCH 23390 was specifically bound to sections of rat cerebellum. The findings that dopamine displaced [3H]SCH 23390 binding in the submicromolar range suggest that labelling of a dopamine D5 (or D1B) receptor subtype. The affinity of [3H]SCH 23390 for dopamine D1-like receptors was similar in the cerebellar cortex of the three animal groups investigated, whereas radioligand binding techniques revealed a gradual age-related reduction of the density of binding sites. Light microscope autoradiography showed the localization of [3H]SCH 23390 binding sites primarily in the molecular layer and to a lesser extent in the Purkinje neuron layer of the cerebellar cortex. Aging was accompanied by a loss of [3H]SCH 23390 binding sites affecting mainly the molecular layer. The age-dependent loss of dopamine D1-like receptors is more pronounced if detected with radioligand binding techniques than with light microscope autoradiography. This suggests that the decrease of dopamine D1-like receptors observed in aging rat cerebellar cortex may depend in part on changes in the receptor expression and in part on cortico-cerebellar structural changes.

Cerebellar cortical and nuclear afferents from the feline locus coeruleus complex

The origin and distribution of cerebellar cortical and nuclear afferents from the locus coeruleus complex (the nucleus locus coeruleus, the nucleus subcoeruleus, the medial and lateral subdivisions of the parabrachial nucleus and the Kölliker-Fuse nucleus) have been studied by means of retrograde transport of the wheat germ agglutinin-horseradish peroxidase complex in the cat. Cerebellar cortical depositions of the tracer were made by pressure injections, while nuclear depositions were made by implanting the tracer in crystalline form. The projection is bilateral with an ipsilateral preponderance. It reaches all the cerebellar nuclei as well as vermal, intermediate and lateral parts of the cerebellar cortex. The highest cell counts were made after tracer depositions in vermal and intermediate parts of the cerebellum. The projection in the cat has a more widespread origin than previously reported. It originates mainly within the nucleus locus coeruleus and the parabrachial nucleus (especially in its lateral subdivision), but retrogradely labelled neurons were also found in nucleus subcoeruleus, the Kölliker-Fuse nucleus and the A4 cell group. The cells of origin were of different shapes, but usually had a maximum diameter of the cell body between 15 and 30 micron. Cerebellar efferent axons passing through the locus coeruleus complex were anterogradely labelled following implants in all the cerebellar nuclei, but definite terminal labelling was not observed within the nuclei of the locus coeruleus complex.

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.

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.