Alvarez, Travis
(2019)
Exploring functional specialization within cerebro-cerebellar circuits for reading.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
According to the cerebellar deficit hypothesis [CDH; (Nicolson, Fawcett, & Dean, 2001)], cerebellar dysfunction can place children at risk for developmental dyslexia. In a recent meta-analytic review, Alvarez and Fiez (2018) proposed a neural model for how the cerebellum interfaces with the cerebral reading network (CDHn). This model posits that two regions in the cerebellum, one in lobule HVIIB and one in lobule Crus1, are interconnected with the cerebral cortex to form a dorsal fronto-parietal and a ventral fronto-temporal circuit, respectively. Moreover, the CDHn model asserts that these circuits are functionally specialized, with the dorsal circuit biased towards phonological processing and the ventral circuit biased towards semantic processing. This dissertation employs functional connectivity and neural activation measures obtained with magnetic resonance imaging to empirically test the CDHn model, with an a priori focus on the five regions proposed as constituents of its dorsal and ventral circuits. Resting-state analyses tested for patterns of functional connectivity between the predefined constituents, with a special interest in circuit specialization within an inferior frontal junction region that is part of both circuits. Univariate and multivariate methods were used to characterize the predicted phonological versus semantic task biases between the dorsal and ventral circuit, respectively. Finally, the products of these analyses were used to test whether activation in cerebellar regions VIIB and Crus1 modulate neural representation in the cerebral constituents of the dorsal and ventral circuits, respectively. Conventional connectivity analyses revealed stronger evidence supporting the ventral circuit. However, success in our more unique connectivity approach to find circuit specialization within the frontal region implicated the presence of dissociative dorsal and ventral networks. As predicted, the parietal region successfully characterized a task-bias for phonological processing; no biased effect within the frontal region; and a trend towards a semantic bias within the temporal region. All cerebral regions succeeded in the multivariate task-dissociation. Although the cerebellar regions did not exhibit predicted functional specialization, the univariate analyses did uncover interactions of tasks, and Crus1 engagement was successful in modulating the semantically related properties of the temporal region. Overall, we found encouraging but incomplete support for the recently proposed CDHn model.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
9 April 2019 |
| Date Type: |
Submission |
| Defense Date: |
4 April 2019 |
| Approval Date: |
26 September 2019 |
| Submission Date: |
17 May 2019 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
85 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Psychology |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
No |
| Uncontrolled Keywords: |
Cerebellum, reading network, cerebellar deficit hypothesis, dorsal, ventral, phonological, semantic |
| Date Deposited: |
26 Sep 2019 20:31 |
| Last Modified: |
26 Sep 2019 20:31 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/36410 |
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