Introducción a las técnicas de neuroimagen

La tomografía por emisión de positrones (PET) y la resonancia magnética (RM) ofrecen la posibilidad de estudiar la anatomía del cerebro y su plasticidad, y de detectar las zonas que se activan o las redes que tienen su actividad sincronizada al realizar determinadas tareas. Se hará una breve introducción de distintas técnicas de neuroimagen con ejemplos de aplicación.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Super-resolution of 3D Magnetic Resonance Images by Random Shifting and Convolutional Neural Networks

Enhancing resolution is a permanent goal in magnetic resonance (MR) imaging, in order to keep improving diagnostic capability and registration methods. Super-resolution (SR) techniques are applied at the postprocessing stage, and their use and development have progressively increased during the last years. In particular, example-based methods have been mostly proposed in recent state-of-the-art works. In this paper, a combination of a deep-learning SR system and a random shifting technique to improve the quality of MR images is proposed, implemented and tested. The model was compared to four competitors: cubic spline interpolation, non-local means upsampling, low-rank total variation and a three-dimensional convolutional neural network trained with patches of HR brain images (SRCNN3D). The newly proposed method showed better results in Peak Signal-to-Noise Ratio, Structural Similarity index, and Bhattacharyya coefficient. Computation times were at the same level as those of these up-to-date methods. When applied to downsampled MR structural T1 images, the new method also yielded better qualitative results, both in the restored images and in the images of residuals.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A reappraisal of echolalia in aphasia: A case-series study with multimodal neuroimaging

Introduction: Verbal echoes are commonplace in patients with aphasia, yet information on their cognitive and neural mechanisms remains unexplored (Berthier et al., in press). This study aims to instantiate the concept of echolalia (Berthier et al., 2016) by reappraising its relevance in the frame of modern neuroscience in three different types: (1) automatic echolalia (AE) (parrot-like repetition of all verbal stimuli); (2) mitigated echolalia (ME) (changes in echoes for communicative purposes), and (3) effortful echolalia (EE) (echolalia with articulatory struggling, distorted prosody, and increased effort). Methods: Case-series study of three variants of echolalia in three patients with chronic post-stroke aphasia using cognitive testing and multimodal imaging including structural magnetic resonance imaging (MRI), diffusion tensor imaging (DTI), functional MRI (fMRI) during repetition of words and non-words, and resting state fMRI (rsfMRI). Patient 1 had mixed transcortical aphasia (mutism and nil auditory comprehension with intact repetition). Patient 2 had residual Wernicke’s aphasia with mildly impaired auditory comprehension; and patient 3 had Broca’s aphasia with impaired syntactic comprehension. Results: Patient 1 had severe AE associated with two large lesions in the left dorsolateral and mesial frontal lobe and the left temporo-parietal cortex (isolation of speech area). DTI revealed absent left dorsal and ventral streams and full development of right white matter tracts. Using fMRI and rsfMRI a compensatory activity in both cerebral hemispheres (right greater than left) was found. Patient 2 had ME associated with DTI-proven incomplete damage to the left dorsal stream and complete damaged to the left ventral stream. fMRI and rsfMRI revealed compensatory activity via right hemisphere structures. Patient 3 had EE associated to a large lesion in the left perisylvian language core. Discussion:Our study revealed heterogeneous aphasic profiles and cognitive deficits in the different types of echolalia amongst patients with chronic aphasia. In addition, multimodal imaging showed a complex pattern of network rearrangement in both cerebral hemispheres which depended upon the localization of the structural lesion. Our preliminary findings set out a starting point to advance research on echolalia eventually providing hints for neurorehabilitation. References: Berthier ML et al.. P. Coppens and J. Patterson (Eds.). Jones & Bartlett Learning, Burlington, MA (2016) Berthier ML et al. Aphasiology (2017)Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Brain Functional Connectivity Is Modified By A Hypocaloric Mediterranean Diet And Physical Activity In Obese Women

Functional magnetic resonance imaging (fMRI) in the resting state has shown altered brain connectivity networks in obese individuals. However, the impact of a Mediterranean diet on cerebral connectivity in obese patients when losing weight has not been previously explored. The aim of this study was to examine the connectivity between brain structures before and six months after following a hypocaloric Mediterranean diet and physical activity program in a group of sixteen obese women aged 46.31 +/- 4.07 years. Before and after the intervention program, the body mass index (BMI) (kg/m(2)) was 38.15 +/- 4.7 vs. 34.18 +/- 4.5 (p < 0.02), and body weight (kg) was 98.5 +/- 13.1 vs. 88.28 +/- 12.2 (p < 0.03). All subjects underwent a pre- and post-intervention fMRI under fasting conditions. Functional connectivity was assessed using seed-based correlations. After the intervention, we found decreased connectivity between the left inferior parietal cortex and the right temporal cortex (p < 0.001), left posterior cingulate (p < 0.001), and right posterior cingulate (p < 0.03); decreased connectivity between the left superior frontal gyrus and the right temporal cortex (p < 0.01); decreased connectivity between the prefrontal cortex and the somatosensory cortex (p < 0.025); and decreased connectivity between the left and right posterior cingulate (p < 0.04). Results were considered significant at a voxel-wise threshold of p <= 0.05, and a cluster-level family-wise error correction for multiple comparisons of p <= 0.05. In conclusion, functional connectivity between brain structures involved in the pathophysiology of obesity ( the inferior parietal lobe, posterior cingulate, temporo-insular cortex, prefrontal cortex) may be modified by a weight loss program including a Mediterranean diet and physical exercise