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  • 1. Aaltonen, Olli
    et al.
    Hellström, Åke
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Peltola, Maija S.
    Savela, Janne
    Tamminen, Henna
    Lehtola, Heidi
    Brain responses reveal hardwired detection of native-language rule violations2008In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 444, no 1, 56-59 p.Article in journal (Refereed)
    Abstract [en]

    Mismatch negativity (MMN) is a neural correlate of the preattentive detection of any change in the acoustic characteristics of sounds. Here we provide evidence that violations of a purely phonological constraint in a listener's native language can also elicit the brain's automatic change-detection response. The MMN differed between Finnish and Estonian listeners, conditions being equal except for the native language of the listeners. We used two experimental conditions: synthetic vowels in isolation and the same vowels embedded in a pseudo-word context. MMN responses to isolated vowels were similar for Finns and Estonians, while the same vowels in a pseudoword context elicited different MMN patterns depending on the listener's mother tongue.

  • 2.
    Adlerz, Linda
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Soomets, Ursel
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology. University of Tartu, Estonia.
    Holmlund, Linda
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Virland, Saade
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Iverfeldt, Kerstin
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Down-regulation of amyloid precursor protein by peptide nucleic acid oligomer in cultured rat primary neurons and astrocytes2003In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 336, no 1, 55-59 p.Article in journal (Refereed)
    Abstract [en]

    The amyloid precursor protein (APP) and its proteolytic cleavage products, the amyloid P peptides, have been implicated as a cause of Alzheimer's disease. Peptide nucleic acids (PNA), the DNA mimics, have been shown to block the expression of specific proteins at both transcriptional and translational levels. Generally, the cellular uptake of PNA is low. However, recent studies have indicated that the effect of unmodified antisense PNA uptake is more pronounced in nervous tissue. In this study we have shown that biotinylated PNA directed to the initiator codon region of the APP mRNA (-4 - +11) was taken up into the cytoplasm of primary rat cerebellar granule cells and cortical astrocytes, using fluorescence and confocal microscopy studies. Uptake of PNA was faster in neurons than in astrocytes. Western blotting analysis showed that APP was strongly down-regulated in both neurons and astrocytes. Thus, unmodified PNA can be used for studies on the function of APP in neurons and astrocytes.

  • 3. Besga, A.
    et al.
    Cedazo-Minguez, A.
    Kåreholt, I.
    Stockholm University, Faculty of Social Sciences, Aging Research Center (ARC), (together with KI).
    Solomon, A.
    Stockholm University, Faculty of Social Sciences, Aging Research Center (ARC), (together with KI).
    Björkhem, I.
    Winblad, B.
    Leoni, V.
    Hooshmand, B.
    Stockholm University, Faculty of Social Sciences, Aging Research Center (ARC), (together with KI).
    Spulber, G.
    Gonzalez-Pinto, A.
    Kivipelto, M.
    Stockholm University, Faculty of Social Sciences, Aging Research Center (ARC), (together with KI).
    Wahlund, L. O.
    Differences in brain cholesterol metabolism and insulin in two subgroups of patients with different CSF biomarkers but similar white matter lesions suggest different pathogenic mechanisms2012In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 510, no 2, 121-126 p.Article in journal (Refereed)
    Abstract [en]

    Investigate possible associations of white matter hyperintensities (WMHs) with the metabolism of cholesterol and insulin in two subgroups of patients with memory complaints and different CSF A beta 42 and CSF tau levels. 59 patients from the memory clinic at Karolinska Hospital were included. Degree of WMHs was rated using the ARWMC scale and the following biomarkers were measured in CSF and plasma: insulin, cholesterol, lanosterol, lathosterol, and oxidized cholesterol metabolites. The WMHs in CSF control-like group correlated with increased brain cholesterol synthesis and reduced efflux of oxysterols and insulin in CSF. In the CSF AD-like group, the WMHs correlated with increased peripheral cholesterol metabolism. Despite having similar appearance on FLAIR images, the pathogenic mechanisms of WMHS are likely to be different in the two groups investigated.

  • 4.
    Bruzzo, Angela
    et al.
    Department of Psychology, University of Bologna.
    Borghi, Anna M.
    Department of Psychology, University of Bologna.
    Ghirlanda, Stefano
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Hand–object interaction in perspective2008In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 441, 61-65 p.Article in journal (Refereed)
  • 5. Eriksson, Johan
    et al.
    Kalpouzos, Grégoria
    Stockholm University, Faculty of Social Sciences, Aging Research Center (ARC), (together with KI).
    Nyberg, Lars
    Rewiring the brain with repeated retrieval: a parametric fMRI study of the testing effect2011In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 505, no 1, 36-40 p.Article in journal (Refereed)
    Abstract [en]

    The "testing effect" refers to the beneficial effects on memory performance from being tested, a phenomenon of potentially substantial implications in educational settings. While the effect itself is firmly established in previous research, little is known of related brain changes. Here we used fMRI and a parametric design to show that repeated successful retrieval during a memory acquisition phase leads to higher brain activity in the anterior cingulate cortex (ACC) at a subsequent test phase. The extent of ACC activity increase correlated across individuals with memory performance 5 months later. In relation to recent research that associates the ACC with memory consolidation processes, the present results suggest that the testing effect may operate at the systems level by enhancing consolidation of memory representations.

  • 6.
    Forsby, A
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Walum, E
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Polygodial induces inositol phosphate turnover in human neuroblastoma SH-SY5Y cells.1996In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 217, no 1, 50-4 p.Article in journal (Refereed)
    Abstract [en]

    The pungent sesquiterpenoid unsaturated dialdehydes polygodial and isovelleral, have previously been shown to increase the intracellular free calcium concentration [Ca2+]i in human neuroblastoma SH-SY5Y cells, partly by a release from intracellular Ca2+ stores, whereas the non-pungent compound epipolygodial, had no effect on the [Ca2+]i. In this study, we investigated the effect of isovelleral, polygodial and epipolygodial on inositol phosphate (IP) formation on the assumption that there might be a correlation between the release of intracellular Ca2+ and pungency of the compounds. It was found that polygodial induced IP mobilization in a concentration dependent way, whereas isovelleral had no effect on the IP formation in the SH-SY5Y cells. Phosphoinositide (PPI) turnover was activated by epipolygodial, but only at concentrations 40-fold higher than for polygodial, which emphasizes the importance of the correct stereometry in the dialdehyde configuration for the biological activity of polygodial. The polygodial-induced formation of IP1 was reduced by 71% under extracellular calcium-free conditions, which suggests feedback interactions between the IP formation and the increase in [Ca2+]i to account for a periodic activation of phospholipase C(PLC).

  • 7. Frick, Andreas
    et al.
    Howner, Katarina
    Fischer, Håkan
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Eskildsen, Simon Fristed
    Kristiansson, Marianne
    Furmark, Tomas
    Cortical thickness alterations in social anxiety disorder2013In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 536, 52-55 p.Article in journal (Refereed)
    Abstract [en]

    Social anxiety disorder (SAD) has been associated with aberrant processing of socio-emotional stimuli and failure to adaptively regulate emotion, corroborated by functional neuroimaging studies. However, only a few studies of structural brain abnormalities in SAD have been reported, and among these only one investigated cortical thickness. In the present study we used magnetic resonance imaging (MRI) in conjunction with an automated method to measure cortical thickness in patients with SAD (n=14) and healthy controls (n=12). Results showed significantly increased thickness of the left inferior temporal cortex in SAD patients relative to controls. Within the patient group, a negative association was found between social anxiety symptom severity and thickness of the right rostral anterior cingulate cortex. The observed alterations in brain structure may help explain previous findings of dysfunctional regulation and processing of emotion in SAD.

  • 8.
    Koistinen, Niina A.
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Bacanu, Smaranda
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Iverfeldt, Kerstin
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Phosphorylation of Fe65 amyloid precursor protein-binding protein in response to neuronal differentiation2016In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 613, 54-59 p.Article in journal (Refereed)
    Abstract [en]

    Fe65 is a brain enriched multi domain adaptor protein involved in diverse cellular functions. One of its binding partners is the amyloid-beta (A beta) precursor protein (APP), which after sequential proteolytic processing by secretases gives rise to the Alzheimer's A beta peptide. Fe65 binds to the APP intracellular domain (AICD). Several studies have indicated that Fe65 binding promotes the amyloidogenic processing of APP. It has previously been shown that expression of APP increases concomitantly with a shift of its processing to the non-amyloidogenic pathway during neuronal differentiation. In this study we wanted to investigate the effects of neuronal differentiation on Fe65 expression. We observed that differentiation of SH-SY5Y human neuroblastoma cells induced by retinoic acid (RA), the phorbol ester PMA, or the gamma-secretase inhibitor DAPT resulted in an electrophoretic mobility shift of Fe65. Similar effects were observed in rat PC6.3 cells treated with nerve growth factor. The electrophoretic mobility shift was shown to be due to phosphorylation. Previous studies have shown that Fe65 phosphorylation can prevent the APP-Fe65 interaction. We propose that phosphorylation is a way to modify the functions of Fe65 and to promote the non-amyloidogenic processing of APP during neuronal differentiation.

  • 9. Kompus, Kristiina
    et al.
    Hugdahl, Kenneth
    Ohman, Arne
    Marklund, Petter
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Nyberg, Lars
    Distinct control networks for cognition and emotion in the prefrontal cortex2009In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 467, no 2, 76-80 p.Article in journal (Refereed)
    Abstract [en]

    The activation of dorsolateral prefrontal cortex (dlPFC) has been suggested to reflect the engagement of a control mechanism for top-down biasing of context processing in resource-demanding memory tasks. Here we tested the hypothesis that the dlPFC subserves a similar function also in attention and emotion tasks. 18 healthy young adults were tested in a functional magnetic resonance imaging (fMRI) study where the demands for context processing were manipulated in three different cognitive domains: auditory attention, episodic retrieval, and emotion regulation. We found that the right dlPFC was jointly sensitive to increased cognitive demands in the attention and memory tasks. By contrast, increased demands in the emotion task (reappraisal) were associated with increased activity in ventromedial PFC along with decreased amygdala activity. Our findings of divergent prefrontal control networks for cognitive and emotional control extend previous separations of cognition and emotion in the anterior cingulate cortex.

  • 10.
    Pinho, Catarina Moreira
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Bjork, Behnosh F.
    Alikhani, Nyosha
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Bäckman, Hans G.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Eneqvist, Therese
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Fratiglioni, Laura
    Stockholm University, Faculty of Social Sciences, Aging Research Center (ARC), (together with KI).
    Glaser, Elzbieta
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Graff, Caroline
    Genetic and biochemical studies of SNPs of the mitochondrial A beta-degrading protease, hPreP2010In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 469, no 2, 204-208 p.Article in journal (Refereed)
    Abstract [en]

    Several studies suggest mitochondrial dysfunction as a possible mechanism underlying the development of Alzheimer disease (AD). There is data showing that amyloid-beta (A beta) peptide is present in AD brain mitochondria. The human presequence protease (hPreP) was recently shown to be the major mitochondrial A beta-degrading enzyme. We investigated if there is an increased susceptibility to AD, which can be attributed to genetic variation in the hPreP gene PITRM1 and if the proteolytic efficiency of recombinant hPreP variants is affected. When a total of 673 AD cases and 649 controls were genotyped for 18 single nucleotide polymorphisms (SNPs), no genetic association between any of the SNPs and the risk for AD was found. In contrast, functional analysis of four non-synonymous SNPs in hPreP revealed a decreased activity compared to wild type hPreP. Using A beta, the presequence of ATP synthase F-1 beta subunit and a fluorescent peptide as substrates, the lowest activity was observed for the hPreP(A525D) variant, corresponding to rs1224893, which displayed only 20-30% of wild type activity. Furthermore, the activity of all variants was restored by the addition of Mg2+, suggesting an important role for this metal during proteolysis. In conclusion, our data suggest that genetic variation in the hPreP gene PITRM1 may potentially contribute to mitochondrial dysfunctions.

  • 11. Seo, Han-Seok
    et al.
    Arshamian, Artin
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Schemmer, Kerstin
    Scheer, Ingeborg
    Sander, Thorsten
    Ritter, Guido
    Hummel, Thomas
    Cross-modal integration between odors and abstract symbols2010In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 478, no 3, 175-178 p.Article in journal (Refereed)
    Abstract [en]

    This study aimed to investigate the cross-modal association of an ""abstract symbol,"" designed for representation of an odor, with its corresponding odor. First, to explore the associations of abstract symbols with odors, participants were asked to match 8 odors with 19 different abstract symbols (Experiment 1). Next, we determined whether congruent symbols could modulate olfactory perception and olfactory event-related potentials (ERPs) (Experiment 2). One of two odors (phenylethanol (PEA) or 1-butanol) was presented with one of three conditions (congruent or incongruent symbol, no-symbol), and participants were asked to rate odor intensity and pleasantness during olfactory ERP recordings. Experiment 1 demonstrated that certain abstract symbols could be paired with specific odors. In Experiment 2 congruent symbol enhanced the intensity of PEA compared to no-symbol presentation. In addition, the respective congruent symbol increased the pleasantness of PEA and the unpleasantness of 1-butanol. Finally, compared to the incongruent symbol, the congruent symbol produced significantly higher amplitudes and shorter latencies in the N1 peak of olfactory ERPs. In conclusion, our findings demonstrated that abstract symbols may be associated with specific odors.

  • 12.
    Syrjanen, Elmeri
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Wiens, Stefan
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Gender moderates valence effects on the late positive potential to emotional distracters2013In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 551, 89-93 p.Article in journal (Refereed)
    Abstract [en]

    Attention is captured more strongly by emotional pictures than by neutral pictures. This allocation of attention to emotional pictures is commonly indexed by the late positive potential (LPP). This event-related potential (ERP) is larger for negative and positive pictures than for neutral pictures. However, findings are mixed in regards to valence effects, that is, whether the LPP is larger for negative pictures than for positive pictures (negativity bias) or vice versa (positivity bias). Additionally, previous ERP studies have not explicitly considered a moderating effect of gender. In the present study, positive, negative, and neutral pictures were shown at fixation but were always task-irrelevant. Results showed that LPP amplitudes for the positive and negative distracters were moderated by gender. Men showed a positivity bias on the LPP (i.e., larger amplitudes for positive pictures than for negative pictures). Women did not show a clear valence bias on the LPP, but they showed a negativity bias on picture ratings. These gender differences for the LPP did not habituate, as they were obtained even for pictures that were repeated 20 times. Because previous studies with other measures suggest a positivity bias for men and a negativity bias for women, the present findings extend these studies suggesting that attention allocation for emotional pictures of different valence is similarly moderated by gender.

  • 13.
    Szychowska, Malina
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Perception and psychophysics.
    Eklund, Rasmus
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Perception and psychophysics.
    Nilsson, Mats E.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Perception and psychophysics.
    Wiens, Stefan
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Perception and psychophysics.
    Effects of sound pressure level and visual perceptual load on the auditory mismatch negativity2017In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 640, 37-41 p.Article in journal (Refereed)
    Abstract [en]

    Auditory change detection has been studied extensively with mismatch negativity (MMN), an event-related potential. Because it is unresolved if the duration MMN depends on sound pressure level (SPL), we studied effects of different SPLs (56, 66, and 76 dB) on the duration MMN. Further, previous research suggests that the MMN is reduced by a concurrent visual task. Because a recent behavioral study found that high visual perceptual load strongly reduced detection sensitivity to irrelevant sounds, we studied if the duration MMN is reduced by load, and if this reduction is stronger at low SPLs. Although a duration MMN was observed for all SPLs, the MMN was apparently not moderated strongly by SPL, perceptual load, or their interaction, because all 95% CIs overlapped zero. In a contrast analysis of the MMN (across loads) between the 56-dB and 76-dB groups, evidence (BF = 0.31) favored the null hypothesis that duration MMN is unaffected by a 20-dB increase in SPL. Similarly, evidence (BF = 0.19) favored the null hypothesis that effects of perceptual load on the duration MMN do not change with a 20-dB increase in SPL. However, evidence (BF = 3.12) favored the alternative hypothesis that the effect of perceptual load in the present study resembled the overall effect in a recent meta-analysis. When the present findings were combined with the meta-analysis, the effect of load (low minus high) was −0.43 μV, 95% CI [−0.64, −0.22] suggesting that the duration MMN decreases with load. These findings provide support for a sensitive monitoring system of the auditory environment.

  • 14.
    Wiens, Stefan
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Sand, Anders
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Norberg, Joakim
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Andersson, Per
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Emotional event-related potentials are reduced if negative pictures presented at fixation are unattended2011In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 495, no 3, 178-182 p.Article in journal (Refereed)
    Abstract [en]

    Viewing of emotional pictures elicits two event-related potentials (ERPs) to emotional versus neutral pictures: an early posterior negativity (EPN) and a late positive potential (LPP). Because it is unresolved whether these indexes of emotional processing are reduced to task-irrelevant pictures at fixation, negative and neutral pictures from the International Affective Picture Set (IAPS) were shown at fixation together with 6 letters that surrounded the pictures. In separate tasks, participants were instructed to attend either the pictures or the letters. When the pictures were task relevant, results showed an EPN and LPP. In contrast, when the pictures were task irrelevant, the EPN was eliminated and the LPP reduced. Performance was high in both tasks (hit rates > 87%), but somewhat better when the pictures were relevant. However, analyses showed no relationship between this performance difference and the differences in EPN and LPP between tasks. These results suggest that emotional processing of strong, negative pictures is sensitive to manipulations of attention even if the pictures are shown at fixation.

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