1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
|
.. currentmodule:: brian
.. index::
pair: example usage; NeuronGroup
pair: example usage; run
pair: example usage; show
pair: example usage; network_operation
pair: example usage; Clock
pair: example usage; plot
pair: example usage; StateMonitor
.. _example-misc_multipleclocks:
Example: multipleclocks (misc)
==============================
This example demonstrates using different clocks for different objects
in the network. The clock ``simclock`` is the clock used for the
underlying simulation. The clock ``monclock`` is the clock used for
monitoring the membrane potential. This monitoring takes place less
frequently than the simulation update step to save time and memory.
Finally, the clock ``inputclock`` controls when the external 'current'
``Iext`` should be updated. In this case, we update it infrequently
so we can see the effect on the network.
This example also demonstrates the @network_operation decorator. A
function with this decorator will be run as part of the network
update step, in sync with the clock provided (or the default one
if none is provided).
::
from brian import *
# define the three clocks
simclock = Clock(dt=0.1 * ms)
monclock = Clock(dt=0.3 * ms)
inputclock = Clock(dt=100 * ms)
# simple leaky I&F model with external 'current' Iext as a parameter
tau = 10 * ms
eqs = '''
dV/dt = (-V+Iext)/tau : volt
Iext: volt
'''
# A single leaky I&F neuron with simclock as its clock
G = NeuronGroup(1, model=eqs, reset=0 * mV, threshold=10 * mV, clock=simclock)
G.V = 5 * mV
# This function will be run in sync with inputclock i.e. every 100 ms
@network_operation(clock=inputclock)
def update_Iext():
G.Iext = rand(len(G)) * 20 * mV
# V is monitored in sync with monclock
MV = StateMonitor(G, 'V', record=0, clock=monclock)
# run and plot
run(1000 * ms)
plot(MV.times / ms, MV[0] / mV)
show()
# You should see 10 different regions, sometimes Iext will be above threshold
# in which case you will see regular spiking at different rates, and sometimes
# it will be below threshold in which case you'll see exponential decay to that
# value
|
