Effects of bilingualism on white matter atrophy in mild cognitive impairment: a diffusion tensor imaging study.

BACKGROUND AND PURPOSE: Previous investigations show that bilinguals exhibit the first symptoms of dementia 4-5 years later than monolinguals. Therefore, bilingualism has been proposed as a cognitive reserve mechanism. Recent studies have advanced towards an understanding of the brain mechanisms underlying bilingualism's protection against dementia, but none of them deals with white matter (WM) diffusion. METHODS: In this study, the topic was investigated by measuring WM integrity in a sample of 35 bilinguals and 53 passive bilinguals with mild cognitive impairment. RESULTS: No significant differences were found between the groups in cognitive level, education, age or sex. However, bilinguals showed higher mean diffusivity in the fornix, but higher fractional anisotropy, lower mean diffusivity, axial diffusivity and radial diffusivity in the parahippocampal cingulum, and lower radial diffusivity in the right uncinate fasciculus. Significant correlations were also found between WM integrity in the left parahippocampal cingulum and the Boston Naming Test in passive bilinguals. CONCLUSIONS: These results suggest that bilingualism contributes to a differential pattern of WM disintegration due to mild cognitive impairment in fibers related to bilingualism and memory.

Neural bases of language switching in high and early proficient bilinguals.

The left inferior frontal cortex, the caudate and the anterior cingulate have been proposed as the neural origin of language switching, but most of the studies were conducted in low proficient bilinguals. In the present study, we investigated brain areas involved in language switching in a sample of 19 early, high-proficient Spanish-Catalan bilinguals using a picture naming task that allowed contrasting switch and non-switch trials. Compared to the non-switching condition, language switching elicited greater activation in the head of the left caudate and the pre-SMA/ACC. When the direction of the switching was considered, the left caudate was more associated with forward switching and the pre-SMA/ACC with backward switching. The discussion is focused on the relevance of these brain structures in language control in early, high-proficient bilinguals, and the comparison with previous results in late bilinguals.

Usefulness of Video-EEG monitoring in patients with drug-resistant epilepsy.

OBJECTIVE: To evaluate the characteristics of patients on whom long-term Video-EEG monitoring is performed in a specialist centre and to assess its suitability to study refractory epilepsy patients. METHODS: A prospective analysis and study of Video-EEG monitoring was performed in a series of 100 refractory epilepsy patients from a single centre. The analysis included demographic data, the time until the first seizure, the methods used to provoke seizures, and the outcome (usefulness, change in the management, pharmacological and surgical improvement). A subgroup analysis based on diagnosis was performed. RESULTS: The study was performed mainly on young people (mean 34.4 years) and the first seizure appeared in a mean of 30hours, requiring most of the patients to withdraw the medication. Nevertheless, there were no cases of status epilepticus. The usefulness of the test was high in all the groups. The management was changed in 65% of the patients with pharmacological and surgical improvement. CONCLUSION: Long-term Video-EEG monitoring is a suitable test to study refractory epilepsy patients. The main problem in our country is accesibility.

Bridging language and attention: brain basis of the impact of bilingualism on cognitive control.

Using two languages on an everyday basis appears to have a positive effect on general-purpose executive control in bilinguals. However, the neural correlates of this effect remain poorly understood. To investigate the brain bases of the bilingual advantage in executive control, we tested 21 Spanish monolinguals and 19 Spanish-Catalan early bilinguals in a non-verbal task-switching paradigm. As expected based on previous experiments on non-verbal task switching, we found activation in the right inferior frontal cortex and the anterior cingulate of monolingual participants. While bilingual participants showed a reduced switching cost, they activated the left inferior frontal cortex and the left striatum, a pattern of activation consistent with networks thought to underlie language control. Overall, these results support the hypothesis that bilinguals' early training in switching back and forth between their languages leads to the recruitment of brain regions involved in language control when performing non-linguistic cognitive tasks.

Morphological and functional evaluation of visual disturbances in a bilateral hand allograft recipient.

Allograft recipients are exposed to risks owing to immunosuppression, and there is always the possibility that psychological issues interfere with the procedure's outcomes. An episode of blindness was suspected in a bilateral hand allograft recipient. The patient underwent a multidisciplinary evaluation, and clinical, electrophysiological, laboratory and a combination of functional and morphological magnetic resonance imaging (MRI) tests ruled out any visual process and revealed a secondary benefit, which turned out to be the use of privileges of the transplant support centre for several months. Composite tissue allograft recipients require a thorough psychological assessment before and after transplant procedures to prevent malingering.

Striatum gray matter reduction in males with an overactive behavioral activation system.

Using optimized voxel-based morphometry, we studied the relationship between gray matter volume in brain areas associated with reward and scores on a behavioral activation system measure (the Sensitivity to Reward scale) in a sample of 50 male undergraduates. Voxel-based morphometry analysis revealed a negative correlation between Sensitivity to Reward scores and gray matter volume in the dorsal striatum and prefrontal cortex. Results indicate that a reduced volume in the striatum might be associated with enhanced reward sensitivity and deficits in inhibitory control.

Behavioral Inhibition System activity is associated with increased amygdala and hippocampal gray matter volume: A voxel-based morphometry study.

Recent research has examined anxiety and hyperactivity in the amygdala and the anterior hippocampus while processing aversive stimuli. In order to determine whether these functional differences have a structural basis, optimized voxel-based morphometry was used to study the relationship between gray matter concentration in the brain and scores on a Behavioral Inhibition System measure (the Sensitivity to Punishment scale) in a sample of 63 male undergraduates. Results showed a positive correlation between Sensitivity to Punishment scores and gray matter volume in the amygdala and the hippocampal formation, that is, in areas that Gray, J.A., and McNaughton, N.J. (2000). The neuropsychology of anxiety. Oxford: Oxford Medical Publications. associated with the Behavioral Inhibition System.

Memory lateralization with 2 functional MR imaging tasks in patients with lesions in the temporal lobe.

BACKGROUND: Previous studies to determine memory lateralization with functional MR imaging (fMRI) have used encoding or recall tasks. The convergence between the results of both tasks, however, is unknown. OBJECTIVE: The objective of this study was to investigate hemispheric asymmetries of temporal lobe activity (parahippocampus and fusiform gyri) in patients with temporal lesions by using both kinds of fMRI tasks. METHODS: By using blood oxygenation level-dependent fMRI, hemispheric asymmetries of 25 consecutive patients admitted for presurgical evaluation of memory and 12 healthy control participants were studied. Activation was induced by using the picture-encoding task (processing of complex scenes) and the hometown-walking task (requiring mental navigation through one's hometown by using landmarks given by participants themselves). RESULTS: Results in the control group showed that both tasks activated the parahippocampus similarly. The picture-encoding task, however, yielded greater posterior activations in the parahippocampus than did the hometown-walking task. As observed in other studies, more than half the patients showed contralesional representation of memory in each task. It is important to note that estimated memory lateralization from each task was different in 30% of patients, and several cases showed clear discrepancies between both tasks. CONCLUSION: Although previous studies showed that both tasks were useful for evaluating memory lateralization, the present study suggested that the administration of both tasks is necessary for presurgical evaluation of memory lateralization in patients with lesions in the temporal lobe. Therefore, both encoding and recall processes should at least be considered in the evaluation of memory.

Cortical reorganization during PASAT task in MS patients with preserved working memory functions.

Cortical reorganization in multiple sclerosis (MS) is defined as a compensatory mechanism which requires MS patients to overactivate specific brain areas in order to perform the task as controls. To investigate this process with the Paced Auditory Serial Addition Test (PASAT) task, we selected 15 MS patients who performed the PASAT task within-normal limits and 10 healthy controls. Once selected, we used functional magnetic resonance imaging (fMRI) to investigate brain areas involved in PASAT performance in both groups. Results showed that the task activated the left frontal (BA6 and 9) and parietal cortex (BA7 and 40) in both groups, but MS patients showed a stronger activation in the left prefrontal cortex (BA9, 44 and 45) when compared with controls. These results confirmed those obtained post hoc by Audoin et al. [Audoin, B., Ibarrola, D., Ranjeva, J.P., Confort-Gouny, S., Malikova, I., Ali-Chérif, A.M., Pelletier, J., Cozzone, P., et al., 2003. Compensatory cortical activation observed by fMRI during cognitive task at the earliest stage of MS. Hum. Brain Mapp. 20, 51-58], and we interpreted this as showing true cortical reorganization.

New black blood pulse sequence for studies of the heart.

The black blood concept is based on the signal void principle of the sequences in Spin Echo, SE or FSE, which are very useful for studying the mediastinum and heart. In this setting, new sequences are continuously introduced to eliminate the artifacts caused by breathing and heart movements. One such sequence is the Double-IR preparation Black Blood FSE. We report our experience in 97 patients, using this new pulse sequence to evaluate cardiac pathology, and establish comparisons with the conventional Spin Echo sequences. The study comprises mediastinal disease and aorta and heart explorations. We consider this new Double-IR preparation FSE sequence to be an excellent choice for evaluating chest, mediastinal and cardiac images. The sequence offers improved spatial resolution of both the vessels and other chest structures with respect to conventional Spin Echo imaging. With the exception of patients presenting severe heart problems, or in the presence of intense bradycardia, the required 16 cycles in apnea are well tolerated. The purpose of the present study is to present our initial results with this new pulse sequence as applied to cardiac pathology, in comparison with conventional Spin Echo imaging.

Value of CA 15.3 in breast cancer and comparison with CEA and TPA: a study of specificity in disease-free follow-up patients and sensitivity in patients at diagnosis of the first metastasis.

The specificity and sensitivity of a tumor marker (TM) are important in establishing its potential clinical utility for a specific type of neoplasm. CA 15.3 is a TM specific for breast cancer; it is defined by two monoclonal antibodies (DF3 and 115D8), whose specificity, in disease-free follow-up patients, and sensitivity, in patients at diagnosis of first metastasis, have been evaluated in the present study and compared with those of carcinoembryonic antigen (CEA) and tissue polypeptide antigen (TPA). Serum concentrations of all three TMs were quantified in 618 individuals: 80 healthy controls, 421 patients with local breast cancer who became free of disease following locoregional treatment, and 117 patients with disseminated disease at diagnosis of metastasis. Radioimmunoassay (RIA) was the method employed, and the cut-off values obtained were 30 U/ml for CA 15.3, 5 ng/ml for CEA, and 120 U/I for TPA. The results showed CA 15.3 and CEA specificities to be analogous (95.7 and 95.5%, respectively). TPA specificity (81.9%) was lower (p < 0.001). During adjuvant therapy, CA 15.3 serum levels were seen to increase, followed by a normalization of concentration after terminating therapy. On the other hand, CA 15.3 and TPA sensitivities (64.1 and 67.5%, respectively) were greater than for CEA (44.4%, p < 0.01). It is concluded that CA 15.3 is a useful TM for breast cancer, as it offers a greater sensitivity than CEA and a higher specificity than TPA. Combining CA 15.3 and CEA fails to increase CA 15.3 sensitivity, while combining CA 15.3 with TPA increases false-positives and so likewise offers no additional benefit.

[Diagnostic effectiveness of CT and MR in local staging of renal tumors]. / Eficacia diagnóstica del TC y RM en el estadiaje local de los tumores renales.

The aim of this paper is to study the pre-operative staging of renal tumours, comparing CT and MR, and the imaging criteria used, examining the diagnostic efficacy for each of them. Thirty-four tumours were obtained from 29 patients. All cases were studied with CT and MR. To measure diagnostic efficacy, both for each technique and the criteria used in 2 different readings, a diagnostic performance curve (DPC) is calculated. Neither CT nor MR show infiltration of renal capsule. With regard to perinephritic fat, fascia and adjacent organ invasion, both techniques lead to overstaging, mainly CT. When applying more conservative reading criteria, the results are much improved, specially in relation to CT, although results with MR continue to be more favourable. MR is better to study vascular invasion, providing no false results. Of 22 tumours undergoing surgery, first option was the correct staging in 14 tumour with CT and in 16 with MR. When selecting the best imaging technique to stage renal tumours, MR allows a better and simpler radiologic reading. Nevertheless, considering the high correlation between CT and MR, CT can be used more reliably in institutions where no easy access to a MR unit is available. Both CT and MR overstage renal tumours.

[Irradiation of the thyroid gland: changes in its function]. / Tiroides irradiado: modificaciones de su función

The authors have studied some usual parameters of the evaluation of the thyroid gland function, after secondary irradiation during tele-cobaltherapy treatment in 20 patients with larynx carcinoma. The parameters studied have been iodine uptake, Hamolsky index, T4, FT4 PB127I and cholesterol. The values, statistically treated, enable the conclusion that normal adult thyroid gland has a very low clinical and analytical radiosensibility.