Monday, May 14, 2018
An Integrated Brain-Behaviour Model for Working Memory
Moser, D.A., Doucet, G.E., Ing, A., Schumann, G., Bilder, R.M., Frangou, S. (2017). An integrated brain-behaviour model for working memory. Molecular Psychiatry (00), 1-7.
This paper examines function of the brain’s working memory (WM) network and how it relates to behavioural and health factors. Working memory refers to the ability to hold task-relevant information in mind. Previous studies have shown that WM depends on activity coordinated across multiple regions of the brain, including the dorsolateral prefrontal cortex, the parietal cortex, and the dorsal anterior cingulate cortex. Function of this WM network can be characterized using functional magnetic resonance imaging (fMRI), an imaging technique that measures brain activity by detecting changes associated with blood flow. Three fMRI methods were examined in this study: (1) Regional activation, which involves looking at functional activation in specific areas of the brain during a task. (2) Functional connectivity, which examines correlations in activity between different brain regions to infer how these areas are functionally connected. And (3) Effective connectivity, which studies systematic changes in activity over time to assess causal interactions between brain regions. Using these, the aim of the study was to examine the relationship between function of the brain’s WM network and behavioural and health factors.
Participants were 828 healthy adults, between 22 and 37 years old. They underwent an fMRI scan while performing a 2-back WM task, in which they were asked to indicate whether a visual stimulus matched the stimulus from two trials before. They also completed a number of measures of sensorimotor processing, cognition, mental health, personality, physical health, and lifestyle factors.
Using a statistical technique called sparse canonical correlations to examine relationships between the neuroimaging and behavioural-health datasets, results indicated a significant association between WM function and all behavioural variables. Positive correlations were observed for cognitive and physical attributes, and negative correlations observed for suboptimal health indicators and negative lifestyle choices. Results across the fMRI measures underscored a relationship between working memory and non-affective cognition for both activation of the regions within the network and connections between the network. Correlations with physical health variables were observed for other areas of the brain, suggesting that this relationship was not specific to the WM network.
Overall, these findings suggest that function of the WM network is optimal in individuals with better cognitive abilities and physical well-being, while functional connectivity across the whole brain is reduced in individuals with suboptimal health and substance abuse. This study highlights the usefulness of measuring connectivity across the brain when studying cognitive processes, rather than examining brain areas in isolation. Applied to clinical practice, this highlights the importance of making connections. Drawing links between information and integrating multiple modalities into therapy sessions may help to engage more brain areas and strengthen connections between these brain areas.
Blogger: Alex Cross is an M.Cl.Sc. and Ph.D. Candidate in Speech-Language Pathology, supervised by Dr. Lisa Archibald and Dr. Marc Joanisse.