Statistical Significance of Precisely Repeated Intracellular Synaptic Patterns

Can neuronal networks produce patterns of activity with millisecond accuracy? It may seem unlikely, considering the probabilistic nature of synaptic transmission. However, some theories of brain function predict that such precision is feasible and can emerge from the non-linearity of the action potential generation in circuits of connected neurons. Several studies have presented evidence for and against this hypothesis. Our earlier work supported the precision hypothesis, based on results demonstrating that precise patterns of synaptic inputs could be found in intracellular recordings from neurons in brain slices and in vivo. To test this hypothesis, we devised a method for finding precise repeats of activity and compared repeats found in the data to those found in surrogate datasets made by shuffling the original data. Because more repeats were found in the original data than in the surrogate data sets, we argued that repeats were not due to chance occurrence. Mokeichev et al. (2007) challenged these conclusions, arguing that the generation of surrogate data was insufficiently rigorous. We have now reanalyzed our previous data with the methods introduced from Mokeichev et al. (2007). Our reanalysis reveals that repeats are statistically significant, thus supporting our earlier conclusions, while also supporting many conclusions that Mokeichev et al. (2007) drew from their recent in vivo recordings. Moreover, we also show that the conditions under which the membrane potential is recorded contributes significantly to the ability to detect repeats and may explain conflicting results. In conclusion, our reevaluation resolves the methodological contradictions between Ikegaya et al. (2004) and Mokeichev et al. (2007), but demonstrates the validity of our previous conclusion that spontaneous network activity is non-randomly organized

Pseudocystic form of neurocryptococcosis in pregnancy: case report Neurocriptococose na gravidez: forma pseudocística. Relato de Caso

We report a case of neurocryptococcosis which is unique in the literature because the patient had a pseudocystic form of the disease during pregnancy and without any evidence of AIDS. The clinical picture was that of intracranial hypertension and the epidemiological background was highly suggestive of cysticercosis. CT showed multiple round hypodense lesions in the basal ganglia and cerebellum, without contrast enhancement. Since a scolex was not visible, the diagnosis of neurocysticercosis was considered probable. CSF examination was not performed in view of its high risk. The patient had progressive downhill course. Autopsy disclosed multiple gelatinous pseudocysts in the cerebral and cerebellar gray matter, containing abundant Cryptococcus neoformans. Meningeal involvement was minimal. The child was delivered by caesarean section and was free of infection, but died later of hyaline membrane disease. The neuroimaging appearances of this rare instance of the pseudocystic form of neurocryptococcosis mimicked closely neurocysticercosis and only postmortem examination allowed correct diagnosis. The pseudocystic form has so far only been reported in AIDS.<br>Relatamos o primeiro caso da forma pseudocística da neurocriptococose na gravidez, em paciente sem evidência de AIDS. O quadro clínico era de hipertensão intracraniana que se manifestou no segundo trimestre da gravidez. A tomografia computadorizada do crânio evidenciava múltiplas lesões hipodensas, císticas, não impregnadas por contraste, localizadas na substância cinzenta cerebral e cerebelar. Dados epidemiológicos, clínicos e tomográficos apontavam para o diagnóstico provável de neurocisticercose. A autópsia, porém, revelou múltiplos pseudocistos de material gelatinoso com Cryptococcus neoformans em abundância. Havia mínimo comprometimento meníngeo. A revisão da literatura mostrou que a forma pseudocística da neurocriptococose só foi até o momento relatada em pacientes com AIDS. Os casos de neurocriptococose na gravidez até hoje publicados foram todos da forma meningítica