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Hardware architecture for real-time EEG-based functional brain connectivity parameter extraction

Hardware architecture for real-time EEG-based functional brain connectivity parameter extraction
Hardware architecture for real-time EEG-based functional brain connectivity parameter extraction

Objective. Design a novel architecture for real-time quantitative characterization of functional brain connectivity (FC) networks derived from wearable electroencephalogram (EEG). Approach. We performed an algorithm to architecture mapping for the calculation of phase lag index to form the functional connectivity networks and the extraction of a set of graph-theoretic parameters to quantitatively characterize these networks. This mapping was optimized using approximations in the mathematical definitions of the algorithms which reduce its computational complexity and produce a more hardware amenable implementation. Main results. The architecture was developed for a 19-channel EEG system. The system can calculate all the functional connectivity parameters in a total time of 131 µs, utilizes 71% of the total logic resources in the FPGA, and shows 51.84 mW dynamic power consumption at 22.16 MHz operation frequency when implemented in a Stratix IV EP4SGX230K FPGA. Our analysis also showed that the system occupies an area equivalent to approximately 937 K 2-input NAND gates, with an estimated power consumption of 39.3 mW at 0.9 V supply using a 90 nm CMOS application specific integrated circuit technology. Significance. The proposed architecture can calculate the FC and extract the graph-theoretic parameters in real-time with low power consumption. This characteristic makes the architecture ideal for applications such as a wearable closed-loop neurofeedback systems, where constant monitoring of the brain activity and fast processing of EEG is necessary to control the appropriate feedback.

EEG, FPGA, functional connectivity, graph connectivity, phase lag index, real-time processing
1741-2552
Nuno, Rafael Angel Gutierrez
0d732031-1fc9-40bf-b91f-3af547ea9b54
Chung, Chi Hang Raphael
b803c9bf-f7a2-4730-82d0-30f18a8f69ea
Maharatna, Koushik
93bef0a2-e011-4622-8c56-5447da4cd5dd
Nuno, Rafael Angel Gutierrez
0d732031-1fc9-40bf-b91f-3af547ea9b54
Chung, Chi Hang Raphael
b803c9bf-f7a2-4730-82d0-30f18a8f69ea
Maharatna, Koushik
93bef0a2-e011-4622-8c56-5447da4cd5dd

Nuno, Rafael Angel Gutierrez, Chung, Chi Hang Raphael and Maharatna, Koushik (2021) Hardware architecture for real-time EEG-based functional brain connectivity parameter extraction. Journal of Neural Engineering, 18 (3), [036012]. (doi:10.1088/1741-2552/abd462).

Record type: Article

Abstract

Objective. Design a novel architecture for real-time quantitative characterization of functional brain connectivity (FC) networks derived from wearable electroencephalogram (EEG). Approach. We performed an algorithm to architecture mapping for the calculation of phase lag index to form the functional connectivity networks and the extraction of a set of graph-theoretic parameters to quantitatively characterize these networks. This mapping was optimized using approximations in the mathematical definitions of the algorithms which reduce its computational complexity and produce a more hardware amenable implementation. Main results. The architecture was developed for a 19-channel EEG system. The system can calculate all the functional connectivity parameters in a total time of 131 µs, utilizes 71% of the total logic resources in the FPGA, and shows 51.84 mW dynamic power consumption at 22.16 MHz operation frequency when implemented in a Stratix IV EP4SGX230K FPGA. Our analysis also showed that the system occupies an area equivalent to approximately 937 K 2-input NAND gates, with an estimated power consumption of 39.3 mW at 0.9 V supply using a 90 nm CMOS application specific integrated circuit technology. Significance. The proposed architecture can calculate the FC and extract the graph-theoretic parameters in real-time with low power consumption. This characteristic makes the architecture ideal for applications such as a wearable closed-loop neurofeedback systems, where constant monitoring of the brain activity and fast processing of EEG is necessary to control the appropriate feedback.

Text
Gutierrez+Nuno+et+al_2020_J._Neural_Eng._10.1088_1741-2552_abd462 - Accepted Manuscript
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More information

Accepted/In Press date: 16 December 2020
e-pub ahead of print date: 9 March 2021
Published date: 1 June 2021
Additional Information: Publisher Copyright: © 2021 IOP Publishing Ltd.
Keywords: EEG, FPGA, functional connectivity, graph connectivity, phase lag index, real-time processing

Identifiers

Local EPrints ID: 447096
URI: http://eprints.soton.ac.uk/id/eprint/447096
ISSN: 1741-2552
PURE UUID: 626ddbf3-2093-493e-94cd-13d3df1044e1
ORCID for Rafael Angel Gutierrez Nuno: ORCID iD orcid.org/0000-0002-8226-4725

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Date deposited: 03 Mar 2021 17:31
Last modified: 17 Mar 2024 06:22

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Contributors

Author: Rafael Angel Gutierrez Nuno ORCID iD
Author: Chi Hang Raphael Chung
Author: Koushik Maharatna

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