Impairments in part-whole representations of objects in two cases of integrative visual agnosia.

How complex multipart visual objects are represented perceptually remains a subject of ongoing investigation. One source of evidence that has been used to shed light on this issue comes from the study of individuals who fail to integrate disparate parts of visual objects. This study reports a series of experiments that examine the ability of two such patients with this form of agnosia (integrative agnosia; IA), S.M. and C.R., to discriminate and categorize exemplars of a rich set of novel objects, "Fribbles", whose visual similarity (number of shared parts) and category membership (shared overall shape) can be manipulated. Both patients performed increasingly poorly as the number of parts required for differentiating one Fribble from another increased. Both patients were also impaired at determining when two Fribbles belonged in the same category, a process that relies on abstracting spatial relations between parts. C.R., the less impaired of the two, but not S.M., eventually learned to categorize the Fribbles but required substantially more training than normal perceivers. S.M.'s failure is not attributable to a problem in learning to use a label for identification nor is it obviously attributable to a visual memory deficit. Rather, the findings indicate that, although the patients may be able to represent a small number of parts independently, in order to represent multipart images, the parts need to be integrated or chunked into a coherent whole. It is this integrative process that is impaired in IA and appears to play a critical role in the normal object recognition of complex images.

Human immunodeficiency virus (HIV)-specific antibody in cervicovaginal lavage specimens obtained from women infected with HIV type 1.

To evaluate correlates of anti-human immunodeficiency virus (HIV) type 1 (HIV-1) immunoglobulin (Ig) in the genital tract, anti-HIV-gp120 IgA and IgG titers in cervicovaginal lavage specimens obtained from 104 HIV-1-infected women were measured by enzyme-linked immunosorbent assay. Overall, 24% and 94% of women had detectable anti-gp120 IgA and IgG, respectively. CD4 cell count correlated negatively with total IgA concentration (r=-0.301; P=.0027) and positively with specific IgA activity (anti-gp120 IgA titer/total IgA concentration, r=0.306; P=.0023). Women with bacterial vaginosis had 5-fold lower anti-gp120 IgG titer (P=.0042), 5-fold lower total IgG concentration (P< or =.0001), and 4-fold higher specific IgG activity (P=.0474) compared with women who did not have bacterial vaginosis. Enhanced understanding of correlates of mucosal immunity to HIV-1 may assist in the design of vaccine strategies or in the prevention of vertical transmission of HIV-1.