Unlocking the symmetric transfer of irrelevant information: gene-environment interplay and enhanced interhemispheric cross-talk.

Hemispheric specialization influences stimulus processing and behavioural control, affecting responses to relevant stimuli. However, most sensory input is irrelevant and must be filtered out to prevent interference with task-relevant behaviour, a process known as habituation. Despite habituation's vital role, little is known about hemispheric specialization for this brain function.

Knowledge of lateralized brain function can contribute to animal welfare.

The specialized functions of each hemisphere of the vertebrate brain are summarized together with the current evidence of lateralized behavior in farm and companion animals, as shown by the eye or ear used to attend and respond to stimuli. Forelimb preference is another manifestation of hemispheric lateralization, as shown by differences in behavior between left- and right-handed primates, left- and right-pawed dogs and cats, and left- and right-limb-preferring horses. Left-limb preference reflects right hemisphere use and is associated with negative cognitive bias.

Unfolding a sequence of sensory influences and interactions in the development of functional brain laterality.

Evidence of sensory experience influencing the development of lateralized brain and behavior is reviewed. The epigenetic role of light exposure during two specific stages of embryonic development of precocial avian species is a particular focus of the research discussed. Two specific periods of light sensitivity (in early versus late incubation), each depending on different subcellular and cellular processes, affect lateralized behavior after hatching.

Lateralized motor behaviour in the righting responses of the cane toad ().

This paper reports a series of tests for fore- and hind-limb preferences used by cane toads, , to assist returning to the righted position after being overturned. We confirm the strong and significant right-handedness reported in this species, which under certain conditions exceeded 90% right-hand preference at the group level. Toads were tested under a variety of conditions including horizontal and inclined surfaces, with and without the opportunity for the forelimbs to grasp a support, in order to assess the effects of different vestibular and proprioceptive input on the strength and direction of fore- and hind-limb preferences.

Brain Lateralization and Cognitive Capacity.

One way to increase cognitive capacity is to avoid duplication of functions on the left and right sides of the brain. There is a convincing body of evidence showing that such asymmetry, or lateralization, occurs in a wide range of both vertebrate and invertebrate species. Each hemisphere of the brain can attend to different types of stimuli or to different aspects of the same stimulus and each hemisphere analyses information using different neural processes.

A function for the bicameral mind.

Why do the left and right sides of the brain have different functions? Having a lateralized brain, in which each hemisphere processes sensory inputs differently and carries out different functions, is common in vertebrates, and it has now been reported for invertebrates too. Experiments with several animal species have shown that having a lateralized brain can enhance the capacity to perform two tasks at the same time. Thus, the different specializations of the left and right sides of the brain seem to increase brain efficiency.

Complementary Specializations of the Left and Right Sides of the Honeybee Brain.

Honeybees show lateral asymmetry in both learning about odors associated with reward and recalling memory of these associations. We have extended this research to show that bees exhibit lateral biases in their initial response to odors: viz., turning toward the source of an odor presented on their right side and turning away from it when presented on their left side.

Howard I. Kushner's .

.

Manual bias, behavior, and cognition in common marmosets and other primates.

This chapter examines the importance of studying hand preference together with different expressions of behavior. Cognitive differences between left- and right-handed primates are discussed. As shown in several species of primate, eye preference, but not hand preference, is biased at the level of the population and reflects hemispheric asymmetry of processing.

Food Calls in Common Marmosets, , and Evidence That One Is Functionally Referential.

We studied three calls of common marmosets, , elicited in the context of food. Call A, but not B or C, had been described previously as a food call. We presented insects (live mealworms or crickets) and fruit (banana or blueberries) and used playbacks of calls.

Influence of exposure in ovo to different light wavelengths on the lateralization of social response in zebrafish larvae.

Exposure of the chick embryo to different wavelengths of light of the same intensity has shown that only certain wavelengths may be important in generating visual asymmetries. This study aimed to detect the possible influence of different wavelengths of light on development of asymmetry of social recognition in zebrafish larvae, tested using the fish's mirror image as the stimulus. From fertilization until day 10 post-hatching zebrafish were kept in five different lighting conditions: natural light/dark (LD) cycle, complete darkness (DD), and artificial LD cycles with 14 h of monochromatic light (red, green, or violet light) and 10 h of darkness (rLD 14:10, gLD 14:10, vLD 14:10, respectively).

Cognitive bias, hand preference and welfare of common marmosets.

Common marmosets (Callithrix jacchus) have hand preferences for grasping pieces of food and holding them while eating and these are stable throughout adult life. We report here that left-handed marmosets have negative cognitive bias compared to right-handed marmosets. Twelve marmosets were trained to expect a food reward from a bowl with a black lid and not from one with a white lid, or vice versa.

Is painting by elephants in zoos as enriching as we are led to believe?

The relationship between the activity of painting and performance of stereotyped and other stress-related behaviour was investigated in four captive Asian elephants at Melbourne Zoo, Australia. The activity involved the elephant being instructed to paint on a canvas by its keeper in front of an audience. Painting by elephants in zoos is commonly believed to be a form of enrichment, but this assumption had not been based on any systematic research.

The magnetic compass of domestic chickens.

In a recent paper, we showed that domestic chickens can be trained to search for a social stimulus in specific magnetic directions. Chickens can hardly fly and have only small home ranges, hence their having a functional magnetic compass may seem rather surprising. Yet considering the natural habitat of their ancestors and their lifestyle until recently, the advantages of a magnetic compass become evident.

Asymmetry of brain and behavior in animals: Its development, function, and human relevance.

Since the discovery of brain asymmetry in a wide range of vertebrate species, it has become possible to study development and expression of lateralized behavior accurately in well-controlled experiments. Several species have emerged as useful models for investigating aspects of lateralization. Discussed here are: (1) the influence of exposure to light during embryonic development on lateralization, (2) effects of steroid hormones on lateralization, (3) developmental changes in which hemisphere is controlling behavior, and (4) asymmetry in memory formation and recall.

The Bee as a Model to Investigate Brain and Behavioural Asymmetries.

The honeybee Apis mellifera, with a brain of only 960,000 neurons and the ability to perform sophisticated cognitive tasks, has become an excellent model in life sciences and in particular in cognitive neurosciences. It has been used in our laboratories to investigate brain and behavioural asymmetries, i.e.

Stability of referential signalling across time and locations: testing alarm calls of Australian magpies (Gymnorhina tibicen) in urban and rural Australia and in Fiji.

In many avian species, vocal repertoire expands and changes throughout life as new syllables are added and sounds adapted to neighbours and circumstances. Referential signals, on the other hand, demand stability and lack of variation so that their meaning can be understood by conspecifics at all times. It is not known how stable such signals may be when the context is changed entirely but the point of reference remains unchanged.

A right antenna for social behaviour in honeybees.

Sophisticated cognitive abilities have been documented in honeybees, possibly an aspect of their complex sociality. In vertebrates brain asymmetry enhances cognition and directional biases of brain function are a putative adaptation to social behaviour. Here we show that honeybees display a strong lateral preference to use their right antenna in social interactions.

Ontogenetic development of magnetic compass orientation in domestic chickens (Gallus gallus).

Domestic chickens (Gallus gallus) can be trained to search for a social stimulus in a specific magnetic direction, and cryptochrome 1a, found in the retina, has been proposed as a receptor molecule mediating magnetic directions. The present study combines immuno-histochemical and behavioural data to analyse the ontogenetic development of this ability. Newly hatched chicks already have a small amount of cryptochrome 1a in their violet cones; on day 5, the amount of cryptochrome 1a reached the same level as in adult chickens, suggesting that the physical basis for magnetoreception is present.

Left-right asymmetries of behaviour and nervous system in invertebrates.

Evidence of left-right asymmetries in invertebrates has begun to emerge, suggesting that lateralization of the nervous system may be a feature of simpler brains as well as more complex ones. A variety of studies have revealed sensory and motor asymmetries in behaviour, as well as asymmetries in the nervous system, in invertebrates. Asymmetries in behaviour are apparent in olfaction (antennal asymmetries) and in vision (preferential use of the left or right visual hemifield during activities such as foraging or escape from predators) in animals as different as bees, fruitflies, cockroaches, octopuses, locusts, ants, spiders, crabs, snails, water bugs and cuttlefish.

Origins of brain asymmetry: lateralization of odour memory recall in primitive Australian stingless bees.

Left-right antennal asymmetry has been reported in honeybees. We studied primitive social bees to investigate the evolutionary origins of the asymmetry. Three species of Australian native, stingless bees (Trigona carbonaria, Trigona hockingsi and Austroplebeia australis) were trained to discriminate two odours, lemon (+)/vanilla (-), using the Proboscis Extension Reflex (PER).

Differences in social and vocal behavior between left- and right-handed common marmosets (Callithrix jacchus).

Common marmosets (Callithrix jacchus) show either a left- or right-hand preference for reaching to pick up food and they retain the same preference throughout adult life. We compared the behavior of 10 right-handed and 10 left-handed marmosets, matched for age and sex. They were presented with live crickets both when alone and when in their social group.

Sexing the brain: the science and pseudoscience of sex differences.

A recent upsurge in unitary biological explanations for gender differences in behavior (i.e. that they are "hard-wired" in the genetic code), put forward not only in books written for a general audience but also in scientific papers, makes it important to examine the fallacies of these ideas.