Ruth Litovsky University of Wisconsin Madison, WI USA

transcript

Ruth LitovskyUniversity of

WisconsinMadison, WI USA

Brain Plasticity and Development in Children and Adults with

Cochlear Implants

Litovsky@waisman.wisc.eduhttp://www.waisman.wisc.eduWaisman DWE June 23 2013

How are CI users doing?

The CI converts acoustic input into electrical stimulation of the auditory nerve to provide: Speech/Language Music Sound localization Quality of life Etc…

How are CI users doing?World-wide ~ 250,000 recipients Speech/Language Music Sound localization Quality of life Etc…

How are CI users doing? Is the glass “half full” or “half

empty” ?The field has come a long

way….Many CI users have excellent speech production and receptive language skills.But, other CI users struggle to

attain speech and language, especially without “speech reading” (auditory only)

Language comprehension Language expression

Niparko et al. (2010)

Our recent research shows that:1) Language perception: most children are within 1 SD of mean2) Language production: >50% children +/- 1SD; some are below

Language comprehension Language expression

Who are the children we study? Bilateral cochlear implants High maternal education SES is generally high Children have high IQ and memory testing

scores Not typical of CI population, but likely provide

information on “best possible outcomes”

Bilateral Cochlear Implants Bilateral CIs provided to

growing number of patients. Goal: Improve hearing in noise,

sound localization, quality of life.

Age of bilateral activation in many clinics is 12 months or younger.

But are we providing them with the best possible input that will maximize outcomes?

-50 º

-40 º

-30 º-20 º

-10 º 10 º20 º

Studies in adults: Sound localization in Noise

Sound localization error is lower using 2 CIs compared with 1

Bilateral CIUnilateral CI

Jones et al. (Litovsky lab)

Unilateral: 77.7°

al: 6.7°

Mean RMS Localization Errors

Bilateral: 25.3°

Localization with CIs is much poorer than normal hearing listeners

Bilateral CI

Normal hearing

Unilateral CI

Unilateral: 77.7°

al: 6.7°

Mean RMS Localization Errors

Jones et al. (under preparation)

Sound Localization in 5-12 yr. olds

NH-Study1NH-Study2

BiCI (BI)BiCI (Uni)

Litovsky and Godar (2010)

Grieco-Calub and Litovsky (2010)

Bilateral

Unilateral

RMS error: Sound Localization in 5-12 yr. olds

Normal Hearing BiCI

Review; Litovsky (2011)

GAP NH vs. CI

Testing “toddlers”: (2-3 years old)Left/Right Discrimination

Orienting to sound

Grieco-Calub, Litovsky, Werner (2008)Grieco-Calub & Litovsky (2012)

Right – Left Discrimination (MAA)

Grieco-Calub, Litovsky, Werner (2008)Grieco-Calub & Litovsky (2012)

Normal Hearing

BilateralCIs

< 12 months

> 12 months

Experience withBilateral CIs

10 unableTo perform the task

10 With Uni CIs Unable to performthe task

Toddlers: Reaching for sound(Ecologically / motivating task)

StimulusWhen I hide I say…

Litovsky et al. (2012, in press)

Results All toddlers tested with the “Reaching for

sound” test were able to discriminate Left vs. Right.

However, their ability to localize was poorer than normal-hearing toddlers.

? Do they simply not have a well developed map of space?

? Are the processors not providing them with ideal cues for localizing?

Some factors affecting performance

Behind-the-ear (BTE) location of microphones

Signal processing compromises acoustic cues

Location of electrode within the cochlea

Difference in the insertion of electrodes between ears

Neural pathway degradation

Brain “Plasticity” In order for cochlear implants to be able to work, the

brain has to adapt to new information, to convert electrical signals to meaningful everyday sounds (speech, music, etc.).

Plasticity is the brain’s ability to change, re-organize, respond to new information.

Experience, plasticity……

Deaf Unilateral Bilateral

Chronological age at CI1Length of Bilateral

Experience

Hearing age

Birth(deaf)

1st CI 2nd CI

Later-onset deafnessSpatial map emerges

or re-emerges

“Plasticity” Depends on history,

etiology. Depends where in the

brain we look. More plasticity at “higher”

centers. More hard-wired at lower centers (training may be critical).

Important to get the peripheral information to be as good as it can be.

Other sources of limitations: Today’s CIs are Bilateral

Because…. The CIs in the two ears function independently. No guarantee that stimuli will activate devices such that ITDs or ILDs are preserved with fidelity

Goal: to provide Binaural hearing

Next Step: Reverse Engineering Using Research Processors

Using a Personal Digital Assistant (PDA) to load binaural software and interface with a binaural “card” for hardware (in collaboration with UT Dallas).

Research processors provided by CI manufacturers to control inputs to the two ears “at the bench”

Final note: Bottom-up & Top-down What about other sources of

variability?CognitiveExecutive functionMemory Incidental learningHow does brain plasticity

interact with these?

Misurelli and Litovsky, in prep.

Conclusions1. We are looking to close the gap between

bilateral CI users and NH binaural listeners. 2. Optimizing localization in bilaterally

implanted children may require experience with binaural cues.

3. Cognition and top-down processes may play an important role.

Thanks to the Binaural Lab

Work funded by NIH-NIDCD R01-DC003083 & R01-DC008365

Waisman Center

Univ. of WisconsinMadison

Exp. 1: Discriminating Right vs. Left Child only sees 2 holes in curtain:

+/- 60+/-45+/-30+/-15

Test at each pair to determine if child can: discriminate Left vs. Right bilaterally vs. unilaterally

Litovsky et al. (2012, in press)

Even though they can discriminate L-R, BiCI toddlers find it harder than NH toddlers

NH BiCI

Children1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

BiCINormal Hearing

Children1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

NH BiCI

BiCINormal Hearing

Litovsky et al. (2013)

Exp. 2: Localizing (9 alternative forced choice)Children with Normal Hearing

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 88.46%

RMS = 5.1

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 88.46%RMS = 5.1= 3 responses

= 1 response

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 100%

RMS = 0

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 100%RMS = 0

= 3 responses= 1 response

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 14.81%

RMS = 35.59

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 14.81%RMS = 35.59

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 96.3%

RMS = 2.89

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

= 1 response

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 83.33%

RMS = 8.66

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 83.33%

RMS = 8.66

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 96.3%

RMS = 2.89

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 96.3%

RMS = 2.89= 3 responses= 1 response

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 74.07%

RMS = 10.41

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 74.07%

RMS = 10.41

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 92.59%

RMS = 4.08

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 92.59%RMS = 4.08

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 66.67%

RMS = 10

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 66.67%RMS = 10

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 92.59%

RMS = 14.43

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 92.59%RMS = 14.43

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 33.33%

RMS = 33.17

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 33.33%RMS = 33.17

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 83.33%

RMS = 13.69

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 83.33%

COO COR COS COT

COV COW COX CPF

CPH CPK

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 88.46%

RMS = 5.1

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

= 1 response

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 100%

RMS = 0

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 100%

RMS = 0

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 14.81%

RMS = 35.59

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 14.81%RMS = 35.59

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 96.3%

RMS = 2.89

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 96.3%

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 83.33%

RMS = 8.66

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 83.33%

RMS = 8.66

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 96.3%

RMS = 2.89

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 96.3%

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

ation (

Pc = 74.07%

RMS = 10.41

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 74.07%

RMS = 10.41

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 92.59%

RMS = 4.08

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 92.59%RMS = 4.08

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 66.67%

RMS = 10

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 66.67%RMS = 10

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 92.59%

RMS = 14.43

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 92.59%RMS = 14.43

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 33.33%

RMS = 33.17

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 33.33%

RMS = 33.17

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 83.33%

RMS = 13.69

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 83.33%

CPH CPK

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 21.82%

RMS = 52.39

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 21.82%RMS = 52.39

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 37.04%

RMS = 40.52

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 37.04%RMS = 40.52

-60 -45 -30 -15 0 15 30 45 60

Target Location ( )

Pc = 11.11%

RMS = 42.62

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 11.11%RMS = 42.62

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 38.1%

RMS = 42.17

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 38.1%RMS = 42.17

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 19.44%

RMS = 37.17

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

Pc = 19.44%

-60 -45 -30 -15 0 15 30 45 60

Target Location ()

Pc = 15.56%

RMS = 43.13

-60 -45 -30 -15 0 15 30 45 60-60

Target Location ( )

= 1 response

CIEP CIEQ CIER

CIEY CIEZ CIBF

Exp. 2: Localizing (9 alternative forced choice)Children with Normal Hearing

Ruth Litovsky University of Wisconsin Madison, WI USA

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