Kant called Berkeley a "material idealist" on the grounds that Berkeley stated you are not and cannot experience objects outside a mind because the mind wouldn't understand what that means.
Kant seems more interested in how perceptions (thoughts, qualia, sensory perceptions, etc.) are filtered by a mind, and not so much by the cause of those perceptions.
At the end of the day, however, there is a large difference between the perceptions translated into neurons (as Berkeley seemed to suggest) and the perceived objects.
I would like to reference Magritte's painting The Treachery of Images. The neurons are much like the pipe, wait, no, the painting of a pipe. The painting is like a neuron representation of a pipe, but is not equivalent to a pipe, so in this Berkeley seemed dead on, and Kant seems to take the same for granted in his own critique of pure reason, for example, his own chair example where he says it is an immediate representation (note the term used) of a chair.
Do these two concepts not seem so linked? Are they not founded in much the same metaphysical ideal?