fMRI Setup

fMRI Setup

slice orientations

axial

sagittal coronal

SPGR Anatomics (1)

resolutionin-plane 0.9375 mm2

through-plane 1.5 mm

SPGR Anatomics (2)

SPGR Anatomics (3)

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Diffusion-Weighted Imaging (1)

Diffusion-Weighted Imaging (2)

Diffusion-Weighted Imaging (3)

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Slice Locations

Auditory versus Visual Sentence Task

Constable, Pugh et al., (NeuroImage 2004)

common print(red) speech(blue)

R - L

An Initial Neurobiological Reading Model

ANTERIORAreas:

inferior frontal gyrus (including Broca’s area)

One Hypothesized Function:Articulatory recoding

OCCIPITOTEMPORAL (VENTRAL)

Areas: occipitotemporal juncture, middle and inferior temporal gyriHypothesized Function: Linguistically structured memory- based fast word identification system (posterior aspect = “word-form” area)

TEMPOROPARIETAL(DORSAL)

Areas:supramarginal, angular, superior temporal (Wernicke’s) gyri

Hypothesized Function:Mapping of orthographic to phonological and semantic representations

(Pugh et al. 2000)

Auditory versus Visual Sentence Task

Constable, Pugh et al., (NeuroImage 2004)

common print(red) speech(blue)

R - L

temporoparietal

occipitotemporal

anterior

Vasculature

Menon & Kim, Trends in Cognitive Sciences, 3(6), 1999.

Vasculature

Menon & Kim, Trends in Cognitive Sciences, 3(6), 1999.

Simulated Hemodynamic Response (1)

mean = 5000sd = 100effect size 0-1%, 0-50 pointsGamma function tau=1.08; n=3; delay=3

Variability of the HRF (1)Meizin et al., 2000

Simulated Hemodynamic Response (2)

Noise SD = 0

Noise SD = 10

Noise SD = 100

Estimating the Response (3):Simple Subtraction with Overlap

Dale & Buckner, 1997

Linear Deconvolution

Neuronal activity is modeled as a sequence of point events.slide courtesy of Matthew Brown, University of Western Ontario

Functional Connectivity

activations in Shaywitz et al. 2002

older good readers

74 good readers 7-18 yrs70 dyslexic readers 7-18 yrs

Functional Connectivity

seed voxel correlations

older good readers

Older Non-Impaired

Older Dyslexics Younger Dyslexics

Younger Non-Impaired

Functional Connectivity

univariate correlations