Characterizing a snapshot of perceptual experience.

What can we perceive in a single glance of the visual world? Although this question appears rather simple, answering it has been remarkably difficult and controversial. Traditionally, researchers have tried to infer the nature of perceptual experience by examining how many objects and what types of objects are not fully encoded within a scene (e.g., failing to notice a bowl disappearing/changing). Here, we took a different approach and asked how much we could alter an entire scene before observers noticed those global alterations. Surprisingly, we found that observers could fixate on a scene for hundreds of milliseconds yet routinely fail to notice drastic changes to that scene (e.g., scrambling the periphery so no object can be identified, putting the center of 1 scene on the background of another scene). In addition, we also found that as observers allocate more attention to their periphery, their ability to notice these changes to a scene increases. Together, these results show that although a single snapshot of perceptual experience can be remarkably impoverished, it is also not a fixed constant and is likely to be continuously changing from moment to moment depending on attention. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Childhood maltreatment experiences are associated with altered diffusion in occipito-temporal white matter pathways.

BACKGROUND: Childhood maltreatment may contribute to brain alterations in posttraumatic stress disorder (PTSD). We previously found that PTSD was associated with white matter compromise, or lower fractional anisotropy (FA), in the left inferior longitudinal fasciculus (ILF). In this study, including non-PTSD controls, we examined whether ILF FA was associated with maltreatment exposures, including those that meet DSM-IV criterion A (physical abuse, sexual abuse) and those that typically do not (emotional abuse, emotional neglect, physical neglect). We hypothesized that lower FA would be associated with PTSD diagnosis and with both categories of maltreatment. METHODS: Ninety-three participants (51 female), ages 20-50, were enrolled, including 32 with lifetime DSM-IV PTSD, 27 trauma-exposed non-PTSD controls, and 34 healthy controls. Participants completed structured interviews, the Childhood Trauma Questionnaire (CTQ), and diffusion-weighted imaging (36 directions). Probabilistic tractography (using FreeSurfer's TRACULA) was used to assess diffusion metrics in the ILF. RESULTS: Contrary to our hypothesis, there was no significant effect of diagnostic group on FA. In contrast, higher CTQ scores were significantly associated with lower FA in the ILF bilaterally. This association of maltreatment with lower FA remained statistically significant after controlling for diagnostic group, and it was significant for both criterion-A-type and noncriterion-A-type maltreatment categories. CONCLUSIONS: This work contributes to a growing body of literature indicating that different forms of childhood maltreatment are associated with altered white matter microstructure in the ILF, an association pathway involved in integrating visual information from occipital regions with emotion processing functions of the anterior temporal lobe.