Awakening the Auditory System: Binaural Benefit Revisited

6th International Pediatric Audiology Conference: Dec. 9. 2013

Awakening the Auditory

System: Binaural Benefit

Revisited

Blake C. Papsin

http://www.google.ca/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=qouCRfcqXb-DWM&tbnid=hMIhvOYW5gmkYM:&ved=0CAUQjRw&url=http://edtechmarketplace.com/Listing/Index/Classroom_Equipment__Hardware/Classroom_Amplification/7303/117&ei=NnSbUqKCEpOFoQSVwoCABA&bvm=bv.57155469,d.cGU&psig=AFQjCNEycINXogtanE8CwvvMQfcg8BWkMg&ust=1386005893023364

Cochlear Implant Team 2013-2014

Gina Goulding

Naureen Sohail

Laurie MacDonald

Patt Fuller

Adrian James

Mary Lynn Feness

Pat Di Santos

Nancy Greenwald-Hood

Susan Druker

Blake Papsin

Vicky Papaioannou

Karen Gordon

Sharon Cushing

Valerie Simard

Rebecca Malcomson

Joelene Huber

Gillian Lieberman

Stephanie Jewell


Introduction

plasticity and evolution

feature extraction

the senses

stereoscopy/binaural hearing

awakening the auditory system


Plasticity Evolved

Biston betularia f. typica Biston betularia f. carbonaria


Human = Information Processor

olfaction

vision

motor skill

audition

linguistic ability

executive function



olfaction

vision

motor skill

audition

linguistic ability

executive function



olfaction

vision

motor skill

audition

linguistic ability

executive function



IQ = 107 IQ = 7

http://wzus1.ask.com/r?t=a&d=us&s=a&c=p&ti=1&ai=30751&l=dis&o=15527&sv=0a5c4241&ip=ae76fb47&wz_cu=0&u=http://wolfman136.tripod.com/sitebuildercontent/sitebuilderpictures/brain.jpeg



IQ = 107 IQ = 7

http://wzus1.ask.com/r?t=a&d=us&s=a&c=p&ti=1&ai=30751&l=dis&o=15527&sv=0a5c4241&ip=ae76fb47&wz_cu=0&u=http://wolfman136.tripod.com/sitebuildercontent/sitebuilderpictures/brain.jpeg


Reduced

activity

Activity no

longer reduced

Lee, et al., Nature, 2001

Auditory Cortex in Silence


Auditory Plasticity (Learning)

↑ representation of 8-16 kHz octave band

(Stanton & Harrison 1996)

11


Capitalizing on Plasticity

Age (months)

0 10 20 30 40 50

IT-M

AIS

score

(%

)

0

20

40

60

80

100

6-12 months

12-18 months

19-23 months

Normal hearing

6-12 months


Ongoing Plasticity

adult map reorganization reported:

If animal is trained to attend to the stimulus

13

(Polley, Steinberg & Merzenich, 2006)


The Three Questions

do I run from it?

do I eat it?

do I mate with it?


Feature Extraction - Senses

extract data

collect data

assemble data


Sensory Reassembly

illusory

reassemble the

world – most

probable state


Sensory Reassembly

illusory

reassemble the

world – most

probable state


Senses

illusory

reassemble the

world – most

probable state


Vision and Audition

fundamentally different

separate pathways

temporal relationships


Vision and Audition


separate pathways


lateral geniculate nucleus


Vision and Audition


separate pathways


visual time

Auditory time

d

e

c

i

s

i

o

n


Feature Extraction

saccades scan visual

environment


Vision and Audition


separate pathways


visual time

Auditory time

d

e

c

i

s

i

o

n


Auditory Processing

must process

environment in

one pass

extract

identify

categorize

Auditory System


Importance of Stereoscopy

the slight differences between the two

eyes define orientation in space



Development of Stereoscopy

Hubel and Wiesel

patched one side

= all input neurons to one eye

patched both sides

= all inputs neurons active


Can You “Patch” an Ear?

paths cross early

hearing occurs in

utero

conductive loss

models

lateral lemniscus


You Can “Patch” an Ear!

paths cross early

hearing occurs in

utero

conductive loss

models


And You Can “Unpatch” an Ear!

paths cross early

hearing occurs in

utero

conductive loss

models


Studying Binaural Perception




Lateralization Index = (R-L)/(R+L)


Wong et al. IEEE (2010)

Reorganization of Auditory Cortex

-50 -40 -30 -20 -10 0 10 20 30 40 50

Normal

Simultaneous

Short Delay

Long Delay

Lateralization %

Particip

an

t G

ro

up

Lateralization of Cortical Responses by Stimulus Side

Left/CI-2 Stim

Bilateral

Right/CI-1 Stim

Left cortex Right cortex

* *

*

* P<0.05

Long Delay

(> 2 years)

Short Delay

(< 1.5 years)

Simultaneous

Normal

Hearing

Lateralization of auditory activity (%) Gordon et al. Brain (2013)

Reorganization of Auditory Cortex

-50 -40 -30 -20 -10 0 10 20 30 40 50

Normal

Simultaneous

Short Delay

Long Delay

Lateralization %

Particip

an

t G

ro

up

Lateralization of Cortical Responses by Stimulus Side

Left/CI-2 Stim

Bilateral

Right/CI-1 Stim

Left cortex Right cortex

* *

*

* P<0.05

Long Delay

(> 2 years)

Short Delay

(< 1.5 years)

Simultaneous

Normal

Hearing

Lateralization of auditory activity (%) Gordon et al. Brain (2013)


Summary

sequential bilateral cochlear implantation

allows asymmetric auditory development

compromises binaural processing in the auditory

cortex


Summary

simultaneous bilateral cochlear implantation

promotes symmetric auditory brainstem

development

protects the auditory cortex from reorganized

lateralization


There is a Bilateral Advantage


...But Then it Disappears!

Jewell et al. In Press


CI1

bett

er

CI2

be

tte

r

Asymmetric Speech Perception

Jewell et al. In Press


Ben

efi

t D

etr

imen

t

Asymmetry & Bilateral Benefit

Absolute Difference Between Ears (%) Jewell et al. In Press


Signal Noise Noise Signal

Noise Signal Signal Noise

Binaural Hearing


Children Need Binaural Hearing


Calculation: spatial unmasking

(noise at 0°) vs. (noise at 90°)


Calculation: spatial unmasking

(noise at 0°) vs. (noise at 90°)


0

1

2

3

4

5

6

7

8

9

10

11

sequential simultaneous normal

Sp

ati

al u

nm

as

kin

g S

NR

(d

B)

Noise moved to 1st implanted ear

Noise moved to 2nd implanted ear

Bilateral CI Bilateral CI

Benefits of Simultaneous Bilateral Hearing

P>0.05 P=0.001

Chadha et al. Otol Neurotol (2013)

Results: Inter-aural/implant Level Differences

0

20

40

60

80

100

Left +20 dB +10 dB 0 dB -10 dB -20 dB Right

Res

po

nse

Rat

e

ILD Condition

Normal Hearing)

L

R

0

20

40

60

80

100

CI2 +20 CU+10 CU 0 CU -10 CU -20 CU CI1

Res

po

nse

Rat

e

ILD Condition

CI - Sequential

CI1

CI2

Salloum et al. Ear & Hearing (2010)

Results: Inter-aural/implant Level Differences

0

20

40

60

80

100

Left +20 dB +10 dB 0 dB -10 dB -20 dB Right

Res

po

nse

Rat

e

ILD Condition

Normal Hearing)

L

R

0

20

40

60

80

100

CI2 +20 CU+10 CU 0 CU -10 CU -20 CU CI1

Res

po

nse

Rat

e

ILD Condition

CI - Sequential

CI1

CI2

0

0.2

0.4

0.6

0.8

1

Left +20CU

+14CU

+10CU

+6CU

+2CU

0 -2CU

-6CU

-10CU

-14CU

Right

Response R

ate

ILD Condition

CI - Simultaneous

L

R

Salloum et al. Ear & Hearing (2010)

Deighton et al. In Press (2013)

Results: Inter-aural/implant Timing Differences

0

20

40

60

80

100

Res

po

nse

Rat

e

ITD Condition

Normal Hearing

L

R

0

20

40

60

80

100

Res

po

nse

Rat

e

ITD Condition

CI-Sequential

CI2

CI1

Results: Inter-aural/implant Timing Differences

0

20

40

60

80

100

Res

po

nse

Rat

e

ITD Condition

Normal Hearing

L

R

0

20

40

60

80

100

Res

po

nse

Rat

e

ITD Condition

CI-Sequential

CI2

CI1

0

0.2

0.4

0.6

0.8

1

+2000US

+1000us

+400us

0 -400 us -1000us

-2000us

Response R

ate

ITD Condition

CI - Simultaneous

L

R


Increased Effort & Increased P2 Amplitude

0

500

1000

1500

2000

2500

3000

3500

4000

Cochlear Implant Users(n=24)

Normal Hearing Peers(n=23)

Re

acti

on

Tim

e (

ms)

Auditory Auditory-Visual

Increased reaction time - emotions in speech

** ** p<0.01

Hopyan et al. Child Neuropsychology (2009)

P2

P1

N1

Tremblay et al. Clinical Neurophysiology (2009)

P2 Amplitude after auditory training

P2

Jiwani et al. Clinical Neurophysiology (2013)

Gordon et al. Frontiers in Auditory Cognitive Neuroscience (2013)


Reassembling the Auditory

Environment


Summary

aggressive bilateral cochlear stimulation

promotes:

symmetric auditory brainstem development

spatial unmasking

binaural processing

does not result in improved speech perception

in test conditions


Edge of the Envelope

auditory cortex develops “normally” with

bilateral stimulation

short period of deprivation (in children)

study children implanted with short periods of

deprivation

asymmetric hearing loss

unilateral hearing loss

Toronto, Canada October 15-19, 2014

Health & Medicine

Awakening the Auditory System: Binaural Benefit Revisited