Prefrontal Cortex Activated Bilaterally by a Tilt Board Balance Task: A Functional Near-Infrared Spectroscopy Study in a Semi-Immersive Virtual Reality Environment

Abstract

The aim of this study was to assess the prefrontal cortex (PFC) oxygenation response to a 5-min incremental tilt board balance task (ITBBT) in a semi-immersive virtual reality (VR) environment driven by a depth-sensing camera. It was hypothesized that the PFC would be bilaterally activated in response to the increase of the ITBBT difficulty, given the PFC involvement in the allocation of the attentional resources to maintain postural control. Twenty-two healthy male subjects were asked to use medial-lateral postural sways to maintain their equilibrium on a virtual tilt board (VTB) balancing over a pivot. When the subject was unable to maintain the VTB angle within ± 35° the VTB became red (error). An eight-channel fNIRS system was employed for measuring changes in PFC oxygenated-deoxygenated hemoglobin (O2Hb-HHb, respectively). Results revealed that the number of the performed board sways and errors augmented with the increasing of the ITBBT difficulty. A PFC activation was observed with a tendency to plateau for both O2Hb-HHb changes within the last 2 min of the task. A significant main effect of the level of difficulty was found in O2Hb and HHb (p < 0.001). The study has demonstrated that the oxygenation increased over the PFC while the subject was performing an ITBBT in a semi-immersive VR environment. This increase was modulated by the task difficulty, suggesting that the PFC is bilaterally involved in attention-demanding tasks. This task could be considered useful for diagnostic testing and functional neurorehabilitation given its adaptability in elderly and in patients with movement disorders.

Prefrontal cortex as a compensatory network in ataxic gait: A correlation study between cortical activity and gait parameters

“…The velcro fastener was positioned between the flexible probe holders and the black cloth. Although the subsystolic pressure induced by the velcro fastener was not adequate to induce a transient complete blockage of the skin circulation as in Takahashi's study (Takahashi et al, 2011), the pressure on the optodes was considered adequate to induce a consistent reduction of skin blood flow, if signals corresponding to the shape and size of the optodes were evident on the head skin for at least 15 minutes after the experimental section Ferrari et al, 2014). We interpreted the presence on the skin of depressed cutaneous areas as prove that the applied subsystolic pressure was able to squeeze part of the venous blood volume out of the forehead skin.…”

Review of functional near-infrared spectroscopy in neurorehabilitation

“…The prefrontal involvement in the active balance tasks was confirmed using a virtual tilt board task, which showed a positive correlation between task difficulty and prefrontal activation. 44 In addition, Mahoney et al 45 reported a larger prefrontal activation during a dual-task standing task in patients with Parkinson's disease compared with healthy subjects or patients with mild Parkinsonian signs. These findings also supported the notion that the PFC may compensate for the impaired postural ability in patients with neurological disorders.…”

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

“…Most previous studies examining postural control have employed indirect methods such as mental imagery of standing (Zwergal et al, 2012; Malouin et al, 2003; Jahn et al, 2004), virtual reality (Basso Moro et al, 2014; Ferrari et al, 2014) or even simulated active balance during supine position (Karim et al, 2014) instead of measuring activity online during actual standing. Findings from these studies employing indirect methods to assess cortical postural control suggest that the prefrontal cortex plays a critical role in healthy younger adults (Basso Moro et al, 2014; Ferrari et al, 2014) and in patients with neurological conditions like stroke (Fujimoto et al, 2014). However, in order to better understand the mechanism of postural instability in healthy older adults and in patients with PS, direct online cortical measurement in the prefrontal regions during upright standing is needed.…”