Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Doctor of Philosophy

Program

Psychology

Supervisor

Ansari, Daniel

Abstract

This PhD thesis explores the shared neural mechanisms between arithmetic and phonological processing and examines intergenerational influences on these abilities through a series of studies utilizing neuroimaging data from children and their mothers. The overlap between mathematics and reading has been largely hypothesized, bur very rarely tested directly within participants. During Study 1, I provided direct evidence of the association of arithmetic and phonological abilities in the brain. Conjunction analyses showed significant overlap in adults along the inferior frontal gyrus, inferior temporal gyrus and the cerebellum. In children, overlap was observed in multiple regions of the frontal cortex. Notably, our results indicated that overlapping activation was different when considering small or large arithmetic problems separately and therefore, the associations between each problem type and phonological processes required further exploration. In Study 2, I examined of these areas of significant overlap also displayed similar multivariate patterns of brain activity. Moreover, I hypothesized that verbal retrieval strategies would be more frequent during small problems, and therefore the neural mechanisms supporting the solution of these problems would be more similar to phonological processing mechanisms than large problems. Against our prediction, large problems consistently displayed greater pattern similarity with the rhyming condition, suggesting that arithmetic and phonology may share other mechanisms of verbal processing in addition to the retrieval of phonological representations. Finally, in Study 3, I examined the intergenerational influences in the neural correlates of mathematics and reading. Familial concordance was observed in several brain regions of the frontal cortex during arithmetic tasks, and in the hippocampus during phonological processing. I also investigated if similarities in whole-brain functional connectivity between parents and children were strong enough to accurately predict familial relationships. I found that connectivity matrices contained information that identified participants across multiple tasks; however, parent-child dyads could not be identified using this approach. Critically, this study emphasized the need for better methods of feature selection that can be informative of specific parent-child relationships.

Summary for Lay Audience

This research investigates the links between arithmetic and reading in the human brain; and how the brain mechanisms that participate in these abilities might be passed from parents to children.

Previous studies have proposed that remembering the solution of a simple addition problem that has been memorized is very similar to remembering the sound of a known word. I tested this idea in Study 1 and identified specific regions of the brain that are active when participants read words, but also when they solve arithmetic problems. For adults, these areas were located in anatomical regions known as the frontal gyrus, temporal gyrus, and cerebellum. In children, overlap was found in the frontal part of the brain.

But one limitation of the study 1 is that a single area of the brain can participate in many different processes. Just because an area is “active” during arithmetic and word reading it does not mean that a similar process is occurring. Because of that, in study 2 I analyzed the fine-grained pattern of response of the areas identified before, I found that brain responses were, in fact, similar during arithmetic cand reading on those regions. However, I expected that the neural response of these areas when participants solved simpler problems (which are easier to remember from memory) would be more similar to the response observed when participant remember the sound of a word. The results were surprising: more complex math problems actually showed a stronger connection with language-related brain activity. This suggests that math and language might share more complex brain processes than we previously thought.

The final part of the study focused on comparing the brain activity of parents and children. I found that some brain areas showed similar activity between mothers and their children during both reading and math. I also tried to see if the way different brain areas communicate with each other could predict who was related, but this method didn’t work well foridentifying parent-child pairs. This suggests that we need better ways to study how brain patterns are passed from one generation to the next.

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