Involvement of multiple functionally distinct cerebellar regions in visual discrimination: a human functional imaging study.
We investigated the contribution of the human cerebellum to cerebral function during visual discrimination using PET and fMRI. The cognitive task was a successive discrimination of shades of brown with a parametric variation of the stimulus presentation rate and a constant task difficulty. The successive color discrimination task was contrasted to a dimming detection control task, with identical retinal input but with double the number of motor responses. Three sets of activated cerebellar and cerebral regions were observed: rate-dependent and rate-independent color discrimination networks and a motor-and-detection network. The rate-dependent color discrimination network included both an anterior and a posterior activation site in lobule-VI of the two lateral cerebellar hemispheres, whereas the rate-independent network involved a bilateral activation site in lateral Crus-I. Cerebellar sites of the motor-and-detection network were located in medial lobule-V bilaterally, in the vermis, and in posterior left Crus-I and right Crus-II. An additional fMRI study was performed to control for differences in motor output and response timing between the tasks. In this control study, the cerebellar activation sites of the rate-dependent and rate-independent color discrimination networks remained unaltered. The motor-and-detection network included cerebellar activations in posterior left Crus-I and right Crus-II, but none in lobule-V or the vermis. Thus, cerebellar activation sites of the motor-and-detection network could be subdivided into those related to a motor network and those belonging to a dimming detection network. We conclude that successive color discrimination activates multiple, functionally distinct cerebellar regions.
Laboratory of Theoretical Neurobiology, Born-Bunge Foundation, University of Antwerp-U.A., Universiteitsplein 1, B2610, Antwerpen, Belgium.
Kristl G
KG
Claeys
Guy A
GA
Orban
Patrick
P
Dupont
Stefan
S
Sunaert
Paul
P
Van Hecke
Erik
E
De Schutter
D000328:Adult; D002531:Cerebellum / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D003118:Color Perception / Q000502:physiology; D015350:Contrast Sensitivity / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D014055:Tomography, Emission-Computed; D014796:Visual Perception / Q000502:physiology*