RESUMEN

The executive control process of monitoring information in working memory depends on the mid-dorsolateral prefrontal cortical region (cytoarchitectonic areas 46 and 9/46) in interaction with the hippocampal memory system. Anatomical studies demonstrated strong connectivity between the mid-dorsolateral prefrontal cortex and the medial parietal area PGm that lies on the precuneus. Area PGm is also strongly connected with the attentional system on the lateral inferior parietal lobule (area PG) and the limbic retrosplenial/posterior cingulate region that interacts with the hippocampal memory system. Thus, in terms of anatomical connectivity, area PGm appears to be a critical node for the integration of executive control processing from the prefrontal cortex with the online attentional and memory related processing. This hypothesis was tested in macaque monkeys with the crossed unilateral lesion methodology. A unilateral lesion in the mid-dorsolateral prefrontal cortex was combined with a unilateral lesion in area PGm in the opposite hemisphere. The results demonstrated an impairment on the externally ordered working memory task that assesses the monitoring of information in working memory. Thus, the medial parietal area PGm is a critical node in mediating the functional interaction between the prefrontal region for the executive control process of monitoring information and the memory system.

Asunto(s)

Memoria a Corto Plazo , Lóbulo Parietal , Animales , Memoria a Corto Plazo/fisiología , Lóbulo Parietal/fisiología , Masculino , Vías Nerviosas/fisiología , Macaca mulatta , Corteza Prefontal Dorsolateral/fisiología , Corteza Prefrontal/fisiología

RESUMEN

The intersection of neuroscience and technology hinges on the development of wearable devices and electrodes that can augment brain networks to improve cognitive capabilities such as learning and concentration. The capacity to enhance networks associated with these functions above baseline capabilities, holds the potential to benefit numerous individuals. The purpose of this study was to determine if electromagnetic field exposure modeled from physiological data would increase instances of flow in participants playing a computer game. The flow state refers to a subjective state of optimal performance experienced by individuals during a variety of tasks. For this study, participants (n = 39, 18-65 years, nfemale = 20) played the arcade game Snake for two ten-minute periods (each with a ten-minute rest period immediately following). For one of the trials, an electromagnetic field was applied bilaterally to the temporal lobes, with the other serving as the control. Brain activity was measured using quantitative electroencephalography, flow experience was measured using the Flow Short Scale and game play scores were also recorded. Results showed deceased beta 1 (12-16 Hz) activity in the left cuneus [t = 4.650, p < 0.01] and left precuneus [t = 4.603, p < 0.01], left posterior cingulate [t = 4.521, p < 0.05], insula [t = 4.234, p < 0.05], and parahippocampal gyrus [t = 4.113, p < 0.05] for trials when the field was active, compared to controls during rest periods. Results from the Flow Short Scale showed a statistically significant difference in mean "concentration ease" scores across electromagnetic field conditions, irrespective of difficulty [t = 2.131, p < 0.05]. In the EMF exposure trials, there was no discernible experience effect; participants with prior experience in the game Snake did not exhibit significantly better performance compared to those without prior experience. This anticipated effect was observed in control conditions. The comparable performance observed between novices and experienced players in the EMF condition indicate a noteworthy learning curve for novices. In all, these results provide evidence supporting the ability of EMF patterned from amygdaloid firing (6-20 Hz) to elicit neurological correlates of flow in brain regions previously reported in the literature, facilitate concentration, and subtly improve game scores. The possibility for wearable devices to support learning, concentration, and focus are discussed.

Asunto(s)

Electroencefalografía , Campos Electromagnéticos , Juegos de Video , Humanos , Adulto , Masculino , Adulto Joven , Femenino , Electroencefalografía/métodos , Encéfalo/fisiología , Persona de Mediana Edad , Adolescente , Autoinforme

RESUMEN

Background: A range of imaging modalities have reported Alzheimer's disease-related abnormalities in individuals experiencing subjective cognitive decline (SCD). However, there has been no consistent local abnormality identified across multiple neuroimaging modalities for SCD. Objective: We aimed to investigate the convergent local alterations in amyloid-ß (Aß) deposition, glucose metabolism, and resting-state functional MRI (RS-fMRI) metrics in SCD. Methods: Fifty SCD patients (66.4±5.7 years old, 19 men [38%]) and 15 normal controls (NC) (66.3±4.4 years old, 5 men [33.3%]) were scanned with both [18F]-florbetapir PET and [18F]-fluorodeoxyglucose PET, as well as simultaneous RS-fMRI from February 2018 to November 2018. Voxel-wise metrics were retrospectively analyzed, including Aß deposition, glucose metabolism, amplitude of low frequency fluctuation (ALFF), regional homogeneity (ReHo), and degree centrality(DC). Results: The SCD group showed increased Aß deposition and glucose metabolism (p < 0.05, corrected), as well as decreased ALFF, ReHo, and DC (p < 0.05, uncorrected) in the left dorsal precuneus (dPCu). Furthermore, the dPCu illustrated negative resting-state functional connectivity with the default mode network. Regarding global Aß deposition positivity, the Aß deposition in the left dPCu showed a gradient change, i.e., Aß positive SCD > Aß negative SCD > Aß negative NC. Additionally, both Aß positive SCD and Aß negative SCD showed increased glucose metabolism and decreased RS-fMRI metrics in the dPCu. Conclusions: The dorsal precuneus, an area implicated in early AD, shows convergent neuroimaging alterations in SCD, and might be more related to other cognitive functions (e.g., unfocused attention) than episodic memory.

Asunto(s)

Disfunción Cognitiva , Imagen por Resonancia Magnética , Imagen Multimodal , Lóbulo Parietal , Tomografía de Emisión de Positrones , Humanos , Masculino , Disfunción Cognitiva/diagnóstico por imagen , Femenino , Anciano , Lóbulo Parietal/diagnóstico por imagen , Lóbulo Parietal/metabolismo , Persona de Mediana Edad , Péptidos beta-Amiloides/metabolismo , Fluorodesoxiglucosa F18 , Estudios Retrospectivos , Glucosa/metabolismo

RESUMEN

Alzheimer's Disease (AD) is characterized by structural and functional dysfunction involving the Default Mode Network (DMN), for which the Precuneus (PC) is a key node. We proposed a randomized double-blind pilot study to determine neurobiological changes after 24 weeks of PC-rTMS in patients with mild-to-moderate AD. Sixteen patients were randomly assigned to SHAM or PC-rTMS, and received an intensive 2-weeks course with daily rTMS sessions, followed by a maintenance phase in which rTMS has been applied once a week. Before and after the treatment structural and functional MRIs were collected. Our results showed macro- and micro-structural preservation in PC-rTMS compared to SHAM-rTMS group after 24 weeks of treatment, correlated to an increase of functional connectivity (FC) within the PC in the PC-rTMS group. Even if preliminary, these results trigger the possibility of using PC-rTMS to arrest atrophy progression by manipulating distributed network connectivity patterns.

Asunto(s)

Enfermedad de Alzheimer , Sustancia Gris , Imagen por Resonancia Magnética , Estimulación Magnética Transcraneal , Humanos , Enfermedad de Alzheimer/terapia , Enfermedad de Alzheimer/diagnóstico por imagen , Enfermedad de Alzheimer/patología , Proyectos Piloto , Masculino , Femenino , Anciano , Método Doble Ciego , Estimulación Magnética Transcraneal/métodos , Sustancia Gris/diagnóstico por imagen , Sustancia Gris/patología , Persona de Mediana Edad , Resultado del Tratamiento , Lóbulo Parietal/diagnóstico por imagen , Lóbulo Parietal/patología

RESUMEN

Discrepancies in self-rated and observer-rated depression severity may underlie the basis for biological heterogeneity in depressive disorders and be an important predictor of outcomes and indicators to optimize intervention strategies. However, the neural mechanisms underlying this discrepancy have been understudied. This study aimed to examine the brain networks that represent the neural basis of the discrepancy between self-rated and observer-rated depression severity using resting-state functional MRI. To examine the discrepancy between self-rated and observer-rated depression severity, self- and observer-ratings discrepancy (SOD) was defined, and the higher and lower SOD groups were selected from depressed patients as participants showing extreme deviation. Resting-state functional MRI analysis was performed to examine regions with significant differences in functional connectivity in the two groups. The results showed that, in the higher SOD group compared to the lower SOD group, there was increased functional connectivity between the frontal pole and precuneus, both of which are subregions of the default mode network that have been reported to be associated with ruminative and self-referential thinking. These results provide insight into the association of brain circuitry with discrepancies between self- and observer-rated depression severity and may lead to more treatment-oriented diagnostic reclassification in the future.

Asunto(s)

Depresión , Lóbulo Frontal , Imagen por Resonancia Magnética , Lóbulo Parietal , Humanos , Imagen por Resonancia Magnética/métodos , Femenino , Masculino , Adulto , Lóbulo Parietal/diagnóstico por imagen , Lóbulo Parietal/fisiopatología , Lóbulo Frontal/diagnóstico por imagen , Lóbulo Frontal/fisiopatología , Depresión/diagnóstico por imagen , Depresión/fisiopatología , Depresión/psicología , Persona de Mediana Edad , Adulto Joven , Trastornos del Humor/diagnóstico por imagen , Trastornos del Humor/fisiopatología , Trastornos del Humor/psicología , Autoinforme , Vías Nerviosas/fisiopatología , Vías Nerviosas/diagnóstico por imagen , Descanso , Red Nerviosa/diagnóstico por imagen , Red Nerviosa/fisiopatología , Índice de Severidad de la Enfermedad , Mapeo Encefálico/métodos

RESUMEN

Neuroimaging studies have consistently demonstrated concurrent activation of the human precuneus and temporal pole (TP), both during resting-state conditions and various higher-order cognitive functions. However, the precise underlying structural connectivity between these brain regions remains uncertain despite significant advancements in neuroscience research. In this study, we investigated the connectivity of the precuneus and TP by employing parcellation-based fiber micro-dissections in human brains and fiber tractography techniques in a sample of 1065 human subjects and a sample of 41 rhesus macaques. Our results demonstrate the connectivity between the posterior precuneus area POS2 and the areas 35, 36, and TG of the TP via the fifth subcomponent of the cingulum (CB-V) also known as parahippocampal cingulum. This finding contributes to our understanding of the connections within the posteromedial cortices, facilitating a more comprehensive integration of anatomy and function in both normal and pathological brain processes. PRACTITIONER POINTS: Our investigation delves into the intricate architecture and connectivity patterns of subregions within the precuneus and temporal pole, filling a crucial gap in our knowledge. We revealed a direct axonal connection between the posterior precuneus (POS2) and specific areas (35, 35, and TG) of the temporal pole. The direct connections are part of the CB-V pathway and exhibit a significant association with the cingulum, SRF, forceps major, and ILF. Population-based human tractography and rhesus macaque fiber tractography showed consistent results that support micro-dissection outcomes.

Asunto(s)

Imagen de Difusión Tensora , Macaca mulatta , Vías Nerviosas , Lóbulo Parietal , Lóbulo Temporal , Humanos , Lóbulo Temporal/diagnóstico por imagen , Lóbulo Temporal/fisiología , Lóbulo Temporal/anatomía & histología , Lóbulo Parietal/diagnóstico por imagen , Lóbulo Parietal/fisiología , Lóbulo Parietal/anatomía & histología , Animales , Imagen de Difusión Tensora/métodos , Masculino , Adulto , Femenino , Vías Nerviosas/diagnóstico por imagen , Vías Nerviosas/anatomía & histología , Vías Nerviosas/fisiología , Adulto Joven , Axones/fisiología , Conectoma , Sustancia Blanca/diagnóstico por imagen , Sustancia Blanca/anatomía & histología , Sustancia Blanca/fisiología , Giro del Cíngulo/diagnóstico por imagen , Giro del Cíngulo/fisiología , Giro del Cíngulo/anatomía & histología

RESUMEN

How to fairly allocate goods is a key issue of social decision-making. Extensive research demonstrates that people do not selfishly maximize their own benefits, but instead also consider how others are affected. However, most accounts of the psychological processes underlying fairness-related behavior implicitly assume that assessments of fairness are somewhat stable. In this paper, we present results of a novel task, the Re-Allocation Game, in which two players receive an allocation determined by the computer and, on half of the trials, one player has the subsequent possibility to change this allocation. Importantly, prior to the receipt of the allocation, players were shown either their respective financial situations, their respective performance on a previous simple task, or random information, while being scanned using functional neuroimaging. As expected, our results demonstrate when given the opportunity, participants allocated on average almost half the money to anonymous others. However, our findings further show that participants used the provided information in a dynamic manner, revealing the underlying principle based on which people re-allocate money - namely based on merit, need, or equality - switches dynamically. On the neural level, we identified activity in the right and left dorsolateral prefrontal cortices related to context-independent inequity and context-dependent fairness information respectively when viewing the computer-generated allocations. At the same time, activity in the temporoparietal and precuneus represented these different types of fairness-related information in adjacent and partially overlapping clusters. Finally, we observed that the activity pattern in the precuneus and putamen was most clearly related to participants' subsequent re-allocation decisions. Together, our findings suggest that participants judge an allocation as fair or unfair using a network associated with cognitive control and theory-of-mind, while dynamically switching between what might constitute a fair allocation in a particular context.

Asunto(s)

Toma de Decisiones , Imagen por Resonancia Magnética , Principios Morales , Humanos , Toma de Decisiones/fisiología , Masculino , Femenino , Adulto , Adulto Joven , Mapeo Encefálico , Encéfalo/fisiología , Encéfalo/diagnóstico por imagen

RESUMEN

BACKGROUND: Theoretical and empirical evidence indicates the critical role of the default mode network (DMN) in the pathophysiology of the bipolar disorder (BD). This study aims to identify the specific brain regions of the DMN that is impaired in patients with BD. METHODS: A total of 56 patients with BD and 71 healthy controls (HC) underwent resting-state functional magnetic resonance imaging. Three commonly used functional indices, i.e., fractional amplitude of low-frequency fluctuation (fALFF), regional homogeneity (ReHo), and degree centrality (DC), were utilized to identify the brain region showing abnormal spontaneous brain activity in patients with BD. Then, this region served as the seed region for resting-state functional connectivity (rsFC) analysis. RESULTS: Compared to the HC group, the BD group showed reduced fALFF, ReHo, and DC values in the left precuneus. Moreover, patients exhibited decreased rsFCs within the left precuneus and between the left precuneus and the medial prefrontal cortex. Additionally, there was diminished negative connectivity between the left precuneus and the left putamen, extending to the left insula (putamen/insula). The abnormalities in DMN functional connectivity were confirmed through various analysis strategies. CONCLUSIONS: Our findings provide convergent evidence for the abnormalities in the DMN, particularly located in the left precuneus. Decreased functional connectivity within the DMN and the reduced anticorrelation between the DMN and the salience network are found in patients with BD. These findings suggest that the DMN is a key aspect for understanding the neural basis of BD, and the altered functional patterns of DMN may be a potential candidate biomarker for diagnosis of BD.

Asunto(s)

Trastorno Bipolar , Red en Modo Predeterminado , Imagen por Resonancia Magnética , Humanos , Trastorno Bipolar/fisiopatología , Trastorno Bipolar/diagnóstico por imagen , Femenino , Masculino , Adulto , Red en Modo Predeterminado/fisiopatología , Red en Modo Predeterminado/diagnóstico por imagen , Red Nerviosa/fisiopatología , Red Nerviosa/diagnóstico por imagen , Lóbulo Parietal/fisiopatología , Lóbulo Parietal/diagnóstico por imagen , Conectoma/métodos , Corteza Prefrontal/fisiopatología , Corteza Prefrontal/diagnóstico por imagen , Estudios de Casos y Controles , Adulto Joven , Persona de Mediana Edad , Encéfalo/fisiopatología , Encéfalo/diagnóstico por imagen , Mapeo Encefálico

RESUMEN

Moral identity is an important moral variable which has positive moral functions, such as contributing to prosocial behaviours, reducing antisocial behaviours, and resisting the risk factors of antisocial behaviours. However, little is known about the neural correlates of moral identity and the neural basis of the effect of moral identity on the risk factors of antisocial behaviours, including moral disengagement. In this study, we explored these issues in 142 college students by estimating the regional homogeneity (ReHo) through resting-state functional magnetic resonance imaging (fMRI). The whole-brain correlation analyses found that higher internalized moral identity was correlated with higher ReHo in the precuneus. Furthermore, the ReHo in the precuneus was negatively correlated with moral disengagement, suggesting positive moral functions of the neural mechanisms of moral identity. These findings deepen our understanding of individual differences in moral identity and provide inspiration for the education of moral identity and the intervention for moral disengagement from the perspective of the brain.

RESUMEN

As adolescents acquire agency and become contributing members of society, it is necessary to understand how they help their community. Yet, it is unknown how prosocial behavior develops in the context of community-based prosocial behaviors that are relevant to adolescents, such as donating time to charities. In this longitudinal functional magnetic resonance imaging study, adolescents (N=172; mean age at wave 1=12.8) completed a prosocial task annually for three years (N=422 and 375 total behavioral and neural data points, respectively), and 14 days of daily diaries reporting on their prosocial behaviors two years later. During the task, adolescents decided how many minutes they would donate to a variety of local charities. We found that adolescents donated less time to charities from early to mid adolescence. Longitudinal whole-brain analyses revealed declines in ventrolateral prefrontal cortex (vlPFC) activation, as well as inverted U-shaped changes in precuneus activation when adolescents donated their time from early to mid adolescence. A less steep decrease in vlPFC activation predicted greater real-life prosocial behaviors in youth's daily lives two years later. Our study elucidates the neurodevelopmental mechanisms of prosocial behavior from early to mid adolescence that have enduring effects on daily prosocial behaviors in late adolescence.

Asunto(s)

Imagen por Resonancia Magnética , Corteza Prefrontal , Conducta Social , Humanos , Corteza Prefrontal/fisiología , Adolescente , Masculino , Femenino , Imagen por Resonancia Magnética/métodos , Estudios Longitudinales , Niño , Conducta del Adolescente/fisiología , Factores de Edad , Desarrollo del Adolescente/fisiología

RESUMEN

BACKGROUND: Mirror therapy (MT) has been shown to be effective for motor recovery of the upper limb after a stroke. The cerebral mechanisms of mirror therapy involve the precuneus, premotor cortex and primary motor cortex. Activation of the precuneus could be a marker of this effectiveness. MT has some limitations and video therapy (VT) tools are being developed to optimise MT. While the clinical superiority of these new tools remains to be demonstrated, comparing the cerebral mechanisms of these different modalities will provide a better understanding of the related neuroplasticity mechanisms. METHODS: Thirty-three right-handed healthy individuals were included in this study. Participants were equipped with a near-infrared spectroscopy headset covering the precuneus, the premotor cortex and the primary motor cortex of each hemisphere. Each participant performed 3 tasks: a MT task (right hand movement and left visual feedback), a VT task (left visual feedback only) and a control task (right hand movement only). Perception of illusion was rated for MT and VT by asking participants to rate the intensity using a visual analogue scale. The aim of this study was to compare brain activation during MT and VT. We also evaluated the correlation between the precuneus activation and the illusion quality of the visual mirrored feedback. RESULTS: We found a greater activation of the precuneus contralateral to the visual feedback during VT than during MT. We also showed that activation of primary motor cortex and premotor cortex contralateral to visual feedback was more extensive in VT than in MT. Illusion perception was not correlated with precuneus activation. CONCLUSION: VT led to greater activation of a parieto-frontal network than MT. This could result from a greater focus on visual feedback and a reduction in interhemispheric inhibition in VT because of the absence of an associated motor task. These results suggest that VT could promote neuroplasticity mechanisms in people with brain lesions more efficiently than MT. CLINICAL TRIAL REGISTRATION: NCT04738851.

Asunto(s)

Retroalimentación Sensorial , Corteza Motora , Espectroscopía Infrarroja Corta , Adulto , Femenino , Humanos , Masculino , Adulto Joven , Encéfalo/fisiología , Encéfalo/diagnóstico por imagen , Retroalimentación Sensorial/fisiología , Corteza Motora/fisiología , Corteza Motora/diagnóstico por imagen , Lóbulo Parietal/fisiología , Lóbulo Parietal/diagnóstico por imagen , Desempeño Psicomotor/fisiología , Espectroscopía Infrarroja Corta/métodos

RESUMEN

One potential application of forensic "brain reading" is to test whether a suspect has previously experienced a crime scene. Here, we investigated whether it is possible to decode real life autobiographic exposure to spatial locations using fMRI. In the first session, participants visited four out of eight possible rooms on a university campus. During a subsequent scanning session, subjects passively viewed pictures and videos from these eight possible rooms (four old, four novel) without giving any responses. A multivariate searchlight analysis was employed that trained a classifier to distinguish between "seen" versus "unseen" stimuli from a subset of six rooms. We found that bilateral precuneus encoded information that can be used to distinguish between previously seen and unseen rooms and that also generalized to the two stimuli left out from training. We conclude that activity in bilateral precuneus is associated with the memory of previously visited rooms, irrespective of the identity of the room, thus supporting a parietal contribution to episodic memory for spatial locations. Importantly, we could decode whether a room was visited in real life without the need of explicit judgments about the rooms. This suggests that recognition is an automatic response that can be decoded from fMRI data, thus potentially supporting forensic applications of concealed information tests for crime scene recognition.

Asunto(s)

Mapeo Encefálico , Imagen por Resonancia Magnética , Lóbulo Parietal , Reconocimiento en Psicología , Humanos , Masculino , Femenino , Lóbulo Parietal/fisiología , Lóbulo Parietal/diagnóstico por imagen , Adulto Joven , Reconocimiento en Psicología/fisiología , Mapeo Encefálico/métodos , Adulto , Estimulación Luminosa/métodos , Reconocimiento Visual de Modelos/fisiología , Percepción Espacial/fisiología , Memoria Episódica

RESUMEN

Background: Emotional abuse during childhood and adolescence is thought to be associated with the brain; however, the neural mechanism underlying the cognitive process remains unknown. Therefore, we aimed to investigate the mediating effect of negative automatic thoughts on the relationship between emotional abuse and resting-state functional connectivity (rsFC) during adolescence. Method: Our community sample included 54 adolescents aged 13-17 years in the statistical analysis. Resting-state functional and structural magnetic resonance imaging (MRI) was performed, while emotional abuse and negative automatic thoughts were assessed using self-reported scales. A mediation analysis was used to assess the contributions of early traumatic events and negative automatic thoughts to resting functional connectivity. Result: Higher negative automatic thoughts were associated with lower connectivity in the context of greater emotional abuse (i.e., suppression effect). Thus, the relationships between emotional abuse and connectivity in the precuneus (pCun)-medial prefrontal cortex, parahippocampal cortex-extrastriate cortex, and temporal cortex-temporal pole were decreased by negative automatic thoughts. In contrast, functional connections in the pCun-pCun, pCun-precuneus/posterior cingulate cortex, and nucleus accumbens-somatomotor areas were strongly mediated when emotionally abused adolescents reported a high tendency for negative automatic thoughts. Conclusion: Negative automatic thoughts strengthened the relationship between emotional abuse and rsFC. These findings highlight the underlying cognitive processing of the traumatic event-neural system, supporting the use of cognitive therapy for post-traumatic symptoms.

RESUMEN

Optic flow provides useful information in service of spatial navigation. However, whether brain networks supporting these two functions overlap is still unclear. Here we used Activation Likelihood Estimation (ALE) to assess the correspondence between brain correlates of optic flow processing and spatial navigation and their specific neural activations. Since computational and connectivity evidence suggests that visual input from optic flow provides information mainly during egocentric navigation, we further tested the correspondence between brain correlates of optic flow processing and that of both egocentric and allocentric navigation. Optic flow processing shared activation with egocentric (but not allocentric) navigation in the anterior precuneus, suggesting its role in providing information about self-motion, as derived from the analysis of optic flow, in service of egocentric navigation. We further documented that optic flow perception and navigation are partially segregated into two functional and anatomical networks, i.e., the dorsal and the ventromedial networks. Present results point to a dynamic interplay between the dorsal and ventral visual pathways aimed at coordinating visually guided navigation in the environment.

Asunto(s)

Mapeo Encefálico , Encéfalo , Flujo Optico , Navegación Espacial , Humanos , Flujo Optico/fisiología , Encéfalo/fisiología , Encéfalo/diagnóstico por imagen , Navegación Espacial/fisiología , Mapeo Encefálico/métodos , Neuroimagen/métodos , Vías Visuales/fisiología , Vías Visuales/diagnóstico por imagen , Percepción Visual/fisiología

RESUMEN

OBJECTIVE: Olfactory dysfunction indicates a higher risk of developing dementia. However, the potential structural and functional changes are still largely unknown. METHODS: A total of 236 participants were enrolled, including 45 Alzheimer's disease (AD) individuals and 191dementia-free individuals. Detailed study methods, comprising neuropsychological assessment and olfactory identification test (University of Pennsylvania smell identification test, UPSIT), as well as structural and functional magnetic resonance imaging (MRI) were applied in this research. The dementia-free individuals were divided into two sub-groups based on olfactory score: dementia-free with olfactory dysfunction (DF-OD) sub-group and dementia-free without olfactory dysfunction (DF-NOD) sub-group. The results were analyzed for subsequent intergroup comparisons and correlations. The cognitive assessment was conducted again three years later. RESULTS: (i) At dementia-free stage, there was a positive correlation between olfactory score and cognitive function. (ii) In dementia-free group, the volume of crucial brain structures involved in olfactory recognition and processing (such as amygdala, entorhinal cortex and basal forebrain volumes) are positively associated with olfactory score. (iii) Compared to the DF-NOD group, the DF-OD group showed a significant reduction in olfactory network (ON) function. (iv) Compared to DF-NOD group, there were significant functional connectivity (FC) decline between PCun_L(R)_4_1 in the precuneus of posterior default mode network (pDMN) and the salience network (SN) in DF-OD group, and the FC values decreased with falling olfactory scores. Moreover, in DF-OD group, the noteworthy reduction in FC were observed between PCun_L(R)_4_1 and amygdala, which was a crucial component of ON. (v) The AD conversion rate of DF-OD was 29.41%, while the DF-NOD group was 12.50%. The structural and functional changes in the precuneus were also observed in AD and were more severe. CONCLUSIONS: In addition to the olfactory circuit, the precuneus is a critical structure in the odor identification process, whose abnormal function underlies the olfactory identification impairment of dementia-free individuals.

Asunto(s)

Enfermedad de Alzheimer , Disfunción Cognitiva , Trastornos del Olfato , Humanos , Olfato , Trastornos del Olfato/diagnóstico por imagen , Cognición , Lóbulo Parietal/diagnóstico por imagen , Imagen por Resonancia Magnética , Disfunción Cognitiva/diagnóstico por imagen , Disfunción Cognitiva/complicaciones

RESUMEN

BACKGROUND: Mid-adolescence is an important phase of self-development in various domains including academics as well as for changes in the neural mechanisms underlying the self-concept. Students' academic self-concept (ASC) is affected by educational achievements and social others (such as teachers and peers). To what extent these external influences relate to neural dynamics during adolescents' self- and other-evaluations (i.e. of friends and teachers) which affect ASC over time is currently unclear. AIMS: The current study aimed to address the question of to what extent the developing ASC is influenced by developmental changes in self- and other-evaluations (friends, teachers) and their underlying neural mechanisms as well as academic achievement. METHODS: In this interdisciplinary longitudinal fMRI study, forty-seven 13-year-olds (at T1) were instructed to indicate whether positive and negative trait adjectives described themselves (self-evaluations), their teachers, or peers (other-evaluations) at two time points. We investigated how adolescents' academic self-concept is influenced by changes in their academic achievement and self- and other-evaluations (teachers and peers) 1.5-years later. RESULTS: Behaviourally, both, academic achievement and positive teacher evaluations were important to prevent the observed decline in ASC during mid-adolescence. Our fMRI results showed that cortical midline structures were linked to self-evaluation, whereas the precuneus and occipital regions were related to friends- and teacher-evaluation. Here, ASC was predicted by activity changes in the precuneus during friends-evaluations for students with better academic achievement. CONCLUSION: Our findings indicate that academic achievement and positive teacher-evaluations could prevent the decline in ASC observed in mid-adolescents and that the neural correlates of evaluating close others within the precuneus present an important link to ASC. The current study highlights the importance of educational neuroscience studies to understand the changing ASC during adolescence.

RESUMEN

Hyperactivation of brain networks conferring defensive mobilization is assumed to underlie inappropriate defensive-preparation in patients with Specific Phobia. However, studies targeting Dental Phobia (DP) yielded quite heterogeneous results and research concerning the effects of exposure treatments on phobic brain activation so far is missing. This functional Magnetic Resonance Imaging (fMRI) study aimed to investigate activation patterns in DP patients during exposure to phobia-related stimuli and the effects of an exposure-based fear treatment on phobia-related activation. Seventeen patients with DP and seventeen non-phobic, healthy controls participated in this fMRI experiment presenting dental-related and neutral auditory and visual stimuli. After completing a short exposure-based CBT program, patients were scanned a second time to illustrate treatment-related changes in brain activation patterns. Pre-treatment fMRI results demonstrate enhanced activation in DP-patients mainly in the precuneus and lateral parietal cortex. Moreover, a small activation focus was observed in the amygdala and anterior cingulate cortex (ACC) as parts of classically fear-related structures. Activation in all these clusters decreased significantly from pre- to post-treatment assessment and in the case of the ACC was correlated with dental fear reduction. Activation changes in the precuneus and lateral parietal cortex suggest a pronounced first-person perspective memory processing including a vivid recall of contextual information from an egocentric perspective triggered by exposure to phobia-related stimuli. Besides a treatment-sensitive hyperactivity of fear-sensitive structures, DP may also be characterized by a disturbed memory retrieval that can be reorganized by successful exposure treatment.

Asunto(s)

Encéfalo , Trastornos Fóbicos , Humanos , Encéfalo/patología , Trastornos Fóbicos/diagnóstico por imagen , Trastornos Fóbicos/terapia , Giro del Cíngulo , Memoria , Amígdala del Cerebelo/patología , Imagen por Resonancia Magnética/métodos , Mapeo Encefálico

RESUMEN

Temporal discounting, the tendency to devalue future rewards as a function of delay until receipt, is influenced by time framing. Specifically, discount rates are shallower when the time at which the reward is received is presented as a date (date condition; e.g., June 8, 2023) rather than in delay units (delay condition; e.g., 30 days), which is commonly referred to as the date/delay effect. However, the cognitive and neural mechanisms of this effect are not well understood. Here, we examined the date/delay effect by analysing combined fMRI and eye-tracking data of N = 31 participants completing a temporal discounting task in both a delay and a date condition. The results confirmed the date/delay effect and revealed that the date condition led to higher fixation durations on time attributes and to higher activity in precuneus/PCC and angular gyrus, that is, areas previously associated with episodic thinking. Additionally, participants made more comparative eye movements in the date compared to the delay condition. A lower date/delay effect was associated with higher prefrontal activity in the date > delay contrast, suggesting that higher control or arithmetic operations may reduce the date/delay effect. Our findings are in line with hypotheses positing that the date condition is associated with differential time estimation and the use of more comparative as opposed to integrative choice strategies. Specifically, higher activity in memory-related brain areas suggests that the date condition leads to higher perceived proximity of delayed rewards, while higher frontal activity (middle/superior frontal gyrus, posterior medial frontal cortex, cingulate) in participants with a lower date/delay effect suggests that the effect is particularly pronounced in participants avoiding complex arithmetic operations in the date condition.

Asunto(s)

Conducta de Elección , Descuento por Demora , Humanos , Imagen por Resonancia Magnética , Tecnología de Seguimiento Ocular , Recompensa

RESUMEN

BACKGROUND: Motor control exercise (MCE) effectively alleviates nonspecific chronic low back pain (CLBP), but the neural mechanisms underlying this phenomenon are poorly understood. OBJECTIVE: To study MCE's neural mechanisms in patients with CLBP by resting-state functional magnetic resonance imaging (rs-fMRI). STUDY DESIGN: A prospective, single-blind, randomized, controlled trial. SETTING: Department of Rehabilitation Medicine, The First Affiliated Hospital, Sun Yat-sen University. METHODS: 58 patients were randomly assigned to either the MCE or the Manual Therapy (MT) group. Before and after treatment, all the patients underwent ultrasound imaging to measure transversus abdominis (TrA) activation, rs-fMRI scans and questionnaire assessments. We analyzed the activation and connectivity of the bilateral precuneus based on the fractional amplitude of low-frequency fluctuation (fALFF) and effective connectivity (EC) analyses. Further, we determined the association between imaging and clinical measures. RESULTS: Pain intensity, pain catastrophizing, and pain-related disability were alleviated significantly in both groups post-treatment. However, the MCE group showed a greater reduction in pain-related disability and a better improvement in activation of the right TrA than the MT group. After MCE, patients showed an increase in regional fALFF values in the key node of the default mode network (bilateral precuneus) and decreased EC from the bilateral precuneus to the key node of the frontoparietal network (the left dorsolateral prefrontal cortex (DLPFC)). The pre-to-post-treatment change in the EC from bilateral precuneus into the left DLPFC was significantly correlated with the pre-to-post-treatment change in visual analog scale scores and activation of the right TrA in the MCE group (r = 0.765, P < 0.001 and r = 0.481 and P = 0.043 respectively). LIMITATIONS: The present study showes the correlation between the alteration of brain functions and CLBP-related symptoms, which does not reveal the causal effect between them. Further, this study does not estimate the long-term efficacy of MCE on brain function, and the sample size was not calculated based on fMRI data. CONCLUSION: These findings demonstrate that MCE may alleviate CLBP symptoms in patients by modifying information transmission from the default mode network to the left frontoparietal network.

Asunto(s)

Dolor de la Región Lumbar , Humanos , Dolor de la Región Lumbar/terapia , Red en Modo Predeterminado , Estudios Prospectivos , Método Simple Ciego , Plasticidad Neuronal

RESUMEN

Procrastination has adverse effects on personal growth and social development. Behavior research has found reward sensitivity is positively correlated with procrastination. However, it remains unclear that the neural substrates underlie the relationship between reward sensitivity and procrastination. To address this issue, the present study used voxel-based morphometry (VBM) and resting-state functional connectivity (RSFC) analyses to investigate the neural substrates underlying the association with reward sensitivity and procrastination in two independent samples (N1 = 388, N2 = 330). In Sample 1, the behavioral result indicated reward sensitivity was positively correlated with procrastination. Moreover, the VBM analysis showed that reward sensitivity was positively associated with the gray matter volume (GMV) of the right parahippocampal gyrus. Furthermore, the RSFC result found reward sensitivity was negatively associated with the functional connectivity of the right parahippocampal gyrus-precuneus. Crucially, the mediation analysis revealed that functional connectivity of the right parahippocampal gyrus-precuneus mediated the relationship between reward sensitivity and procrastination. To verify the robustness of the results, confirmatory analysis was carried out in Sample 2. The results of Sample 1 (i.e., the behavioral, VBM, RSFC, and mediation results) can be verified in Sample 2. In brief, these findings suggested that the functional connectivity of the right parahippocampal gyrus-precuneus involved in reward impulsive control could modulate the relationship between reward sensitivity and procrastination, which is the first to reveal the neural underpinning of the association between reward sensitivity and procrastination.

Asunto(s)

Corteza Prefrontal , Procrastinación , Humanos , Mapeo Encefálico/métodos , Imagen por Resonancia Magnética/métodos , Giro Parahipocampal/diagnóstico por imagen , Sustancia Gris , Lóbulo Parietal/diagnóstico por imagen