working reference memory following fimbra fornix lesions
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Working & Reference Memory Following Fimbra-Fornix Lesions

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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.

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Presentation Transcript
purpose
Purpose
  • To determine the role of the septo-hippocampal system in working and reference memory
predictions
Predictions
  • Lesions of the fimbria-fornix will produce deficits in spatial working and reference memories
subjects
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
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
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 memory1
Working Memory

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working memory2
Working Memory

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Normal

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working memory3
Working Memory

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F-F Lesioned

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reference memory
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 memory1
Reference Memory

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reference memory2
Reference Memory

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Normal

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reference memory3
Reference Memory

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F-F Lesioned

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Cue 2

measures
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
slide18
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
conclusions
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
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
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)
references1
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
Remember
  • Think conceptually when reading the literature, don’t just describe methods of study.
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