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Functional dissection of the CA3-CA1 learning rule. Sam Wang Princeton University http://synapse.princeton.edu/~sam/Wang-STDP.ppt. Laboratory of Sam Wang. Brain scaling and evolution: Mark Burish Damon Clark Kim Hatch Harrison Hao Yuan Kueh Jennifer Shultz Matt Wagers Krysta Wyatt. - PowerPoint PPT Presentation
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Functional dissection of the CA3-CA1 learning ruleFunctional dissection of the CA3-CA1 learning rule
Sam WangPrinceton University
http://synapse.princeton.edu/~sam/Wang-STDP.ppt
Optical physiology andOptical physiology and synaptic plasticity:synaptic plasticity:
Shari GelberShari GelberDaniel O’ConnorDaniel O’ConnorDmitry SarkisovDmitry SarkisovShy ShohamShy ShohamMegan SullivanMegan SullivanGayle WittenbergGayle Wittenberg
Brain scaling andBrain scaling and evolution:evolution:
Mark BurishMark BurishDamon ClarkDamon ClarkKim Hatch HarrisonKim Hatch HarrisonHao Yuan KuehHao Yuan KuehJennifer ShultzJennifer ShultzMatt WagersMatt WagersKrysta WyattKrysta Wyatt
Laboratory of Sam WangLaboratory of Sam Wang
Too many learning rules!
Abbott and Nelson,Nat. Neurosci.
CA3-CA1 synapse of hippocampus
Rich history of extracellular and single-cell recordingThe cell biology and plasticity literature is vastOne synapse per connectionHas AMPA, NMDA, mGluR,…
Plasticity at CA3-CA1: a separable process?
• Is timing between single spikes sufficient to describe the actual learning rule?
• How different are the requirements for potentiation and depression? Are these full inverses of each other?
• How might the learning rule map to behavior?• Can cell biology help clarify these issues
conceptually?
Questions at the CA3-CA1 synapse
Nishiyama et al. 2000 Nature 408:58480 pairings at 5 Hz Cesium pipet solution
Pike et al. 1999Journal of Physiology 518:57140 pairings at 5 Hz Four epochs (10 pairings each) at 10-s intervals
Christie et al. 1996Learning and Memory 3:160900 pairings at 3 HzEpochs (30-60 pairings each) at 5-s intervals
At the CA3-CA1 synapse, pairing single APs gives…
…LTP.
…no change.
…LTD.
At CA3-CA1 synapses, pairing of single spikes fails to induce potentiation
Single pre+post APs
100 pairings with t=0-7 ms (pre before post)
Pairing frequency 0.1-5 Hz
However…
In Nishiyama et al. Cesium replaced Potassiumin the intracellular pipette solution
This will…-depolarize neuron -block A-type K channels in dendrite-broaden action potentials
Potassium Cesium
Cs+
K+
pairings given at 5 Hz
Cs+
K+
…can bursts of APs emulate Cs+?
LTP induction requires postsynaptic bursting
CA1 neurons fire bursts during theta oscillation
Pairings must be given at high frequency
t
Observations on the LTP learning rule
• Potentiation requires postsynaptic bursts
• Pairings are effective at 5 Hz (near theta)
…does depression have these requirements?
LTD occurs under many timing conditions
All pairings given at 5 Hz
Requirement Theta BurstingLTP yes yesLTD no no
Conclusions so far
• Potentiation and depression have different general induction requirements.– Potentiation: active exploration (causal, bursts, 5 Hz)– Depression: many conditions
• During theta, the rule acts like a phase detector.• At other times, the rule is depression-only.
Why not explore parameter space exhaustively?
…because it’s exhausting!
Shy Shoham
Uncaging in spatial patterns: High-throughput screening of neural responses
Resolution: <1 micron30,000 locations per second
Subthreshold and spiking behavior for “natural” stimulation ensembles
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Now play movie athttp://synapse.princeton.edu/~sam/shoham-oconnor-movie.avi
Local amplification in dendritic branches
Strategies for separating LTD and LTP
LTD and LTP are separable
LTD is fully reversible
LTP is not fully reversible!
After being induced, LTP becomes locked in
The starting distribution of CA3-CA1 synapses
>1 Hz
>10 Hz >10 Hz
The CA3-CA1 learning rule
…butdissectable?
Complex…
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