Perceptual Sequence Learning Is More Severely Impaired than Motor Sequence Learning in Patients with Chronic Cerebellar Stroke

Abstract

Patients with cerebellar stroke are impaired in procedural learning. Several different learning mechanisms contribute to procedural learning in healthy individuals. The aim was to compare the relative share of different learning mechanisms in patients and healthy controls. Ten patients with cerebellar stroke and 12 healthy controls practiced a visuomotor serial reaction time task. Learning blocks with high stimulus-response compatibility were exercised repeatedly; in between these, participants performed test blocks with the same or a different (mirror-inverted or unrelated) stimulus sequence and/or the same or a different (mirror-inverted) stimulus-response allocation. This design allowed to measure the impact of motor learning and perceptual learning independently and to separate both mechanisms from the learning of stimulus-response pairs. Analysis of the learning blocks showed that, as expected, both patients and controls improved their performance over time, although patients remained significantly slower. Analysis of the test blocks revealed that controls showed significant motor learning as well as significant visual perceptual learning, whereas cerebellar patients showed only significant motor learning. Healthy participants were able to use perceptual information for procedural learning even when the rule linking stimuli and responses had been changed, whereas patients with cerebellar lesions could not recruit this perception-based mechanism. Therefore, the cerebellum appears involved in the accurate processing of perceptual information independent from prelearned stimulus-response mappings.

Learning temporal statistics for sensory predictions in mild cognitive impairment

“…Finally, our results are consistent with recent work implicating cerebellum in sequence learning (e.g. serial reaction task) (Dirnberger et al, 2013;Tzvi et al, 2014) and predictive processing (Kotz et al, 2014;Leggio and Molinari, 2014).…”

Is Implicit Motor Learning Preserved after Stroke? A Systematic Review with Meta-Analysis

“…Across studies, considerable heterogeneity was noted in terms of patient characteristics, such as patients’ mean age (range: 46–74 years), time since stroke (range: 1.9–88 months) and lesion location. With regard to the latter, three studies investigated patients with isolated cerebellar lesions [54,74,75], six studies incorporated patient groups with isolated supratentatorial subcortical lesions [50,51,55,73,76,79], four studies studied patient groups with mixed supratentatorial subcortical- and/or cortical lesions [49,52,70,71], while 2 studies incorporated patient groups with mixed sub- and supratentatorial lesions [32,52]. Finally, in five studies lesion location was only described as being supratentatorial and not further specified [68,69,72,77,78].…”

“…Overall, most studies exhibited moderate to high risk of bias (see the supplementary material for justification of NOS-scores). This was for a large part due to lack of detail on participant screening and selection (cf [70]), lack of assessment of/correction for confounding factors [47,49–51,55,68,69,71–73,75–79], and lack of reporting on the amount of participants’ explicit movement-related knowledge [49,51,54,68–70,72,78]. In fact, in some studies participants gained so much explicit knowledge that learning may have been explicit, rather than implicit [55,71,73,77].…”

“…Of the three studies that were pooled two included patients with isolated cerebellar lesions [74,75], while one studied patients with isolated supratentatorial subcortical lesions [76]. We pooled results using a fixed effects model with the mean difference in reaction time between repeated and random blocks as outcome measure (Fig 5).…”

“…Further, a significant limitation of those studies that contrasted implicit motor learning of patients with healthy controls is the lack of information regarding group comparability. Confounders such as motor or cognitive functioning often were neither reported for the patient and control groups [47,49,50,55,68,69,71,73,75–79], nor matched across groups or corrected for in the analysis of implicit motor learning [47,49–51,68,69,71–73,77,79]. This makes it difficult to assess the representativeness of patients of the general stroke population and the comparability of stroke and control groups, resulting in a high risk of selection bias.…”