Memory failures, dream illusions and mental malfunction.

Abstract

Dreams are widely believed to be produced as the brain's memory circuits are reinforced during sleep by self-generated brain waves. Reinforcement maintains synaptic strengths in the 'dedicated' ranges that support circuit functions. Without these activations, turnover of molecules essential for synaptic function would lead to deleterious alterations in, and eventual loss of, memories. The pathological processes underlying many mental disorders appear to exert their deleterious influences by inducing abnormalities in brain waves, largely in slow waves of less than about 14 cycles/s. The pathologically altered slow waves, in turn, cause long-lasting weakening or dysfunction of synapses of affected circuits, frequently resulting in mental disorders and deviant sleep. These abnormalities can be remediated for varying periods by therapies that restore normal brain waves. With many trillions of synapses between billions of neurons in enormously complex circuits needing reinforcement during sleep, the process is susceptible to failures. As a result, some synapses 'normally' weaken or become dysfunctional, accumulating to the greatest extent in old memory circuits. Activation of resulting incompetent circuits during waking may lead to hallucinations and delusions; activation during sleep may lead to dreams with bizarre, incoherent or impossible contents.