Elliott L. Mancall

Differential Localization of Class III β-Tubulin Isotype and Calbindin-D28k Defines Distinct Neuronal Types in the Developing Human Cerebellar Cortex

This immunohistochemical study compares the localization of the neuronal class III β-tubulin isotype (βIII) to that of calbindin-D28k in 40 human fetal and postnatal cerebella ranging from 12 weeks gestation to adulthood. In the external granule layer of the developing cerebellar cortex, βIII staining was present in the premigratory (postmitotic) zone of horizontal neurons but was absent in “epithelioid” cells of the subpial proliferative mitotic zone. In the molecular layer, intense βIII staining was associated with parallel fibers, stellate/basket neurons and migrating fusiform granule neurons. βIII staining was also present in internal granule neurons. In contrast, βIII was not detectable in fetal and neonatal Purkinje neurons and Golgi II neurons, but was evident in these neurons from juvenile and adult cerebella. Calbindin-D28k staining was present in Purkinje neurons also delineating their somatic spines (“pseudopodia”), lateralizing and apical dendrites (including dendritic spines), subpopulations of small to intermediate-sized Golgi II neurons in the internal granule layer (“synarmotic cells” of Landau), large to medium-sized subcortical Golgi II neurons and neurons of cerebellar roof nuclei, at various gestational stages and postnatally. It was absent in the external granule layer, parallel fibers, stellate/basket and internal granule neurons. Variable degrees of βIII and calbindin-D28k staining were detected in subpopulations of immature neuroepithelial cells of the ventricular matrix at the roof of the fourth ventricle. Glial (including Bergmann glia) and mesenchymal cells were not stained for either antigenic determinants. The differential expression of calbindin-D28k and βIII defines distinct populations of neurons in the developing human cerebellar cortex and supports the ontogenetic concept of Ramon y Cajal.

Somatosensory evoked potentials in Huntington's disease ☆

Scalp recorded somatosensory evoked potentials (SEPs) elicited by left and right median nerve stimulation were obtained in 21 patients with Huntingtons disease (HD), 14 individuals at risk (AR) for HD, and 21 non-patient controls matched for age and sex. Although SEP abnormalities were not uniform in the HD group, no HD patient had SEPs that conformed fully to the normal configuration with respect to peak latencies, presence of all components and spatial distribution. The most common abnormality was non-specific in nature, consisting of amplitude reduction or virtual abscence of components after 100 msec. More specific deviations were noted in the early SEP events. In half of the HD patients, peak P30 seemed to occur at approximately 45 msec poststimulus; this peak could have been taken as the normal P45 had it not reversed in phase between the central and frontal leads. In these cases peak P45 prepared to be missing. Peak N20 latency values were longer in the HD group than in the non-patient controls, whereas the P15 latencies did not differ significantly. The conduction time between P15 and N20 was significantly longer in HD patients than the non-patient controls. SEPs of the majority of the ARs were similar to those of the non-patients controls in terms of overall configuration, although mean amplitudes were generally lower for ARs than non-patient controls and 4 ARs exhibited prolonged P15-N20 latency differences.

Auditory and visual evoked potentials in Huntington's disease

Auditory and visual evoked potentials elicited by acoustic click (AEP) and checkerboard pattern flash (VEP) were recorded from 15 locations in 21 patients with Huntingtons disease (HD) and 21 controls matched for age and sex. Peak latencies were approximately the same for both groups, except that AEP peak N100 appeared earlier in HDs. The main deviation in HDs consisted of generally reduced amplitude of VEP and AEP components; these deviations can be considered non-specific. Early VEP and AEP peaks contained no specific abnormalities comparable to those found in early somatosensory evoked potentials, as previously reported for the same subjects. VEP and AEP amplitudes were lower in medicated than in unmedicated HD patients, but amplitudes for both medicated and unmedicated HDs deviated from normal. Drugs may act to further diminish the already lower than normal amplitudes in HDs.

Sexual Dysfunction in Neurological Disease

Disorders of sexual function in the human result from a remarkable variety of structural lesions involving the nervous system. Sexual dysfunction is widely recognized as a reflection of disorders of the peripheral nervous system and of the spinal cord; however, it is less widely appreciated that lesions of the cerebral hemispheres may also produce changes in this respect, at times so startling, dramatic, or bizarre as to be regarded, albeit inappropriately, as psychogenic in origin. It is tempting to suggest a simple dichotomy in this respect: lesions in the peripheral nervous system might be expected to induce disorders of potency, involving erection, ejaculation, or both, whereas lesions of the central nervous system, and particularly of the cerebral hemispheres, might be anticipated to result in disorders of libido, i.e., of sexual energy and desire. This division may be valid to a point but, as will be seen, does not really hold up to critical scrutiny, and in general, one cannot determine with certainty, on the basis of the type of sexual disorder alone, the site of neural involvement in any given patient.