The role of prefrontal cortex during postural control in Parkinsonian syndromes a functional near-infrared spectroscopy study

Abstract

Postural instability represents a main source of disability in Parkinsonian syndromes and its pathophysiology is poorly understood. Indirect probes (i.e., mental imagery) of brain involvement support the role of prefrontal cortex as a key cortical region for postural control in older adults with and without Parkinsonian syndromes. Using functional near infrared spectroscopy (fNIRs) as a direct online cortical probe, this study aimed to compare neural activation patterns in prefrontal cortex, postural stability, and their respective interactions, in (1) patients with Parkinsonian syndromes; (2) those with mild parkinsonian signs; (3) and healthy older adults. Among 269 nondemented older adults (76.41±6.70 years, 56% women), 26 individuals presented with Parkinsonian syndromes (Unified Parkinson's disease rating scale (UPDRS): 11.08±3.60), 117 had mild parkinsonian signs (UPDRS: 3.21±2.49), and 126 individuals were included as a healthy control group. Participants were asked to stand upright and count silently for ten seconds while changes in oxygenated hemoglobin levels over prefrontal cortex were measured using fNIRs. We simultaneously evaluated postural stability with center of pressure velocity data recorded on an instrumented walkway. Compared to healthy controls and patients with mild parkinsonian signs, patients with Parkinsonian syndromes demonstrated significantly higher prefrontal oxygenation levels to maintain postural stability. The pattern of brain activation and postural control of participants with mild parkinsonian signs were similar to that of normal controls. These findings highlight the online role of the prefrontal cortex in postural control in patients with Parkinsonian syndromes and afford the opportunity to improve therapeutic options for postural instability.

Cognitive Remediation to Enhance Mobility in Older Adults: the Crem Study

“…In subsequent fNIRS studies, we have demonstrated that internal consistency of HbO 2 measurements, determined by split-half intraclass correlations, was excellent for NPW (0.830) and WWT (0.849) [39]. Furthermore, we have replicated the original finding demonstrating increased activation levels in the PFC in WWT compared with NPW in a large cohort of older adults [39], elucidated the role of the PFC in cognitive control of attentiondemanding locomotion in groups stratified by the presence of peripheral and central gait abnormalities [45] and reported on the effect of mild Parkinsonian symptoms on the involvement of the PFC in balance [46].…”

Optical windows for head tissues in near‐infrared and short‐wave infrared regions: Approaching transcranial light applications

“…Availability of these peaks makes the extended SWIR region advantageous for optical spectroscopy of biological tissues . Spectroscopy techniques has been applied to brain or bone tissues, allowing for identification and monitoring of tissue endogenous constituents (eg, lipids) in SWIR and SWIR‐II windows . It can be assumed that this approach can be extended to the spectral imaging, aiming at the localization and visualization of the tissue constituents in situ.…”

Stress and gender effects on prefrontal cortex oxygenation levels assessed during single and dual‐task walking conditions

“…Proximal baseline conditions ranging from 5–15 s have been previously reported in fNIRS studies (Izzetoglu et al ., ). Consistent with our prior studies (Holtzer et al ., , ,b; Mahoney et al ., ) separate proximal 10‐s baselines, administered prior to each experimental condition, were used to determine relative changes of HbO 2 concentrations in NW, Alpha and WWT conditions.…”