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IKCaInvolvement in the slow after-hyperpolarization in CA1
pyramidal cells and implications for spatial memory
Alexander B. KimSupervisor: Dr. Ray W. Turner
After-hyperpolarizations (AHPs)
Fast AHPVoltage-dependentCa2+-dependentLasts for 1-2 msBK channels
Medium AHPCa2+-dependentLasts for 50-100 msSK channels
Slow AHPOutward K+ currentCa2+-dependentLasts for secondsUnderlies spike accommodationUnknown channel(s)
IKCa is a candidate for the channel underlying the slow AHP in CA1 pyramidal cells
Spatial memory and the slow AHP
• Morris watermaze training reduces the slow AHP in CA1 pyramidal cells
• The slow AHP increases with age and correlates with spatial learning ability
• Application of a slow AHP blocker before retrieval impairs performance
Is modulation of IKCa responsible for the effects of learning on the slow AHP?
My Project
Hypothesis: The effects of learning on the slow AHP in CA1 pyramidal cells are mediated by modulation of IKCa.
Aim 1: Characterize the slow AHP in CA1 pyramidal cells of IKCa-/- mice
Aim 2: Evaluate spatial memory in IKCa-/- mice
Aim 3: Investigate the effects of spatial learning on the slow AHP in IKCa-/- mice
Generating a synaptically evoked slow AHP
IKCa-/- mice have a diminished slow AHP that is TRAM-34 insensitive
Water task training
Probe one day after training
Probe seven days after training
The effect of training on the slow AHP
Findings
• Deletion of IKCa diminishes the slow AHP in CA1 pyramidal cells.
• Deletion of IKCa alters spatial memory in the Morris water task.
Hypothesis: The effects of learning on the slow AHP in CA1 pyramidal cells are mediated by modulation of IKCa.
In progress…
AcknowledgementsBrian King
Bonita Gunning
Tom Seredynski
Simon Spanswick
Ray W. Turner
Cam Teskey
Ted Bartoletti
Hadhi Asmara
Colin Heath VI
Arsalan Rizwan
Steven Dykstra
Mirna Kruskic
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