A forebrain lesion preventing imprinting in domestic chicks

Abstract

Newly hatched domestic chicks were subjected to bilateral aspiration lesions of the anterior, dorsal, posterior or lateral regions of the forebrain and then were reared separately with one of two types of imprinting object. Between 3 and 10 days later they were tested for imprinting, pecking accuracy, visual looming and auditory startle responses. Lateral and dorsal lesion groups differed from a control group in the number of successful discriminations of their imprinting object and the lateral group was not significantly different from a random expectancy. All groups were impaired in pecking accuracy but the lateral group was the most severely affected. Looming responses and post startle freezing behaviour were reduced only in the posterior and dorsal groups which were also the least responsive in the imprinting tests. It was concluded that the lateral forebrain area is critically and specifically involved in the visual learning of imprinting being necessary for the discrimination of, but not for approach responsiveness to, imprinting objects.

Roots of a social brain: Developmental models of emerging animacy-detection mechanisms

“…Interestingly, in chicks imprinted to a non-preferred colour, post-imprinting telencephalic ablation erased the imprinted memory, but did not restore the initial genetically determined colour preference . This data suggested that imprinting modifies the initially subtelencephalic representation of genetically coded colour preferences, a possibility that was considered also earlier by Salzen et al (1975). This observation is of particular interest because it indicates that neuronal plasticity is also existent and can be measured in areas involved in predispositions.…”

Acoustic imprinting leads to differential 2-deoxy-D-glucose uptake in the chick forebrain.

“…In chicks, lesions in that area drastically decreased visual imprintability and retention, as reported by Salzen et a. (5)(6)(7). But whether acoustic imprinting was similarly affected was not tested.…”

A psychobiological theory of attachment

“…Habit (procedural memory) and memory (episodic) appear to involve separate neural systems in mammals. It is interesting that there are two conflicting claims for the brain region critical for imprinting in chicks, one in the lateral neostriatum (Salzen et al 1975; and another in the medial hyperstriatum (Horn 1985). The two research groups use different imprinting paradigms: Salzen's group uses mother surrogates with which the chicks interact; the Horn group restricts its chicks to approach behaviour at a distance.…”