Multiphoton minimal inertia scanning for fast acquisition of neural activity signals

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Title: Multiphoton minimal inertia scanning for fast acquisition of neural activity signals
Authors: Schuck, R
Go, MA
Garasto, S
Reynolds, S
Dragotti, PL
Schultz, SR
Item Type: Journal Article
Abstract: Objective: Multi-photon laser scanning microscopy provides a powerful tool for monitoring the spatiotemporal dynamics of neural circuit activity. It is, however, intrinsically a point scanning technique. Standard raster scanning enables imaging at subcellular resolution; however, acquisition rates are limited by the size of the field of view to be scanned. Recently developed scanning strategies such as Travelling Salesman Scanning (TSS) have been developed to maximize cellular sampling rate by scanning only select regions in the field of view corresponding to locations of interest such as somata. However, such strategies are not optimized for the mechanical properties of galvanometric scanners. We thus aimed to develop a new scanning algorithm which produces minimal inertia trajectories, and compare its performance with existing scanning algorithms. Approach: We describe here the Adaptive Spiral Scanning (SSA) algorithm, which fits a set of near-circular trajectories to the cellular distribution to avoid inertial drifts of galvanometer position. We compare its performance to raster scanning and TSS in terms of cellular sampling frequency and signal-to-noise ratio (SNR). Main Results: Using surrogate neuron spatial position data, we show that SSA acquisition rates are an order of magnitude higher than those for raster scanning and generally exceed those achieved by TSS for neural densities comparable with those found in the cortex. We show that this result also holds true for in vitro hippocampal mouse brain slices bath loaded with the synthetic calcium dye Cal-520 AM. The ability of TSS to "park" the laser on each neuron along the scanning trajectory, however, enables higher SNR than SSA when all targets are precisely scanned. Raster scanning has the highest SNR but at a substantial cost in number of cells scanned. To understand the impact of sampling rate and SNR on functional calcium imaging, we used the Crame ́r-Rao Bound on evoked calcium traces recorded simultaneously with electrophysiology traces to calculate the lower bound estimate of the spike timing occurrence. Significance: The results show that TSS and SSA achieve comparable accuracy in spike time estimates compared to raster scanning, despite lower SNR. SSA is an easily implementable way for standard multi-photon laser scanning systems to gain temporal precision in the detection of action potentials while scanning hundreds of active cells.
Issue Date: 1-Feb-2018
Date of Acceptance: 8-Nov-2017
ISSN: 1741-2552
Publisher: IOP Publishing
Journal / Book Title: Journal of Neural Engineering
Volume: 15
Issue: 2
Copyright Statement: © 2018 IOP Publishing Ltd. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Sponsor/Funder: The Royal Society
Biotechnology and Biological Sciences Research Council (BBSRC)
Commission of the European Communities
Funder's Grant Number: IF110059
Keywords: 0903 Biomedical Engineering
1103 Clinical Sciences
1109 Neurosciences
Biomedical Engineering
Publication Status: Published
Article Number: ARTN 025003
Appears in Collections:Faculty of Engineering
Electrical and Electronic Engineering

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