Schizophrenia patients fail to see faces as a whole
MedWire News: The difficulty schizophrenia patients have in recognizing and processing faces appears to be explained by an inability to integrate individual features into an overall facial configuration, study results suggest.
Such defective facial processing may contribute to the social and interpersonal difficulties often seen in schizophrenia, say Steven Silverstein (University of Medicine and Dentistry of New Jersey, USA) and colleagues.
“Past studies in schizophrenia have demonstrated impairments in the processing of faces, although the factors responsible for this remain elusive,” they comment in the journal Psychological Medicine.
Studies of visual processing have demonstrated that recognition of details in objects and recognition of overall patterns utilize two different cognitive pathways.
This concept of "spatial frequency" is an important tool for understanding how individuals process faces, Silverstein and colleagues note.
It is believed that high spatial frequencies are used for perceiving details like eyes and lips, whereas larger-scale differences and the overall configuration of an object is perceived through low spatial frequencies.
To investigate how this might be compromised in schizophrenia, the researchers tested 14 patients with schizophrenia and 13 mentally healthy controls with an emotionally neutral, gender-discrimination task.
They used three conditions: faces characterized by the full spectrum of spatial frequencies (normal photographs); faces with only low spatial frequency information (blurred images with unclear features); and faces with high spatial frequency information (stenciled images with only features).
All participants were scanned using magnetic resonance imaging, focusing on the fusiform gyrus, which has been consistently linked with face processing.
The researchers found that patients with schizophrenia performed significantly worse at recognizing faces with low spatial frequency and normal photographs compared with mentally healthy controls.
By contrast, patients with schizophrenia actually scored slightly better at recognizing high spatial frequency faces than controls.
Surprisingly, patients with schizophrenia showed a higher activation in the fusiform gyrus than controls whilst performing tasks for both low spatial frequency and high spatial frequency.
The researchers suggest that this latter finding may represent a compensatory mechanism.
“It is possible that form-deficient information is reaching the fusiform area, requiring a greater than normal degree of feature assembly or analysis before a face representation is formed,” they comment.
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010
By Andrew Czyzewski