Browsing by Subject "memory"

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  • Witzel, Christoph; Olkkonen, Maria; Gegenfurtner, Karl R. (2018)
    According to the memory colour effect, the colour of a colour-diagnostic object is not perceived independently of the object itself. Instead, it has been shown through an achromatic adjustment method that colour-diagnostic objects still appear slightly in their typical colour, even when they are colourimetrically grey. Bayesian models provide a promising approach to capture the effect of prior knowledge on colour perception and to link these effects to more general effects of cue integration. Here, we model memory colour effects using prior knowledge about typical colours as priors for the grey adjustments in a Bayesian model. This simple model does not involve any fitting of free parameters. The Bayesian model roughly captured the magnitude of the measured memory colour effect for photographs of objects. To some extent, the model predicted observed differences in memory colour effects across objects. The model could not account for the differences in memory colour effects across different levels of realism in the object images. The Bayesian model provides a particularly simple account of memory colour effects, capturing some of the multiple sources of variation of these effects.
  • Leminen, Miika M.; Virkkala, Jussi; Saure, Emma; Paajanen, Teemu; Zee, Phyllis C.; Santostasi, Giovanni; Hublin, Christer; Müller, Kiti; Porkka-Heiskanen, Tarja; Huotilainen, Minna; Paunio, Tiina (2017)
    Introduction: Slow-wave sleep (SWS) slow waves and sleep spindle activity have been shown to be crucial for memory consolidation. Recently, memory consolidation has been causally facilitated in human participants via auditory stimuli phase-locked to SWS slow waves. Aims: Here, we aimed to develop a new acoustic stimulus protocol to facilitate learning and to validate it using different memory tasks. Most importantly, the stimulation setup was automated to be applicable for ambulatory home use. Methods: Fifteen healthy participants slept 3 nights in the laboratory. Learning was tested with 4 memory tasks (word pairs, serial finger tapping, picture recognition, and face-name association). Additional questionnaires addressed subjective sleep quality and overnight changes in mood. During the stimulus night, auditory stimuli were adjusted and targeted by an unsupervised algorithm to be phase-locked to the negative peak of slow waves in SWS. During the control night no sounds were presented. Results: Results showed that the sound stimulation increased both slow wave (p =.002) and sleep spindle activity (p Conclusions: We showed that the memory effect of the SWS-targeted individually triggered single-sound stimulation is specific to verbal associative memory. Moreover, the ambulatory and automated sound stimulus setup was promising and allows for a broad range of potential follow-up studies in the future.
  • 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.
  • Kataja, Meeri (Helsingin yliopisto, 2020)
    Copper mining has characterized the Keweenaw Peninsula, in the Upper Peninsula of Michigan, from the 1840s. The industry that lasted in the region over 100 years has been profoundly studied, but the industrial heritage has received less attention. This study is interested in the memory of mining and in the future prospects of locals right after the closure of the mines in 1969. This study is data-driven, using the interviews conducted within the Finnish Folklore and Social Change in the Great Lakes Mining Region Oral History Project by the Finlandia University in 1973-1978. The method is thematic analysis, which is used to identify, analyze and report themes related to talk on the mines, mining, the 1913 Strike, and the future. Two main themes are negative and positive talk. Within negative talk, three sub-themes are identified: insecurity, disappointment and loss. There is more negative talk within the data set, especially because of the 1913 Strike and the Italian Hall Disaster, which were still commonly remembered. In addition, insecurity is present with topics like working conditions, copper mining operations and workers’ organization. The theme of disappointment is most clear in parts where the interviewees are talking about the economic heritage of mining and strikes that were organized after 1913 too. Loss is felt with the dying industry itself, with environmental heritage, but also when discussing the many men who died in the mines. The sub-themes of positive talk are paternalism, comfort and communality. Paternalism is mostly seen positively: the mining companies took care of the people and the communities. Keweenaw was a single-industry area and the interviewees found comfort in having the mines operating, as this was all they had. The theme of communality includes talk on achievements outside the mining shafts. Interestingly, the region was able to maintain a stable, yet smaller population. Education in particular became important, and many interviewees saw hope in the future even without the mines. The themes within future talk respond well with the themes identified within the remembrance of mining. The history of mining in the Copper Country has largely followed the grand narrative of mining sites. This study focuses on what happens after mining activities come to an end, which is always the case with boom-and-burst industries. It brings to the forefront the locals that have been recognized as important actors in mining operations. In a broad meaning, industrial heritage can comprise the experiences, beliefs and attitudes of locals. In this case, the regionality of industrialization, modernity and de-industrialization is clear, and it can be taken as an example of the industrial heritage of mining
  • Nikolakaros, Georgios; Kurki, Timo; Paju, Janina; Papageorgiou, Sokratis G.; Vataja, Risto; Ilonen, Tuula (2018)
    Background : Non-alcoholic Wernicke's encephalopathy and Korsakoff syndrome are greatly underdiagnosed. There are very few reported cases of neuropsychologically documented non-alcoholic Korsakoff syndrome, and diffusion tensor imaging (DTI) data are scarce. Methods : We report clinical characteristics and neuropsychological as well as radiological findings from three psychiatric patients (one woman and two men) with a history of probable undiagnosed non-alcoholic Wernicke's encephalopathy and subsequent chronic memory problems. Results : All patients had abnormal neuropsychological test results, predominantly in memory. Thus, the neuropsychological findings were compatible with Korsakoff syndrome. However, the neuropsychological findings were not uniform. The impairment of delayed verbal memory of the first patient was evident only when the results of the memory tests were compared to her general cognitive level. In addition, the logical memory test and the verbal working memory test were abnormal, but the word list memory test was normal. The second patient had impaired attention and psychomotor speed in addition to impaired memory. In the third patient, the word list memory test was abnormal, but the logical memory test was normal. All patients had intrusions in the neuropsychological examination. Executive functions were preserved, except for planning and foresight, which were impaired in two patients. Conventional MRI examination was normal. DTI showed reduced fractional anisotropy values in the uncinate fasciculus in two patients, and in the corpus callosum and in the subgenual cingulum in one patient. Conclusions: Non-alcoholic Korsakoff syndrome can have diverse neuropsychological findings. This may partly explain its marked underdiagnosis. Therefore, a strong index of suspicion is needed. The presence of intrusions in the neuropsychological examination supports the diagnosis. Damage in frontotemporal white matter tracts, particularly in the uncinate fasciculus, may be a feature of non-alcoholic Korsakoff syndrome in psychiatric patients.
  • Tervaniemi, Mari; Huotilainen, Minna; Brattico, Elvira (2014)
  • Musanovic, Alisa (Helsingin yliopisto, 2021)
    This thesis concerns the Polish institution of the dom kultury (house of culture). A dom kultury is an arts centre housing activity ranging from music clubs to film screenings. Under Poland’s state socialist regime, it was envisioned as a space for the implementation of socialist ideals, although such goals were not always realised in practice. Since the end of state socialism, houses of culture have been less defined by such programmatic socialising content; nonetheless they continue to occupy a key part in Poland’s cultural landscape. This thesis explores local people’s memories and perceptions of the institution, tracing the different frameworks people use to make sense of the world around them. It also uses the theoretical frameworks of culture, temporality and postsocialism to explore people’s opinions. The study utilises an oral history methodology, with the source material consisting of ten interviews conducted with inhabitants of one town in Poland, Chodzież. The research builds on the growing interest in narrations of the everyday rather than trauma in the oral history of ex-socialist countries. A thematic analysis of the material was conducted according to the research focus of ideal roles and lived experiences of the house of culture. Remote methods had to be adopted due to the ongoing pandemic, which impacted on the data collection process by slowing down participant recruitment, while also enabling greater flexibility in the research process. The first main finding of the study pertains to the role played by the house of culture over time. While the dispersion of cultural activity since socialism means that it no longer provides the novelty that it once did, the house of culture plays a growing role in the community in accommodating local organisations’ activity. Secondly, the study found that while reference to socialism has its place in people’s narrations of the past, it is not necessarily the dominant framework, with reminiscences about individual life biographies intersecting with macro-level periodisations. Finally, the importance of the local community that houses of culture are situated in was underscored in participant’s narrations, surfacing in the themes of cultural loyalty and rivalry. The study supports the findings in previous studies of houses of culture concerning the normative ideal of culture. Discussions surrounding cultural authenticity defined perceptions about degrees to which culture is performed ‘correctly’, whether it concerns the institution’s role as provider or people’s role as consumers (and co-creators). Even for those who engage with the institution sporadically, it remains an important part of the Polish cultural landscape, providing locals with access to artistic culture and beyond. This underscores the main theme that runs throughout the findings, concerning the interplay between importance for the individual and the collective.
  • Järvinen, Ilkka (Helsingfors universitet, 2017)
    Both prenatal hyperglycaemia (caused by maternal diabetes mellitus) and neonatal hypoglycaemia pose a risk to the neurocognitive development of the child: Maternal diabetes mellitus in pregnancy has been reported to be associated with impairments in memory functions of the offspring up to adolescence. Also, an association has been reported between neonatal hypoglycaemia and neurodevelopmental impairments in childhood and adolescence. However, to our knowledge, the association of prenatal hyperglycaemia with memory impairments has not previously been studied in adulthood. As for the possible association of neonatal hypoglycaemia with memory impairments, it has not, to our knowledge, been studied at any age. Furthermore, the separate and combined sequelae of the two risk factors are yet to be directly compared. We hypothesized that the two risk factors, separately and combined, would still in middle age be associated with subtle memory impairments. We assessed memory functions in a follow-up study of a cohort born during 1971–1974 and prospectively studied from birth. The sample included participants exposed to prenatal hyperglycaemia (n = 22), neonatal hypoglycaemia (n = 14), or both (n = 7). It also included controls with no early risks (n = 40). We assessed the participants' memory functions comprehensively, including working memory and immediate and delayed recall of both verbal and visual material. We found an interaction of early risk with the type of digit span task, a measure of working memory: The differences between span task scores varied between the groups. However, no pairwise between-group differences were significant. Thus, the interaction was not specific to any particular groups and likely to be clinically irrelevant. The interaction was non-significant when gestational age and birth weight were controlled for. The early risks were unassociated with scores on other memory tasks. Against our hypotheses, our results suggest that prenatal hyperglycaemia, neonatal hypoglycaemia and their combination are relatively benign disorders, especially when not accompanied by other perinatal complications: The association of prenatal hyperglycaemia with neurocognitive impairments appears to be attenuated in adulthood, and neonatal hypoglycaemia appears to have few long-term sequelae.
  • Valtonen, Jussi; Gregory, Emma; Landau, Barbara; McCloskey, Michael (2014)
  • Olkkonen, Maria; Saarela, Toni P.; Allred, Sarah R. (2016)
    A key challenge for the visual system is to extract constant object properties from incoming sensory information. This information is ambiguous because the same sensory signal can arise from many combinations of object properties and viewing conditions and noisy because of the variability in sensory encoding. The competing accounts for perceptual constancy of surface lightness fall into two classes of model: One derives lightness estimates from border contrasts, and another explicitly infers surface reflectance. To test these accounts, we combined a novel psychophysical task with probabilistic implementations of both models. Observers compared the lightness of two stimuli under a memory demand (a delay between the stimuli), a context change (different surround luminance), or both. Memory biased perceived lightness toward the mean of the whole stimulus ensemble. Context change caused the classical simultaneous lightness contrast effect, in which a target appears lighter against a dark surround and darker against a light surround. These effects were not independent: Combined memory load and context change elicited a bias smaller than predicted assuming an independent combination of biases. Both models explain the memory bias as an effect of prior expectations on perception. Both models also produce a context effect, but only the reflectance model correctly describes the magnitude. The reflectance model, finally, captures the memory-context interaction better than the contrast model, both qualitatively and quantitatively. We conclude that (a) lightness perception is more consistent with reflectance inference than contrast coding and (b) adding a memory demand to a perceptual task both renders it more ecologically valid and helps adjudicate between competing models.
  • Lesnikova, Angelina; Casarotto, Plinio; Moliner, Rafael; Fred, Senem Merve; Biojone, Caroline; Castren, Eero (2021)
    Perineuronal nets (PNNs) have an important physiological role in the retention of learning by restricting cognitive flexibility. Their deposition peaks after developmental periods of intensive learning, usually in late childhood, and they help in long-term preservation of newly acquired skills and information. Modulation of PNN function by various techniques enhances plasticity and regulates the retention of memories, which may be beneficial when memory persistence entails negative symptoms such as post-traumatic stress disorder (PTSD). In this study, we investigated the role of PTP sigma [receptor-type tyrosine-protein phosphatase S, a phosphatase that is activated by binding of chondroitin sulfate proteoglycans (CSPGs) from PNNs] in retention of memories using Novel Object Recognition and Fear Conditioning models. We observed that mice haploinsufficient for PTPRS gene (PTP sigma(+/-)), although having improved short-term object recognition memory, display impaired long-term memory in both Novel Object Recognition and Fear Conditioning paradigm, as compared to WT littermates. However, PTP sigma(+/-) mice did not show any differences in behavioral tests that do not heavily rely on cognitive flexibility, such as Elevated Plus Maze, Open Field, Marble Burying, and Forced Swimming Test. Since PTP sigma has been shown to interact with and dephosphorylate TRKB, we investigated activation of this receptor and its downstream pathways in limbic areas known to be associated with memory. We found that phosphorylation of TRKB and PLC gamma are increased in the hippocampus, prefrontal cortex, and amygdaloid complex of PTP sigma(+/-) mice, but other TRKB-mediated signaling pathways are not affected. Our data suggest that PTP sigma downregulation promotes TRKB phosphorylation in different brain areas, improves short-term memory performance but disrupts long-term memory retention in the tested animal models. Inhibition of PTP sigma or disruption of PNN-PTP sigma-TRKB complex might be a potential target for disorders where negative modulation of the acquired memories can be beneficial.
  • Lindberg, Susanna (2019)
    Bernard Stiegler is known as a leading philosopher of technics. He has developed an original interpretation of technics as an externalized epiphylogenetic memory that (1) remembers in the place of the human being, who appears therefore as a forgetful being and (2) is collective and constitutes a technological community, that is different from any ethnical-political community. Stiegler has also examined the social and political consequences of contemporary technology. Technics are not neutral. Contemporary digital technologies claim to inform but more fundamentally they produce pulsions in a way that is destructive to psychic and collective individuation and leads to a generalized proletarianization, where the problem is not biopower or capitalism but lack of attention and desire. Can the digital world become a new public space? Stiegler is quite pessimistic, but in principle, to some extent, it is possible to seize and convert ‘the means of memory production.’ Stiegler's insights are invaluable in the task of evaluating new learning technologies, because he analyzes political community from the double point of view of technology, and of the care of younger generations. In this article, I present Stiegler's philosophical theory and show how it can be applied to education and digital learning environments.
  • Hakonen, Maria; May, Patrick J. C.; Jaaskelainen, Iiro P.; Jokinen, Emma; Sams, Mikko; Tiitinen, Hannu (2017)
    Introduction: We examined which brain areas are involved in the comprehension of acoustically distorted speech using an experimental paradigm where the same distorted sentence can be perceived at different levels of intelligibility. This change in intelligibility occurs via a single intervening presentation of the intact version of the sentence, and the effect lasts at least on the order of minutes. Since the acoustic structure of the distorted stimulus is kept fixed and only intelligibility is varied, this allows one to study brain activity related to speech comprehension specifically. Methods: In a functional magnetic resonance imaging (fMRI) experiment, a stimulus set contained a block of six distorted sentences. This was followed by the intact counterparts of the sentences, after which the sentences were presented in distorted form again. A total of 18 such sets were presented to 20 human subjects. Results: The blood oxygenation level dependent (BOLD)-responses elicited by the distorted sentences which came after the disambiguating, intact sentences were contrasted with the responses to the sentences presented before disambiguation. This revealed increased activity in the bilateral frontal pole, the dorsal anterior cingulate/paracingulate cortex, and the right frontal operculum. Decreased BOLD responses were observed in the posterior insula, Heschl's gyrus, and the posterior superior temporal sulcus. Conclusions: The brain areas that showed BOLD-enhancement for increased sentence comprehension have been associated with executive functions and with the mapping of incoming sensory information to representations stored in episodic memory. Thus, the comprehension of acoustically distorted speech may be associated with the engagement of memory-related subsystems. Further, activity in the primary auditory cortex was modulated by prior experience, possibly in a predictive coding framework. Our results suggest that memory biases the perception of ambiguous sensory information toward interpretations that have the highest probability to be correct based on previous experience.
  • Coskun, Tugce (Helsingin yliopisto, 2018)
    Memory has become one of the most vibrant areas of research within the field of media studies. Due to the technological advancements of the past two decades, our media consumption has developed globally. Collective memory and media memory scholars argue that our memories are increasingly influenced by media as well as our surrounding social groups. This study focuses on the media memories of the Lebanese diaspora in North America concerning two significant Lebanese political events. The main research questions are: What do the Lebanese living in North America remember about the two events? What is the role of media in the way they remember the events? This thesis also explores two sub-research questions: How do the participants’ social groups influence the way the individuals remember the events? How does their media consumption affect their memories? The data for this study was collected through semi-structured interviews with participants from two different age groups in the Lebanese diaspora in North America. The data was analyzed with thematic analysis, and the findings showed that participants remembered very specific details about the events from what they remembered seeing on the TV news. There were some noticeable differences between the memories of the two age groups. This could be contributed to the fact that for the younger participants, their families and other social groups affected their memories of the events. This pointed in the direction that their memories were influenced by the traumatic significance of these events for their social groups. There were types of memories evident throughout the analysis, which were categorized under the concepts of postmemory and flashbulb memories. Essentially, these memories also had influences rooted in social groups and/or media sources for the participants.
  • Uusihakala, Katja Marikka (2019)
    Focusing on Prime Minister Gordon Brown’s apology to British child migrants in 2010, this article proposes that public apology, as a moral and political act, is a compelling site for examining attempts to redefine and redress previously silenced pasts. Postwar child migration has been something of a silenced chapter in British history. In my research I examine one such child migration scheme, namely a project which sent select British children (aged 4 to 13) to colonial Southern Rhodesia—today’s Zimbabwe—between 1946 and 1962. Through this case, I discuss two intertwined aspects of the transformative intentions of apologizing. First, the apology aims at amending the relationship between the apologizer and the victims and at remodeling the recipients’ political subjectivities. Second, the apology discloses distinct, but contradictory, understandings about the relationship between past, present, and future. It emphasizes the continuous effects the past has in the present, but simultaneously purports to create a temporal break with the past, marked by a moral transformation of the state. However, although the apology aspires and has potential to give voice to those previously silenced and to re-articulate a more legitimate version of the past, its framing eliminates the broader historical context of the Empire. Thus, while partially overcoming silences, the article suggests, the apology also reproduces and reinforces others.
  • Räsänen, Matti; Merbold, Lutz; Vakkari, Ville; Aurela, Mika; Laakso, Lauri; Beukes, Johan P.; Zyl, Pieter G. Van; Josipovic, Miroslav; Feig, Gregor; Pellikka, Petri; Rinne, Janne; Katul, Gabriel (2020)
    The main source of soil moisture variability in savanna ecosystems is pulsed rainfall. Rainfall pulsing impacts water-stress durations, soil moisture switching between wet-to-dry and dry-to-wet states, and soil moisture spectra as well as derived measures from it such as soil moisture memory. Rainfall pulsing is also responsible for rapid changes in grassland leaf area and concomitant changes in evapotranspirational (ET) losses, which then impact soil moisture variability. With the use of a hierarchy of models and soil moisture measurements, temporal variability in root-zone soil moisture and water-stress periods are analysed at four African sites ranging from grass to miombo savannas. The normalized difference vegetation index (NDVI) and potential ET (PET)-adjusted ET model predict memory timescale and dry persistence in agreement with measurements. The model comparisons demonstrate that dry persistence and mean annual dry periods must account for seasonal and interannual changes in maximum ET represented by NDVI and to a lesser extent PET. Interestingly, the precipitation intensity and soil moisture memory were linearly related across three savannas with ET/infiltration similar to 1.0. This relation and the variability of length and timing of dry periods are also discussed.
  • Reyes-Garcia, Victoria; Pyhälä, Aili; Diaz-Reviriego, Isabel; Duda, Romain; Fernandez-Llamazares Onrubia, Alvaro; Gallois, Sandrine; Gueze, Maximilien; Napitupulu, Lucentezza (2016)
    Researchers have analysed whether school and local knowledge complement or substitute each other, but have paid less attention to whether those two learning models use different cognitive strategies. In this study, we use data collected among three contemporary hunter-gatherer societies with relatively low levels of exposure to schooling yet with high levels of local ecological knowledge to test the association between i) schooling and ii) local ecological knowledge and verbal working memory. Participants include 94 people (24 Baka, 25 Punan, and 45 Tsimane') from whom we collected information on 1) schooling and school related skills (i.e., literacy and numeracy), 2) local knowledge and skills related to hunting and medicinal plants, and 3) working memory. To assess working memory, we applied a multi-trial free recall using words relevant to each cultural setting. People with and without schooling have similar levels of accurate and inaccurate recall, although they differ in their strategies to organize recall: people with schooling have higher results for serial clustering, suggesting better learning with repetition, whereas people without schooling have higher results for semantic clustering, suggesting they organize recall around semantically meaningful categories. Individual levels of local ecological knowledge are not related to accurate recall or organization recall, arguably due to overall high levels of local ecological knowledge. While schooling seems to favour some organization strategies this might come at the expense of some other organization strategies.