Understanding the role of dysfunctional hippocampal-parahippocampal representations of space in schizophrenia

The etiology of schizophrenia is yet to be fully understood, thus limiting the scope of interventions for symptom reduction. Among features less frequently researched and addressed are deficits in spatial cognition, which may contribute to cognitive disorganization, a core symptom of schizophrenia. The purpose of this review is to summarize the known deficits in spatial memory and neural circuits associated with this neuropsychiatric disorder, synthesize key findings, and make recommendations regarding further areas of research needed in the literature. Our review identified several key areas in the brain’s spatial navigation system. First, abnormal hippocampal neuronal responsivity is well-documented in patients with schizophrenia and is associated with impairments in the use of map-based strategies during navigation. Second, alterations in the synchronized firing of neurons in theta frequencies as well as the coupling of theta oscillations across cortical circuits are shown to associate with spatial problem solving. Third, recent research reports that neural representations of space, specifically relating to grid cell function, are abnormal in patients with schizophrenia and are related to deficits in navigation. We suggest that an understanding of the neural bases of behavioral and cognitive symptomology, such as cognitive disorganization, in schizophrenia will benefit from future work advancing integrated theoretical frameworks that include mechanisms of altered hippocampal-parahippocampal neuronal responses including grid cell dysfunction and altered neural oscillation patterns involved in spatial cognition.