Paracingulate sulcus morphology is associated with hallucinations in the human brain

Defining putative tertiary sulci in lateral prefrontal cortex in chimpanzees using human predictions

Similarities and differences in brain structure and function across species are of major interest in systems neuroscience, comparative biology, and brain mapping. Recently, increased emphasis has been placed on tertiary sulci, which are shallow indentations of the cerebral cortex that appear last in gestation, continue to develop after birth, and are largely either human or hominoid specific. While tertiary sulcal morphology in lateral prefrontal cortex (LPFC) has been linked to functional representations and cognition in humans, it is presently unknown if small and shallow LPFC sulci also exist in non-human hominoids. To fill this gap in knowledge, we leveraged two freely available multimodal datasets to address the following main question: Can small and shallow LPFC sulci be defined in chimpanzee cortical surfaces from human predictions of LPFC tertiary sulci? We found that 1-3 components of the posterior middle frontal sulcus (pmfs) in the posterior middle frontal gyrus are identifiable in nearly all chimpanzee hemispheres. In stark contrast to the consistency of the pmfs components, we could only identify components of the paraintermediate frontal sulcus (pimfs) in two chimpanzee hemispheres. Putative LPFC tertiary sulci were relatively smaller and shallower in chimpanzees compared to humans. In both species, two of the pmfs components were deeper in the right compared to the left hemisphere. As these results have direct implications for future studies interested in the functional and cognitive role of LPFC tertiary sulci, we share probabilistic predictions of the three pmfs components to guide the definitions of these sulci in future studies.

Emotion-related impulsivity is related to orbitofrontal cortical sulcation

BACKGROUND

Emotion-related impulsivity (ERI) describes the trait-like tendency toward poor self-control when experiencing strong emotions. ERI has been shown to be elevated across psychiatric disorders and predictive of the onset and worsening of psychiatric syndromes. Recent work has correlated ERI scores with the region-level neuroanatomical properties of the orbitofrontal cortex (OFC), but not posteromedial cortex (PMC). Informed by a growing body of research indicating that examining the morphology of specific cortical folds (sulci) can produce unique insights into behavioral outcomes, the present study modeled the association between ERI and the morphology of sulci within OFC and PMC, which is a finer scale than previously conducted.

METHODS

Analyses were conducted in a transdiagnostic sample of 118 adult individuals with a broad range of psychiatric syndromes. First, we manually defined over 4,000 sulci across 236 cerebral hemispheres. Second, we implemented a model-based LASSO regression to relate OFC sulcal morphology to ERI. Third, we tested whether effects were specific to OFC sulci, sulcal depth, and ERI (as compared to PMC sulci, sulcal gray matter thickness, and non-emotion-related impulsivity).

RESULTS

The LASSO regression revealed bilateral associations of ERI with the depths of eight OFC sulci. These effects were strongest for OFC sulci, sulcal depth, and ERI in comparison to PMC sulci, sulcal gray matter thickness, and non-emotion-related impulsivity. In addition, we identified a new transverse component of the olfactory sulcus in every hemisphere that is dissociable from the longitudinal component based on anatomical features and correlation with behavior, which could serve as a new transdiagnostic biomarker.

CONCLUSIONS

The results of this data-driven investigation provide greater neuroanatomical and neurodevelopmental specificity on how OFC is related to ERI. As such, findings link neuroanatomical characteristics to a trait that is highly predictive of psychopathology.

Variable Presence of an Evolutionarily New Brain Structure is Related to Trait Impulsivity

Background

Impulsivity is a multidimensional construct reflecting poor constraint over one's behaviors. Clinical psychology research identifies separable impulsivity dimensions that are each unique transdiagnostic indicators for psychopathology. Yet, despite this apparent clinical importance, the shared and unique neuroanatomical correlates of these factors remain largely unknown. Concomitantly, neuroimaging research identifies variably present human brain structures implicated in cognition and disorder: the folds (sulci) of the cerebral cortex located in the latest developing and most evolutionarily expanded hominoid-specific association cortices.

Methods

We tethered these two fields to test whether variability in one such structure in anterior cingulate cortex (ACC)-the paracingulate sulcus (PCGS)-was related to individual differences in trait impulsivity. 120 adult participants with internalizing or externalizing psychopathology completed a magnetic resonance imaging scan and the Three-Factor Impulsivity Index. Using precision imaging techniques, we manually identified the PCGS, when present, and acquired quantitative folding metrics (PCGS length and ACC local gyrification index).

Results

Neuroanatomical-behavioral analyses revealed that participants with leftward or symmetrical PCGS patterns had greater severity of Lack of Follow Through (LFT)-which captures inattention and lack of perseverance-than those with rightward asymmetry. Neuroanatomical-functional analyses identified that the PCGS co-localized with a focal locus found in a neuroimaging meta-analysis on a feature underlying LFT. Both quantitative folding metrics did not relate to any impulsivity dimension.

Conclusions

This study advances understanding of the neuroanatomical correlates of impulsivity and establishes the notion that the topographical organization of distinct, hominoid-specific cortical expanses underlie separable impulsivity dimensions with robust, transdiagnostic implications for psychopathology.

Structural and functional connectivity associations with anterior cingulate sulcal variability

Sulcation of the anterior cingulate may be defined by presence of a paracingulate sulcus, a tertiary sulcus developing during the third gestational trimester with implications on cognitive function and disease. In this cross-sectional study we examine task-free resting state functional connectivity and diffusion-weighted tract segmentation data from a cohort of healthy adults (< 60-year-old, n = 129), exploring the impact of ipsilateral paracingulate sulcal presence on structural and functional connectivity. Presence of a left paracingulate sulcus was associated with reduced fractional anisotropy in the left cingulum bundle and the left peri-genual and dorsal bundle segments, suggesting reduced structural organisational coherence in these tracts. This association was not observed in the offsite temporal cingulum bundle segment. Left paracingulate sulcal presence was associated with increased left peri-genual radial diffusivity and tract volume possibly suggesting increased U-fibre density in this region. Greater network dispersity was identified in individuals with an absent left paracingulate sulcus by presence of a significant, predominantly intraregional, frontal component of resting state functional connectivity which was not present in individuals with a present left paracingulate sulcus. Seed-based functional connectivity in pre-defined networks was not associated with paracingulate sulcal presence. These results identify a novel association between sulcation and structural connectivity in a healthy adult population with implications for conditions where this variation is of interest. Presence of a left paracingulate sulcus appears to alter local structural and functional connectivity, possibly as a result of the presence of a local network reliant on short association fibres.

Unique longitudinal contributions of sulcal interruptions to reading acquisition in children

A growing body of literature indicates strong associations between indentations of the cerebral cortex (i.e., sulci) and individual differences in cognitive performance. Interruptions, or gaps, of sulci (historically known as pli de passage) are particularly intriguing as previous work suggests that these interruptions have a causal effect on cognitive development. Here, we tested how the presence and morphology of sulcal interruptions in the left posterior occipitotemporal sulcus (pOTS) longitudinally impact the development of a culturally-acquired skill: reading. Forty-three children were successfully followed from age 5 in kindergarten, at the onset of literacy instruction, to ages 7 and 8 with assessments of cognitive, pre-literacy, and literacy skills, as well as MRI anatomical scans at ages 5 and 8. Crucially, we demonstrate that the presence of a left pOTS gap at 5 years is a specific and robust longitudinal predictor of better future reading skills in children, with large observed benefits on reading behavior ranging from letter knowledge to reading comprehension. The effect of left pOTS interruptions on reading acquisition accumulated through time, and was larger than the impact of benchmark cognitive and familial predictors of reading ability and disability. Finally, we show that increased local U-fiber white matter connectivity associated with such sulcal interruptions possibly underlie these behavioral benefits, by providing a computational advantage. To our knowledge, this is the first quantitative evidence supporting a potential integrative gray-white matter mechanism underlying the cognitive benefits of macro-anatomical differences in sulcal morphology related to longitudinal improvements in a culturally-acquired skill.

Single-cell morphodynamical trajectories enable prediction of gene expression accompanying cell state change

Extracellular signals induce changes to molecular programs that modulate multiple cellular phenotypes, including proliferation, motility, and differentiation status. The connection between dynamically adapting phenotypic states and the molecular programs that define them is not well understood. Here we develop data-driven models of single-cell phenotypic responses to extracellular stimuli by linking gene transcription levels to "morphodynamics" - changes in cell morphology and motility observable in time-lapse image data. We adopt a dynamics-first view of cell state by grouping single-cell trajectories into states with shared morphodynamic responses. The single-cell trajectories enable development of a first-of-its-kind computational approach to map live-cell dynamics to snapshot gene transcript levels, which we term MMIST, Molecular and Morphodynamics-Integrated Single-cell Trajectories. The key conceptual advance of MMIST is that cell behavior can be quantified based on dynamically defined states and that extracellular signals alter the overall distribution of cell states by altering rates of switching between states. We find a cell state landscape that is bound by epithelial and mesenchymal endpoints, with distinct sequences of epithelial to mesenchymal transition (EMT) and mesenchymal to epithelial transition (MET) intermediates. The analysis yields predictions for gene expression changes consistent with curated EMT gene sets and provides a prediction of thousands of RNA transcripts through extracellular signal-induced EMT and MET with near-continuous time resolution. The MMIST framework leverages true single-cell dynamical behavior to generate molecular-level omics inferences and is broadly applicable to other biological domains, time-lapse imaging approaches and molecular snapshot data.

Updating the sulcal landscape of the human lateral parieto-occipital junction provides anatomical, functional, and cognitive insights

Recent work has uncovered relationships between evolutionarily new small and shallow cerebral indentations, or sulci, and human behavior. Yet, this relationship remains unexplored in the lateral parietal cortex (LPC) and the lateral parieto-occipital junction (LPOJ). After defining thousands of sulci in a young adult cohort, we revised the previous LPC/LPOJ sulcal landscape to include four previously overlooked, small, shallow, and variable sulci. One of these sulci (ventral supralateral occipital sulcus, slocs-v) is present in nearly every hemisphere and is morphologically, architecturally, and functionally dissociable from neighboring sulci. A data-driven, model-based approach, relating sulcal depth to behavior further revealed that the morphology of only a subset of LPC/LPOJ sulci, including the slocs-v, is related to performance on a spatial orientation task. Our findings build on classic neuroanatomical theories and identify new neuroanatomical targets for future "precision imaging" studies exploring the relationship among brain structure, brain function, and cognitive abilities in individual participants.

Defining Overlooked Structures Reveals New Associations between the Cortex and Cognition in Aging and Alzheimer's Disease

Recent work suggests that indentations of the cerebral cortex, or sulci, may be uniquely vulnerable to atrophy in aging and Alzheimer's disease (AD) and that the posteromedial cortex (PMC) is particularly vulnerable to atrophy and pathology accumulation. However, these studies did not consider small, shallow, and variable tertiary sulci that are located in association cortices and are often associated with human-specific aspects of cognition. Here, we manually defined 4,362 PMC sulci in 432 hemispheres in 216 human participants (50.5% female) and found that these smaller putative tertiary sulci showed more age- and AD-related thinning than larger, more consistent sulci, with the strongest effects for two newly uncovered sulci. A model-based approach relating sulcal morphology to cognition identified that a subset of these sulci was most associated with memory and executive function scores in older adults. These findings lend support to the retrogenesis hypothesis linking brain development and aging and provide new neuroanatomical targets for future studies of aging and AD.

Sulcal variability in anterior lateral prefrontal cortex contributes to variability in reasoning performance among young adults

Identifying structure-function correspondences is a major goal among biologists, cognitive neuroscientists, and brain mappers. Recent studies have identified relationships between performance on cognitive tasks and the presence or absence of small, shallow indentations, or sulci, of the human brain. Building on the previous finding that the presence of the ventral para-intermediate frontal sulcus (pimfs-v) in the left anterior lateral prefrontal cortex (aLPFC) was related to reasoning task performance in children and adolescents, we tested whether this relationship extended to a different sample, age group, and reasoning task. As predicted, the presence of this aLPFC sulcus was also associated with higher reasoning scores in young adults (ages 22-36). These findings have not only direct developmental, but also evolutionary relevance-as recent work shows that the pimfs-v is exceedingly rare in chimpanzees. Thus, the pimfs-v is a key developmental, cognitive, and evolutionarily relevant feature that should be considered in future studies examining how the complex relationships among multiscale anatomical and functional features of the brain give rise to abstract thought.

Emotion-related impulsivity is related to orbitofrontal cortical sulcation

Background

Emotion-related impulsivity (ERI) describes the trait-like tendency toward poor self-control when experiencing strong emotions. ERI has been shown to be elevated across psychiatric disorders and predictive of the onset and worsening of psychiatric syndromes. Recent work has correlated ERI scores with the neuroanatomy of the orbitofrontal cortex (OFC). Informed by a growing body of research indicating that the morphology of cortical folds (sulci) can produce insights into behavioral outcomes, the present study modeled the association between ERI and the sulcal morphology of OFC at a finer scale than previously conducted.

Methods

Analyses were conducted in a transdiagnostic sample of 118 individuals with a broad range of psychiatric syndromes. We first manually defined over 2000 sulci across the 118 participants. We then implemented a model-based LASSO regression to relate OFC sulcal morphology to ERI and test whether effects were specific to ERI as compared to non-emotion-related impulsivity.

Results

The LASSO regression revealed bilateral associations of ERI with the depth of eight OFC sulci. These effects were specific to ERI and were not observed in non-emotion-related impulsivity. In addition, we identified a new transverse component of the olfactory sulcus in every hemisphere that is dissociable from the longitudinal component based on anatomical features and correlation with behavior, which could serve as a new transdiagnostic biomarker.

Conclusions

The results of this data-driven investigation provide greater neuroanatomical and neurodevelopmental specificity on how OFC is related to ERI. As such, findings link neuroanatomical characteristics to a trait that is highly predictive of psychopathology.

Structural and functional connectivity associations with anterior cingulate sulcal variability

Background

Sulcation of the anterior cingulate may be defined by presence of a paracingulate sulcus, a tertiary sulcus developing during the third gestational trimester with implications on cognitive function and disease.

Methods

In this retrospective analysis we examine task-free resting state functional connectivity and diffusion-weighted tract segmentation data from a cohort of healthy adults (< 60-year-old, n = 129), exploring the impact of ipsilateral paracingulate sulcal presence on structural and functional connectivity.

Results

Presence of a left paracingulate sulcus was associated with reduced fractional anisotropy in the left cingulum (P = 0.02) bundle and the peri-genual (P = 0.002) and dorsal (P = 0.03) but not the temporal cingulum bundle segments. Left paracingulate sulcal presence was associated with increased left peri-genual radial diffusivity (P = 0.003) and tract volume (P = 0.012). A significant, predominantly intraregional frontal component of altered resting state functional connectivity was identified in individuals possessing a left PCS (P = 0.01). Seed-based functional connectivity in pre-defined networks was not associated with paracingulate sulcal presence.

Conclusion

These results identify a novel association between neurodevelopmentally derived sulcation and altered structural connectivity in a healthy adult population with implications for conditions where this variation is of interest. Furthermore, they provide evidence of a link between the structural and functional connectivity of the brain in the presence of a paracingulate sulcus which may be mediated by a highly connected local functional network reliant on short association fibres.

Neuroanatomical and Functional Dissociations between Variably Present Anterior Lateral Prefrontal Sulci

The lateral prefrontal cortex (LPFC) is an evolutionarily expanded region in humans that is critical for numerous complex functions, many of which are largely hominoid specific. Although recent work shows that the presence or absence of specific sulci in anterior LPFC is associated with cognitive performance across age groups, it is unknown whether the presence of these structures relates to individual differences in the functional organization of LPFC. To fill this gap in knowledge, we leveraged multimodal neuroimaging data from two samples encompassing 82 young adult humans (aged 22-36 years) and show that the dorsal and ventral components of the paraintermediate frontal sulcus, or pimfs, present distinct morphological (surface area), architectural (thickness and myelination), and functional (resting-state connectivity networks) properties. We further contextualize the pimfs components within classic and modern cortical parcellations. Taken together, the dorsal and ventral pimfs components mark transitions in LPFC anatomy and function, across metrics and parcellations. These results emphasize that the pimfs is a critical structure to consider when examining individual differences in the anatomical and functional organization of LPFC and suggest that future individual-level parcellations could benefit from incorporating sulcal anatomy when delineating LPFC cortical regions.

Anterior cingulate sulcation is associated with onset and survival in frontotemporal dementia

Frontotemporal dementia is the second most common form of early onset dementia (<65 years). Despite this, there are few known disease-modifying factors. The anterior cingulate is a focal point of pathology in behavioural variant frontotemporal dementia. Sulcation of the anterior cingulate is denoted by the presence of a paracingulate sulcus, a tertiary sulcus developing, where present during the third gestational trimester and remaining stable throughout life. This study aims to examine the impact of right paracingulate sulcal presence on the expression and prognosis of behavioural variant frontotemporal dementia. This retrospective analysis drew its population from two clinical samples recruited from memory clinics at university hospitals in the USA and The Netherlands. Individuals with sporadic behavioural variant frontotemporal dementia were enrolled between 2000 and 2022 and followed up for an average of 7.71 years. T1-MRI data were evaluated for hemispheric paracingulate sulcal presence in accordance with an established protocol by two blinded raters. Outcome measures included age at onset, survival, cortical thickness and Frontotemporal Lobar Degeneration-modified Clinical Dementia Rating determined clinical disease progression. The study population consisted of 186 individuals with sporadic behavioural variant frontotemporal dementia (113 males and 73 females), mean age 63.28 years (SD 8.32). The mean age at onset was 2.44 years later in individuals possessing a right paracingulate sulcus [60.2 years (8.54)] versus individuals who did not [57.76 (8.05)], 95% confidence interval > 0.41, P = 0.02. Education was not associated with age at onset (β = -0.05, P = 0.75). The presence of a right paracingulate sulcus was associated with an 83% increased risk of death per year after age at onset (hazard ratio 1.83, confidence interval [1.09-3.07], P < 0.02), whilst the mean age at death was similar for individuals with a present and absent right paracingulate sulcus (P = 0.7). Right paracingulate sulcal presence was not associated with baseline cortical thickness. Right paracingulate sulcal presence is associated with disease expression and survival in sporadic behavioural variant frontotemporal dementia. Findings provide evidence of neurodevelopmental brain reserve in behavioural variant frontotemporal dementia that may be important in the design of trials for future therapeutic approaches.

GABAA receptor availability relates to emotion-induced BOLD responses in the medial prefrontal cortex: simultaneous fMRI/PET with [11C]flumazenil

Introduction

The fMRI BOLD response to emotional stimuli highlighting the role of the medial prefrontal cortex (MPFC) has been thoroughly investigated. Recently, the relationship between emotion processing and GABA levels has been studied using MPFC proton magnetic resonance spectroscopy (1H-MRS). However, the role of GABAA receptors in the MPFC during emotion processing remains unexplored.

Methods

Using [11C]flumazenil PET, we investigated the relationship between the binding potential of GABAA receptors and emotion processing as measured using simultaneous fMRI BOLD. We hypothesized a correlation between the percent signal change in the BOLD signal and the binding potential of GABAA receptors in the MPFC. In a combined simultaneous fMRI and [11C]flumazenil-PET study, we analyzed the data from 15 healthy subjects using visual emotional stimuli. Our task comprised two types of emotional processing: passive viewing and appraisal. Following the administration of a bolus plus infusion protocol, PET and fMRI data were simultaneously acquired in a hybrid 3 T MR-BrainPET.

Results

We found a differential correlation of BOLD percent signal change with [11C]flumazenil binding potential in the MPFC. Specifically, [11C]flumazenil binding potential in the ventromedial prefrontal cortex (vMPFC) correlated with passive viewing of emotionally valenced pictures. In contrast, the [11C]flumazenil binding potential and the BOLD signal induced by picture appraisal did show a correlation in the paracingulate gyrus.

Conclusion

Our data deliver first evidence for a relationship between MPFC GABAA receptors and emotion processing in the same region. Moreover, we observed that GABAA receptors appear to play different roles in emotion processing in the vMPFC (passive viewing) and paracingulate gyrus (appraisal).

The neural signature of reality-monitoring: A meta-analysis of functional neuroimaging studies

Distinguishing imagination and thoughts from information we perceived from the environment, a process called reality-monitoring, is important in everyday situations. Although reality monitoring seems to overlap with the concept of self-monitoring, which allows one to distinguish self-generated actions or thoughts from those generated by others, the two concepts remain largely separate cognitive domains and their common brain substrates have received little attention. We investigated the brain regions involved in these two cognitive processes and explored the common brain regions they share. To do this, we conducted two separate coordinate-based meta-analyses of functional magnetic resonance imaging studies assessing the brain regions involved in reality- and self-monitoring. Few brain regions survived threshold-free cluster enhancement family-wise multiple comparison correction (p < .05), likely owing to the small number of studies identified. Using uncorrected statistical thresholds recommended by Signed Differential Mapping with Permutation of Subject Images, the meta-analysis of reality-monitoring studies (k = 9 studies including 172 healthy subjects) revealed clusters in the lobule VI of the cerebellum, the right anterior medial prefrontal cortex and anterior thalamic projections. The meta-analysis of self-monitoring studies (k = 12 studies including 192 healthy subjects) highlighted the involvement of a set of brain regions including the lobule VI of the left cerebellum and fronto-temporo-parietal regions. We showed with a conjunction analysis that the lobule VI of the cerebellum was consistently engaged in both reality- and self-monitoring. The current findings offer new insights into the common brain regions underlying reality-monitoring and self-monitoring, and suggest that the neural signature of the self that may occur during self-production should persist in memories.

Defining overlooked structures reveals new associations between cortex and cognition in aging and Alzheimer's disease

Recent work suggests that indentations of the cerebral cortex, or sulci, may be uniquely vulnerable to atrophy in aging and Alzheimer's disease (AD) and that posteromedial cortex (PMC) is particularly vulnerable to atrophy and pathology accumulation. However, these studies did not consider small, shallow, and variable tertiary sulci that are located in association cortices and are often associated with human-specific aspects of cognition. Here, we first manually defined 4,362 PMC sulci in 432 hemispheres in 216 participants. Tertiary sulci showed more age- and AD-related thinning than non-tertiary sulci, with the strongest effects for two newly uncovered tertiary sulci. A model-based approach relating sulcal morphology to cognition identified that a subset of these sulci were most associated with memory and executive function scores in older adults. These findings support the retrogenesis hypothesis linking brain development and aging, and provide new neuroanatomical targets for future studies of aging and AD.

Sulcal morphology of posteromedial cortex substantially differs between humans and chimpanzees

Recent studies identify a surprising coupling between evolutionarily new sulci and the functional organization of human posteromedial cortex (PMC). Yet, no study has compared this modern PMC sulcal patterning between humans and non-human hominoids. To fill this gap in knowledge, we first manually defined over 2500 PMC sulci in 120 chimpanzee (Pan Troglodytes) hemispheres and 144 human hemispheres. We uncovered four new sulci, and quantitatively identified species differences in sulcal incidence, depth, and surface area. Interestingly, some sulci are more common in humans and others, in chimpanzees. Further, we found that the prominent marginal ramus of the cingulate sulcus differs significantly between species. Contrary to classic observations, the present results reveal that the surface anatomy of PMC substantially differs between humans and chimpanzees-findings which lay a foundation for better understanding the evolution of neuroanatomical-functional and neuroanatomical-behavioral relationships in this highly expanded region of the human cerebral cortex.

Neuroanatomical and functional dissociations between variably present anterior lateral prefrontal sulci

The lateral prefrontal cortex (LPFC) is an evolutionarily expanded region in humans that is critical for numerous complex functions, many of which are largely hominoid-specific. While recent work shows that the presence or absence of specific sulci in anterior LPFC is associated with cognitive performance across age groups, it is unknown whether the presence of these structures relates to individual differences in the functional organization of LPFC. To fill this gap in knowledge, we leveraged multimodal neuroimaging data from 72 young adult humans aged 22-36 and show that dorsal and ventral components of the paraintermediate frontal sulcus (pimfs) present distinct morphological (surface area), architectural (thickness and myelination), and functional (resting-state connectivity networks) properties. We further contextualize the pimfs components within classic and modern cortical parcellations. Taken together, the dorsal and ventral pimfs components mark transitions in anatomy and function in LPFC, across metrics and parcellations. These results emphasize that the pimfs is a critical structure to consider when examining individual differences in the anatomical and functional organization of LPFC and highlight the importance of considering individual anatomy when investigating structural and functional features of the cortex.

Studying Healthy Psychosislike Experiences to Improve Illness Prediction

Importance

Distinguishing delusions and hallucinations from unusual beliefs and experiences has proven challenging.

Observations

The advent of neural network and generative modeling approaches to big data offers a challenge and an opportunity; healthy individuals with unusual beliefs and experiences who are not ill may raise false alarms and serve as adversarial examples to such networks.

Conclusions and Relevance

Explicitly training predictive models with adversarial examples should provide clearer focus on the features most relevant to casehood, which will empower clinical research and ultimately diagnosis and treatment.

Anterior cingulate sulcation is associated with onset and survival in frontotemporal dementia

Background

Frontotemporal dementia is the second most common form of early onset dementia (< 65 years). Despite this there are few known disease modifying factors. The anterior cingulate is a focal point of pathology in behavioural variant frontotemporal dementia. Sulcation of the anterior cingulate is denoted by the presence of a paracingulate sulcus, a tertiary sulcus developing, where present during the third gestational trimester and remaining stable throughout life. This study aims to examine the impact of right paracingulate sulcal presence on the expression and prognosis of behavioural variant Frontotemporal Dementia.

Methods

This retrospective analysis drew it's population from two clinical samples recruited from memory clinics at University Hospitals in The United States of America and The Netherlands. Individuals with sporadic behavioural variant Frontotemporal Dementia were enrolled between 2004 and 2022 and followed up for an average of 7.71 years. T1-MRI data were evaluated for hemispheric paracingulate sulcal presence in accordance with an established protocol by two blinded raters. Outcome measures included age at onset, survival, cortical thickness, and Frontotemporal Lobar Degeneration-modified Clinical Dementia Rating determined clinical disease progression.

Results

The study population consisted of 186 individuals with sporadic behavioural variant Frontotemporal Dementia, (113 males and 73 females) mean age 63.28 years (SD 8.32). The mean age at onset was 2.44 years later in individuals possessing a right paracingulate sulcus (60.2 years (SD 8.54)) versus individuals who did not (57.76 (8.05)), 95% CI >0.41, P = 0.02. Education was not associated with age at onset (β = -0.05, P =0.75). Presence of a right paracingulate sulcus was associated with a 119% increased risk of death per year after age at onset (HR 2.19, CI [1.21 - 3.96], P <0.01), whilst the mean age at death was similar for individuals with a present and absent right paracingulate sulcus ( P = 0.7). Right paracingulate sulcal presence was not associated with baseline cortical thickness.

Conclusion

Right paracingulate sulcal presence is associated with disease expression and survival in sporadic behavioural variant Frontotemporal Dementia. Findings provide evidence of neurodevelopmental brain reserve in behavioural variant Frontotemporal Dementia which may be important in the design of trials for future therapeutic approaches.

Neurophysiological mechanisms of error monitoring in human and non-human primates

Performance monitoring is an important executive function that allows us to gain insight into our own behaviour. This remarkable ability relies on the frontal cortex, and its impairment is an aspect of many psychiatric diseases. In recent years, recordings from the macaque and human medial frontal cortex have offered a detailed understanding of the neurophysiological substrate that underlies performance monitoring. Here we review the discovery of single-neuron correlates of error monitoring, a key aspect of performance monitoring, in both species. These neurons are the generators of the error-related negativity, which is a non-invasive biomarker that indexes error detection. We evaluate a set of tasks that allows the synergistic elucidation of the mechanisms of cognitive control across the two species, consider differences in brain anatomy and testing conditions across species, and describe the clinical relevance of these findings for understanding psychopathology. Last, we integrate the body of experimental facts into a theoretical framework that offers a new perspective on how error signals are computed in both species and makes novel, testable predictions.

Hominoid-specific sulcal variability is related to face perception ability

The relationship among brain structure, brain function, and behavior is of major interest in neuroscience, evolutionary biology, and psychology. This relationship is especially intriguing when considering hominoid-specific brain structures because they cannot be studied in widely examined models in neuroscience such as mice, marmosets, and macaques. The fusiform gyrus (FG) is a hominoid-specific structure critical for face processing that is abnormal in individuals with developmental prosopagnosia (DPs)-individuals who have severe deficits recognizing the faces of familiar people in the absence of brain damage. While previous studies have found anatomical and functional differences in the FG between DPs and NTs, no study has examined the shallow tertiary sulcus (mid-fusiform sulcus, MFS) within the FG that is a microanatomical, macroanatomical, and functional landmark in humans, as well as was recently shown to be present in non-human hominoids. Here, we implemented pre-registered analyses of neuroanatomy and face perception in NTs and DPs. Results show that the MFS was shorter in DPs than NTs. Furthermore, individual differences in MFS length in the right, but not left, hemisphere predicted individual differences in face perception. These results support theories linking brain structure and function to perception, as well as indicate that individual differences in MFS length can predict individual differences in face processing. Finally, these findings add to growing evidence supporting a relationship between morphological variability of late developing, tertiary sulci and individual differences in cognition.

Sulcal depth in prefrontal cortex: a novel predictor of working memory performance

The neuroanatomical changes that underpin cognitive development are of major interest in neuroscience. Of the many aspects of neuroanatomy to consider, tertiary sulci are particularly attractive as they emerge last in gestation, show a protracted development after birth, and are either human- or hominoid-specific. Thus, they are ideal targets for exploring morphological-cognitive relationships with cognitive skills that also show protracted development such as working memory (WM). Yet, the relationship between sulcal morphology and WM is unknown-either in development or more generally. To fill this gap, we adopted a data-driven approach with cross-validation to examine the relationship between sulcal depth in lateral prefrontal cortex (LPFC) and verbal WM in 60 children and adolescents between ages 6 and 18. These analyses identified 9 left, and no right, LPFC sulci (of which 7 were tertiary) whose depth predicted verbal WM performance above and beyond the effect of age. Most of these sulci are located within and around contours of previously proposed functional parcellations of LPFC. This sulcal depth model outperformed models with age or cortical thickness. Together, these findings build empirical support for a classic theory that tertiary sulci serve as landmarks in association cortices that contribute to late-maturing human cognitive abilities.

Sulcal morphology of posteromedial cortex substantially differs between humans and chimpanzees

Recent studies identify a surprising coupling between evolutionarily new sulci and the functional organization of human posteromedial cortex (PMC). Yet, no study has compared this modern PMC sulcal patterning between humans and non-human hominoids. To fill this gap in knowledge, we first manually defined 918 sulci in 120 chimpanzee ( Pan Troglodytes ) hemispheres and 1619 sulci in 144 human hemispheres. We uncovered four new PMC sulci, and quantitatively identified species differences in incidence, depth, and surface area. Interestingly, some PMC sulci are more common in humans and others, in chimpanzees. Further, we found that the prominent marginal ramus of the cingulate sulcus differs significantly between species. Contrary to classic observations, the present results reveal that the surface anatomy of PMC substantially differs between humans and chimpanzees â€" findings which lay a foundation for better understanding the evolution of neuroanatomical-functional and neuroanatomical-behavioral relationships in this highly expanded region of the human cerebral cortex.

Influence of accessory sulci of the frontoparietal operculum on gray matter quantification

Introduction: The perisylvian region is the cortical core of language and speech. Several accessory sulci have been described in this area, whose presence could modify the results of the automatic quantification of gray matter by popularly used software. This study aimed to assess the expression of accessory sulci in the frontoparietal operculum (FPO) and to evaluate their influence on the gray matter volume estimated by an automatic parcellation of cortical gyri and sulci. Methods: Brain MRI scans of 100 healthy adult volunteers were visually analyzed. The existence of the triangular and diagonal sulci, and the number of accessory sulci in the frontoparietal operculum, were assessed on T1 images. Also, the gray matter volume of gyri and sulci was quantified by an automatized parcellation method. Interhemispheric differences in accessory sulci were evaluated with Chi-square and Wilcoxon paired tests. The effects of the hemisphere, sex, age, total intracranial volume, and accessory sulci on morphometric variables were assessed by linear models. Results: These sulci were found in more than half of the subjects, mostly in the left hemisphere, and showed a significant effect on the gray matter content of the FPO. In particular, the volume of the inferior frontal sulcus, pars opercularis of the inferior frontal gyrus, horizontal ramus of the lateral sulcus, angular gyrus, and postcentral gyrus showed a significant influence on the presence of accessory sulci. Discussion: The prevalence of tertiary sulci in the FPO is high, although their meaning is not yet known. Therefore, they should be considered to reduce the risk of misclassifications of normal variation.

Correlates of poor insight: A comparative fMRI and sMRI study in obsessive-compulsive disorder and schizo-obsessive disorder

BACKGROUND

Despite the several researches on the correlates of insight in psychosis, less is known regarding the specificity of disease diagnosis on the relationship between insight and the correlates. The current study sought to explore the effects of insight and disease diagnosis on those in patients with obsessive-compulsive disorder (OCD) and patients with schizo-obsessive disorder (SOD).

METHODS

We evaluated clinical symptoms and neurocognitions among 111 patients (including 41 OCD with good insight, 40 OCD with poor insight, 14 SOD with good insight and 16 SOD with poor insight. Gray matter volume and spontaneous neural activity were also examined by analyzing the voxel-based morphometry and amplitude of low frequency fluctuation (ALFF), respectively.

RESULTS

Interactive effects of insight and diagnosis was found on working memory and the gray matter volume in right superior and middle temporal gyrus. Main effect of insight was found on working and visual memory, compulsion and obsession, and ALFF in right middle and superior occipital cortex. Main effect of diagnosis was found on severity of compulsion, relative verbal IQ, executive function, verbal and visual memory, working memory and ALFF in precuneus, medial superior frontal gyrus, anterior cingulate and paracingulate gyri, and inferior parietal, postcentral gyrus, paracentral lobule.

CONCLUSIONS

As a common feature in mental disorders, insight has its own special influence on neurocognition and possible structural/functional alterations in brain, and the influence is partly dependent of disease diagnosis.

Structural brain abnormalities in schizophrenia patients with a history and presence of auditory verbal hallucination

Although many studies have demonstrated structural brain abnormalities associated with auditory verbal hallucinations (AVH) in schizophrenia, the results remain inconsistent because of the small sample sizes and the reliability of clinical interviews. We compared brain morphometries in 204 participants, including 58 schizophrenia patients with a history of AVH (AVH + ), 29 without a history of AVH (AVH-), and 117 healthy controls (HCs) based on a detailed inspection of medical records. We further divided the AVH+ group into 37 patients with and 21 patients without hallucinations at the time of the MRI scans (AVH++ and AVH+-, respectively) via clinical interviews to explore the morphological differences according to the persistence of AVH. The AVH + group had a smaller surface area in the left caudal middle frontal gyrus (F = 7.28, FDR-corrected p = 0.0008) and precentral gyrus (F = 7.68, FDR-corrected p = 0.0006) compared to the AVH- group. The AVH+ patients had a smaller surface area in the left insula (F = 7.06, FDR-corrected p = 0.001) and a smaller subcortical volume in the bilateral hippocampus (right: F = 13.34, FDR-corrected p = 0.00003; left: F = 6.80, FDR-corrected p = 0.001) compared to the HC group. Of these significantly altered areas, the AVH++ group showed significantly smaller bilateral hippocampal volumes compared to the AVH+- group, and a smaller surface area in the left precentral gyrus and caudal middle frontal gyrus compared to the AVH- group. Our findings highlighted the distinct pattern of structural alteration between the history and presence of AVH in schizophrenia, and the importance of integrating multiple criteria to elucidate the neuroanatomical mechanisms.

Morphology of Anterior Cingulate Cortex and Its Relation to Schizophrenia

Cortical folding of the anterior cingulate cortex (ACC), particularly the cingulate (CS) and the paracingulate (PCS) sulci, represents a neurodevelopmental marker. Deviations in in utero development in schizophrenia can be traced using CS and PCS morphometry. In the present study, we measured the length of CS, PCS, and their segments on T1 MRI scans in 93 patients with first- episode schizophrenia and 42 healthy controls. Besides the length, the frequency and the left-right asymmetry of CS/PCS were compared in patients and controls. Distribution of the CS and PCS morphotypes in patients was different from controls. Parcellated sulcal pattern CS3a in the left hemisphere was longer in patients (53.8 ± 25.7 mm vs. 32.7 ± 19.4 mm in controls, p < 0.05), while in CS3c it was reversed—longer in controls (52.5 ± 22.5 mm as opposed to 36.2 ± 12.9 mm, n.s. in patients). Non parcellated PCS in the right hemisphere were longer in patients compared to controls (19.4 ± 10.2 mm vs. 12.1 ± 12.4 mm, p < 0.001). Therefore, concurrent presence of PCS1 and CS1 in the left hemisphere and to some extent in the right hemisphere may be suggestive of a higher probability of schizophrenia.

Uncovering a tripartite landmark in posterior cingulate cortex

Understanding brain structure-function relationships, and their development and evolution, is central to neuroscience research. Here, we show that morphological differences in posterior cingulate cortex (PCC), a hub of functional brain networks, predict individual differences in macroanatomical, microstructural, and functional features of PCC. Manually labeling 4511 sulci in 572 hemispheres, we found a shallow cortical indentation (termed the inframarginal sulcus; ifrms) within PCC that is absent from neuroanatomical atlases yet colocalized with a focal, functional region of the lateral frontoparietal network implicated in cognitive control. This structural-functional coupling generalized to meta-analyses consisting of hundreds of studies and thousands of participants. Additional morphological analyses showed that unique properties of the ifrms differ across the life span and between hominoid species. These findings support a classic theory that shallow, tertiary sulci serve as landmarks in association cortices. They also beg the question: How many other cortical indentations have we missed?

Unfolding the evolution of human cognition

Recent findings spanning fields, from braincases in paleoneurobiology to invivo measurements in cognitive neuroscience, provide insights into the evolution of cognition. Here, we integrate these findings and propose that studying small, evolutionarily new cortical structures has significant implications for identifying new links between neuroanatomical substrates and human-specific aspects of cognition.

Clinical correlates of regional gray matter volumes in schizophrenia: A structural magnetic resonance imaging study

OBJECTIVES

The objective of this study is to investigate the correlation between the regional gray matter volumes and length of Para Cingulate Sulcus (PCS) with the clinical profile of patients with schizophrenia.

MATERIALS AND METHODS

In this hospital-based, cross-sectional study, thirty consecutive in-patients diagnosed with schizophrenia and equal number of healthy volunteers matched for age- and sex- were recruited as controls. Detailed clinical assessment and magnetic resonance imaging (MRI) of the brain were carried out within 2 days for controls and within 2 weeks of hospitalization for patients. The Positive and Negative Syndrome Scale and Montreal Cognitive Assessment were applied to schizophrenia patients to assess symptoms and cognitive function, respectively.

RESULTS

Schizophrenia patients had significant volume deficit in bilateral amygdalae, bilateral superior temporal gyri, anterior cingulate cortex and bilateral hippocampi, along with a highly significant reduction in the length of right PCS. Schizophrenia patients with the duration of untreated psychosis (DUP) of 6-12 months showed a significantly greater volume of the right superior temporal gyrus (STG). First-episode schizophrenia patients had a significant reduction in the length of the left PCS. The volume of bilateral superior temporal gyri in schizophrenia patients showed a significant direct correlation with positive symptoms and an inverse correlation with negative symptoms.

CONCLUSION

Schizophrenia patients have significant volume deficit in some brain regions. DUP of 6-12 months is associated with significantly greater volume of the right STG. First-episode schizophrenia patients have a significant reduction in the length of the left PCS. In schizophrenia patients, the volume of bilateral superior temporal gyri showed a significant direct correlation with the positive symptoms and an inverse correlation with the negative symptoms.

Perceptual reality monitoring: Neural mechanisms dissociating imagination from reality

There is increasing evidence that imagination relies on similar neural mechanisms as externally triggered perception. This overlap presents a challenge for perceptual reality monitoring: deciding what is real and what is imagined. Here, we explore how perceptual reality monitoring might be implemented in the brain. We first describe sensory and cognitive factors that could dissociate imagery and perception and conclude that no single factor unambiguously signals whether an experience is internally or externally generated. We suggest that reality monitoring is implemented by higher-level cortical circuits that evaluate first-order sensory and cognitive factors to determine the source of sensory signals. According to this interpretation, perceptual reality monitoring shares core computations with metacognition. This multi-level architecture might explain several types of source confusion as well as dissociations between simply knowing whether something is real and actually experiencing it as real. We discuss avenues for future research to further our understanding of perceptual reality monitoring, an endeavour that has important implications for our understanding of clinical symptoms as well as general cognitive function.

Schizophrenia

Schizophrenia, characterised by psychotic symptoms and in many cases social and occupational decline, remains an aetiological and therapeutic challenge. Contrary to popular belief, the disorder is modestly more common in men than in women. Nor is the outcome uniformly poor. A division of symptoms into positive, negative, and disorganisation syndromes is supported by factor analysis. Catatonic symptoms are not specific to schizophrenia and so-called first rank symptoms are no longer considered diagnostically important. Cognitive impairment is now recognised as a further clinical feature of the disorder. Lateral ventricular enlargement and brain volume reductions of around 2% are established findings. Brain functional changes occur in different subregions of the frontal cortex and might ultimately be understandable in terms of disturbed interaction among large-scale brain networks. Neurochemical disturbance, involving dopamine function and glutamatergic N-methyl-D-aspartate receptor function, is supported by indirect and direct evidence. The genetic contribution to schizophrenia is now recognised to be largely polygenic. Birth and early life factors also have an important aetiological role. The mainstay of treatment remains dopamine receptor-blocking drugs; a psychological intervention, cognitive behavioural therapy, has relatively small effects on symptoms. The idea that schizophrenia is better regarded as the extreme end of a continuum of psychotic symptoms is currently influential. Other areas of debate include cannabis and childhood adversity as causative factors, whether there is progressive brain change after onset, and the long-term success of early intervention initiatives.

Prenatal Gyrification Pattern Affects Age at Onset in Frontotemporal Dementia

The paracingulate sulcus is a tertiary sulcus formed during the third trimester. In healthy individuals paracingulate sulcation is more prevalent in the left hemisphere. The anterior cingulate and paracingulate gyri are focal points of neurodegeneration in behavioral variant frontotemporal dementia (bvFTD). This study aims to determine the prevalence and impact of paracingulate sulcation in bvFTD. Structural magnetic resonance images of individuals with bvFTD (n = 105, mean age 66.9 years), Alzheimer's disease (n = 92, 73.3), and healthy controls (n = 110, 62.4) were evaluated using standard protocol for hemispheric paracingulate sulcal presence. No difference in left hemisphere paracingulate sulcal frequency was observed between groups; 0.72, 0.79, and 0.70, respectively, in the bvFTD, Alzheimer's disease, and healthy control groups, (P = 0.3). A significant impact of right (but not left) hemispheric paracingulate sulcation on age at disease onset was identified in bvFTD (mean 60.4 years where absent vs. 63.8 where present [P = 0.04, Cohen's d = 0.42]). This relationship was not observed in Alzheimer's disease. These findings demonstrate a relationship between prenatal neuronal development and the expression of a neurodegenerative disease providing a gross morphological example of brain reserve.

Training-Dependent Change in Content of Association in Appetitive Pavlovian Conditioning

In appetitive Pavlovian conditioning, experience with a conditional relationship between a cue [conditioned stimulus (CS)] and a reward [unconditioned stimulus (US)] bestows CS with the ability to promote adaptive behavior patterns. Different features of US (e.g., identity-specific sensory, general motivational) can be encoded by CS based on the nature of the CS-US relationship experienced (e.g., temporal factors such as training amount) and the content of association may determine the influence of CS over behavior (e.g., mediated learning, conditioned reinforcement). The content of association changed with varying conditioning factors, thereby altering behavioral consequences, however, has never been addressed in relevant brain signals evoked by CS. Our previous study found that phospholipase C β1-knockout (PLCβ1-KO) mice display persistent mediated learning over the extended course of odor-sugar conditioning, and that wild-type (WT) mice lose mediated learning sensitivity after extended training. In this study, in order to see whether this behavioral difference between these two genotypes comes from a difference in the course of association content, we examined whether odor CS can evoke the taste sensory representation of an absent sugar US after minimal- and extended training in these mice. In contrast to WT, which lost CS-evoked neural activation (c-Fos expression) in the gustatory cortex after extended training, KO mice displayed persistent association with the sensory feature of sugar, suggesting that sensory encoding is reliably linked to mediated learning sensitivity and there is a training-dependent change in the content of association in WT. PLCβ1 knockdown in the left medial prefrontal cortex (mPFC) resulted in mediated learning sensitivity and CS-evoked gustatory cortical activation after extended training, proposing a molecular component of the neural system underlying this Pavlovian conditioning process. We also discuss how disruption of this process is implicated for hallucination-like behaviors (impaired reality testing).

Modulating medial prefrontal cortex activity using real-time fMRI neurofeedback: Effects on reality monitoring performance and associated functional connectivity

Neuroimaging studies have found ‘reality monitoring’, our ability to distinguish internally generated experiences from those derived from the external world, to be associated with activity in the medial prefrontal cortex (mPFC) of the brain. Here we probe the functional underpinning of this ability using real-time fMRI neurofeedback to investigate the involvement of mPFC in recollection of the source of self-generated information. Thirty-nine healthy individuals underwent neurofeedback training in a between groups study receiving either Active feedback derived from the paracingulate region of the mPFC (21 subjects) or Sham feedback based on a similar level of randomised signal (18 subjects). Compared to those in the Sham group, participants receiving Active signal showed increased mPFC activity over the course of three real-time neurofeedback training runs undertaken in a single scanning session. Analysis of resting state functional connectivity associated with changes in reality monitoring accuracy following Active neurofeedback revealed increased connectivity between dorsolateral frontal regions of the fronto-parietal network (FPN) and the mPFC region of the default mode network (DMN), together with reduced connectivity within ventral regions of the FPN itself. However, only a trend effect was observed in the interaction of the recollection of the source of Imagined information compared with recognition memory between participants receiving Active and Sham neurofeedback, pre- and post- scanning. As such, these findings demonstrate that neurofeedback can be used to modulate mPFC activity and increase cooperation between the FPN and DMN, but the effects on reality monitoring performance are less clear.

Brain Mechanisms Underlying the Subjective Experience of Remembering

The ability to remember events in vivid, multisensory detail is a significant part of human experience, allowing us to relive previous encounters and providing us with the store of memories that shape our identity. Recent research has sought to understand the subjective experience of remembering, that is, what it feels like to have a memory. Such remembering involves reactivating sensory-perceptual features of an event and the thoughts and feelings we had when the event occurred, integrating them into a conscious first-person experience. It allows us to reflect on the content of our memories and to understand and make judgments about them, such as distinguishing events that actually occurred from those we might have imagined or been told about. In this review, we consider recent evidence from functional neuroimaging in healthy participants and studies of neurological and psychiatric conditions, which is shedding new light on how we subjectively experience remembering. Expected final online publication date for the Annual Review of Psychology, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Towards Deciphering the Fetal Foundation of Normal Cognition and Cognitive Symptoms From Sulcation of the Cortex

Growing evidence supports that prenatal processes play an important role for cognitive ability in normal and clinical conditions. In this context, several neuroimaging studies searched for features in postnatal life that could serve as a proxy for earlier developmental events. A very interesting candidate is the sulcal, or sulco-gyral, patterns, macroscopic features of the cortex anatomy related to the fold topology-e.g., continuous vs. interrupted/broken fold, present vs. absent fold-or their spatial organization. Indeed, as opposed to quantitative features of the cortical sheet (e.g., thickness, surface area or curvature) taking decades to reach the levels measured in adult, the qualitative sulcal patterns are mainly determined before birth and stable across the lifespan. The sulcal patterns therefore offer a window on the fetal constraints on specific brain areas on cognitive abilities and clinical symptoms that manifest later in life. After a global review of the cerebral cortex sulcation, its mechanisms, its ontogenesis along with methodological issues on how to measure the sulcal patterns, we present a selection of studies illustrating that analysis of the sulcal patterns can provide information on prenatal dispositions to cognition (with a focus on cognitive control and academic abilities) and cognitive symptoms (with a focus on schizophrenia and bipolar disorders). Finally, perspectives of sulcal studies are discussed.

Neuroanatomical correlates of reality monitoring in patients with schizophrenia and auditory hallucinations

Background

Reality-monitoring process enables to discriminate memories of internally generated information from memories of externally derived information. Studies have reported impaired reality-monitoring abilities in schizophrenia patients with auditory hallucinations (AHs), specifically with an exacerbated externalization bias, as well as alterations in neural activity within frontotemporoparietal areas. In healthy subjects, impaired reality-monitoring abilities have been associated with reduction of the paracingulate sulcus (PCS). The current study aimed to identify neuroanatomical correlates of reality monitoring in patients with schizophrenia.

Methods

Thirty-five patients with schizophrenia and AHs underwent a reality-monitoring task and a 3D anatomical MRI scan at 1.5 T. PCS lengths were measured separately for each hemisphere, and whole-brain voxel-based morphometry analyses were performed using the Computational Anatomy Toolbox (version 12.6) to evaluate the gray-matter volume (GMV). Partial correlation analyses were used to investigate the relationship between reality-monitoring and neuroanatomical outcomes (PCS length and GMV), with age and intracranial volume as covariates.

Results

The right PCS length was positively correlated with reality-monitoring accuracy (Spearman’s ρ = 0.431, p = 0.012) and negatively with the externalization bias (Spearman’s ρ = −0.379, p = 0.029). Reality-monitoring accuracy was positively correlated with GMV in the right angular gyrus, whereas externalization bias was negatively correlated with GMV in the left supramarginal gyrus/superior temporal gyrus, in the right lingual gyrus and in the bilateral inferior temporal/fusiform gyri (voxel-level p < 0.001 and cluster-level p < 0.05, FDR-corrected).

Conclusions

Reduced reality-monitoring abilities were significantly associated with shorter right PCS and reduced GMV in temporal and parietal regions of the reality-monitoring network in schizophrenia patients with AHs.

Neural Correlates of Aberrant Salience and Source Monitoring in Schizophrenia and At-Risk Mental States-A Systematic Review of fMRI Studies

Cognitive biases are an important factor contributing to the development and symptom severity of psychosis. Despite the fact that various cognitive biases are contributing to psychosis, they are rarely investigated together. In the current systematic review, we aimed at investigating specific and shared functional neural correlates of two important cognitive biases: aberrant salience and source monitoring. We conducted a systematic search of fMRI studies of said cognitive biases. Eight studies on aberrant salience and eleven studies on source monitoring were included in the review. We critically discussed behavioural and neuroimaging findings concerning cognitive biases. Various brain regions are associated with aberrant salience and source monitoring in individuals with schizophrenia and the risk of psychosis. The ventral striatum and insula contribute to aberrant salience. The medial prefrontal cortex, superior and middle temporal gyrus contribute to source monitoring. The anterior cingulate cortex and hippocampus contribute to both cognitive biases, constituting a neural overlap. Our review indicates that aberrant salience and source monitoring may share neural mechanisms, suggesting their joint role in producing disrupted external attributions of perceptual and cognitive experiences, thus elucidating their role in positive symptoms of psychosis. Account bridging mechanisms of these two biases is discussed. Further studies are warranted.

Cognitive insights from tertiary sulci in prefrontal cortex

The lateral prefrontal cortex (LPFC) is disproportionately expanded in humans compared to non-human primates, although the relationship between LPFC brain structures and uniquely human cognitive skills is largely unknown. Here, we test the relationship between variability in LPFC tertiary sulcal morphology and reasoning scores in a cohort of children and adolescents. Using a data-driven approach in independent discovery and replication samples, we show that the depth of specific LPFC tertiary sulci is associated with individual differences in reasoning scores beyond age. To expedite discoveries in future neuroanatomical-behavioral studies, we share tertiary sulcal definitions with the field. These findings support a classic but largely untested theory linking the protracted development of tertiary sulci to late-developing cognitive processes.

Using Tertiary Sulci to Map the "Cognitive Globe" of Prefrontal Cortex

Stuss considered the human PFC as a "cognitive globe" [Stuss, D. T., & Benson, D. F. Neuropsychological studies of the frontal lobes. Psychological Bulletin, 95, 3-28, 1984] on which functions of the frontal lobe could be mapped. Here, we discuss classic and recent findings regarding the evolution, development, function, and cognitive role of shallow indentations or tertiary sulci in PFC, with the goal of using tertiary sulci to map the "cognitive globe" of PFC. First, we discuss lateral PFC (LPFC) tertiary sulci in classical anatomy and modern neuroimaging, as well as their development, with a focus on those within the middle frontal gyrus. Second, we discuss tertiary sulci in comparative neuroanatomy, focusing on primates. Third, we summarize recent findings showing the utility of tertiary sulci for understanding structural-functional relationships with functional network insights in ventromedial PFC and LPFC. Fourth, we revisit and update unresolved theoretical perspectives considered by C. Vogt and O. Vogt (Allgemeinere ergebnisse unserer hirnforschung. Journal für Psychologie und Neurologie, 25, 279-462, 1919) and F. Sanides (Structure and function of the human frontal lobe. Neuropsychologia, 2, 209-219, 1964) that tertiary sulci serve as landmarks for cortical gradients. Together, the consideration of these classic and recent findings indicate that tertiary sulci are situated in a unique position within the complexity of the "cognitive globe" of PFC: They are the smallest and shallowest of sulci in PFC, yet can offer insights that bridge spatial scales (microns to networks), modalities (functional connectivity to behavior), and species. As such, the map of tertiary sulci within each individual participant serves as a coordinate system specific to that individual on which functions may be further mapped. We conclude with new theoretical and methodological questions that, if answered in future research, will likely lead to mechanistic insight regarding the structure and function of human LPFC.

The Paracingulate Sulcus Is a Unique Feature of the Medial Frontal Cortex Shared by Great Apes and Humans

Primate brains display a wide range of variation in size and cerebral gyrification, leading to the appearance of novel sulci in particular groups of species. We investigated sulcal organization in the medial frontal cortex of great apes, with a particular focus on the paracingulate sulcus (PCGS). Until recently, the presence of the PCGS was thought to be a structural feature unique to the human brain. However, upon closer examination, the PCGS has been observed as a variable feature that also may appear in chimpanzee brains. To understand the evolutionary origins of the sulcal anatomy in the medial frontal cortex of apes, we examined high-resolution MRI scans for the presence or absence of the PCGS and, when present, measured its length in a sample of ape brains (chimpanzees, bonobos, gorillas, orangutans, gibbons, and siamangs). We found that the PCGS is variable in its appearance among these species, being present in 23 to 50% of great ape individuals depending on the species, but not present in gibbons or siamangs. We did not find population level hemispheric lateralization patterns or sex differences in PCGS presence across species, and we did not detect a relationship between cerebral volume and PCGS occurrence or length. Our data suggest that the PCGS is a common sulcal variant present in great apes and humans due to a shared evolutionary ancestry.

Revisiting the Morphology and Classification of the Paracingulate Gyrus with Commentaries on Ambiguous Cases

The anterior cingulate cortex is considered to play a crucial role in cognitive and affective regulation. However, this area shows a high degree of morphological interindividual variability and asymmetry. It is especially true regarding the paracingulate sulcus and paracingulate gyrus (PCG). Since the reports described in the literature are mainly based on imaging techniques, the goal of this study was to verify the classification of the PCG based on anatomical material. Special attention was given to ambiguous cases. The PCG was absent in 26.4% of specimens. The gyrus was classified as present in 28.3% of cases. The prominent type of the PCG was observed in 37.7% of the total. Occasionally, the gyrus was well-developed and roughly only a few millimeters were missing for classifying the gyrus as prominent, as it ended slightly anterior the level of the VAC. The remaining four cases involved two inconclusive types. We observed that the callosomarginal artery ran within the cingulate sulcus and provided branches that crossed the PCG. Based on Klingler’s dissection technique, we observed a close relationship of the PCG with the superior longitudinal fascicle. The awareness of the anatomical variability observed within the brain cortex is an essential starting point for in-depth research.

Lesions causing hallucinations localize to one common brain network

The brain regions responsible for hallucinations remain unclear. We studied 89 brain lesions causing hallucinations using a recently validated technique termed lesion network mapping. We found that hallucinations occurred following lesions to a variety of different brain regions, but these lesion locations fell within a single functionally connected brain network. This network was defined by connectivity to the cerebellar vermis, inferior cerebellum (bilateral lobule X), and the right superior temporal sulcus. Within this single hallucination network, additional connections with the lesion location dictated the sensory modality of the hallucination: lesions causing visual hallucinations were connected to the lateral geniculate nucleus in the thalamus while lesions causing auditory hallucinations were connected to the dentate nucleus in the cerebellum. Our results suggest that lesions causing hallucinations localize to a single common brain network, but additional connections within this network dictate the sensory modality, lending insight into the causal neuroanatomical substrate of hallucinations.

Labeling lateral prefrontal sulci using spherical data augmentation and context-aware training

The inference of cortical sulcal labels often focuses on deep (primary and secondary) sulcal regions, whereas shallow (tertiary) sulcal regions are largely overlooked in the literature due to the scarcity of manual/well-defined annotations and their large neuroanatomical variability. In this paper, we present an automated framework for regional labeling of both primary/secondary and tertiary sulci of the dorsal portion of lateral prefrontal cortex (LPFC) using spherical convolutional neural networks. We propose two core components that enhance the inference of sulcal labels to overcome such large neuroanatomical variability: (1) surface data augmentation and (2) context-aware training. (1) To take into account neuroanatomical variability, we synthesize training data from the proposed feature space that embeds intermediate deformation trajectories of spherical data in a rigid to non-rigid fashion, which bridges an augmentation gap in conventional rotation data augmentation. (2) Moreover, we design a two-stage training process to improve labeling accuracy of tertiary sulci by informing the biological associations in neuroanatomy: inference of primary/secondary sulci and then their spatial likelihood to guide the definition of tertiary sulci. In the experiments, we evaluate our method on 13 deep and shallow sulci of human LPFC in two independent data sets with different age ranges: pediatric (N=60) and adult (N=36) cohorts. We compare the proposed method with a conventional multi-atlas approach and spherical convolutional neural networks without/with rotation data augmentation. In both cohorts, the proposed data augmentation improves labeling accuracy of deep and shallow sulci over the baselines, and the proposed context-aware training offers further improvement in the labeling of shallow sulci over the proposed data augmentation. We share our tools with the field and discuss applications of our results for understanding neuroanatomical-functional organization of LPFC and the rest of cortex (https://github.com/ilwoolyu/SphericalLabeling).

Overlooked Tertiary Sulci Serve as a Meso-Scale Link between Microstructural and Functional Properties of Human Lateral Prefrontal Cortex

Understanding the relationship between neuroanatomy and function in portions of cortex that perform functions largely specific to humans such as lateral prefrontal cortex (LPFC) is of major interest in systems and cognitive neuroscience. When considering neuroanatomical-functional relationships in LPFC, shallow indentations in cortex known as tertiary sulci have been largely unexplored. Here, by implementing a multimodal approach and manually defining 936 neuroanatomical structures in 72 hemispheres (in both males and females), we show that a subset of these overlooked tertiary sulci serve as a meso-scale link between microstructural (myelin content) and functional (network connectivity) properties of human LPFC in individual participants. For example, the posterior middle frontal sulcus (pmfs) is a tertiary sulcus with three components that differ in their myelin content, resting-state connectivity profiles, and engagement across meta-analyses of 83 cognitive tasks. Further, generating microstructural profiles of myelin content across cortical depths for each pmfs component and the surrounding middle frontal gyrus (MFG) shows that both gyral and sulcal components of the MFG have greater myelin content in deeper compared with superficial layers and that the myelin content in superficial layers of the gyral components is greater than sulcal components. These findings support a classic, yet largely unconsidered theory that tertiary sulci may serve as landmarks in association cortices, as well as a modern cognitive neuroscience theory proposing a functional hierarchy in LPFC. As there is a growing need for computational tools that automatically define tertiary sulci throughout cortex, we share pmfs probabilistic sulcal maps with the field.SIGNIFICANCE STATEMENT Lateral prefrontal cortex (LPFC) is critical for functions that are thought to be specific to humans compared with other mammals. However, relationships between fine-scale neuroanatomical structures largely specific to hominoid cortex and functional properties of LPFC remain elusive. Here, we show that these structures, which have been largely unexplored throughout history, surprisingly serve as markers for anatomical and functional organization in human LPFC. These findings have theoretical, methodological, developmental, and evolutionary implications for improved understanding of neuroanatomical-functional relationships not only in LPFC, but also in association cortices more broadly. Finally, these findings ignite new questions regarding how morphological features of these neglected neuroanatomical structures contribute to functions of association cortices that are critical for human-specific aspects of cognition.

Evidence in cortical folding patterns for prenatal predispositions to hallucinations in schizophrenia

All perception is a construction of the brain from sensory input. Our first perceptions begin during gestation, making fetal brain development fundamental to how we experience a diverse world. Hallucinations are percepts without origin in physical reality that occur in health and disease. Despite longstanding research on the brain structures supporting hallucinations and on perinatal contributions to the pathophysiology of schizophrenia, what links these two distinct lines of research remains unclear. Sulcal patterns derived from structural magnetic resonance (MR) images can provide a proxy in adulthood for early brain development. We studied two independent datasets of patients with schizophrenia who underwent clinical assessment and 3T MR imaging from the United Kingdom and Shanghai, China (n = 181 combined) and 63 healthy controls from Shanghai. Participants were stratified into those with (n = 79 UK; n = 22 Shanghai) and without (n = 43 UK; n = 37 Shanghai) hallucinations from the PANSS P3 scores for hallucinatory behaviour. We quantified the length, depth, and asymmetry indices of the paracingulate and superior temporal sulci (PCS, STS), which have previously been associated with hallucinations in schizophrenia, and constructed cortical folding covariance matrices organized by large-scale functional networks. In both ethnic groups, we demonstrated a significantly shorter left PCS in patients with hallucinations compared to those without, and to healthy controls. Reduced PCS length and STS depth corresponded to focal deviations in their geometry and to significantly increased covariance within and between areas of the salience and auditory networks. The discovery of neurodevelopmental alterations contributing to hallucinations establishes testable models for these enigmatic, sometimes highly distressing, perceptions and provides mechanistic insight into the pathological consequences of prenatal origins.

A Review of Multimodal Hallucinations: Categorization, Assessment, Theoretical Perspectives, and Clinical Recommendations

Hallucinations can occur in different sensory modalities, both simultaneously and serially in time. They have typically been studied in clinical populations as phenomena occurring in a single sensory modality. Hallucinatory experiences occurring in multiple sensory systems-multimodal hallucinations (MMHs)-are more prevalent than previously thought and may have greater adverse impact than unimodal ones, but they remain relatively underresearched. Here, we review and discuss: (1) the definition and categorization of both serial and simultaneous MMHs, (2) available assessment tools and how they can be improved, and (3) the explanatory power that current hallucination theories have for MMHs. Overall, we suggest that current models need to be updated or developed to account for MMHs and to inform research into the underlying processes of such hallucinatory phenomena. We make recommendations for future research and for clinical practice, including the need for service user involvement and for better assessment tools that can reliably measure MMHs and distinguish them from other related phenomena.