As will be discussed below, an imbalance of excitation and inhibition could be due to increased glutamatergic (excita- tory) signaling, or to a reduction in inhibition due to a reduc- tion in GABAergic signaling. Hussman (2001) has earlier suggested that suppressed GABAergic inhibition is a com- mon feature of the autistic brain. Such a problem could also be exacerbated by abnormal modulatory control of the learn- ing and memory processes that enable and regulate the normal progressive differentiation and elaboration of informa- tion processing in the developing brain, because progressive functional differentiation increases processing reliability and representational salience, and thereby reduces process noise