Neuroradiological correlates of neuropsychological disorders in olivopontocerebellar atrophy (OPCA)

The lateralized linguistic cerebellum: a review and a new hypothesis

During the past 2 decades the collaboration across disciplines and the methodologic and conceptual advances of contemporary neuroscience have brought about a substantial modification of the traditional view of the cerebellum as a mere coordinator of autonomic and somatic motor functions. Growing insights in the neuroanatomy of the cerebellum and its interconnections, evidence from functional neuroimaging and neurophysiological research, and advancements in clinical and experimental neuropsychology have established the view that the cerebellum participates in a much wider range of functions than conventionally accepted. This increase of insight has brought to the fore that the cerebellum modulates cognitive functioning of at least those parts of the brain to which it is reciprocally connected. This article reviews the recently acknowledged role of the cerebellum in cognition and addresses in more detail experimental and clinical data disclosing the modulatory role of the cerebellum in various non-motor language processes such as lexical retrieval, syntax, and language dynamics. In agreement with the findings indicating a topographical organization of the cerebellar structures involved in language pathology we advance the concept of a "lateralized linguistic cerebellum." In our view crossed cerebral diaschisis processes, reflecting a functional depression of supratentorial language areas due to reduced input via cerebellocortical pathways, might represent the relevant pathomechanism for linguistic deficits associated with cerebellar pathology.

Olivopontocerebellar atrophy and Friedreich's ataxia: neuropsychological consequences of bilateral versus unilateral cerebellar lesions

This chapter deals with neuropsychological disturbances in patients with bilateral cerebellar damage (BCD), i.e., epileptic patients chronically receiving phenytoin, patients with olivopontocerebellar atrophy (OPCA), and Friedreich's ataxia (FA) versus those with unilateral cerebellar damage (UCD), i.e., patients with cerebellar strokes. BCD patients showed: (i) impaired executive functions in planning and programming of daily activities, elaborating and using structures, and difficulty in abstract thinking, functions that are related to cerebello-frontal loops; (ii) deficits in visuospatial organization for a concrete task and deficient visual-spatial working memory, functions related to cerebello-parietal loops; (iii) lower general intellectual abilities than controls (especially those with OPCA); (iv) difficulties with memory retrieval, diminished global memory quotient, and reduced spatial working memory ability; and (v) slower speed of information processing, as measured by simple and multiple choice reaction time (RT). In UCD patients, neuropsychological and neurobehavioral abilities were deficient for 2-5 months; after this time period, their performances returned to normal. In both BCD and UCD patients, single photon emission computed tomography (SPECT) studies showed different degrees of "reverse" cerebellar-->basal ganglia-->frontoparietal diaschisis which may underlie permanent or transitory neuropsychological deficits. The relationships among neuropsychological findings, SPECT studies, and chemical neuroanatomy are discussed.