FUNCTIONAL MRI
in MOTOR IMAGERY
JEFFREY S. ROSS, M.D.
NEURORADIOLOGY
CLEVELAND CLINIC FOUNDATION
ROSSJ1@CCF.ORG
FUNCTIONAL MRI
• BRAIN IS UNIQUE
– Strong relation between location and function
• MULTIPLE TECHNIQUES TO EVALUATE
FUNCTION
– Clinical cases (strokes, tumors, epilepsy, etc.)
– Animal lesion studies
– EEG, MEG, etc.
– Direct intraoperative electrical stimulation
– Functional imaging (PET, FMRI)
BASICS
Change in local brain activity
Change in local brain metabolism
Change in local hemodynamics
BASICS
• IMAGE DURING 2 BEHAVIORAL STATES
– Control state
– Activation state
• “DIFFERENCE” IMAGE SHOWS “ACTIVATED”
BRAIN
– Brain activated depends critically on design of task
– Tasks carefully designed to isolate function of interest
• BLOOD FLOW USED AS ENDOGENOUS
CONTRAST
BOLD FMRI basics
• BOLD: Blood Oxygenation Level Dependent
• Signal changes based on blood O2 level
– Oxyhemoglobin (HbO2) diamagnetic
– Deoxyhemoglobin (Hb) weakly paramagnetic
• Paramagnetic substance
– Causes local magnetic field heterogeneity
– Shortens T2, T2* relaxation times
– Lowers signal in tissue
BOLD effect
100% O2
Room air
Rat brain at 9 tesla (Ogawa et al MRM 14:68, 1990)
BOLD EFFECT
• BLOOD O2 LEVEL
– Blood flow
– Tissue metabolism
• NEURAL ACTIVATION
– Increase in local blood flow greater than
– Increase in local O2 extraction
– Increased capillary, venous HbO2
– More HbO2 causes increased signal
• SMALL
• DELAYED WITH RESPECT TO STIMULUS ONSET
• LASTS A FEW SECONDS
• FIELD STRENGTH DEPENDENT
BOLD EFFECT
RESTING
ARTERY
CAP
ACTIVATED
VEIN
CBF
CBV
O2 SAT
fMRI signal
• SIGNAL CHANGES OF 2-5%
• STRONGLY FIELD DEPENDENT
• LAG TIME FOR RESPONSE, AT LEAST
300 msec UP TO 4s
off
0
on
off
on
off
PROBLEMS
• IMAGE NOISE
• MOTION SENSITIVE
– Head motion under 0.5 mm can ruin data
• SILENT REGIONS
– MAKE NOTHING OF WHAT YOU DON’T SEE
• ACTIVATED REGIONS
– ACTUAL CONTRIBUTION TO COGNITIVE TASK?
• ANATOMICAL ACCURACY
– LOCALIZATION OF EXTENT OF ACTIVATION
– ASSUME ACTIVATION TAKES FORM OF DISCRETE
LOCAL INCREASE IN FLOW
PROBLEMS
• PARADIGM DESIGN
– ASSUME BRAIN IN STABLE COGNITIVE STATE
DURING MEASUREMENT
– HOW OFTEN REPEATED
– HOW EASY/HARD TO PERFORM
– NATURAL OR TIGHTLY CONTROLLED
– COGNITIVE DEMANDS
– EMOTIONS
• MACROSCOPIC LANDMARKS
– SEVERAL “SPACES” – TALAIRACH
• PRECISE TEMPORAL RELATIONSHIP
Mapping the Sensori-motor
Homunculus
TONGUE
LIP
HAND
ELBOW
SHOULDER
HIP
KNEE
ANKLE
WORD GENERATION
MOTOR IMAGERY Introduction
• Mental imagery involves rehearsing or
practicing a task in the mind with no
physical movement
• The technique is commonly utilized, and
widely advocated
• Physical foundation of imagery not well
characterized for fast, complex, automatic
motor movements such as the golf swing
LEADBETTER’S IMAGES
GOLF DIGEST, MARCH 2001
It's a great image for any golfer faced with a
pressure shot. Replay an old "tape" from your
memory bank, thinking of a past success rather
than calling up a negative memory. You'll then
have an excellent chance of duplicating the
successful shot.
Introduction
• This study evaluated motor imagery of the
golf swing, of golfers of various handicaps,
using fMRI to:
• 1) Assess whether areas of brain activation
could be defined by this technique and;
• 2) To define any association between
activated brain areas and golf skill.
Materials and Methods
• Six golfers of various handicap levels
(0,5,7,10,11,13) with evaluated with functional
MRI during a control condition and during
mental imagery of their golf swing.
• Five of the six subjects were right handed, and
play golf right handed.
• The subject with a 5 handicap (hcp) was left
handed, but plays golf right handed.
• 6 males, 24-50 years of age, average age 39 years.
Materials and Methods
• 1st person perspective, as they would
on a practice tee, with each swing
mentally occurring every 1.5-2
seconds. No preshot routine.
• Two control conditions were
evaluated, “rest” and “wall”
PARADIGMS
• REST
– subjects were told to project
themselves into a restful state, such
as sitting quietly on a beach, taking
care not to move mentally (or
physically) during the study
• WALL
– were told to imagine leaning against
a wall with their hands outstretched
and pushing against it
Materials and Methods
• Functional studies were performed on either a 1.5T
whole body (Symphony, Siemens, Erlangen) or 3T
head only (Allegra, Siemens, Erlangen) MRI
systems.
• On the 1.5T system, the body coil was used to
transmit, with a receive-only head coil collecting the
data.
• A transmit/receive head coil was used to acquire the
3T functional studies.
• Functional images : 2D multi-slice gradient echo
EPI acquisition. Sixteen slice locations were
collected every 3-4 sec with fat saturation.
RESULTS
• Vermis, SMA, cerebellum and motor regions
generally showed the greatest activation
• Little activation seen in cingulate gyrus, right
temporal lobe, deep gray matter, and brainstem
• Wall vs. golf paradigm showed generally
diminished activation across all regions
compared to the Rest vs. golf
• Decreased activation most extensively with the
better players
RESULTS
• Assuming a limit of 2% activation, 95%
confidence intervals were generated. This showed
with a 95% confidence that the following areas
were activated greater than 2%
– 13 handicap: Brainstem, Left motor, Left
sensory, Left SMA, Left temporal, Right
cerebellum, Right SMA, Vermis
– 7 handicap: Left SMA
– 5 handicap: no areas
– 0 handicap: no areas
rm
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Percent area activation, 13 handicap
averaged five series of “rest vs. golf”
14
12
10
8
Series1
6
4
2
0
R cingulate
L cingulate
R temporal
R deep grey
R frontal
R parietal
L occipital
L deep grey
L temporal
R sensory
R occipital
brainstem total
Vermis
R SMA
L SMA
L motor
R cerebellum
L cerebellum
R motor
L sensory
L frontal
L parietal
25
20
15
10
5
0
0 rest
5 rest
7 rest
10 rest
11 rest
13 rest
13 rest
11 rest
10 rest
7 rest
5 rest
0 rest
Vermis
R SMA
L SMA
L motor
R cerebellum
L cerebellum
R motor
L sensory
L frontal
L parietal
R occipital
brainstem total
R sensory
L temporal
L deep grey
L occipital
R parietal
R frontal
R deep grey
R temporal
L cingulate
R cingulate
14
12
10
8
6
4
2
0
0 wall
5 wall
7 wall
11 wall
13 wall
13 wall
11 wall
7 wall
5 wall
0 wall
Vermis
R SMA
L SMA
L motor
R cerebellum
L cerebellum
R motor
L frontal
L sensory
L parietal
R occipital
Brainstem
R sensory
L deep gray
L temporal
L occipital
R frontal
R parietal
R deep gray
R temporal
L cingulate
R cingulate
14
12
10
8
6
4
2
0
0 wall
5 wall
7 wall
11 wall
13 wall
13 wall
11 wall
7 wall
5 wall
0 wall
REST VS GOLF
13 HANDICAP
CONCLUSIONS
• Demonstrated the feasibility of
defining areas of brain activation
during imagery of a complex,
coordinated motor task
• Suggests increased activation
with increasing handicap
CONCLUSIONS
• Generally good agreement of golf swing
imagery with brain activation areas
defined in the literature including:
– Primary motor control (motor cortex)
– Imagery (parietal cortex)
– Execution areas (premotor cortex of frontal
lobe, lateral cerebellum, basal ganglia, vermis
and medial cerebellar hemispheres)
– Action planning areas (frontal and parietal
cortex, SMA, lateral cerebellum)
– Error detection (cingulate, cerebellum)
CONCLUSIONS
• Increased activation with high handicap players
could potentially relate to two effects:
– 1) that increased activation reflects a failure to learn and
become highly automatic or
– 2) that increased activation is essentially pathologic, and
related to a loss of automaticity with compensatory
increased brain activity.
• Development of automaticity is relative and can be
dynamic and reversible
• Classic example of this pathology is writer’s cramp
(focal dystonia) where the severe functional
disturbances can be explained in terms of a loss of
automaticity and an increased need for controlled
processing
• Ross JS et al. The Minds Eye: Functional
imaging of golf motor imagery. American
Journal of Neuroradiology, 24:1036-1044,
June/July 2003.
QUESTIONS?
rossj1@ccf.org