Do Motor Imagery Performances Depend on the Side of the Lesion at the Acute Stage of Stroke?

What a pile of gobbledegook explaining something that should be quite simple. The writer should never be assigned to write again, and the senior advisor should not get any more research grants. You didn't answer the question, at least not to this stroke-addled person. Who the fuck are you writing this for? Even Stephan Hawking couldn't comprehend this.
http://journal.frontiersin.org/article/10.3389/fnhum.2016.00321/full?

Claire Kemlin^1,2,3,4,5*, Eric Moulton^3,4,5, Yves Samson^1,3,4,6 and Charlotte Rosso^1,3,4,5

• ¹APHP, Urgences Cérébro-Vasculaires, Hôpital Pitié-Salpêtrière, Paris, France
• ²APHP, Service de Médecine Physique et Réadaptation, Hôpital Pitié-Salpêtrière, Paris, France
• ³Centre de Recherche de l’Institut du Cerveau et de la Moelle épinière, Paris, France
• ⁴UPMC Paris 6, INSERM, U1127; CNRS, UMR 7225, Paris, France
• ⁵CONAM, UPMC Paris 6, INSERM, U1127, CNRS, UMR 7225, Paris, France
• ⁶COGIMAGE, UPMC Paris 6, INSERM, U1127, CNRS, UMR 7225, Paris, France

Motor imagery has been considered a substitute for overt motor execution to study post-stroke motor recovery. However, motor imagery abilities at the acute stage (<3 weeks) are poorly known. The aim of this study was to compare explicit and implicit motor imagery abilities in stroke patients and healthy subjects, correlate them with motor function, and investigate the role of right or left hemisphere lesions on performance. Twenty-four stroke patients at the acute stage and 24 age- and gender-matched healthy volunteers performed implicit (Hand Laterality Judgment Task) and explicit (number of imagined/executed hand movements) motor imagery tasks and a clinical motor assessment. Differences between healthy subjects and patients as well as the impact of lesion side on motor imagery were studied using ANOVA. We analyzed the relationship between motor executed and imagined movements (temporal congruence) using Pearson correlations. Our study shows that for implicit imagery, stroke patients had slower reaction times [RTs, t(46) = 1.7, p = 0.02] and higher error rates for the affected hand [t(46) = 3.7, p < 0.01] yet shared similar characteristics [angle effect: F(1,46) = 30.8, p ≤ 0.0001] with respect to healthy subjects. For the unaffected hand, right-sided stroke patients had a higher error rate and similar RTs whereas left sided stroke had higher RTs but similar error rate than healthy subjects. For explicit imagery, patients exhibited bilateral deficits compared to healthy subjects in the executed and imagined condition (p &ly; 0.0001). Patients and healthy subjects exhibited a temporal congruence between executed and imagined movements (p ≤ 0.04) except for right-sided strokes who had no correlation for both hands. When using motor imagery as a tool for upper limb rehabilitation early after stroke, caution must be taken related to the side of the lesion.

Introduction

Motor imagery shares a number of similarities with overt movement execution such as behavioral (Jeannerod, 1995), physiological parameters (Kranczioch et al., 2009), and perhaps more importantly, certain functional neuroanatomical correlates (e.g., recruitment of brain motor networks; Confalonieri et al., 2012). Motor imagery has been used in upper limb rehabilitation to improve post-stroke motor function (Page et al., 2011), pain (Moseley, 2006), neglect (Welfringer et al., 2011), or daily living activities (Liu et al., 2004), mostly at the subacute and the chronic stage. Two randomized controlled trials have trained patients by mental practice at the acute stage (Liu et al., 2004; Rosa et al., 2010) but one examined specifically motor function in a small sample of patients (n = 17). Yet, a clear understanding of whether and how mental simulation performance is modified by motor stroke and when is needed, especially at the acute stage. Motor imagery is actually an umbrella term that includes two different types: implicit and explicit mental imagery (Di Rienzo et al., 2014). Implicit motor imagery concerns the ability to perform mental rotation, usually with one part of the body, by a first person perspective. It can be tested by the Hand Laterality Judgment Task (HLJT) in which a subject has to determine the laterality (handedness) of pictures of hands (De Vries et al., 2011; Yan et al., 2013). In this type of task, stroke patients are susceptible to exhibit decreases in accuracy, RTs, or both. Explicit imagery is the internal rehearsal of a movement (for example, a fist closure task) that could be imagined visually or kinesthetically (Malouin et al., 2012; Wong et al., 2013). In the context of explicit imagery, the number of executed and imagined movements in a given amount of time (temporal congruence) has also been suggested to be altered in stroke patients (Di Rienzo et al., 2014). It is, however, worth noting that studies investigating these performances have been performed at the chronic phase (>3 months) except in one study (De Vries et al., 2011). In other words, motor imagery abilities at the acute stage of stroke are not well known and may be of importance to use mental practice as a tool in upper limb rehabilitation, as soon as possible. In addition, the impact of the side of the lesion on motor imagery has been questioned in a recent review (Di Rienzo et al., 2014), and for both types of motor imagery. In order to better characterize the abilities of stroke patients in implicit and explicit motor imagery, we performed a behavioral study in acute stroke patients and healthy individuals. First, we compared the characteristics of implicit and explicit imagery in healthy subjects and stroke patients. We then investigated which type of motor imagery was impaired specifically in right- and left-sided lesions. Finally, we correlated the motor imagery performance with motor function in patients.