The effects of Wulst ablations on color, brightness and pattern discrimination in pigeons (Columba livia)

Abstract

Pigeons were trained to peck at a transparent response key on which was projected either a color, brightness or pattern discrimination problem. Each subject was trained on only one of these problems. Training was continued until the subjects had reached asymptote. After reaching asymptote, subjects received brain ablations (by subpial suction) according to the following design: hyperstriate group, tissue removed from the Wulst; ablated controls, tissue removed from the neostriatum and corticoid areas; operated controls, no neural tissue intentionally removed. After a two week recovery period, each subject was re-tested on the same discrimination task that it had learned pre-operatively. Those birds with ablations of the Wulst showed deficits in performance on the brightness and pattern problems, but not on the color problem. Ablated and control subjects showed no post-operative deficits. These findings indicate that the Wulst functions in brightness and pattern discrimination, but may not be essential for color discrimination.

The effects of lesions in telencephalic visual areas on stimulus generalization in pigeons

“…Thus, the discriminative impairment found by Macphail (1971), Pritz, Mead, andNorthcutt (1970), andZeigler (1963) on go/no-go discriminations was not replicated here. As noted above, Macphail (1975) also failed to replicate this effect.…”

“…An additional purpose was to examine the effects of these lesions on a particular discriminative learning task. There have been two reports of deficits on visual discriminative learning after Wulst lesions (Pritz, Mead, & Northcutt, 1970;Zeigler, 1963). These findings have not been confirmed by other authors, however (Hodos, Karten, & Bonbright, 1973;Macphail, 1976b).…”

Visual Wulst Influences on the Optic Tectum of the Pigeon

“…The effects of lesions of the different visual stations on visually guided behavior support, in general, the concept of a dual visual system, in showing that consistent deficits in pattern, brightness, and color discrimi nation follow lesions of the tectofugal system [Hodos and Karten, 1966, 1974Hodos, 1969;Hodos and Fletcher, 1974;Jarvis, 1974]; whereas lesions of the thalamofugal system are still compatible with brightess or simple form discrimination , but affect the performance of more subtle discrimination tasks [Pritz et al, 1970;Hodos and Bonbright, 1974], Although not all of the results of the ablation studies are amenable to an explanation in known electrophysiological terms, an interesting out come of these studies is that the discrimination deficits which follow the combined lesions of nucleus rotundus and nucleus opticus principalis thalami are more severe than those obtained by destruction of the nucleus rotundus alone [Hodos et ai, 1973]. This observation raises the problem of the mutual interplay between the two visual systems.…”

Participation of the homing pigeon thalamofugal visual pathway in sun‐compass associative learning

“…In general, the wulst lesion damage was comparable to that which produces modest deficits in visual discrimination tasks and substantial impairments in some learning tasks (Pritz et al ., 1970; Macphail, 1971, 1976; Hodos et al ., 1973; Delius et al ., 1984; Hodos et al ., 1984; Shimizu & Hodos, 1989). Similarly, the ectostriatum lesion damage was comparable to that which produces substantial impairments in visual discrimination tasks carried out in an operant chamber (Bessette & Hodos, 1989; Hodos & Karten, 1970).…”