Development of Orientation Preference Maps in Ferret Primary Visual Cortex

Abstract

The development of orientation preference maps was studied in ferret primary visual cortex using chronic optical imaging of intrinsic signals. The emergence and maturation of the maps were examined over time in single animals. The earliest age at which cortical domains selectively responsive to particular stimulus orientations were observed varied considerably between individuals, from postnatal day 31 to 36. In all cases, the earliest maps seen were low-contrast, with regions of orientation-specific activity that were difficult to distinguish from noise. These early maps matured over a period of several days into the high-contrast, patchy maps typical of adult animals. The structure of the orientation maps was remarkably constant over time. The indistinct features in the earliest maps were always patches of the same sizes and shapes and at the same locations as in the maps obtained in subsequent recording sessions. Details of the more mature maps, including the relative intensities of individual iso-orientation domains, were also constant from one recording session to another over periods of several weeks. The patterning of iso-orientation domains in ferret primary visual cortex thus is established early in development and remains stable over time, unaffected by either normal visual experience or the anatomical rearrangements of geniculocortical afferents into eye-specific domains.

Analysis of the postnatal growth of visual cortex

“…When this model is applied to the development of visual cortical columns, it predicts that where the shape of V1 is conserved and merely expands, the optimal patterns will be unchanged. This notion is supported by recent findings that the ocular dominance pattern in newborn macaques is already adult-like (Horton & Hocking, 1996a) and that the orientation map in young ferrets is also similar to those found in the adult (Chapman et al, 1996).…”

Grid cells and cortical representation

“…A key question for the future will be to determine which cells wire together in such networks, at which developmental stage this wiring takes place, and how cells of the same network find each other. For functional maps in the visual cortex there is much more information on this question: it is now reasonably well established that activitydependent mechanisms are involved in forming the map or, in the special case of rodents, connecting cells with particular response properties [52][53][54] . The basic organization of connections in the visual pathway is established prior to visual experience as a result of spontaneous correlated activity (retinal and cortical waves) [55][56][57][58] or by means of gap-junction coupling of clonally related neurons at prenatal developmental stages 59,60 .…”

Constructing visual function through prenatal and postnatal learning

“…Recent advances in experimental imaging technologies have made it possible to measure the full map of orientation preferences in young animals. Such experiments show that large-scale orientation maps exist prior to visual experience, and that these maps have many of the same features as found in adults (Chapman, Stryker, and Bonhoeffer 1996;Crair et al 1998;Gödecke, Kim, Bonhoeffer, and Singer 1997). Furthermore, the global patterns of orientation-selective patches in the maps appear to change very little with normal visual experience, even as the individual neurons gradually become more selective for orientation (Chapman and Stryker 1993;Crair et al 1998;Gödecke et al 1997).…”