Functional near infra-red spectroscopy during walking in young, old and Parkinson’s disease: a structured review Rodrigo Vitorio1,2, Samuel Stuart1, Lynn Rochester1, Annette Pantall1, Lisa Alcock1 1Institute 2Posture
of Neuroscience/Newcastle University Institute of Ageing, Newcastle University, UK
and Gait Studies Laboratory, Institute of Biosciences, Sao Paulo State University (UNESP), Brazil
http://research.ncl.ac.uk/bam |
Introduction
@BAM_Research
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Results
Recommendations
• The use of functional near infra-red spectroscopy (fNIRS) to investigate cortical activity during walking is emerging and may provide information regarding the neural correlates of mobility impairments caused by ageing and Parkinson’s disease (PD).
• The search strategy yielded 172 articles from publication databases and seven additional articles were identified by screening reference lists. Thirty-one studies satisfied the criteria for inclusion (Fig 1).
• However, there is a need for standardizing methodological procedures. None has assessed how different protocols relate to conflicting findings.
• The cumulative frequency of the reviewed studies have increased exponentially in the last four years (Fig 2).
number of papers published
35
Aims: 1) To evaluate fNIRS walking study design in young adults, older adults and people with PD; 2) To examine signal processing techniques to reduce artefacts and physiological noise in fNIRS data; and 3) To provide evidence-based recommendations for fNIRS walking study design and signal analysis techniques.
• Four electronic databases were searched (Embase, Psych-Info, Scopus and PubMed). Search request consisted of four search fields; 1) measurement technique of interest to evaluate cortical activity, 2) synonyms for populations of interest (i.e. only studies that tested healthy young adults, healthy old adults or people with PD were included), 3) synonyms for walking tasks, and 4) synonyms for dual (cognitive and/or motor) tasks. • Articles were included if they reported the use of fNIRS during an active walking task (e.g. usual walking, dual task, obstacle crossing etc.). • Data was extracted by three reviewers (RV, SS, LA) and synthesised into table format and data entry was confirmed by another reviewer (AP).
• Data reviewed included: study design and protocol; dual task protocol; fNIRS devices; data outcomes; signal processing; and key findings.
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• Perform baseline correction trials before every trial to account for time-dependent changes in cerebral oxygenation. • Employ standardised block design protocols to control for time dependent effects relating to stimulus/experimental manipulation (for example asking a participant to walk for a set period rather than a given distance). This reduces need for retrospective signal processing (e.g. to normalise the signal length) avoiding signal distortion.
• Allow for the 4-7 second delay in haemodynamic peak response by including sufficiently long walks (/periods of exposure).
20 15 10
7
5 1
2
• Report all steps of signal processing, including filtering and noise removal, and study specific processing or analysis.
0
• Develop cognitive tasks with levels of difficulty that introduce minimal artefact.
Period
Fig 1 Flow chart with information through the different phases of the search process
Methods
31
• Sample sizes should be sufficiently large and justified by power analyses.
Fig 2 Cumulative number of research papers published per year using fNIRS to record brain cortical activity during walking in healthy adults and people with PD
• Most studies involved small sample sizes (15 studies with n
