Data 1 of 3 for: Optical coherence tomography imaging of evoked neural activity in sciatic nerve of rat
Objective: To investigate changes in intensity, phase retardation, phase, and frequency spectra obtained from optical coherence tomography (OCT) images in response to evoked neural activity in sciatic nerve of rat in vitro. Approach: M-scans with 20 μs temporal resolution were obtained on peripheral nerves of rat using a swept source polarisation sensitive optical coherence tomography (PS-OCT) system, while a nerve cuff acquired electrical neural recordings. From a total of 10 subjects: 3 had no stimulation (controls), 3 had paw stimulation, and 4 had nerve stimulation. Changes in the OCT signal intensity, phase retardation, phase, and frequency spectra were calculated for each subject and compared to the control subjects as well as reference samples of a mirror and microspheres in solution. Main results: Observed changes in phase retardation and phase were not above the noise level of reference mirror sample. Observed changes in intensity in 3 paw stimulation and 2 nerve stimulation subjects and changes in frequency spectra amplitude in 2 paw stimulation were above the reference noise level. The delayed onset and extended duration of the changes in intensity and frequency spectra amplitude were temporally consistent with osmotic swelling from potassium ion currents in myelinated fibres which has previously been characterised in squid and crab nerve using light scattering techniques but has not been reported using OCT on myelinated fibres. Significance: Imaging osmotic swelling in neural tissue using OCT signal intensity and frequency spectra creates exciting new possibilities for functional imaging in peripheral nerves and white matter of the brain.