Studies of the parvocellular and magnocellular visual channels in health and psychopathology

Susceptibility to the Müller-Lyer illusion was studied in healthy subjects and patients with schizophrenia. The experiments used images subjected to wavelet filtration and containing spectra consisting of high or low spatial frequencies. Patients at the initial state of the clinical manifestations of schizophrenia were more susceptible to the Müller-Lyer illusion than normal observers on presentation of images with spectra consisting of high spatial frequencies, to which neurons in the parvocellular pathway are more sensitive. At the same time, there was no difference in the susceptibility to the Müller-Lyer illusion on presentation of images with spectra consisting of low spatial frequencies, to which neurons in the magnocellular pathway are more sensitive. Patients with long-term schizophrenia were more susceptible to illusions on presentation of all Müller-Lyer illusion images. These data are interpreted as evidence for impairments to the functioning of the parvocellular visual channels at the stage of the early clinical manifestations of schizophrenia, with preservation of the functioning of the magnocellular channel. Patients with long-term schizophrenia were characterized by impairments to both the parvocellular and magnocellular visual channels. © 2014 Springer Science+Business Media New York.