visual-auditory interactions assessed with abr
DESCRIPTION
Visual-auditory interactions assessed with ABR Dr. W. David Hairston, Visual & Auditory Processes Branch Human Research and Engineering Directorate Army Research Laboratory. Overview. Background - Who am I, ARL, etc - Background story The Plan - Paradigm - Analysis. - PowerPoint PPT PresentationTRANSCRIPT
Visual-auditory interactions assessed with ABR
Dr. W. David Hairston, Visual & Auditory Processes Branch
Human Research and Engineering Directorate
Army Research Laboratory
Overview
• Background
- Who am I, ARL, etc
- Background story
• The Plan
- Paradigm
- Analysis
Who is this guy?
My background….Exp Psych…. BS App State, MA Wake Forest U
Multisensory target localizationNeuroscience…. PhD (Neurobiology) Wake Forest U
(Mark Wallace) Multisensory perceptual interactions in time and space
Brain imaging…. Post doc (Radiology) Wake Forest U(Laurienti, Burdette, Maldjian)Cross-modal interactions with attention
(music conductors) and timing (dyslexia)Now…. Research fellowship w/ Army Research Lab
(Letowski, McDowell) Cross-modal workload influence on auditory processing
No experience in audiology
ARL?
US Army
Research, Development, and engineering Command
Human Research and Development
Visual and Auditory Processes Branch
Auditory Research Team
Officially – Oak Ridge Associated Universities
Army Research Lab
Interests…
My Interests:Visual-Auditory integrationMultisensory interactions – how processing in one sense affects others…
not just in good ways…(e.g. dark ugly downside to cross-modal interactions)
Role of experience – can focused training not only hone sense(s), but also affect how they interact with each other?(e.g. can detrimental interactions be avoided?)
ARL’s interests…Application – how can we use multisensory research to enhance US
Soldier?(e.g., can specific types of training enhance sensory awareness? Or, can detrimental affects be overcome?)
Programatic – How can neuroscientific methods be easily integrated into other ARL studies of human perception (e.g., sound localization, human factors, etc)
Research Background
Multisensory interactions….Many studied effects from multisensory stimulationClassically, examined as V+A vs V or A…. “Is 2 better than 1?”
Lots of good stuff - Behaviorally: faster response times, higher accuracy, better memory
- Neurophysiologically: bigger responses, decreased latency, lower S/N, etc.
(even in this lab – enhanced FFR, cortical response slope)
But what about cases where you don’t WANT integration?Not everything we do is multisensory…
Research Background
Cross-modal inhibition….
Sometimes you really need to focus on just one sense…Reading a book in a noisy roomTalking on phone (not while driving!)
“Cross-modal attention” (hate that word)shift mental resources from one sense to another
2.78 7.0
-2.78 -7.0
Deactivation of auditory cortex
during visual task
Research Background
Own recent work… role of task difficulty
440 Hz 660 Hz
440 Hz 660 Hz
Easier
Difficult
60 ms
20 ms
Temporal Discrimination
Subjects’ thresholds for each task acquired prior to fMRI scanning
Non-musicians: Moderate
Deactivation of visual cortex
+/-3.95 +/-8.0
Vis Response
Non-musicians: Difficult
Robust deactivation of visual cortex
+/-3.95 +/-8.0
Vis Response
Non-musicians vs. Conductors
Difference seen when task is difficult
0
40
80
120
160
200
Easier Difficult
N S
ign
if V
oxe
ls
Non-musicians
Conductors
n.s.
**
0
20
40
60
80
High M oderate
Acc
ura
cy(%
)
Highly trained concert
conductors (>7 yrs
experience) do NOT show
this trend
Suggests the inhibition can be mediated by experience/training
Research Background
So…. What about the brainstem?
Begs the question… does cross-modal inhibition affect most basic, incoming auditory processing?
We know that the ABR is affected by multisensory processing – (enhancement) and this is tied to cortical enhancement(Thanks Auditory Neuroscience Lab!)
… but what about suppression?
Increased FFR amplitude w/ Auditory attention vs visual(Galbraith)-but unclear if this is aud enhancement or visual suppression
(no no-stim baseline)
Question at hand…
• Does cross-modal task difficulty directly affect ABR-level processing?
• What are the implications at the level of both the brainstem and cortical response?
The Plan
Use ABR-based recording techniques while subjects perform visual, auditory, and baseline (no) tasks at different levels of difficulty
The Plan
ABR Stim
Oddball
Stim: 220 Hz tone, 100 ms duration 400 ms ISI
Infrequent oddball (5%?) 235 Hz
ABR
Task
Jittered, 4 sec ave ISI between stim
The Plan
Visual
Auditory
X 2 = Easy + Hard
No task
Tasks?
Tasks…?Temporal discrimination
N-Back
Motion detection
Must be similar in both modalities, and manipulated to “easy” and “hard” levels
440 Hz 660 Hz
440 Hz 660 Hz
Easier
Difficult
60 ms
20 ms
Analysis
• Interested in FFR of ABR – shown to be most affected by VA-interactions, cognitive influence etc
• Also cortical (MMN) responses associated with oddballs, and correlation with FFR
• Ideally limit # of trials to minimum – save time, more practical
Analysis
Typical FFR…
Trial 1 Trial X Mean Signal
+ =
FFT of Mean
Advtantage:
Proven method, have full data, derive timing (onset), signal amplitude and FFT
amplitude
Disadvantage: requires many trials for waveform to average out, requires pefect
time-lock response; time consuming
Analysis
Fourier-Average FFR….
Trial 1 Trial X
+ =
Mean FFT
Advantage:
Many fewer trials needed; no need for perfect phase locking – saves time!
Disadvantage: Loss of temporal structure; computationally intensive
Option 1 – FFT every trial,
average over 1000 trials
Option 2 – averge clusters
(10?), average over clusters
(100) MMN/cortical –
standard
averaging
technique
Expectations…
1. (I learn how to do ABR)2. Larger FFR response in A- task than V3. Decreased V (suppression) relative to baseline4. Effect (3) most pronounce in difficult task
(e.g., minimal/no diff in easy task)5. Latency of MMN correlated with FFR modulation6. (eventually) – Effects (4,5) diminished with training, or
specific kind of expertise
Alternative: cross-modal effect may be in baseline noise shift (SNR) rather than amplitude change
Equally enticing!
Done!
Open to ideas!
Unresolved:
Ideal tasks
Ideal ABR stim (pure vs complex tone)
How many trials
Individual vs cluster FFT
Min effective sample rate (data reduction)