Publications by authors named "Helena Melero"

11 Publications

  • Page 1 of 1

Effects of perinatal HIV-infection on the cortical thickness and subcortical gray matter volumes in young adulthood.

Medicine (Baltimore) 2021 Apr;100(15):e25403

Paediatric Infectious Diseases Department, Hospital Universitario 12 De Octubre, Madrid, Madrid, Spain.

Abstract: Brain atrophy has been observed in perinatally HIV-infected patients (PHIV) despite initiation on combined antiretroviral treatment (cART), but neuroimaging studies are limited. We aimed to evaluate cortical thickness (CT) and subcortical gray matter (GM) volumes of PHIV youths with stable immunovirological situation and with a normal daily performance.A prospective cross-sectional study was conducted. A total of 25 PHIV patients on cART and 25 HIV-negative (HIV-) controls matched by age, sex, level of education, and socioeconomic status underwent a magnetic resonance imaging scan. CAT12 toolbox was used to extract CT values from T1w images using parcellations from Desikan-Killiany atlas (DK40). To measure regional brain volumes, native segmented images were parceled in regions of interest according to the Neuromorphometrics Atlas. Neuropsychological assessment and psychopathological symptoms were documented.Fifty participants were included (60% females, median age 20 years [interquartile range, IQR 19-23], 64% Whites). No differences regarding neuropsychological tests or psychopathological symptoms were found between groups (all P > .05). All participants presented an average performance in the Fluid Intelligence (FI) test (PHIV mean: -0.12, HIV- mean: 0.24), When comparing CT, PHIV-infected patients showed thinner cortices compared with their peers in fusiform gyrus (P = .000, P = .009), lateral-orbitofrontal gyrus (P = .006, P = .0024), and right parsobitalis gyrus (P = .047). Regarding subcortical GM volumes, PHIV patients showed lower right amygdala (P = .014) and left putamen (P = .016) volumes when compared with HIV- controls. Within the PHIV group, higher CD4 count was associated with higher volumes in right putamen (B = 0.00000038, P = .045). Moreover, increased age at cART initiation and lower nadir CD4 count was associated with larger volumes in left accumbens (B = 0.0000046, P = .033; B = -0.00000008, P = .045, respectively).PHIV patients showed thinner cortices of areas in temporal, orbito-frontal and occipital lobes and lower volumes of subcortical GM volumes when compared with the HIV- control group, suggesting cortical and subcortical brain alterations in otherwise neuroasymptomatic patients. Nevertheless, larger and longitudinal studies are required to determine the impact of HIV on brain structure in PHIV patients and to further identify risk and protective factors that could be implicated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/MD.0000000000025403DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8051971PMC
April 2021

A Systematic Review of Magnetic Resonance Imaging Studies in Perinatally HIV-Infected Individuals.

AIDS Rev 2021 Mar 18. Epub 2021 Mar 18.

Paediatric Infectious Diseases Department, Hospital Universitario 12 De Octubre and NeuroCoRISpe Project, included in CoRIspe (Spanish National Cohort of Paediatric HIV), Madrid, Spain.

Over the past few years, neuroimaging studies have been performed in young adults with perinatally acquired HIV (PHIV) to study the impact of HIV infection on the central nervous system (CNS), but no recent review have been published. This review aims to identify brain areas where PHIV eems to have greater impact taking into account demographic, behavioral, and clinical characteristics in PHIV infected patients. For this purpose, PubMed and Medline searches were carried out which included studies from 2010 to April 2020. We performed a systematic review and included 26 articles using structural (brain morphometry and diffusion tensor imaging) and functional magnetic resonance imaging methods involving 1182 PHIV-infected participants. Ample evidence has been provided of HIV effects on underlying brain structure. However, information recorded in the studies is commonly incomplete and results sometimes contradictory. In addition to future improvements and dissemination of tools for the developing brain MRI processing and analysis, the inclusion of data related to HIV infection itself (including clinical and immunovirological characteristics as well as detailed information about antiretroviral treatment such as age at ART initiation) may be of vital importance to the better understanding of the impact of the disease on CNS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.24875/AIDSRev.20000088DOI Listing
March 2021

The interplay between functioning problems and symptoms in first episode of psychosis: An approach from network analysis.

J Psychiatr Res 2021 04 15;136:265-273. Epub 2021 Feb 15.

Department of Psychiatry, Hospital Universitario de La Princesa, Instituto de Investigación Sanitaria del Hospital Universitario de La Princesa, IIS Princesa, CIBERSAM, School of Medicine, Universidad Autónoma de Madrid, Madrid, Spain. Electronic address:

The relationship between psychotic symptoms and global measures of functioning has been widely studied. No previous study has assessed so far the interplay between specific clinical symptoms and particular areas of functioning in first-episode psychosis (FEP) using network analysis methods. A total of 191 patients with FEP (age 24.45 ± 6.28 years, 64.9% male) participating in an observational and longitudinal study (AGES-CM) comprised the study sample. Functioning problems were assessed with the WHO Disability Assessment Schedule (WHODAS), whereas the Positive and Negative Syndrome Scale (PANSS) was used to assess symptom severity. Network analysis were conducted with the aim of analysing the patterns of relationships between the different dimensions of functioning and PANSS symptoms and factors at baseline. According to our results, the most important nodes were "conceptual disorganization", "emotional withdrawal", "lack of spontaneity and flow of conversation", "delusions", "unusual thought content", "dealing with strangers" and "poor rapport". Our findings suggest that these symptoms and functioning dimensions should be prioritized in the clinical assessment and management of patients with FEP. These areas may also become targets of future early intervention strategies, so as to improve quality of life in this population.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jpsychires.2021.02.024DOI Listing
April 2021

Variability in the analysis of a single neuroimaging dataset by many teams.

Nature 2020 06 20;582(7810):84-88. Epub 2020 May 20.

Department of Psychology, Rutgers University-Newark, Newark, NJ, USA.

Data analysis workflows in many scientific domains have become increasingly complex and flexible. Here we assess the effect of this flexibility on the results of functional magnetic resonance imaging by asking 70 independent teams to analyse the same dataset, testing the same 9 ex-ante hypotheses. The flexibility of analytical approaches is exemplified by the fact that no two teams chose identical workflows to analyse the data. This flexibility resulted in sizeable variation in the results of hypothesis tests, even for teams whose statistical maps were highly correlated at intermediate stages of the analysis pipeline. Variation in reported results was related to several aspects of analysis methodology. Notably, a meta-analytical approach that aggregated information across teams yielded a significant consensus in activated regions. Furthermore, prediction markets of researchers in the field revealed an overestimation of the likelihood of significant findings, even by researchers with direct knowledge of the dataset. Our findings show that analytical flexibility can have substantial effects on scientific conclusions, and identify factors that may be related to variability in the analysis of functional magnetic resonance imaging. The results emphasize the importance of validating and sharing complex analysis workflows, and demonstrate the need for performing and reporting multiple analyses of the same data. Potential approaches that could be used to mitigate issues related to analytical variability are discussed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41586-020-2314-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7771346PMC
June 2020

Real-time fMRI feedback impacts brain activation, results in auditory hallucinations reduction: Part 1: Superior temporal gyrus -Preliminary evidence.

Psychiatry Res 2020 Feb 10;286:112862. Epub 2020 Feb 10.

Harvard Medical School, Boston, MA 02115, USA; Boston VA Healthcare System, Boston, MA 02130, USA; Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.

Auditory hallucinations (AH) are one of the core symptoms of schizophrenia (SZ) and constitute a significant source of suffering and disability. One third of SZ patients experience pharmacology-resistant AH, so an alternative/complementary treatment strategy is needed to alleviate this debilitating condition. In this study, real-time functional Magnetic Resonance Imaging neurofeedback (rt-fMRI NFB), a non-invasive technique, was used to teach 10 SZ patients with pharmacology-resistant AH to modulate their brain activity in the superior temporal gyrus (STG), a key area in the neurophysiology of AH. A functional task was designed in order to provide patients with a specific strategy to help them modify their brain activity in the desired direction. Specifically, they received neurofeedback from their own STG and were trained to upregulate it while listening to their own voice recording and downregulate it while ignoring a stranger's voice recording. This guided performance neurofeedback training resulted in a) a significant reduction in STG activation while ignoring a stranger's voice, and b) reductions in AH scores after the neurofeedback session. A single, 21-minute session of rt-fMRI NFB was enough to produce these effects, suggesting that this approach may be an efficient and clinically viable alternative for the treatment of pharmacology-resistant AH.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.psychres.2020.112862DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7808413PMC
February 2020

Real-time fMRI neurofeedback reduces auditory hallucinations and modulates resting state connectivity of involved brain regions: Part 2: Default mode network -preliminary evidence.

Psychiatry Res 2020 02 14;284:112770. Epub 2020 Jan 14.

Department of Brain and Cognitive Sciences and McGovern Institute for Brain Research, Massachusetts Institute of Technology. Cambridge, MA 02139, USA; Northeastern University, Boston, MA 02139, USA.

Auditory hallucinations (AHs) are one of the most distressing symptoms of schizophrenia (SZ) and are often resistant to medication. Imaging studies of individuals with SZ show hyperactivation of the default mode network (DMN) and the superior temporal gyrus (STG). Studies in SZ show DMN hyperconnectivity and reduced anticorrelation between DMN and the central executive network (CEN). DMN hyperconnectivity has been associated with positive symptoms such as AHs while reduced DMN anticorrelations with cognitive impairment. Using real-time fMRI neurofeedback (rt-fMRI-NFB) we trained SZ patients to modulate DMN and CEN networks. Meditation is effective in reducing AHs in SZ and to modulate brain network integration and increase DMN anticorrelations. Consequently, patients were provided with meditation strategies to enhance their abilities to modulate DMN/CEN. Results show a reduction of DMN hyperconnectivity and increase in DMNCEN anticorrelation. Furthermore, the change in individual DMN connectivity significantly correlated with reductions in AHs. This is the first time that meditation enhanced through rt-fMRI-NFB is used to reduce AHs in SZ. Moreover, it provides the first empirical evidence for a direct causal relation between meditation enhanced rt-fMRI-NFB modulation of DMNCEN activity and post-intervention modulation of resting state networks ensuing in reductions in frequency and severity of AHs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.psychres.2020.112770DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7046150PMC
February 2020

Graph theory analysis of resting-state functional magnetic resonance imaging in essential tremor.

Hum Brain Mapp 2019 11 22;40(16):4686-4702. Epub 2019 Jul 22.

Medical Image Analysis Laboratory (LAIMBIO), Rey Juan Carlos University, Madrid, Spain.

Essential tremor (ET) is a neurological disease with both motor and nonmotor manifestations; however, little is known about its underlying brain basis. Furthermore, the overall organization of the brain network in ET remains largely unexplored. We investigated the topological properties of brain functional network, derived from resting-state functional magnetic resonance imaging (MRI) data, in 23 ET patients versus 23 healthy controls. Graph theory analysis was used to assess the functional network organization. At the global level, the functional network of ET patients was characterized by lower small-worldness values than healthy controls-less clustered functionality of the brain. At the regional level, compared with the healthy controls, ET patients showed significantly higher values of global efficiency, cost and degree, and a shorter average path length in the left inferior frontal gyrus (pars opercularis), right inferior temporal gyrus (posterior division and temporo-occipital part), right inferior lateral occipital cortex, left paracingulate, bilateral precuneus bilaterally, left lingual gyrus, right hippocampus, left amygdala, nucleus accumbens bilaterally, and left middle temporal gyrus (posterior part). In addition, ET patients showed significant higher local efficiency and clustering coefficient values in frontal medial cortex bilaterally, subcallosal cortex, posterior cingulate cortex, parahippocampal gyri bilaterally (posterior division), right lingual gyrus, right cerebellar flocculus, right postcentral gyrus, right inferior semilunar lobule of cerebellum and culmen of vermis. Finally, the right intracalcarine cortex and the left orbitofrontal cortex showed a shorter average path length in ET patients, while the left frontal operculum and the right planum polare showed a higher betweenness centrality in ET patients. In conclusion, the efficiency of the overall brain functional network in ET is disrupted. Further, our results support the concept that ET is a disorder that disrupts widespread brain regions, including those outside of the brain regions responsible for tremor.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/hbm.24730DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6865733PMC
November 2019

Relationship between episodic memory and volume of the brain regions of two functional cortical memory systems in multiple sclerosis.

J Neurol 2018 Oct 11;265(10):2182-2189. Epub 2018 Jul 11.

Multiple Sclerosis Unit, Department of Neurology, Getafe University Hospital, European University of Madrid, Carretera de Toledo km 12,5, 28905, Madrid, Spain.

Background/objective: Two functional networks are proposed as neuronal support for the complex processes of memory: the anterior temporal and the medial posterior systems. We examined the atrophy of hippocampus (HC) and of those areas constituting the two functional memory systems in multiple sclerosis (MS) patients with low disability.

Methods: Episodic memory (EM) was assessed in 88 relapsing MS patients and in 40 healthy controls using Wechsler Memory Scale III (Spanish adaptation). FreeSurfer software was used to calculate normalized volume of total cortex, grey matter, white matter, subcortical grey matter (thalamus and striatum), HC and both the anterior temporal (entorhinal, ventral temporopolar, lateral orbitofrontal, amygdala) and posterior medial systems (thalamus, parahippocampal, posterior cingulate, precuneus, lateral parietal and medial prefrontal). Linear regression analysis was used to identify predictors of memory performance.

Results: Total grey matter and cortex volumes correlated with all subtypes of EM, and the precuneus volume correlated with overall, immediate and delayed memories. Univariant regression analysis identified an association between the volumes of the posterior medial memory network regions and EM scores. The volume of the left precuneus area was the unique and independent predictor for all EM subtypes except for visual memory, for which left HC volume was also an independent predictor.

Conclusion: Left precuneus volume was the best predictor of memory in relapsing MS patients with low disability and mild deficits in EM.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00415-018-8965-xDOI Listing
October 2018

Why is the synesthete's "A" red? Using a five-language dataset to disentangle the effects of shape, sound, semantics, and ordinality on inducer-concurrent relationships in grapheme-color synesthesia.

Cortex 2018 02 14;99:375-389. Epub 2017 Dec 14.

Department of Psychology, University of California, San Diego, San Diego, CA, USA.

Grapheme-color synesthesia is a neurological phenomenon in which viewing a grapheme elicits an additional, automatic, and consistent sensation of color. Color-to-letter associations in synesthesia are interesting in their own right, but also offer an opportunity to examine relationships between visual, acoustic, and semantic aspects of language. Research using large populations of synesthetes has indeed found that grapheme-color pairings can be influenced by numerous properties of graphemes, but the contributions made by each of these explanatory factors are often confounded in a monolingual dataset (i.e., only English-speaking synesthetes). Here, we report the first demonstration of how a multilingual dataset can reveal potentially-universal influences on synesthetic associations, and disentangle previously-confounded hypotheses about the relationship between properties of synesthetic color and properties of the grapheme that induces it. Numerous studies have reported that for English-speaking synesthetes, "A" tends to be colored red more often than predicted by chance, and several explanatory factors have been proposed that could explain this association. Using a five-language dataset (native English, Dutch, Spanish, Japanese, and Korean speakers), we compare the predictions made by each explanatory factor, and show that only an ordinal explanation makes consistent predictions across all five languages, suggesting that the English "A" is red because the first grapheme of a synesthete's alphabet or syllabary tends to be associated with red. We propose that the relationship between the first grapheme and the color red is an association between an unusually-distinct ordinal position ("first") and an unusually-distinct color (red). We test the predictions made by this theory, and demonstrate that the first grapheme is unusually distinct (has a color that is distant in color space from the other letters' colors). Our results demonstrate the importance of considering cross-linguistic similarities and differences in synesthesia, and suggest that some influences on grapheme-color associations in synesthesia might be universal.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.cortex.2017.12.003DOI Listing
February 2018

[Colors, tastes, numbers?: synesthesia in a Spanish sample].

Rev Neurol 2015 Feb;60(4):145-50

Universidad Complutense de Madrid, Somosaguas, Espana.

Introduction: Synesthesia is a neural phenomenon in which stimulation in one sensory or cognitive stream leads to associated experiences in a second, unstimulated stream. These activations occur involuntarily, automatically and consistently over time.

Aim: To estimate the relative frequency of the different modalities of the phenomenon in a Spanish sample.

Subjects And Methods: Study performed in educational (55.04%), labor (20.54%) and digital contexts (24.4%) using the Synesthesia Questionnaire created by Artecitta Foundation.

Results: The analysis of the responses given by 803 participants suggests that 13.95% of the sample experience any synesthesia. The analysis of the relative frequencies shows that the most frequent modality is spatial sequence synesthesia (44.6%). 33.9% see colors when listening to sounds and/or music, 25.9% associate colors to temporal concepts, 20.5% assign gender and personality to letters and numbers, 10.7% experience grapheme-color synesthesia and 5.4% feel a specific flavor when hearing words.

Conclusions: These data suggest that the presence of synesthesia in the Spanish sample under study is high, and that the investigation of the phenomenon and its different modalities needs to be approached on the basis of the current knowledge about its phenomenological variability and its genetic and neurophysiologic characteristics. Likewise, the results are useful to adjust the questionnaire items and increase their discriminative power.
View Article and Find Full Text PDF

Download full-text PDF

Source
February 2015

Grapheme-color synesthetes show peculiarities in their emotional brain: cortical and subcortical evidence from VBM analysis of 3D-T1 and DTI data.

Exp Brain Res 2013 Jun 19;227(3):343-53. Epub 2013 Apr 19.

Departamento de Psicobiología, Facultad de Psicología, Universidad Complutense de Madrid, Madrid, Spain.

Grapheme-color synesthesia is a neurological phenomenon in which viewing achromatic letters/numbers leads to automatic and involuntary color experiences. In this study, voxel-based morphometry analyses were performed on T1 images and fractional anisotropy measures to examine the whole brain in associator grapheme-color synesthetes. These analyses provide new evidence of variations in emotional areas (both at the cortical and subcortical levels), findings that help understand the emotional component as a relevant aspect of the synesthetic experience. Additionally, this study replicates previous findings in the left intraparietal sulcus and, for the first time, reports the existence of anatomical differences in subcortical gray nuclei of developmental grapheme-color synesthetes, providing a link between acquired and developmental synesthesia. This empirical evidence, which goes beyond modality-specific areas, could lead to a better understanding of grapheme-color synesthesia as well as of other modalities of the phenomenon.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00221-013-3514-4DOI Listing
June 2013