Regional differences in Purkinje cell morphology in the cerebellar vermis of male mice

Abstract

Regional differences in dendritic architecture can influence connectivity and dendritic signal integration, with possible consequences for neuronal computation. In the cerebellum, analyses of Purkinje cells (PCs), which are functionally critical as they provide the sole output of the cerebellar cortex, have suggested that the cerebellar cortex is not uniform in structure as traditionally assumed. However, the limitations of traditional staining methods and microscopy capabilities have presented difficulties in investigating possible local variations in PC morphology. To address this question, we used male mice expressing green fluorescent protein selectively in PCs. Using Neurolucida 360 with confocal image stacks, we reconstructed dendritic arbors of PCs residing in lobule V (anterior) and lobule IX (posterior) of the vermis. We then analyzed morphologies of individual arbors and the structure of the assembled "jungle," comparing these features across anatomical locations and age groups. Strikingly, we found that in lobule IX, half of the reconstructed PCs had two primary dendrites emanating from their soma, whereas fewer than a quarter showed this characteristic in lobule V. Furthermore, PCs in lobule V showed more efficient spatial occupancy compared to lobule IX, as well as greater packing density and increased arbor overlap in the adult. When analyzing complete ensembles of PC arbors, we also observed "hot spots" of increased dendritic density in lobule V, whereas lobule IX showed a more homogeneous spread of dendrites. These differences suggest that input patterns and/or physiology of PCs could likewise differ along the vermis, with possible implications for cerebellar function.

Functionally distinct Purkinje cell types show temporal precision in encoding locomotion

“…The Purkinje cell population is well characterized in fish and mammals ( 3 , 10 , 22 – 24 , 27 , 30 , 33 , 35 , 36 , 43 , 44 ), but little is known of its intrapopulation differences ( 45 – 47 ). Purkinje cell compartmentalization was previously observed through ZebrinII expression ( 32 ).…”

Electrophysiological Excitability and Parallel Fiber Synaptic Properties of Zebrin-Positive and -Negative Purkinje Cells in Lobule VIII of the Mouse Cerebellar Slice

“…However, the present results showed that the zebrin type of PCs was not tightly linked with different input resistances in lobule VIII, suggesting that differences in input resistance might reflect lobular organization and other factors. Recently, it has been reported that the morphology of PC dendritic arbor is significantly different among lobules and among locations in a lobule (Nedelescu et al, 2018). Such morphological differences may affect the PC input resistance rather than expression of molecules that is linked to the zebrin type.…”

Cerebellar Morphometry and Cognition in the Context of Chronic Alcohol Consumption and Cigarette Smoking

“…2). Although the vermis has the same cell types as the flocculonodular, anterior, and posterior lobes of the cerebellum, there is some evidence in mice that the morphology of Purkinje cells may be different in the vermis (Nedelescu et al, 2018), potentially offering some explanation as to why our vermis measures were not smaller in smokers. Another possibility is that smoking affects the lateral boundaries of the vermis, which are extraordinarily difficult to measure reliably and are not reflected in our midsagittal vermis cross-sectional area.…”