|
Rogers, L. J. (2017). A Matter of Degree: Strength of Brain Asymmetry and Behaviour. Symmetry, 9(4).
Abstract: Research on a growing number of vertebrate species has shown that the left and right sides of the brain process information in different ways and that lateralized brain function is expressed in both specific and broad aspects of behaviour. This paper reviews the available evidence relating strength of lateralization to behavioural/cognitive performance. It begins by considering the relationship between limb preference and behaviour in humans and primates from the perspectives of direction and strength of lateralization. In birds, eye preference is used as a reflection of brain asymmetry and the strength of this asymmetry is associated with behaviour important for survival (e.g., visual discrimination of food from non-food and performance of two tasks in parallel). The same applies to studies on aquatic species, mainly fish but also tadpoles, in which strength of lateralization has been assessed as eye preferences or turning biases. Overall, the empirical evidence across vertebrate species points to the conclusion that stronger lateralization is advantageous in a wide range of contexts. Brief discussion of interhemispheric communication follows together with discussion of experiments that examined the effects of sectioning pathways connecting the left and right sides of the brain, or of preventing the development of these left-right connections. The conclusion reached is that degree of functional lateralization affects behaviour in quite similar ways across vertebrate species. Although the direction of lateralization is also important, in many situations strength of lateralization matters more. Finally, possible interactions between asymmetry in different sensory modalities is considered.
|
|
|
Rogers, L. J. (2002). Advantages and disadvantages of lateralization. In L. J. Rogers, & R. Andrew (Eds.), (pp. 126–153). New York: Cambridge University Press.
|
|
|
Austin, N. P., & Rogers, L. J. (2007). Asymmetry of flight and escape turning responses in horses. Laterality, 12(5), 464–474.
Abstract: We investigated whether horses display greater reactivity to a novel stimulus presented in the left compared to the right monocular visual field, and whether a population bias exists for escape turning when the same stimulus was presented binocularly. Domestic horses (N=30) were tested on three occasions by a person opening an umbrella five metres away and then approaching. The distance each horse moved away before stopping was measured. Distance was greatest for approach on the left side, indicating right hemisphere control of flight behaviour, and thus followed the same pattern found previously in other species. When order of monocular presentation was considered, an asymmetry was detected. Horses tested initially on the left side exhibited greater reactivity for left approach, whereas horses tested on the right side first displayed no side difference in reactivity. Perhaps left hemisphere inhibition of flight response allowed horses to learn that the stimulus posed no threat and this information was transferred to the right hemisphere. No population bias existed for the direction of escape turning, but horses that turned to the right when approached from the front were found to exhibit longer flight distances than those that turned to the left.
|
|
|
Rogers, L. (2020). Asymmetry of Motor Behavior and Sensory Perception: Which Comes First? Symmetrie, 12(5), 690.
Abstract: By examining the development of lateralization in the sensory and motor systems of the human fetus and chick embryo, this paper debates which lateralized functions develop first and what interactions may occur between the different sensory and motor systems during development. It also discusses some known influences of inputs from the environment on the development of lateralization, particularly the effects of light exposure on the development of visual and motor lateralization in chicks. The effects of light on the human fetus are related in this context. Using the chick embryo as a model to elucidate the genetic and environmental factors involved in development of lateralization, some understanding has been gained about how these lateralized functions emerge. At the same time, the value of carrying out much more research on the development of the various types of lateralization has become apparent.
|
|
|
Siniscalchi, M., McFarlane, J. R., Kauter, K. G., Quaranta, A., & Rogers, L. J. (2013). Cortisol levels in hair reflect behavioural reactivity of dogs to acoustic stimuli. Research in Veterinary Science, 94(1), 49–54.
Abstract: Cortisol levels in hair samples were examined in fourteen domestic dogs and related to the dogs’ responses to different acoustic stimuli. Stimuli were playbacks of species-typical vocalizations recorded during three different situations (“disturbance”, “isolation” and “play” barks) and the sounds of a thunderstorm. Hair samples were collected at 9:00 h and 17:00 h two weeks after the behavioural tests. Results showed that behavioural reactivity to playback of the various stimuli correlates with cortisol levels in hair samples collected at 9:00 h, and the same was the case for the separate measures of behaviour (i.e. hiding, running away, seeking attention from the tester, panting and lowering of the body posture). Hence, levels of cortisol in hair appear to reflect the dog’s chronic state of emotional reactivity, or temperament.
|
|
|
Rogers, L. J. (1997). Early Experiential Effects on Laterality: Research on Chicks has Relevance to Other Species. Laterality, 2(3-4), 199–219.
Abstract: The influence of early experience on the development of lateralisation of hemispheric function was further investigated, using the chick as a model. A range of functions are lateralised in the chick and these correlate with asymmetry in the organisation of the visual projections. Chicks using the right eye and, therefore, primarily the left hemisphere are able to switch from pecking randomly at grain and pebbles to pecking mainly at grain, whereas those using the left eye and primarily the right hemisphere continue to peck at random. Exposure to light during the last days of incubation establishes this lateralisation in males, as a consequence of the embryo being oriented in the egg so that the left eye only is occluded. Males incubated in the dark peck at random when using either the right or left eye. Irrespective of light experience, females perform the same as darkincubated males: they are not influenced by light exposure. Monocular performance of the pebble-grain task is compared to binocular performance, and the sensitive period for the influence of light is delineated. The interactive effects of sex hormone levels on the differentiation of lateralisation are discussed and also the relevance of the results to other species, including humans.
|
|
|
Rogers, L. J. (2000). Evolution of hemispheric specialization: advantages and disadvantages. Brain Lang, 73(2), 236–253.
Abstract: Lateralization of the brain appeared early in evolution and many of its features appear to have been retained, possibly even in humans. We now have a considerable amount of information on the different forms of lateralization in a number of species, and the commonalities of these are discussed, but there has been relatively little investigation of the advantages of being lateralized. This article reports new findings on the differences between lateralized and nonlateralized chicks. The lateralized chicks were exposed to light for 24 h on day 19 of incubation, a treatment known to lead to lateralization of a number of visually guided responses, and the nonlateralized chicks were incubated in the dark. When they were feeding, the lateralized chicks were found to detect a stimulus resembling a raptor with shorter latency than nonlateralized chicks. This difference was not a nonspecific effect caused by the light-exposed chicks being more distressed by the stimulus. Instead, it appears to be a genuine advantage conferred by having a lateralized brain. It is suggested that having a lateralized brain allows dual attention to the tasks of feeding (right eye and left hemisphere) and vigilance for predators (left eye and right hemisphere). Nonlateralized chicks appear to perform these dual tasks less efficiently than lateralized ones. Reference is made to other species in discussing these results.
|
|
|
Rogers, L. J. (2002). Evolution of Side Biases: Motor versus Sensory Lateralization. In M. K. Mandal, M. B. Bulman-Fleming, & G. Tiwari (Eds.), Side Bias: A Neuropsychological Perspective (3-p. 40). Springer Netherlands.
|
|
|
Crowley, P. H., Provencher, L., Sloane, S., Dugatkin, L. A., Spohn, B., Rogers, L., et al. (1996). Evolving cooperation: the role of individual recognition. Biosystems, 37(1-2), 49–66.
Abstract: To evaluate the role of individual recognition in the evolution of cooperation, we formulated and analyzed a genetic algorithm model (EvCo) for playing the Iterated Prisoner's Dilemma (IPD) game. Strategies compete against each other during each generation, and successful strategies contribute more of their attributes to the next generation. Each strategy is encoded on a `chromosome' that plays the IPD, responding to the sequences of most recent responses by the interacting individuals (chromosomes). The analysis reported in this paper considered different memory capabilities (one to five previous interactions), pairing continuities (pairs of individuals remain together for about one, two, five, or 1000 consecutive interactions), and types of individual recognition (recognition capability was maximal, nil, or allowed to evolve between these limits). Analysis of the results focused on the frequency of mutual cooperation in pairwise interactions (a good indicator of overall success in the IPD) and on the extent to which previous responses by the focal individual and its partner were associated with the partner's identity (individual recognition). Results indicated that a fixed, substantial amount of individual recognition could maintain high levels of mutual cooperation even at low pairing continuities, and a significant but limited capability for individual recognition evolved under selection. Recognition generally increased mutual cooperation more when the recent responses of individuals other than the current partner were ignored. Titrating recognition memory under selection using a fitness cost suggested that memory of the partner's previous responses was more valuable than memory of the focal's previous responses. The dynamics produced to date by EvCo are a step toward understanding the evolution of social networks, for which additional benefits associated with group interactions must be incorporated.
|
|
|
Siniscalchi, M., Quaranta, A., & Rogers, L. J. (2008). Hemispheric specialization in dogs for processing different acoustic stimuli. PloS ONE, 3, e3349.
|
|