Word Reading Skill and Brain Anatomy in Adult Resilient

Readers

Suzanne Welcome1, Christiana M. Leonard2, Laura Halderman1,

Stephen Towler2, & Christine Chiarello1

University of California, Riverside1, University of Florida, Gainesville2

200 university students • 7 Divided Visual Field tasks - words presented to left and

right hemispheres• Structural MRI• Woodcock Reading Mastery Tests - Revised

– Word Identification– Word Attack – Passage Comprehension

• Wechsler Abbreviated Scale of Intelligence• Handedness preference and performance

Biological Substrates for Language Project

Resilient Readers

(n=16)

Proficient Readers (n=16)

Word Attack* 18

(10-25)

61

(46-76)

Passage Comprehension 64

(45-91)

74

(53-94)

Word Identification* 39

(18-60)

56

(30-74)

Verbal IQ 68

(37-96)

70

(37-99)

Performance IQ 66

(32-86)

68

(27-86)

Sex 9 male 9 male

Handedness 11 Right-Handed 12 Right-Handed

* Groups differ significantly (p < 0.01) on this measure

Compensation for Poor Phonological Decoding

Stanovich (1980) proposed that deficiencies in lower-level processes like phonological decoding can be compensated for by greater reliance on semantic factors like context

• Predicts that resilient readers will show normal performance on semantic tasks while showing deficits in other tasks

Study Questions• Do resilient readers show behavioral profile

consistent with semantic compensation mechanism?

• Do resilient readers differ in behavioral asymmetry from proficient readers?

• Do resilient readers differ in brain asymmetry or other aspects of brain anatomy from proficient readers?

• Do resilient and proficient readers differ in predictors of reading comprehension?

DVF ExperimentsPseudoword Naming Pronounce pseudowords created by

changing single letter of word

Word Naming Say presented word

Masked Word Recognition 2-alternative forced choice of word immediately preceded and followed by mask (@/@/@)

Lexical Decision Word/Pseudoword response made by key press

Category Member Generation

Say an example of presented category

(FRUIT – apple)

Verb Generation Say an action associated with presented noun (SCISSORS – cut)

Semantic Decision Natural/Manmade response made by key press

Brain Measures

• Gray and matter volume of cerebral hemispheres• Cerebellar volume• Total area and area of sections of corpus callosum• Length and asymmetry measures of language-

relevant regions– Planum temporale– Planum parietale– Heschl’s gyrus– Pars triangularis– Pars opercularis

DVF Task Results

• Standard RVF/LH advantage found in both accuracy and reaction time for all 7 tasks– Reading groups did not differ in asymmetry index for

any of the seven experimental tasks in either accuracy or RT

• Groups did not differ in RT on any experimental task

• Resilient readers less accurate only on tasks that do not require semantic access

*

*

*

Pseudoword Naming

Word Naming

Lexical Decision

MaskedWord Recognition

VerbGeneration

CategoryGeneration

Semantic Decision

• Resilient readers do not differ from proficient readers in any of length, area, volume or asymmetry measures

• However, relationship between measures and reading ability differs between groups

Anatomical Results

Semi-partial r2 Beta t-value Signif.

SES .0214 -.169 -0.90 NS

Handedness .0136 .176 0.72 NS

Verbal IQ .1952 .488 2.73 .023

Planum Temporale Asym.

.0308 .226 1.09 NS

Left pars opercularis length

.0234 -.185 -0.95 NS

White Matter Volume .1860 .490 2.67 .026

Predicting Passage Comprehension Scores

Proficient Readers

Resilient Readers

White matter volume and verbal IQ account for 66% of variance

White matter volume and verbal IQ account for less than 1% of variance

Semi-partial r2 Beta t-value Signif.

SES .0014 -.042 -0.13 NS

Handedness .0065 .325 0.88 NS

Verbal IQ .0212 .301 0.50 NS

Planum Temporale Asym.

.0023 -.111 -0.16 NS

Left pars opercularis length

.1072 -.414 -1.12 NS

White Matter Volume .0030 .077 0.19 NS

R2 = .482

R2 = .002R2 = .466

R2 = .089

Summary and Conclusions

• Do resilient readers show behavioral profile consistent with semantic compensation mechanism?– Resilient readers are less accurate only on tasks that do not require

semantic access

• Do resilient readers differ in behavioral asymmetry from proficient readers? – Resilient readers do not show altered pattern of behavioral asymmetry

• Do resilient readers differ in brain asymmetry or other aspects of brain anatomy from proficient readers?– Resilient readers do not differ on any measure of brain anatomy

• Do resilient and proficient readers differ in predictors of reading comprehension?– Proficient readers’ comprehension predicted well by brain volume and

verbal IQ; resilient readers’ comprehension not well predicted by any measure

Thanks!