Detection of axonal synapses in 3D two-photon images.

Studies of structural plasticity in the brain often require the detection and analysis of axonal synapses (boutons). To date, bouton detection has been largely manual or semi-automated, relying on a step that traces the axons before detection the boutons. If tracing the axon fails, the accuracy of b...

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Main Authors: Cher Bass, Pyry Helkkula, Vincenzo De Paola, Claudia Clopath, Anil Anthony Bharath
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2017-01-01
Series:PLoS ONE
Online Access:https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0183309&type=printable
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author Cher Bass
Pyry Helkkula
Vincenzo De Paola
Claudia Clopath
Anil Anthony Bharath
author_facet Cher Bass
Pyry Helkkula
Vincenzo De Paola
Claudia Clopath
Anil Anthony Bharath
author_sort Cher Bass
collection DOAJ
description Studies of structural plasticity in the brain often require the detection and analysis of axonal synapses (boutons). To date, bouton detection has been largely manual or semi-automated, relying on a step that traces the axons before detection the boutons. If tracing the axon fails, the accuracy of bouton detection is compromised. In this paper, we propose a new algorithm that does not require tracing the axon to detect axonal boutons in 3D two-photon images taken from the mouse cortex. To find the most appropriate techniques for this task, we compared several well-known algorithms for interest point detection and feature descriptor generation. The final algorithm proposed has the following main steps: (1) a Laplacian of Gaussian (LoG) based feature enhancement module to accentuate the appearance of boutons; (2) a Speeded Up Robust Features (SURF) interest point detector to find candidate locations for feature extraction; (3) non-maximum suppression to eliminate candidates that were detected more than once in the same local region; (4) generation of feature descriptors based on Gabor filters; (5) a Support Vector Machine (SVM) classifier, trained on features from labelled data, and was used to distinguish between bouton and non-bouton candidates. We found that our method achieved a Recall of 95%, Precision of 76%, and F1 score of 84% within a new dataset that we make available for accessing bouton detection. On average, Recall and F1 score were significantly better than the current state-of-the-art method, while Precision was not significantly different. In conclusion, in this article we demonstrate that our approach, which is independent of axon tracing, can detect boutons to a high level of accuracy, and improves on the detection performance of existing approaches. The data and code (with an easy to use GUI) used in this article are available from open source repositories.
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spelling doaj-art-ab8ea3e3a8304fd8b8b14c97786d310e2025-08-20T02:03:55ZengPublic Library of Science (PLoS)PLoS ONE1932-62032017-01-01129e018330910.1371/journal.pone.0183309Detection of axonal synapses in 3D two-photon images.Cher BassPyry HelkkulaVincenzo De PaolaClaudia ClopathAnil Anthony BharathStudies of structural plasticity in the brain often require the detection and analysis of axonal synapses (boutons). To date, bouton detection has been largely manual or semi-automated, relying on a step that traces the axons before detection the boutons. If tracing the axon fails, the accuracy of bouton detection is compromised. In this paper, we propose a new algorithm that does not require tracing the axon to detect axonal boutons in 3D two-photon images taken from the mouse cortex. To find the most appropriate techniques for this task, we compared several well-known algorithms for interest point detection and feature descriptor generation. The final algorithm proposed has the following main steps: (1) a Laplacian of Gaussian (LoG) based feature enhancement module to accentuate the appearance of boutons; (2) a Speeded Up Robust Features (SURF) interest point detector to find candidate locations for feature extraction; (3) non-maximum suppression to eliminate candidates that were detected more than once in the same local region; (4) generation of feature descriptors based on Gabor filters; (5) a Support Vector Machine (SVM) classifier, trained on features from labelled data, and was used to distinguish between bouton and non-bouton candidates. We found that our method achieved a Recall of 95%, Precision of 76%, and F1 score of 84% within a new dataset that we make available for accessing bouton detection. On average, Recall and F1 score were significantly better than the current state-of-the-art method, while Precision was not significantly different. In conclusion, in this article we demonstrate that our approach, which is independent of axon tracing, can detect boutons to a high level of accuracy, and improves on the detection performance of existing approaches. The data and code (with an easy to use GUI) used in this article are available from open source repositories.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0183309&type=printable
spellingShingle Cher Bass
Pyry Helkkula
Vincenzo De Paola
Claudia Clopath
Anil Anthony Bharath
Detection of axonal synapses in 3D two-photon images.
PLoS ONE
title Detection of axonal synapses in 3D two-photon images.
title_full Detection of axonal synapses in 3D two-photon images.
title_fullStr Detection of axonal synapses in 3D two-photon images.
title_full_unstemmed Detection of axonal synapses in 3D two-photon images.
title_short Detection of axonal synapses in 3D two-photon images.
title_sort detection of axonal synapses in 3d two photon images
url https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0183309&type=printable
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AT vincenzodepaola detectionofaxonalsynapsesin3dtwophotonimages
AT claudiaclopath detectionofaxonalsynapsesin3dtwophotonimages
AT anilanthonybharath detectionofaxonalsynapsesin3dtwophotonimages