ABSTRACT
The largely consistent columnar circuitry observed throughout the cortex may serve to continuously predict bottom-up activation based on invariant memories. This “memory-prediction” function is essential to efficient and accurate perception. Many of the defined cognitive deficits associated with schizophrenia suggest a breakdown of memory-prediction function. As deficits in memory-prediction function are proposed to lie more proximal to the biological causes of schizophrenia than deficits in standard cognitive constructs, tests that more directly probe memory-prediction function may be especially sensitive predictors of conversion in individuals at high-risk for schizophrenia. In this article, we review the conceptual basis for this hypothesis, and outline how it may be tested with specific cognitive paradigms. The accurate identification of cognitive processes that precede the onset of psychosis will not only be useful for clinicians to predict which young people are at greatest risk for schizophrenia, but will also help determine the neurobiology of psychosis onset, thus leading to new and effective treatments for preventing schizophrenia and other psychoses.
Despite the common experience of the world as mostly stable and meaningful, the human nervous system continuously engages with a vast array of ambiguous and constantly changing sensory signals. To organise coherent percepts from the fragmented and unstable sensory signals that constitute experience, and to allow for coordinated interaction with the world that these signals represent, the human nervous system must fill in the gaps of sensation, generalise across observations, prioritise stimuli for in-depth processing, and make immediate judgments regarding the meaning of sensory input. The memory-prediction model of cortical function posits that a uniform columnar circuitry throughout the cortex underpins a common algorithm that emphasizes the consistent aspects of experience in memory storage and uses these learned consistencies to make ongoing predictions about bottom-up stimulation across the cortical hierarchy, thus stabilising perception. A recent review suggests that impairments in memory-prediction function may constitute the primary cognitive deficit associated with schizophrenia and may underlie the development of hallucinations and delusions.1 Here we will briefly review the memory-prediction model and argue that anatomical abnormalities and cognitive deficits associated with schizophrenia suggest widespread and early disruption of the circuitry underlying memory-prediction function. We will also propose that a series of neurocognitive tests described herein which measure these processes may exhibit strong predictive power for later onset of psychosis.
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