Warning
This is A PREVIEW for NEST 3.0 and NOT an OFFICIAL RELEASE! Some functionality may not be available and information may be incomplete!
multimeter – Sampling continuous quantities from neurons¶
Description¶
Most sampling use cases are covered by the multimeter
, which
allows to record analog values from neurons. Models which have such
values expose a recordables
property that lists all recordable
quantities. This property can be inspected using GetDefaults
on
the model class or GetStatus
on a model instance. It cannot be
changed by the user.
>>> nest.GetDefaults('iaf_cond_alpha')['recordables']
['g_ex', 'g_in', 't_ref_remaining', 'V_m']
The record_from
property of a multimeter
(a list, empty by
default) can be set to contain the name(s) of one or more of these
recordables to have them sampled during simulation.
mm = nest.Create('multimeter', 1, {'record_from': ['V_m', 'g_ex']})
The sampling interval for recordings (given in ms) can be controlled
using the multimeter
parameter interval. The default value of
1.0 ms can be changed by supplying a new value either in the call to
Create
or by using SetStatus
on the model instance.
nest.SetStatus(mm, 'interval': 0.1})
The recording interval must be greater than or equal to the simulation resolution, which defaults to 0.1 ms.
Warning
The set of variables to record from and the recording interval must
be set before the multimeter
is connected to any neuron.
These properties cannot be changed afterwards.
After configuration, a multimeter
can be connected to the neurons
it should record from by using the standard Connect
routine.
neurons = nest.Create('iaf_psc_alpha', 100)
nest.Connect(mm, neurons)
To learn more about possible connection patterns and additional
options when using Connect
, see the guide on connection
management.
The above call to Connect
would fail if the neurons would not
support the sampling of the values V_m and g_ex. It would also
fail if carried out in the wrong direction, i.e., trying to connect the
neurons to mm.
Note
A pre-configured multimeter
is available under the name voltmeter
. Its
record_from
property is already set to record the variable V_m
from the neurons it is connected to.