Biomedical subjects
Publications and source records attributed to M Greenlee.
Synthesis of a series of fused pyrazole tetrahydrofluorenone analogs which are potent, ERbeta subtype selective ligands is described. Analogs possessing subnanomolar ERbeta binding, greater than 100-fold ERbeta-selectivity, and oral bioavailability are reported.
BACKGROUND: Traditionally, colour information is assumed to be carried by neural channels in the parvocellular pathway and to be encoded in an opponent manner, while other, non-parvocellular, spectrally non-opponent channels are thought to play no part in colour vision. But is the parvocellular pathway the only way that colours can be discriminated in human vision? We studied two patients with cerebral achromatopsia, who lack conscious colour perception but are nevertheless able to make use of colour information. In particular, we investigated whether, in these patients, colour discrimination is mediated by the parvocellular pathway. RESULTS: The achromatopsic patients carried out a forced-choice colour- and luminance-discrimination task, and showed clear evidence of unconscious colour processing, consistent with previous studies. We added different types of luminance noise to see when this unconscious colour information could be masked. The results of the colour-discrimination-with-noise and the brightness-non-additivity experiments showed a double-dissociation between patients. This indicates that, in one patient, unconscious colour discrimination may be subserved by a spectrally non-opponent mechanism, which does not have the characteristics of the parvocellular pathway and which is responsive to fast flicker. Spectral sensitivity, contrast sensitivity and motion perception experiments confirmed that this patient lacks a working opponent parvocellular system. The second achromatopsic patient showed evidence of a residual parvocellular system. CONCLUSIONS: Our results show that chromatic discrimination need not be mediated by neural mechanisms, the parvocellular system in particular, normally assumed to subserve conscious colour perception. Such discrimination may be mediated by a neural subsystem which responds to fast flicker, is spectrally non-opponent, and supports normal motion perception.
This paper reports the results of a study of the persistence of individual differences in the phonological development of 10 normally developing children observed at age 1 year and again at age 3 years. Data were based on 1/2-hr audio and video recordings of weekly spontaneous mother-child interaction sessions in the home between 9 and 17 months and at 36 months. In addition, phonological and cognitive probes were administered at age 3. At age 1 the children were compared at four times selected on the basis of the number of different word types used in a session. Preferences for particular phonological categories (fricatives, liquids, final consonants) were found not to correspond to relative mastery of those categories at age 3. Based on both babble and words, high use of vocalizations containing true consonants was found to be predictive of greater phonological advance at age 3. Phonological errors of two kinds were distinguished for age 3: those resulting from difficulty with specific segments and those more typical of younger children, involving the rearrangement, assimilation, or deletion of segments or syllables (prosodic errors). The children differed in intelligibility and in specific segment substitutions and cluster reductions. They also differed in the proportion of prosodic errors made and in consistency in segmental errors. Lastly, aspects of cognitive or learning style as expressed in phonological organization were found to be recognizable at both age 1 and age 3.
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In studying language change, Ohala and Lorentz (1977) observed that when the labial-velar glide [w] occurs adjacent to fricative noise, the resulting complex of acoustic features is most often perceived and pronounced as a labial, rather than a velar consonant. However, contemporary Spanish, as spoken in Mexico and the U.S. Southwest, presents a somewhat different pattern. The current research examined two directional predictions based on Ohala and Lorentz (1977) with reference to the perception and production of Spanish fricatives by Chicano children and adults: A Differential Effect of Context hypothesis (more labial/velar fricative interchanges will occur before rounded, rather than unrounded vowels or glides), and a Labial Predominance hypothesis (before a following rounded vowel or glide, labial fricatives will be favored in labial/velar interchanges). Results of perceptual tests provided support for these acoustically-based predictions, but subjects' productions also showed strong influence from sociolinguistic factors in the opposite direction.