| 1. |
- Majid, D. S. Adnan, et al.
(författare)
-
Neural Systems for Own-body Processing Align with Gender Identity Rather Than Birth-assigned Sex
- 2020
-
Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 30:5, s. 2897-2909
-
Tidskriftsartikel (refereegranskat)abstract
- Gender identity is a core aspect of self-identity and is usually congruent with birth-assigned sex and own body sex-perception. The neuronal circuits underlying gender identity are unknown, but greater awareness of transgenderism has sparked interest in studying these circuits. We did this by comparing brain activation and connectivity in transgender individuals (for whom gender identity and birth-assigned sex are incongruent) with that in cisgender controls (for whom they are congruent) when performing a body self-identification task during functional magnetic resonance imaging. Thirty transgender and 30 cisgender participants viewed images of their own bodies and bodies morphed in sex toward or opposite to birth-assigned sex, rating each image to the degree they identified with it. While controls identified with images of themselves, transgender individuals identified with images morphed opposite to their birth-assigned sex. After covarying out the effect of self-similarity ratings, both groups activated similar self- and body-processing systems when viewing bodies that aligned with their gender identity rather than birth-assigned sex. Additionally, transgender participants had greater limbic involvement when viewing ambiguous, androgynous images of themselves morphed toward their gender identity. These results shed light on underlying self-processing networks specific to gender identity and uncover additional involvement of emotional processing in transgender individuals.
|
|
| 2. |
- Arvidsson, Caroline, et al.
(författare)
-
Conversational production and comprehension: fMRI-evidence reminiscent of but deviant from the classical Broca–Wernicke model
- 2024
-
Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 34:3
-
Tidskriftsartikel (refereegranskat)abstract
- A key question in research on the neurobiology of language is to which extent the language production and comprehension systems share neural infrastructure, but this question has not been addressed in the context of conversation. We utilized a public fMRI dataset where 24 participants engaged in unscripted conversations with a confederate outside the scanner, via an audio-video link. We provide evidence indicating that the two systems share neural infrastructure in the left-lateralized perisylvian language network, but diverge regarding the level of activation in regions within the network. Activity in the left inferior frontal gyrus was stronger in production compared to comprehension, while comprehension showed stronger recruitment of the left anterior middle temporal gyrus and superior temporal sulcus, compared to production. Although our results are reminiscent of the classical Broca–Wernicke model, the anterior (rather than posterior) temporal activation is a notable difference from that model. This is one of the findings that may be a consequence of the conversational setting, another being that conversational production activated what we interpret as higher-level socio-pragmatic processes. In conclusion, we present evidence for partial overlap and functional asymmetry of the neural infrastructure of production and comprehension, in the above-mentioned frontal vs temporal regions during conversation.
|
|
| 3. |
- Bergström, Fredrik, 1983-, et al.
(författare)
-
Neural evidence for non-conscious working memory
- 2018
-
Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 28:9, s. 3217-3228
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 4. |
- Deluca, Vincent, et al.
(författare)
-
Mapping individual aspects of bilingual experience to adaptations in brain structure
- 2024
-
Ingår i: Cerebral Cortex. - 1047-3211 .- 1460-2199. ; 34:2
-
Tidskriftsartikel (refereegranskat)abstract
- Individual differences in using multiple languages are thought to differentially affect brain structure and function. The present study assessed the neuroanatomical predictions of an emerging theory, the Unifying the Bilingual Experience Trajectories framework, which provides the most comprehensive set of predictions of how individual differences in bilingual experiences lead to specific neural and cognitive adaptations. A total of 140 young adults with variable language experiences were scanned using magnetic resonance imaging and completed demographic questionnaires. Brain structure measures implicated in predictions of the Unifying the Bilingual Experience Trajectories model were extracted and regressed against the model's experiential factors. Consistent with the model's predictions, greater intensity and diversity of bilingual language use resulted in changes in gray matter volume in cortical regions involved in executive control (including inferior frontal gyrus, middle temporal gyrus, angular gyrus, and medial frontal gyrus), indicating adaptations toward handling increased executive control demands. Conversely, duration of bilingual engagement resulted in changes within white matter microstructure (bilateral superior longitudinal fasciculus) and increases in subcortical gray matter (left caudate), indicative of adaptations toward increased efficiency of control. Overall, this research enhances our understanding of how bilingual experiences influence brain structure and provides the first direct empirical evidence for the predictions made by the Unifying the Bilingual Experience Trajectories framework.
|
|
| 5. |
- Fjell, Anders M., et al.
(författare)
-
Poor Self-Reported Sleep is Related to Regional Cortical Thinning in Aging but not Memory Decline-Results From the Lifebrain Consortium
- 2021
-
Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 31:4, s. 1953-1969
-
Tidskriftsartikel (refereegranskat)abstract
- We examined whether sleep quality and quantity are associated with cortical and memory changes in cognitively healthy participants across the adult lifespan. Associations between self-reported sleep parameters (Pittsburgh Sleep Quality Index, PSQI) and longitudinal cortical change were tested using five samples from the Lifebrain consortium (n = 2205, 4363 MRIs, 18-92 years). In additional analyses, we tested coherence with cell-specific gene expression maps from the Allen Human Brain Atlas, and relations to changes in memory performance. "PSQI # 1 Subjective sleep quality" and "PSQI #5 Sleep disturbances" were related to thinning of the right lateral temporal cortex, with lower quality and more disturbances being associated with faster thinning. The association with "PSQI #5 Sleep disturbances" emerged after 60 years, especially in regions with high expression of genes related to oligodendrocytes and S1 pyramidal neurons. None of the sleep scales were related to a longitudinal change in episodic memory function, suggesting that sleep-related cortical changes were independent of cognitive decline. The relationship to cortical brain change suggests that self-reported sleep parameters are relevant in lifespan studies, but small effect sizes indicate that self-reported sleep is not a good biomarker of general cortical degeneration in healthy older adults.
|
|
| 6. |
- Hellerstedt, Robin, et al.
(författare)
-
Electrophysiological correlates of competitor activation predict retrieval-induced forgetting
- 2014
-
Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1460-2199 .- 1047-3211. ; 24:6, s. 1619-1629
-
Tidskriftsartikel (refereegranskat)abstract
- The very act of retrieval modifies the accessibility of memory for knowledge and past events and can also cause forgetting. A prominent theory of such retrieval-induced forgetting holds that retrieval recruits inhibition to overcome interference from competing memories, rendering these memories inaccessible. The present study tested a fundamental tenet of the inhibitory-control account: the competition-dependence assumption. Event-related potentials (ERPs) were recorded while participants engaged in a competitive retrieval task. Competition levels were manipulated within the retrieval task by varying the cue-item associative strength of competing items. In order to temporally separate ERP correlates of competitor activation and target retrieval, memory was probed with the sequential presentation of two cues: a category cue, to reactivate competitors, and a target cue. As predicted by the inhibitory-control account, competitors with strong compared to weak cue-competitor association were more susceptible to forgetting. Furthermore, competition-sensitive ERP modulations, elicited by the category cue, were observed over anterior regions and reflected individual differences in ensuing forgetting. The present study demonstrates ERP correlates of the reactivation of tightly bound associated memories (the competitors) and provides support for the inhibitory-control account of retrieval-induced forgetting.
|
|
| 7. |
- Herz, Noa, et al.
(författare)
-
Neuromodulation of Visual Cortex Reduces the Intensity of Intrusive Memories
- 2022
-
Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 32:2, s. 408-417
-
Tidskriftsartikel (refereegranskat)abstract
- Aversive events can be reexperienced as involuntary and spontaneous mental images of the event. Given that the vividness of retrieved mental images is coupled with elevated visual activation, we tested whether neuromodulation of the visual cortex would reduce the frequency and negative emotional intensity of intrusive memories. Intrusive memories of a viewed trauma film and their accompanied emotional intensity were recorded throughout 5 days. Functional connectivity, measured with resting-state functional magnetic resonance imaging prior to film viewing, was used as predictive marker for intrusions-related negative emotional intensity. Results indicated that an interaction between the visual network and emotion processing areas predicted intrusions' emotional intensity. To test the causal influence of early visual cortex activity on intrusions' emotional intensity, participants' memory of the film was reactivated by brief reminders 1 day following film viewing, followed by inhibitory 1 Hz repetitive transcranial magnetic stimulation (rTMS) over early visual cortex. Results showed that visual cortex inhibitory stimulation reduced the emotional intensity of later intrusions, while leaving intrusion frequency and explicit visual memory intact. Current findings suggest that early visual areas constitute a central node influencing the emotional intensity of intrusive memories for negative events. Potential neuroscience-driven intervention targets designed to downregulate the emotional intensity of intrusive memories are discussed.
|
|
| 8. |
- Johansson, Mikael, et al.
(författare)
-
When remembering causes forgetting: Electrophysiological correlates of retrieval-induced forgetting
- 2007
-
Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1460-2199 .- 1047-3211. ; 17:6, s. 1335-1341
-
Tidskriftsartikel (refereegranskat)abstract
- People tend to forget information that is related to memories they are actively trying to retrieve. On the basis of results from behavioral studies, such retrieval-induced forgetting is held to result from inhibitory control processes that are recruited to attenuate interference caused by competing memory traces. Employing electrophysiological measures of brain activity, the present study examined the neural correlates of these inhibitory processes as they operate. The results demonstrate that sustained prefrontal event-related potentials were 1) related to whether or not selective memory retrieval was required during reprocessing of previously studied words and 2) predictive of individual differences in the amount of forgetting observed in an ensuing recall test. The present findings give support to an inhibitory control account of retrieval-induced forgetting and are in accord with the view that prefrontal regions play an important role in the selection and maintenance of relevant memory representations at the expense of those currently irrelevant.
|
|
| 9. |
- Lövdén, Martin, et al.
(författare)
-
Performance-Related Increases in Hippocampal N-acetylaspartate (NAA) Induced by Spatial Navigation Training Are Restricted to BDNF Val Homozygotes
- 2011
-
Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1460-2199 .- 1047-3211. ; 21:6, s. 1435-1442
-
Tidskriftsartikel (refereegranskat)abstract
- Recent evidence indicates experience-dependent brain volume changes in humans, but the functional and histological nature of such changes is unknown. Here, we report that adult men performing a cognitively demanding spatial navigation task every other day over 4 months display increases in hippocampal N-acetylaspartate (NAA) as measured with magnetic resonance spectroscopy. Unlike measures of brain volume, changes in NAA are sensitive to metabolic and functional aspects of neural and glia tissue and unlikely to reflect changes in microvasculature. Training-induced changes in NAA were, however, absent in carriers of the Met substitution in the brain-derived neurotrophic factor (BDNF) gene, which is known to reduce activity-dependent secretion of BDNF. Among BDNF Val homozygotes, increases in NAA were strongly related to the degree of practice-related improvement in navigation performance and normalized to pretraining levels 4 months after the last training session. We conclude that changes in demands on spatial navigation can alter hippocampal NAA concentrations, confirming epidemiological studies suggesting that mental experience may have direct effects on neural integrity and cognitive performance. BDNF genotype moderates these plastic changes, in line with the contention that gene-context interactions shape the ontogeny of complex phenotypes.
|
|
| 10. |
- Månsson, Kristoffer N. T., et al.
(författare)
-
Viewing Pictures Triggers Rapid Morphological Enlargement in the Human Visual Cortex
- 2019
-
Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 30:3, s. 851-857
-
Tidskriftsartikel (refereegranskat)abstract
- Measuring brain morphology with non-invasive structural magnetic resonance imaging is common practice, and can be used to investigate neuroplasticity. Brain morphology changes have been reported over the course of weeks, days, and hours in both animals and humans. If such short-term changes occur even faster, rapid morphological changes while being scanned could have important implications. In a randomized within-subject study on 47 healthy individuals, two high-resolution T1-weighted anatomical images were acquired (á 263 s) per individual. The images were acquired during passive viewing of pictures or a fixation cross. Two common pipelines for analyzing brain images were used: voxel-based morphometry on gray matter (GM) volume and surface-based cortical thickness. We found that the measures of both GM volume and cortical thickness showed increases in the visual cortex while viewing pictures relative to a fixation cross. The increase was distributed across the two hemispheres and significant at a corrected level. Thus, brain morphology enlargements were detected in less than 263 s. Neuroplasticity is a far more dynamic process than previously shown, suggesting that individuals’ current mental state affects indices of brain morphology. This needs to be taken into account in future morphology studies and in everyday clinical practice.
|
|
