Vocal Communications and the Maintenance of Population Specific Songs in a Contact Zone

Bird song has been hypothesized to play a role in several important aspects of the biology of songbirds, including the generation of taxonomic diversity by speciation; however, the role that song plays in speciation within this group may be dependent upon the ability of populations to maintain population specific songs or calls in the face of gene flow and external cultural influences. Here, in an exploratory study, we construct a spatially explicit model of population movement to examine the consequences of secondary contact of populations singing distinct songs. We concentrate on two broad questions: 1) will population specific songs be maintained in a contact zone or will they be replaced by shared song, and 2) what spatial patterns in the distribution of songs may result from contact? We examine the effects of multiple factors including song-based mating preferences and movement probabilities, oblique versus paternal learning of song, and both cultural and genetic mutations. We find a variety of conditions under which population specific songs can be maintained, particularly when females have preferences for their population specific songs, and we document many distinct patterns of song distribution within the contact zone, including clines, banding, and mosaics

Curitiba acute ischemic stroke protocol: a university hospital and EMS initiative in a large Brazilian city

Few healthcare centers in Brazil perform thrombolytic therapy for acute ischemic stroke (AIS) patients. OBJECTIVE: The aim of this study was to describe an interinstitutional protocol for the rapid identification and thrombolytic treatment of AIS patients at a public health hospital in a large Brazilian city. METHOD: Emergency medical services (EMS) personnel evaluated 433 patients with possible stroke during a six-month period. After a standard checklist, patients with suspected AIS and symptoms onset of less than two hours were evaluated at our University Hospital (UH). RESULTS: Sixty-five (15%) patients met the checklist criteria and had a symptom onset of less than two hours, but only 50 (11%) patients were evaluated at the UH. Among them, 35 (70%) patients had ischemic stroke, 10 (20%) had hemorrhagic stroke, and 5 (10%) had other diagnoses. Of the 35 ischemic stroke patients, 15 (43%) underwent IV thrombolysis. CONCLUSION: The present study demonstrated that trained EMS workers could help to improve the rate of thrombolytic treatment in large Brazilian cities. Permanent training programs for EMS and hospital staff, with quality control and correct identification of AIS patients, should be implemented to increase appropriate thrombolytic therapy rates in Brazil

Tuning for spectro-temporal modulations as a mechanism for auditory discrimination of natural sounds

Vocal communicators discriminate conspecific vocalizations from other sounds and recognize the vocalizations of individuals. To identify neural mechanisms for the discrimination of such natural sounds, we compared the linear spectro-temporal tuning properties of auditory midbrain and forebrain neurons in zebra finches with the statistics of natural sounds, including song. Here, we demonstrate that ensembles of auditory neurons are tuned to auditory features that enhance the acoustic differences between classes of natural sounds, and among the songs of individual birds. Tuning specifically avoids the spectro-temporal modulations that are redundant across natural sounds and therefore provide little information; rather, it overlaps with the temporal modulations that differ most across sounds. By comparing the real tuning and a less selective model of spectro-temporal tuning, we found that the real modulation tuning increases the neural discrimination of different sounds. Additionally, auditory neurons discriminate among zebra finch song segments better than among synthetic sound segments