# Directly testing the magnocellular theory of dyslexia

> **NIH NIH R01** · UNIVERSITY OF DELAWARE · 2021 · $371,573

## Abstract

Abstract
The goal of this project is to directly test the magnocellular theory of dyslexia (MTD) by measuring the
function of the magnocellular (M) system in the thalamus. Dyslexia is a reading specific disorder that
affects 5% of the population. The MTD is a prominent but controversial theory that proposes that the
behavioral deficits in dyslexia are a consequence of the dysfunction of the M system in the brain, which
is specialized for the processing of transient information. Because the M system cannot be isolated
behaviorally, and because the M stream becomes intermixed with other streams in the cortex, the MTD
has never been properly tested. However, the M system remains spatially segregated in the sensory
nuclei in the thalamus. Therefore, the MTD will be tested using high-resolution functional magnetic
resonance imaging (fMRI) to measure thalamic function in each of three independent aims:
1. Is temporal processing in the lateral geniculate nucleus (LGN) and thalamic reticular nucleus
 (TRN) normal in dyslexia?
2. Does the M portion of the medial geniculate nucleus (MGN) function normally in dyslexia?
3. Does attention modulate the LGN, MGN and TRN normally in dyslexia?
In Aims 1 and 2, measuring the M systems in the MGN and LGN will determine whether M
dysfunction, if present, is a general property of the brain in dyslexia, or whether it is confined to a single
sensory system. One of the primary functions of the thalamus is to control attention, and Aim 3 will test
whether the attentional deficits that have been reported in dyslexia are specific to the M system.
Together these experiments provide a comprehensive test of MTD and will serve to resolve its validity.
which will have an important impact on the understanding and treatment of dyslexia.
 This project will use a combination of simple stimuli and experimental designs with
experimental and analytical techniques that have been proven in our lab to be able to reliably examine
the small and noisy subcortical nuclei, including: high-resolution fMRI; massively averaged high-
resolution proton-density weighted images that can resolve the anatomical boundaries of the subcortical
nuclei; population receptive field modeling of temporal responses and retinotopic and tonotopic
organization; and data-driven filtering and clustering.
 The results of this project will provide an unprecedented direct test that will ultimately settle the
legitimacy of the MTD. This will help guide the allocation of future resources in understanding and
treating dyslexia.

## Key facts

- **NIH application ID:** 10200059
- **Project number:** 5R01EY028266-04
- **Recipient organization:** UNIVERSITY OF DELAWARE
- **Principal Investigator:** KEITH ALLAN SCHNEIDER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $371,573
- **Award type:** 5
- **Project period:** 2018-09-30 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10200059

## Citation

> US National Institutes of Health, RePORTER application 10200059, Directly testing the magnocellular theory of dyslexia (5R01EY028266-04). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10200059. Licensed CC0.

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