Eye movement dysfunction in schizophrenia: A heritable characteristic for enhancing phenotype definition

Abstract

The occurrence of ocular motor dysfunction in schizophrenia patients and their first-degree biological relatives is remarkably consistent, suggesting that abnormal smooth pursuit and saccadic oculomotion are heritable characteristics that can be used to identify gene carriers for schizophrenia. Saccadic system dysfunction probably reflects a generalized deficit in prefrontal cortical functioning, rather than a specific deficit in saccade system functioning. Although abnormal smooth pursuit has also been associated with impaired frontal functioning, it is unclear whether these two types of dysfunction arise from the same neural pathology. Therefore, deviant smooth pursuit and saccadic oculomotion may constitute unrelated factors identifying two different types of genetic risk. Alternatively, they may derive from a single risk factor that causes (a) both types of deficits to be expressed together or (b) each type to be expressed separately as pleiotropic manifestations of the underlying genotype. Although a full complement of pursuit and saccade measures has not been examined together in family studies of schizophrenia, there is obvious value in determining how these measures relate to one another in schizophrenia families and whether they can be used in combination to enhance phenotype definition to facilitate the search for schizophrenia susceptibility genes.

Temporal Information Processing in Short- and Long-Term Memory of Patients with Schizophrenia

“…Hence, temporal information helps patients to overcome inappropriate semantic clustering. This is in line with the desinhibition deficit in schizophrenia and the assumption that task-irrelevant information impedes patients' performances, see, e.g., [84]. Patients have difficulties suppressing an imminent stimulus-driven response (according to semantic content) in favor of a voluntary action (by integrating temporal information).…”

Individual differences in visual science: What can be learned and what is good experimental practice?

“…For example, it has been suggested that smooth pursuit is an endophenotype for schizophrenia (Calkins & Iacono, 2000; Allen, Griss, Folley, Hawkins, & Pearlson, 2009). Investigating the neurological and genetic basis of individual differences in a candidate endophenotype may provide insights into the biological basis of a clinical condition more easily than attempting to correlate the condition itself with biological variation.…”

Basal Ganglia Shape Abnormalities in the Unaffected Siblings of Schizophrenia Patients

“…Basal ganglia dysfunction, assessed with functional MRI, has been reported in schizophrenia and their unaffected siblings (13-15). Also, the caudate is involved in smooth pursuit and saccadic eye movement (16,17), which have been shown to be abnormal in individuals with schizophrenia and their relatives (18,19).…”

“…Basal ganglia dysfunction, assessed with functional MRI, has been reported in schizophrenia and their unaffected siblings (13-15). Also, the caudate is involved in smooth pursuit and saccadic eye movement (16,17), which have been shown to be abnormal in individuals with schizophrenia and their relatives (18,19).Enlargement of basal ganglia volume in schizophrenia has been reported (20-22); however, these findings have been generally attributed to treatment with older generation ("typical") antipsychotic medications that act primarily as antagonists at D2-type dopamine receptors in the basal ganglia (23,24). Volumetric abnormalities in various brain areas have been reported in the non-psychotic first-degree relatives of schizophrenia patients (25-27), but there have been relatively few studies of basal ganglia structure in this population.…”