Psychogenic Non-epileptic Seizures (PNES) are ‘medically unexplained’ seizure-like episodes which superficially resemble epileptic seizures but which are not caused by epileptiform discharges in the brain. While many experts see PNES disorder as a multifactorial biopsychosocial condition, little is known about the neurobiological processes which may predispose, precipitate and/or perpetuate PNES symptomology. This systematic meta-review advances our knowledge and understanding of the neurobiological correlates of PNES by providing an up-to-date assessment of neuroimaging studies performed on individuals with PNES. Although the results presented appear inconclusive, they are consistent with an association between structural and functional brain abnormalities and PNES. These findings have implications for the way in which we think about this “medically unexplained” disorder and how we communicate the diagnosis to patients. However, it is also evident that neuroimaging studies in this area suffer from a number of significant limitations and future larger studies will need to better address these if we are to improve our understanding of the neurobiological correlates of predisposition to and/or manifestation of PNES.
Psychogenic non-epileptic seizures (PNES) are often viewed as manifestations of altered motor and sensory function resulting from psychological responses to adverse experiences. Yet many patients and non-expert healthcare professionals find it difficult to understand how severe disturbances in normal neurological functioning can solely result from underlying psychological mechanisms to the exclusion of other physical causes. Perhaps importantly, recent advances using neuroimaging techniques point to possible structural and functional correlates in PNES. In an attempt to further our understanding of the neurobiological correlates of this condition, we compared the brain scans of 20 patients with PNES (14 females, mean age 41.05, range 19-62) and 20 age- and gender-matched healthy controls (14 females, mean age 40.65, range 21-61) to investigate group differences for cortical thickness and gyrification patterns using FreeSurfer. Compared to controls, patients with PNES showed cortical thickness increases in motor, sensory and occipital areas as well as cortical thickness decreases in temporal and frontal brain regions. In addition, we observed age-related changes in cortical thickness in the right lateral occipital area in PNES. However, contrary to our prediction that atypical gyrification may be present, we did not find any evidence of abnormalities on a measure thought to reflect prenatal and early childhood cortical development and organization. Nor did we find significant correlations between cortical thickness results and clinical features. These findings partly corroborate, but also differ from previous morphometric studies in PNES. These inconsistencies likely reflect the aetiology and phenomenological heterogeneity of PNES.
EEG methods offer a promising approach to study the development of attention or attention‐related processes such as change‐detection and attentional capture. However, the development of these attention processes from early to middle childhood is not well understood. In the current study, we utilized a passive three‐stimulus oddball paradigm to examine age‐related changes in auditory change‐detection and attentional capture in a large sample of children across childhood (N = 475; 249 female, 226 male; Mage = 6.71; SDage = 2.22; Rangeage = 4.01–11.5 years). Conventional ERP analyses revealed no age‐related changes in change detection (mismatch negativity) and attentional capture (P3a) components, but we observed age‐related reductions in late automatic processing of auditory change (late discriminative negativity). However, when utilizing time‐frequency analyses, we observed developmental increases in frontocentral signal strength (power) and consistency (inter‐trial phase synchrony) in delta and theta bands in response to novel sounds. Such frontocentral delta/theta responses have been linked in prior work to cognitive control. To further examine this possibility, we examined relations with inhibitory control. Results revealed that increased consistency in theta in response to novel sounds was related to improved inhibitory control. Together, our results advance our understanding of the development of attention in childhood. Moreover, they demonstrate the contributions of time‐frequency approaches to studying neurocognitive development. Finally, our results highlight the utility of neuroimaging paradigms that have low cognitive and motor demands to study the development of psychological processes.
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