An Auditory Cortex Site Critical to Discrimination Learning

Adam Duvel and Mike Gabriel

Neural Pattern Analysis

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Auditory Cortical Lesions and LearningAuditory Cortical Lesions and Learning

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Auditory Cortex Lesions and TIAAuditory Cortex Lesions and TIA

Patterned Neurons Develop Patterned Neuronal Activity

Bruce Wheeler with

Deborah Leckband

Correlated Neuronal Activityfrom Neuronal Networks

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Are Neurons in Patterns More Active?

A. Patterned Networks Have Greater ActivityWithout Patterns: 1% ± 3% active electrodes

0.43 ± 0.35 Hz spike rateWith Patterns: 16% 12% active electrodes

2.13 ± 3.0 Hz spike rate

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B. Activity Increases with Cell Density

PatternedNeuron Cultures

Well Patterned

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Glia Develop More Rapidly On Patterns

Green – GFAP -- GliaRed –Neurofilament

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14 days in culture

22 days in culture

Evaluation of a Binaural FMV Beamforming Algorithm in

NoiseJeffery B. Larsen, Charissa R. Lansing,

Robert C. Bilger, Bruce Wheeler, Sandeep Phatak, Nandini Iyer, Mike Lockwood, William

O’Brien, Doug Jones, and Albert S. Feng

Research supported by NIH grant #DC04840

INTRODUCTION

A Frequency Banded Minimum Variance (FMV) algorithm has been developedPreliminary investigations with the FMV in simulation have been promisingEvaluation of the FMV in a multi-source environment is needed to demonstrate its effectivenessThe primary question of this study is: How much benefit from the FMV is obtained in noisy environments beyond that provided by directional microphones alone?

Setup of current preliminary investigation - Experiment #1

• Dependent variables– SRT in quiet and in noise with spondaic

words– SRT in quiet and in noise with HINT

sentences (Nilsson, Soli, & Sullivan, 1994)– Subject rated intelligibility of SIR passages

(Cox & McDaniel, 1989) at a -4 dB SNR

• 5 listeners w/ NH (20 - 40 years old) and 9 w/ SNHL (53 to 81 years old)

Setup #1

*Target Computer

Real-time system

Probe mic system

Cardioid mics

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* Reversed speech of four talkers speaking R-SPIN sentences at -40°, -20°, 20°, and 40° from target at 0°

CD player

Setup of current preliminary investigation - Experiment #2• Dependent variables

– SRT in quiet and in noise with HINT sentences (Nilsson, Soli, & Sullivan, 1994)

– Percent Correct of Keywords for CST Passages (Cox, Alexander, & Gilmore, 1987) at a 0 dB SNR

• 5 listeners w/ SNHL (65 - 80 years old) • Use of speech-shaped cafeteria noise

(Ricketts & Dhar, 1999) as jammer• Novel spacing and levels of jammers

CONCLUSIONS• FMV algorithm provides benefit across:• Competing signal types

– Speech shaped cafeteria noise and reversed speech• ESSENTIALLY EQUAL BENEFIT IN EACH

• Response Tasks– Intelligibility ratings - 50% higher for FMV than DM– Speech recognition - 36% improvement in WRS– Fixed and variable SRT measures

• 6 TO 8 dB OF SRT IMPROVEMENT OVER DIRECTIONAL MICS ALONE FOR NORMAL HEARING LISTENERS

• 8 TO 13 dB OF SRT IMPROVEMENT FOR LISTENERS WITH SNHL OVER DIRECTIONAL MICS ALONE DEPENDING UPON LOCATION OF JAMMERS

CONCLUSIONS (cont.)• Auditory Scenes

– Setup #1 - jammers equal at +20º and +40º (Thanksgiving table scene)

• VARIABLE SRT IMPROVEMENT OVER DIRECTIONAL MICS FOR LISTENERS WITH SNHL WAS 8 TO 11 dB

– Setup #2 - Closest jammer at +20º was more intense than other three jammers at -80º, -40º, and +60º (4th of July picnic scene)

• MEAN VARIABLE SRT IMPROVEMENT OVER DIRECTIONAL MICS FOR LISTENERS WITH SNHL WAS 13 dB (range of 8 to 19 dB across listeners)

FUTURE DIRECTIONS• Direct comparison of FMV with

commercially available hearing aids with technology for listening in noise

• Continued assessment of performance in different noise source configurations and reverberation times

• Comparison of speech intelligibility performance with subjective measures of quality

• Comparison of human performance with engineering metrics

Direct Evidence for Modular Binding Interactions between Cell Adhesion Molecules

The Structures of Many Adhesion Proteins Consist of Multiple Tandem Repeats of

Similar Domains

How Does This Modular Architecture Impact Protein-

mediated Intercellular Adhesion?

Cadherins Mediate Cell-Cell Adhesion in All Soft Tissue

• Cadherin extracellular regions comprise 5 similar domains.• Adhesion was predicted to involve only the outermost domain

The Surface Force Apparatus was used to Quantify the Force-Distance Profiles

Between Cadherins on Opposed Surfaces

Force-distance measurements show that cadherin binds in any of three different, antiparallel alignments.

Adhesion involves multiple domains.

Multiple binding interactions may facilitate the sequential assembly

of tight cell-cell junctions.

Sequential interactions impede the abrupt failure of adhesive

junctions under force.

Cadherin monolayers detach in an unusual way

Conclusions

• Cadherin binds in multiple, antiparallel alignments

• This is a consequence of the modular domain structure of the cadherin extracellular region

• These multiple binding interactions may (1) facilitate the self-assembly of adhesive junctions and (2) impede their abrupt failure under force.