Changes in brain connectivity related to the treatment of depression measured through fMRI: a systematic review

Depression is a mental illness that presents alterations in brain connectivity in the Default Mode Network (DMN), the Affective Network (AN) and other cortical-limbic networks, and the Cognitive Control Network (CCN), among others. In recent years the interest in the possible effect of the different antidepressant treatments on functional connectivity has increased substantially. The goal of this paper is to conduct a systematic review of the studies on the relationship between the treatment of depression and brain connectivity. Nineteen studies were found in a systematic review on this topic. In all of them, there was improvement of the clinical symptoms after antidepressant treatment. In 18 out of the 19 studies, clinical improvement was associated to changes in brain connectivity. It seems that both DMN and the connectivity between cortical and limbic structures consistently changes after antidepressant treatment. However, the current evidence does not allow us to assure that the treatment of depression leads to changes in the CCN. In this regard, some papers report a positive correlation between changes in brain connectivity and improvement of depressive symptomatology, particularly when they measure cortical-limbic connectivity, whereas the changes in DMN do not significantly correlate with clinical improvement. Finally, some papers suggest that changes in connectivity after antidepressant treatment might be partly related to the mechanisms of action of the treatment administered. This effect has been observed in two studies with stimulation treatment (one with rTMS and one with ECT), and in two papers that administered three different pharmacological treatments. Our review allows us to make a series of recommendations that might guide future researchers exploring the effect of anti-depression treatments on brain connectivity

Effective connectivity of visual word recognition and homophone orthographic errors

The study of orthographic errors in a transparent language like Spanish is an important topic in relation to writing acquisition. The development of neuroimaging techniques, particularly functional magnetic resonance imaging (fMRI), has enabled the study of such relationships between brain areas. The main objective of the present study was to explore the patterns of effective connectivity by processing pseudohomophone orthographic errors among subjects with high and low spelling skills. Two groups of 12 Mexican subjects each, matched by age, were formed based on their results in a series of ad hoc spelling-related out-scanner tests: a high spelling skills (HSSs) group and a low spelling skills (LSSs) group. During the f MRI session, two experimental tasks were applied (spelling recognition task and visuoperceptual recognition task). Regions of Interest and their signal values were obtained for both tasks. Based on these values, structural equation models (SEMs) were obtained for each group of spelling competence (HSS and LSS) and task through maximum likelihood estimation, and the model with the best fit was chosen in each case. Likewise, dynamic causal models (DCMs) were estimated for all the conditions across tasks and groups. The HSS group's SEM results suggest that, in the spelling recognition task, the right middle temporal gyrus, and, to a lesser extent, the left parahippocampal gyrus receive most of the significant effects, whereas the DCM results in the visuoperceptual recognition task show less complex effects, but still congruent with the previous results, with an important role in several areas. In general, these results are consistent with the major findings in partial studies about linguistic activities but they are the first analyses of statistical effective brain connectivity in transparent languages

Effect of verbal task complexity in a working memory paradigm in patients with type 1 diabetes. A fMRI study.

Podeu consultar dades primàries associades a l'article a: http://hdl.handle.net/2445/109182Type 1 diabetes (T1D) is commonly diagnosed in childhood and adolescence, and the developing brain has to cope with its deleterious effects. Although brain adaptation to the disease may not result in evident cognitive dysfunction, the effects of T1D on neurodevelopment could alter the pattern of BOLD fMRI activation. The aim of this study was to explore the neural BOLD activation pattern in patients with T1D versus that of healthy matched controls while performing two visuospatial working memory tasks, which included a pair of assignments administered through a block design. In the first task (condition A), the subjects were shown a trial sequence of 3 or 4 white squares positioned pseudorandomly around a fixation point on a black background. After a fixed delay, a second corresponding sequence of 3 or 4 red squares was shown that either resembled (direct, 50%) or differed from (50%) the previous stimulation order. The subjects were required to press one button if the two spatial sequences were identical or a second button if they were not. In condition B, the participants had to determine whether the second sequence of red squares appeared in inverse order (inverse, 50%) or not (50%) and respond by pressing a button. If the latter sequence followed an order distinct from the inverse sequence, the subjects were instructed to press a different button. Sixteen patients with normal IQ and without diabetes complications and 16 healthy control subjects participated in the study. In the behavioral analysis, there were no significant differences between the groups in the pure visuo-spatial task, but the patients with diabetes exhibited poorer performance in the task with verbal stimuli (p < .001). However, fMRI analyses revealed that the patients with T1D showed significantly increased activation in the prefrontal inferior cortex, subcortical regions and the cerebellum (in general p < .001). These different activation patterns could be due to adaptive compensation mechanisms that are devoted to improving efficiency while solving more complex cognitive tasks

Neuroimage study on low orthographic competence group

Background: In this paper we studied the functional neural substrates underlying the performance of homophonic spelling error detecting tasks including frequent and infrequent Spanish words- through functional Magnetic Resonance Imaging (fMRI) procedure in subjects with low orthographic performance. Method: A block design was used to administer 2 visual tasks,with 2 experimental conditions each, to 8 healthy participants with low orthographic performance. In both tasks correct and misspelled Spanish words sequentially appeared. Participants were instructed to detect orthographic errorsin one task, as well as the presence of 1 specific vowel in the other. Image data were obtained from 32 axial contiguous slices and repetition time of 3 seconds. Results: Significant bilateral activations were found, especially inmedial temporal areas during the orthographic error recognition task performance, whereas upper right and left frontal regions were significantly activated while detecting a specific vowel. Conclusions: These data are consistent with the literature and suggest an association between orthographic processing and hyperactivation of bilateral cerebral areas in subjects with low orthographic skills, probably due to compensatory mechanism

Radio frequency cooking of pork hams followed with conventional steam cooking

Radio frequency (RF) is a volumetric heating technology that reduces the time needed to cook foodstuffs, but heating is not evenly distributed. The aim of this work was to develop a two-step cooking process in a RF tunnel and in a steam oven (RF-ST) for pork hams and compare it to cooking in a steam oven (ST). The temperature distribution was monitored during cooking and the accumulated lethality was calculated. Cooking losses and physicochemical and sensory properties of the cooked product were analysed. Hot spots and overheating problems were identified during the RF cooking process and were reduced by shielding the ends of the hams with aluminium foil and by adjusting the times of both, RF and steam cooking. The total ST process time (360 min) was reduced by 50% in RF-ST (180 min). Hardly significant differences were observed in the technological and sensory quality of the final product. Regarding the food safety of the RF-ST process, the lowest accumulated lethality in RF-ST process was observed in the outer part of the hams, which can be increased by extending the ST processing time, obtaining a more evenly distributed accumulated lethality in comparison to the ST process.info:eu-repo/semantics/acceptedVersio

Radio frequency cooking of pork hams followed with conventional steam cooking

Radio frequency (RF) is a volumetric heating technology that reduces the time needed to cook foodstuffs, but heating is not evenly distributed. The aim of this work was to develop a two-step cooking process in a RF tunnel and in a steam oven (RF-ST) for pork hams and compare it to cooking in a steam oven (ST). The temperature distribution was monitored during cooking and the accumulated lethality was calculated. Cooking losses and physicochemical and sensory properties of the cooked product were analysed. Hot spots and overheating problems were identified during the RF cooking process and were reduced by shielding the ends of the hams with aluminium foil and by adjusting the times of both, RF and steam cooking. The total ST process time (360 min) was reduced by 50% in RF-ST (180 min). Hardly significant differences were observed in the technological and sensory quality of the final product. Regarding the food safety of the RF-ST process, the lowest accumulated lethality in RF-ST process was observed in the outer part of the hams, which can be increased by extending the ST processing time, obtaining a more evenly distributed accumulated lethality in comparison to the ST process.info:eu-repo/semantics/acceptedVersio

Functional interactions in patients with hemianopia: A graph theory-based connectivity study of resting fMRI signal

Podeu consultar les dades primàries associades a l'article a: http://hdl.handle.net/2445/136617The assessment of task-independent functional connectivity (FC) after a lesion causing hemianopia remains an uncovered topic and represents a crucial point to better understand the neural basis of blindsight (i.e. unconscious visually triggered behavior) and visual awareness. In this light, we evaluated functional connectivity (FC) in 10 hemianopic patients and 10 healthy controls in a resting state paradigm. The main aim of this study is twofold: first of all we focused on the description and assessment of density and intensity of functional connectivity and network topology with and without a lesion affecting the visual pathway, and then we extracted and statistically compared network metrics, focusing on functional segregation, integration and specialization. Moreover, a study of 3-cycle triangles with prominent connectivity was conducted to analyze functional segregation calculated as the area of each triangle created connecting three neighboring nodes. To achieve these purposes we applied a graph theory-based approach, starting from Pearson correlation coefficients extracted from pairs of regions of interest. In these analyses we focused on the FC extracted by the whole brain as well as by four resting state networks: The Visual (VN), Salience (SN), Attention (AN) and Default Mode Network (DMN), to assess brain functional reorganization following the injury. The results showed a general decrease in density and intensity of functional connections, that leads to a less compact structure characterized by decrease in functional integration, segregation and in the number of interconnected hubs in both the Visual Network and the whole brain, despite an increase in long-range inter-modules connections (occipito-frontal connections). Indeed, the VN was the most affected network, characterized by a decrease in intra- and inter-network connections and by a less compact topology, with less interconnected nodes. Surprisingly, we observed a higher functional integration in the DMN and in the AN regardless of the lesion extent, that may indicate a functional reorganization of the brain following the injury, trying to compensate for the general reduced connectivity. Finally we observed an increase in functional specialization (lower between-network connectivity) and in inter-networks functional segregation, which is reflected in a less compact network topology, highly organized in functional clusters. These descriptive findings provide new insight on the spontaneous brain activity in hemianopic patients by showing an alteration in the intrinsic architecture of a large-scale brain system that goes beyond the impairment of a single RSN

Aqueous electrolytes confined within functionalized silica nanopores

Molecular dynamics simulations have been carried out to investigate structural and dynamical characteristics of NaCl aqueous solutions confined within silica nanopores in contact with a “bulk-like” reservoir. Two types of pores, with diameters intermediate between 20 Å and 37.5 Å, were investigated: The first one corresponded to hydrophobic cavities, in which the prevailing wall-solution interactions were of the Lennard-Jones type. In addition, we also examined the behavior of solutions trapped within hydrophilic cavities, in which a set of unsaturated O-sites at the wall were transformed in polar silanol Si–OH groups. In all cases, the overall concentrations of the trapped electrolytes exhibited important reductions that, in the case of the narrowest pores, attained 50% of the bulk value. Local concentrations within the pores also showed important fluctuations. In hydrophobic cavities, the close vicinity of the pore wall was coated exclusively by the solvent, whereas in hydrophilic pores, selective adsorption of Na+ ions was also observed. Mass and charge transport were also investigated. Individual diffusion coefficients did not present large codifications from what is perceived in the bulk; contrasting, the electrical conductivity exhibited important reductions. The qualitative differences are rationalized in terms of simple geometrical considerations.Peer ReviewedPostprint (published version