Neuroplasticity following auditory working memory training post-stroke: A case study

1102 

Abstract Submission 

Ada Leung¹, Winnie Chow¹

¹University of Alberta, Edmonton, Alberta

Ada Leung  
University of Alberta
Edmonton, Alberta

Winnie Chow  
University of Alberta
Edmonton, Alberta

Recovering from a stroke is a challenging process. Working memory is one of the cognitive functions that is impacted in a stroke involving the dorsolateral prefrontal cortex. Prior studies have found that improvement in working memory abilities post-stroke is predictive of functional gains (Vallat et al., 2005). Thus, studying how working memory training induces neuroplasticity may shed light on strategies for improving everyday functions. This pilot study aimed to examine the neuroplastic effects of working memory training in a patient with an ischemic stroke resulting in damage of the frontal regions. Our goal was to examine whether auditory working memory training led to changes in auditory and visual working memory abilities, as well as self-perceived cognitive and daily living abilities.

A woman, aged 56, sustained a right cerebral infarction involving the right middle cerebral arteries six months before the experiment. In the experiment, the patient completed auditory working training that consisted of 1-back, 2-back, and 3-back tasks using spoken digits and letters as stimuli. The training lasted six weeks, five days a week, and 40 minutes a day, with increasing task difficulties across weeks. Before and after the training, the patient underwent functional magnetic resonance imaging (fMRI) on auditory 1-back and 2-back tasks and visual 1-back and 2-back tasks. Also, the patient rated her performance and satisfaction in functional activity engagement using the Canadian Occupational Performance Measures (COPM) and the Cognitive Failure Questionnaire (CFQ). These subjective ratings reflected how well the patient felt herself performing highly prioritized daily activities.
The fMRI scanning was conducted at the Peter S. Allen MR Research Center at the University of Alberta. A 3T MRI system (Siemens) with a standard birdcage head coil was used. Structural T1 weighted anatomical volumes were obtained (axial orientation, TR=2080 ms, TE=4.38 ms, FOV=256 mm, slice thickness=1 mm). The T2* weighted echo planar image sequence acquisition parameters were: TR=2000 ms, TE=30 ms, flip angle=80°, FOV=256 mm, and effective acquisition matrix=64×64 mm. Each functional sequence consisted of 36 4-mm thick axial slices, positioned to image the whole brain. The functional run began with a 30-second rest block followed by 8 blocks alternating between task and rest. A whole brain analysis was conducted using SPM12. The design matrix was modelled with blocks of 2-back, 1-back and rest for the auditory and visual tasks in the pre- and post-training scans. Contrasts were extracted with multiple comparisons controlled at p < 0.05 corrected.

The patient completed the training. In the post-training scans (compared to pre-training) there was increased neural activation in the left superior frontal gyus, the bilateral inferior parietal lobe, and multiple cerebellar regions in the 2-back > 1-back contrast for both the auditory and visual 2-back tasks. There was also increased striatal activation in the 2-back > rest contrast for the auditory 2-back task. Hit rate and reaction time increased by about 12% and 21% respectively for all the n-back tasks (averaged scores). The ratings on the COPM and the CFQ also improved.

Neuroimaging findings suggest positive learning effects, with increased frontoparietal activations and striatal activations, together with improved behavioral performance. The former is the core network for working memory (Klingberg, 2010) while the striatum is related to learning (Salminen et al., 2016; Dahlin et al., 2008). Although transfer effects of working memory training have been inconclusive (Melby-Lervåg et al., 2016), this study showed transfer effects across tasks of similar task structures. Also, the patient found daily activities slightly easier after the training. The results suggest that working memory training may be beneficial for stroke recovery. A larger sample is needed to verify the training effects.

Neurodegenerative/ Late Life (eg. Parkinson’s, Alzheimer’s) ²

Neural Plasticity and Recovery of Function ¹

Cerebrovascular Disease

FUNCTIONAL MRI

Neurological

Plasticity

Treatment