抄録
To investigate the effect of hypercapnia on the neural and hemodynamic responses, we measured broad band electrophysiological signals (local field potentials, LFP < 100 Hz; multiunit activity, MUA > 300 Hz), optical intrinsic signals (586 and 605 nm, indicators of CBV and oxygenation), spectral changes in reflected light (400-900 nm) and laser-Doppler blood flow. Rats were anesthetized with alpha-chloralose and artificially ventilated with muscle relaxants. Hypercapnic challenge was performed by 5% and 10% CO2 inhalation. We recorded these signals while delivering 2-s electrical pulses to the hindpaw. We observed decreases in both neural (LFP, MUA) and hemodynamic (CBF, CBV) responses, and prolonged deoxyhemoglobin increases in the early phase with attenuation of deoxyhemoglobin decreases in the late phase (i.e., disruption of hyperoxygenation responses), compared with those responses during normocapnia. These results suggested that imaging of early dip optical intrinsic signals and positive BOLD fMRI signals might not accurately reflect neural responses in strength and space domains during hypercapnia. [J Physiol Sci. 2007;57 Suppl:S245]
