Browsing by Subject "P300"

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  • Bompada, Pradeep; Atac, David; Luan, Cheng; Andersson, Robin; Omella, Judit Domenech; Laakso, Emilia Ottosson; Wright, Jason; Groop, Leif; De Marinis, Yang (2016)
    Thioredoxin-interacting protein (TXNIP) has been shown to be associated with glucose-induced deterioration of pancreatic beta cell function in diabetes. However, whether epigenetic mechanisms contribute to the regulation of TXNIP gene expression by glucose is not clear. Here we studied how glucose exerts its effect on TXNIP gene expression via modulation of histone acetylation marks. To achieve this, we applied clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9) to knock out his tone acetyltransferase (HAT) p300 in a rat pancreatic beta cell line INS1 832/13. We also treated the cells and human islets with chemical inhibitors of HAT p300 and histone deacetylase (HDAC). In human islets, diabetes and high glucose resulted in elevated TXNIP and EP300 expression, and glucose-induced TXNIP expression could be reversed by p300 inhibitor C646. In INS1 832/13 cells, Ep300 knock-out by CRISPR/Cas9 elevated glucose-induced insulin secretion and greatly reduced glucose-stimulated Txnip expression and cell apoptosis. This effect could be ascribed to decrease in histone marks H3K9ac and H4ac at the promoter and first coding region of the Txnip gene. Histone marks H3K9ac and H4ac in the Txnip gene in the wild-type cells was inhibited by HDAC inhibitor at high glucose, which most likely was due to enhanced acetylation levels of p300 after HDAC inhibition; and thereby reduced p300 binding to the Txnip gene promoter region. Such inhibition was absent in the Ep300 knock-out cells. Our study provides evidence that histone acetylation serves as a key regulator of glucose-induced increase in TXNIP gene expression and thereby glucotoxicity-induced apoptosis. (C) 2016 Elsevier Ltd. All rights reserved.
  • Sokka, Laura; Leinikka, Marianne; Korpela, Jussi; Henelius, Andreas; Ahonen, Lauri; Alain, Claude; Alho, Kimmo; Huotilainen, Minna (2016)
    Individuals with job burnout symptoms often report having cognitive difficulties, but related electrophysiological studies are scarce. We assessed the impact of burnout on performing a visual task with varying memory loads, and on involuntary attention switch to distractor sounds using scalp recordings of event-related potentials (ERPs). Task performance was comparable between burnout and control groups. The distractor sounds elicited a P3a response, which was reduced in the burnout group. This suggests burnout-related deficits in processing novel and potentially important events during task performance. In the burnout group, we also observed a decrease in working-memory related P3b responses over posterior scalp and increase over frontal areas. These results suggest that burnout is associated with deficits in cognitive control needed to monitor and update information in working memory. Successful task performance in burnout might require additional recruitment of anterior regions to compensate the decrement in posterior activity. (C) 2016 Elsevier B.V. All rights reserved.
  • Helenius, Paivi; Laasonen, Marja; Hokkanen, Laura; Paetau, Ritva; Niemivirta, Markku (2010)
    The P3 response has been one of the most extensively studied event-related potential (ERP) components. Still, the exact functional role and cortical basis of P3 has remained unsettled. To explore the cortical processes underlying the generation of late positivities, we recorded the activation evoked by frequent Go and infrequent NoGo stimuli and correct versus erroneous responses using combined magnetoencephalography (MEG) and ERP measurements during a visual Go/NoGo task. The stimulus-locked signals in the ERP channels revealed an enhanced negative N2 and a prominent late positive component (LPC) after the complex NoGo stimuli associated with successfully withheld responses. The response-locked ERP signals revealed error-related negativity (ERN) and positivity (Pe) after erroneous responses. The positive LPC and Pe components were coupled with functionally and temporally comparable MEG signals. This MEG activation detected during the positive components was localized bilaterally in the posterior temporal cortex. In the response-locked averages, the temporal activity was enhanced around 200 ms after a commission of an error. In the stimulus-locked averages, the activation was also enhanced after infrequent NoGo stimuli around 500 ms after stimulus onset and delayed about 80 ms for the initially miscategorized NoGo stimuli accompanied by erroneous response. The results suggest that the cortical correlates of Pe are not specifically related to commission of an error, but both the LPC and Pe components, and bilateral temporal cortices, are more generally involved in stimulus-driven attentional processing evoked by unexpected stimuli. The negative ERP components evoked by NoGo stimuli (N2) and erroneous responses (ERN) were found to be associated with partly non-overlapping neural sources.
  • Kangassalo, Lauri; Spape, Michiel; Ruotsalo, Tuukka (2020)
    Brain-computer interfaces enable active communication and execution of a pre-defined set of commands, such as typing a letter or moving a cursor. However, they have thus far not been able to infer more complex intentions or adapt more complex output based on brain signals. Here, we present neuroadaptive generative modelling, which uses a participant's brain signals as feedback to adapt a boundless generative model and generate new information matching the participant's intentions. We report an experiment validating the paradigm in generating images of human faces. In the experiment, participants were asked to specifically focus on perceptual categories, such as old or young people, while being presented with computer-generated, photorealistic faces with varying visual features. Their EEG signals associated with the images were then used as a feedback signal to update a model of the user's intentions, from which new images were generated using a generative adversarial network. A double-blind follow-up with the participant evaluating the output shows that neuroadaptive modelling can be utilised to produce images matching the perceptual category features. The approach demonstrates brain-based creative augmentation between computers and humans for producing new information matching the human operator's perceptual categories.
  • Puro, Kaisa (Helsingin yliopisto, 2020)
    Objectives. Temperament refers to person’s innate and relatively stable tendencies to react and act. Previous studies suggest that various temperamental traits are associated with learning later in childhood but less is known about the effects of infant temperament on learning early in childhood, and the evidence is somewhat contradictory. In this study, temperament is examined via three dimensions, surgency, negative affectivity, and regulation. The dimension of regulation is related to processes of attention, of which involuntary attention shift is of interest in this study. The research question is whether the dimensions of temperament assessed in infancy either alone or through the mediating effect of involuntary attention shifting are related to a child’s information processing skills at 28 months of age. It is assumed that an easily distractible baby may not be able to benefit from learning situations with an adult as effectively as a baby with more stable temperamental traits. Methods. The research data was gathered in the Lukivauva follow-up study, which examines the child’s linguistic development and hereditary risks of reading difficulties from birth. Approximately 200 families were recruited to the Lukivauva project during 2015–2017 before the birth of their children, and 73 of these children were selected to participate in this study. At six months of age, parents assessed the child’s temperament with an IBQ-R-VSF questionnaire and children’s involuntary attention shift was assessed with an EEG auditory test of novel-sounds. When children were 28 months of age, their auditory information processing performance was assessed with Reynell’s test and visuo-spatial performance with WPPSI-III-test. Results. Of the three dimensions of temperament and the measures of cognitive performance the only statistically significant association emerged between stronger negative affectivity and poorer visuo-spatial performance. P300 response was not associated with any of the dimensions of temperament and it did not predict auditory or visuo-spatial information processing skills in toddlerhood. Conclusions. The temperamental dimensions of six-month-old infants do not appear to be associated with involuntary attention shifting. Similarly, the temperament of the infant or involuntary attention shifting do not appear to be related to information processing in toddlerhood. The associations between temperament, attention processes, and learning in early childhood require further research. It is important to consider other developmental factors as well and their effects on the relationship between temperament, attentional processes, and learning.