Structural But Not Functional Connectivity Differences within Default Mode Network Indicate Conversion to Dementia

Background:Malfunctioning of the default mode network (DMN) has been consistently related to mild cognitive impairment (MCI) and Alzheimer’s disease (AD). However, evidence on differences in this network between MCI converters (MCI-c) and non-converters (MCI-nc), which could mark progression to AD, is still inconsistent. Objective:To multimodally investigate the DMN in the AD continuum. Methods:We measured gray matter (GM) volume, white matter (WM) integrity, and functional connectivity (FC) at rest in healthy elderly controls, MCI-c, MCI-nc, and AD patients, matched on sociodemographic variables. Results:Significant differences between AD patients and controls were found in the structure of most of the regions of the DMN. MCI-c only differed from MCI-nc in GM volume of the left parahippocampus and bilateral hippocampi and middle frontal gyri, as well as in WM integrity of the parahippocampal cingulum connecting the left hippocampus and precuneus. We found significant correlations between integrity in some of those regions and global neuropsychological status, as well as an excellent discrimination ability between converters and non-converters for the sum of GM volume of left parahippocampus, bilateral hippocampi, and middle frontal gyri, and WM integrity of left parahippocampal cingulum. However, we found no significant differences in FC. Conclusion:These results further support the relationship between abnormalities in the DMN and AD, and suggest that structural measures could be more accurate than resting-state estimates as markers of conversion from MCI to AD

Diferencias anatómicas asociadas a la sensibilidad al castigo y a la recompensa: un estudio de morfometría basada en el vóxel

Introducción: La teoría de la sensibilidad al refuerzo (tsr) propone el sistema de activación conductual (sac) como el sistema motivacional encargado de dirigir la con- ducta hacia la obtención de estímulos apetitivos. A nivel neurobiológico, este sistema se ha relacionado con el circuito cerebral de la recompensa. Así mismo, se ha pro- puesto el rasgo de personalidad de sensibilidad a la recompensa (sr) como modulador de la actividad del sac. En el presente trabajo estudiamos la relación entre la actividad del sac, medida por medio del cuestionario spsrq, y el volumen de sustancia gris en áreas de recompensa. Métodos: Realizamos un análisis de morfometría basada en el vóxel (vbm) en una muestra de 216 hombres e investigamos la asociación entre los valores de volumen obtenidos y las puntuaciones en la escala sr del spsrq mediante un análisis de regresión. El procesado y análisis de las imágenes se realizó mediante spm8. Resultados: A nivel cortical, los análisis de vbm mostraron una correlación ne- gativa entre las puntuaciones de la escala sr y el volumen de sustancia gris en el córtex prefrontal lateral, la ínsula y el lóbulo temporal superior. A nivel subcortical, ob- servamos una reducción en el volumen del estriado (núcleo caudado). Conclusiones: Nuestros resultados apoyan investigaciones previas y aportan nuevas evidencias acerca de las diferencias anatómicas en áreas relacionadas con el control inhibitorio y la toma de decisiones en participantes con un sac sobreactivado.Introduction: The Reinforcement Sensitivity Theory (rst) proposes the Behavioral Activation System (bas) as the motivational system responsible for direct behavior toward appetitive stimuli. Neurobiologically, this system has been related to the brain reward circuitry. Additionally, the personality trait of Sensitivity to Reward (sr) has been proposed as modulator of bas activity. In this work, we studied the relationship between the bas activity, as measured by the spsrq questionnaire, and the gray matter volume in reward-related areas. Methods: We carried out a voxel-based morphometry analysis in a sample of 216 male participants and we investigated the association between the data volume obtained and the sr scale scores by means of a regression analysis. Image processing and statistical analyses were carried out using spm8. Results: At the cortical level, vbm analysis showed a negative correlation between sr scores and the gray matter volume in the lateral prefrontal cortex, the insula, and the superior temporal lobe. Subcortically, we found a reduction in the striatum volume (caudate nucleus). Conclusion: Our results support previous studies and provide new evidence about anatomical differences in brain areas related to inhibitory control and decision-making in participants with an overactive bas

Opening or closing eyes at rest modulates the functional connectivity of V1 with default and salience networks

Current evidence suggests that volitional opening or closing of the eyes modulates brain activity and connectivity. However, how the eye state influences the functional connectivity of the primary visual cortex has been poorly investigated. Using the same scanner, fMRI data from two groups of participants similar in age, sex and educational level were acquired. One group (n = 105) performed a resting state with eyes closed, and the other group (n = 63) performed a resting state with eyes open. Seed-based voxel-wise functional connectivity whole-brain analyses were performed to study differences in the connectivity of the primary visual cortex. This region showed higher connectivity with the default mode and sensorimotor networks in the eyes closed group, but higher connectivity with the salience network in the eyes open group. All these findings were replicated using an open source shared dataset. These results suggest that opening or closing the eyes may set brain functional connectivity in an interoceptive or exteroceptive state

Linking personality and brain anatomy: a structural MRI approach to Reinforcement Sensitivity Theory

Reinforcement Sensitivity Theory (RST) proposes a widely used taxonomy of human personality linked to individual differences at both behavioral and neuropsychological levels that describe a predisposition to psychopathology. However, the body of RST research was based on animal findings, and little is known about their anatomical correspondence in humans. Here we set out to investigate MRI structural correlates (i.e. voxel-based morphometry) of the main personality dimensions proposed by the RST in a group of 400 healthy young adults who completed the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ). Sensitivity to punishment scores correlated positively with the gray matter volume in the amygdala, whereas sensitivity to reward scores correlated negatively with the volume in the left lateral and medial prefrontal cortex. Moreover, a negative relationship was found between the striatal volume and the reward sensitivity trait, but only for male participants. The present results support the neuropsychological basis of the RST by linking punishment and reward sensitivity to anatomical differences in limbic and frontostriatal regions, respectively. These results are interpreted based on previous literature related to externalizing and internalizing disorders, and they highlight the possible role of SPSRQ as a measure of proneness to these disorders

Reward network connectivity “at rest” is associated with reward sensitivity in healthy adults: A resting-state fMRI study

This is a post-peer-review, pre-copyedit version of an article published in Cognitive, Affective, & Behavioral Neuroscience. The final authenticated version is available online at: https://doi.org/10.3758/s13415-019-00688-1.The behavioral approach system (BAS), based on reinforcement sensitivity theory (RST), is a neurobehavioral system responsible for detecting and promoting motivated behaviors towards appetitive stimuli. Anatomically, the frontostriatal system has been proposed as the core of the BAS, mainly the ventral tegmental area and the ventral striatum and their dopaminergic connections with medial prefrontal structures. The RST also proposes the personality trait of reward sensitivity as a measurable construct of stable individual differences in BAS activity. However, the relationship between this trait and brain connectivity “at rest” has been poorly studied, mainly because previous investigations have focused on studying brain activity under reward-related contingency paradigms. Here, we analyzed the influence of reward sensitivity on the resting-state functional connectivity (rs-FC) between BAS-related areas by correlating the BOLD time series with the scores on the Sensitivity to Reward (SR) scale in a sample of 89 healthy young adults. Rs-FC between regions of interest were all significant. Results also revealed a positive association between SR scores and the rs-FC between the VTA and the ventromedial prefrontal cortex, and between the latter structure and the anterior cingulate cortex. These results suggest that reward sensitivity could be associated with different resting-state activity in the mesocortical pathway

Complexity Analysis of Cortical Surface Detects Changes in Future Alzheimer’s Disease Converters

Alzheimer’s disease (AD) is a neurological disorder that creates neurodegenerative changes at several structural and functional levels in human brain tissue. The fractal dimension (FD) is a quantitative parameter that characterizes the morphometric variability of the human brain. In this study we investigate spherical harmonic-based FD (SHFD), thickness and local gyrification index (LGI) to assess whether they identify cortical surface abnormalities toward the conversion to AD. We study 33 AD patients, 122 mild cognitive impairment (MCI) patients (50 MCI-converters and 29 MCI-non converters) and 32 healthy controls (HC). SHFD, thickness and LGI methodology allowed us to perform not only global but also local level assessments in each cortical surface vertex. First, we found that global SHFD decreased in AD and future MCI-converters compared to HC, and in MCI-converters compared to MCI-non-converters. Second, we found that local white matter SHFD was reduced in AD compared to HC and MCI mainly in medial temporal lobe. Third, local white matter SHFD was significantly reduced in MCI-converters compared to MCI-non-converters in distributed areas, including the medial frontal lobe. Thickness and LGI metrics presented a reduction in AD compared to HC. Thickness was significantly reduced in MCI-converters compared to healthy controls in entorhinal cortex and lateral temporal. In summary, SHFD was the only surface measure showing differences between MCI individuals that will convert or remain stable in the next four years. We suggest that SHFD may be an optimal complement to thickness loss analysis in monitoring longitudinal changes in preclinical and clinical stages of AD

Individual differences in the behavioral inhibition system are associated with orbitofrontal cortex and precuneus gray matter volume

The Behavioral Inhibition System (BIS) is described in Gray’s Reinforcement Sensitivity Theory as a hypothetical construct that mediates anxiety in animals and humans. The neuroanatomical correlates of this system are not fully clear, although they are known to involve the amygdala, the septohippocampal system, and the prefrontal cortex. Previous neuroimaging research has related individual differences in BIS with regional volume and functional variations in the prefrontal cortex, amygdala, and hippocampal formation. The aim of the present work was to study BIS-related individual differences and their relationship with brain regional volume. BIS sensitivity was assessed through the BIS/BAS questionnaire in a sample of male participants (N = 114), and the scores were correlated with brain regional volume in a voxel-based morphometry analysis. The results show a negative correlation between the BIS and the volume of the right and medial orbitofrontal cortices and the precuneus. Our results and previous findings suggest that individual differences in anxiety-related personality traits and their related psychopathology may be associated with reduced brain volume in certain structures relating to emotional control (i.e., the orbitofrontal cortex) and self-consciousness (i.e., the precuneus), as shown by our results

Lenguas y psicoterapia: el efecto de la lengua extranjera en la extinción del miedo

Background: Using a foreign language can influence emotion modulation, but whether different psychotherapy processes would be affected by a foreign language is still unclear. The current study explored the foreign language effect on the extinction of fear. Method: During the conditioning phase, part of the neutral stimuli presented to the participants were associated with a threat, while they performed a countdown task in their native language. In the extinction phase, participants performed the same task either in their native/foreign language and were informed that the threat would no longer appear. We collected self-reports of fear, and pupil dilation and electrodermal activity as physiological measures of arousal. Results: Extinction was successful, indicated by greater self-reported fear and pupil dilation during the threat condition compared to neutral in the conditioning phase, but no significant differences during extinction. Although the foreign language group presented higher arousal, fear extinction occurred regardless of the linguistic context. Conclusions: Fear extinction via verbal instructions is equally effective in a foreign and a native language context. These results indicate that evidence should be continue to be gathered on the role of foreign languages using basic paradigms with clinical applications.Antecedentes: Usar un idioma extranjero puede influir la modulación de las emociones, pero no está claro si su uso podría influir diferentes procesos psicoterapéuticos. Este estudio explora el efecto de la lengua extranjera en la extinción del miedo. Método: Durante el condicionamiento, parte de los estímulos presentados se asociaron a amenaza, mientras los participantes realizaban una tarea de cuenta regresiva en un contexto de lengua nativa. En la fase de extinción, se realizó la misma tarea en su lengua nativa/extranjera, y se informó de que ya no habría amenaza. Se recogieron autoinformes de miedo, así como dilatación de pupila y actividad electrodérmica como medidas fisiológicas de excitación. Resultados: La extinción fue satisfactoria, como muestran una mayor dilatación pupilar y los autoinformes de miedo al comparar las condiciones de amenaza y neutral en la fase de condicionamiento, y no encontrar diferencias significativas durante la extinción. Aunque el grupo de lengua extranjera presentó una mayor excitación, la extinción del miedo ocurre independientemente del contexto lingüístico. Conclusiones: La extinción del miedo mediante instrucciones verbales es igualmente eficaz en contexto de lengua extranjera y nativa. Estos resultados invitan a seguir reuniendo pruebas sobre el papel de las lenguas extranjeras mediante paradigmas con aplicaciones clínicas

Actividad cerebral durante la anticipación y la reactividad a imágenes eróticas en función de las diferencias individuales en extraversión

Quinzenes Jornades de Foment de la Investigació de la FCHS (Any 2009-2010

Cambios en el volumen regional de sustancia gris asociados al consumo de tabaco

Setzenes Jornades de Foment de la Investigació (Any 2011)El consumo crónico de tabaco se ha asociado a reducciones en el volumen global del cerebro y a una ejecución más pobre en tareas que implican funciones ejecutivas. En estudios previos, el consumo de tabaco se ha asociado a reducciones en el volumen y la densidad de sustancia gris en regiones prefrontales y el cingulado anterior. El objetivo de este trabajo fue estudiar los cambios en el volumen cerebral regional asociados al consumo de tabaco en población normal. Se adquirieron imágenes anatómicas de resonancia magnética en 3D de todo el cerebro en una muestra de adultos jóvenes (N=63), que fue dividida en dos grupos en función del consumo de tabaco (fumadores y no fumadores). Las imágenes se analizaron mediante morfometría basada en el vóxel, comparando ambos grupos. En el grupo de fumadores, se estudió también el volumen regional de sustancia gris en relación al tiempo de consumo (años de consumo habitual de tabaco) y a la cantidad de cigarrillos consumidos por semana. El grupo de fumadores mostró un menor volumen en el córtex orbitofrontal medial y en el cingulado posterior respecto al grupo de no fumadores. Los años de consumo se asociaron con incrementos de volumen en el lóbulo temporal inferior y con decrementos en el giro frontal superior y el giro frontal medio del hemisferio izquierdo y la ínsula derecha. El número de cigarrillos fumados por semana se asoció a reducciones en el giro precentral y el lóbulo temporal inferior. Estos resultados sugieren la existencia de diferencias en la estructura cerebral entre fumadores y no fumadores en regiones asociadas al control ejecutivo y en otras regiones más directamente asociadas a la conducta adictiva, lo que puede tener implicaciones en el tratamiento del tabaquismo