A patchy horizontal organization of the somatosensory activation of the rat cerebellum demonstrated by functional MRI

Abstract

Blood oxygenation level dependent contrast (BOLD) functional MRI (fMRI) responses, in a 7-T magnet, were observed in the cerebellum of alpha-chloralose anaesthetized rats in response to innocuous electrical stimulation of a forepaw or hindpaw. The responses were imaged in both coronal and sagittal slices which allowed for a clear delineation and localization of the observed activations. We demonstrate the validity of our fMRI protocol by imaging the responses in somatosensory cortex to the same stimuli and by showing reproducibility of the cerebellar responses. Widespread bilateral activations were found with mainly a patchy and mediolateral band organization, more pronounced ipsilaterally. Possible parasagittal bands were observed only in contralateral lobule VI. There was no overlap between the cerebellar activations caused by forepaw and hindpaw stimuli. The overall horizontal organization of these responses was quite remarkable. For both stimulation paradigms most of the activation patches were positioned in either a rostral or caudal broad plane running anteroposteriorly through both anterior and posterior cerebellum. The rostral planes were completely separated, with the forepaw activation closer to the surface, while the caudal plane was common to both stimulation protocols. We relate our findings to the known projection patterns of spinocerebellar and cuneocerebellar mossy fibres, and to human fMRI studies.

CNS activation maps in awake rats exposed to thermal stimuli to the dorsum of the hindpaw

“…Both increased and decreased activation has been observed in human studies to noxious heat (Moulton et al, 2010) and has been reported in other rat fMRI studies of pain (Peeters et al, 1999). Increased activation in lobules 3, 4 and Crus 2 was observed in this study.…”

Mapping of the brain hemodynamic responses to sensorimotor stimulation in a rodent model: A BOLD fMRI study

“…In this study, our adjusted electrical stimulation elicited BOLD activations at cortical and subcortical levels confirming the activation of supraspinal structures namely S1, S2, M1, VPL, VA, VL and CPu (Fig 4). These results do not exclude spinal and cerebellar responses [24,25], two prerequisite structures relay that are not in the scope of the present work.…”

Modular organization of internal models of tools in the human cerebellum

“…Functional modularity on a fine scale has also been studied in these regions. Regarding parallel fiber inputs, somatotopic maps have been identified in the cerebellar cortex, but the map is fractured, that is, each small area of body surface is represented multiple times by spatially separated clusters of cells (4,5). Microzones, as long as several centimeters along the longitudinal axis of the cerebellar folia and as wide as 0.2 mm, have been identified for climbing fiber inputs as functional units (6).…”