Psychological dissociation and temporal integration/segregation across the senses: An experimental study.

There are no studies that have experimentally tested how temporal integration/segregation of sensory inputs might be linked to the emergence of dissociative experiences and alterations of emotional functioning. Thirty-six participants completed 3 sensory integration tasks. Psychometric thresholds were estimated as indexes of temporal integration/segregation processes. We collected self-report measures of pre-task trait levels of dissociation, as well as pre- post-task changes in both dissociation and emotionality. An independent sample of 21 subjects completed a control experiment administering the Attention Network Test. Results showed: (i) a significant increase of dissociative experiences after the completion of sensory integration tasks, but not after the ANT task; (ii) that subjective thresholds predicted the emergence of dissociative states; (iii) temporal integration efforts affected positive emotionality, which was explained by the extent of task-dependent dissociative states. The present findings reveal that dissociation could be understood in terms of an imbalance between "hyper-segregation" and "hyper-integration" processes.

Electrophysiological signatures of visual temporal processing deficits in developmental dyslexia.

Developmental dyslexia (DD) is a common neurodevelopmental disorder that affects reading ability despite normal intelligence and education. In search of core deficits, previous evidence has linked DD with impairments in temporal aspects of perceptual processing, which might underlie phonological deficits as well as inefficient graphemic parsing during reading. However, electrophysiological evidence for atypical temporal processing in DD is still scarce in the visual modality. Here, we investigated the efficiency of both temporal segregation and integration of visual information by means of event-related potentials (ERPs). We confirmed previous evidence of a selective segregation deficit in dyslexia for stimuli presented in rapid succession (<80 ms), despite unaffected integration performance. Importantly, we found a reduced N1 amplitude in DD, a component related to the allocation of attentional resources, which was independent of task demands (i.e., evident in both segregation and integration). In addition, the P3 amplitude, linked to working memory and processing load, was modulated by task demands in controls but not in individuals with DD. These results suggest that atypical attentional sampling in dyslexia might weaken the quality of information stored in visual working memory, leading to behavioral and electrophysiological signatures of atypical temporal segregation. These results are consistent with some existing theories of dyslexia, such as the magnocellular theory and the "Sluggish Attentional Shifting" framework, and represent novel evidence for neural correlates of decreased visual temporal resolution in DD.

Periodic and Aperiodic EEG Features as Potential Markers of Developmental Dyslexia.

Developmental Dyslexia (DD) is a neurobiological condition affecting the ability to read fluently and/or accurately. Analyzing resting-state electroencephalographic (EEG) activity in DD may provide a deeper characterization of the underlying pathophysiology and possible biomarkers. So far, studies investigating resting-state activity in DD provided limited evidence and did not consider the aperiodic component of the power spectrum. In the present study, adults with (n = 26) and without DD (n = 31) underwent a reading skills assessment and resting-state EEG to investigate potential alterations in aperiodic activity, their impact on the periodic counterpart and reading performance. In parieto-occipital channels, DD participants showed a significantly different aperiodic activity as indexed by a flatter and lower power spectrum. These aperiodic measures were significantly related to text reading time, suggesting a link with individual differences in reading difficulties. In the beta band, the DD group showed significantly decreased aperiodic-adjusted power compared to typical readers, which was significantly correlated to word reading accuracy. Overall, here we provide evidence showing alterations of the endogenous aperiodic activity in DD participants consistently with the increased neural noise hypothesis. In addition, we confirm alterations of endogenous beta rhythms, which are discussed in terms of their potential link with magnocellular-dorsal stream deficit.