In vivo imaging of neuronal activation and plasticity in the rat brain by high resolution positron emission tomography (microPET)

The study of neural repair and neuroplasticity in rodents would be enhanced by the ability to assess neuronal function in vivo. Positron emission tomo graphy (PET) is used to study brain plasticity in humans, but the limited r esolution and sensitivity of conventional scanners have generally precluded the use of PET to study neuroplasticity in rodents. We now demonstrate tha t microPET, a PET scanner developed for use with small animals, can be used to assess metabolic activity in different regions of the conscious rodent brain using [F-18]fluorodeoxyglucose (FDG) as the tracer, and to monitor ch anges in neuronal activity. Limbic seizures result in dramatically elevated metabolic activity in the hippocampus, whereas vibrissal stimulation resul ts in more modest increases in FDG uptake in the contralateral neocortex. W e also show that microPET can be used to study lesion-induced plasticity of the brain. Cerebral hemidecortication resulted in diminished relative gluc ose metabolism in the neostriatum and thalamus ipsilateral to the lesion, w ith subsequent, significant recovery of metabolic function. These studies d emonstrate that microPET can be used for serial assessment of metabolic fun ction of individual, awake rats with a minimal degree of invasiveness, and therefore, has the potential for use in the study of brain disorders and re pair.