In this study we examined the effects of 5-HT1A ligands in rats trained to discriminate 0.16 mg/kg i.p. 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) from saline in a two-lever, fixed ratio (FR)10 schedule of food reinforcement, and in pigeons trained to discriminate 0.31 mg/kg i.m. 8-OH-DPAT from saline in a two-key, FR30 schedule of food reinforcement. In both species, 8-OH-DPAT and a va...

This discriminative effects of cyclorphan were studied in pigeons trained to discriminate 0.32 mg/kg ethylketazocine, 1.8 mg/kg cyclazocine, or 32 mg/kg naltrexone from saline. A fourth group of pigeons was administered 100 mg/kg/day morphine and trained to discriminate 0.1 mg/kg naltrexone from saline. Cyclorphan produced dose-related ethylketazocine-appropriate responding that reached a maxim...

Three experiments that were carried out in series with 5 pigeons used novel training methods to investigate the rapid visual processing of picture stimuli by pigeons. On each trial, a sequence containing 1 of 2 bird pictures (the target) and nontarget bird pictures (the distractors) was presented. After the termination of the last item in the sequence, the pigeons were required to choose 1 of 2...

This study was conducted to determine the effect of age on blood biochemical profile of racing pigeons (Columba livia domestica) in Egypt. One hundred healthy racing pigeons of five different age groups (week old, 2 week old, 3 week old, 4 week old as young age and 30 week old as adult age) were used in this experiment. Blood values of packed cell volume (PCV), hemoglobin (Hb), differential leu...

Recent theoretical and empirical developments in human category learning have differentiated an analytic, rule-based system of category learning from a nonanalytic system that integrates information across stimulus dimensions. In the present study, the researchers applied this theoretical distinction to pigeons' category learning. Pigeons learned to categorize stimuli varying in the tilt and wi...

Spontaneous activity from 120 vestibular semicircular canal (SC) primary afferents and driven responses from 20 SC primary afferents to 2.3-decade bandwidth (0.029-6.152 Hz) sum of sinusoidal angular rotations were characterized in 10 unanesthetized pigeons. The results were compared with those previously gathered from barbiturate anesthetized pigeons. The average spontaneous mean firing rate (...

The authors used a touch screen-based visual-search task to investigate spatial integration in pigeons. First, pigeons were presented with a consistent spatial relationship between compound visual landmarks (LMs) A-X and B-Y, separately. Next, pigeons learned to find a hidden goal on the monitor in the presence of LMs A and B. The goal bore a consistent spatial relationship to LM A, but not to ...

BACKGROUND Pathogens with the zoonotic potential to infect humans, such as Campylobacter jejuni, Campylobacter coli and Chlamydophila psittaci, can be found in feral pigeons (Columba livia). Given the high density of these birds in the public parks and gardens of most cities, they may pose a direct threat to public health. METHODS A total of 118 pigeons were captured in three samplings carrie...

Two experiments examined the acquisition and transfer of a complex same-different discrimination by pigeons. With the use of a 2-alternative choice task, 5 pigeons were reinforced for discriminating odd-item Different displays in which a contrasting target ws present, from Same displays, in which all elements were identical. Four different types of same-different displays were concurrently test...

An avian analogue to human artificial or synthetic grammar learning (Reber, 1967) was developed. Pigeons viewed horizontal strings of three to eight colored letters. These strings either conformed to Reber's artificial grammar or violated it in one or two locations. Pigeons categorized the letter strings as grammatical (left keypeck) or nongrammatical (right keypeck). Overall accuracy of catego...