Neuronal basis of optical imaging signals in sensory cortex

Abstract

The advent of non-invasive imaging methods such as functional magnetic resonance imaging (fMRI) has made it possible to obtain spatial maps of hemodynamic 'activation' in the human brain under a variety of conditions. However, the indirect and poorly understood nature of the coupling between these hemodynamic signals and the underlying neuronal activity has greatly limited the interpretability of neuroimaging results. In our laboratory, we address the question of coupling between pre- and post-synaptic neuronal activity, and the hemodynamic response in rodent somatosensory cortex in response to a localized tactile stimulus. We use full-field multiple-wavelength (spectroscopic) optical imaging of the intrinsic signals that enables simultaneous measurements of oxyhemoglobin (HbO), deoxyhemoglobin (Hb) and total hemoglobin (HbT) and simultaneous electrophysiological recordings of spiking and synaptic activity. Our results show that