Wider and Stronger Inhibitory Ring of the Attentional Focus in Schizophrenia

The effect of avatar identity on spontaneous perspective-taking in patients with schizophrenia

Controversy exists regarding whether the spontaneity of altercentric intrusion is impaired in patients with schizophrenia during implicit visual perspective-taking tasks. This study explored the characteristics of spontaneous visual perspective-taking in patients with schizophrenia and the effect of an avatar identity on their perspective-taking. We recruited 65 patients with schizophrenia and 65 healthy participants to complete 4 visual perspective-taking experiments for uncued other-avatar and self-avatar tasks and cued other-avatar and self-avatar tasks. In uncued other-avatar experiments, healthy controls showed a significant reduction in accuracy and an increase in response latency when the number of visible discs differed from that seen by the other-avatar (inconsistent condition), indicating altercentric intrusion. However, patients with schizophrenia did not exhibit this effect. In uncued self-avatar experiments, when the avatar was defined as the participant themselves, patients with schizophrenia did not show spontaneous perspective-taking. However, in cued other-avatar experiments, they showed altercentric intrusion in response latency, and in cued self-avatar experiments, they showed altercentric intrusion in accuracy and response latency. These results suggest that patients with schizophrenia have the tendency to spontaneously adopt the perspective of others, which is predicated on their awareness of the existence of perspectives. In addition, the avatar's identity as a stranger hinders the spontaneous perspective-taking processes in patients with schizophrenia.

Individual Alpha Frequency Contributes to the Precision of Human Visual Processing

Brain oscillatory activity within the alpha band has been associated with a wide range of processes encompassing perception, memory, decision-making, and overall cognitive functioning. Individual alpha frequency (IAF) is a specific parameter accounting for the mean velocity of the alpha cycling activity, conventionally ranging between ∼7 and ∼13 Hz. One influential hypothesis has proposed a fundamental role of this cycling activity in the segmentation of sensory input and in the regulation of the speed of sensory processing, with faster alpha oscillations resulting in greater temporal resolution and more refined perceptual experience. However, although several recent theoretical and empirical studies would support this account, contradictory evidence suggests caution and more systematic approaches in the assessment and interpretation of this hypothesis. For example, it remains to be explored to what degree IAF shapes perceptual outcomes. In the present study, we investigated whether inter-individual differences in bias-free visual contrast detection threshold in a large sample of individuals in the general population (n = 122) could be explained by inter-individual differences in alpha pace. Our results show that the contrast needed to correctly identify target stimuli (individual perceptual threshold) is associated with alpha peak frequency (not amplitude). Specifically, individuals who require reduced contrast show higher IAF than individuals requiring higher contrasts. This suggests that inter-individual differences in alpha frequency contribute to performance variability in low-level perceptual tasks, supporting the hypothesis that IAF underlies a fundamental temporal sampling mechanism that shapes visual objective performance, with higher frequencies promoting enhanced sensory evidence per time unit.

Transcranial magnetic stimulation on the right dorsal attention network modulates the center-surround profile of the attentional focus

Psychophysical observations indicate that the spatial profile of visuospatial attention includes a central enhancement around the attentional focus, encircled by a narrow zone of reduced excitability in the immediate surround. This inhibitory ring optimally amplifies relevant target information, likely stemming from top-down frontoparietal recurrent activity modulating early visual cortex activations. However, the mechanisms through which neural suppression gives rise to the surrounding attenuation and any potential hemispheric specialization remain unclear. We used transcranial magnetic stimulation to evaluate the role of two regions of the dorsal attention network in the center-surround profile: the frontal eye field and the intraparietal sulcus. Participants performed a psychophysical task that mapped the entire spatial attentional profile, while transcranial magnetic stimulation was delivered either to intraparietal sulcus or frontal eye field on the right (Experiment 1) and left (Experiment 2) hemisphere. Results showed that stimulation of right frontal eye field and right intraparietal sulcus significantly changed the center-surround profile, by widening the inhibitory ring around the attentional focus. The stimulation on the left frontal eye field, but not left intraparietal sulcus, induced a general decrease in performance but did not alter the center-surround profile. Results point to a pivotal role of the right dorsal attention network in orchestrating inhibitory spatial mechanisms required to limit interference by surrounding distractors.