ABSTRACT
Detour tests provide a reliable indicator of the presence of visual lateralisation. Previous studies on fishes and birds suggest that preferences in choosing to detour an obstacle to reach a goal are due to asymmetries of eye use. We studied detour behaviour to reach a prey in males of Podarcis muralis in order to ascertain visual laterality for a predatory task. Lizards were found to be lateralised at both individual and population levels, although only a few lizards were found to express lateralisation at the level of the individual. The preferential direction of detouring is the left route around a transparent barrier, indicating a right eye/left hemisphere use to observe the prey and confirming the results of recent work. The eye used to fixate the prey was maintained longer in the same direction the lizards subsequently chose to approach it, confirming that the preference was basically due to visual asymmetry, not to motor asymmetry. To our knowledge this is the first study of detouring conducted on sauria, demonstrating how these lizards are right eye/left hemisphere lateralised for predatory tasks at individual and population level.
Subject(s)
Behavior, Animal/physiology , Functional Laterality/physiology , Lizards , Predatory Behavior/physiology , Animals , Male , Visual Fields/physiology , Visual Perception/physiologyABSTRACT
Ectotherms have been shown being lateralized as well as mammals and birds. This is particularly evident in visual lateralization, i.e. the different use of the eyes, leading to use a specific eye to observe specific kind of stimuli and to process them with the correspondent contralateral hemisphere. Several lower vertebrates are facilitated in this from the lateral position of the eyes, enabling them to carry out more tasks simultaneously, controlled by different eyes and relative hemispheres. Predatory responses seem usually mediated by the right eye/left hemisphere in fishes, amphibians and some sauropsids, but there are no strong evidences of this in lizards. Eighteen wild males of the Common wall lizard Podarcis muralis were tested individually in captivity to ascertain whether they are lateralized to look at prey with a specific eye. The lizards were gently induced entering a 30-cm long central arm of a T-maze which led to a 44.5-cm long arm cross-arm at whose extremities there were two identical prey, Tenebrio molitor larvae, familiar to the lizards. We recorded what direction the lizards chose to reach the prey and the frequency and duration of head turning, indicative of looking either prey with the left or the right eye. We found that individuals show being lateralized at individual level. The preferred direction taken to reach the prey is the right for the majority of those (4 of 5) showing an evident preference, indicating also a possible form of laterality at population level. In addition, lizards maintained the same head side of the direction taken turned for more time towards the prey than the opposite head side, revealing an eye preference for observing this kind of cue. Our study demonstrates how males of Podarcis muralis have a visual lateralization to capture prey. Furthermore, it is another support to the hypothesis of vertebrate lateralization derivation from a common ancestor.
Subject(s)
Behavior, Animal/physiology , Functional Laterality/physiology , Lizards/physiology , Predatory Behavior/physiology , Analysis of Variance , Animals , Male , Photic Stimulation/methods , Visual Fields/physiology , Visual Perception/physiologySubject(s)
Medicine , Physician-Patient Relations , Physicians, Family , Specialization , Ethics, Medical , Family Practice , Humans , Italy , Philosophy, Medical , Physicians, WomenSubject(s)
Thinness , Adolescent , Adult , Animals , Anorexia/etiology , Anorexia Nervosa/diagnosis , Anorexia Nervosa/metabolism , Anorexia Nervosa/physiopathology , Body Composition , Body Temperature Regulation , Cachexia/etiology , Child , Diet , Female , Humans , Male , Obesity/etiology , Obesity/metabolism , Obesity/physiopathology , Rats , Thinness/etiology , Thinness/metabolism , Thinness/physiopathologySubject(s)
Aprotinin/administration & dosage , Cysts/therapy , Factor XIII/administration & dosage , Fibrinogen/administration & dosage , Thrombin/administration & dosage , Thyroid Diseases/therapy , Tissue Adhesives/administration & dosage , Adult , Cysts/diagnosis , Drug Combinations/administration & dosage , Evaluation Studies as Topic , Fibrin Tissue Adhesive , Humans , Middle Aged , Thyroid Diseases/diagnosis , UltrasonographyABSTRACT
Relatively recent data from the literature show some discrepancies between bioactive LH (Bio-LH) and radioimmunoreactive LH (Ria-LH) in different endocrinological conditions. In 202 subjects of both sexes we have studied biologically active and immunoreactive LH and their ratio (B/l ratio) pattern through life. The results show that in male puberty the in vitro bioassay method gives a more discriminating measurement of serum LH than the radioimmunoassay. The ratio between bioactive and immunoreactive LH is well correlated with the increase of serum testosterone levels from male prepuberty to adulthood. On the contrary, there is no difference of B/l ratio between prepubertal girls and fertile women, in spite of the different gonadotropin levels. Finally LH bioactivity increases less markedly in elderly men than in postmenopausal women. These data suggest that, among several factors which may influence not only the quantity but also the quality of LH secreted, gonadotropin secretion rate and sex steroid milieu play an important role and may partly explain the B/l ratio changes in the situations investigated.
