http://mriquestions.com/uploads/3/4/5/7/34572113/language_review1-s2.0-s1053811912004703-main.pdf

A review and synthesis of the first 20 years of PET and fMRI studies of heard speech, spoken language and reading

In this review of 100 fMRI studies of speech comprehension and production, published in 2009, activation is reported for: prelexical speech perception in bilateral superior temporal gyri; meaningful speech in middle and inferior temporal cortex; semantic retrieval in the left angular gyrus and pars orbitalis; and sentence comprehension in bilateral superior temporal sulci. For incomprehensible sentences, activation increases in four inferior frontal regions, posterior planum temporale, and ventral supramarginal gyrus. These effects are associated with the use of prior knowledge of semantic associations, word sequences, and articulation that predict the content of the sentence. Speech production activates the same set of regions as speech comprehension but in addition, activation is reported for: word retrieval in left middle frontal cortex; articulatory planning in the left anterior insula; the initiation and execution of speech in left putamen, pre-SMA, SMA, and motor cortex; and for suppressing unintended responses in the anterior cingulate and bilateral head of caudate nuclei. Anatomical and functional connectivity studies are now required to identify the processing pathways that integrate these areas to support language.

/pdf/the-anatomy-of-language-a-review-of-100-fmri-studies-5axw9qxeya.pdf

The anatomy of language: a review of 100 fMRI studies published in 2009.

There is considerable interest in the structural and functional properties of the angular gyrus (AG). Located in the posterior part of the inferior parietal lobule, the AG has been shown in numerous meta-analysis reviews to be consistently activated in a variety of tasks. This review discusses the involvement of the AG in semantic processing, word reading and comprehension, number processing, default mode network, memory retrieval, attention and spatial cognition, reasoning, and social cognition. This large functional neuroimaging literature depicts a major role for the AG in processing concepts rather than percepts when interfacing perception-to-recognition-to-action. More specifically, the AG emerges as a cross-modal hub where converging multisensory information is combined and integrated to comprehend and give sense to events, manipulate mental representations, solve familiar problems, and reorient attention to relevant information. In addition, this review discusses recent findings that point to the existence of multiple subdivisions in the AG. This spatial parcellation can serve as a framework for reporting AG activations with greater definition. This review also acknowledges that the role of the AG cannot comprehensibly be identified in isolation but needs to be understood in parallel with the influence from other regions. Several interesting questions that warrant further investigations are finally emphasized.

/pdf/the-angular-gyrus-multiple-functions-and-multiple-4206xtv5tl.pdf

The Angular Gyrus: Multiple Functions and Multiple Subdivisions

Does literacy improve brain function? Does it also entail losses? Using functional magnetic resonance imaging, we measured brain responses to spoken and written language, visual faces, houses, tools, and checkers in adults of variable literacy (10 were illiterate, 22 became literate as adults, and 31 were literate in childhood). As literacy enhanced the left fusiform activation evoked by writing, it induced a small competition with faces at this location, but also broadly enhanced visual responses in fusiform and occipital cortex, extending to area V1. Literacy also enhanced phonological activation to speech in the planum temporale and afforded a top-down activation of orthography from spoken inputs. Most changes occurred even when literacy was acquired in adulthood, emphasizing that both childhood and adult education can profoundly refine cortical organization.

/pdf/how-learning-to-read-changes-the-cortical-networks-for-4nocvxjz3j.pdf

How Learning to Read Changes the Cortical Networks for Vision and Language

Inter-individual variability in perception, thought and action is frequently treated as a source of 'noise' in scientific investigations of the neural mechanisms that underlie these processes, and discarded by averaging data from a group of participants. However, recent MRI studies in the human brain show that inter- individual variability in a wide range of basic and higher cognitive functions — including perception, motor control, memory, aspects of consciousness and the ability to introspect — can be predicted from the local structure of grey and white matter as assessed by voxel-based morphometry or diffusion tensor imaging. We propose that inter-individual differences can be used as a source of information to link human behaviour and cognition to brain anatomy.

/pdf/the-structural-basis-of-inter-individual-differences-in-2fo6a5hcs9.pdf

The structural basis of inter-individual differences in human behaviour and cognition

Language is a uniquely human ability that evolved at some point in the roughly 6,000,000 years since human and chimpanzee lines diverged. Even in the most linguistically impoverished environments, children naturally develop sophisticated language systems. In contrast, reading is a learnt skill that does not develop without intensive tuition and practice. Learning to read is likely to involve ontogenic structural brain changes, but these are nearly impossible to isolate in children owing to concurrent biological, environmental and social maturational changes. In Colombia, guerrillas are re-integrating into mainstream society and learning to read for the first time as adults. This presents a unique opportunity to investigate how literacy changes the brain, without the maturational complications present in children. Here we compare structural brain scans from those who learnt to read as adults (late-literates) with those from a carefully matched set of illiterates. Late-literates had more white matter in the splenium of the corpus callosum and more grey matter in bilateral angular, dorsal occipital, middle temporal, left supramarginal and superior temporal gyri. The importance of these brain regions for skilled reading was investigated in early literates, who learnt to read as children. We found anatomical connections linking the left and right angular and dorsal occipital gyri through the area of the corpus callosum where white matter was higher in late-literates than in illiterates; that reading, relative to object naming, increased the interhemispheric functional connectivity between the left and right angular gyri; and that activation in the left angular gyrus exerts top-down modulation on information flow from the left dorsal occipital gyrus to the left supramarginal gyrus. These findings demonstrate how the regions identified in late-literates interact during reading, relative to object naming, in early literates.

An anatomical signature for literacy

La importancia de las imagenes diagnosticas en la evaluacion del TCE radica en la deteccion temprana de lesiones y complicaciones permitiendo su tratamiento oportuno, reduciendo el numero de muertes, secuelas y costos. Tambien permite fijar pronostico y realizar seguimiento de los pacientes.

/pdf/actualizaciones-en-radiologia-papel-de-las-imagenes-3sfojwzf7j.pdf

Actualizaciones en radiología. Papel de las imágenes diagnósticas en la valoración del trauma craneoencefálico

We performed a review of  literature on CNS involvement in AIDS patients. Besides several cases seen in Hospital San Juan de Dios in Bogota, Colombia, are illustrated with tomographic images We propose an algorithmic decision tree in the patient with AIDS and neurologic symptoms.

/pdf/neuroimagen-de-la-toxoplasmosis-en-el-paciente-con-sida-1mb5hpphmm.pdf

Neuroimagen de la toxoplasmosis en el paciente con Sida

/pdf/analisis-de-espectros-de-resonancia-magnetica-cjttmi9whw.pdf

Alfonso Javier Lozano

Papers

An anatomical signature for literacy

Actualizaciones en radiología. Papel de las imágenes diagnósticas en la valoración del trauma craneoencefálico

Neuroimagen de la toxoplasmosis en el paciente con Sida

Análisis de espectros de resonancia magnética