Multimodal Neuroimaging Training ProgramNIRS module

Anna ManelisDepartment of Psychology, CNBC

Carnegie Mellon University

Faculty Instructor: Theodore Huppert, PhDTechnical Adviser: Nancy Beluk

July 14, 2011

NIRS

• portable

• relatively non-invasive

• low cost

• has low sensitivity to subjects’ motion

• able to measure both oxy- hemoglobin and deoxy- hemoglobin as a function of near-infrared wavelengths

CW6 system

Registration

Find a right spot

detectorssources

4 experiments

• Median nerve stimulation (2 subjects)

• Finger tapping (1 subject)

• Words encoding and recognition (1 subject)

• Working memory (2 subjects)

the measurements were taken at two wavelengths (690nm and 830nm).

Finger tapping

15s on + 15s off

5 blocks

Right hand

Unilateral probe

QuickTime™ and a decompressor

are needed to see this picture.

Finger tapping

sources

detectors

detectors

Finger tappingLeft motor cortex

ΔOD – changes in optical Density at 830 nm

Raw data

Optical density = -log (I1/I0)

0 50 100 150 2000 50 100 150 200

Finger tappingLeft motor cortex

hp=70s, GF=2s

0 50 100 150 200

Finger tappingLeft motor cortex

hp=70s, GF=2s

0 50 100 150 200

Finger tappingLeft motor cortex

hp=70s, GF=2s

0 50 100 150 200

Memory Studies

Right

Verbal memory

690nm

830nm

encoding recognition

0 50 100 150 200 0 50 100 150 200time (sec) time (sec)

Verbal memoryencoding recognition

HbRHbO

HbT

0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70time (sec) time (sec)

N-back predictionsfMRI results

Owen et al., 2005 (HBM)

N-back load effect

1-back

2-back

3-back

0 10 20 30 40 50 60 70

time (sec)

Summary

NIRS can detect changes in brain activity in various tasks that include simple sensory-motor and higher cognitive functions tasks

Three types of noise in NIRS data:•instrument noise

- sometimes difficult to detect- not much support from the companies- may have different distribution across channels and wavelengths

•physiological noise

•experiment error - cap motion (especially problematic for bilateral

caps)- cap placement

Limitations

690 nm 830 nm

690 nm vs. 830 nm

Noise in the data

Three types of noise in NIRS data:•instrument noise

- sometimes difficult to detect- not much support from the companies- may have different distribution across channels and wavelengths

•physiological noise

•experiment error - cap motion (especially problematic for bilateral

caps)- cap placement

Limitations

Methods for data analysis and registration are not well developed (i.e., work in progress)

NIRS is sensitive to • the changes in the scalp thickness over time • between-subject variability within the brain stuctures

Limitations

Acknowledgements

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Seong-Gi Kim, PhDBill Eddy, PhDTheodore Huppert, PhDNancy BelukTomika CohenMNTP Faculty, Staff, and Teaching AssistantsUniversity of Pittsburgh Medical CenterCarnegie Mellon Center for Neural Basis of CognitionNIH R90DA023425T32-MH019983-12