Inhibition of the LH Surge by Restraint Stress in Cyclic Rats: Studies on the Role of GABAA and GABAB Receptors

There is evidence that stress can alter the activity in the brain of gamma-aminobutyricacid (GABA), a neurotransmitter that has been implicated in the regulation of LH secretion. In the present study the role of GABA in the restraint stress-induced inhibition of the LH surge was investigated in the intact cyclic rat. Intracerebroventricular (icv) administration of the GABAA receptor agonist muscimol (0.1, 0.5 or 1 μg) 5 min before the presumed onset of the pro-oestrous LH surge (at 0900 h) caused a dose dependent suppression of the surge. A single dose of the GABAB receptor agonist baclofen (1 μg; icv) injected at 0855 h postponed the onset of the LH surge, and repeated injections at 0855 and 1130 h suppressed the surge. These data indicate that GABA-ergic activity in the brain can inhibit the LH surge in the cyclic rat via GABAA and GABAB receptors. Pro-oestrous rats were subjected to 5 hrs of restraint starting at 0855 h. Pretreatment with the GABAA receptor antagonist bicuculine (1 μg; icv) at 0840, 0940 and 1040 h or pretreatment with the GABAB receptor antagonist phaclofen (10 μg; icv) at 0840 h were ineffective in preventing the restraint-induced inhibition of the LH surge. The results suggest that GABAA and GABAB receptors are not involved in the inhibitory effect of restraint stress on the LH surge.     

Visual categorization of natural stimuli by domestic dogs

One of the fundamental issues in the study of animal cognition concerns categorization. Although domestic dogs (Canis familiaris) are on the brink to become one of the model animals in animal psychology, their categorization abilities are unknown. This is probably largely due to the absence of an adequate method for testing dogs’ ability to discriminate between large sets of pictures in the absence of human cueing. Here we present a computer-automated touch-screen testing procedure, which enabled us to test visual discrimination in dogs while social cueing was ruled out. Using a simultaneous discrimination procedure, we first trained dogs (N = 4) to differentiate between a set of dog pictures (N = 40) and an equally large set of landscape pictures. All subjects learned to discriminate between the two sets and showed successful transfer to novel pictures. Interestingly, presentation of pictures providing contradictive information (novel dog pictures mounted on familiar landscape pictures) did not disrupt performance, which suggests that the dogs made use of a category-based response rule with classification being coupled to category-relevant features (of the dog) rather than to item-specific features (of the background). We conclude that dogs are able to classify photographs of natural stimuli by means of a perceptual response rule using a newly established touch-screen procedure. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Learning of an oddity rule by pigeons in a four-choice touch-screen procedure

Six pigeons were trained to peck at a target (odd stimulus) that was presented on a touch-screen together with three identical distractors (non-odd stimuli). The target could be either a square or a circle that was either blue or green, and the distractors in each trial were always of the opposite form and color to the target. Thus, the birds could solve the task by attending to color, form, or both. Transfer tests showed that performance was not disrupted by novel forms, stimulus sizes, distractor numbers, and display configurations, but broke down with novel stimulus types (textured stimuli, clip art images, and photographs). Transfer to novel colors was, for the most part, restricted to trials in which only one component—target or distractors, but not both—had a novel color. This suggested that the pigeons used a couple of if–then rules rather than an oddity concept to solve the task, and that color differences between target and distractors were the only cue upon which responding was based. A control experiment with the order of color and form tests being reversed excluded the possibility of the prevalence of color being an artifact of task order and reinforcement contingencies.     

The Multi-Stimulus Box: An innovative learning device for the comparative study of object perception and recognition with various types of stimuli

In this article, we report the construction of a novel type of automated learning device for exploring a broad range of issues in animal visual cognition. The testing box (Multi-Stimulus Box, or MSB) we describe is an experimental chamber that enables the flexible presentation of various stimulus types while providing control over incidental cues to the greatest possible extent. Among the stimuli that can be presented are photographs, real objects, and even holograms. The MSB allows for comparative research across different stimulus qualities and species, and is thus a promising tool for advancing our understanding of the role of stimulus qualities for animals' perception, discrimination, and categorization of objects.     

Inferential reasoning by exclusion in pigeons, dogs, and humans

The ability to reason by exclusion (which is defined as the selection of the correct alternative by logically excluding other potential alternatives; Call in Anim Cogn 9:393–403 2006) is well established in humans. Several studies have found it to be present in some nonhuman species as well, whereas it seems to be somewhat limited or even absent in others. As inconsistent methodology might have contributed to the revealed inter-species differences, we examined reasoning by exclusion in pigeons (n = 6), dogs (n = 6), students (n = 6), and children (n = 8) under almost equal experimental conditions. After being trained in a computer-controlled two-choice procedure to discriminate between four positive (S+) and four negative (S−) photographs, the subjects were tested with displays consisting of one S− and one of four novel stimuli (S′). One pigeon, half of the dogs and almost all humans preferred S′ over S−, thereby choosing either by novelty, or by avoiding S− without acquiring any knowledge about S′, or by inferring positive class membership of S′ by excluding S−. To decide among these strategies the subjects that showed a preference for S′ were then tested with displays consisting of one of the S′ and one of four novel stimuli (S′′). Although the pigeon preferentially chose the S′′ and by novelty, dogs and humans maintained their preference for S′, thereby showing evidence of reasoning by exclusion. Taken together, the results of the present study suggest that none of the pigeons, but half of the dogs and almost all humans inferred positive class membership of S′ by logically excluding S−. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

The Vienna comparative cognition technology (VCCT): An innovative operant conditioning system for various species and experimental procedures

This article describes a laboratory system for running learning experiments in operant chambers with various species. It is based on a modern version of a classical learning chamber for operant conditioning, the so-called ??Skinner box??. Rather than constituting a stand-alone unit, as is usually the case, it is an integrated part of a comprehensive technical solution, thereby eliminating a number of practical problems that are frequently encountered in research on animal learning and behavior. The Vienna comparative cognition technology combines modern computer, stimulus presentation, and reinforcement technology with flexibility and user-friendliness, which allows for efficient, widely automatized across-species experimentation, and thus makes the system appropriate for use in a broad range of learning tasks.     

A new learning paradigm elicits fast visual discrimination in pigeons

The authors describe a novel multistimulus, multiple-matching learning paradigm for pigeons, which they believe not only simulates pigeons' natural foraging behavior but also more realistically shows their visual discrimination ability. A touch screen thin film transistor panel shows a stimulus configuration consisting of a 2-dimensional array of bitmap images that changes from trial to trial. The pigeon's task during each trial is to peck at images that are defined as positive by the experimenter. An experiment exploring the ability of pigeons to discriminate between achromatic male and female human faces demonstrated the effectiveness of the procedure. In contrast to 12 pigeons that show little improvement over 60 hr of go/no-go discrimination training, 14 multiple-matching pigeons mastered the problem within a few hours.