Post on 18-Dec-2015
Deficits in Spatial Cognition After TBI Revealed By Virtual Morris Water Maze
R.W. Skelton & S.P. Ross, Psychology, University of
Victoria, Victoria, BC, CANADA
2Premises
Traumatic brain injury (TBI) damages many neural structures and impairs many cognitive functions, including:
Hippocampus, Episodic memory, Spatial memory. Animal research shows Morris water maze
(MWM) useful for measuring deficits in spatial memory and hippocampal function.
Previous study showed that survivors of TBI show deficits in Virtual MWM
Present study uses more advanced 3D environment
And distal cues for orientation
3Methods
Participants TBI: 14 (11M, 3F)
23-67 years old, ½-48 years post-injury (9 MVA) Non-Injured: 12 (7M, 5F), 19 – 52 years old
Virtual MWM Built with Unreal® Editor, shown on desktop
system Large (~40 m) arena (circus ring) with 2 m circular
platform Large square room with windows and world outside
Room and world has “cardinal” orientation (North-South etc)
4Methods
Trials Free time for orientation, mapping and
joystick practice 4 with platform visible (varying locations) 10 with platform invisible (until tread upon) in
fixed location, from varying start locations 1 Probe (no platform)
Measures Distance and Latency (measured with
TRAM®) Dwell time in correct quadrant on Probe trials Spatial Score: z-score average of invisible
platform trial and probe trial data
5Methods
Virtual MWM requires combinations of distal and proximal cues for navigation (not just single cues or landmarks)
Views showing visible platform and outside scenery
Views of the arena, room and visible platform
6Methods Trials start from 4 different positions.
Visible platform
Views of Arena from the 4 start positions.
Invisible platform
7Results: Learning Trials
Participant with no injury quickly learns to find the invisible platform
Participant with brain injury takes longer to learn to find the platform
Sample Data
8
Distance
0
100
200
300
400
500
600
700
800
900
1 2 3 4 5 6 7 8 9 10 11 12 13 14 Avg 6-14Trial
Pa
th le
ng
th
TBI
Control
Visible platform Invisible platform
Results: Learning Trials
TBI slows acquisition of platform location: Path lengths are longer
Group Data
Sample Individual
Data
TBI
Control
9
0
5
10
15
20
25
30
35
40
45
Lat
ency
(s)
Visible Invisible
Control
TBI
0
2
4
6
8
10
12
14
16
18
20
Sp
ee
d
Visible Invisible
Control
TBI
Results: Learning Trials
Groups show large differences in ability to locate invisible platform
Groups show only small differences in speed of movement
0
50
100
150
200
250
300
350
400
450
500
Dis
tan
ce
Visible Invisible
Control
TBI
0
10
20
30
40
50
60
70
80
90
100
Eff
ica
cy
Visible Invisible
Control
TBI
Latency
Distance
Speed
Efficacy
10Results: Probe Trials
Those with TBI showed poor searches when platform absent.
Control participant closest to group
meanParticipant with TBI
closest to group mean0
10
20
30
40
50
60
70
80%
Co
rrec
t (D
wel
l Tim
e)
CorrectQuadrant
Quadrant/RingDiscrimination
Control
TBI
11Results: Group Differences
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Speed
Latency
Distance
Efficacy
Corr Quad dw%
Quad/Ring discr
Spatial Score
Effect Sizes (Cohen's d)
Large effects
Effect sizes reveal that most measures of spatial navigation show large differences between TBI and Controls
12Conclusions
Virtual MWM reveals deficits in spatial navigation after TBI.
Some measures show bigger effects. Study replicates previous finding.
Impairment after TBI not due to primitive 3D rendering.
Useful for studying TBI deficits and functions of human
hippocampus.