Search Results Heading

MBRLSearchResults

mbrl.module.common.modules.added.book.to.shelf
Title added to your shelf!
View what I already have on My Shelf.
Oops! Something went wrong.
Oops! Something went wrong.
While trying to add the title to your shelf something went wrong :( Kindly try again later!
Are you sure you want to remove the book from the shelf?
Oops! Something went wrong.
Oops! Something went wrong.
While trying to remove the title from your shelf something went wrong :( Kindly try again later!
    Done
    Filters
    Reset
  • Discipline
      Discipline
      Clear All
      Discipline
  • Is Peer Reviewed
      Is Peer Reviewed
      Clear All
      Is Peer Reviewed
  • Item Type
      Item Type
      Clear All
      Item Type
  • Subject
      Subject
      Clear All
      Subject
  • Year
      Year
      Clear All
      From:
      -
      To:
  • More Filters
502 result(s) for "Parahippocampal Gyrus - physiology"
Sort by:
Psilocybin-induced spiritual experiences and insightfulness are associated with synchronization of neuronal oscillations
Rationale During the last years, considerable progress has been made toward understanding the neuronal basis of consciousness by using sophisticated behavioral tasks, brain-imaging techniques, and various psychoactive drugs. Nevertheless, the neuronal mechanisms underlying some of the most intriguing states of consciousness, including spiritual experiences, remain unknown. Objectives To elucidate state of consciousness-related neuronal mechanisms, human subjects were given psilocybin, a naturally occurring serotonergic agonist and hallucinogen that has been used for centuries to induce spiritual experiences in religious and medical rituals. Methods In this double-blind, placebo-controlled study, 50 healthy human volunteers received a moderate dose of psilocybin, while high-density electroencephalogram (EEG) recordings were taken during eyes-open and eyes-closed resting states. The current source density and the lagged phase synchronization of neuronal oscillations across distributed brain regions were computed and correlated with psilocybin-induced altered states of consciousness. Results Psilocybin decreased the current source density of neuronal oscillations at 1.5–20 Hz within a neural network comprising the anterior and posterior cingulate cortices and the parahippocampal regions. Most intriguingly, the intensity levels of psilocybin-induced spiritual experience and insightfulness correlated with the lagged phase synchronization of delta oscillations (1.5–4 Hz) between the retrosplenial cortex, the parahippocampus, and the lateral orbitofrontal area. Conclusions These results provide systematic evidence for the direct association of a specific spatiotemporal neuronal mechanism with spiritual experiences and enhanced insight into life and existence. The identified mechanism may constitute a pathway for modulating mental health, as spiritual experiences can promote sustained well-being and psychological resilience.
Simple line drawings suffice for functional MRI decoding of natural scene categories
Humans are remarkably efficient at categorizing natural scenes. In fact, scene categories can be decoded from functional MRI (fMRI) data throughout the ventral visual cortex, including the primary visual cortex, the parahippocampal place area (PPA), and the retrosplenial cortex (RSC). Here we ask whether, and where, we can still decode scene category if we reduce the scenes to mere lines. We collected fMRI data while participants viewed photographs and line drawings of beaches, city streets, forests, highways, mountains, and offices. Despite the marked difference in scene statistics, we were able to decode scene category from fMRI data for line drawings just as well as from activity for color photographs, in primary visual cortex through PPA and RSC. Even more remarkably, in PPA and RSC, error patterns for decoding from line drawings were very similar to those from color photographs. These data suggest that, in these regions, the information used to distinguish scene category is similar for line drawings and photographs. To determine the relative contributions of local and global structure to the human ability to categorize scenes, we selectively removed long or short contours from the line drawings. In a category-matching task, participants performed significantly worse when long contours were removed than when short contours were removed. We conclude that global scene structure, which is preserved in line drawings, plays an integral part in representing scene categories.
Neural Correlates of Receiving an Apology and Active Forgiveness: An fMRI Study
Interpersonal conflicts are a common element of many social relationships. One possible process in rebuilding social relationships is the act of apologizing. Behavioral studies have shown that apologies promote forgiveness. However, the neural bases of receiving an apology and forgiveness are still unknown. Hence, the aim of the present fMRI study was to investigate brain processes involved in receiving an apology and active forgiveness of an ambiguous offense. We asked one group of participants (player A) to make decisions, which were either positive or negative for another group of participants (player B). The intention of player A was ambiguous to player B. In case of a negative impact, participants in the role of player A could send an apology message to participants in the role of player B. Subsequently players B were asked whether they wanted to forgive player A for making a decision with negative consequences. We found that receiving an apology yielded activation in the left inferior frontal gyrus, the left middle temporal gyrus, and left angular gyrus. In line with previous research we found that forgiving judgments activated the right angular gyrus.
Neuroimaging predictors of creativity in healthy adults
Neuroimaging has revealed numerous neural predictors of individual differences in creativity; however, with most of these identified in only one study, sometimes involving very small samples, their reliability is uncertain. To contribute to a convergent cognitive neuroscience of creativity, we conducted a pre-registered conceptual replication and extension study in which we assessed previously reported predictors of creativity using a multimodal approach, incorporating volumetric, white matter, and functional connectivity neuroimaging data. We assessed sets of pre-registered predictors against prevailing measures of creativity, including visual and verbal tests of divergent thinking, everyday creative behaviour, and creative achievement. We then conducted whole-brain exploratory analyses. Greater creativity was broadly predicted by features of the inferior frontal gyrus (IFG) and inferior parietal lobe (IPL), including both local grey matter and white matter predictors in the IFG, the superior longitudinal fasciculus that connects them, and IFG-IPL functional connectivity. As IFG and IPL are important nodes within executive control and default mode networks (DMN), respectively, this result supports the view that executive modulation of DMN activity optimizes creative ideation. Furthermore, white matter integrity of the basal ganglia was also a generalizable creativity predictor, and exploratory analyses revealed the anterior lobe of the cerebellum and the parahippocampal gyrus to both be reliable predictors of creativity across neuroimaging modalities. This pattern aligns with proposals ascribing roles of working and long-term memory to problem-solving and imagination. Overall, our findings help to consolidate some, but not all, neural correlates of individual differences that have been discussed in the cognitive neuroimaging of creativity, yielding a subset that appear particularly promising for focused future investigation. •We tested pre-registered neurocognitive predictors of individual differences in creativity.•IFG volumes and IFG-IPL connections predicted creativity measures across imaging modalities.•Anterior cerebellum and parahippocampal gyrus were also multi-measure, multimodal predictors.•Our results support models in which creativity is promoted by ECN modulation of the DMN.
Defining the most probable location of the parahippocampal place area using cortex-based alignment and cross-validation
The parahippocampal place area (PPA) is a widely studied high-level visual region in the human brain involved in place and scene processing. The goal of the present study was to identify the most probable location of place-selective voxels in medial ventral temporal cortex. To achieve this goal, we first used cortex-based alignment (CBA) to create a probabilistic place-selective region of interest (ROI) from one group of 12 participants. We then tested how well this ROI could predict place selectivity in each hemisphere within a new group of 12 participants. Our results reveal that a probabilistic ROI (pROI) generated from one group of 12 participants accurately predicts the location and functional selectivity in individual brains from a new group of 12 participants, despite between subject variability in the exact location of place-selective voxels relative to the folding of parahippocampal cortex. Additionally, the prediction accuracy of our pROI is significantly higher than that achieved by volume-based Talairach alignment. Comparing the location of the pROI of the PPA relative to published data from over 500 participants, including data from the Human Connectome Project, shows a striking convergence of the predicted location of the PPA and the cortical location of voxels exhibiting the highest place selectivity across studies using various methods and stimuli. Specifically, the most predictive anatomical location of voxels exhibiting the highest place selectivity in medial ventral temporal cortex is the junction of the collateral and anterior lingual sulci. Methodologically, we make this pROI freely available (vpnl.stanford.edu/PlaceSelectivity), which provides a means to accurately identify a functional region from anatomical MRI data when fMRI data are not available (for example, in patient populations). Theoretically, we consider different anatomical and functional factors that may contribute to the consistent anatomical location of place selectivity relative to the folding of high-level visual cortex. •A probabilistic place ROI was created from cortex-based alignment in 24 participants•Cross-validation shows that this ROI predicts place selectivity in new participants•This ROI predicts voxels with peak place selectivity in >500 participants•The collateral/lingual sulcal junction is most predictive of place selectivity•We share this predictive ROI with the field (vpnl.stanford.edu/PlaceSelectivity)
Risk-taking in humans and the medial orbitofrontal cortex reward system
Risk-taking differs between humans, and is associated with the personality measures of impulsivity and sensation-seeking. To analyse the brain systems involved, self-report risk-taking, resting state functional connectivity, and related behavioral measures were analyzed in 18,740 participants of both sexes from the UK Biobank. Functional connectivities of the medial orbitofrontal cortex, ventromedial prefrontal cortex (VMPFC), and the parahippocampal areas were significantly higher in the risk-taking group (p < 0.001, FDR corrected). The risk-taking measure was validated in that it was significantly associated with alcohol drinking amount (r = 0.08, p = 5.1×10−28), cannabis use (r = 0.12, p = 6.0×10−66), and anxious feelings (r = -0.12, p = 7.6×−98). The functional connectivity findings were cross-validated in two independent datasets. The higher functional connectivity of the medial orbitofrontal cortex and VMPFC included higher connectivity with the anterior cingulate cortex, which provides a route for these reward-related regions to have a greater influence on action in risk-taking individuals. In conclusion, the medial orbitofrontal cortex, which is involved in reward value and pleasure, was found to be related to risk-taking, which is associated with impulsivity. An implication is that risk-taking is driven by specific orbitofrontal cortex reward systems, and is different for different rewards which are represented differently in the brains of different individuals. This is an advance in understanding the bases and mechanisms of risk-taking in humans, given that the orbitofrontal cortex, VMPFC and anterior cingulate cortex are highly developed in humans, and that risk-taking can be reported in humans.
Two cortical systems for memory-guided behaviour
Key Points The perirhinal cortex (PRC), parahippocampal cortex (PHC) and retrosplenial cortex (RSC) are crucial for memory in humans, so it is essential to understand the functions of these areas. The PHC and RSC exhibit patterns of anatomical and functional connectivity that are highly similar to one another and strikingly different from the PRC. The PRC is important for familiarity-based item recognition, associating features of objects and fine-grained perceptual or semantic discriminations. The PHC and RSC are important for recollection-based memories, memory for spatial and episodic context, scene perception, simulation of hypothetical events and certain aspects of spatial navigation and social cognition. Integrating this evidence, we propose a new framework in which the PRC, PHC and RSC are embedded in two extended networks that support different forms of memory-guided behaviour. The PRC is situated in an anterior temporal (AT) system that also includes the amygdala, ventral temporopolar cortex and lateral orbitofrontal cortex. This system may collectively support the assessment of the significance of specific entities. The PHC and RSC are situated in a posterior medial (PM) system that also includes the mammillary bodies, anterior thalamic nuclei, pre- and parasubiculum, posterior cingulate, precuneus and angular gyrus. This system may support the construction of situation models in support of memory, spatial navigation and social cognition. The AT and PM systems are differentially targeted by neurological disorders. For instance, semantic dementia is associated with disproportionate atrophy and dysfunction within the AT system relative to Alzheimer's disease, which disproportionately affects the PM system. The roles of the perirhinal, parahippocampal and retrosplenial cortices in memory are not well understood. Reviewing studies in rodents, monkeys and humans, Ranganath and Ritchey suggest that these areas are core components of two cortical networks that support different types of memory and different aspects of cognition. Although the perirhinal cortex (PRC), parahippocampal cortex (PHC) and retrosplenial cortex (RSC) have an essential role in memory, the precise functions of these areas are poorly understood. Here, we review the anatomical and functional characteristics of these areas based on studies in humans, monkeys and rats. Our Review suggests that the PRC and PHC–RSC are core components of two separate large-scale cortical networks that are dissociable by neuroanatomy, susceptibility to disease and function. These networks not only support different types of memory but also appear to support different aspects of cognition.
Hippocampal theta codes for distances in semantic and temporal spaces
The medial temporal lobe (MTL) is known to support episodic memory and spatial navigation, raising the possibility that its true function is to form “cognitive maps” of any kind of information. Studies in humans and animals support the idea that the hippocampal theta rhythm (4 to 8 Hz) is key to this mapping function, as it has been repeatedly observed during spatial navigation tasks. If episodic memory and spatial navigation are 2 sides of the same coin, we hypothesized that theta oscillations might reflect relations between explicitly nonspatial items, such as words. We asked 189 neurosurgical patients to perform a verbal free-recall task, of which 96 had indwelling electrodes placed in the MTL. Subjects were instructed to remember short lists of sequentially presented nouns. We found that hippocampal theta power and connectivity during item retrieval coded for semantic distances between words, as measured using word2vec-derived subspaces. Additionally, hippocampal theta indexed temporal distances between words after filtering lists on recall performance, to ensure adequate dynamic range in time. Theta effects were noted only for semantic subspaces of 1 dimension, indicating a substantial compression of the possible semantic feature space. These results lend further support to our growing confidence that the MTL forms cognitive maps of arbitrary representational spaces, helping to reconcile longstanding differences between the spatial and episodic memory literatures.
The occipital place area represents the local elements of scenes
Neuroimaging studies have identified three scene-selective regions in human cortex: parahippocampal place area (PPA), retrosplenial complex (RSC), and occipital place area (OPA). However, precisely what scene information each region represents is not clear, especially for the least studied, more posterior OPA. Here we hypothesized that OPA represents local elements of scenes within two independent, yet complementary scene descriptors: spatial boundary (i.e., the layout of external surfaces) and scene content (e.g., internal objects). If OPA processes the local elements of spatial boundary information, then it should respond to these local elements (e.g., walls) themselves, regardless of their spatial arrangement. Indeed, we found that OPA, but not PPA or RSC, responded similarly to images of intact rooms and these same rooms in which the surfaces were fractured and rearranged, disrupting the spatial boundary. Next, if OPA represents the local elements of scene content information, then it should respond more when more such local elements (e.g., furniture) are present. Indeed, we found that OPA, but not PPA or RSC, responded more to multiple than single pieces of furniture. Taken together, these findings reveal that OPA analyzes local scene elements – both in spatial boundary and scene content representation – while PPA and RSC represent global scene properties. •OPA responds to major surfaces (e.g., walls) regardless of their configuration.•PPA and RSC respond to the configuration of these surfaces.•OPA, not PPA or RSC, is sensitive to the number of pieces of furniture.•Findings suggest that OPA represents local scene elements (e.g., surfaces, furniture).•PPA and RSC may represent global scene properties like spatial boundary information.
Multiple parietal pathways are associated with rTMS-induced hippocampal network enhancement and episodic memory changes
Repetitive transcranial magnetic stimulation (rTMS) of the inferior parietal cortex (IPC) increases resting-state functional connectivity (rsFC) of the hippocampus with the precuneus and other posterior cortical areas and causes proportional improvement of episodic memory. The anatomical pathway(s) responsible for the propagation of these effects from the IPC is unknown and may not be direct. In order to assess the relative contributions of candidate pathways from the IPC to the MTL via the parahippocampal cortex and precuneus, to the effects of rTMS on rsFC and memory improvement, we used diffusion tensor imaging to measure the extent to which individual differences in fractional anisotropy (FA) in these pathways accounted for individual differences in response. FA in the IPC-parahippocampal pathway and several MTL pathways predicted changes in rsFC. FA in both parahippocampal and hippocampal pathways was related to changes in episodic, but not procedural, memory. These results implicate pathways to the MTL in the enhancing effect of parietal rTMS on hippocampal rsFC and memory.