BRAIN ACTIVITY PATTERNS IN FLYING, ECHOLOCATING BATS (PTERONOTUS-PARNELLII) - ASSESSMENT BY HIGH-RESOLUTION AUTORADIOGRAPHIC IMAGING WITH [H-3] 2-DEOXYGLUCOSE

Brain activity patterns during echolocation and flight were assessed i n mustached bats (Pteronotus parnellii parnellii). Bats were injected intraperitoneally with [H-3]2-deoxyglucose and restrained in a foam ho lder or allowed to fly for 20 min. Under resting conditions, low level s of [H-3]2-deoxyglucose uptake were observed throughout the forebrain but relatively high uptake was found in brainstem auditory and vestib ular centers. In flying, echolocating bats, marked increases in region al [H-3]2-deoxyglucose uptake were apparent. All structures of the cla ssical ascending auditory pathway were intensely labeled in autoradiog rams. Other brain regions that exhibited high [H-3]2-deoxyglucose upta ke in flying bats included the cingulate cortex, stratum lacunosum-mol eculare of the hippocampus, thalamus, caudate-putamen, superior collic ulus, pontine reticular formation, nucleus ambiguus, parts of the midb rain central gray, and cerebellum. In the cerebellum, the most promine nt increase in [H-3]2-deoxyglucose uptake was found in discrete patche s of the granule cell layer. The results provide the first overview of brain activity patterns during echolocation and flight in bats. In ad dition, uptake of [C-14]fluorodeoxyglucose was used to compare brain a ctivity patterns in flying bats to bats that were imaging their enviro nment via biosonar while hanging in a wire cage. The echolocating-not- flying bats emitted 6931 +/- 1226 pulses in 20 min compared to 8972 +/ - 1273 pulses in 20 min for flying bats. The uptake of the metabolic m arker was significantly more in the flying bats compared to the emitti ng-not-flying bats in the medial geniculate, superior colliculus, audi tory cortex, cingulate cortex and thalamus. In the nucleus ambiguus, c ochlear nucleus, and inferior colliculus. uptake was similar for the f lying and emitting-not-flying bats. These results suggest that the hig h metabolic activity observed in forebrain auditory regions of flying bats is related in part to neural processes that involve sensory motor integration during flight and not simply the perception of acoustic i nformation.