Working & Reference Memory Following Fimbra-Fornix Lesions.
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Transcript of Working & Reference Memory Following Fimbra-Fornix Lesions.
Working & Reference Memory Following Fimbra-Fornix Lesions
Purpose
To determine the role of the septo-hippocampal system in working and reference memory
Predictions
Lesions of the fimbria-fornix will produce deficits in spatial working and reference memories
Subjects
6 female Long-Evans rats, housed at NIU Approximately 6 months in age 3 subjects receive F-F lesions 3 unoperated control
Fimbria-fornix lesion
Rats will be anesthetized with a mixture of isofluorane and oxygen during the surgery.
Lesions will be made using standard stereotaxic techniques with the aid of a surgical microscope.
Prior to making the incision, the hair will be shaved and the surrounding area will be scrubbed with Betadine.
There will be two lesion sites per hemisphere, using coordinates with respect to bregma and the surface of the dura: -1.3mm posterior, 1.5mm lateral, and –3.6 mm ventral; -1.5mm posterior, 0.5mm lateral, and 3.3 mm ventral.
Fimbria-fornix lesions will be produced by passing 1.5mAmp current for 40 seconds.
Following lesion incision will be sutured General appearance and weight will be monitored every day for
the duration of behavioral testing
Working Memory
Prior to training with baited arms, rats will be given two habituation sessions (15 min) in which the rats will be free to explore the radial eight-arm maze
Rats will receive five training sessions in which each arm of the radial eight-arm maze will be baited with one half of a fruit loop
placed into the center of the maze and the arms visited will be recorded
After all of the arms have been visited or 15 minutes has elapsed the rats will be removed from the apparatus
maze will be cleaned with Windex prior to running the next rat
Working Memory
Cue 1
Cue 3
Cue 2
Working Memory
Cue 1
Cue 3
Cue 2
Normal
Working Memory
Cue 1
Cue 3
Cue 2
F-F Lesioned
Reference Memory
Subsequent to completion of working memory training sessions
Rats will receive five training sessions in which only four of the eight arms will be baited
After all of the arms with bait have been visited or 15 minutes has elapsed, the rats will be removed from the apparatus
Reference Memory
Cue 1
Cue 2
Cue 3
Reference Memory
Cue 1
Cue 2
Cue 3
Normal
Reference Memory
Cue 1
Cue 2
Cue 3
F-F Lesioned
Measures
Several measures will be used to characterize the rat’s performance: number of repeat visits to an arm (errors) time to visit all arms
Number of Errors
0
5
10
15
20
D1 D2 D3 D4 D5
Av
era
ge
Nu
mb
er
of
Err
ors
F-F
C
Main effect of day F(4,16)=30, p<.05 Main effect of group F(1,4)=697.69, p<.05 Significant dayXgroup interaction F(4,16)=18, p<.05
Sum of Squares df Mean Square F p
day 72 4 18 30 0
day * group 43.2 4 10.8 18 0
Error(day) 9.6 16 0.6
group 1116.3 1 1116.3 697.6875 0
Error(group) 6.4 4 1.6
Time to Visit All Arms
0
2
4
6
8
10
12
14
16
D1 D2 D3 D4 D5
Tim
e (
Min
)
F-F
C
Conclusions
F-F lesions distrupt working and reference memory
Discuss literature that supports this and contradicts this Packard M Hirsh R White N (1989) Differential effects of fornix and caudate
nucleus lesions on two radial maze tasks: evidence for multiple memory systems.
Future work (recovery, model for memory impairments, Alzheimer's disease)
Things to consider
How are the rats solving these two tasks? Is reference memory the same as place
learning? What do these studies imply in terms of the
role of the hippocampus in memory?
References
Chapter 11 Working memory & Reference memory (pg. 319-
20) Spatial memory in Radial Maze (pg. 326-29) Memory mechanisms (pg.332-43)
Chapter 12 Memory in food storing birds (pg. 354-58)
References
pubmed.org psycinfo Terms
Working memory & reference memory Hippocampus & fimbria-fornix Place learning Spatial memory Morris water maze
Important People David Olton Larry Squire Eric Kandel Ian Whishaw
Remember
Think conceptually when reading the literature, don’t just describe methods of study.