Source-reconstruction of event-related fields reveals hyperfunction and hypofunction of cortical circuits in antipsychotic-naive, first-episode schizophrenia patients during Mooney face processing

Abstract

Schizophrenia is characterized by dysfunctions in neural circuits that can be investigated with electrophysiological methods, such as EEG and MEG. In the present human study, we examined event-related fields (ERFs), in a sample of medication-naive, first-episode schizophrenia (FE-ScZ) patients (n = 14) and healthy control participants (n = 17) during perception of Mooney faces to investigate the integrity of neuromagnetic responses and their experience-dependent modification. ERF responses were analyzed for M100, M170, and M250 components at the sensor and source levels. In addition, we analyzed peak latency and adaptation effects due to stimulus repetition. FE-ScZ patients were characterized by significantly impaired sensory processing, as indicated by a reduced discrimination index (A'). At the sensor level, M100 and M170 responses in FE-ScZ were within the normal range, whereas the M250 response was impaired. However, source localization revealed widespread elevated activity for M100 and M170 in FE-ScZ and delayed peak latencies for the M100 and M250 responses. In addition, M170 source activity in FE-ScZ was not modulated by stimulus repetitions. The present findings suggest that neural circuits in FE-ScZ may be characterized by a disturbed balance between excitation and inhibition that could lead to a failure to gate information flow and abnormal spreading of activity, which is compatible with dysfunctional glutamatergic neurotransmission.

Keywords: ERFs; M170; MEG; Mooney faces; face processing; first-episode psychosis.

Figure 1.

Mooney stimuli: example trial sequence. A fixation cross, not represented in the figure, was shown between each trial.

Figure 2.

Corresponding ERF traces for all sensors and all trials. Black, Face condition; red, no-face condition.

Figure 3.

Sensor-level analysis. Shown are ERF topographical distributions for the M100, M170, and M250 for both controls and FE-ScZ (in femto-teslas, fT).

Figure 4.

Sensor-level statistics. Shown is the main effect of condition (face vs no-face) for the M100 (left), M170 (middle), and M250 (right). Top, Topoplot indicating the F-map distribution. Statistically significant channels are highlighted. *p < 0.01; x = p < 0.05. Bottom, Face and no-face ERFs averages over sensors showing a statistically significant F-value.

Figure 5.

Sensor-level statistics: Shown is the group × condition interaction for the M250. Left, F-value (top) and T-value (bottom) distribution highlighting, respectively, the statistically significant channels for the ANOVA and for the post hoc analysis. *p < 0.01; x = p < 0.05. Right, ERF averages for the face and no-face conditions in controls and FE-ScZ over sensors showing statistically significant effects.

Figure 6.

Source reconstructions: t-contrasts for face versus no-face. For M100: (1) left middle orbitofrontal lobe (−18, 50, −16); (2) right inferior frontal gyrus (pars triangularis; 48, 38, 2); (3) left precuneus (−8, −54, 14); (4) right fusiform gyrus (44, −34, −20); and (5) left fusiform gyrus (−44, −38, −20). For M170: (1) left parahippocampal gyrus (−22, −24, −22); (2) right cuneus (16, −70, 30); (3) left middle occipital gyrus (−24, −62, 32); (4) right postcentral gyrus (−62, −12, 26); (5) left postcentral gyrus (64, −10, 18); (6) right fusiform gyrus (42, −38, −24); and (7) left fusiform gyrus (−44, −40, 22). For M250: (1) right inferior frontal gyrus (pars triangularis; 50, 60, 4). L, Left hemisphere; R, right hemisphere.

Figure 7.

Source reconstructions of the face condition showing t-maps of FE-ScZ > controls (a) and controls > FE-ScZ (b). a, For M100: (1) left mid-orbitofrontal gyrus (−18, 50, −16); (2) left precuneus (−8, −52, 12); (3) right inferior frontal gyrus (pars triangularis; 54, 24, 4); (4) right fusiform gyrus (44, −34, −20); (5) right superior temporal lobe (56, −42, 14); (6) left inferior temporal gyrus (−42, −34, −18); (7) left rolandic operculum (−46, −28, 16); and (8) left calcarine cortex (−4, −92, −12). For M170: (1) left parahippocampal gyrus (−22, −24, −22); (2) right postcentral gyrus (64, −10, 18); (3) left postcentral (−62, −12, 26); (4) left fusiform gyrus (−44, −40, 22); (5) right fusiform gyrus (42, −38, −24); (6) right lingual gyrus (10, −82, −8); (7) right inferior occipital gyrus (38, −82, −16); (8) left lingual gyrus (−12, −94, −18); (9) right superior temporal gyrus (62, −42, 22); and (10) left superior temporal gyrus (−50, −36, 12). b, For M170: (1) left middle occipital gyrus (−24, −62, 32); (2) right cuneus (18, −68, 28). For M250: (1) right inferior frontal gyrus (pars triangularis; 50, 38, 2); (2) right middle frontal gyrus (26, 48, 2); and (3) left middle frontal gyrus (−26, 46, 2). L, Left hemisphere; R, right hemisphere.

Figure 8.

Source reconstruction for the M170. Shown are T-contrasts between the first (Half 1) and the second (Half 2) half of trials showing activity in: (1) left middle cingulate cortex (−4, 0, 34); (2) right middle cingulate cortex (4, −8, 32); (3) left middle frontal gyrus (−36, 26, −42); (4) left parahippocampal gyrus (−22, −8, −32); and (5) right fusiform gyrus (34, 0, −38). L, Left hemisphere; R, right hemisphere.