Ziyad A. MakoshiMedical Student, MBBS Undergraduate

King Khaled University HospitalKing Saud University, KSA

What is Movement? Balance? Posture?

Frontal Lobe

Parietal Lobe

Secondary Motor Cortex

Initiating

Planning

Primary Motor Cortex

“The human brain, then, is the most complicated

organization of matter that we know” – Issac A.

MOVEMENT

THE EFFERENCE COPY

F o r w a r d

Supplementary Motor Area

Primary Motor Cortex

Musculoskeletal

System

Efference Copy

M o v e m e n t

Motor Command

1

2

3

Planning

Initiating

Directing

MODEl

SMA PMC Muscles (Movement)

Efference

Copy

Motor Comma

nd& other

areas

Transcranial Magnetic Stimulation (TMS)

Hypothesis

SMA plays a significant role in anticipatory motor planning.

Questions

Does this occur? At what time?

The Experiment

Tynan ^_^

Auditory cue

Infrared sensor

Platform

Release button

Chin rest

Mass

Press button

Platform falls

Arm displaced downwards

Infrared cameras measure amplitude of displacement

Conditions

TMS SITE

Control SiteOccipital lobe

SMA Site

PLATFORM

Experimenter (Passive)

Subject (Active)Subject does not

anticipate the fallBaseline

Subject anticipates the fallAmplitude should be less

First 20 blocks

(no TMS)

Second 70 blocks

(TMS)

I II

Variables

Cue

Platform (RT)

TMS

0 ms

Amplitude

TMS Delay (ms)

0 50 100 150 200 250 300

-5

-4

-3

-2

-1

0

1

2

3

4

5V1

SMA

Cha

nge

in A

mpl

itude

(cm

)

Active (w/o TMS)

Passive

Results

Cue

TMS

0 ms

Amplitude

100 ms

X axis

Y axis

TMS - RT Delay (ms)

0100200300400500600

Cha

nge

in A

mpl

itude

(cm

)

-5

-4

-3

-2

-1

0

1

2

3

4

5

V1SMA

Passive

Active (w/o TMS)

*

*

Results (Cont.)

Cue

TMS

200 ms

Amplitude

100 ms

X axis

Y axis

Platform (RT)

Conclusion

Taken together, our results show that the SMA plays an important role in forming and/or using an efference copy during anticipatory motor planning.

The fact that the effects of TMS were largest at the earliest stimulation times indicates that the SMA makes its contribution to this process well before (i.e., 400-500ms) movement onset.

Future Studies

Focus on the earlier time in the

planning process when the

effect of TMS was most obvious.

Develop a task to better

establish the occurrence of an

efference copy.

Research other areas that might

contribute to efference copy.

cknowledgmentsA

Dr. Paul van

Donkelaar &his lab ,

Robert, Tynan.

SPUR , Dr. Peter

O’Day, &Chelsie Fish

SPUR Interns

University of Oregon

Thank You