Direction-sensitive X and Y cells within the A laminae of the cat's LGNd

Abstract

Drifting sinusoidal gratings, moving bars, and moving spots were employed to study the direction sensitivity of 425 neurons in the A laminae of the cat's LGNd. Thirty-two percent of X-and Y-type LGNd relay cells exhibit significant direction sensitivity when tested with drifting sinusoidal gratings. X and Y cells exhibit the same degree of direction sensitivity. Moving spots and bars elicit direction specific responses fromLGNd cells that are consistent with those elicited when drifting sinusoidal gratings are employed. For cells that are both orientation and direction sensitive, the preferred direction tends to be orthogonal to the preferred orientation. In general, direction sensitivity is strongest at relatively low spatial frequencies, well below the spatial-frequency cutoff for the cell. The presence of significant numbers of direction-sensitiveLGNd cells raises the possibility that subcortical direction specificity is important for the generation of this property in the visual cortex.

Stimulus dependence of orientation and direction sensitivity of cat LGNd relay cells without cortical inputs: A comparison with area 17 cells

“…The materials, methods, visual stimulation, data collection, and statistical analyses used in this study were the same as is described in the companion paper (Thompson et al, 1994). Recordings from LGNd relay cells located in the A and Al layers were made in normal adult cats in which areas 17, 18, 19, and LS were ablated.…”

“…Using the conservative criterion that a bias of 0.1 or greater is significant (see Methods in Thompson et al, 1994), 68% of the relay cells tested in the decorticate cat LGNd were orientation sensitive and 35% were direction sensitive. Using the conservative criterion that a bias of 0.1 or greater is significant (see Methods in Thompson et al, 1994), 68% of the relay cells tested in the decorticate cat LGNd were orientation sensitive and 35% were direction sensitive.…”

“…A cell was considered to be significantly orientation or direction biased if the bias was greater than or equal to 0.1 (see Methods in Thompson et al, 1994). A cell was considered to be significantly orientation or direction biased if the bias was greater than or equal to 0.1 (see Methods in Thompson et al, 1994).…”

“…Hammond and Pomfrett (1990) described four different types of spatial-frequencydependent orientation and direction tuning in cat area 17 (types A-D). 5 in Thompson et al, 1994). 7 illustrates a cell that was direction selective at high spatial frequencies and its direction bias did not vary with spatial frequency (type A - Hammond & Pomfrett, 1990).…”

Abnormal retinotopic organization of the dorsal lateral geniculate nucleus of the tyrosinase-negative albino cat

“…Cats were prepared for electrophysiologic recording as described previously Thompson et al, 1994). Animals were initially anesthetized with ketamine (10 mg/kg), and anesthesia was continued during surgery with halothane (1-2% in a 75-25% N 2 O-O 2 mixture).…”