Effects of early experience upon orientation sensitivity and binocularity of neurons in visual cortex of cats.

Abstract

The class of neurons within the visual cortex of normal adult cats that has the smallest receptive fields (<2.25 degrees2) and that responds only to low rates of stimulus motion (S5O0/sec) responds preferentially to lines oriented about either the horizontal axis (+22.50) or the vertical axis (±22.50). In animals reared without exposure to patterned visual stimulation, many of these cells display orientation preferences but are activated monocularly. In contrast, in normal animals, neurons that have larger receptive fields or that respond to higher rates of stimulus motion do not exhibit a similar bias in the distribution of their orientation preferences. Cells of this type, studied in animals reared without exposure to patterned visual stimuli, are activated binocularly but do not display orientation preferences.Three classes of cells have been identified in the retina and in the dorsal lateral geniculate nucleus (LGNd) of the cat: X cells, Y cells, and W cells. During postnatal development these three neuron types are not affected equally by visual stimulation-the populations of X cells and W cells in the cat's visual system appear to be less dependent than the population of Y cells upon sensory stimulation for the maintenance or for the development of normal function (1-5). The manner in which these differences in experience sensitivity in the retina and LGNd affect cortical development, however, remains unclear (6).To examine further the role that early visual experience plays in the development or maintenance of the response properties of cortical neurons, we have compared cells in the visual cortex of normal cats with those in cats reared from birth for prolonged periods without exposure to patterned visual stimuli. We now report that the class of cortical cells found in normal cats that has the smallest receptive fields and that responds only to relatively low rates of stimulus motion responds preferentially to horizontal and to vertical lines. These cells appear to be insensitive to early experience for the development or maintenance of orientation sensitivity but appear to be sensitive to such experience for the development or maintenance of binocularity.

Tactile spatial sensitivity and anisotropy

“…In vision, for example, a central mechanism is thought to be responsible for anisotropy (De Valois, Yund, & Hepler, 1982;Leventhal & Hirsch, 1977;Mansfield, 1974;Mansfield & Ronner, 1978;Orban & Kennedy, 1981). In visual anisotropy, greater sensitivity is found for vertical and horizontal orientations than for the oblique orientation.…”

Representation of Cardinal Contour Overlaps Less With Representation of Nearby Angles in Cat Visual Cortex

“…Investigators reported that in both developing and adult ferrets, larger areas were activated by horizontal and vertical contours than by oblique contours (Chapman and Bonhoeffer 1998;Chapman et al 1996;Coppola et al 1998;Rao et al 1997;White et al 2001). In cats and kittens, some electrophysiological (Albus 1975;Bauer and Jordan 1993;De Valois et al 1982;Fregnac and Imbert 1978;Kennedy and Orban 1979;Leventhal and Hirsch 1977;Mansfield and Ronner 1978;Payne and Berman 1983;Pettigrew et al 1968) and optical imaging (Dragoi et al 2001;Muller et al 2000) studies have suggested that more cortical cells tend to display horizontal or vertical preferences, and cortical cells preferring horizontal or vertical orientations are more narrowly tuned (Kennedy and Orban 1979;Rose and Blakemore 1974) in the primary visual cortex. However, investigators have largely ignored the fundamental question of how much the representation of a given angle overlaps with the representation of nearby angles.…”

The visual system of the cat

“…There is some reason to believe that the precise nature of these cortical deficits depends on whether binocular deprivation results from lid suture as opposed to dark-rearing . Of intriguing significance are the findings of Blakemore and Van Sluyters (1975) and of Leventhal and Hirsch (1977): In binocularly deprived cats, those cortical cells which are orientation selective tend to be of the simple type. This raises the possibility that the normal array of X cells in the LON of binocularly deprived cats is projecting to simple cells in layer IV of visual cortex, thereby providing some substrate for orientation selectivity.…”