Learning to see the trees before the forest: Reversible deactivation of the superior colliculus during learning of local and global visual features

Abstract

Previous studies have established that deactivation of the superior colliculus severely retards the normally rapid learning of pattern discriminations in the mature cat. The purpose of this study was to test the hypothesis that the midbrain plays an important role in the learning of simple pattern discriminations and that the contribution of this pathway is to the perception of global, rather than local, features of a figure. To answer this question, pattern discrimination learning was studied in three intact cats and in three experimental cats during bilateral reversible deactivation of the superficial layers of the superior colliculus (SC). The animals concurrently learned to discriminate three pairs of compound visual patterns composed of small (local element) Ts or 7s. Congruent and incongruent stimulus pairs were large (global) Ts vs. 7s comprising the same or different local elements, respectively. The random stimulus pair consisted of randomly scattered local elements (Ts vs. 7s). The animals were trained to respond to the large Ts in the congruent and incongruent pairs and the small Ts in the random pair. In the normal cats, learning of the random pair was much slower than the learning of the congruent and incongruent pairs. This finding demonstrated the theory of global precedence, because the animals learned the global features of the congruent and incongruent pairs much more quickly than the local features of the random pair. In contrast, during bilateral deactivation of the superficial layers of the SC, the learning of the incongruent pair was significantly retarded and took longer to learn than the random pair. Congruent and random pair learning rates were unchanged. The specific deficit in learning the incongruent pair indicates that the learning of global, but not local, elements of the visual pattern is impaired during deactivation of the SC. The unimpaired use of local features permitted the animals to learn the congruent and random pairs at normal rates. Therefore, deactivation of the superficial layers of the SC during pattern discrimination learning reverses the precedence for global visual features that is typical of normal learning. concurrent learning ͉ global precedence ͉ feature detection ͉ form discrimination ͉ cat

A Prototypical Template for Rapid Face Detection Is Embedded in the Monkey Superior Colliculus

“…These lateral intrinsic connections within the SC might contribute to the relative selectivity of the SC neurons to the face-like patterns. A previous behavioral study also reported that deactivation of the superficial layer of the cat SC delayed learning of global, but not local, features of composite figures (Lomber, 2002), suggesting an SC involvement in integration of global visual information. Furthermore, the complex interaction between a stimulus and a RF could affect neuronal responses to the visual stimulus in a single neuronal level and might result in different patterns of neuronal responses to visual stimuli at a population level.…”

Long‐lasting Anticonvulsant Effect of Focal Cooling on Experimental Neocortical Seizures

“…In this and a previous article, we observed no signs of damage after cooling cortex (3). Furthermore, Lomber (17–19, and personal communication from Dr. Stephen Lomber) has used much more extreme, reversible cortical cooling to localize function in the mammalian neocortex and has seen no evidence of any cortical injury from daily (≤1.5 hours), cortical cooling to <20°C in cats (2.5 years) and monkeys (1.5 years).…”

The Extrageniculate Visual Pathway Generates Distinct Response Properties in the Higher Visual Areas of Mice

“…However, many studies performed using nonprimate mammal species indicate the importance of the extrageniculate visual pathway for higher visual area functions. Many visual capabilities, including pattern and form discrimination, are preserved after V1 deactivation/destruction in many mammal species, such as rodents [4,5], cats [6], and tree shrews [7], when some higher visual areas remain intact. Activities in higher visual areas are also preserved after V1 deactivation/ destruction [8,9].…”

“…Activities in higher visual areas are also preserved after V1 deactivation/ destruction [8,9]. The extrageniculate visual pathway is considered to be at least partly responsible for these residual capabilities and activities [2,4,6]. SC deactivation/destruction alters the neural properties of some higher visual areas in cats [10], causes visual neglect in many animal species [11], and impairs some visual capabilities in cats, including simple-pattern and form discrimination [6].…”