Sequential neuronal processing of number values, abstract decision, and action in the primate prefrontal cortex.

Decision-making requires processing of sensory information, comparing the gathered evidence to make a judgment, and performing the action to communicate it. How neuronal representations transform during this cascade of representations remains a matter of debate. Here, we studied the succession of neuronal representations in the primate prefrontal cortex (PFC). We trained monkeys to judge whether a pair of sequentially presented displays had the same number of items. We used a combination of single neuron and population-level analyses and discovered a sequential transformation of represented information with trial progression. While numerical values were initially represented with high precision and in conjunction with detailed information such as order, the decision was encoded in a low-dimensional subspace of neural activity. This decision encoding was invariant to both retrospective numerical values and prospective motor plans, representing only the binary judgment of "same number" versus "different number," thus facilitating the generalization of decisions to novel number pairs. We conclude that this transformation of neuronal codes within the prefrontal cortex supports cognitive flexibility and generalizability of decisions to new conditions.

Renal oxygen content is increased in healthy subjects after angiotensin-converting enzyme inhibition

OBJECTIVE: The association between renal hypoxia and the development of renal injury is well established. However, no adequate method currently exists to non-invasively measure functional changes in renal oxygenation in normal and injured patients. METHOD: R2* quantification was performed using renal blood oxygen level-dependent properties. Five healthy normotensive women (50±5.3 years) underwent magnetic resonance imaging in a 1.5T Signa Excite HDx scanner (GE Healthcare, Waukesha, WI). A multiple fast gradient-echo sequence was used to acquire R2*/T2* images (sixteen echoes from 2.1 ms/slice to 49.6 ms/slice in a single breath hold per location). The images were post-processed to generate R2* maps for quantification. Data were recorded before and at 30 minutes after the oral administration of an angiotensin II-converting enzyme inhibitor (captopril, 25 mg). The results were compared using an ANOVA for repeated measurements (mean + standard deviation) followed by the Tukey test. ClinicalTrials.gov: NCT01545479. RESULTS: A significant difference (p<0.001) in renal oxygenation (R2*) was observed in the cortex and medulla before and after captopril administration: right kidney, cortex = 11.08 ± 0.56ms, medulla = 17.21 ± 1.47ms and cortex = 10.30 ± 0.44ms, medulla = 16.06 ± 1.74ms, respectively; and left kidney, cortex= 11.79 ± 1.85ms, medulla = 17.03 ± 0.88ms and cortex = 10.89 ± 0.91ms, medulla = 16.43 ± 1.49ms, respectively. CONCLUSIONS: This result suggests that the technique efficiently measured alterations in renal blood oxygenation after angiotensin II-converting enzyme inhibition and that it may provide a new strategy for identifying the early stages of renal disease and perhaps new therapeutic targets.

Paralisia hipocalêmica secundária à síndrome de Sjögren / Hypokalemic paralysis secondary to Sjögren's syndrome

A acidose tubula renal (ATR) é uma manifestação extraglandular da síndrome de SJörgen que ocorre em aproximadamente 30 por cento dos pacientes. A ATR é geralmente assintomática, mas pode levar à acidose metabólica e perda renal de potássio, resultando em marcadas alterações clínicas. Descreve-se o caso de uma paciente com 33 anos e SS que desenvolveu paralisia hipocalêmica relacionada à ATR. Discute-se a apresentação clínica e a fisiopatologia do comprometimento renal na SS. Destaca-se a importância da investigação dos eletrólitos e do exame comum de urina em todos os indivídruos com SS, principalmente quando houver cálculo renal

Retinopatia hipertensiva na infância / Hypertensive retinopathy in children

O objetivo do presente trabalho foi o de verificar a incidência e quais os tipos de repercussöes fundoscópicas em criançäs com diagnóstico clínico de hipertensäo arterial sistêmica (HAS). Dezenove crianças foram examinadas e fotodocumentadas. Destas 11 com hipertensäo do tipo secundária. Do total, 7 (37 por cento) exibiram alguma modificaçäo atribuível a doença básica, sendo encontrados na seguinte frequência: estreitamentos arteriolares (16 por cento), aumento da tortuosidade (10,5 por cento) e entrecruzamentos patológicos (10,5 por cento). Nenhuma criança com déficit visual secundário a HAS. Os resultados säo significativos tanto por indicar uma incidência expressiva de alteraçöes retinianas como também por chamar a atençäo de que estes sinais devem ser motivos de investigaçäo clínica quando casualmente detectados durante exames de rotina