Notes

Responses are a weighted average of the stimulus intensity, where the receptive field is the map of the weights.

The Linear Model At the bottom of the figure we can see a light stimulus, represented by a sine wave, followed by the response of the cell. The modelling idea is that we have a receptive field as shown in the top left of the figure (vertically oriented in this case) and the "product" of light stimulus and receptive field is passed through a trivial non-linearity, i.e., a threshold. We obtain a "rectified sinewave", where only the positive part "makes it through" the filter.

For a Linear Cell, Knowing the Receptive Field is Knowing Everything Through this linear model, you can predict the responses of neurons, which are dependent on where the light is shown on the receptive field.

Dependence of Responses on Orientation The same thing is true for orientation, you can multiply (convolve) the receptive field by stimuli of different orientations and the model will return the predicted neuronal response.