Pain Processing in Older Adults and Its Association with Prefrontal Characteristics

Aging is known to affect nociceptive processing, e.g., the ability to inhibit pain. This study aims to investigate whether pain responses in older individuals are associated with prefrontal characteristics, namely (i) executive functioning performance and (ii) structural brain variations in the prefrontal cortex. Heat and pressure stimuli were applied to assess pressure pain sensitivity and endogenous pain inhibition in 46 healthy older individuals. Executive functioning performance was assessed in three domains (i.e., cognitive inhibition, shifting, and updating) and structural brain variations were assessed in both gray and white matter. Overall pain responses were significantly associated with the executive functioning domains cognitive inhibition and shifting. However, no specific type of pain response showed an especially strong association. Endogenous pain inhibition specifically showed a significant association with gray matter volume in the prefrontal cortex and with variations in white matter structure of tracts connecting the prefrontal cortex with the periaqueductal gray. Hierarchical regression analyses showed that these variations in the prefrontal cortex can explain variance in pain inhibition beyond what can be explained by executive functioning. This might indicate that known deficits in pain inhibition in older individuals are associated with structural variations in prefrontal areas

Neural correlates of verbal working memory: an fMRI meta-analysis

Verbal Working memory (vWM) capacity measures the ability to maintain and manipulate verbal information for a short period of time. The specific neural correlates of this construct are still a matter of debate. The aim of this study was to conduct a coordinate-based meta-analysis of 42 fMRI studies on visual vWM in healthy subjects (n=795, males=459, females=325, unknown=11; age range: 18-75). The studies were obtained after an exhaustive literature search on PubMed, Scopus, Web of Science, and Brainmap database. We analyzed regional activation differences during fMRI tasks with the anisotropic effect-size version of seed-based d mapping software (ES-SDM). The results were further validated by performing jackknife sensitivity analyses and heterogeneity analyses. We investigated the effect of numerous relevant influencing factors by fitting corresponding linear regression models. We isolated consistent activation in a network containing fronto-parietal areas, right cerebellum, and basal ganglia structures. Regarding lateralization, the results pointed towards a bilateral frontal activation, a left-lateralization of parietal regions and a right-lateralization of the cerebellum, indicating that the left-hemisphere concept of vWM should be reconsidered. We also isolated activation in regions important for response inhibition, emphasizing the role of attentional control in vWM. Moreover, we found a significant influence of mean reaction time, load and age on activation associated with vWM. Activation in left medial frontal gyrus, left precentral gyrus and left precentral gyrus turned out to be positively associated with mean reaction time whereas load was associated with activation across the PFC, fusiform gyrus, parietal cortex and parts of the cerebellum. In the latter case activation was mainly detectable in both hemispheres whereas the influence of age became manifest predominantly in the left hemisphere. This led us to conclude that future vWM studies should take these factors into consideration

Ventro-striatal/Nucleus accumbens alterations in adult ADHD: effects of pharmacological treatment: a neuroimaging region of interest study

Treball de fi de grau en Biologia HumanaSupervisor: Òscar VilarroyaTutora UPF: Olga ValverdeThe Attention-Deficit/Hyperactivity Disorder (ADHD) is a neuropsychological disorder characterized by inattention, impulsivity and/or hyperactivity. It is one of the most common disorders in childhood with an average prevalence of 5%. Symptoms persist into adulthood in 30-60% of the cases, with 3.4% of the adults maintaining a full-diagnose. Although it is a highly diagnosed disorder, its etiology is still unclear. Currently, the most widely accepted theory points to a dysfunction of the dopamine neurotransmission. ADHD patients present an alteration of the nucleus accumbens (NA). Therefore, this neurostructure is the key target of the pharmacological treatment, mainly Methylphenidate (MPH), which blocks dopamine active transporter (DAT) leading to an increase in dopamine. Despite being the most commonly used pharmacological treatment for ADHD, the neurobiological long-term effects of MPH are poorly understood. Moreover, there is a lack of neuroimaging studies addressing possible changes in brain structure due to pharmacological treatment, especially in adult populations. Therefore, the aim of this study was to apply a ROI analysis to structural magnetic resonance imaging scans to examine whether there were volumetric differences in the nucleus accumbens (NA). The study compared a group of ADHD subjects (n=34) with a group of control subjects (n=33). Addtionally, we studied the NA differences between the sub-group of MPH medicated subjects (n=7) with the sub-group of medication-naïve subjects (n=26). The ADHD group presented a larger NA compared to control group and medicated patients presented a smaller NA compared to non-medicated patients, but none of these differences were statistically significant. It is important to perform more studies with larger and homogeneous samples in order to draw firm conclusions

Ventro-striatal/Nucleus accumbens alterations in adult ADHD: effects of pharmacological treatment: a neuroimaging region of interest study

Treball de fi de grau en Biologia HumanaSupervisor: Òscar VilarroyaTutora UPF: Olga ValverdeThe Attention-Deficit/Hyperactivity Disorder (ADHD) is a neuropsychological disorder characterized by inattention, impulsivity and/or hyperactivity. It is one of the most common disorders in childhood with an average prevalence of 5%. Symptoms persist into adulthood in 30-60% of the cases, with 3.4% of the adults maintaining a full-diagnose. Although it is a highly diagnosed disorder, its etiology is still unclear. Currently, the most widely accepted theory points to a dysfunction of the dopamine neurotransmission. ADHD patients present an alteration of the nucleus accumbens (NA). Therefore, this neurostructure is the key target of the pharmacological treatment, mainly Methylphenidate (MPH), which blocks dopamine active transporter (DAT) leading to an increase in dopamine. Despite being the most commonly used pharmacological treatment for ADHD, the neurobiological long-term effects of MPH are poorly understood. Moreover, there is a lack of neuroimaging studies addressing possible changes in brain structure due to pharmacological treatment, especially in adult populations. Therefore, the aim of this study was to apply a ROI analysis to structural magnetic resonance imaging scans to examine whether there were volumetric differences in the nucleus accumbens (NA). The study compared a group of ADHD subjects (n=34) with a group of control subjects (n=33). Addtionally, we studied the NA differences between the sub-group of MPH medicated subjects (n=7) with the sub-group of medication-naïve subjects (n=26). The ADHD group presented a larger NA compared to control group and medicated patients presented a smaller NA compared to non-medicated patients, but none of these differences were statistically significant. It is important to perform more studies with larger and homogeneous samples in order to draw firm conclusions