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Eriksson, Johan
Publications (10 of 42) Show all publications
Karlsson Wirebring, L., Stillesjö, S., Eriksson, J., Juslin, P. & Nyberg, L. (2018). A Similarity-Based Process for Human Judgment in the Parietal Cortex. Frontiers in Human Neuroscience, 12, Article ID 481.
Open this publication in new window or tab >>A Similarity-Based Process for Human Judgment in the Parietal Cortex
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2018 (English)In: Frontiers in Human Neuroscience, ISSN 1662-5161, E-ISSN 1662-5161, Vol. 12, article id 481Article in journal (Refereed) Published
Abstract [en]

One important distinction in psychology is between inferences based on associative memory and inferences based on analysis and rules. Much previous empirical work conceive of associative and analytical processes as two exclusive ways of addressing a judgment task, where only one process is selected and engaged at a time, in an either-or fashion. However, related work indicate that the processes are better understood as being in interplay and simultaneously engaged. Based on computational modeling and brain imaging of spontaneously adopted judgment strategies together with analyses of brain activity elicited in tasks where participants were explicitly instructed to perform similarity-based associative judgments or rule-based judgments (n = 74), we identified brain regions related to the two types of processes. We observed considerable overlap in activity patterns. The precuneus was activated for both types of judgments, and its activity predicted how well a similarity-based model fit the judgments. Activity in the superior frontal gyrus predicted the fit of a rule-based judgment model. The results suggest the precuneus as a key node for similarity-based judgments, engaged both when overt responses are guided by similarity-based and rule-based processes. These results are interpreted such that similarity-based processes are engaged in parallel to rule-based-processes, a finding with direct implications for cognitive theories of judgment.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2018
Keywords
judgment and decision-making, fMRI, exemplar model, multiple-cue judgment, cognitive model
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-154869 (URN)10.3389/fnhum.2018.00481 (DOI)000453235900001 ()2-s2.0-85058995922 (Scopus ID)
Available from: 2019-01-04 Created: 2019-01-04 Last updated: 2019-01-04Bibliographically approved
Ekman, U., Fordell, H., Eriksson, J., Lenfeldt, N., Wåhlin, A., Eklund, A. & Malm, J. (2018). Increase of frontal neuronal activity in chronic neglect after training in virtual reality. Acta Neurologica Scandinavica, 138(4), 284-292
Open this publication in new window or tab >>Increase of frontal neuronal activity in chronic neglect after training in virtual reality
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2018 (English)In: Acta Neurologica Scandinavica, ISSN 0001-6314, E-ISSN 1600-0404, Vol. 138, no 4, p. 284-292Article in journal (Refereed) Published
Abstract [en]

Objectives: A third of patients with stroke acquire spatial neglect associated with poor rehabilitation outcome. New effective rehabilitation interventions are needed. Scanning training combined with multisensory stimulation to enhance the rehabilitation effect is suggested. In accordance, we have designed a virtual-reality based scanning training that combines visual, audio and sensori-motor stimulation called RehAtt((R)). Effects were shown in behavioural tests and activity of daily living. Here, we use fMRI to evaluate the change in brain activity during Posners Cuing Task (attention task) after RehAtt((R)) intervention, in patients with chronic neglect.

Methods: Twelve patients (mean age=72.7years, SD=6.1) with chronic neglect (persistent symptoms >6months) performed the interventions 3 times/wk during 5weeks, in total 15hours. Training effects on brain activity were evaluated using fMRI task-evoked responses during the Posners cuing task before and after the intervention.

Results: Patients improved their performance in the Posner fMRI task. In addition, patients increased their task-evoked brain activity after the VR interventions in an extended network including pre-frontal and temporal cortex during attentional cueing, but showed no training effects during target presentations.

Conclusions: The current pilot study demonstrates that a novel multisensory VR intervention has the potential to benefit patients with chronic neglect in respect of behaviour and brain changes. Specifically, the fMRI results show that strategic processes (top-down control during attentional cuing) were enhanced by the intervention. The findings increase knowledge of the plasticity processes underlying positive rehabilitation effects from RehAtt((R)) in chronic neglect.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
cognitive rehabilitation, functional magnetic resonance imaging, neuronal plasticity, spatial neglect, virtual reality
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-152199 (URN)10.1111/ane.12955 (DOI)000443931400003 ()29770439 (PubMedID)
Available from: 2018-10-31 Created: 2018-10-31 Last updated: 2018-10-31Bibliographically approved
Bergström, F. & Eriksson, J. (2018). Neural evidence for non-conscious working memory. Cerebral Cortex, 28(9), 3217-3228
Open this publication in new window or tab >>Neural evidence for non-conscious working memory
2018 (English)In: Cerebral Cortex, ISSN 1047-3211, E-ISSN 1460-2199, Vol. 28, no 9, p. 3217-3228Article in journal (Refereed) Published
Abstract [en]

Recent studies have found that non-consciously perceived information can be retained for several seconds, a feat that has been attributed to non-conscious working memory processes. However, these studies have mainly relied on subjective measures of visual experience, and the neural processes responsible for non-conscious short-term retention remains unclear. Here we used continuous flash suppression to render stimuli non-conscious in a delayed match-to-sample task together with fMRI to investigate the neural correlates of non-conscious short-term (5-15 s) retention. The participants' behavioral performance was at chance level when they reported no visual experience of the sample stimulus. Critically, multivariate pattern analyses of BOLD signal during the delay phase could classify presence versus absence of sample stimuli based on signal patterns in frontal cortex, and its spatial position based on signal patterns in occipital cortex. In addition, univariate analyses revealed increased BOLD signal change in prefrontal regions during memory recognition. Thus, our findings demonstrate short-term maintenance of information presented non-consciously, defined by chance performance behaviorally. This non-consciously retained information seems to rely on persistent neural activity in frontal and occipital cortex, and may engage further cognitive control processes during memory recognition.

Place, publisher, year, edition, pages
Oxford University Press, 2018
Keywords
consciousness, continuous flash suppression, fMRI, unconscious, subjective measure, working memory
National Category
Neurosciences Psychology
Identifiers
urn:nbn:se:umu:diva-124806 (URN)10.1093/cercor/bhx193 (DOI)000443545600012 ()28981609 (PubMedID)
Funder
Swedish Research CouncilEU, FP7, Seventh Framework Programme, 604102
Note

Originally included in thesis in manuscript form with title "Neural evidence for non-conscious short-term memory".

Available from: 2016-08-25 Created: 2016-08-25 Last updated: 2018-10-25Bibliographically approved
Berginström, N., Nordström, P., Ekman, U., Eriksson, J., Nyberg, L. & Nordström, A. (2018). Pharmaco-fMRI in Patients With Traumatic Brain Injury: A Randomized Controlled Trial With the Monoaminergic Stabilizer (-)-OSU6162. The journal of head trauma rehabilitation
Open this publication in new window or tab >>Pharmaco-fMRI in Patients With Traumatic Brain Injury: A Randomized Controlled Trial With the Monoaminergic Stabilizer (-)-OSU6162
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2018 (English)In: The journal of head trauma rehabilitation, ISSN 0885-9701, E-ISSN 1550-509XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

OBJECTIVE: To examine the effects of monoaminergic stabilizer (-)-OSU6162 on brain activity, as measured by blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI), in patients in the chronic phase of traumatic brain injury suffering from fatigue.

SETTING: Neurorehabilitation clinic.

PARTICIPANTS: Patients with traumatic brain injury received either placebo (n = 24) or active treatment (n = 28). Healthy controls (n = 27) went through fMRI examination at one point and were used in sensitivity analysis on normalization of BOLD response.

DESIGN: Randomized, double-blinded, placebo-controlled design.

MAIN MEASURES: Effects on BOLD signal changes from before to after treatment during performance of a fatiguing attention task.

RESULTS: The fMRI results revealed treatment effects within the right occipitotemporal cortex and the right orbitofrontal cortex. In these regions, the BOLD response was normalized relative to healthy controls at the postintervention fMRI session. No effects were seen in regions in which we previously observed activity differences between patients and healthy controls while performing this fMRI task, such as the striatum.

CONCLUSION: (-)-OSU6162 treatment had influences on functional brain activity, although the normalized regional BOLD response was observed in regions that were not a priori hypothesized to be sensitive to this particular treatment, and was not accompanied by any effects on in-scanner test performance or on fatigue.

Place, publisher, year, edition, pages
Wolters Kluwer, 2018
National Category
Neurology Neurosciences
Identifiers
urn:nbn:se:umu:diva-152090 (URN)10.1097/HTR.0000000000000440 (DOI)30234850 (PubMedID)
Funder
Ragnar Söderbergs stiftelseTorsten Söderbergs stiftelseKnut and Alice Wallenberg FoundationVästerbotten County Council
Available from: 2018-09-26 Created: 2018-09-26 Last updated: 2019-02-20
Berginström, N., Nordström, P., Ekman, U., Eriksson, J., Andersson, M., Nyberg, L. & Nordström, A. (2018). Using Functional Magnetic Resonance Imaging to Detect Chronic Fatigue in Patients With Previous Traumatic Brain Injury: changes linked to altered Striato-Thalamic-Cortical Functioning. The journal of head trauma rehabilitation, 33(4), 266-274
Open this publication in new window or tab >>Using Functional Magnetic Resonance Imaging to Detect Chronic Fatigue in Patients With Previous Traumatic Brain Injury: changes linked to altered Striato-Thalamic-Cortical Functioning
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2018 (English)In: The journal of head trauma rehabilitation, ISSN 0885-9701, E-ISSN 1550-509X, Vol. 33, no 4, p. 266-274Article in journal (Refereed) Published
Abstract [en]

Objective: To investigate whether functional magnetic resonance imaging (fMRI) can be used to detect fatigue after traumatic brain injury (TBI).

Setting: Neurorehabilitation clinic.

Participants: Patients with TBI (n = 57) and self-experienced fatigue more than 1 year postinjury, and age- and gender-matched healthy controls (n = 27).

Main Measures: Self-assessment scales of fatigue, a neuropsychological test battery, and fMRI scanning during performance of a fatiguing 27-minute attention task.

Results: During testing within the fMRI scanner, patients showed a higher increase in self-reported fatigue than controls from before to after completing the task (P < .001).The patients also showed lower activity in several regions, including bilateral caudate, thalamus, and anterior insula (all P < .05). Furthermore, the patients failed to display decreased activation over time in regions of interest: the bilateral caudate and anterior thalamus (all P < .01). Left caudate activity correctly identified 91% of patients and 81% of controls, resulting in a positive predictive value of 91%.

Conclusion: The results suggest that chronic fatigue after TBI is associated with altered striato-thalamic-cortical functioning. It would be of interest to study whether fMRI can be used to support the diagnosis of chronic fatigue in future studies.

Place, publisher, year, edition, pages
Wolters Kluwer, 2018
Keywords
fatigue, functional magnetic resonance imaging, neuropsychology, traumatic brain injury
National Category
Neurology
Research subject
Rehabilitation Medicine
Identifiers
urn:nbn:se:umu:diva-140021 (URN)10.1097/HTR.0000000000000340 (DOI)000442745900013 ()
Funder
Västerbotten County CouncilTorsten Söderbergs stiftelse
Available from: 2017-09-29 Created: 2017-09-29 Last updated: 2019-01-15Bibliographically approved
Eriksson, J. (2017). Activity in part of the neural correlates of consciousness reflects integration. Consciousness and Cognition, 55, 26-34
Open this publication in new window or tab >>Activity in part of the neural correlates of consciousness reflects integration
2017 (English)In: Consciousness and Cognition, ISSN 1053-8100, E-ISSN 1090-2376, Vol. 55, p. 26-34Article in journal (Refereed) Published
Abstract [en]

Integration is commonly viewed as a key process for generating conscious experiences. Accordingly, there should be increased activity within the neural correlates of consciousness when demands on integration increase. We used fMRI and "informational masking" to isolate the neural correlates of consciousness and measured how the associated brain activity changed as a function of required integration. Integration was manipulated by comparing the experience of hearing simple reoccurring tones to hearing harmonic tone triplets. The neural correlates of auditory consciousness included superior temporal gyrus, lateral and medial frontal regions, cerebellum, and also parietal cortex. Critically, only activity in left parietal cortex increased significantly as a function of increasing demands on integration. We conclude that integration can explain part of the neural activity associated with the generation conscious experiences, but that much of associated brain activity apparently reflects other processes.

Keywords
auditory, brain, consciousness, fMRI, integration
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-141489 (URN)10.1016/j.concog.2017.07.007 (DOI)000413130300003 ()28753443 (PubMedID)
Available from: 2017-11-20 Created: 2017-11-20 Last updated: 2018-06-09Bibliographically approved
Berginström, N., Nordström, P., Ekman, U., Eriksson, J., Andersson, M., Nyberg, L. & Nordström, A. (2017). Fatigue after traumatic brain injury is linked to altered striato-thalamic-cortical functioning. In: Brain Injury: Accepted Abstracts from the International Brain Injury Association’s 12th World Congress on Brain Injury. Paper presented at International Brain Injury Association’s 12th World Congress on Brain Injury (pp. 755-755). , 31
Open this publication in new window or tab >>Fatigue after traumatic brain injury is linked to altered striato-thalamic-cortical functioning
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2017 (English)In: Brain Injury: Accepted Abstracts from the International Brain Injury Association’s 12th World Congress on Brain Injury, 2017, Vol. 31, p. 755-755Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Mental fatigue is a common symptom in the chronic phase of traumatic brain injury. Despite its high prevalence, no treatmentis available for this disabling symptom, and the mechanisms underlying fatigue are poorly understood. Some studies have suggested that fatigue in traumatic brain injury and other neurological disorders might reflect dysfunction within striato-thalamic-cortical loops. In the present study, we investigated whether functional magnetic resonance imaging(fMRI) can be used to detect chronic fatigue after traumatic brain injury (TBI), with emphasis on the striato-thalamic cortical-loops. We included patients who had suffered traumatic brain injury (n = 57, age range 20–64 years) and experienced mental fatigue > 1 year post injury (mean = 8.79 years, SD = 7.35), and age- and sex-matched healthycontrols (n = 27, age range 25–65 years). All participants completed self-assessment scales of fatigue and other symptoms, underwent an extensive neuropsychological test battery and performed a fatiguing 27-minute attention task (the modified Symbol Digit Modalities Test) during fMRI. Accuracy did not differ between groups, but reaction times were slower in the traumatic brain injury group (p < 0.001). Patients showed a greater increase in fatigue than controls from before to after task completion (p < 0.001). Patients showed less fMRI blood oxygen level–dependent activity in several a priori hypothesized regions (family-wise error corrected,p < 0.05), including the bilateral caudate, thalamus and anterior insula. Using the left caudate as a region of interest and testing for sensitivity and specificity, we identified 91% of patients and 81% of controls. As expected, controls showed decreased activation over time in regions of interest—the bilateral caudate and anterior thalamus (p < 0.002, uncorrected)—whereas patients showed no corresponding activity decrease. These results suggest that chronic fatigue after TBI is linked to altered striato-thalamic-cortical functioning. The high precision of fMRI for the detection of fatigue is of great clinical interest, given the lack of objective measures for the diagnosis of fatigue.

National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-138649 (URN)10.1080/02699052.2017.1312145 (DOI)000406734000076 ()
Conference
International Brain Injury Association’s 12th World Congress on Brain Injury
Available from: 2017-08-25 Created: 2017-08-25 Last updated: 2018-06-09
Nyberg, L. & Eriksson, J. (2016). Working Memory: Maintenance, Updating, and the Realization of Intentions. Cold Spring Harbor Perspectives in Biology, 8(2), Article ID a021816.
Open this publication in new window or tab >>Working Memory: Maintenance, Updating, and the Realization of Intentions
2016 (English)In: Cold Spring Harbor Perspectives in Biology, ISSN 1943-0264, E-ISSN 1943-0264, Vol. 8, no 2, article id a021816Article in journal (Refereed) Published
Abstract [en]

"Working memory" refers to avast set of mnemonic processes and associated brain networks, relates to basic intellectual abilities, and underlies many real-world functions. Working-memory maintenance involves frontoparietal regions and distributed representational areas, and can be based on persistent activity in reentrant loops, synchronous oscillations, or changes in synaptic strength. Manipulation of content of working memory depends on the dorsofrontal cortex, and updating is realized by a frontostriatal '"gating" function. Goals and intentions are represented as cognitive and motivational contexts in the rostrofrontal cortex. Different working-memory networks are linked via associative reinforcement-learning mechanisms into a self-organizing system. Normal capacity variation, as well as working-memory deficits, can largely be accounted for by the effectiveness and integrity of the basal ganglia and dopaminergic neurotransmission.

National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-118399 (URN)10.1101/cshperspect.a021816 (DOI)000371181300006 ()
Available from: 2016-04-13 Created: 2016-03-18 Last updated: 2018-06-07Bibliographically approved
Karlsson Wirebring, L., Wiklund-Hörnqvist, C., Eriksson, J., Andersson, M., Jonsson, B. & Nyberg, L. (2015). Lesser neural pattern similarity across repeated tests is associated with better long-term memory retention. Journal of Neuroscience, 35(26), 9595-9602
Open this publication in new window or tab >>Lesser neural pattern similarity across repeated tests is associated with better long-term memory retention
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2015 (English)In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 35, no 26, p. 9595-9602Article in journal (Refereed) Published
Abstract [en]

Encoding and retrieval processes enhance long-term memory performance. The efficiency of encoding processes has recently been linked to representational consistency: the reactivation of a representation that gets more specific each time an item is further studied. Here we examined the complementary hypothesis of whether the efficiency of retrieval processes also is linked to representational consistency. Alternatively, recurrent retrieval might foster representational variability—the altering or adding of underlying memory representa- tions. Human participants studied 60 Swahili–Swedish word pairs before being scanned with fMRI the same day and 1 week later. On Day 1, participants were tested three times on each word pair, and on Day 7 each pair was tested once. A BOLD signal change in right superior parietal cortex was associated with subsequent memory on Day 1 and with successful long-term retention on Day 7. A representational similarity analysis in this parietal region revealed that beneficial recurrent retrieval was associated with representational variability, such that the pattern similarity on Day 1 was lower for retrieved words subsequently remembered compared with those subsequently forgot- ten. This was mirrored by a monotonically decreased BOLD signal change in dorsolateral prefrontal cortex on Day 1 as a function of repeated successful retrieval for words subsequently remembered, but not for words subsequently forgotten. This reduction in prefrontal response could reflect reduced demands on cognitive control. Collectively, the results offer novel insights into why memory retention benefits from repeated retrieval, and they suggest fundamental differences between repeated study and repeated testing. 

Place, publisher, year, edition, pages
Society for Neuroscience, 2015
Keywords
fMRI, memory, pattern similarity, repeated testing, retrieval, RSA
National Category
Psychology Physiology
Identifiers
urn:nbn:se:umu:diva-96392 (URN)10.1523/JNEUROSCI.3550-14.2015 (DOI)000358252600007 ()
Available from: 2014-11-19 Created: 2014-11-19 Last updated: 2018-06-07Bibliographically approved
Eriksson, J., Vogel, E. K., Lansner, A., Bergström, F. & Nyberg, L. (2015). Neurocognitive Architecture of Working Memory. Neuron, 88(1), 33-46
Open this publication in new window or tab >>Neurocognitive Architecture of Working Memory
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2015 (English)In: Neuron, ISSN 0896-6273, E-ISSN 1097-4199, Vol. 88, no 1, p. 33-46Article, review/survey (Refereed) Published
Abstract [en]

A crucial role for working memory in temporary information processing and guidance of complex behavior has been recognized for many decades. There is emerging consensus that working-memory maintenance results from the interactions among long-term memory representations and basic processes, including attention, that are instantiated as reentrant loops between frontal and posterior cortical areas, as well as sub-cortical structures. The nature of such interactions can account for capacity limitations, lifespan changes, and restricted transfer after working-memory training. Recent data and models indicate that working memory may also be based on synaptic plasticity and that working memory can operate on non-consciously perceived information.

Keywords
Memory
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-111764 (URN)10.1016/j.neuron.2015.09.020 (DOI)000363782500004 ()26447571 (PubMedID)2-s2.0-84943249357 (Scopus ID)
Available from: 2015-11-23 Created: 2015-11-23 Last updated: 2018-06-07Bibliographically approved
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