RhoA co-ordinates with heterotrimeric G proteins to regulate efficacy.
ABSTRACT Heterotrimeric G proteins have a critical role in mediating signal transduction by ligand-stimulated GPCRs. While activation of heterotrimeric G proteins is known to proceed via the G protein guanine nucleotide cycle, there is much uncertainty regarding the process that determines efficacy, the extent of response across signaling pathways. Gα(GTP) can interact with multiple binding partners, including several effectors and regulators. Cross-talk by other receptor-signaling pathways can alter the response. It remains unclear whether G protein efficacy is regulated. This lack of clarity impairs our ability to predict and manipulate the pharmacological behavior of activated G proteins. This review will discuss emerging evidence that implicates monomeric RhoA in the process that regulates G(q) efficacy.
- SourceAvailable from: Marlene Behrmann[show abstract] [hide abstract]
ABSTRACT: Here we investigated the impact of visual discrimination training on neuronal responses to parts of images and to whole images in inferotemporal (IT) cortex. Monkeys were trained to discriminate among 'baton' stimuli consisting of discrete top and bottom parts joined by a vertical stem. With separate features at each end, we were able to manipulate the two parts of each baton independently. After training the monkeys, we used single-cell recording to compare neuronal responses to learned and unlearned batons. Responses to learned batons, though not enhanced in strength, were enhanced in selectivity for both individual parts and for whole batons. Whole-baton selectivity arose from a form of conjunctive encoding whereby two parts together exerted a greater influence on neuronal activity than predicted by the additive influence of each part considered individually. These results indicate a possible neural mechanism for holistic or configural effects in expert versus novice observers.Nature Neuroscience 12/2002; 5(11):1210-6. · 15.25 Impact Factor
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ABSTRACT: With training, an observer's ability to discriminate similar directions of motion gradually improves. A series of studies reveals that this improvement, (1) is restricted to the trained direction and other, similar directions, (2) persists for at least several months, (4) shows appreciable, but not complete, transfer between the two eyes, and (5) is largely restricted to the stimulated region of the field. Moreover, the improvement in direction discrimination does not produce a concomitant change in detection thresholds. In all likelihood, most of the improvement in direction discrimination represents a change in visual function, rather than changes in nonsensory processes.Vision Research 02/1987; 27(6):953-65. · 2.14 Impact Factor
Article: What makes faces special?[show abstract] [hide abstract]
ABSTRACT: What may be special about faces, compared to non-face objects, is that their neural representation may be fundamentally spatial, e.g., Gabor-like. Subjects matched a sequence of two filtered images, each containing every other combination of spatial frequency and orientation, of faces or non-face 3D blobs, judging whether the person or blob was the same or different. On a match trial, the images were either identical or complementary (containing the remaining spatial frequency and orientation content). Relative to an identical pair of images, a complementary pair of faces, but not blobs, reduced matching accuracy and released fMRI adaptation in the fusiform face area.Vision Research 11/2006; 46(22):3802-11. · 2.14 Impact Factor