Sensory contributions to impaired emotion processing in schizophrenia

Abstract

Both emotion and visual processing deficits are documented in schizophrenia, and preferential magnocellular visual pathway dysfunction has been reported in several studies. This study examined the contribution to emotion-processing deficits of magnocellular and parvocellular visual pathway function, based on stimulus properties and shape of contrast response functions. Experiment 1 examined the relationship between contrast sensitivity to magnocellular- and parvocellular-biased stimuli and emotion recognition using the Penn Emotion Recognition (ER-40) and Emotion Differentiation (EMODIFF) tests. Experiment 2 altered the contrast levels of the faces themselves to determine whether emotion detection curves would show a pattern characteristic of magnocellular neurons and whether patients would show a deficit in performance related to early sensory processing stages. Results for experiment 1 showed that patients had impaired emotion processing and a preferential magnocellular deficit on the contrast sensitivity task. Greater deficits in ER-40 and EMODIFF performance correlated with impaired contrast sensitivity to the magnocellular-biased condition, which remained significant for the EMODIFF task even when nonspecific correlations due to group were considered in a step-wise regression. Experiment 2 showed contrast response functions indicative of magnocellular processing for both groups, with patients showing impaired performance. Impaired emotion identification on this task was also correlated with magnocellular-biased visual sensory processing dysfunction. These results provide evidence for a contribution of impaired early-stage visual processing in emotion recognition deficits in schizophrenia and suggest that a bottom-up approach to remediation may be effective.

Fig. 1.

Examples of faces used in experiment 2. Faces were presented at different contrasts, with several of the contrasts shown here.

Fig. 2.

Psychophysical contrast sensitivity functions for patients with schizophrenia and healthy controls. Values are plotted as contrast sensitivity, defined as the reciprocal of contrast threshold percentage. Results at the lower spatial frequencies are indicative of performance of the magnocellular system, and results at the higher spatial frequencies are indicative of performance of the parvocellular system. **P = .005.

Fig. 3.

Percent correct on the Penn Emotion Recognition (ER-40) (A) and Penn Emotion Differentiation (EMODIFF) (B) tasks. Relationships between contrast sensitivity for the magnocellular-biased low spatial frequency (0.5 cycles/degree) grating and performance on the ER-40 (C) or EMODIFF (D) tasks. Triangles correspond to patients and circles to controls. *P < .05; **P < .001.

Fig. 4.

Steady-state visual evoked potential (ssVEP) signal-to-noise ratios for patients with schizophrenia and healthy controls in test conditions using depth of modulation (% luminance modulation) to emphasize the magnocellular (A) or parvocellular (B) visual pathways. Patients needed 16% contrast to obtain the same response as controls at 8% contrast (C). *P ≤ .05.

Fig. 5.

Sensitivity (A′) for detection of happy (A), sad (B), or neutral (C) faces at different contrasts. Patients needed 8% contrast to obtain the same sensitivity as controls at 4% contrast (D). *P < .01; **P < .001.

Fig. 6.

Percent correct across emotions for faces at different contrasts (A). Patients needed 8% contrast to obtain the same response as controls for 4% contrast (B). *P < .05; **P < .001.