Functional activation in the auditory system of the rat produced by arousing reticular stimulation: a 2-deoxyglucose study.
The 2-deoxyglucose (2-DG) autoradiographic method was used to map the activity in the auditory pathway during behaviorally arousing electrical stimulation of the mesencephalic reticular formation (RET). Uptake of 2-DG during RET stimulation was compared to the effect of a frequency-modulated tone (4-5 kHz, 60 dB SPL) and to controls without stimulation. The major finding was a specific pattern of increased metabolic activation throughout the auditory pathway evoked during RET stimulation. The observed increases in 2-DG uptake were always greater in RET-stimulated rats as compared to sound-stimulated or control rats. The dorsal cochlear nucleus (DCN) showed the largest incorporation of 2-DG among the auditory nuclei of the brainstem in RET-stimulated rats. In the central nucleus of the inferior colliculus a layered pattern made of 3 discrete bands of high 2-DG uptake was visible in RET-stimulated rats. The medial geniculate (MG) and the auditory cortex (AC) also showed highly significant increases in 2-DG uptake induced by RET stimulation. The method provided correlations between classical morphological schemes of parcellation on nuclei and functionally defined areas of increased 2-DG uptake. Our observations represent the first anatomical demonstration of the activating effects of RET stimulation in a sensory system, and they support the concepts of arousing reticular mechanisms for sensory control.
D000818:Animals; D001143:Arousal / Q000502:physiology*; D001303:Auditory Cortex / Q000378:metabolism; D001306:Auditory Pathways / Q000378:metabolism*; D001307:Auditory Perception / Q000502:physiology; D001931:Brain Mapping; D001933:Brain Stem / Q000378:metabolism; D003056:Cochlear Nerve / Q000378:metabolism; D004558:Electric Stimulation; D005829:Geniculate Bodies / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D007245:Inferior Colliculi / Q000378:metabolism; D008297:Male; D008636:Mesencephalon / Q000502:physiology*; D051381:Rats; D012154:Reticular Formation / Q000502:physiology*
D005947:Glucose