Browsing by Subject "VISUAL-ATTENTION"

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  • Kurki, Ilmari; Hyvarinen, Aapo; Henriksson, Linda (2022)
    Visual focal attention is both fast and spatially localized, making it challenging to investigate using human neu-roimaging paradigms. Here, we used a new multivariate multifocal mapping method with magnetoencephalog-raphy (MEG) to study how focal attention in visual space changes stimulus-evoked responses across the visual field. The observer's task was to detect a color change in the target location, or at the central fixation. Simulta-neously, 24 regions in visual space were stimulated in parallel using an orthogonal, multifocal mapping stimulus sequence. First, we used univariate analysis to estimate stimulus-evoked responses in each channel. Then we applied multivariate pattern analysis to look for attentional effects on the responses. We found that attention to a target location causes two spatially and temporally separate effects. Initially, attentional modulation is brief, observed at around 60-130 ms post stimulus, and modulates responses not only at the target location but also in adjacent regions. A later modulation was observed from around 200 ms, which was specific to the location of the attentional target. The results support the idea that focal attention employs several processing stages and suggest that early attentional modulation is less spatially specific than late.
  • Laasonen, Marja; Lahti-Nuuttila, Pekka; Leppämäki, Sami; Tani, Pekka; Wikgren, Jan; Harno, Hanna; Oksanen-Hennah, Henna; Pothos, Emmanuel; Cleeremans, Axel; Dye, Matthew W. G.; Cousineau, Denis; Hokkanen, Laura (2020)
    Two themes have puzzled the research on developmental and learning disorders for decades. First, some of the risk and protective factors behind developmental challenges are suggested to be shared and some are suggested to be specific for a given condition. Second, language-based learning difficulties like dyslexia are suggested to result from or correlate with non-linguistic aspects of information processing as well. In the current study, we investigated how adults with developmental dyslexia or ADHD as well as healthy controls cluster across various dimensions designed to tap the prominent non-linguistic theories of dyslexia. Participants were 18-55-year-old adults with dyslexia (n= 36), ADHD (n= 22), and controls (n= 35). Non-linguistic theories investigated with experimental designs included temporal processing impairment, abnormal cerebellar functioning, procedural learning difficulties, as well as visual processing and attention deficits. Latent profile analysis (LPA) was used to investigate the emerging groups and patterns of results across these experimental designs. LPA suggested three groups: (1) a large group with average performance in the experimental designs, (2) participants predominantly from the clinical groups but with enhanced conditioning learning, and (3) participants predominantly from the dyslexia group with temporal processing as well as visual processing and attention deficits. Despite the presence of these distinct patterns, participants did not cluster very well based on their original status, nor did the LPA groups differ in their dyslexia or ADHD-related neuropsychological profiles. Remarkably, the LPA groups did differ in their intelligence. These results highlight the continuous and overlapping nature of the observed difficulties and support the multiple deficit model of developmental disorders, which suggests shared risk factors for developmental challenges. It also appears that some of the risk factors suggested by the prominent non-linguistic theories of dyslexia relate to the general level of functioning in tests of intelligence.
  • Salmela, Viljami; Salo, Emma; Salmi, Juha; Alho, Kimmo (2018)
    The fronto-parietal attention networks have been extensively studied with functional magnetic resonance imaging (fMRI), but spatiotemporal dynamics of these networks are not well understood. We measured event-related potentials (ERPs) with electroencephalography (EEG) and collected fMRI data from identical experiments where participants performed visual and auditory discrimination tasks separately or simultaneously and with or without distractors. To overcome the low temporal resolution of fMRI, we used a novel ERP-based application of multivariate representational similarity analysis (RSA) to parse time-averaged fMRI pattern activity into distinct spatial maps that each corresponded, in representational structure, to a short temporal ERP segment. Discriminant analysis of ERP-fMRI correlations revealed 8 cortical networks-2 sensory, 3 attention, and 3 other-segregated by 4 orthogonal, temporally multifaceted and spatially distributed functions. We interpret these functions as 4 spatiotemporal components of attention: modality-dependent and stimulus-driven orienting, top-down control, mode transition, and response preparation, selection and execution.