Beyond Vanilla LTP Spike-timing-dependent-plasticity or STDP - - PowerPoint PPT Presentation

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beyond vanilla ltp spike timing dependent plasticity or
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Beyond Vanilla LTP Spike-timing-dependent-plasticity or STDP - - PowerPoint PPT Presentation

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Beyond Vanilla LTP Spike-timing-dependent-plasticity or STDP Hebbian learning rule aSN W MN,aSN MN learning threshold under which LTD can occur w ij = x j (v i - ) Stimulation electrode Recording electrode (extracellular) R di l

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SLIDE 1

Beyond Vanilla LTP Spike-timing-dependent-plasticity

  • r

STDP

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SLIDE 2

Hebbian learning rule aSN MN WMN,aSN

Δwij = μ xj (vi - φ)

learning threshold under which LTD can occur

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SLIDE 3

Stimulation electrode R di l d ( ll l ) Recording electrode (extracellular) Recording electrode (intracellular)

100%

Baseline

5 sec

100 Hz tetanus

... 2 hours

Tetanus

tetanus

postsynaptic activation > threshold to increase wij

Δwij = μ xj (vi - φ)

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SLIDE 4

Recording electrode (extracellular) Recording electrode (intracellular)

5 sec

... 2 hours

100%

Baseline 20 Hz

20 Hz

postsynaptic activation < threshold to decrease wij

Δwij = μ xj (vi - φ)

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vi vi xj time

Δwij = μ * xj * (vi-φ)

time 100 Hz vi xj time i time 20 Hz vi xj time time 10 Hz 10 Hz

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Induction of LTP or LTD depends not only on firing frequency but Induction of LTP or LTD depends not only on firing frequency but also on precise temporal relationship between the pre- and postsynaptic action potentials.

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SLIDE 7

Paired

Pre Post

Paired Pre or post only tpost - tpre = 5ms

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SLIDE 8

Paired

Pre Post

Paired Pre or post only tpost - tpre = 5ms

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SLIDE 9

Paired

Pre Post

Paired Pre or post only Baseline tpost - tpre = 5ms Repeated pairing (20x)

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SLIDE 10

Pre Post Paired pre-only post-only

Experimental manipulation

pre and post AP's separated by 5 ms pre post 10x

< 20 Hz: no LTP > 20 Hz: more LTP

pre 20 Hz 20 Hz 4 seconds

Markram et al Regulation of synaptic efficacy by coincidence of postsynaptic APs and EPSPs Markram et al. Regulation of synaptic efficacy by coincidence of postsynaptic APs and EPSPs.

  • Science. 1997 Jan 10;275(5297):213
  • 5.
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SLIDE 11
  • 1. Stimulate cell1:

> burst of action potentials in cell1

(1) Lets assume a burst of action potentials is first evoked in cell 1. This burst of action cell 1 cell 2

  • > burst of action potentials in cell1
  • > EPSPs in cell2

potentials will evoke an EPSP in cell 2. (2)Subsequently a burst of action potentials is evoked in cell 2, which will evoke and EPSP in cell 1. (1) (2) In the example shown here, (1) and (2) are separated by 100 ms. Because the cells are reciprocally connected, in each cell, the burst of action potentials and evoked EPSPs are separated by 100ms. In cell 1, the burst of action potentials precceeds the EPSP by (1) (2)

Bursts of AP triggered 10 ms

p p y 100 ms and in cell 2, the EPSP preceeds the action potentials by 100 ms. (2)

apart

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SLIDE 12
  • 1. Stimulate cell1:

> burst of action potentials in cell1

(1) Lets assume a burst of action potentials is first evoked in cell 1. This burst of action cell 1 cell 2

  • > burst of action potentials in cell1
  • > EPSPs in cell2

potentials will evoke an EPSP in cell 2. (2)Subsequently a burst of action potentials is evoked in cell 2, which will evoke and EPSP in cell 1. (1) (2)

  • 2. Stimulate cell2:
  • > burst of action potentials in cell2
  • > EPSPs in cell1

In the example shown here, (1) and (2) are separated by 100 ms. Because the cells are reciprocally connected, in each cell, the burst of action potentials and evoked EPSPs are separated by 100ms. In cell 1, the burst of action potentials precceeds the EPSP by (1) (2)

Bursts of AP triggered 10 ms

p p y 100 ms and in cell 2, the EPSP preceeds the action potentials by 100 ms. (2)

apart

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SLIDE 13
  • 1. Stimulate cell1:

> burst of action potentials in cell1

(1) Lets assume a burst of action potentials is first evoked in cell 1. This burst of action cell 1 cell 2

  • > burst of action potentials in cell1
  • > EPSPs in cell2

potentials will evoke an EPSP in cell 2. (2)Subsequently a burst of action potentials is evoked in cell 2, which will evoke and EPSP in cell 1. (1) (2)

  • 2. Stimulate cell2:
  • > burst of action potentials in cell2
  • > EPSPs in cell1

In the example shown here, (1) and (2) are separated by 100 ms. Because the cells are reciprocally connected, in each cell, the burst of action potentials and evoked EPSPs are separated by 100ms. In cell 1, the burst of action potentials precceeds the EPSP by (1) (2)

Cell1: APs 100ms before EPSPs

Bursts of AP triggered 10 ms

p p y 100 ms and in cell 2, the EPSP preceeds the action potentials by 100 ms. (2)

Cell2: EPSPs 100ms before APs

apart

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SLIDE 14
  • 1. Stimulate cell1:

> burst of action potentials in cell1

(1) Lets assume a burst of action potentials is first evoked in cell 1. This burst of action cell 1 cell 2

  • > burst of action potentials in cell1
  • > EPSPs in cell2

potentials will evoke an EPSP in cell 2. (2)Subsequently a burst of action potentials is evoked in cell 2, which will evoke and EPSP in cell 1. (1) (2)

  • 2. Stimulate cell2:
  • > burst of action potentials in cell2
  • > EPSPs in cell1

In the example shown here, (1) and (2) are separated by 100 ms. Because the cells are reciprocally connected, in each cell, the burst of action potentials and evoked EPSPs are separated by 100ms. In cell 1, the burst of action potentials precceeds the EPSP by (1) (2)

Cell1: APs 100ms before EPSPs

Bursts of AP triggered 10 ms

p p y 100 ms and in cell 2, the EPSP preceeds the action potentials by 100 ms. (2)

Cell2: EPSPs 100ms before APs

EPSP : input from presynaptic cell

apart

EPSP : input from presynaptic cell AP: output from postsynaptic cell EPSP followed by AP: pre before post: tpre - tpost < 0 y p p

pre post

AP followed by EPSP: post before pre: tpre - tpost > 0

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SLIDE 15

cell 1 cell 2 Strengtheningof synaptic strength was obtained h th t t ll fi d 10 ft it EPSP

AP before EPSP: weakening

when the postsynaptc cell fired 10 ms after its EPSP Weakeningof synaptic strength was obtained when the postsynaptic cell fired 10 ms before its EPSP No change in synaptic strength was obtained when the

  • f synaptic strength

EPSP before AP: strengthening

Bursts of AP triggered 100 ms apart Bursts of AP triggered 10 ms

No change in synaptic strength was obtained when the postsynaptic EPSP and AP were separated by 100ms in either direction.

EPSP before AP: strengthening

  • f synaptic strength

Bursts of AP triggered 100 ms apart Bursts of AP triggered 10 ms apart

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SLIDE 16

Summary: Summary: 1) If a pre-synaptic cell fires BEFORE a connected postsynaptic cell, the synapse connecting them increases in strength 2) If pre-synaptic cell fires AFTER a connected postsynaptic cell, the synpase between them decreases in strength

t t pre post pre pre post pre p post p post

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SLIDE 17

Consider our previous example on classical conditioning: p p g Sensory input Motor output Food F S M

pre before post

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The change in EPSC (exitatory postsynaptic The change in EPSC (exitatory postsynaptic current) is plotted as a function of the time elapsed between the postsynaptic action potential and the the postsynaptic EPSP during simultaneous stimulation of pre- and postsynaptic ll cells. Bi, GQ and Poo, MM. Synaptic modifications in cultured hippocampal neurons: dependence on spike timing, synaptic strength, and postsynaptic cell type. J Neurosci. 1998 Dec 15;18(24):10464-72.

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SLIDE 19

b f t pre before post post before pre

Δt = timepre - timepost

Bi, GQ and Poo, MM. Synaptic modifications in cultured hippocampal neurons: dependence on spike timing synaptic Song Miller and Abbott Competitive Hebbian hippocampal neurons: dependence on spike timing, synaptic strength, and postsynaptic cell type. J Neurosci. 1998 Dec 15;18(24):10464-72. Song, Miller and Abbott, Competitive Hebbian learning through spike

  • timing-dependent synaptic

plasticity. Nat Neurosci. 2000 Sep;3(9):919

  • 26.
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SLIDE 20
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SLIDE 21

Δw pre post 5 ms 20 ms

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. . N 1 . N presynaptic spike trains N synaptic weight

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. . N 1 . N presynaptic spike trains N synaptic weight

leaky integrate and fire current due to excitatory inputs current due to excitatory inputs

[τ dv/dt = -v + inputs]

excitatory inputs excitatory inputs

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SLIDE 24

When Vm >= -54 mV

. . N 1

When Vm >= -54 mV, neuron fires and Vm = -70 mV

. N presynaptic spike trains N synaptic weight

leaky integrate and fire current due to excitatory inputs current due to excitatory inputs excitatory inputs excitatory inputs

Vrest = -70 mV, Eex = 0 mV; Ein = -70 mV

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SLIDE 25

postsynaptic spikes trains napses

. . N

naptic spike syn

. N presynaptic spike trains

presyn time weights

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SLIDE 26

postsynaptic spikes

pre before post b f

trains napses

. . N Δt = timepre - timepost

post before pre

naptic spike syn

. N presynaptic spike trains

presyn time weights

NO LEARNING: A+ = 0 and A- = 0

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SLIDE 27

A+ >0 and A- = 0 A+ =0 and A- > 0

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SLIDE 28

A+ ~= A- A+ < A-

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SLIDE 29
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SLIDE 30
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SLIDE 31

Stabilizes Hebbian learning Introduces competition Favors synchronous presynaptic events Δt = time

  • time

t

Δt time

pre timepost

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SLIDE 32

Issues: At high firing rates, when pre and postsynaptic neurons are phase-locked both parts of the learning rule are phase locked, both parts of the learning rule apply for any given spike!

20 ms (50 Hz) pre 30 ms post 10 ms

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SLIDE 33

Issues: At high firing rates, when pre and postsynaptic neurons are phase-locked, both parts of the learning rule apply for any given spike! pp y y g p

20 ms (50 Hz) pre post + + + +

  • postsynaptic spikes interacts with each

postsynaptic spikes interacts with each presynaptic spike and effects sum up linearly!

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SLIDE 34

Issues: At high firing rates, when pre and postsynaptic neurons are phase-locked, both parts of the learning rule apply for any given spike! pp y y g p

20 ms (50 Hz) pre post +

  • postsynaptic spikes interacts only with

postsynaptic spikes interacts only with immediatly preceeding presynaptic spikes

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SLIDE 35

Here we have systematically varied the rate, timing and number of coincident afferents in order to explore the rules that govern induction of long-term plasticity b t ti ll t d thi k t ft d L5 i t i l t between monosynaptically connected thick, tufted L5 neurons in rat visual cortex. Our experiments reveal a joint dependence of plasticity on timing and rate, as well as a novel form of cooperativity operating even when the postsynaptic AP is evoked by current injection Based on these experiments we have constructed a evoked by current injection. Based on these experiments we have constructed a quantitative description, which accurately predicts the build-up of potentiation and depression during random firing. Sjostrom PJ, Turrigiano GG, and Nelson SB. Rate, timing, and cooperativity jointly determine cortical synaptic plasticity. Neuron 32: 1149-1164, 2001.

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presynaptic t ti postsynaptic measure for strength of synapse

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SLIDE 37

1) LTP depends on stimulation frequency

40 Hz 0.1 Hz

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1) LTP depends on stimulation frequency

40 Hz 0.1 Hz

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SLIDE 39

1) LTP depends on stimulation frequency

40 Hz 0.1 Hz

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At high frequencies, LTP always dominates!

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At high frequencies, LTP always dominates!

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All spike interactions li l Only nearest spike All spike interactions sum linearly, but if LTP sum linearly spike interactions count y, is present, LTD is not applied

All three models used frequency and voltage dependencies determined from data in this paper.

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Models tested with new data NOT used for fitting!