The session will start with a WIP by Hanna Smyth.
Overview of WIN engagement activities and the Engagement Ambassador scheme (applications open for the month of November).
GABA and Glutamate in hMT+ Link to Individual Differences in Residual Visual Function After Occipital Stroke
Presented by Hanna Willis
BACKGROUND: Damage to the primary visual cortex following an occipital stroke causes loss of conscious vision in the
contralateral hemifield. Yet, some patients retain the ability to detect moving visual stimuli within their blind field. The present
study asked whether such individual differences in blind field perception following loss of primary visual cortex could be
explained by the concentration of neurotransmitters γ-aminobutyric acid (GABA) and glutamate or activity of the visual
motion processing, human middle temporal complex (hMT+).
METHODS: We used magnetic resonance imaging in 19 patients with chronic occipital stroke to measure the concentration
of neurotransmitters GABA and glutamate (proton magnetic resonance spectroscopy) and functional activity in hMT+
(functional magnetic resonance imaging). We also tested each participant on a 2-interval forced choice detection task using
high-contrast, moving Gabor patches. We then measured and assessed the strength of relationships between participants’
residual vision in their blind field and in vivo neurotransmitter concentrations, as well as visually evoked functional magnetic
resonance imaging activity in their hMT+. Levels of GABA and glutamate were also measured in a sensorimotor region,
which served as a control.
RESULTS: Magnetic resonance spectroscopy-derived GABA and glutamate concentrations in hMT+ (but not sensorimotor
cortex) strongly predicted blind-field visual detection abilities. Performance was inversely related to levels of both inhibitory
and excitatory neurotransmitters in hMT+ but, surprisingly, did not correlate with visually evoked blood oxygenation level–
dependent signal change in this motion-sensitive region.
CONCLUSIONS: Levels of GABA and glutamate in hMT+ appear to provide superior information about motion detection
capabilities inside perimetrically defined blind fields compared to blood oxygenation level–dependent signal changes—in
essence, serving as biomarkers for the quality of residual visual processing in the blind-field. Whether they also reflect a
potential for successful rehabilitation of visual function remains to be determined.
Improving sleep after stroke: A randomised controlled trial of digital cognitive behavioural therapy for insomnia
Presented by Melanie Fleming
Abstract: Stroke is frequently accompanied by long-term sleep disruption. We therefore aimed to assess the efficacy of digital cognitive behavioural therapy for insomnia to improve sleep after stroke. A parallel group randomised controlled trial was conducted remotely in participant's homes/online. Randomisation was online with minimisation of between-group differences in age and baseline Sleep Condition Indicator-8 score. In total, 86 community-dwelling stroke survivors consented, of whom 84 completed baseline assessments (39 female, mean 5.5 years post-stroke, mean 59 years old), and were randomised to digital cognitive behavioural therapy or control (sleep hygiene information). Follow-up was at post-intervention (mean 75 days after baseline) and 8 weeks later. The primary outcome was self-reported insomnia symptoms, as per the Sleep Condition Indicator-8 (range 0-32, lower numbers indicate more severe insomnia, reliable change 7 points) at post-intervention. There were significant improvements in Sleep Condition Indicator-8 for digital cognitive behavioural therapy compared with control (intention-to-treat, digital cognitive behavioural therapy n = 48, control n = 36, 5 imputed datasets, effect of group p ≤ 0.02, ηp2 = 0.07-0.12 [medium size effect], pooled mean difference = -3.35). Additionally, secondary outcomes showed shorter self-reported sleep-onset latencies and better mood for the digital cognitive behavioural therapy group, but no significant differences for self-efficacy, quality of life or actigraphy-derived sleep parameters. Cost-effectiveness analysis found that digital cognitive behavioural therapy dominates over control (non-significant cost savings and higher quality-adjusted life years). No related serious adverse events were reported to the researchers. Overall, digital cognitive behavioural therapy for insomnia effectively improves sleep after stroke. Future research is needed to assess earlier stages post-stroke, with a longer follow-up period to determine whether it should be included as part of routine post-stroke care.