Audrey Kittredge 593: Neuroimaging of Language
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Short-Term Reorganization of Auditory Analysis Induced by Phonetic
Experience
Liebenthal et al. (2003). JoCN.
Short-Term Reorganization of Auditory Analysis Induced by Phonetic
Experience
Liebenthal et al. (2003). JoCN.
Audrey Kittredge593: Neuroimaging of Language
Audrey Kittredge593: Neuroimaging of Language
MRI: physicsMRI: physics
Hydrogen nuclei act as magnets (spinning, charged particle)
Hydrogen nuclei act as magnets (spinning, charged particle)
MRI: physicsMRI: physics
In strong magnetic field: spin-axes form vector parallel to field
In strong magnetic field: spin-axes form vector parallel to field
MRI: procedureMRI: procedure
Radio Frequency pulse Changes direction and strength of vector
Eventually, nuclei relax and vector returns to original position
As nuclei relax, give out pulse Pulse type depends on water/fat ratio of tissue --> MRI images!
Radio Frequency pulse Changes direction and strength of vector
Eventually, nuclei relax and vector returns to original position
As nuclei relax, give out pulse Pulse type depends on water/fat ratio of tissue --> MRI images!
Functional MRIFunctional MRI
Hemoglobin shows up better than deoxyhemoglobin on MRI
SO Brain areas with more oxygenated blood will show up better (BOLD)
Hemoglobin shows up better than deoxyhemoglobin on MRI
SO Brain areas with more oxygenated blood will show up better (BOLD)
Connection to neural activity?Connection to neural activity? Increase in net neural activity --> increase in oxygenated blood supply (slow)
Quick succession of images: BOLD signal at various times
Increase in net neural activity --> increase in oxygenated blood supply (slow)
Quick succession of images: BOLD signal at various times
ProsPros
Good spatial resolution
Less risky, faster acquisition than PET
Event-related design
Good spatial resolution
Less risky, faster acquisition than PET
Event-related design
ConsCons
Poor temporal resolution BOLD signal degraded near air/bone boundary
Movement artifacts High speed data acquisition = noisy!
Poor temporal resolution BOLD signal degraded near air/bone boundary
Movement artifacts High speed data acquisition = noisy!
Phonetic perceptionPhonetic perception
How does this occur?
Automatic phonetic analysis module (Liberman & Mattingly, 1989)
Stimulus-independent auditory analysis (Kluender & Greenberg, 1989)
How does this occur?
Automatic phonetic analysis module (Liberman & Mattingly, 1989)
Stimulus-independent auditory analysis (Kluender & Greenberg, 1989)
Past ResearchPast Research
PET, fMRI studies Speech vs nonspeech: superior temporal cortex
PET, fMRI studies Speech vs nonspeech: superior temporal cortex
Problem!Problem!
Confound: perception or stimuli?
Goal: study perception mode independent of stimulus properties
How do we do this?…
Confound: perception or stimuli?
Goal: study perception mode independent of stimulus properties
How do we do this?…
…Sinewave speech!…Sinewave speech!
Sinewave example Sinewave example
Original sentenceOriginal sentence
“The steady drip is worse than a drenching rain”
“The steady drip is worse than a drenching rain”
Sinewave speech: propertiesSinewave speech: properties Sinusoid fit to center frequency and amplitude (over time) of F1-F3 or F4
Result: rapidly changing pure tones Lack fine-grained acoustic properties of speech
Sinusoid fit to center frequency and amplitude (over time) of F1-F3 or F4
Result: rapidly changing pure tones Lack fine-grained acoustic properties of speech
Past studies on sinewave speechPast studies on sinewave speech Remez et al. (1981):
“Describe”: most say non-speech “Transcribe”: most write all/some of sentence correctly
Remez et al. (1981): “Describe”: most say non-speech “Transcribe”: most write all/some of sentence correctly
Tone-matching Task(Remez et al., 2001)Tone-matching Task(Remez et al., 2001) Stimuli
Sinewave word e.g. juice Isolated T2 from T123/4 complex
Task: is tone constituent of complex?
Listeners can do this… When uninformed (not speech) While matching tone complex to printed word
Difficult task!
Stimuli Sinewave word e.g. juice Isolated T2 from T123/4 complex
Task: is tone constituent of complex?
Listeners can do this… When uninformed (not speech) While matching tone complex to printed word
Difficult task!
Creation of stimuliCreation of stimuli
Phonetic stimulus (sinewave word) 3 lowest formants = 1 sinewave each
Tone probe “True”: from word “False”: from other sinewave word
Nonphonetic stimulus T1 and T3 temporally reversed
Phonetic stimulus (sinewave word) 3 lowest formants = 1 sinewave each
Tone probe “True”: from word “False”: from other sinewave word
Nonphonetic stimulus T1 and T3 temporally reversed
Spectrogram of StimuliSpectrogram of Stimuli
Pilot studies Pilot studies
Phonetic transcribed 52.1% accuracy, multiple choice 89.5% accuracy
Rated as “Clearly identifiable word”: 61% phonetic 22% nonphonetic
“Nonspeech”: 58% nonphonetic 20% phonetic
Phonetic transcribed 52.1% accuracy, multiple choice 89.5% accuracy
Rated as “Clearly identifiable word”: 61% phonetic 22% nonphonetic
“Nonspeech”: 58% nonphonetic 20% phonetic
Stimuli: summaryStimuli: summary
288 stimuli total
108 pairs of phonetic, nonphonetic stimuli 1/3 repeated
1/2 trials = false
288 stimuli total
108 pairs of phonetic, nonphonetic stimuli 1/3 repeated
1/2 trials = false
Experimental DesignExperimental Design
Naïve 1 Naïve 2PracticePhonetic Practice
Informed1
Informed2
ProcedureProcedure
Practice Stimuli: arbitrarily composed sinusoids
Sinewaves: same/diff pitch contour?
Tone-matching task (T2-T1234) Naïve condition
“single tone”, “tone complex” 2 blocks
Practice Stimuli: arbitrarily composed sinusoids
Sinewaves: same/diff pitch contour?
Tone-matching task (T2-T1234) Naïve condition
“single tone”, “tone complex” 2 blocks
ProcedureProcedure
Phonetic practice Sinewave stimuli: 8 sentences, 18 words
Chose from 4 transcriptions Feedback given for every 5th sentence
Accuracy data collected Informed condition
“words” 2 blocks
Phonetic practice Sinewave stimuli: 8 sentences, 18 words
Chose from 4 transcriptions Feedback given for every 5th sentence
Accuracy data collected Informed condition
“words” 2 blocks
Results: RTResults: RT
Phonetic: Test Block p < .o4 (N1-N2 p < .02, N2-I1 p < .03, I1-I2 p < .05)
Nonphonetic Test Block p < .001 (N1-N2 p < .01)
In naïve condition, effect of stimulus type p < .04
Phonetic: Test Block p < .o4 (N1-N2 p < .02, N2-I1 p < .03, I1-I2 p < .05)
Nonphonetic Test Block p < .001 (N1-N2 p < .01)
In naïve condition, effect of stimulus type p < .04
Results: AccuracyResults: Accuracy
Phonetic: No significant effect of Test Block p < .11
Nonphonetic No significant effect of Test Block p < .53
In naïve condition, no effect of stimulus type p < .07
Phonetic: No significant effect of Test Block p < .11
Nonphonetic No significant effect of Test Block p < .53
In naïve condition, no effect of stimulus type p < .07
Results: Phonetic Form PracticeResults: Phonetic Form Practice Sentence task: 84 +/- 21% accuracy
Words: 60 +/- 16% accuracy
Chance = 25% in both tasks
Sentence task: 84 +/- 21% accuracy
Words: 60 +/- 16% accuracy
Chance = 25% in both tasks
Results: Subjective ReportsResults: Subjective Reports 29/31 unaware of phonetic quality during naïve blocks
13/31 recognized words during informed blocks
29/31 unaware of phonetic quality during naïve blocks
13/31 recognized words during informed blocks
Conclusions: BehaviorConclusions: Behavior
Phonetic awareness interferes with task
Naïve: subjects perceived only auditory form
Informed: subjects perceived both, focused on auditory
NO explanation for stimulus RT difference in Naïve
Phonetic awareness interferes with task
Naïve: subjects perceived only auditory form
Informed: subjects perceived both, focused on auditory
NO explanation for stimulus RT difference in Naïve
Within each block…Within each block…
2 phonetic trials
2 nonphonetic trials
Baseline (silence)
Clustered image acquisition
9s 9s 9s 9s 9s 9s 9s 9s
Image acquisitionImage acquisition
18 images per trial type per block
36 images per condition/trial type E.g. Naïve, phonetic
18 images per trial type per block
36 images per condition/trial type E.g. Naïve, phonetic
fMRI ImagesfMRI Images
16 slices: Axially oriented (horizontal) Contiguous 3x3x4mm voxels
Slice coverage: Most of temporal lobes Part of frontal and parietal lobes Occipital lobe
Anatomical (MRI) images (1x1x1mm)
16 slices: Axially oriented (horizontal) Contiguous 3x3x4mm voxels
Slice coverage: Most of temporal lobes Part of frontal and parietal lobes Occipital lobe
Anatomical (MRI) images (1x1x1mm)
fMRI analysis: individualsfMRI analysis: individuals AFNI software package Trial - Baseline-->BOLD difference maps
Difference maps: averaged (BOLD vs baseline) Voxel-wise ANOVA (sorted by trial type and condition)
AFNI software package Trial - Baseline-->BOLD difference maps
Difference maps: averaged (BOLD vs baseline) Voxel-wise ANOVA (sorted by trial type and condition)
fMRI analysis: averagingfMRI analysis: averaging Individual statistical maps transformed into standard space Talairach brain Complicated statistics, smoothing…
t values at each voxel averaged across subjects
Individual statistical maps transformed into standard space Talairach brain Complicated statistics, smoothing…
t values at each voxel averaged across subjects
fMRI analysis: significance testingfMRI analysis: significance testing Randomization testing:
t values >/= .37 significant
uncorrected voxel-wise p < .001
Activation foci < 300 microL removed
Randomization testing: t values >/= .37 significant
uncorrected voxel-wise p < .001
Activation foci < 300 microL removed
fMRI Result Summary fMRI Result Summary
fMRI ImagesfMRI Images
Phonetic: Informed-NaivePhonetic: Informed-Naive Left Heschl’s gyrus (HG/BA42)
Left posterior superior temporal gyrus (STG/BA 42/22)
Right HG/BA42
Left Heschl’s gyrus (HG/BA42)
Left posterior superior temporal gyrus (STG/BA 42/22)
Right HG/BA42
Phonetic ExperiencePhonetic Experience
Decreased activation = decreased task execution Underlies reduced performance Interference masks information like noise
STG Primate HG/post STG analogues involved in complex sound analysis, auditory STM
Left-lateralized Specialization for speech
Decreased activation = decreased task execution Underlies reduced performance Interference masks information like noise
STG Primate HG/post STG analogues involved in complex sound analysis, auditory STM
Left-lateralized Specialization for speech
Phonetic Experience cont’dPhonetic Experience cont’d No shift to other areas
No conscious phonetic perception
Phonetic experience induces “short-term functional reorganization of auditory analysis” and is contingent on “dynamic structure”
No shift to other areas No conscious phonetic perception
Phonetic experience induces “short-term functional reorganization of auditory analysis” and is contingent on “dynamic structure”
Phonetic: Informed-NaivePhonetic: Informed-Naive Dorsomedial thalamic nucleus
Superior frontal gyrus (BA8)
Left middle frontal gyrus (MFG/BA10)
Dorsomedial thalamic nucleus
Superior frontal gyrus (BA8)
Left middle frontal gyrus (MFG/BA10)
Unexplained ResultsUnexplained Results
Dorsomedial thalamic nucleus, medial prefrontal cortex: Areas with reciprocal connections to each other and ST area
Connected neural system… Engaged in task Sensitive to interference
Dorsomedial thalamic nucleus, medial prefrontal cortex: Areas with reciprocal connections to each other and ST area
Connected neural system… Engaged in task Sensitive to interference
Nonphonetic: Informed-NaiveNonphonetic: Informed-Naive Left posterior STG (BA 42/22)
Left posterior STG (BA 42/22)
Phonetic: Blocks2-Blocks1Phonetic: Blocks2-Blocks1 Left middle frontal gyrus (BA9)
Left middle frontal gyrus (BA9)
Nonphonetic: Blocks1-Blocks2Nonphonetic: Blocks1-Blocks2 Left inferior frontal gyrus (IFG/BA44)
Left inferior frontal gyrus (IFG/BA44)
Proficiency EffectsProficiency Effects
Left IFG, MFG: Initial difficulty in verbal production task (Raichle et al., 1994)
Not cause of Informed-Naïve difference (no anatomical overlap)
Left IFG, MFG: Initial difficulty in verbal production task (Raichle et al., 1994)
Not cause of Informed-Naïve difference (no anatomical overlap)
What do YOU think?What do YOU think?
Conclusions…?Conclusions…?
“Centrality” of this function Naïve: Phonetic vs nonphonetic RT Reorganization contingent on speech?
Decreased activation: underlies reduced performance?
Proficiency/Informed: frontal overlap?
“Centrality” of this function Naïve: Phonetic vs nonphonetic RT Reorganization contingent on speech?
Decreased activation: underlies reduced performance?
Proficiency/Informed: frontal overlap?
Methodology…?Methodology…?
Response/accuracy inclusion criteria?
RT/accuracy data not parallel RT: correct, incorrect, true, false trials
Word length? Age variation (18-57)? Naïve: phonetic vs nonphonetic? (fMRI)
Response/accuracy inclusion criteria?
RT/accuracy data not parallel RT: correct, incorrect, true, false trials
Word length? Age variation (18-57)? Naïve: phonetic vs nonphonetic? (fMRI)
Some questions…Some questions…
Role of thalamus/medial frontal areas?
Task difficulty --/--> activation increase
Role of thalamus/medial frontal areas?
Task difficulty --/--> activation increase
Some more questions…Some more questions…
Given phonetic practice, is reorganization entirely stimulus-driven?
How generalizable to normal speech-nonspeech analysis?
Original question: automatic phonetic module or auditory analysis?
Given phonetic practice, is reorganization entirely stimulus-driven?
How generalizable to normal speech-nonspeech analysis?
Original question: automatic phonetic module or auditory analysis?
AcknowledgementsAcknowledgements
You--thanks for listening!
Steve Higgins explanation of fMRI procedure, analysis
Gary Oppenheim practice presenting
You--thanks for listening!
Steve Higgins explanation of fMRI procedure, analysis
Gary Oppenheim practice presenting
References References
Sinewave speech information and samples obtained from: http://macserver.haskins.yale.edu/haskins/MISC/SWS/SWS.html
fMRI physics information obtained from publicly accessible websites and “Handbook of Functional Neuroimaging of Cognition”, Cabeza & Kingstone (Ed), 2001.
Sinewave speech information and samples obtained from: http://macserver.haskins.yale.edu/haskins/MISC/SWS/SWS.html
fMRI physics information obtained from publicly accessible websites and “Handbook of Functional Neuroimaging of Cognition”, Cabeza & Kingstone (Ed), 2001.
References: cont’dReferences: cont’d
Images of atoms courtesy of Duke-UNC Brain Imaging and Analysis Center website
Schematic and anatomical brain images (as well as Uncle Sam image) obtained from various publicly accessible websites and MNI brain images
Images of atoms courtesy of Duke-UNC Brain Imaging and Analysis Center website
Schematic and anatomical brain images (as well as Uncle Sam image) obtained from various publicly accessible websites and MNI brain images