Studying the neural bases of prism adaptation using fMRI: A technical and design challenge

Abstract

Prism adaptation induces rapid recalibration of visuomotor coordination. The neural mechanisms of prism adaptation have come under scrutiny since the observations that the technique can alleviate hemispatial neglect following stroke, and can alter spatial cognition in healthy controls. Relative to non-imaging behavioral studies, fMRI investigations of prism adaptation face several challenges arising from the confined physical environment of the scanner and the supine position of the participants. Any researcher who wishes to administer prism adaptation in an fMRI environment must adjust their procedures enough to enable the experiment to be performed, but not so much that the behavioral task departs too much from true prism adaptation. Furthermore, the specific temporal dynamics of behavioral components of prism adaptation present additional challenges for measuring their neural correlates. We developed a system for measuring the key features of prism adaptation behavior within an fMRI environment. To validate our configuration, we present behavioral (pointing) and head movement data from 11 righthemisphere lesioned patients and 17 older controls who underwent sham and real prism adaptation in an MRI scanner. Most participants could adapt to prismatic displacement with minimal head movements, and the procedure was well tolerated. We propose recommendations for fMRI studies of prism adaptation based on the design-specific constraints and our results.

Sensorimotor cortex forms prism adaptation memories in older adults and stroke patients

“…As summarised by Panico et al (2019), only a small number of fMRI studies of prism adaptation have been performed (Clower et al, 1996, Danckert et al, 2008, Luauté et al, 2009, Chapman et al, 2010, Küper et al, 2014, Saj et al, 2013, 2019). In part, this is due to technical and design challenges, such as arm movement related artifacts (Bultitude et al, 2016). Studies to date have primarily focused on the initial phase of prism adaptation, which is dominated by strategic error correction (Clower et al, 1996, Danckert et al, 2008, Luauté et al, 2009), for example, by contrasting brain activity during the first few pointing trials with the last few trials.…”

“…Description of the study apparatus construction and evaluation, participant samples, MRI acquisition, and initial behavioural results are published else-where (Bultitude et al, 2016).…”

“…The model was fitted using a least squares procedure with the fmincon function in MATLAB (The MathWorks inc., version 2014b). Because of the MRI scanning environment, obtaining a reliable measure of endpoint errors posed a challenge, particularly for stroke patients (Bultitude et al, 2016). As a result, individual behavioural datasets were noisier than those typically collected outside the scanner.…”

“…Healthy individuals and stroke patients performed prism adaptation during fMRI (Bultitude et al, 2016). Using a similar approach to Kim et al (2015), a computational model was fitted to prism adaptation behaviour to extract time-varying regressors of brain activity that follow a fast or slow time-scale (Petitet et al, 2018).…”

Modifying and evaluating efficacy of interactive computerized program using motion tracking technology to improve unilateral neglect in patients with chronic stroke

“…[ 9 ] To understand the mechanism of prism adaptation, a few studies have started to use the neurophysiologic methods such as event-related potentials (ERPs) based on electroencephalography (EEG) and a functional imaging study such as fMRI. [ 10 , 11 ] However, these studies are still on the way to develop the methodology to understand the mechanism. Mechanism of mirror therapy for neglect is not clear yet.…”