Individual Differences in the Alignment of Structural and Functional Markers of the V5/MT Complex in Primates.

Extrastriate visual area V5/MT in primates is defined both structurally by myeloarchitecture and functionally by distinct responses to visual motion. Myelination is directly identifiable from postmortem histology but also indirectly by image contrast with structural magnetic resonance imaging (sMRI). First, we compared the identification of V5/MT using both sMRI and histology in Rhesus macaques. A section-by-section comparison of histological slices with in vivo and postmortem sMRI for the same block of cortical tissue showed precise correspondence in localizing heavy myelination for V5/MT and neighboring MST. Thus, sMRI in macaques accurately locates histologically defined myelin within areas known to be motion selective. Second, we investigated the functionally homologous human motion complex (hMT+) using high-resolution in vivo imaging. Humans showed considerable intersubject variability in hMT+ location, when defined with myelin-weighted sMRI signals to reveal structure. When comparing sMRI markers to functional MRI in response to moving stimuli, a region of high myelin signal was generally located within the hMT+ complex. However, there were considerable differences in the alignment of structural and functional markers between individuals. Our results suggest that variation in area identification for hMT+ based on structural and functional markers reflects individual differences in human regional brain architecture.

Influenza A viruses isolated from migrating ducks in Oklahoma.

Nine type A influenza viruses were isolated from migrating and wintering ducks in Oklahoma in 1976-77. Antigenic classification of the viruses isolated revealed three different subtypes: Hav1 Nav2, Hws N1, and Hav6 N2. Transmission of influenza viruses from the wild ducks to sentinel birds (McGraw mallards) on the same lakes was not detected.

Structural changes associated with type-A influenza in Mallard duck tracheal organ culture.

Mallard duck tracheal organ cultures were used to study structural changes associated with infection with type-A influenza (A/Turkey/WIS/68) (H9N2) at the light-microscope and electron-microscope levels. Light-microscope changes in infected organ culture were cytoplasmic vacuolization, nuclear swelling, reduction in ciliated epithelium, and sloughing of epithelial cells. Ultrastructural changes included the loss of cilia and microvilli, distortion and swelling of cellular organelles, breakdown of intercellular junction, and apparent phagocytosis of the ciliated epithelium. Numerous budding virions were noted at the plasmalemma. Virus was detected by egg inoculation from all experimental cultures throughout the 192-hour experiment.