Neurofeedback Peak Neurofeedback Peak PerformancePerformance
in Microsurgeryin Microsurgery
Tomas RosDept. of PsychologyGoldsmiths CollegeLondon
Conjunct COST B27 and SAN Scientific Meeting, Swansea, UK, 16-18 September 2006
Neurofeedback Peak Neurofeedback Peak PerformancePerformance
in Microsurgeryin Microsurgery
Tomas RosDept. of PsychologyGoldsmiths CollegeLondon
RationaleRationale• EEG peak-performance enhancements in:
cognition sport artistic ability
• microsurgical technique uniquely combines the mental and physical skills present in such fields
• we assessed the training effects of 2 widespread neurofeedback protocols to the novel area of
eye microsurgery
2 Protocols
Research Evidence:
• SMR-Theta training can lead to improvements in attention and memory (Vernon et al. 2003, Egner & Gruzelier 2004)
• Alpha-Theta has been shown to induce relaxation and reduce anxiety, as well as enhance artistry (Egner & Gruzelier 2003, Raymond et al. 2005)
Neurofeedback Training
• visual feedback• SMR, theta, high beta SMR (12-15 Hz), theta (4-7 Hz), high beta (22-30 Hz)• referential at Cz
• auditory feedback only• alpha, theta alpha (8-11 Hz), theta (4-7 Hz)• referential at Pz
Alpha-Theta:
SMR-Theta:
Neurofeedback Training
• AT alpha: babbling brook theta: ocean wave
• SMR: “Space race” (3-way)
• ProComp + amplifier• Neurocybernetics EEGer• 160 Hz sampling, 0.5 s filter• 3-min autothreshold
Equipment:
Feedback:
Neurofeedback Training
• approx. 1 session / week
• 8 sessions in TOTAL
• 3 min baseline (period 1)
• approx. 25 min session
Duration:
Rate:
Study DesignStudy Design
• randomised, single-blind, controlled
• 2 neurofeedback protocols
Alpha-Theta (AT) N=10SMR-Theta (SMR) N=10
• 1 wait-list control group N=8
TOTALN=20
• LOCATION: Western Eye Hospital, London
• 20 trainee surgeons (NHS house officers & registrars)
• 10 males, 10 females
• mean age 33.5, SD 5.12
TOTALN=20
ControlN=8
Training onlyN=12
TOTALN=20
ControlN=8
Training onlyN=12
W A I T (~2 months)
TOTALN=20
ControlN=8
Training onlyN=12
W A I T (~2 months)
ATN=4
SMRN=4
TOTALN=20
ControlN=8
Training onlyN=12
SMRN=6
ATN=6
W A I T (~2 months)
ATN=4
SMRN=4
AssessmentAssessment
1) MOOD questionnaire Spielberger’s state & trait anxiety (pre performance self-report)
2) SURGICAL performancemulti stage surgical task on artificial-eye
(~10 min video recording from two angles)
3) ATTENTION test‘Attention Network Test’, or ANT
(15 min reaction time test on computer)
CONTROLassessment
PREassessment
POST assessment
WAITLIST GROUP(N=8)
W A I T
N F B
TRAINING ONLYGROUP(N=12)
CONTROLassessment
PREassessment
POST assessment
TRAININGpre / post
(N=8)
W A I T
N F BTRAININGpre / post(N=12)
CONTROLpre / post
(N=8)
WAITLIST TRAINING ONLY
Test-retest intervalsTest-retest intervals
CSMRAT
140
120
100
80
60
40
20
0
tim
e (d
ays)
Error bars: +/- 1.00 SE
• One-way ANOVA: no significant differences between groups
p=0.40
RESULTSRESULTS
NFB training spectra
1 2 3 4 5 6 7 8
Session
0.96
0.98
1.00
1.02
Alpha-Theta (AT) training
AVERAGE for all AT subjects
1 2 3 4 5 6 7 8 9 10
Period
0.95
0.98
1.00
1.03
1.05
Th
eta
/ Alp
ha
rat
io
p<0.01 p<0.01
SMR-Theta training
1 2 3 4 5 6 7 8
Session
0.50
0.55
0.60
0.65
AVERAGE for all SMR subjects
1 2 3 4 5 6 7 8 9
Period
0.57
0.58
0.59
0.60
0.61
SM
R/T
het
a ra
tio
p<0.01p<0.01
RESULTSRESULTS
Surgical Technique
Judges’ ratings
• scored independently
• score averaged over 2 judges
• each judge was blind to:
presentation order
subject identity
Task description Sub-step Score
1A Design of the side port
Correct stabilization of globe opposite cornea to corneal incision
1
Correct angle of blade parallel to iris
2
Correct length (1/2 length of 15° blade)
3
Correct position / meridian / regularity (just on clear corneal side of limbus)
4
Filling AC with viscoelastic evenly
5
1B Avoidance of complications of creating the side port
No sudden collapse of AC 1
No injury to the iris 2
No injury to the capsule 3
No injury to the cornea 4
Overall Technique
post
pre
CSMRAT
1.00
0.80
0.60
0.40
0.20
0.00
tech
nic
al s
kill
sco
re (
%)
*
• Paired Wilcoxon: significant increase in SMR group
p=0.038
p=0.26p=1.0
Task Technique
wound
knotrrhexis
phaco
sideport
CSMRAT
20
15
10
5
0
-5
tech
nic
al s
core
ch
ang
e (%
)
*
• Paired Wilcoxon: significant increase in SMR group
p=0.018
6.2 %
484437332925211713951
Video number
1.00
0.90
0.80
0.70
0.60
Ove
rall
sco
re (
%)
JUDGE B
JUDGE A
• ICC: 0.85 for SMR performances, 0.64 for ALL performances
Inter-rater reliability
RESULTSRESULTS
Performance Speed
Performance Speed
• objective data calculated from videos
OVERALL time = TASK time + PAUSE time
OVERALL time: start to finish
TASK time: spent in contact with eye
PAUSE time: spent otherwise
Overall time
CSMRAT
12
11
10
9
8
7
Mea
n t
ime
(min
)
postpre
• Paired T-test: marginal decrease in AT & SMR group
p=0.16
p=0.20
p=0.84
15 %
Task time
CSMRAT
10
9
8
7
6
5
Me
an
tim
e (
min
)postpre
*
• Paired T-test: significant decrease in SMR group
p=0.021
25 %
p=0.26p=0.90
Pause time
CSMRAT
5
4
3
2
1
me
an
tim
e (
min
)
post pre
• Paired T-test: no significant changes in groups
p=0.56p=0.50
p=0.72
Individual Tasks
phaco
knotrrhexiswound
sideport
CSMRAT
2.5
0
-2.5
-5
-7.5
tim
e c
ha
ng
e (m
in)
*
• Paired T-test: significant decrease in SMR group
p=0.018
6 %
Subjective vs objective scores
• Correlation between subjective (technique) and objective (times) performance measures
• Positive changes in overall technique were coupled to reductions in total task time (R= -0.700, p=0.036)
RESULTSRESULTS
Attention Network Test
A N T Posner et al (2002, 2004)
• measures 3 separate attentional networks (alerting, orienting, and conflict)
• based on earlier functional studies (e.g. Posner & Peterson, 1990)
Attention Network Test (A N T)
conflictorientingalerting
CSMRAT
20
10
0
-10
-20
-30
Eff
icie
ncy
ch
an
ge
( m
s )
p=0.05
p=0.095
• Paired T-test: significant orienting decrease in SMR group
25 %
RESULTSRESULTS
State & Trait Anxiety
• filled in prior to each assessment
• 2 parts:STATE anxiety
how subject feels at that moment
TRAIT anxiety how subject felt in the last week
Spielberger’s Anxiety Inventory
Spielberger’s Anxiety Inventory
CSMRAT
50
40
30
20
10
0
mea
n A
NX
IET
Y s
core
postpreSTATE
• Paired Wilcoxon: no significant change within groups
p> 0.05
Spielberger’s Anxiety Inventory
• Paired Wilcoxon: significant decrease in SMR group
CSMRAT
50
40
30
20
10
0
mea
n A
NX
IET
Y s
core post
preTRAIT *
p=0.017
10 %
RESULTSRESULTS
NFB / surgical performanceassociations
AT training vs performance
• Successful within-session AT training correlated significantly with overall technique (R= 0.638, p=0.047)
• Between-session AT training marginally correlated with overall time of performance (R=-0.523, one tailed p=0.060)
• Successful within-session SMR-training ratio was associated with increases in total pause time (R=0.584, p=0.077)
• Pause time was also negatively correlated with task time (R= -0.251)
• A significant partial correlation of within-session learning and pause time was obtained (R=0.703, p=0.035)
SMR training vs performance
X-axis: SMR group split into two equal halves.
GOOD performers were top five subjects with greatest reductions in surgical task time,
BAD performers were bottom half
Y-axis: mean SMR-theta ratio
BARS: between first & second half of all periods between first & second half of all sessions
SMR training vs performance
GOOD performersBAD performers
0.60
0.40
0.20
0.00
SM
R-T
he
ta r
atio
Periods 6 - 9Periods 2 - 5
PERIOD ratio vs performance
• Paired T-test: no significant change within groups
p> 0.05
GOOD performersBAD performers
0.60
0.40
0.20
0.00
SM
R-T
he
ta r
atio
Sessions 5 - 8 Sessions 1 - 4
*
• Paired T-test: significant decrease in BAD performers
p=0.001
SESSION ratio vs performance
10 %
ConclusionConclusion&&
SummarySummary
Summary
SUBJECTIVE MEASURES
•technique improvement in SMR group p=0.04
•trait anxiety reduction in SMR group p=0.02
OBJECTIVE MEASURES
•task time reduction in SMR group p=0.02
•SMR/theta lowered in BAD performers p<0.01
•SMR learning/pause time correlation p=0.03
Model
The results therefore remain in line with previous research on trained enhancement of SMR activity:
• successful reduction of impulsiveness & hyperactivity (Lubar and Shouse 1976)
• enhancement of attention more generally (Sterman 1996; Egner and Gruzelier 2004)
Conclusions
SMR training:
significantly enhances surgical technique
25% less time of instrument contact with eye(can improve post-operation recovery)
AT training:
marginally reduces total surgery time(despite low training efficacies)
AcknowledgementsAcknowledgements
All the surgeons
Prof. John Gruzelier, Merrick Moseley, Philip Bloom and Larry Benjamin
Royal College of Ophthalmology
Dr. Lesley Parkinson
