Accelerated long-term forgetting in resected and seizure-free temporal lobe epilepsy patients

Episodic memory impairments caused by temporal lobe epilepsy (TLE) are well documented in the literature. Standard clinical episodic memory tests typically include a 30-min delayed recall test. However, in the past decade, it has become apparent that this standard test does not capture the full range of memory problems in TLE patients. Some patients perform well on a standard 30-min delayed recall test, but show Accelerated Long-term Forgetting (ALF) after 24 h. Although ALF has been investigated in patients with different types of epilepsy, current research on resected TLE patients is missing. In the present study, resected TLE patients were compared to a control group matched on initial learning. They showed normal performance on verbal recall after 30 min, but impairments became apparent after one week. Moreover, the significant interaction between participant group and memory test delay demonstrated that the patients indeed showed an acceleration in forgetting. Furthermore, ALF was present in both left and right resected TLE patients, which contradicts the presence of material-specific hemispheric differences in ALF. In addition, ALF was observed in seizure-free resected TLE patients, thereby demonstrating that this factor is not crucial for long-term memory deficits. The outcome shows that clinicians are likely to underestimate memory deficits in resected TLE patients and, therefore, advocates for the inclusion of ALF tests in standard clinical batteries for both pre- and post-surgery testing sessions

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

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

A new window to understanding individual differences in reward sensitivity from attentional networks

Existing evidence suggests that the presence of reward cues modifies the activity in attentional networks, however, the nature of these influences remains poorly understood. Here, we performed independent component analysis (ICA) in two fMRI datasets corresponding to two incentive delay tasks, which compared the response to reward (money and erotic pictures) and neutral cues, and yielded activations in the ventral striatum using a general linear model approach. Across both experiments, ICA revealed that both the right frontoparietal network and default mode network time courses were positively and negatively modulated by reward cues, respectively. Moreover, this dual neural response pattern was enhanced in individuals with strong reward sensitivity. Therefore, ICA may be a complementary tool to investigate the relevant role of attentional networks on reward processing, and to investigate reward sensitivity in normal and pathological populations

Inferior frontal cortex activity is modulated by reward sensitivity and performance variability

High reward sensitivity has been linked with motivational and cognitive disorders related with prefrontal and striatal brain function during inhibitory control. However, few studies have analyzed the interaction among reward sensitivity, task performance and neural activity. Participants (N = 57) underwent fMRI while performing a Go/No-go task with Frequent-go (77.5%), Infrequent-go (11.25%) and No-go (11.25%) stimuli. Task-associated activity was found in inhibition-related brain regions, with different activity patterns for right and left inferior frontal gyri (IFG): right IFG responded more strongly to No-go stimuli, while left IFG responded similarly to all infrequent stimuli. Reward sensitivity correlated with omission errors in Go trials and reaction time (RT) variability, and with increased activity in right and left IFG for No-go and Infrequent-go stimuli compared with Frequent-go. Bilateral IFG activity was associated with RT variability, with reward sensitivity mediating this association. These results suggest that reward sensitivity modulates behavior and brain function during executive control.This research has been supported by the Brainglot Project of the 2010 CONSOLIDER-INGENIO Program (CSD2007-00012), and also by grants from MINECO (PSI2012-33054), the Spanish National Drug Strategy (4623/2011), the Spanish Ministry of Health and Consumption, the Generalitat Valenciana (GV/2012/042) and the Universitat Jaume I (P1-1A2010-01) to A. Barrós-Loscertales

Distance disintegration characterizes node-level topological dysfunctions in cocaine addiction

Previous investigations have used global graph theory measures in order to disentangle the complexity of the neural reorganizations occurring in cocaine use disorder (CUD). However, how these global topological alterations map into individual brain network areas remains unknown. In this study, we used resting state functional magnetic resonance imaging (fMRI) data to investigate node-level topological dysfunctions in CUD. The sample was composed of 32 individuals with CUD and 32 healthy controls, matched in age, years of education and intellectual functioning. Graph theory measures of optimal connectivity distance, node strength, nodal efficiency and clustering coefficient were estimated in each participant using voxel-wise functional connectivity connectomes. CUD individuals as compared with healthy controls showed higher optimal connectivity distances in ventral striatum, insula, cerebellum, temporal cortex, lateral orbitofrontal cortex, middle frontal cortex and left hippocampus. Furthermore, clinical measures quantifying severity of dependence were positively related with optimal connectivity distances in the right rolandic operculum and the right lateral orbitofrontal cortex, whereas length of abstinence was negatively associated with optimal connectivity distances in the right temporal pole and the left insula. Our results reveal a topological distancing of cognitive and affective related areas in addiction, suggesting an overall reduction in the communication capacity of these regions.Funding for open access charge: CRUE-Universitat Jaume IThis research was supported by grant 040/2011 from Spanish National Drug Strategy, Ministerio de Sanidad y Consumo to ABL. JAV was supported by a predoctoral graduate programme grant (National FPU). MPG and AMP were supported by a postdoctoral graduate programme grant (postdoc-UJI). VC was supported by grant PID2019-105077RJ-I00 from Ministerio de Ciencia, Innovación y Universidades

Modulación del procesamiento cerebral por la magnitud de la recompensa en tareas de control cognitivo en participantes sanos y adictos a la cocaína

Las contingencias de recompensa además de incrementar la probabilidad de aparición de una conducta y de los procesos cerebrales necesarios para conseguirlas, los optimiza. Esta tesis estudia la modulación producida por la magnitud de la recompensa monetaria sobre el procesamiento cerebral en conductas dirigidas a metas considerando las diferencias individuales en personalidad y la adicción a la cocaína. Se realizaron tres estudios con contingencias monetarias de magnitud variable durante la ejecución de tareas de inhibición en participantes sanos y adictos a la cocaína. La recompensa monetaria produjo una mejora conductual proporcional a la magnitud de recompensa y similar en ambos grupos, asociada en los participantes sanos con las diferencias individuales a la sensibilidad a la recompensa. Sin embargo, los adictos a la cocaína mostraron una modulación prefrontal deficiente que contrarrestaron con una mayor implicación de áreas occipitales, el incremento de la conectividad frontoestriatal y de la red frontoparietal izquierda.Reward contingencies increase the likelihood of a behavior and the brain processes necessary to perform them in addition to optimizing both behavior and brain processes. This doctoral thesis studies the effect of monetary reward magnitude on brain processing during goal-directed behaviors considering individual differences in personality and cocaine addiction. We performed three studies with monetary contingencies of variable magnitude during the execution of inhibition tasks in healthy participants and cocaine addicts. In both groups, the monetary reward produced a behavioral improvement proportional to the magnitude. In addition, in healthy participants this behavioral improvement was associated with the individual differences in sensitivity to reward. However, cocaine addicts showed deficient prefrontal modulation that counteracted with a greater involvement of occipital areas, an increased fronto-striatal connectivity and the left frontoparietal network

BAS-drive trait modulates dorsomedial striatum activity during reward response-outcome associations

According to the Reinforcement Sensitivity Theory, behavioral studies have found that individuals with stronger reward sensitivity easily detect cues of reward and establish faster associations between instrumental responses and reward. Neuroimaging studies have shown that processing anticipatory cues of reward is accompanied by stronger ventral striatum activity in individuals with stronger reward sensitivity. Even though establishing response-outcome contingencies has been consistently associated with dorsal striatum, individual differences in this process are poorly understood. Here, we aimed to study the relation between reward sensitivity and brain activity while processing response-reward contingencies. Forty-five participants completed the BIS/BAS questionnaire and performed a gambling task paradigm in which they received monetary rewards or punishments. Overall, our task replicated previous results that have related processing high reward outcomes with activation of striatum and medial frontal areas, whereas processing high punishment outcomes was associated with stronger activity in insula and middle cingulate. As expected, the individual differences in the activity of dorsomedial striatum correlated positively with BAS-Drive. Our results agree with previous studies that have related the dorsomedial striatum with instrumental performance, and suggest that the individual differences in this area may form part of the neural substrate responsible for modulating instrumental conditioning by reward sensitivity.The project was supported by grants PSI2010-20,168 from Ministerio de Economía y Competitividad, P1•1B2011-09 from the Universitat Jaume I to CA, and grants 040/2011 from Spanish National Drug Strategy Ministerio de Sanidad y Consumo, and PSI2012-33,054 from Ministerio de Economía y Competitividad to ABL

Reward anticipation enhances brain activation during response inhibition

The chance to achieve a reward starts up the required neurobehavioral mechanisms to adapt our thoughts and actions in order to accomplish our objective. However, reward does not equally reinforce everybody but depends on interindividual motivational dispositions. Thus, immediate reward contingencies can modulate the cognitive process required for goal achievement, while individual differences in personality can affect this modulation. We aimed to test the interaction between inhibition-related brain response and motivational processing in a stop signal task by reward anticipation and whether individual differences in sensitivity to reward (SR) modulate such interaction. We analyzed the cognitive–motivational interaction between the brain pattern activation of the regions involved in correct and incorrect response inhibition and the association between such brain activations and SR scores. We also analyzed the behavioral effects of reward on both reaction times for the “go” trials before and after correct and incorrect inhibition in order to test error prediction performance and postinhibition adjustment. Our results show enhanced activation during response inhibition under reward contingencies in frontal, parietal, and subcortical areas. Moreover, activation of the right insula and the left putamen positively correlates with the SR scores. Finally, the possibility of reward outcome affects not only response inhibition performance (e.g., reducing stop signal reaction time), but also error prediction performance and postinhibition adjustment. Therefore, reward contingencies improve behavioral performance and enhance brain activation during response inhibition, and SR is related to brain activation. Our results suggest the conditions and factors that subserve cognitive control strategies in cognitive motivational interactions during response inhibition

Monetary reward magnitude effects on behavior and brain function during goal-directed behavior

Reward may modulate the cognitive processes required for goal achievement, while individual differences in personality may affect reward modulation. Our aim was to test how different monetary reward magnitudes modulate brain activation and performance during goal-directed behavior, and whether individual differences in reward sensitivity affect this modulation. For this purpose, we scanned 37 subjects with a parametric design in which we varied the magnitude of monetary rewards (€0, €0.01, €0.5, €1 or €1.5) in a blocked fashion while participants performed an interference counting-Stroop condition. The results showed that the brain activity of left dorsolateral prefrontal cortex (DLPFC) and the striatum were modulated by increasing and decreasing reward magnitudes, respectively. Behavioral performance improved as the magnitude of monetary reward increased while comparing the non reward (€0) condition to any other reward condition, or the lower €0.01 to any other reward condition, and this improvement was related with individual differences in reward sensitivity. In conclusion, the locus of influence of monetary incentives overlaps the activity of the regions commonly involved in cognitive control