Imaging the Responding Neuronal Population with 14c-2-Deoxyglucose: The Somatosensory Cerebral Cortical Signature of a Tactile Stimulus

Abstract

The single unit method has been used to great advantage for several decades and, as a result, there exists a wealth of information about the properties of individual somatosensory neurons and their capacity to signal specific stimulus events. While single unit studies have advanced our understanding of individual somatosensory neuron behavior (e.g., response properties, input-output relations, receptive field organization, stimulus feature extraction, etc.), they have provided limited information about the spatial distribution of the population of neurons activated at a given level of the somatosensory projection pathway by a given stimulus. As a consequence, there is currently little evidence which bears directly on the possibility that population response patterns might encode important information about somatsensory stimulus conditions, or the possibility that the information encoded at the level of somatosensory neuron populations might differ from that eneoded by single neurons. A related possibility for which there also is little evidence is that the spatiotemporal population response patterns set up at cerebral cortical levels of the projection pathway (e.g., the SI or SII cortex) by somatic stimuli are decoded by higher levels (e.g., posterior parietal cortex) which process somatosensory input.