Wavelet Transform-Based De-Noising for Two-Photon Imaging of Synaptic Ca²⁺ Transients

详细信息    查看全文

• 作者：Cezar M. Tigaret^&dagger ; ; ^{cezar.tigaret@bristol.ac.uk} ; Krasimira Tsaneva-Atanasova^&Dagger ; ; Graham L. Collingridge^&dagger ; ; Jack R. Mellor^&dagger ; ; ^{jack.mellor@bristol.ac.uk}
• 刊名：Biophysical Journal
• 出版年：2013
• 出版时间：5 March, 2013
• 年：2013
• 卷：104
• 期：5
• 页码：1006-1017
• 全文大小：1450 K

文摘

Postsynaptic Ca²⁺ transients triggered by neurotransmission at excitatory synapses are a key signaling step for?the induction of synaptic plasticity and are typically recorded in tissue slices using two-photon fluorescence imaging with Ca²⁺-sensitive dyes. The signals generated are small with very low peak signal/noise ratios (pSNRs) that make detailed analysis problematic. Here, we implement a wavelet-based de-noising algorithm (PURE-LET) to enhance signal/noise ratio for Ca²⁺ fluorescence transients evoked by single synaptic events under physiological conditions. Using simulated Ca²⁺ transients with defined noise levels, we analyzed the ability of the PURE-LET algorithm to retrieve the underlying signal. Fitting single Ca²⁺ transients with an exponential rise and decay model revealed a distortion of ¦Ó_rise but improved accuracy and reliability of ¦Ó_decay and peak amplitude after PURE-LET de-noising compared to raw signals. The PURE-LET de-noising algorithm also provided a ¡«30-dB gain in pSNR compared to ¡«16-dB pSNR gain after an optimized binomial filter. The higher pSNR provided by PURE-LET de-noising increased discrimination accuracy between successes and failures of synaptic transmission as measured by the occurrence of synaptic Ca²⁺ transients by ¡«20 % relative to an optimized binomial filter. Furthermore, in comparison to binomial filter, no optimization of PURE-LET de-noising was required for reducing arbitrary bias. In conclusion, the de-noising of fluorescent Ca²⁺ transients using PURE-LET enhances detection and characterization of Ca²⁺ responses at central excitatory synapses.