Optical coherence tomography for cross-sectional imaging of neural activity

Abstract

Abstract. We report a functional optical coherence tomography cross-sectional scanner to detect neural activity using unmyelinated nerves dissected from squid. The nerves, unstained or stained with a voltage-sensitive dye, were imaged in a nerve chamber. Transient phase changes from backscattered light were detected during action potential propagation. The results show that the scanner can provide high spatiotemporal resolution crosssectional images of neural activity (15 μs∕A-line; 0.25 ms∕B-scan; ∼8.5 × 5.5 μm 2 in xz). The advantage of this method compared to monitoring a single depth profile z is a dramatic increase in the number of available sites that can be measured in two spatial dimensions xz with lateral scanning; therefore, the study demonstrates that two-dimensional monitoring of small-scale functional activity would also be feasible.

Optical Coherence Tomography: Basic Concepts and Applications in Neuroscience Research

“…These intrinsic optical signals can be observed with optical methods such as Doppler flowmetry (LDF), near-infrared (NIR) spectrometer, functional optical coherence tomography (fOCT), and surface plasmon resonance (SPR) [ 59 ]. However, intrinsic optical signals are very small most often, which has entailed the use of molecular probes [ 62 ]. Consequently, fast voltage-sensitive dyes are being widely used to enhance the signal-to-noise ratio (SNR).…”

“…Consequently, fast voltage-sensitive dyes are being widely used to enhance the signal-to-noise ratio (SNR). For this reason, though OCT can render label-free imaging of neural activity [ 39 , 60 , 62 ], voltage-sensitive dyes are also used in most cases.…”

Nanosensitive optical coherence tomography to assess wound healing within the cornea

“…One of them is based on phase sensitive OCT (psOCT) which uses the Fourier analysis of phase differences of acquired interference spectra ( A-scans) at particular depth positions [8]. Nanoscale detection with phase sensitive techniques has been used for different applications, including optical coherence elastography (OCE) to detect the biomechanical properties [9] , to determine the submicron movement of the basilar membrane within the organ of Corti and neural action potential in a squid and others [10,11]. However, phase sensitive OCT requires two or more frames (M-scan) for realization and is inherently prone to noises (bulk motion, vibrations, etc.).…”

OCT intensity and phase fluctuations correlated with activity-dependent neuronal calcium dynamics in the Drosophila CNS [Invited]

“…Changes in OCT intensity related to neural activity have been demonstrated in both the retina [23-30] and brain [31][32][33][34][35][36][37][38]. Phase-resolved OCT has also been used to detect transient nanometer-level changes in neuronal thickness during action potential propagation in isolated nerves [39][40][41][42][43][44].…”