James B Fallon1, Sam Irving2, Satinderpall S Pannu3, Angela C Tooker3, Andrew K Wise4, Robert K Shepherd5, Dexter R F Irvine2. 1. Bionics Institute, Melbourne, Victoria, Australia; Department of Otolaryngology, University of Melbourne, Melbourne, Victoria, Australia; Medical Bionics Department, University of Melbourne, Melbourne, Victoria, Australia. Electronic address: jfallon@bionicsinstitute.org. 2. Bionics Institute, Melbourne, Victoria, Australia. 3. Lawrence Livermore National Laboratory, Livermore, CA, United States. 4. Bionics Institute, Melbourne, Victoria, Australia; Department of Otolaryngology, University of Melbourne, Melbourne, Victoria, Australia; Medical Bionics Department, University of Melbourne, Melbourne, Victoria, Australia. 5. Bionics Institute, Melbourne, Victoria, Australia; Medical Bionics Department, University of Melbourne, Melbourne, Victoria, Australia.
Abstract
BACKGROUND: Current source density analysis of recordings from penetrating electrode arrays has traditionally been used to examine the layer- specific cortical activation and plastic changes associated with changed afferent input. We report on a related analysis, the second spatial derivative (SSD) of surface local field potentials (LFPs) recorded using custom designed thin-film polyimide substrate arrays. RESULTS: SSD analysis of tone- evoked LFPs generated from the auditory cortex under the recording array demonstrated a stereotypical single local minimum, often flanked by maxima on both the caudal and rostral sides. In contrast, tone-pips at frequencies not represented in the region under the array, but known (on the basis of normal tonotopic organization) to be represented caudal to the recording array, had a more complex pattern of many sources and sinks. COMPARISON WITH EXISTING METHODS: Compared to traditional analysis of LFPs, SSD analysis produced a tonotopic map that was more similar to that obtained with multi-unit recordings in a normal-hearing animal. Additionally, the statistically significant decrease in the number of acoustically responsive cortical locations in partially deafened cats following 6 months of cochlear implant use compared to unstimulated cases observed with multi-unit data (p=0.04) was also observed with SSD analysis (p=0.02), but was not apparent using traditional analysis of LFPs (p=0.6). CONCLUSIONS: SSD analysis of surface LFPs from the thin-film array provides a rapid and robust method for examining the spatial distribution of cortical activity with improved spatial resolution compared to more traditional LFP recordings.
BACKGROUND: Current source density analysis of recordings from penetrating electrode arrays has traditionally been used to examine the layer- specific cortical activation and plastic changes associated with changed afferent input. We report on a related analysis, the second spatial derivative (SSD) of surface local field potentials (LFPs) recorded using custom designed thin-film polyimide substrate arrays. RESULTS: SSD analysis of tone- evoked LFPs generated from the auditory cortex under the recording array demonstrated a stereotypical single local minimum, often flanked by maxima on both the caudal and rostral sides. In contrast, tone-pips at frequencies not represented in the region under the array, but known (on the basis of normal tonotopic organization) to be represented caudal to the recording array, had a more complex pattern of many sources and sinks. COMPARISON WITH EXISTING METHODS: Compared to traditional analysis of LFPs, SSD analysis produced a tonotopic map that was more similar to that obtained with multi-unit recordings in a normal-hearing animal. Additionally, the statistically significant decrease in the number of acoustically responsive cortical locations in partially deafened cats following 6 months of cochlear implant use compared to unstimulated cases observed with multi-unit data (p=0.04) was also observed with SSD analysis (p=0.02), but was not apparent using traditional analysis of LFPs (p=0.6). CONCLUSIONS: SSD analysis of surface LFPs from the thin-film array provides a rapid and robust method for examining the spatial distribution of cortical activity with improved spatial resolution compared to more traditional LFP recordings.
Authors: Andrej Kral; Jochen Tillein; Peter Hubka; Dorrit Schiemann; Silvia Heid; Rainer Hartmann; Andreas Karl Engel Journal: J Neurosci Date: 2009-01-21 Impact factor: 6.167
Authors: Fei Peng; Hamish Innes-Brown; Colette M McKay; James B Fallon; Yi Zhou; Xing Wang; Ning Hu; Wensheng Hou Journal: Front Neural Circuits Date: 2018-07-24 Impact factor: 3.492