MRI-compatible pneumatic stimulator for sensorimotor mapping

Abstract

Background: Two major concerns with respect to task-based motor functional magnetic resonance imaging (fMRI) are inadequate participants' performance as well as intra-and inter-subject variability in execution of the motor action. New method: This study validates the use of an MRI-compatible stimulator based on a pneumatic artificial muscle (PAM) for block-design fMRI mapping of the primary sensorimotor (SM1) cortex in a series of fifteen right-handed healthy subjects. The PAM stimulator elicits computer-controlled timely and reproducible passive movements of fingers/toes. Participants performed comparable active and passive PAM-induced flexion-extensions of the index fingers. Results: Passive movement of the right index finger and passive alternating right and left index finger movement resulted in a significant increase in blood-oxygen-level-dependent (BOLD) signal in contralateral SM1 cortex in 14/15 and 15/15 subjects respectively. Similar networks were recruited by active and passive index finger movements. However, at the group level, active movement induced significantly higher increases in BOLD signal than passive movement in contralateral SM1 cortex (p < 0.05 Family Wise Error [FWE] corrected), supplementary motor area (p < 0.001 uncorrected), ipsilateral cerebellum (p < 0.001 uncorrected), and bilateral putamina (p < 0.001 uncorrected). Comparison with existing method(s): As compared to the several MRI-compatible robotic devices for computercontrolled passive movement of the fingers that were introduced in the past decades, the proposed PAM-based stimulator is smaller, handier, and easier to use in the MRI setting. Conclusions: PAM-based stimulators can be reliably used for passive sensorimotor fMRI mapping in healthy subjects. Using this approach, bilateral SM1 cortices can be mapped accurately during a single 6-min blockdesign fMRI protocol.

Coupling between human brain activity and body movements: Insights from non-invasive electromagnetic recordings

“…CKC has also been observed during passive movements of the fingers and toes either produced by an investigator or an MEG-compatible device based on elastic "pneumatic artificial muscles" (PAM) (Bourguignon et al, 2015;Piitulainen et al, 2013b). For more details about the PAM stimulator that predominantly elicits proprioceptive pathways stimulation, see Lolli et al (2019) and Piitulainen et al (2015b). The main findings of these studies were that repetitive passive movements led to strong CKC (coherence levels up to 0.8) with underlying sources located in a somatotopic manner at the contralateral SM1 hand or foot areas.…”

Stronger proprioceptive BOLD-responses in the somatosensory cortices reflect worse sensorimotor function in adolescents with and without cerebral palsy

“…Cortical proprioception can be studied using passive naturalistic movements of specific joints using different brain imaging methods ( Müller-Putz et al, 2007 , Sasaki et al, 2017 , Sasaki et al, 2018 , Alary et al, 2002 , Druschky et al, 2003 , Lange et al, 2001 , Lolli et al, 2019 , Nurmi et al, 2018 , Piitulainen et al, 2015 , Piitulainen et al, 2018 , Piitulainen et al, 2021 , Seiss et al, 2002 , Vallinoja et al, 2021 ). For the continuous index finger movement, strongest BOLD-fMRI responses have been shown to be elicited by 3–6 Hz movements when using a blocked design ( Nurmi et al, 2018 ).…”

Pneumatic artificial muscle-based stimulator for passive functional magnetic resonance imaging sensorimotor mapping in patients with brain tumours

“…Previous positron emission tomography (PET) and fMRI studies have demonstrated that both contralateral primary somatosensory (S1) and motor (M1) cortices display significant increases in regional cerebral blood flow or BOLD fMRI signal during passive movements, with very similar activation patterns as compared to active motion (Weiller et al, 1996;Reddy et al, 2001;Guzzetta et al, 2007;Kocak et al, 2009;Boscolo Galazzo et al, 2014;Choudri et al, 2015;Lolli et al, 2019). Therefore, it has been suggested to generate movements passively to overcome potential limitations related to active motor task performance.…”

“…Pneumatic artificial muscles (PAMs) are elastic actuators that vary in length with changing internal air pressure. Non-magnetic stimulators based on PAMs have been developed to investigate human neuromagnetic activity elicited by passive movements of fingers or toes in the magnetoencephalography (MEG) or fMRI environment (Piitulainen et al, 2015;Nurmi et al, 2018;Lolli et al, 2019;Piitulainen et al, 2020;Vallinoja et al, 2021). PAM-based stimulators seem of particular interest in the neuroimaging setting as they appear to smaller and easier to use than the robotic devices previously described.…”

“…The PAM-based stimulator used in our study has proven to accurately map the SM1 cortex contralateral to finger movement in a series of fifteen healthy adults who underwent both analogous active and passive PAM-induced flexion-extensions of the index fingers (Lolli et al, 2019).…”