PhD student, Macquarie University
Comparing and contrasting the proximate mechanisms of insect sociality with vertebrate findings.
Today we can see many examples of group living in the animal kingdom, each varying in size and degree of cohesion, which is thought to correlate with the level of cognitive complexity required. Honey bees (Apis mellifera) live in large societies and continuously interact with thousands of nestmates to maintain the functioning of the colony via coordinated and altruistic actions, making them an excellent species to study the neurobiology of social behaviour.
My research focuses on uncovering the neural chemicals driving this gregarious instinct that leads to the formation and maintenance of their cooperative groups. I designed a new behavioural assay that assesses honey bee sociability and nestmate affiliation and used this to describe how they develop. We found that both honey bee sociability and nestmate affiliation depends on the social environment experienced as an adult, much like vertebrate species.
Currently I am combining this new assay with neuropharmacological treatments, to determine the role of various neurochemical systems in these behaviours. As more than thirty years of study has uncovered the dominant roles of oxytocin and dopamine in mammalian pair bond formation, and octopamine is implicated in the neuromodulation of insect aggression and social recognition, I will activate and inhibit these neural systems via agonist and antagonist injection into the bee brain.
Furthering our understanding of insect brain chemistry in relation to the formation and maintenance of their societies is important for developing strategies to improve the success and survival of this dominant pollinator species. For example, chemical stressors such as pesticides can be designed so as not to effect the neural systems involved in honey bee sociability. Moreover, these studies will provide new evidence for the debate around the social brain hypothesis that correlates brain size with social group size and individual cognitive ability. The development of this invertebrate sociability bioassay, that allows direct comparison with vertebrate studies, has major implications for uncovering the evolution of sociality.
Abstract: The arthropod central complex and vertebrate basal ganglia derive from embryonic basal forebrain lineages that are specified by an evolutionarily conserved genetic program leading to interconnected neuropils and nuclei that populate the midline of the forebrain-midbrain boundary region. In the substructures of both the central complex and basal ganglia, network connectivity and neuronal activity mediate control mechanisms in which inhibitory (GABAergic) and modulatory (dopaminergic) circuits facilitate the regulation and release of adaptive behaviors. Both basal ganglia and central complex dysfunction result in behavioral defects including motor abnormalities, impaired memory formation, attention deficits, affective disorders, and sleep disturbances. The observed multitude of similarities suggests deep homology of arthropod central complex and vertebrate basal ganglia circuitries underlying the selection and maintenance of behavioral actions.
Pub.: 13 Apr '13, Pinned: 30 Sep '17
Abstract: Proximate neural mechanisms that influence preferences for groups of a given size are almost wholly unknown. In the highly gregarious zebra finch (Estrildidae: Taeniopygia guttata), blockade of nonapeptide receptors by an oxytocin (OT) antagonist significantly reduced time spent with large groups and familiar social partners independent of time spent in social contact. Opposing effects were produced by central infusions of mesotocin (MT, avian homolog of OT). Most drug effects appeared to be female-specific. Across five estrildid finch species, species-typical group size correlates with nonapeptide receptor distributions in the lateral septum, and sociality in female zebra finches was reduced by OT antagonist infusions into the septum but not a control area. We propose that titration of sociality by MT represents a phylogenetically deep framework for the evolution of OT's female-specific roles in pair bonding and maternal functions.
Pub.: 15 Aug '09, Pinned: 30 Sep '17
Abstract: How, why, and when consciousness evolved remain hotly debated topics. Addressing these issues requires considering the distribution of consciousness across the animal phylogenetic tree. Here we propose that at least one invertebrate clade, the insects, has a capacity for the most basic aspect of consciousness: subjective experience. In vertebrates the capacity for subjective experience is supported by integrated structures in the midbrain that create a neural simulation of the state of the mobile animal in space. This integrated and egocentric representation of the world from the animal’s perspective is sufficient for subjective experience. Structures in the insect brain perform analogous functions. Therefore, we argue the insect brain also supports a capacity for subjective experience. In both vertebrates and insects this form of behavioral control system evolved as an efficient solution to basic problems of sensory reafference and true navigation. The brain structures that support subjective experience in vertebrates and insects are very different from each other, but in both cases they are basal to each clade. Hence we propose the origins of subjective experience can be traced to the Cambrian.
Pub.: 18 Apr '16, Pinned: 30 Sep '17
Abstract: Whether invertebrates exhibit positive emotion-like states and what mechanisms underlie such states remain poorly understood. We demonstrate that bumblebees exhibit dopamine-dependent positive emotion-like states across behavioral contexts. After training with one rewarding and one unrewarding cue, bees that received pretest sucrose responded in a positive manner toward ambiguous cues. In a second experiment, pretest consumption of sucrose solution resulted in a shorter time to reinitiate foraging after a simulated predator attack. These behavioral changes were abolished with topical application of the dopamine antagonist fluphenazine. Further experiments established that pretest sucrose does not simply cause bees to become more exploratory. Our findings present a new opportunity for understanding the fundamental neural elements of emotions and may alter the view of how emotion states affect decision-making in animals.
Pub.: 07 Oct '16, Pinned: 30 Sep '17
Abstract: The social brain hypothesis was proposed as an explanation for the fact that primates have unusually large brains for body size compared to all other vertebrates: Primates evolved large brains to manage their unusually complex social systems. Although this proposal has been generalized to all vertebrate taxa as an explanation for brain evolution, recent analyses suggest that the social brain hypothesis takes a very different form in other mammals and birds than it does in anthropoid primates. In primates, there is a quantitative relationship between brain size and social group size (group size is a monotonic function of brain size), presumably because the cognitive demands of sociality place a constraint on the number of individuals that can be maintained in a coherent group. In other mammals and birds, the relationship is a qualitative one: Large brains are associated with categorical differences in mating system, with species that have pairbonded mating systems having the largest brains. It seems that anthropoid primates may have generalized the bonding processes that characterize monogamous pairbonds to other non-reproductive relationships ('friendships'), thereby giving rise to the quantitative relationship between group size and brain size that we find in this taxon. This raises issues about why bonded relationships are cognitively so demanding (and, indeed, raises questions about what a bonded relationship actually is), and when and why primates undertook this change in social style.
Pub.: 04 Jul '09, Pinned: 30 Sep '17
Abstract: There is growing evidence that the neuropeptides oxytocin and vasopressin modulate complex social behavior and social cognition. These ancient neuropeptides display a marked conservation in gene structure and expression, yet diversity in the genetic regulation of their receptors seems to underlie natural variation in social behavior, both between and within species. Human studies are beginning to explore the roles of these neuropeptides in social cognition and behavior and suggest that variation in the genes encoding their receptors may contribute to variation in human social behavior by altering brain function. Understanding the neurobiology and neurogenetics of social cognition and behavior has important implications, both clinically and for society.
Pub.: 08 Nov '08, Pinned: 30 Sep '17
Abstract: Deficits in social interaction are important early markers for autism and related neurodevelopmental disorders with strong genetic components. Standardized behavioral assays that measure the preference of mice for initiating social interactions with novel conspecifics would be of great value for mutant mouse models of autism. We developed a new procedure to assess sociability and the preference for social novelty in mice. To quantitate sociability, each mouse was scored on measures of exploration in a central habituated area, a side chamber containing an unfamiliar conspecific (stranger 1) in a wire cage, or an empty side chamber. In a secondary test, preference for social novelty was quantitated by presenting the test mouse with a choice between the first, now-familiar, conspecific (stranger 1) in one side chamber, and a second unfamiliar mouse (stranger 2) in the other side chamber. Parameters scored included time spent in each chamber and number of entries into the chambers. Five inbred strains of mice were tested, C57BL/6J, DBA/2J, FVB/NJ, A/J and B6129PF2/J hybrids. Four strains showed significant levels of sociability (spend- ing more time in the chamber containing stranger 1 than in the empty chamber) and a preference for social novelty (spending more time in the chamber containing stranger 2 than in the chamber containing the now-familiar stranger 1). These social preferences were observed in both male and female mice, and in juveniles and adults. The exception was A/J, a strain that demonstrated a preference for the central chamber. Results are discussed in terms of potential applications of the new methods, and the proper controls for the interpretation of social behavior data, including assays for health, relevant sensory abilities and motor functions. This new standardized procedure to quantitate sociability and preference for social novelty in mice provides a method to assess tendencies for social avoidance in mouse models of autism.
Pub.: 04 Sep '04, Pinned: 30 Sep '17