| 1. |
- Andin, Josefine, 1979-, et al.
(författare)
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Working Memory for Signs with Poor Visual Resolution : fMRI Evidence of Reorganization of Auditory Cortex in Deaf Signers
- 2021
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 31:7, s. 3165-3176
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Tidskriftsartikel (refereegranskat)abstract
- Stimulus degradation adds to working memory load during speech processing. We investigated whether this applies to sign processing and, if so, whether the mechanism implicates secondary auditory cortex. We conducted an fMRI experiment where 16 deaf early signers (DES) and 22 hearing non-signers performed a sign-based n-back task with three load levels and stimuli presented at high and low resolution. We found decreased behavioral performance with increasing load and decreasing visual resolution, but the neurobiological mechanisms involved differed between the two manipulations and did so for both groups. Importantly, while the load manipulation was, as predicted, accompanied by activation in the frontoparietal working memory network, the resolution manipulation resulted in temporal and occipital activation. Furthermore, we found evidence of cross-modal reorganization in the secondary auditory cortex: DES had stronger activation and stronger connectivity between this and several other regions. We conclude that load and stimulus resolution have different neural underpinnings in the visual–verbal domain, which has consequences for current working memory models, and that for DES the secondary auditory cortex is involved in the binding of representations when task demands are low.
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| 2. |
- Bergersen, L H, et al.
(författare)
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Immunogold detection of L-glutamate and D-serine in small synaptic-like microvesicles in adult hippocampal astrocytes.
- 2012
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Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 22:7, s. 1690-1697
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Tidskriftsartikel (refereegranskat)abstract
- Glutamate and the N-methyl-D-aspartate receptor ligand D-serine are putative gliotransmitters. Here, we show by immunogold cytochemistry of the adult hippocampus that glutamate and D-serine accumulate in synaptic-like microvesicles (SLMVs) in the perisynaptic processes of astrocytes. The estimated concentration of fixed glutamate in the astrocytic SLMVs is comparable to that in synaptic vesicles of excitatory nerve terminals (≈ 45 and ≈ 55 mM, respectively), whereas the D-serine level is about 6 mM. The vesicles are organized in small spaced clusters located near the astrocytic plasma membrane. Endoplasmic reticulum is regularly found in close vicinity to SLMVs, suggesting that astrocytes contain functional nanodomains, where a local Ca(2+) increase can trigger release of glutamate and/or D-serine.
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| 3. |
- Cardin, Velia, et al.
(författare)
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The Organization of Working Memory Networks is Shaped by Early Sensory Experience
- 2018
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Ingår i: Cerebral Cortex. - : OXFORD UNIV PRESS INC. - 1047-3211 .- 1460-2199. ; 28:10, s. 3540-3554
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Tidskriftsartikel (refereegranskat)abstract
- Early deafness results in crossmodal reorganization of the superior temporal cortex (STC). Here, we investigated the effect of deafness on cognitive processing. Specifically, we studied the reorganization, due to deafness and sign language (SL) knowledge, of linguistic and nonlinguistic visual working memory (WM). We conducted an fMRI experiment in groups that differed in their hearing status and SL knowledge: deaf native signers, and hearing native signers, hearing nonsigners. Participants performed a 2-back WM task and a control task. Stimuli were signs from British Sign Language (BSL) or moving nonsense objects in the form of point-light displays. We found characteristic WM activations in fronto-parietal regions in all groups. However, deaf participants also recruited bilateral posterior STC during the WM task, independently of the linguistic content of the stimuli, and showed less activation in fronto-parietal regions. Resting-state connectivity analysis showed increased connectivity between frontal regions and STC in deaf compared to hearing individuals. WM for signs did not elicit differential activations, suggesting that SL WM does not rely on modality-specific linguistic processing. These findings suggest that WM networks are reorganized due to early deafness, and that the organization of cognitive networks is shaped by the nature of the sensory inputs available during development.
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| 4. |
- Igelström, Kajsa, 1980-, et al.
(författare)
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Functional connectivity between the temporoparietal cortex and cerebellum in autism spectrum disorder
- 2017
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Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 27:4, s. 2617-2627
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Tidskriftsartikel (refereegranskat)abstract
- The neural basis of autism spectrum disorder (ASD) is not yet understood. ASD is marked by social deficits and is strongly associated with cerebellar abnormalities. We studied the organization and cerebellar connectivity of the temporoparietal junction (TPJ), an area that plays a crucial role in social cognition. We applied localized independent component analysis to resting-state fMRI data from autistic and neurotypical adolescents to yield an unbiased parcellation of the bilateral TPJ into 11 independent components (ICs). A comparison between neurotypical and autistic adolescents showed that the organization of the TPJ was not significantly altered in ASD. Second, we used the time courses of the TPJ ICs as spatially unbiased “seeds” for a functional connectivity analysis applied to voxels within the cerebellum. We found that the cerebellum contained a fine-grained, lateralized map of the TPJ. The connectivity of the TPJ subdivisions with cerebellar zones showed one striking difference in ASD. The right dorsal TPJ showed markedly less connectivity with the left Crus II. Disturbed cerebellar input to this key region for cognition and multimodal integration may contribute to social deficits in ASD. The findings might also suggest that the right TPJ and/or left Crus II are potential targets for noninvasive brain stimulation therapies.
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| 5. |
- Koppel, Lina, et al.
(författare)
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Prediction and action in cortical pain processing
- 2023
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Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 33:1, s. 794-810
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Tidskriftsartikel (refereegranskat)abstract
- Predicting that a stimulus is painful facilitates action to avoid harm. But how distinct are the neural processes underlying the prediction of upcoming painful events vis-a-vis those taking action to avoid them? Here, we investigated brain activity as a function of current and predicted painful or nonpainful thermal stimulation, as well as the ability of voluntary action to affect the duration of upcoming stimulation. Participants performed a task which involved the administration of a painful or nonpainful stimulus (S1), which predicted an immediately subsequent very painful or nonpainful stimulus (S2). Pressing a response button within a specified time window during S1 either reduced or did not reduce the duration of the upcoming stimulation. Predicted pain increased activation in several regions, including anterior cingulate cortex (ACC), midcingulate cortex (MCC), and insula; however, activation in ACC and MCC depended on whether a meaningful action was performed, with MCC activation showing a direct relationship with motor output. Insulas responses for predicted pain were also modulated by potential action consequences, albeit without a direct relationship with motor output. These findings suggest that cortical pain processing is not specifically tied to the sensory stimulus, but instead, depends on the consequences of that stimulus for sensorimotor control of behavior.
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| 6. |
- Larsson, Max, et al.
(författare)
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Functional and anatomical identification of a vesicular transporter mediating neuronal ATP release.
- 2012
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 22:5, s. 1203-1214
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Tidskriftsartikel (refereegranskat)abstract
- ATP is known to be coreleased with glutamate at certain central synapses. However, the nature of its release is controversial. Here, we demonstrate that ATP release from cultured rat hippocampal neurons is sensitive to RNAi-mediated knockdown of the recently identified vesicular nucleotide transporter (VNUT or SLC17A9). In the intact brain, light microscopy showed particularly strong VNUT immunoreactivity in the cerebellar cortex, the olfactory bulb, and the hippocampus. Using immunoelectron microscopy, we found VNUT immunoreactivity colocalized with synaptic vesicles in excitatory and inhibitory terminals in the hippocampal formation. Moreover, VNUT immunolabeling, unlike that of the vesicular glutamate transporter VGLUT1, was enriched in preterminal axons and present in postsynaptic dendritic spines. Immunoisolation of synaptic vesicles indicated presence of VNUT in a subset of VGLUT1-containing vesicles. Thus, we conclude that VNUT mediates transport of ATP into synaptic vesicles of hippocampal neurons, thereby conferring a purinergic phenotype to these cells.
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| 7. |
- Lindström, Sarah, et al.
(författare)
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VGluT1 Deficiency Impairs Visual Attention and Reduces the Dynamic Range of Short-Term Plasticity at Corticothalamic Synapses
- 2020
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Ingår i: Cerebral Cortex. - : OXFORD UNIV PRESS INC. - 1047-3211 .- 1460-2199. ; 30:3, s. 1813-1829
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Tidskriftsartikel (refereegranskat)abstract
- The most common excitatory neurotransmitter in the central nervous system, glutamate, is loaded into synaptic vesicles by vesicular glutamate transporters (VGluTs). The primary isoforms, VGluT1 and 2, are expressed in complementary patterns throughout the brain and correlate with short-term synaptic plasticity. VGluT1 deficiency is observed in certain neurological disorders, and hemizygous (VGluT1(+/-)) mice display increased anxiety and depression, altered sensorimotor gating, and impairments in learning and memory. The synaptic mechanisms underlying these behavioral deficits are unknown. Here, we show that VGluT1(+/-) mice had decreased visual processing speeds during a sustained visual-spatial attention task. Furthermore, in vitro recordings of corticothalamic (CT) synapses revealed dramatic reductions in short-term facilitation, increased initial release probability, and earlier synaptic depression in VGluT1+/- mice. Our electron microscopy results show that VGluT1 concentration is reduced at CT synapses of hemizygous mice, but other features (such as vesicle number and active zone size) are unchanged. We conclude that VGluT1-haploinsuficiency decreases the dynamic range of gain modulation provided by CT feedback to the thalamus, and this deficiency contributes to the observed attentional processing deficit. We further hypothesize that VGluT1 concentration regulates release probability by applying a "brake" to an unidentified presynaptic protein that typically acts as a positive regulator of release.
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| 8. |
- Olesen, Pernille, et al.
(författare)
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Brain activity related to working memory and distraction in children and adults
- 2007
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 17:5, s. 1047-1054
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Tidskriftsartikel (refereegranskat)abstract
- In order to retain information in working memory (WM) during a delay, distracting stimuli must be ignored. This important ability improves during childhood, but the neural basis for this development is not known. We measured brain activity with functional magnetic resonance imaging in adults and 13-year-old children. Data were analyzed with an event-related design to isolate activity during cue, delay, distraction, and response selection. Adults were more accurate and less distractible than children. Activity in the middle frontal gyrus and intraparietal cortex was stronger in adults than in children during the delay, when information was maintained in WM. Distraction during the delay evoked activation in parietal and occipital cortices in both adults and children. However, distraction activated frontal cortex only in children. The larger frontal activation in response to distracters presented during the delay may explain why children are more susceptible to interfering stimuli.
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| 9. |
- Padilla, Nelly, et al.
(författare)
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Disrupted resting-sate brain network dynamics in children born extremely preterm
- 2023
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Ingår i: Cerebral Cortex. - : OXFORD UNIV PRESS INC. - 1047-3211 .- 1460-2199. ; 33:13, s. 8101-8109
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Tidskriftsartikel (refereegranskat)abstract
- The developing brain has to adapt to environmental and intrinsic insults after extremely preterm (EPT) birth. Ongoing maturational processes maximize their fit to the environment and this can provide a substrate for neurodevelopmental failures. Resting-state functional magnetic resonance imaging was used to scan 33 children born EPT, at < 27 weeks of gestational age, and 26 full-term controls at 10 years of age. We studied the capability of a brain area to propagate neural information (intrinsic ignition) and its variability across time (node-metastability). This framework was computed for the dorsal attention network (DAN), frontoparietal, default-mode network (DMN), and the salience, limbic, visual, and somatosensory networks. The EPT group showed reduced intrinsic ignition in the DMN and DAN, compared with the controls, and reduced node-metastability in the DMN, DAN, and salience networks. Intrinsic ignition and node-metastability values correlated with cognitive performance at 12 years of age in both groups, but only survived in the term group after adjustment. Preterm birth disturbed the signatures of functional brain organization at rest in 3 core high-order networks: DMN, salience, and DAN. Identifying vulnerable resting-state networks after EPT birth may lead to interventions that aim to rebalance brain function.
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| 10. |
- Perini, Irene, et al.
(författare)
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Mutation Carriers with Reduced C-Afferent Density Reveal Cortical Dynamics of Pain-Action Relationship during Acute Pain
- 2020
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Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 30:9, s. 4858-4870
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Tidskriftsartikel (refereegranskat)abstract
- The evidence that action shapes perception has become widely accepted, for example, in the domain of vision. However, the manner in which action-relevant factors might influence the neural dynamics of acute pain processing has remained underexplored, particularly the functional roles of anterior insula (AI) and midanterior cingulate cortex (mid-ACC), which are frequently implicated in acute pain. To address this, we examined a unique group of heterozygous carriers of the rare R221W mutation on the nerve growth factor (NGF) gene. R221W carriers show a congenitally reduced density of C-nociceptor afferent nerves in the periphery, but can nonetheless distinguish between painful and nonpainful stimulations. Despite this, carriers display a tendency to underreact to acute pain behaviorally, thus exposing a potential functional gap in the pain-action relationship and allowing closer investigation of how the brain integrates pain and action information. Heterozygous R221W carriers and matched controls performed a functional magnetic resonance imaging (fMRI) task designed to dissociate stimulus type (painful or innocuous) from current behavioral relevance (relevant or irrelevant), by instructing participants to either press or refrain from pressing a button during thermal stimulation. Carriers subjective pain thresholds did not differ from controls, but the carrier group showed decreased task accuracy. Hemodynamic activation in AI covaried with task performance, revealing a functional role in pain-action integration with increased responses for task-relevant painful stimulation ("signal," requiring button-press execution) over task-irrelevant stimulation ("noise," requiring button-press suppression). As predicted, mid-ACC activation was associated with action execution regardless of pain. Functional connectivity between AI and mid-ACC increased as a function of reported urge to withdraw from the stimulus, suggesting a joint role for these regions in motivated action during pain. The carrier group showed greater activation of primary sensorimotor cortices-but not the AI and mid-ACC regions-during pain and action, suggesting compensatory processing. These findings indicate a critical role for the AI-mid-ACC axis in supporting a flexible, adaptive action selection during pain, alongside the accompanying subjective experience of an urge to escape the pain.
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