Visuospatial functions in the rat following injuries to striate, peristriate, and parietal neocortical sites

Abstract

The influenee oflesions located generaIly within four regions of the rat's posterior neocortex upon the aequisition and retention of two-choiee visual discriminations was assessed using a Thompson-Bryant apparatus. The ability to distinguish visual patterns was tested by utilizing stimuli eomposed of 45° versus 135 0 alternating blaek and white stripes (both total and local luminanee eues were eontroIled). "Brightness" discrimination was assessed by using blaek and white eard discriminanda. Posterior parietal injuries resulted in a dysfunction on eaeh of the four tasks, but rats with this injury eventuaIly attained eriterion for eaeh ofthe habits. SmaIler, more anteromedial parietallesions failed to disturb pattern discrimination and were not studied in the other paradigms. The only defieit observed in rats with medial peristriate injuries was a slight retardation in aequisition of the pattern discrimination. Sinee the effects of lateral peristriate and striate injuries upon pattern vision have been weIl described previously, the effects of these lesions on the retention and aequisition of the blaek-white discrimination were studied. Lateral peristriate lesions, but not striate lesions, were associated with a retention loBS of the brightness problem. This loss was detected even with a recovery interval of 60 days. Both striate and lateral peristriate lesions retarded blaek-white discrimination aequisition. Discussion foeuses on the probable natures of the visual dysfunctions associated with these injuries.Ablation of the rat's posterior neocortex has been reported to produce an abolition of form vision (e.g.,

Visually guided locomotion, distractibility, and the missing-stimulus effect in hooded rats with unilateral or bilateral lesions of parietal cortex.

“…Our data add further weight to the argument that Krieg's (1946) area 7 in rat represents a true homologue of PPC in the monkey, sharing many common features (Kolb & Walkey, 1987; McDaniel & Wall, 1988). It would be interesting to know whether other primate deficits such as judgment of relative spatial position (Newcombe, Ratcliff, & Damasio, 1987; Pohl, 1973) are deficient in parietal rats and whether subdivisions exist within parietal cortex, as is the case in the monkey (Hyvarinen & Shelepin, 1979).…”

“…Surface diagrams of lesions are shown in Figures 1 (unilaterals) and 2 (bilaterals), and a coronal reconstruction of a typical unilateral lesion is shown in Figure 3. The region of cortex removed in all cases included Krieg's area 7 (Krieg, 1946) and the cortical regions identified as parietal by previous investigators who used anatomical and behavioral methods (Kolb & Walkey, 1987; McDaniel & Wall, 1988). Although the results of these previous studies showed some variability, the area that all investigators agree represents the parietal field lies on (and extends posteriorly to) the rostrocaudal midpoint of the hemisphere (see Figure 3).…”

“…More restricted damage to the parietal area, particularly in Krieg's areas 7 and the more lateral area 39 (Krieg, 1946), does not produce major visual discrimination impairments but does produce a variety of spatial deficits, for example, on spatial alternation and in spatial mazes (Boyd & Thomas, 1977;Kolb, Sutherland, & Whishaw, 1983;McDaniel, Davall, & Walker, 1989), in navigation toward a hidden platform in a swimming pool task (DiMattia & Kesner, 1988;Kolb & Walkey, 1987), and on the radial arm maze (Kolb et al, 1983). Thus, impairments in locomotor guidance and spatial function seen in earlier studies after very extensive bilateral posterior cortical lesions (e.g., Goodale et al, 1978) might have been due not to striate removal but to rostral encroachment on the parietal area (see McDaniel & Wall, 1988). One component of such deficits might therefore be a rodent equivalent of the visuospatial deficit seen in man and monkey after parietal damage.…”

Object exploration and reactions to spatial and nonspatial changes in hooded rats following damage to parietal cortex or hippocampal formation.

“…The anatomical proximity of the visual and the posterior parietal cortices, which underlies functional relationships, supports the view that visuospatial processing is important (e.g., McNaughton, Leonard, & Chen, 1989; Miller & Vogt, 1984). Moreover, McDaniel and Wall (1988) showed that damage to the rat's posterior parietal cortex results in severe deficits in visuospatial discrimination tasks. However, the lack of deficit concerning the reaction to the novel object in the group PPC rats of the present study suggests that simple visual tasks, with no spatial component, are not sufficient to induce deficits in PPC rats.…”

Effects of lesions of the associative parietal cortex on the acquisition and use of spatial memory in egocentric and allocentric navigation tasks in the rat.

“…One straightforward explanation is that the rats were impaired in perceiving or in organizing the perception of the spatial relationships between landmarks or objects (Kolb, 1990). Although experimental evidence in favor of this hypothesis is limited, its plausibility is supported by the importance of cortico-cortical connections between the APC and the visual areas (Miller & Vogt, 1984;Torrealba, Olavarria, & Carrasco, 1984;Kolb & Walkey, 1987) and by the results of behavioral studies (McDaniel, & Wall, 1987;McNaughton, Leonard, & Chen, 1989). However, the present results suggest that the overall function of the APC cannot be understood without taking into account a "kinesthetic component."…”