orientationselective

Orientation selectivity refers to the property of many neurons in the mammalian visual system, especially in the primary visual cortex (V1), to respond most strongly to edges or bars at a specific orientation. Such neurons exhibit orientation tuning: their firing rate varies with stimulus orientation, peaking at a preferred angle and declining for others. The sharpness of this tuning is described by the orientation bandwidth.

In the cortex, many V1 neurons are orientation-selective, whereas neurons in earlier stages like the LGN generally show little or no orientation bias. The orientation of maximal response is often organized into maps or columns across the cortex, though the exact pattern varies by species.

Orientation selectivity arises from the combination of receptive-field structure and synaptic inputs. Elongated receptive fields in simple cells, together with selective convergence from the LGN and intracortical inhibition and excitation, create a preference for a particular orientation. The development of orientation tuning is experience-dependent and can be altered by patterned visual deprivation during critical periods.

Measuring orientation selectivity typically involves presenting gratings at different orientations while recording neural responses, producing a tuning curve from which the preferred orientation and bandwidth are derived. Orientation selectivity is foundational for edge detection and shape analysis and underpins more complex visual processing.

See also: receptive field, simple cell, complex cell, Hubel and Wiesel, visual cortex, orientation maps.