Abstract. Circuits composed of threshold gates (McCulloch-Pitts neurons, or perceptrons) are simplified models of neural circuits with the advantage that they are theoretically more tractable than their biological counterparts. However, when such threshold circuits are designed to perform a specific computational task they usually differ in one important respect from computations in the brain: they require very high activity. On average every second threshold gate fires (sets a "1" as output) during a computation. By contrast, the activity of neurons in the brain is much more sparse, with only about 1% of neurons firing. This mismatch between threshold and neuronal circuits is due to the particular complexity measures (circuit size and circuit depth) that have been minimized in previous threshold circuit constructions. In this article we investigate a new complexity measure for threshold circuits, energy complexity, whose minimization yields computations with sparse activity....
Wolfgang Maass, Kei Uchizawa, Rodney J. Douglas