Anatomical And Functional Relationships Between Deep Cerebellar Nuclei And Trigeminal Tactile Response Area Of Cerebellar Cortex In Vivo In Mice

ObjectiveWe previously reported that an air-puff stimulation on the ipsilateral whisker pad inhibited both molecular layer (ML) and PC layer in cerebellar cortex folium Crus II. However, the relationship between these PCs and their projection site in DCN are unclear. In this study, we investigate that the anatomical and functional relationships between the tactile response area in cerebellar cortex Crus II and DCN in vivo mice.Methods1. Electrophysiological recording, using electrophysiological technique to record the field potential of the PC from the cerebellar cortex Crus II and DCN.2. Anterograde tracing methods, injection of biotinylated dextran amine (BDA) to study the regions of PC projection to DCN.3. Identify the location of the injection, using methylene blue staining the injection site of BDA in vivo mice.4. Histochemical, the mice were deeply anesthetized with chloral hydrate 4 or 5 days after injecting BDA. Transcardially perfuse 4% paraformaldehyde and cut the head post-fixed in the fixative at 4℃ for 3-4 days. Following the coronal sections of 200 μm thickness, biocytin staining and take the image of the site of projection.ResultsWe found that the tactile-inhibited PC axons projected in anterior part (IntA) and posterior part (IntP), and dorsolateral hump (IntDL) of ipsilateral interposed cerebellar nucleus (ICN). In ICN, the tactile stimulus evoked-field potential expressed a sequence of two negative components Nl, N2. The extracellular recordings from ICN neurons shown that the stimulation evoked increased in spike firing rate of ICN neurons, which expressed two peaks. The minimum duration of facial air-puff stimulation for evoking field potentials in ICN was 5ms, which expressed single peak response; when the air-puff stimulus durations were≥30 ms, stimulation off response (Roff) were observed in the ICN. An increase in the duration of facial air-puff stimulation did not significantly affect the amplitude of Ron (Nl and N2) and Roff. In addition, the latency and time to peak of N1 in ICN were significantly faster than that of N1 in the ML, but the latency and time to peak of N2 in ICN were significantly later than that of P1 in the ML.ConclusionThe projection areas of trigeminal tactile areas of the cerebellar cortex crus II PCs are mainly in lateral parts of ipsilateral ICN. And the facial sensory information, at least in part, is transferred to ICN by PC axons from Crus II, which evokes excitation in ICN neurons.