fmri and reading einar mencl, haskins laboratories, new haven, ct usa
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fMRI and Reading
Einar Mencl, Haskins Laboratories, New Haven, CT USA
Koby finishes 49 in 12 minutes;Einar finishes 61 in…?
Collaborators
• Haskins Laboratories: Ken Pugh, Rebecca Sandak, Stephen Frost, Dina Moore, Stephanie Mason, Leonard Katz, Jay Rueckl, Donald Shankweiler, Annette Jenner, Jun Ren Lee, Carol Fowler, Ram Frost
• Yale Center for the Study of Learning and Attention: Bennett Shaywitz, Sally Shaywitz, Karen Marchione, John, Holahan, Jack Fletcher
• Yale University/Diagnostic Radiology: John Gore, Todd Constable, Robert Fulbright, Pawel Skudlarski, Cheryl Lacadie
Haskins - 270 Crown Street, New Haven CT
Haskins - 300 George Street, New Haven CT
Haskins - 300 George Street, New Haven CT
Haskins Folks (1)
Haskins Folks (2)
Behavioral Background
1) motor theory of speech perception; phonology 2) Evidence from fast priming: (Turvey, Lueketela, & Frost) a) toad - frog b) tode - frog c) towed - frog
Behavioral Background
1) motor theory of speech perception; phonology 2) Evidence from fast priming: (Turvey, Lueketela, & Frost) a) toad - frog b) tode - frog c) towed - frog
3) What is the best prime for a word? 1) fort - fort (identity)
Behavioral Background
1) motor theory of speech perception; phonology 2) Evidence from fast priming: a) toad - frog b) tode - frog c) towed - frog
3) What is the best prime for a word? 1) fort - fort 2) bowl - bowl?
Behavioral Background
1) motor theory of speech perception; phonology 2) Evidence from fast priming: a) toad - frog b) tode - frog c) towed - frog
3) What is the best prime for a word? 1) fort - fort 2) bowl - bowl? >>> boll - bowl (!) alternate pronounciations: howl, scowl
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
Case MixingExp. (design)
Subjects get 10 scan runs, each 5:40 long
Each run, they see 5 blocks of baseline trials:
//*\ or /\\/
and 4 blocks of lexical decision trials:1 high frequency unmixed case2 low frequency unmixed case3 high frequency mixed case4 low frequency unmixed case
charm or cHaRm
Case Mixing Exp. (design)
1 baseline /\*/2 HF unmixed case3 LF unmixed case4 HF mIxEd CaSe5 LF mIxEd CaSe
Case MixingExp. (1)
single-subjectwords - lines
1 baseline /\*/2 HF unmixed case3 LF unmixed case4 HF mIxEd CaSe5 LF mIxEd CaSe
Case MixingExp. (2)
single subjectmixed - unmixed
1 baseline /\*/2 HF unmixed case3 LF unmixed case4 HF mIxEd CaSe5 LF mIxEd CaSe
Case MixingExp. (12)
across subjecthigh frequency wordsmixed - unmixed
1 baseline /\*/2 HF unmixed case3 LF unmixed case4 HF mIxEd CaSe5 LF mIxEd CaSe
Case MixingExp. (13)
across subjectlow frequency wordsmixed - unmixed
1 baseline /\*/2 HF unmixed case3 LF unmixed case4 HF mIxEd CaSe5 LF mIxEd CaSe
Case Mixing (14): Time effects in IFG
Case Mixing (15): Time effects in OT
Event-Related Designs, Two Analyses
1) Using a priori predicted response functions a) long intertrial interval designs b) Reference waveform regression2) Estimating the actual response a) simple averaging b) delta function regression (FIR, finite impulse response)3) Some examples
Simulated Hemodynamic Response (1)
mean = 5000sd = 100effect size 0-1%, 0-50 pointsGamma function tau=1.08; n=3; delay=3
Simulated Hemodynamic Response (2)
Noise SD = 0
Noise SD = 10
Noise SD = 100
Event-Related Designs, Two Analyses
1) Using a priori predicted response functions a) long intertrial interval designs b) Reference waveform regression2) Estimating the actual response a) simple averaging b) Delta Function Regression3) Some examples
Long Intertrial Intervals, Single Conditioncf. Ni et al., (2000)
Event Regressor
Simulated Data
Long Intertrial Intervals, Multiple Conditions
Cond 1Cond 2
Cond 1Cond 2
Event Regressors
Simulated Data
Multiple Regression (3):Reference Waveform Regression
Friston et al. 1994 int C1 C2
Cond 1Cond 2
Variability of the HRFAguirre et al., 1998
Event-Related Designs, Two Analyses
1) Using a priori predicted response functions a) long intertrial interval designs b) reference waveform regression2) Estimating the actual response a) simple averaging b) delta function regression3) Some examples
Estimating the Response (1):Simple Averaging, No Overlap
Cond 1Cond 2
Estimating the Response (2):Simple Averaging, With Overlap
Cond 1Cond 2
Estimating the Response (3):Simple Subtraction with Overlap
Dale & Buckner, 1997
Delta Function Regression (1)
Meizin et al., 2000
Delta Function Regression (2)Cond 1Cond 2
EventRegressorsFor Cond 1
EventRegressorsFor Cond 2
-1 0
+1+2+3
.
.
.+15P
eris
timul
us
Tim
e
Delta Function Regression (3)
Cond 1 Cond 2___
Cond 1
Cond 2
Delta Function Regression (4):Evoked Responses
Estimated Response
Peristimulus Time
Imag
e In
tens
ity
Imag
e In
tens
ity
Delta Function Regression (5): Overlapping Responses
Cond 1Cond 2
Cond 1 Cond 2___
Estimated Response & Gamma Fits
Delta Function Regression (6):Gamma Fitting
Peristimulus Time
Imag
e In
tens
ity
Imag
e In
tens
ity
Estimated Response
Peristimulus Time
Imag
e In
tens
ity
Imag
e In
tens
ity
Baseline Timepoints[-1 to 0]
Activation Timepoints[+3 to +8]
Delta Function Regression (4):“Blocklet” Analysis
Compare & Contrast...
Reference Waveform Regression 1) most designs are analyzable 2) stronger power 3) biased when reference <> actual
Delta Function Regression 1) some designs not analyzable 2) weaker power 3) unbiased measure of temporal response
Primed Lexical Decision Experiment (intro)
5 trialtypes: orthographic phonological
prime target relationship relationship
1 O+P+ bribe TRIBE similar similar2 O+P- couch TOUCH similar dissimilar3 NWO+ bliss TRISS similar similar4 NW brick THILM dissimilar dissimilar5 UNRE lunch TRUNK dissimilar dissimilar
LD/Prime Exp. (intro)
1 bribe - TRIBE2 couch - TOUCH3 bliss - TRISS4 brick - THILM5 lunch - TRUNK
LD/PrimeExp. (1)
single subjectunrelated primelunch - TRUNK
1 bribe - TRIBE2 couch - TOUCH3 bliss - TRISS4 brick - THILM5 lunch - TRUNK
LD/PrimeExp. (2)
raw time course
1 bribe - TRIBE2 couch - TOUCH3 bliss - TRISS4 brick - THILM5 lunch - TRUNK
LD/PrimeExp. (4)
across subjects
bribe - TRIBE
1 bribe - TRIBE2 couch - TOUCH3 bliss - TRISS4 brick - THILM5 lunch - TRUNK
LD/PrimeExp. (5)
across subjects
couch - TOUCH
1 bribe - TRIBE2 couch - TOUCH3 bliss - TRISS4 brick - THILM5 lunch - TRUNK
LD/PrimeExp. (6)
across subjects
couch - TOUCH vsbribe - TRIBE
1 bribe - TRIBE2 couch - TOUCH3 bliss - TRISS4 brick - THILM5 lunch - TRUNK
LD/PrimeExp. (6)
across subjects
couch - TOUCH vsbribe - TRIBE
1 bribe - TRIBE2 couch - TOUCH3 bliss - TRISS4 brick - THILM5 lunch - TRUNK
LD/PrimeExp. (1)
across subjectregion timecourses
1 bribe - TRIBE2 couch - TOUCH3 bliss - TRISS4 brick - THILM5 lunch - TRUNK
titration of stimulus duration
+
house
&&&&&
1000 msec
500/1500 msec
25/50/100 msec
1000 msec
titration of stimulus duration (2)
Interactivity: Phonology and Semantics
(Strain et al. 1999)
• RT faster for hi-imageability words
• Imageability modulates Cons x Freq
• Triangle model exhibits same pattern
• Does the brain…?
Design
Go/no-go naming in a block fMRI session
Stimuli:• Words (Consistency x Imageability x Frequency)• Pseudowords
IFG = Consistency
MTG =Imageability
Region of interest analysis
(Main effect)
(Main effect)
Frost, et al., 2005, Neuroreport
Cross-Linguistic Effects - Word Frequency
…and implications for developmental dyslexia…
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