[ENH] Add Grinten / Stevenick / Lozano model (Dynaphos)

[tallyhawley]

Description

Adds the Dynaphos model outlined in Grinten, Steveninck, Lozano (2022).

This is a model which cannot separate its temporal and spatial components. It extends BaseModel.

This is because each phosphene's brightness is not determined by instantaneous current, but by the effective current, which is affected by the memory trace (which builds up over time). This means that in order to determine the brightness at a given time step, we need to have calculated all prior time steps-- and time steps with identical instantaneous stimulus do not necessarily have identical percepts.

All model constants can be set in its constructor, but the default values are those specified in the paper.

It has a default frame rate of 50fps (dt = 20ms), but this can be set. If t_percept is not passed to predict_percept, a percept will be returned at a frame rate determined by dt.

The amplitude for each electrode at each time-step is determined by the maximum amplitude of the stimulus on that electrode over the duration of time step.

It takes any stimulus (with a time component), and assumes a default frequency & pulse duration of 300Hz and 0.17ms respectively. However, if the stimulus is a BiphasicPulseTrain, it will use the frequency and pulse duration specified in the stimulus metadata.

Activation and brightness trends are very similar to those seen in the referenced paper:

Pulse2percept implementation of the Dynaphos model

Original implementation of the Dynaphos model

Timing information (time to run predict_percept on a 1sec stimulus).
Model is built with default parameters.
Grid side length was set using xystep, and FPS was set using dt.

Closes #526

Type of Change

• New feature (non-breaking change which adds functionality)

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[jgranley]

Looks great! Looks likes its really fast too, was not expecting that with the raw python, but must be a good implementation

[codecov-commenter]

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