Primed Low Frequency Transcranial Magnetic Stimulation Effects on Smoking Cue-Induced Craving

Abstract Repetitive Transcranial Magnetic Stimulation (rTMS) has shown the potential to reduce craving to smoke and the amount of cigarettes smoked. When low frequency rTMS is preceded by a priming session the cortical inhibitory effects are enhanced provoking a lasting performance. In this study we evaluate the brain regional activations and self-reported mood effect of one session of primed low frequency rTMS over the left dorsolateral prefrontal cortex (DLPFC) in response to smoking- related cues during temporary nicotine abstinence. Ten moderate nicotine dependent subjects participated in a crossover design, comparing a single session of active versus sham stimulation. After treatment, a functional Magnetic Resonance Imaging (fMRI) study was performed in all participants while completing a block-design cue reactivity paradigm. Our measures also included self-reported craving and mood score before and after every rTMS session. The number of daily smoked cigarette in a one week around period was also recorded. The results show that self-reported cravings were lower following the active stimulation; significant activation was found in areas associated with emotion control (anterior cingulate gyrus and subgenual area) and episodic memory (precuneus and posterior cingulate gyrus) as a result of the stimulation. No significant difference was found in the number of cigarettes smoked and mood scores between the sham and active condition during the one week period records. This study confirms the previous evidence that rTMS can reduce cigarette cravings and provides evidence of the neural mechanism of action that take place in order to achieve these neuromodulation effects.

Resumen La Estimulación Magnética Transcranea repetitiva (EMTr) ha demostrado ser capaz de reducir el deseo por fumar y el consume de cigarrillos. Cuando una baja frecuencia de EMTr es precedida por una sesión de primado, los efectos inhibidores de la corteza cerebral aumentan y también su duración. En este estudio se evalúan las activaciones regionales del cerebro y el efecto en el estado de ánimo auto-reportado de una sesión de EMTr de baja frecuencia primada sobre la corteza dorsolateral prefrontal izquierda en respuesta a estímulos visuales relacionados con el tabaco durante una abstinencia temporal a la nicotina. Diez sujetos con dependencia moderada a la nicotina participaron en un experimento de diseño cruzado, comparando una sola sesión de estimulación activa contra una simulada. Después del tratamiento, se llevó a cabo un estudio de Imagen por Resonancia Magnética funcional (IRMf) en todos los participantes mientras llevaban a cabo un paradigma visual de bloques. Las mediciones incluyeron una puntuación auto-reportada del deseo por fumar y estado de ánimo antes y después de cada sesión de EMTr. Los resultados muestran que el deseo por fumar era menor luego de una sesión activa de estimulación; se encontraron activaciones significativas en áreas asociadas con el control emocional (giro del cíngulo anterior) y memoria episódica (precúneo y giro del cíngulo posterior) como resultado de la estimulación. No se encontró diferencia significativa en el número de cigarros fumados entre la sesión activa y simulado durante el periodo evaluado. Tampoco se registraron diferencias en las evaluaciones de estado de ánimo luego del tratamiento. Este estudio confirma la evidencia previa de que la EMTr puede reducir el deseo por fumar y proporciona evidencia del mecanismo de acción neural que se lleva a cabo para lograr estos efectos neuromoduladores.

Defining new aims for BME programs in Latin America: the case of UAM-Iztapalapa.

The need for upkeep and management of medical technology has fostered the creation of a large number of under graduate programs in the field of biomedical Engineering. In Latin America alone, there are over 85 programs dedicated to this. This contrasts with programs in other regions where most of the undergraduates continue on to pursue graduate degrees or work as research and development engineers in the biomedical industry. In this work we analyze the situation regarding curricular design in the 48 BME programs in Mexico and compare this to suggestions and classifications of programs according to needs and possibilities. We then focus on a particular institution, Universidad Autónoma Metropolitana and due to its characteristics and performance we propose that it should redefine its aims from the undergraduate program on, in order to not only generate research but also to provide a nurturing environment for a budding biomedical industry in Mexico.

Effects of high frequency rTMS on sleep deprivation: A pilot study.

Transcranial magnetic stimulation is a neurostimulation technique which has the potential to serve as a unique research tool for investigating a wide variety of fields in cognitive neuroscience. TMS has been approved by the FDA to serve as a treatment to depression and has also been used to evaluate its effects among several conditions such as Alzheimer, Parkinson disease, chronic pain and stroke. High frequency TMS has been previously used with the intention to measure and modulate the negative effects of sleep deprivation in cognitive performance, but there is no consensus about the ideal protocol yet. In this pilot study, we attempt to test high frequency rTMS in different brain targets in order to determine the effects in remediation of working memory due to sleep deprivation. These results provide preliminary evidence of the potential effectiveness of TMS for the treatment of cognitive impairment.

Effects of Impaired ATP Production and Glucose Sensitivity on Human β-Cell Function: A Simulation Study / Efecto de Alteraciones en la Producción de ATP y la Sensibilidad a la Glucosa en el Funcionamiento de la Célula β Humana: un Estudio de Simulación

In this paper we used a mathematical model to explore the effects of impaired ATP production and glucose sensitivity on the electrical response and insulin secretion of human β-cells. The model was extended by the addition of explicit empirical equations that describe recent experimental observations, namely, the increase of ATP as a function of glucose concentration and the oscillations in ATP at high glucose levels. Simulations were performed at selected glucose concentrations from an oral glucose tolerance test in normal subjects to evaluate the response of the human β-cell in normal and pathological scenarios. Our simulations reproduced experimental observations, such as the impaired insulin secretion as a consequence of β-cell dysfunction and restoration of electrical activity by the use of a sulfonylurea. Our results suggest that both reduced glucose sensitivity and impaired ATP production could be related to the pathogenesis of type 2 diabetes.

En este artículo usamos un modelo matemático para explorar los efectos de alteraciones en la producción de ATP y sensibilidad a la glucosa en la respuesta eléctrica y la secreción de insulina en células β humanas. El modelo fue extendido al añadir ecuaciones empíricas explícitas que describen recientes observaciones experimentales, como el incremento en el ATP como función de la concentración de glucosa y las oscilaciones en el ATP a altos niveles de glucosa. Se realizaron simulaciones a niveles de glucosa alcanzados durante una prueba de tolerancia a la glucosa para evaluar la respuesta de la célula β humana en escenarios normales y patológicos. Nuestras simulaciones reprodujeron varias observaciones experimentales, tales como la secreción de insulina alterada como consecuencia de la disfunción de la célula β y la restauración de la actividad eléctrica al aplicar una sulfonilurea. Nuestros resultados sugieren que tanto una reducción en la sensibilidad a la glucosa como la alteración en la producción de ATP podrían estar relacionadas a la patogénesis de la diabetes tipo 2.

Plugin for OsiriX: mean shift segmentation.

Open source and plugin-based software provide the possibilities for a flexible and free transportation of algorithms to final users. In medical image processing, OsiriX is an instance of the fulfillment of this potential. This work presents the plugin implementation of the mean shift segmentation algorithm. It presents the modeling of the methodology using Object-Oriented tools, as a part of software development process. The resultant models have been represented through Unified Modeling Language (UML). The model parts have been implemented and proved as an OsiriX plugin, helping bridge the divide between algorithms devised in research laboratories and the application of these tools in the clinical setting.

Quantitative and qualitative evaluation of filter characteristics for wavelet packet compression of MR images.

We present an analysis of the characteristics of different filters for the compression of magnetic resonance images. Compression rates were 33:1 and 50:1. We compare the performance among different types of wavelets presented in the literature and provide quantitative (percentage of energy retained, peak signal to noise ratio) and qualitative (analysis by a group of seven experts) data to support our conclusions. Different types of coiflets, symlets and biorthogonal wavelets are analyzed, and we conclude that for the images under study (T1 weighed images in three planes), the best results are provided by the biorthogonal spline (Daubechies) wavelet 2,6. Several explanations for these results are mentioned.

Selection of biorthogonal filters for image compression of MR images using wavelet packets.

We present an analysis of different filter banks for the compression of magnetic resonance (MR) images of the human brain using wavelet packets based on biorthogonal filters. Initially, peak signal to noise ratio (PSNR) and normalized root mean square (RMS) error criteria are calculated for a series of images compressed with a 33:1 ratio, using filter banks based on biorthogonal wavelet packets. The results lead us to choose a few of these filter banks as optimal for image compression. One of these filters is employed to compress several images at four different compression ratios: 12.5:1, 25:1, 37.5:1 and 50:1. The quality of these images was evaluated by visual analysis by a group of seven experts who graded image quality on a 0-7 scale. Results show that using these filters, we can compress images to a rate of around 30:1 without introducing noticeable differences. Other applications for these filters are currently under study and include the compression/fusion of MR image stacks in order to obtain even better reductions in the amount of data needed to reconstruct complete MRI studies.

Effect of static and dynamic exercise on heart rate and blood pressure variabilities.

PURPOSE: This study examines the effect of static and dynamic leg exercises on heart rate variability (HRV) and blood pressure variability (BPV) in humans. METHODS: 10 healthy male subjects were studied at rest, during static exercise performed at 30% of maximal voluntary contraction (SX30), and during dynamic cycling exercises done at 30% of VO2max (DX30) and at 60% of VO2max (DX60). Respiration, heart rate, and blood pressure signals were digitized to analyze temporal and spectral parameters involving short and overall indexes (SD, deltaRANGE, RMSSD, Total power), power of the low (LF), middle (MF), and high (HF) frequency components, and the baroreceptor sensitivity by the alphaMF index. RESULTS: During SX30, indexes of HRV as SD, deltaRANGE, Total power, and MF in absolute units increased in relation with rest values and were significantly higher (P < 0.001) than during DX30 and DX60; HF during SX30, in normalized and absolute units, was not different of the rest condition but was higher (P < 0.001) than HF during DX30 and DX60. Parameters of BPV as SD and deltaRANGE increased (P < 0.001) during both type of exercises, and significant (P < 0.01) increments were observed on MF during SX30 and DX30; systolic HF was attenuated during DX30 (P < 0.05), whereas diastolic HF was augmented during DX60 (P < 0.001). Compared with rest condition, the alphaMF index decreased (P < 0.01) only during dynamic exercises. CONCLUSION: Because HRV and BPV response is different when induced by static or dynamic exercise, differences in the autonomic activity can be advised. Instead of the vagal withdrawal and sympathetic augmentation observed during dynamic exercise, the increase in the overall HRV and the MF component during static exercise suggest an increased activity of both autonomic branches.

The effects of body position, controlled breathing and exercise on the heart rate variability parameters in healthy subjects.

The behavior of temporal and spectral parameters of the heart rate variability was determined during 5 different maneuvers in order to characterize the level of sympathetic-vagal activity. The discriminating capacity of two spectral parameter estimation schemes were compared, and the respiratory influence was evaluated. One hundred and ten records of instantaneous heart rate and respiratory amplitude were analyzed, both in temporal and spectral perspectives. The records were obtained from 22 healthy subjects, under a five-stage protocol: supine, controlled breathing, standing, exercise, and recovery. A discriminating and characteristic behavior was found among the maneuvers, specifically for the dispersion parameters, low and intermediate partial components. The two integration-normalization procedures used in the estimation of the spectral components showed similarities, producing a functional interpretation independent of the selected procedure. The division of the low frequency component in two separate bands, allowed an improved discriminating capacity. The respiration had an important influence in the controlled breathing maneuver while being lower in the rest of the stages. In conclusion, the maneuvers determined a typical behavior of the dispersion and spectral parameters (low and intermediate partial components) of the heart rate variability, showing adequate distinctive levels in the sympathetic-vagal activity for each maneuver.

A multiprocessor architecture for medical image compression in a PACS environment.

We present a new multiprocessor architecture for medical image compression using digital signal processors. The system has been designed to be used in a NuBus-based workstation and to apply different image compression algorithms to medical images. The system has been tested with a full-frame cosine transform and bit allocation table on several imaging modalities ranging from ultrasound to magnetic resonance imaging. Results show that image quality is acceptable when the allocation tables are calculated for each specific image modality. Implementation of algorithms such as wavelet transforms and vector quantization which respond to the characteristics of each type of image is in progress.