We are using the maize leaf as an experimental system to ask how positional information establishes the proximal/distal axis. A mature maize leaf has three regions, the distal blade that functions in photosynthesis, the proximal sheath that wraps the stalk, and the ligule, marking a sharp boundary between blade and sheath. The recessive liguleless mutants remove the ligule, but the distinction ...

Directionally selective (DS) neurons are found in the retina and lateral geniculate nucleus (LGN) of rabbits and rodents, and in rabbits, LGN DS cells project to primary visual cortex. Here, we compare visual response properties of LGN DS neurons with those of layer 4 simple cells, most of which show strong direction/orientation selectivity. These populations differed dramatically, suggesting t...

Vision in infant primates is poor, but it is not known which structures in the eye or brain set the main limits to its development. We studied the visual response properties of 348 neurons recorded in the lateral geniculate nucleus (LGN) of macaque monkeys aged 1 week to adult. We measured spatial and temporal frequency tuning curves and contrast responses with drifting achromatic sinusoidal gr...

Let f : [1..n] → [1..n] be a function, and ` : [1..n] → [1..σ] indicate a label assigned to each element of the domain. We design several compact data structures that answer various queries on the labels of paths in f . For example, we can find the minimum label in f(i) for a given i and any k ≥ 0 in a given range [k1..k2], using n lgn+O(n) bits, or the minimum label in f−k(i) for given i and k...

Pairs of units were recorded by single electrodes from cat’s LGN. Three types of pairs were distinguished. Two of them were classified as retinogeniculate pairs with positive cross-correlograms (ON center – ON center, and OFF center – OFF center); the third type consisted of negatively correlated pairs of LGN neurones. In each case the spatiotemporal organizations of both receptive fields (RFs)...

According to a widely held view, neurons in lateral geniculate nucleus (LGN) operate on visual stimuli in a linear fashion. There is ample evidence, however, that LGN responses are not entirely linear. To account for nonlinearities we propose a model that synthesizes more than 30 years of research in the field. Model neurons have a linear receptive field, and a nonlinear, divisive suppressive f...

Coordinated cell polarization and mitotic spindle orientation are thought to be important for epithelial morphogenesis. Whether spindle orientation is indeed linked to epithelial morphogenesis and how it is controlled at the molecular level is still unknown. Here, we show that the NuMA- and Galpha-binding protein LGN is required for directing spindle orientation during cystogenesis of MDCK cell...

Coupling of spindle orientation to cellular polarity is a prerequisite for epithelial asymmetric cell divisions. The current view posits that the adaptor Inscuteable (Insc) bridges between Par3 and the spindle tethering machinery assembled on NuMALGNGαi(GDP), thus triggering apico-basal spindle orientation. The crystal structure of the Drosophila ortholog of LGN (known as Pins) in complex with ...

The feedback connections from the cortical middle temporal (MT) motion area, to layer 6 of the primary visual cortex (V1), have the capacity to drive a cascaded feedback influence from the layer 6 cortico-geniculate cells back to the lateral geniculate nucleus (LGN) relay cells. This introduces the possibility of a re-entrant motion signal affecting the relay of the retinal input through the LG...