Browsing by Subject "MEMORY"

Sort by: Order: Results:

Now showing items 1-20 of 39
  • Kukli, Kaupo; Kemell, Marianna; Castan, Helena; Duenas, Salvador; Seemen, Helina; Rähn, Mihkel; Link, Joosep; Stern, Raivo; Ritala, Mikko; Leskelä, Markku (2018)
    Nanocrystalline HfO2:Al2O3 mixture films and nanolaminates were grown by atomic layer deposition at 350 degrees C from metal chloride precursors and water. Formation of metastable HfO2 polymorphs versus monoclinic phase was affected by the relative amount and thickness of constituent oxide layers. The films exhibited saturative magnetization and charge polarization in externally applied fields at room temperature. The films also demonstrated resistive switching behavior with considerable window between low and high resistance states. (C) The Author(s) 2018. Published by ECS.
  • Jansson-Verkasalo, Eira; Ruusuvirta, Timo; Huotilainen, Minna; Alku, Paavo; Kushnerenko, Elena; Suominen, Kalervo; Rytky, Seppo; Luotonen, Mirja; Kaukola, Tuula; Tolonen, Uolevi; Hallman, Mikko (2010)
  • Sarkamo, Teppo; Tervaniemi, Mari; Soinila, Seppo; Autti, Taina; Silvennoinen, Heli M.; Laine, Matti; Hietanen, Marja; Pihko, Elina (2010)
    Acquired amusia is a common disorder after damage to the middle cerebral artery (MCA) territory. However, its neurocognitive mechanisms, especially the relative contribution of perceptual and cognitive factors, are still unclear. We studied cognitive and auditory processing in the amusic brain by performing neuropsychological testing as well as magnetoencephalography (MEG) measurements of frequency and duration discrimination using magnetic mismatch negativity (MMNm) recordings. Fifty-three patients with a left (n = 24) or right (n = 29) hemisphere MCA stroke (MRI verified) were investigated 1 week, 3 months, and 6 months after the stroke. Amusia was evaluated using the Montreal Battery of Evaluation of Amusia (MBEA). We found that amusia caused by right hemisphere damage (RHD), especially to temporal and frontal areas, was more severe than amusia caused by left hemisphere damage (LHD). Furthermore, the severity of amusia was found to correlate with weaker frequency MMNm responses only in amusic RHD patients. Additionally, within the RHD subgroup, the amusic patients who had damage to the auditory cortex (AC) showed worse recovery on the MBEA as well as weaker MMNm responses throughout the 6-month follow-up than the non-amusic patients or the amusic patients without AC damage. Furthermore, the amusic patients both with and without AC damage performed worse than the non-amusic patients on tests of working memory, attention, and cognitive flexibility. These findings suggest domain-general cognitive deficits to be the primary mechanism underlying amusia without AC damage whereas amusia with AC damage is associated with both auditory and cognitive deficits.
  • Lappi, Otto; Lehtonen, Esko; Pekkanen, Jami; Itkonen, Teemu (2013)
  • Rummukainen, Olli; Radun, Jenni; Virtanen, Toni; Pulkki, Ville (2014)
  • Yeo, L.; Pujol-Autonell, I.; Baptista, R.; Eichmann, M.; Kronenberg-Versteeg, D.; Heck, S.; Dolton, G.; Sewell, A. K.; Härkönen, T.; Mikk, M. -L.; Toppari, J.; Veijola, R.; Knip, M.; Ilonen, J.; Peakman, M. (2020)
    In type 1 diabetes (T1D), autoreactive cytotoxic CD8(+) T cells are implicated in the destruction of insulin-producing beta cells. The HLA-B*3906 and HLA-A*2402 class I genes confer increased risk and promote early disease onset, suggesting that CD8(+) T cells that recognize peptides presented by these class I molecules on pancreatic beta cells play a pivotal role in the autoimmune response. We examined the frequency and phenotype of circulating preproinsulin (PPI)-specific and insulin B (InsB)-specific CD8(+) T cells in HLA-B*3906(+) children newly diagnosed with T1D and in high-risk HLA-A*2402(+) children before the appearance of disease-specific autoantibodies and before diagnosis of T1D. Antigen-specific CD8(+) T cells were detected using human leucocyte antigen (HLA) class I tetramers and flow cytometry was used to assess memory status. In HLA-B*3906(+) children with T1D, we observed an increase in PPI5-12-specific transitional memory CD8(+) T cells compared to non-diabetic, age- and HLA-matched subjects. Furthermore, PPI5-12-specific CD8(+) T cells in HLA-B*3906(+) children with T1D showed a significantly more antigen-experienced phenotype compared to polyclonal CD8(+) T cells. In longitudinal samples from high-risk HLA-A*2402(+) children, the percentage of terminal effector cells within the InsB(15-24)-specific CD8(+) T cells was increased before diagnosis relative to samples taken before the appearance of autoantibodies. This is the first study, to our knowledge, to report HLA-B*3906-restricted autoreactive CD8(+) T cells in T1D. Collectively, our results provide evidence that beta cell-reactive CD8(+) T cells restricted by disease-associated HLA class I molecules display an antigen-experienced phenotype and acquire enhanced effector function during the period leading to clinical diagnosis, implicating these cells in driving disease.
  • Kalakoski, Virpi; Henelius, Andreas; Oikarinen, Emilia; Ukkonen, Antti; Puolamäki, Kai (2019)
    Today's ever-increasing amount of data places new demands on cognitive ergonomics and requires new design ideas to ensure successful human-data interaction. Our aim was to identify the cognitive factors that must be considered when designing systems to improve decision-making based on large amounts of data. We constructed a task that simulates the typical cognitive demands people encounter in data analysis situations. We demonstrate some essential cognitive limitations using a behavioural experiment with 20 participants. The studied task presented the participants with critical and noncritical attributes that contained information on two groups of people. They had to select the response option (group) with the higher level of critical attributes. The results showed that accuracy of judgement decreased as the amount of information increased, and that judgement was affected by irrelevant information. Our results thus demonstrate critical cognitive limitations when people utilise data and suggest a cognitive bias in data-based decision-making. Therefore, when designing for cognition, we should consider the human cognitive limitations that are manifested in a data analysis context. Furthermore, we need general cognitive ergonomic guidelines for design that support the utilisation of data and improve data-based decision-making.
  • Kallio, Eeva-Liisa; Öhman, Hanna; Kautiainen, Hannu; Hietanen, Marja; Pitkala, Kaisu (2017)
    Background: Cognitive training (CT) refers to guided cognitive exercises designed to improve specific cognitive functions, as well as enhance performance in untrained cognitive tasks. Positive effects of CT on cognitive functions in healthy elderly people and persons with mild cognitive impairment have been reported, but data regarding the effects of CT in patients with dementia is unclear. Objective: We systematically reviewed the current evidence from randomized controlled trials (RCTs) to find out if CT improves or stabilizes cognition and/or everyday functioning in patients with mild and moderate Alzheimer's disease. Results: Altogether, 31 RCTs with CT as either the primary intervention or part of a broader cognitive or multi-component intervention were found. A positive effect was reported in 24 trials, mainly on global cognition and training-specific tasks, particularly when more intensive or more specific CT programs were used. Little evidence of improved everyday functioning was found. Conclusions: Despite some positive findings, the inaccurate definitions of CT, inadequate sample sizes, unclear randomization methods, incomplete datasets at follow-up and multiple testing may have inflated the results in many trials. Future high quality RCTs with appropriate classification and specification of cognitive interventions are necessary to confirm CT as an effective treatment option in Alzheimer's disease.
  • Sarkamo, Teppo (2018)
    Music has the capacity to engage auditory, cognitive, motor, and emotional functions across cortical and subcortical brain regions and is relatively preserved in aging and dementia. Thus, music is a promising tool in the rehabilitation of aging-related neurological illnesses, such as stroke and Alzheimer disease. As the population ages and the incidence and prevalence of these illnesses rapidly increases, music-based interventions that are enjoyable and effective in the everyday care of the patients are needed. In addition to formal music therapy, musical leisure activities, such as music listening and singing, which patients can do on their own or with a caregiver, are a promising way to support psychological well-being during aging and in neurological rehabilitation. This review article provides an overview of current evidence on the cognitive, emotional, and neural effects of musical leisure activities both during normal aging and in the rehabilitation and care of stroke patients and people with dementia. (C) 2017 Elsevier Masson SAS. All rights reserved.
  • Popova, Dina; Agustsdottir, Arna; Lindholm, Jesse; Mazulis, Warns; Akamine, Yumiko; Castren, Eero; Karpova, Nina N. (2014)
  • Rikandi, Eva; Mantyla, Teemu; Lindgren, Maija; Kieseppa, Tuula; Suvisaari, Jaana; Raij, Tuukka T. (2018)
    Background: Functional connectivity is altered in psychotic disorders. Multiple findings concentrate on the default mode network, anchored on the precuneus-posterior cingulate cortex (PC-PCC). However, the nature of the alterations varies between studies and connectivity alterations have not been studied during an ecologically valid natural stimulus. In the present study, we investigated the functional and structural connectivity of a PC-PCC region, where functioning differentiated first-episode psychosis patients from control subjects during free viewing of a movie in our earlier study. Methods: 14 first-episode psychosis patients and 12 control subjects were imaged with GE 3T, and 29 patients and 19 control subjects were imaged with a Siemens Skyra 3T scanner while watching scenes from the movie Alice in Wonderland. Group differences in functional connectivity were analysed for both scanners separately and results were compared to identify any overlap. Diffusion tensor measures of 26 patients and 19 control subjects were compared for the related white matter tracts, identified by deterministic tractography. Results: Functional connectivity was increased in patients across scanners between the midline regions of the PC-PCC and the anterior cingulate cortex-medial prefrontal cortex (ACC-mPFC). We found no group differences in any of the diffusion tensor imaging measures. Conclusions: Already in the early stages of psychosis functional connectivity between the midline structures of the PC-PCC and the ACC-mPFC is consistently increased during naturalistic stimulus. (c) 2018 Elsevier B.V. All rights reserved.
  • Leliaert, Jonathan; Van de Wiele, Ben; Vansteenkiste, Arne; Laurson, Lasse; Durin, Gianfranco; Dupre, Luc; Van Waeyenberge, Bartel (2016)
    The motion of domain walls in magnetic materials is a typical example of a creep process, usually characterised by a stretched exponential velocity-force relation. By performing large-scale micromagnetic simulations, and analyzing an extended 1D model which takes the effects of finite temperatures and material defects into account, we show that this creep scaling law breaks down in sufficiently narrow ferromagnetic strips. Our analysis of current-driven transverse domain wall motion in disordered Permalloy nanostrips reveals instead a creep regime with a linear dependence of the domain wall velocity on the applied field or current density. This originates from the essentially point-like nature of domain walls moving in narrow, line-like disordered nanostrips. An analogous linear relation is found also by analyzing existing experimental data on field-driven domain wall motion in perpendicularly magnetised media.
  • Virtala, Paula; Huotilainen, Minna; Lilja, Esa; Ojala, Juha; Tervaniemi, Mari (2018)
    GUITAR DISTORTION USED IN ROCK MUSIC MODIFIES a chord so that new frequencies appear in its harmonic structure. A distorted dyad (power chord) has a special role in heavy metal music due to its harmonics that create a major third interval, making it similar to amajor chord. We investigated how distortion affects cortical auditory processing of chords in musicians and nonmusicians. Electric guitar chords with or without distortion and with or without the interval of the major third (i.e., triads or dyads) were presented in an oddball design where one of them served as a repeating standard stimulus and others served as occasional deviants. This enabled the recording of event-related potentials (ERPs) of the electroencephalogram (EEG) related to deviance processing (the mismatch negativity MMN and the attention-related P3a component) in an ignore condition. MMN and P3a responses were elicited in most paradigms. Distorted chords in a non-distorted context only elicited early P3a responses. However, the power chord did not demonstrate a special role in the level of the ERPs. Earlier and larger MMN and P3a responses were elicited when distortion was modified compared to when only harmony (triad vs. dyad) was modified between standards and deviants. The MMN responses were largest when distortion and harmony deviated simultaneously. Musicians demonstrated larger P3a responses than nonmusicians. The results suggest mostly independent cortical auditory processing of distortion and harmony in Western individuals, and facilitated chord change processing in musicians compared to nonmusicians. While distortion has been used in heavy rock music for decades, this study is among the first ones to shed light on its cortical basis.
  • Ämmälä, Antti-Jussi; Urrila, Anna-Sofia; Lahtinen, Aleksandra; Santangeli, Olena; Hakkarainen, Antti; Kantojärvi, Katri; Castaneda, Anu E.; Lundbom, Nina; Marttunen, Mauri; Paunio, Tiina (2019)
    Objectives: This study aimed to test the hypothesis that sleep and depression have independent effects on brain development and plasticity in adolescents, and that these changes are reflected in changes in the epigenome. Methods: Participants were 17 medication-free adolescent boys (age 16.05 +/- 0.80 years, mean +/- standard deviation (SD); eight cases with depression and sleep symptoms, nine healthy controls). Sleep was assessed by polysomnography recordings and the Pediatric Daytime Sleepiness Scale (PDSS) and Athens Insomnia Scale (AIS). Participants underwent a clinical evaluation. DNA methylation of blood leukocytes was measured by Illumina 450K array, and Ingenuity Pathway analysis was applied to identify the most significant pathways with differentially methylated positions (DMPs). Secondary analysis of the identified loci included linear correlations between methylation and the subjectively rated scales of sleep, depression and sleep microarchitecture. Results: Due to small sample size, we found no genome-wide significant differences in methylation between cases and controls. However, pathway analysis identified the synaptic long-term depression (LTD) canonical pathway (p = 0.00045) when the best 500 DMPs from the original case-control design were included. A flattened dissipation of slow wave sleep, tiredness and depression severity values correlated with five of 10 sites from the LTD pathway (IGF1R, PLAG16, PLA2R1, PPP2C5 and ERK12) in the secondary analysis when the case-control status was controlled for. Conclusion: Among adolescents, depressive disorder with sleep symptoms is associated with a distinctive epigenetic pattern of DNA methylation in blood leukocytes. The enrichment of DMPs on genes related to synaptic LTD emphasizes the role of sleep in synaptic plasticity and the widespread physiological consequences of disturbed sleep. (C) 2019 Elsevier B.V. All rights reserved.
  • Brownlie, Demi; Scharenberg, Marlena; Mold, Jeff E.; Hard, Joanna; Kekäläinen, Eliisa; Buggert, Marcus; Nguyen, Son; Wilson, Jennifer N.; Al-Ameri, Mamdoh; Ljunggren, Hans-Gustaf; Marquardt, Nicole; Michaelsson, Jakob (2021)
    Human adaptive-like "memory" CD56(dim)CD16(+) natural killer (NK) cells in peripheral blood from cytomegalovirus-seropositive individuals have been extensively investigated in recent years and are currently explored as a treatment strategy for hematological cancers. However, treatment of solid tumors remains limited due to insufficient NK cell tumor infiltration, and it is unknown whether large expansions of adaptive-like NK cells that are equipped for tissue residency and tumor homing exist in peripheral tissues. Here, we show that human lung and blood contains adaptive-like CD56(bright)CD16(-) NK cells with hallmarks of tissue residency, including expression of CD49a. Expansions of adaptive-like lung tissue-resident NK (trNK) cells were found to be present independently of adaptive-like CD56(dim)CD16(+) NK cells and to be hyperresponsive toward target cells. Together, our data demonstrate that phenotypically, functionally, and developmentally distinct subsets of adaptive-like NK cells exist in human lung and blood. Given their tissue-related character and hyperresponsiveness, human lung adaptive-like trNK cells might represent a suitable alternative for therapies targeting solid tumors.
  • Olkkonen, Maria; Aguirre, Geoffrey K.; Epstein, Russell A. (2017)
    Neural responses to stimuli are often attenuated by repeated presentation. When observed in blood oxygen level-dependent signals, this attenuation is known as fMRI adaptation (fMRIa) or fMRI repetition suppression. According to a prominent account, fMRIa reflects the fulfillment of perceptual expectations during recognition of repeated items (Summerfield, Trittschuh, Monti, Mesulam, & Egner, 2008). Supporting this idea, expectation has been shown to modulate fMRIa under some circumstances; however, it is not currently known whether expectation similarly modulates recognition performance. To address this lacuna, we measured behavioral and fMRI responses to faces while varying the extent to which each stimulus was informative about its successor. Behavioral priming was greater when repetitions were more likely, suggesting that recognition was facilitated by the expectation than an item would repeat. Notably, this effect was only observed when stimuli were drawn from a broad set of faces including many ethnicities and both genders, but not when stimuli were drawn from a narrower face set, thus making repetitions less informative. Moreover, expectation did not modulate fMRIa in face-selective cortex, contrary to previous studies, although an exploratory analysis indicated that it did so in a medial frontal region. These results support the idea that expectation modulates recognition efficiency, but insofar as behavioral effects of expectation were not accompanied by fMRI effects in visual cortex, they suggest that fMRIa cannot be entirely explained in terms of fulfilled expectations.
  • PIPARI Study Grp; Lind, Annika; Haataja, Leena; Laasonen, Marja; Saunavaara, Virva; Railo, Henry; Lehtonen, Tuomo; Vorobyev, Victor; Uusitalo, Karoliina; Lahti, Katri; Parkkola, Riitta (2021)
    Objectives: Impairments in visual perception are among the most common developmental difficulties related to being born prematurely, and they are often accompanied by problems in other developmental domains. Neural activation in participants born prematurely and full-term during tasks that assess several areas of visual perception has not been studied. To better understand the neural substrates of the visual perceptual impairments, we compared behavioral performance and brain activations during visual perception tasks in adolescents born very preterm (birth weight <= 1500 g or gestational age <32 weeks) and full-term. Methods: Tasks assessing visual closure, discrimination of a deviating figure, and discrimination of figure and ground from the Motor-Free Visual Perception Test, Third Edition were performed by participants born very preterm (n = 37) and full-term (n = 34) at 12 years of age during functional magnetic resonance imaging. Results: Behavioral performance in the visual perception tasks did not differ between the groups. However, during the visual closure task, brain activation was significantly stronger in the group born very preterm in a number of areas including the frontal, anterior cingulate, temporal, and posterior medial parietal/cingulate cortices, as well as in parts of the cerebellum, thalamus, and caudate nucleus. Conclusions: Differing activations during the visual closure task potentially reflect a compensatory neural process related to premature birth or lesser neural efficiency or may be a result of the use of compensatory behavioral strategies in the study group born very preterm.
  • Kaasinen, Eevi; Kuismin, Outi; Rajamäki, Kristiina; Ristolainen, Heikki; Aavikko, Mervi; Kondelin, Johanna; Saarinen, Silva; Berta, Davide G.; Katainen, Riku; Hirvonen, Elina A. M.; Karhu, Auli; Taira, Aurora; Tanskanen, Tomas; Alkodsi, Amjad; Taipale, Minna; Morgunova, Ekaterina; Franssila, Kaarle; Lehtonen, Rainer; Mäkinen, Markus; Aittomäki, Kristiina; Palotie, Aarno; Kurki, Mitja; Pietiläinen, Olli; Hilpert, Morgane; Saarentaus, Elmo; Niinimäki, Jaakko; Junttila, Juhani; Kaikkonen, Kari; Vahteristo, Pia; Skoda, Radek C.; Seppänen, Mikko R. J.; Eklund, Kari K.; Taipale, Jussi; Kilpivaara, Outi; Aaltonen, Lauri A. (2019)
    Clonal hematopoiesis driven by somatic heterozygous TET2 loss is linked to malignant degeneration via consequent aberrant DNA methylation, and possibly to cardiovascular disease via increased cytokine and chemokine expression as reported in mice. Here, we discover a germline TET2 mutation in a lymphoma family. We observe neither unusual predisposition to atherosclerosis nor abnormal pro-inflammatory cytokine or chemokine expression. The latter finding is confirmed in cells from three additional unrelated TET2 germline mutation carriers. The TET2 defect elevates blood DNA methylation levels, especially at active enhancers and cell-type specific regulatory regions with binding sequences of master transcription factors involved in hematopoiesis. The regions display reduced methylation relative to all open chromatin regions in four DNMT3A germline mutation carriers, potentially due to TET2-mediated oxidation. Our findings provide insight into the interplay between epigenetic modulators and transcription factor activity in hematological neoplasia, but do not confirm the putative role of TET2 in atherosclerosis.
  • Komulainen, Emilia; Varidaki, Artemis; Kulesskaya, Natalia; Mohammad, Hasan; Sourander, Christel; Rauvala, Heikki; Coffey, Eleanor T. (2020)
    The protein kinase JNK1 exhibits high activity in the developing brain, where it regulates dendrite morphology through the phosphorylation of cytoskeletal regulatory proteins. JNK1 also phosphorylates dendritic spine proteins, and Jnk1-/- mice display a long-term depression deficit. Whether JNK1 or other JNKs regulate spine morphology is thus of interest. Here, we characterize dendritic spine morphology in hippocampus of mice lacking Jnk1-/- using Lucifer yellow labelling. We find that mushroom spines decrease and thin spines increase in apical dendrites of CA3 pyramidal neurons with no spine changes in basal dendrites or in CA1. Consistent with this spine deficit, Jnk1-/- mice display impaired acquisition learning in the Morris water maze. In hippocampal cultures, we show that cytosolic but not nuclear JNK, regulates spine morphology and expression of phosphomimicry variants of JNK substrates doublecortin (DCX) or myristoylated alanine-rich C kinase substrate-like protein-1 (MARCKSL1), rescue mushroom, thin, and stubby spines differentially. These data suggest that physiologically active JNK controls the equilibrium between mushroom, thin, and stubby spines via phosphorylation of distinct substrates.
  • Aitta-aho, Teemu; Möykkynen, Tommi Petteri; Panhelainen, Anne E.; Vekovischeva, Olga Yu; Bäckström, Pia; Korpi, Esa R. (2012)