Download Report

Memory for temporal information during spatial navigation
Iva
1,2
Brunec ,
Jason
1,2
Ozubko ,
1,2
Moscovitch ,
Morris
Morgan
1,2
Barense
(1) Department of Psychology, University of Toronto; (2) Rotman Research Institute, Baycrest Centre
Introduction
• Explore participants’ memory for time in a
spatial navigation task with closely
controlled spatial and temporal parameters
• How good is our capacity for temporal
pattern separation?
• What is the relationship between memory
for temporal duration and spatial location?
• Is information about time encoded
automatically or does it require a rich sense
of re-experiencing an event?
Re-experience/Know/New
All 12 intersections + 12 new
previously unseen intersections
from the same area of the city.
Participants respond R/K/N and
provide a confidence judgment.
Temporal duration
discrimination
All 12 intersections shown pairwise. Participants respond
Left/Right and provide a
confidence judgment.
Distance discrimination
All 12 intersections shown pairwise. Participants respond
Left/Right and provide a
confidence judgment.
Temporal Duration Discrimination
• Overall proportion correct: 0.6 (SD = 0.48)
Proportion Correct per Temporal
Interval
1
*
0.8
0.7
*
www.PosterPresentations.co
m
*
0.8
*
0.7
0.6
0.5
0.4
0.6
0.5
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0
0
1
2
3
4
5
6
7
8
9
10
Difference in seconds between compared pair
Re-experience vs. Know
1
0.9
*
0.8
0.6
0.5
RESEARCH POSTER PRESENTATION DESIGN © 2012
1
0.9
0.7
• 7 repetitions of time-constrained passively
guided navigation in a virtual rendering of
the city of Chicago, USA
• Stops in 12 intersections, each associated
with a different temporal duration (range 112 seconds).
Proportion Correct per Degree of
Spatial Separation
*
* sign. above chance at p < 0.05
Design and Stimuli
• Overall proportion correct: 0.84 (SD = 0.34)
0.9
Participants
• 14 participants (6 female)
• Average age 19.2 (SD = 2.5) years
• Average Santa Barbara Sense of Direction
Scale score 4.2 (SD = 2.0)
Distance Discrimination
*
0.4
0.3
0.2
0.1
0
Re-experience
Know
11
• Spatial information is encoded much more
readily than temporal duration information.
Memory for time appears to be more
sensitive to interference and requires a
greater degree of separation. This
suggests that temporal deficits might
precede spatial deficits in disorders such
as dementia
• Reliable temporal duration discrimination
requires a rich sense of re-experiencing
and is significantly lower when participants
report ‘knowing’ an intersection with little
associated perceptual and spatial detail
• While hippocampal time cells may track
time continuously, this information may only
be available to conscious evaluation when
the memory trace for the spatiotemporal
context is strong and the subjective
experience is vivid.
Future Directions
Results
Proportion
Aims & Questions
Summary and Conclusions
• Participants complete 7 repetitions of the same route where each of the 12 intersections is
associated with a unique temporal duration. The temporal durations of different intersections
are randomized across participants.
Proportion
• Damage to the hippocampus results in
profound episodic memory impairments and
disorientation in space and time1,2
• The hippocampus is crucial for creating
unique, non-overlapping memory
representations by the mechanism of
pattern separation3. We appear to use
spatiotemporal contextual information to
construct unique memory representations
for individual events
• Traditionally, hippocampal function has
been studied in the spatial domain.
However, recent research points to the
existence of ‘time cells’ which track
successively elapsed moments during an
empty temporal gap4
• Space and time are inextricably linked and
understanding the complex interplay of
memory for space and time may offer
insight into the principles of hippocampal
function
Task and Procedure
1
2
3
4
5
6
7
8
9
10
Number of intersections between compared pair
• Significantly greater accuracy
overall on distance
discrimination relative to
temporal discrimination
judgments
• No significant correlation
between distance and
temporal judgments
• Sign. greater proportion of
accurate temporal judgments
when both intersections were
“re-experienced” rather than
“known”
11
All sign. above chance at p < 0.05
Re-experience vs. Know
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Re-experience
Know
• Passive experience of navigation could
have contributed to low performance –
active navigation with slightly less
constrained timing might yield different
results
• A different pattern of results might be
observed in a familiar environment where
participants would not need to encode the
spatial features of the route
• Comparison of each individual duration
with a pre-learned duration
• Elapsed time during motion vs. pause
References
1. Moscovitch, M., Nadel, L., Winocur, G., Gilboa, A., &
Rosenbaum, R. (2006). The cognitive neuroscience
of remote episodic, semantic and spatial memory.
Current Opinion in Neurobiology, 16(2), 179-190.
2. Bellassen, V., Iglói, K., de Souza, L. C., Dubois, B., &
Rondi-Reig, L. (2012). Temporal order memory
assessed during spatiotemporal navigation as a
behavioral cognitive marker for differential
Alzheimer's disease diagnosis. The Journal of
Neuroscience, 32(6), 1942-1952.
3. Bakker, A., Kirwan, C., Miller, M., & Stark, C. (2008).
Pattern separation in the human hippocampal CA3
and dentate gyrus. Science, 319(5870), 1640-1642.
4. MacDonald, C., Lepage, K., Eden, U., &
Eichenbaum, H. (2011). Hippocampal “time cells”
bridge the gap in memory for discontiguous events.
Neuron, 71(4), 737-749.