dc_generator – Provide a direct current (DC) input

Description

The dc_generator provides a constant DC input to the connected node. The unit of the current is pA.

The dc_generator is rather inefficient, since it needs to send the same current information on each time step. If you only need a constant bias current into a neuron, you could instead directly set the property I_e, which is available in many neuron models.

All stimulation devices share the parameters start and stop, which control the stimulation period. The property origin is a global offset that shifts the stimulation period. All three values are set as times in ms.

• For spike-emitting devices, only spikes with times t that fulfill \(\mathrm{start} < t \leq \mathrm{stop}\) are emitted. Spikes that have timestamp of \(t = \mathrm{start}\) are not emitted.

• For current-emitting devices, the current is activated and deactivated such that the current first affects the target dynamics during the update step \((\mathrm{start}, \mathrm{start}+h]\), that is, an effect can be recorded at the earliest at time \(\mathrm{start}+h\). The last interval during which the current affects the target’s dynamics is \((\textrm{stop}-h, \textrm{stop}]\).

The property stimulus_source defaults to an empty string. It can be set to the name of a stimulation backend, in which case it will take its parameters from the configured backend instead of from the internally stored values. More details on available backends and their properties can be found in the guide to stimulating the network.

Parameters

label

A string specifying an arbitrary textual label for the device. Stimulation backends might use the label to generate device specific identifiers like filenames and such. Default: "".

origin

A positive floating point number used as the reference time in ms for start and stop. Default: 0.0.

start

A positive floating point number specifying the activation time in ms, relative to origin. Default: 0.0.

stimulus_source

A string specifying the name of the stimulation backend from which to get the data for updating the stimulus parameters of the device. By default, the device uses its internally stored parameters for updating the stimulus. Default: "".

stop

A floating point number specifying the deactivation time in ms, relative to origin. The value of stop must be greater than or equal to start. Default: infinity.

amplitude

Amplitude of current (pA)

Set parameters from a stimulation backend

The parameters in this stimulation device can be updated with input coming from a stimulation backend. The data structure used for the update holds one value for each of the parameters mentioned above. The indexing is as follows:

0. amplitude

Sends

CurrentEvent

See also

ac_generator, noise_generator, step_current_generator

Examples using this model

• Classes to encapsulate the neuronal networks.

• Comparing precise and grid-based neuron models

• Constructing and simulating compartmental models with different receptor types

• Intrinsic currents subthreshold

• Multi-compartment neuron example

• PyNEST Microcircuit: Network Class

• Sensitivity to perturbation

• Short-term depression example

• Short-term facilitation example

• Testing the adapting exponential integrate and fire model in NEST (Brette and Gerstner Fig 2C)

• Testing the adapting exponential integrate and fire model in NEST (Brette and Gerstner Fig 3D)