Mousavi-Nasab S.-M.-H.,Shahid Bahonar University of Kerman |
Kormi-Nouri R.,Örebro University |
Nilsson L.-G.,University of Stockholm |
Nilsson L.-G.,Stockholm Brain Institute
British Journal of Psychology | Year: 2014
The present study examined the relationships between different types of social and cognitive activities and different types of episodic and semantic memory. A total of 794 adult men and women from five age cohorts (aged 65-85 at baseline), participating in the longitudinal Betula project on ageing, memory, and health, were included in the study. The participants were studied over 10 years (1995-2005) in three waves. Recognition and recall were used as episodic memory tasks, and knowledge and verbal fluency as semantic memory tasks. The results, after controlling for age, gender, education, and some diseases, including heart disease and hypertension, as covariates, showed unidirectional effects of social activity on episodic memory on all test occasions (β = .10). Also, episodic memory predicted change in cognitive activity for all test waves (β = .21-.22). Findings suggest that social activity can be seen as protective factor against memory decline. It also seems that episodic memory performance is a predictor of cognitive activity in old people. However, the opposite direction does not hold true. © 2013 The British Psychological Society.
Persson N.,University of Stockholm |
Persson N.,Stockholm Brain Institute |
Persson N.,Wayne State University |
Ghisletta P.,University of Geneva |
And 7 more authors.
NeuroImage | Year: 2014
We examined regional changes in brain volume in healthy adults (. N=. 167, age 19-79. years at baseline; N=. 90 at follow-up) over approximately two years. With latent change score models, we evaluated mean change and individual differences in rates of change in 10 anatomically-defined and manually-traced regions of interest (ROIs): lateral prefrontal cortex (LPFC), orbital frontal cortex (OF), prefrontal white matter (PFw), hippocampus (Hc), parahippocampal gyrus (PhG), caudate nucleus (Cd), putamen (Pt), insula (In), cerebellar hemispheres (CbH), and primary visual cortex (VC). Significant mean shrinkage was observed in the Hc, CbH, In, OF, and PhG, and individual differences in change were noted in all regions, except the OF. Pro-inflammatory genetic variants modified shrinkage in PhG and CbH. Carriers of two T alleles of interleukin-1β (. IL-1β C-511T, rs16944) and a T allele of methylenetetrahydrofolate reductase (. MTHFR C677T, rs1801133) polymorphisms showed increased PhG shrinkage. No effects of a pro-inflammatory polymorphism for C-reactive protein (. CRP-286C>A>T, rs3091244) or apolipoprotein (. APOE) ε4 allele were noted. These results replicate the pattern of brain shrinkage observed in previous studies, with a notable exception of the LPFC, thus casting doubt on the unique importance of prefrontal cortex in aging. Larger baseline volumes of CbH and In were associated with increased shrinkage, in conflict with the brain reserve hypothesis. Contrary to previous reports, we observed no significant linear effects of age and hypertension on regional brain shrinkage. Our findings warrant further investigation of the effects of neuroinflammation on structural brain change throughout the lifespan. © 2014 Elsevier Inc.
Klaus A.,National Institute of Mental Health |
Klaus A.,Karolinska Institutet |
Klaus A.,Stockholm Brain Institute |
Yu S.,National Institute of Mental Health |
Plenz D.,National Institute of Mental Health
PLoS ONE | Year: 2011
The size distribution of neuronal avalanches in cortical networks has been reported to follow a power law distribution with exponent close to -1.5, which is a reflection of long-range spatial correlations in spontaneous neuronal activity. However, identifying power law scaling in empirical data can be difficult and sometimes controversial. In the present study, we tested the power law hypothesis for neuronal avalanches by using more stringent statistical analyses. In particular, we performed the following steps: (i) analysis of finite-size scaling to identify scale-free dynamics in neuronal avalanches, (ii) model parameter estimation to determine the specific exponent of the power law, and (iii) comparison of the power law to alternative model distributions. Consistent with critical state dynamics, avalanche size distributions exhibited robust scaling behavior in which the maximum avalanche size was limited only by the spatial extent of sampling ("finite size" effect). This scale-free dynamics suggests the power law as a model for the distribution of avalanche sizes. Using both the Kolmogorov-Smirnov statistic and a maximum likelihood approach, we found the slope to be close to -1.5, which is in line with previous reports. Finally, the power law model for neuronal avalanches was compared to the exponential and to various heavy-tail distributions based on the Kolmogorov-Smirnov distance and by using a log-likelihood ratio test. Both the power law distribution without and with exponential cut-off provided significantly better fits to the cluster size distributions in neuronal avalanches than the exponential, the lognormal and the gamma distribution. In summary, our findings strongly support the power law scaling in neuronal avalanches, providing further evidence for critical state dynamics in superficial layers of cortex.
Petrovic P.,Stockholm Brain Institute |
Kalso E.,University of Helsinki |
Petersson K.M.,Stockholm Brain Institute |
Petersson K.M.,FARO |
And 3 more authors.
Pain | Year: 2010
Behavioral studies have suggested that placebo analgesia is partly mediated by the endogenous opioid system. Expanding on these results we have shown that the opioid-receptor-rich rostral anterior cingulate cortex (rACC) is activated in both placebo and opioid analgesia. However, there are also differences between the two treatments. While opioids have direct pharmacological effects, acting on the descending pain inhibitory system, placebo analgesia depends on neocortical top-down mechanisms. An important difference may be that expectations are met to a lesser extent in placebo treatment as compared with a specific treatment, yielding a larger error signal. As these processes previously have been shown to influence other types of perceptual experiences, we hypothesized that they also may drive placebo analgesia. Imaging studies suggest that lateral orbitofrontal cortex (lObfc) and ventrolateral prefrontal cortex (vlPFC) are involved in processing expectation and error signals. We re-analyzed two independent functional imaging experiments related to placebo analgesia and emotional placebo to probe for a differential processing in these regions during placebo treatment vs. opioid treatment and to test if this activity is associated with the placebo response. In the first dataset lObfc and vlPFC showed an enhanced activation in placebo analgesia vs. opioid analgesia. Furthermore, the rACC activity co-varied with the prefrontal regions in the placebo condition specifically. A similar correlation between rACC and vlPFC was reproduced in another dataset involving emotional placebo and correlated with the degree of the placebo effect. Our results thus support that placebo is different from specific treatment with a prefrontal top-down influence on rACC. © 2010 International Association for the Study of Pain.
Soderqvist S.,Karolinska Institutet |
Soderqvist S.,Stockholm Brain Institute |
Nutley S.B.,Karolinska Institutet |
Nutley S.B.,Stockholm Brain Institute |
And 4 more authors.
Frontiers in Human Neuroscience | Year: 2012
Children with intellectual disabilities show deficits in both reasoning ability and working memory (WM) that impact everyday functioning and academic achievement. In this study we investigated the feasibility of cognitive training for improving WM and non-verbal reasoning (NVR) ability in children with intellectual disability. Participants were randomized to a 5- week adaptive training program (intervention group) or non-adaptive version of the program (active control group). Cognitive assessments were conducted prior to and directly after training, and one year later to examine effects of the training. Improvements during training varied largely and amount of progress during training predicted transfer to WM and comprehension of instructions, with higher training progress being associated with greater transfer improvements. The strongest predictors for training progress were found to be gender, co-morbidity and baseline capacity on verbal WM. In particular, females without an additional diagnosis and with higher baseline performance showed greater progress. No significant effects of training were observed at the one-year follow-up, suggesting that training should be more intense or repeated in order for effects to persist in children with intellectual disabilities. A major finding of this study is that cognitive training is feasible in this clinical sample and can help improve their cognitive performance. However, a minimum cognitive capacity or training ability seems necessary for the training to be beneficial, with some individuals showing little improvement in performance. Future studies of cognitive training should take into consideration how inter-individual differences in training progress influence transfer effects and further investigate how baseline capacities predict training outcome. © 2012 Söderqvist, Bergman nutley, Ottersen, Grill and Klingberg.
Selbing I.,Karolinska Institutet |
Selbing I.,Stockholm Brain Institute |
Lindstrom B.,Karolinska Institutet |
Lindstrom B.,Stockholm Brain Institute |
And 2 more authors.
Cognition | Year: 2014
Learning to avoid danger by observing others can be relatively safe, because it does not incur the potential costs of individual trial and error. However, information gained through social observation might be less reliable than information gained through individual experiences, underscoring the need to apply observational learning critically. In order for observational learning to be adaptive it should be modulated by the skill of the observed person, the demonstrator. To address this issue, we used a probabilistic two-choice task where participants learned to minimize the number of electric shocks through individual learning and by observing a demonstrator performing the same task. By manipulating the demonstrator's skill we varied how useful the observable information was; the demonstrator either learned the task quickly or did not learn it at all (random choices). To investigate the modulatory effect in detail, the task was performed under three conditions of available observable information; no observable information, observation of choices only, and observation of both the choices and their consequences. As predicted, our results showed that observable information can improve performance compared to individual learning, both when the demonstrator is skilled and unskilled; observation of consequences improved performance for both groups while observation of choices only improved performance for the group observing the skilled demonstrator. Reinforcement learning modeling showed that demonstrator skill modulated observational learning from the demonstrator's choices, but not their consequences, by increasing the degree of imitation over time for the group that observed a fast learner. Our results show that humans can adaptively modulate observational learning in response to the usefulness of observable information. © 2014 Elsevier B.V.
Lindstrom B.R.,Karolinska Institutet |
Lindstrom B.R.,Stockholm Brain Institute |
Mattsson-Marn I.B.,Karolinska Institutet |
Golkar A.,Karolinska Institutet |
And 3 more authors.
PLoS ONE | Year: 2013
Cognitive control is needed when mistakes have consequences, especially when such consequences are potentially harmful. However, little is known about how the aversive consequences of deficient control affect behavior. To address this issue, participants performed a two-choice response time task where error commissions were expected to be punished by electric shocks during certain blocks. By manipulating (1) the perceived punishment risk (no, low, high) associated with error commissions, and (2) response conflict (low, high), we showed that motivation to avoid punishment enhanced performance during high response conflict. As a novel index of the processes enabling successful cognitive control under threat, we explored electromyographic activity in the corrugator supercilii (cEMG) muscle of the upper face. The corrugator supercilii is partially controlled by the anterior midcingulate cortex (aMCC) which is sensitive to negative affect, pain and cognitive control. As hypothesized, the cEMG exhibited several key similarities with the core temporal and functional characteristics of the Error-Related Negativity (ERN) ERP component, the hallmark index of cognitive control elicited by performance errors, and which has been linked to the aMCC. The cEMG was amplified within 100 ms of error commissions (the same time-window as the ERN), particularly during the high punishment risk condition where errors would be most aversive. Furthermore, similar to the ERN, the magnitude of error cEMG predicted post-error response time slowing. Our results suggest that cEMG activity can serve as an index of avoidance motivated control, which is instrumental to adaptive cognitive control when consequences are potentially harmful. © 2013 Lindström et al.
Norberg J.,University of Stockholm |
Peira N.,University of Stockholm |
Peira N.,Stockholm Brain Institute |
Wiens S.,University of Stockholm |
Wiens S.,Stockholm Brain Institute
Psychophysiology | Year: 2010
Research suggests that processing of emotional stimulimay be eliminated if a concurrent task places sufficient demands on attentional resources. To test whether this holds for stimuli with strong emotional significance, pictures of spiders as well as mushrooms were presented at fixation to spider-fearful and non-fearful participants. Concurrently, perceptual load was manipulated in two levels with a peripheral letter discrimination task. Results of event-related potentials showed that, compared with non-fearful participants, spider-fearful participants showed greater late positive potentials (LPP) to spiders than mushrooms, which provides a manipulation check that spiders were emotionally meaningful to spider-fearful participants. Critically, this effectwas not affected by level of perceptual load. These findings suggest that strong emotional stimuli at fixation may resist manipulations of perceptual load. © 2010 Society for Psychophysiological Research.
Kubik V.,University of Stockholm |
Kubik V.,Stockholm Brain Institute |
Soderlund H.,Uppsala University |
Nilsson L.-G.,University of Stockholm |
And 3 more authors.
Experimental Psychology | Year: 2014
We investigated the individual and combined effects of enactment and testing on memory for action phrases to address whether both study techniques commonly promote item-specific processing. Participants (N = 112) were divided into four groups (n = 28). They either exclusively studied 36 action phrases (e.g., "lift the glass") or both studied and cued-recalled them in four trials. During study trials participants encoded the action phrases either by motorically performing them, or by reading them aloud, and they took final verb-cued recall tests over 18- min and 1-week retention intervals. A testing effect was demonstrated for action phrases, however, only when they were verbally encoded, and not when they were enacted. Similarly, enactive (relative to verbal) encoding reduced the rate of forgetting, but only when the action phrases were exclusively studied, and not when they were also tested. These less-than-additive effects of enactment and testing on the rate of forgetting, as well as on long-term retention, support the notion that both study techniques effectively promote item-specific processing that can only be marginally increased further by combining them. © 2014 Hogrefe Publishing.
Kadetoff D.,Stockholm Brain Institute |
Kosek E.,Stockholm Brain Institute
Journal of Rehabilitation Medicine | Year: 2010
Objective: To assess activation of the sympathetic nervous system and the hypothalamic-pituitary-adrenocortical axis during static exercise in patients with fibromyalgia. Patients and methods: Sixteen patients with fibromyalgia and 16 healthy controls performed a static knee extension until exhaustion. Plasma catecholamines, adrenocorticotropic hormone and Cortisol, as well as blood pressure and heart rate, were assessed before, during and following contraction. Plasma C reactive protein was analysed at baseline. Results: Blood pressure and heart rate increased during contraction (p < 0.001) and decreased following contraction (p<0.001) in both groups alike. Compared with baseline, plasma catecholamines increased during contraction in both groups (p<0.001), but patients with fibromyalgia had lower levels of plasma adrenaline (p<0.04) and noradrenaline (p<0.08) at all times. Adrenocorticotropic hormone increased at exhaustion in controls (p<0.001), but not in patients with fibromyalgia, who also had lower adrenocorticotropic hormone at exhaustion (p<0.02) compared with controls. There were no group differences, or changes over time in plasma Cortisol. High sensitivity C reactive protein was higher in patients with fibromyalgia compared with controls (p< 0.02). Conclusion: Patients with fibromyalgia exhibited a hypoactive sympatho-adrenal system as well as a hypo-reactive hypothalamic-pituitary axis during static exercise. Journal Compilation © 2010 Foundation of Rehabilitation Information.