Browsing by Subject "capacity"

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  • Luostarinen, Maaria (Helsingin yliopisto, 2018)
    Visual working memory refers to the cognitive system responsible for the short-term storage and manipulation of visual information. Prevailing view suggests that there is a trade-off between memory capacity and precision: we can hold more items in memory with lower precision or fewer items with higher precision. Recent functional magnetic resonance imaging (fMRI) studies suggest distributed visual working memory representations in multiple brains areas from sensory visual to the parietal and frontal cortex. This thesis consists of a visual working memory fMRI study, using human faces as stimuli. The purpose of this thesis was to examine the visual working memory precision for angry, neutral and happy faces and the memory representations in the face network, and to directly compare the neural activity while participants discriminated and memorized faces. The participants discriminated and remembered faces precisely and were highly aware of occasional memory lapses, as shown by the confidence ratings of responses. In the primary visual cortex (V1) and fusiform face area (FFA), happy faces elicited higher brain activation than angry or neutral faces. The multivariate analysis of fMRI activation patterns showed correlations between the perception and memory tasks in these areas. Overall, the activations and correlations were higher in the right hemisphere, as expected. The correlations between perception and memory conditions were surprisingly low given the identical stimuli in these conditions. Even small positive correlations in the right V1 and FFA, however, support their role in maintaining facial information in visual working memory.
  • Saarilahti, Martti (Suomen metsätieteellinen seura, 1988)
  • Cosens, Barbara; Ruhl, J. B.; Soininen, Niko; Gunderson, Lance; Belinskij, Antti; Blenckner, Thorsten; Camacho, Alejandro E.; Chaffin, Brian C.; Craig, Robin Kundis; Doremus, Holly; Glicksman, Robert; Heiskanen, Anna-Stiina; Larson, Rhett; Similä, Jukka (National Academy of Sciences, 2021)
    Proceedings of the National Academy of Sciences Sep 2021, 118 (36) e2102798118
    The speed and uncertainty of environmental change in the Anthropocene challenge the capacity of coevolving social–ecological–technological systems (SETs) to adapt or transform to these changes. Formal government and legal structures further constrain the adaptive capacity of our SETs. However, new, self-organized forms of adaptive governance are emerging at multiple scales in natural resource-based SETs. Adaptive governance involves the private and public sectors as well as formal and informal institutions, self-organized to fill governance gaps in the traditional roles of states. While new governance forms are emerging, they are not yet doing so rapidly enough to match the pace of environmental change. Furthermore, they do not yet possess the legitimacy or capacity needed to address disparities between the winners and losers from change. These emergent forms of adaptive governance appear to be particularly effective in managing complexity. We explore governance and SETs as coevolving complex systems, focusing on legal systems to understand the potential pathways and obstacles to equitable adaptation. We explore how governments may facilitate the emergence of adaptive governance and promote legitimacy in both the process of governance despite the involvement of nonstate actors, and its adherence to democratic values of equity and justice. To manage the contextual nature of the results of change in complex systems, we propose the establishment of long-term study initiatives for the coproduction of knowledge, to accelerate learning and synergize interactions between science and governance and to foster public science and epistemic communities dedicated to navigating transitions to more just, sustainable, and resilient futures.
  • Rouhinen, Santeri; Siebenhühner, Felix; Palva, J. Matias; Palva, Satu (2020)
    The capacity of visual attention determines how many visual objects may be perceived at any moment. This capacity can be investigated with multiple object tracking (MOT) tasks, which have shown that it varies greatly between individuals. The neuronal mechanisms underlying capacity limits have remained poorly understood. Phase synchronization of cortical oscillations coordinates neuronal communication within the fronto-parietal attention network and between the visual regions during endogenous visual attention. We tested a hypothesis that attentional capacity is predicted by the strength of pretarget synchronization within attention-related cortical regions. We recorded cortical activity with magneto- and electroencephalography (M/EEG) while measuring attentional capacity with MOT tasks and identified large-scale synchronized networks from source-reconstructed M/EEG data. Individual attentional capacity was correlated with load-dependent strengthening of theta (3-8 Hz), alpha (8-10 Hz), and gamma-band (30-120 Hz) synchronization that connected the visual cortex with posterior parietal and prefrontal cortices. Individual memory capacity was also preceded by crossfrequency phase-phase and phase-amplitude coupling of alpha oscillation phase with beta and gamma oscillations. Our results show that good attentional capacity is preceded by efficient dynamic functional coupling and decoupling within brain regions and across frequencies, which may enable efficient communication and routing of information between sensory and attentional systems.