Abstract:
Positron computed tomography (CT) and 18-F fluorodeoxyglucose
(FDG) were used to measure local cerebral glucose metabolism (LCMRGlc)
in patients and normal subjects during auditory and visual stimulation
and deprivation. Sixty-six studies were performed in 42 individuals. In
normal subjects metabolic left-right symmetry was found in states of
partial (eyes patched or ears plugged) sensory deprivation. Visual
stimuli of increasing complexity produced symmetric increases in LCMRGlc
of the primary and associative visual cortices. Patients with lesions of
the visual pathway but sparing the visual cortex demonstrated
abnormalities in visual cortical LCMRGlc that correlated with clinical
symptoms. Auditory stimulation studies in normal subjects demonstrated
metabolic evidence of hemispheric specialization. The side (left versus
right) and site of maximal metabolic response correlated with the type
(verbal versus nonverbal) and content (factual story, chords, tone
sequences) of the stimulus as well as the strategy used by the subject
to solve the listening task. There was no correlation between the site
of metabolic response and side of stimulus presentation. The results of
these studies demonstrate that positron CT provides new and previously
unattainable information about local human brain physiology in normal
and pathological states. The limitations, advantages and future
prospects of using these methods to study human brain function are
discussed