A portable and low-cost fMRI compatible pneumatic system for the investigation of the somatosensensory system in clinical and research environments

Abstract

There still is a need for devices that allow reproducible stimulation of skin areas of the human body. We constructed a stimulation system and tested it by using brief pneumatic stimulation to the right thumb of nine healthy volunteers. BOLD-signals in response to tactile stimulation with frequencies of 1, 3 and 5 Hz were measured using a 3 T MRI scanner. The stimulation device consists of synthetic membranes connected to plastic tubes capable of carrying compressed air, and an electronic component, which controls the on-and off-switching of an electromagnetic valve. The valve near the MR-scanner did not lower the image quality. Primary somatosensory activation contralateral to the stimulation site was reliably detected in response to a stimulus magnitude of 3.5 bar in all volunteers. 1 Hz stimulation resulted in higher maximal percentage BOLD-signal changes. Our device is an easy-to-construct, low-cost and portable tool suitable for research and clinical environments. It permits passive non-painful stimulation relevant for clinical assessments and is also compatible with magnetoencephalography (MEG) and electroencephalography (EEG). In basic and clinical research, this device therefore contributes to meaningful comparisons between results obtained with different techniques.

Long-term sensory stimulation therapy improves hand function and restores cortical responsiveness in patients with chronic cerebral lesions. Three single case studies

“…We choose pneumatic stimulation as it has been shown that this form of fingertip stimulation activates the human primary sensory cortex (Elbert et al, 1995; Candia et al, 2003), while electrical stimulation activates afferent fibers (Hashimoto et al, 2004). Stimulation was conducted as described by Wienbruch and colleagues (2006). Non-painful stimuli of 50 ms duration, with a frequency of 1.5 Hz were applied to finger clips with flexible membranes placed on each finger segment of d2 and d5.…”

“…The incoming airflow drives a circular synthetic membrane of approximately 0.8 cm 2 (4D Neuroimaging Inc., San Diego, USA) through plastic standard tubes (PUN-4×0,75-SI; outside diameter 4 mm, inside diameter 2.6 mm and PUN-3×0,5-SI; outside diameter 3 mm, inside diameter 2.1 mm; copper and Teflon-free for QS push-in fittings, Festo®) [cf. (Wienbruch et al, 2006)]. During measurements subjects were instructed to concentrate on the stimulus.…”

“…For the assessment of functional hand motor skills we used subtests from the Jebsen-Taylor Hand Function Test. Additionally, in one subject the possible impact of repetitive stimulation on brain organization was investigated by recording tactile-stimulation evoked somatosensory evoked potentials (SEP) using high-density EEG (Montoya and Sitges, 2006; Wienbruch et al, 2006). The purpose of the single case studies was to determine the effects of long-term rSS on the sensorimotor performance of patients with chronic CL who were considered resistant to any further standard therapy.…”

Rapid cortical reorganisation and improved sensitivity of the hand following cutaneous anaesthesia of the forearm

“…The study subjects were asked to lie still with their eyes closed and the head was stabilised with cushions and foam pads during the experiment. The stimuli system was pneumatically driven and electronically controlled, based on the same principle as that presented by Wienbruch et al. (2006).…”

Somatosensory Stimulation in Functional Neuroimaging: A Review

“…Higher stimulation frequencies can be achieved by using nonmagnetic valves, suited for operation inside the MR scanner room. Multi-channel stimulation designs are feasible with multiple valves and pickups (Wienbruch et al, 2006). Pneumatic devices have shown to cause somatosensory brain activation, but failed to additionally activate motor cortical areas in somatosensory paradigms.…”