Respiratory and non respiratory oscillations of the skin blood flow: a window to the function of the sympathetic fibers to the skin blood vessels

OBJECTIVE OF THE STUDY: The skin blood flow (SBF) has been known to oscillate in frequency and amplitude. The nature and type of these oscillations have remained obscure. We studied the oscillations of the SBF in frequency and amplitude with non invasive techniques during normal breathing at rest and compared it to the oscillations during rhythmic paced breathing at 6 cycles per minute. SUBJECTS AND METHODS: Thirty healthy subjects were studied under normothermic conditions. The following variables were recorded: 1) EKG signal; 2) SBF signal given by an infrared photoplethysmograph; 3) respiratory movements (RM). A correlation of the frequency of the respiration, the SBF and the EKG was made. The variability of the amplitudes of the SBF, RR intervals and pulse intervals was analyzed in the time domain and with spectral analysis using Fourier analysis. RESULTS: We found no clear respiratory modulation of the amplitude of the SBF during natural breathing at rest. With default breathing there was a low frequency oscillations (LF 0.04 to 0.15 Hz) modulation of the amplitude of the SBF that was non respiratory in nature. During rhythmic breathing at 0.1 Hz there was a strong modulation at LF of the SBF with a typical waxing and waning appearance, decreasing in amplitude during the tachycardia period and increasing in amplitude during the bradycardia period. CONCLUSIONS: Under normothermic conditions there is a consistent variability of the frequency and amplitude of the SBF with normal and rhythmic breathing. While breathing at rest the modulation of SBF amplitude was clearly seen at LF and non respiratory related. With rhythmic breathing there is a strong modulation of amplitude and frequency at the respiratory frequency.

Thinner abuse alters peak of frequency of EEG spectra analyses / El abuso de tíner altera el pico de frecuencia del análisis espectral del EEG

STUDY OBJECTIVE: The aim of the investigation was to use electroencephalography (EEG) to study whether long-term thinner abuse may result in the slowing, disorganization and asymmetry of the EEG cortical rhythms. METHOD: Twenty-two patients attending with antecedent of thinner abuse only, and twenty two controls without alcohol, smoking, and drug abuse in the same age range and gender were studied. EEG recording were compared by means of the analyses of peak of frequency (POF), frequency of disorganization, and asymmetry of the background activity in patients and controls at rest eyes-closed condition in electrodes P3, P4, O1, and O2. RESULTS: Significant differences in POF among groups was observed in P3 and P4 location showing lower values in thinner abusers, but not in O1 and O2 locations. Frequencies of disorganization and asymmetry showed significantly higher proportions in thinner abusers. Bivariate correlations among POF at the four electrode location and time of thinner abuse showed significant values. However after partial correlation calculation correcting for age, significant values disappeared. CONCLUSION: Thus thinner abuse relates with slowing of POF in the EEG of patients with thinner abuse associated with disorganization, and asymmetry depending on time of abuse.

OBJETIVO: Utilizar el electroencefalograma (EEG) para estudiar si el abuso o intoxicación crónica por tíner produce lentificación, desorganización y asimetría de la actividad eléctrica cortical. MÉTODO: Se estudiaron 22 pacientes con antecedentes de intoxicación crónica por tíner y 22 sujetos sin antecedentes de abuso de tíner, alcohol, cigarro o drogas en el mismo rango de edad y en igual número de acuerdo al género. Se registro el EEG cuantitativo y se compararon: el promedio del pico de frecuencia (PoF), la frecuencia de desorganización de la actividad de fondo y la presencia de asimetría inter-hemisférica en la condición de reposo físico y mental entre las regiones de los electrodos P3, P4, O1 y O2. RESULTADOS: Se encontraron diferencias significativas en el PoF entre los grupo estudiados en P3 y P4 observándose valores menores en el grupo con antecedente de intoxicación crónica con tíner, sin embargo estas diferencias no fueron observadas en O1 y O2. La frecuencia de desorganización y de asimetría fue mayor entre los pacientes con antecedente de intoxicación crónica con tíner. Las correlaciones bivariadas entre el PoF en las cuatro localizaciones y el tiempo de consumo de tíner mostraron valores significativos, sin embargo, cuando fueron corregidas por la edad desaparecieron. CONCLUSION: La intoxicación crónica por tíner se relaciona a una lentificación del PoF del EEG de estos pacientes asociada con desorganización y asimetría que dependen parcialmente del tiempo de consumo.

Characteristics of specific reading disability in children from a neuropsychological clinic in Mexico City

OBJECTIVE: This report describes the main clinical features associated with specific reading disability (RD) in a group of 778 school-age children studied in a Neuropsychological Clinic in Mexico City. MATERIAL AND METHODS: The study was performed retrospectively, using data abstracted from clinical records of subjects seen in 1995-1996. Children were mainly from low and middle economic strata and aged between 6 to 12 years. The following data were collected: age, gender, diagnosis, school grade, food intake, maternal complications during pregnancy, perinatal and postnatal neurological risk factors, and neurological signs and handedness. RESULTS: Subjects with RD had a mean age of 102.9 months, were predominantly male (male female ratio, 2:1). Among the study group, 49.1 of the children were diagnosed with RD of a visuo-sensory-motor type, and 75.1 were from early school years (1st to 3rd grades); 27.6 showed evidence of malnutrition. A previous history of language disorders (49.2), and a high frequency of perinatal risk factors and neurological soft signs were also found. CONCLUSIONS: This study shows that variables such as gender, food intake, and genetic and neurological risk factors, were associated with reading disabilities in school children.

EEG alpha desynchronization from rest to silent reading in school children

Objetivo: estudiar la asimetría cerebral en el electroencefalograma (EEG) durante la realización de una tarea de lectura silente. Métodos: se estudió un grupo de escolares durante una tarea de lectura silente buscando lateralización cerebral para el procesamiento verbal, hipotetizando que hay una desincronización asimétrica en la banda alfa provocada por la actividad cognoscitiva. Se estudiaron 25 escolares masculinos de 9-10 años con nivel de lectura adecuado a su edad, provenientes de escuelas públicas y privadas de la Ciudad de México. Se les realizó un estudio de EEG de 16 canales, los registros fueron realizados en reposo con los ojos cerrados y posteriormente durante la lectura en silencio de un texto con material acorde a su edad. El EEG fue analizado por medio de la transformada rápida de Fourier. Se calculó la potencia relativa por espectro de frecuencia dividido en las bandas: delta, theta, alfa, beta-1, beta-2, beta-3. Se compararon los datos de reposo y lectura en las bandas alfa y beta. Resultados: se observaron diferencias significativas en la distribución regional de la potencia relativa durante la lectura asociadas a un reducción generalizada de la actividad alfa, principalmente en el hemisferio izquierdo, así como un incremento frontal de los ritmos beta-2 y beta-3 durante la lectura. Conclusiones: la lectura silente puede producir una desincronización lateralizada del EEG con una reducción de la actividad alfa de predominio en el hemisferio izquierdo; así como, un aumento de los ritmos beta frontales, estas zonas son de conocida participación en el procesamiento del lenguaje.