Cerebral activation during bicycle movements in man

The cerebral activation during bicycle movements was investigated by oxygen -15-labelled H2O positron emission tomography (PET) in seven healthy human subjects. Compared to rest active bicycling significantly activated sites b ilaterally in the primary sensory cortex, primary motor cortex (M1) and sup plementary motor cortex (SMA) as well as the anterior part of cerebellum. C omparing passive bicycling movements with rest, an almost equal activation was observed. Subtracting passive from active bicycle movements, significan t activation was only observed in the leg area of the primary motor cortex and the precuneus, but not in the primary sensory cortex (S1). The M1 activ ation was positively correlated (alpha =0.75-0.85, t=6.4, P<10(-5)) with th e rate of the active bicycle movements. Imagination of bicycle movements co mpared to rest activated bilaterally sites in the SMA. It is suggested that the higher motor centres, including the primary and supplementary motor co rtices as well as the cerebellum, take an active part in the generation and control of rhythmic motor tasks such as bicycling.