Cognitive and Functional Consequence of Cardiac Arrest.

Cardiac arrest is associated with high morbidity and mortality. Better-quality bystander cardiopulmonary resuscitation training, cardiocerebral resuscitation principles, and intensive post-resuscitation hospital care have improved survival. However, cognitive and functional impairment after cardiac arrest remain areas of concern. Research focus has shifted beyond prognostication in the immediate post-arrest period to identification of mechanisms for long-term brain injury and implementation of promising protocols to reduce neuronal injury. These include therapeutic temperature management (TTM), as well as pharmacologic and psychological interventions which also improve overall neurological function. Comprehensive assessment of cognitive function post-arrest is hampered by heterogeneous measures among studies. However, the domains of attention, long-term memory, spatial memory, and executive function appear to be affected. As more patients survive cardiac arrest for longer periods of time, there needs to be a greater focus on interventions that can enhance cognitive and psychosocial function post-arrest.

Different timescales for the neural coding of consonant and vowel sounds.

Psychophysical, clinical, and imaging evidence suggests that consonant and vowel sounds have distinct neural representations. This study tests the hypothesis that consonant and vowel sounds are represented on different timescales within the same population of neurons by comparing behavioral discrimination with neural discrimination based on activity recorded in rat inferior colliculus and primary auditory cortex. Performance on 9 vowel discrimination tasks was highly correlated with neural discrimination based on spike count and was not correlated when spike timing was preserved. In contrast, performance on 11 consonant discrimination tasks was highly correlated with neural discrimination when spike timing was preserved and not when spike timing was eliminated. These results suggest that in the early stages of auditory processing, spike count encodes vowel sounds and spike timing encodes consonant sounds. These distinct coding strategies likely contribute to the robust nature of speech sound representations and may help explain some aspects of developmental and acquired speech processing disorders.

Cortical activity patterns predict speech discrimination ability.

Neural activity in the cerebral cortex can explain many aspects of sensory perception. Extensive psychophysical and neurophysiological studies of visual motion and vibrotactile processing show that the firing rate of cortical neurons averaged across 50-500 ms is well correlated with discrimination ability. In this study, we tested the hypothesis that primary auditory cortex (A1) neurons use temporal precision on the order of 1-10 ms to represent speech sounds shifted into the rat hearing range. Neural discrimination was highly correlated with behavioral performance on 11 consonant-discrimination tasks when spike timing was preserved and was not correlated when spike timing was eliminated. This result suggests that spike timing contributes to the auditory cortex representation of consonant sounds.

Elevated blood pressure after craniotomy: A prospective observational study.

PURPOSE: Close hemodynamic monitoring after craniotomy is routine given risk for post-operative hypertension, systemic and neurological complications. Patient and peri-operative variables associated with increased risk of post-craniotomy hypertension and complications are not well understood. Our analysis aims to estimate the incidence and prevalence of post-craniotomy hypertension, its time course, contributing factors, and post-craniotomy complications. MATERIAL AND METHODS: This is a prospective study of patients admitted to the Neurosurgical Intensive Care Unit after an elective craniotomy. Variables associated with pre-surgical risk, demographics, and post-operative care were analyzed. RESULTS: A total of 282 patients were included in the final analysis, 44% had pre-existing hypertension. Post-craniotomy hypertension was seen in 21%, with a higher incidence in patients with pre-existing hypertension (p < .001), smaller craniotomies (p = .0035), and increased use of analgesic medications (p < .001). History of hypertension was the only independent risk factor for post-craniotomy hypertension in a multivariate regression model. Patients who developed post-craniotomy hypertension, showed a significant increase in length of stay, number and duration of antihypertensive treatment. However, post-craniotomy hypertension was not associated with a higher incidence of other post-operative complications. CONCLUSIONS: Development of hypertension after craniotomy is multi-factorial. In this prospective study, a prior history of hypertension was the only associated independent risk factor.

Speech training alters tone frequency tuning in rat primary auditory cortex.

Previous studies in both humans and animals have documented improved performance following discrimination training. This enhanced performance is often associated with cortical response changes. In this study, we tested the hypothesis that long-term speech training on multiple tasks can improve primary auditory cortex (A1) responses compared to rats trained on a single speech discrimination task or experimentally naïve rats. Specifically, we compared the percent of A1 responding to trained sounds, the responses to both trained and untrained sounds, receptive field properties of A1 neurons, and the neural discrimination of pairs of speech sounds in speech trained and naïve rats. Speech training led to accurate discrimination of consonant and vowel sounds, but did not enhance A1 response strength or the neural discrimination of these sounds. Speech training altered tone responses in rats trained on six speech discrimination tasks but not in rats trained on a single speech discrimination task. Extensive speech training resulted in broader frequency tuning, shorter onset latencies, a decreased driven response to tones, and caused a shift in the frequency map to favor tones in the range where speech sounds are the loudest. Both the number of trained tasks and the number of days of training strongly predict the percent of A1 responding to a low frequency tone. Rats trained on a single speech discrimination task performed less accurately than rats trained on multiple tasks and did not exhibit A1 response changes. Our results indicate that extensive speech training can reorganize the A1 frequency map, which may have downstream consequences on speech sound processing.

Similarity of cortical activity patterns predicts generalization behavior.

Humans and animals readily generalize previously learned knowledge to new situations. Determining similarity is critical for assigning category membership to a novel stimulus. We tested the hypothesis that category membership is initially encoded by the similarity of the activity pattern evoked by a novel stimulus to the patterns from known categories. We provide behavioral and neurophysiological evidence that activity patterns in primary auditory cortex contain sufficient information to explain behavioral categorization of novel speech sounds by rats. Our results suggest that category membership might be encoded by the similarity of the activity pattern evoked by a novel speech sound to the patterns evoked by known sounds. Categorization based on featureless pattern matching may represent a general neural mechanism for ensuring accurate generalization across sensory and cognitive systems.

[Metabolic syndrome prevalence and clinical features in blood donors]. / Prevalencia de síndrome metabólico y características clínicas en donadores de sangre.

BACKGROUND: Metabolic syndrome (MS) including obesity, diabetes mellitus, hypertension, dyslipidemia, etc.. is a major cause of morbidity and mortality worldwide. It was reported that 15.9% of blood donors showed changes in fasting plasma glucose. OBJECTIVE: To determine the prevalence of MS in a population of healthy donors in a secondary hospital. MATERIAL AND METHODS: A cross-sectional study, included 726 healthy donors who attended the blood bank HGZ36. The SM was identified with at least 3 of 5 criteria of the NCEP ATPIII, we applied a structured questionnaire. We determined HDL cholesterol, triglycerides, glucose Abnormal Fasting (GAA), hypertension (SAH), body mass index (BMI), waist circumference (WC), hip circumference (NCC). Plan Analysis: prevalence, t student, Chi2. RESULTS: Of the 726 donors, 85.1% were male, according to the ATPIII criteria, 54.8% (398) had a GAA, 63.2% (458) had hypertriglyceridemia, almost 17% (121) presented HDL hypocholesterolemia, 44.1% (320) were overweight by BMI, the prevalence of metabolic syndrome was 54.4%, in comparison by gender, men had a statistically significant difference compared to women, showing an OR = 2.27 (p = 0.0001, 95% CI 1.44-3.60). CONCLUSIONS: MS is highly prevalent in this population, which involves implementing preventive measures, changes in lifestyles and identify risk factors to be free from diseases like diabetes, hypertension, obesity and MS itself.