Early- and Late-Light Embryonic Stimulation Modulates Similarly Chicks\u2019 Ability to Filter out Distractors

Chicks (Gallus gallus) learned to run from a starting box to a target located at the end of a runway. At test, colourful and bright distractors were placed just outside the starting box. Dark incubated chicks (maintained in darkness from fertilization to hatching) stopped significantly more often, assessing more the left-side distractor than chicks hatched after late (for 42 h during the last three days before hatching) or early (for 42 h after fertilization) exposure to light. The results show that early embryonic light stimulation can modulate this particular behavioural lateralization comparably to the late application of it, though via a different route

A review of environmental enrichment for laying hens during rearing in relation to their behavioral and physiological development

Globally, laying hen production systems are a focus of concern for animal welfare. Recently, the impacts of rearing environments have attracted attention, particularly with the trend toward more complex production systems including aviaries, furnished cages, barn, and free-range. Enriching the rearing environments with physical, sensory, and stimulatory additions can optimize the bird's development but commercial-scale research is limited. In this review, “enrichment” is defined as anything additional added to the bird's environment including structurally complex rearing systems. The impacts of enrichments on visual development, neurobehavioral development, auditory stimulation, skeletal development, immune function, behavioral development of fear and pecking, and specifically pullets destined for free-range systems are summarized and areas for future research identified. Visual enrichment and auditory stimulation may enhance neural development but specific mechanisms of impact and suitable commercial enrichments still need elucidating. Enrichments that target left/right brain hemispheres/behavioral traits may prepare birds for specific types of adult housing environments (caged, indoor, outdoor). Similarly, structural enrichments are needed to optimize skeletal development depending on the adult layer system, but specific physiological processes resulting from different types of exercise are poorly understood. Stimulating appropriate pecking behavior from hatch is critical but producers will need to adapt to different flock preferences to provide enrichments that are utilized by each rearing group. Enrichments have potential to enhance immune function through the application of mild stressors that promote adaptability, and this same principle applies to free-range pullets destined for variable outdoor environments. Complex rearing systems may have multiple benefits, including reducing fear, that improve the transition to the layer facility. Overall, there is a need to commercially validate positive impacts of cost-effective enrichments on bird behavior and physiology

Neuronal circuits underlying visual attention during naturalistic behaviour in zebrafish larvae

To survive, animals need to sustain behavioural responses towards specific environmental stimuli to achieve an overall goal. One example is the hunting behaviour of zebrafish larvae, which is characterised by a set of discrete visuomotor events that begin with prey detection, followed by target-directed swims and end with prey capture. Several studies have begun elucidating the neuronal circuits that govern prey detection and initiation of hunting routines, which are largely dependent on the midbrain optic tectum (OT). However, it is not known how the brain is able to sustain a behavioural routine directed towards a specific target, especially in complex environments containing distractors. In this study, I have discovered that the nucleus isthmus (NI), a midbrain nucleus implicated in visual attention in other vertebrates, is required for sustained tracking of prey during hunting routines in zebrafish larvae. NI neurons co-express cholinergic and glutamatergic markers and possess two types of axonal projection morphology. The first type targets the ipsilateral OT and AF7, a retinorecipient pretectal region involved in hunting. The second type projects bilaterally to the deep OT layers. Laser ablation of the NI followed by tracking of naturalistic hunting behaviour, revealed that while hunting initiation rates and motor kinematics were unaltered, ablated animals showed an elevated probability of aborting hunting routines midway. Moreover, 2-photon calcium imaging of tethered larvae during a closed-loop virtual reality hunting assay, showed that NI neurons are specifically active during hunting. These results suggest that the NI supports the maintenance of action sequences towards specific prey targets during hunting, most likely by modulating pretectal and tectal activity. This in turn supports its presence at the centre of an evolutionarily conserved circuit to control selective attention to ethologically relevant stimuli in the presence of competing distractors

Early- and Late-Light Embryonic Stimulation Modulates Similarly Chicks’ Ability to Filter out Distractors

Chicks (Gallus gallus) learned to run from a starting box to a target located at the end of a runway. At test, colourful and bright distractors were placed just outside the starting box. Dark incubated chicks (maintained in darkness from fertilization to hatching) stopped significantly more often, assessing more the left-side distractor than chicks hatched after late (for 42 h during the last three days before hatching) or early (for 42 h after fertilization) exposure to light. The results show that early embryonic light stimulation can modulate this particular behavioural lateralization comparably to the late application of it, though via a different route

The mechanisms underlying convergent evolution in the plumage patterns of birds

Convergent evolution is a central theme in biology. Birds are an ideal system to examine the mechanisms underlying convergent evolution. Although bird patterning is diverse, within-feather patterns have repeatedly converged on the same four types: mottled patterns, scales, bars and spots. Other avian patterns occur, e.g. stripes, but are rare. In my thesis I examine the four main mechanisms underlying convergent evolution in plumage patterns: evolutionary genetics, evolutionary development, natural selection for signaling and camouflage. Japanese quail (Coturnix japonica) is a model system in developmental biology. Examining the developmental basis of pattern formation using molecular techniques, the dorsal patterning of embryonic quail is likely due to activation of the melanocortin-1 receptor, which is a highly conserved pathway in vertebrates. I examined whether a reaction-diffusion based theoretical model of pattern formation may predict developmental constraint in two groups that have different lifestyles and spectacular patterns: waterfowl (Anseriformes) and gamebirds (Galliformes). Tracing the evolutionary trajectory of pattern evolution with Bayesian comparative modeling there was evidence for developmental constraint in pattern evolution. Adaptive explanations may also result in convergence. Cuckoo-hawk mimicry has been demonstrated in the common cuckoo (Cuculus canorus) and the Eurasian sparrowhawk (Accipiter nisus), but may be prevalent in Old World cuckoos. Randomly selecting a parasitic cuckoo from each genera of Old World cuckoos and <8 sympatric raptors, I quantified their barred patterns using digital image analysis and found that parasitism can explain convergent evolution in the patterns of parasitic cuckoos and raptors. Patterns may have evolved due to ecological selection. Examining the patterns of 80% of all avian species worldwide, I found that habitat does not predict patterning, and that all four patterns are found in all habitats. These results demonstrate that the mechanisms of convergent evolution are diverse, and that development and natural selection have contributed to pattern evolution.The Cambridge Commonwealth, European and International Trust, the John Stanley Gardiner Fund, and the Pembroke college graduate research fund

Serotonergic modulation of the ventral pallidum by 5HT1A, 5HT5A, 5HT7 AND 5HT2C receptors

Introduction: Serotonin's involvement in reward processing is controversial. The large number of serotonin receptor sub-types and their individual and unique contributions have been difficult to dissect out, yet understanding how specific serotonin receptor sub-types contribute to its effects on areas associated with reward processing is an essential step. Methods: The current study used multi-electrode arrays and acute slice preparations to examine the effects of serotonin on ventral pallidum (VP) neurons. Approach for statistical analysis: extracellular recordings were spike sorted using template matching and principal components analysis, Consecutive inter-spike intervals were then compared over periods of 1200 seconds for each treatment condition using a student’s t test. Results and conclusions: Our data suggests that excitatory responses to serotonin application are pre-synaptic in origin as blocking synaptic transmission with low-calcium aCSF abolished these responses. Our data also suggests that 5HT1a, 5HT5a and 5HT7 receptors contribute to this effect, potentially forming an oligomeric complex, as 5HT1a antagonists completely abolished excitatory responses to serotonin application, while 5HT5a and 5HT7 only reduced the magnitude of excitatory responses to serotonin. 5HT2c receptors were the only serotonin receptor sub-type tested that elicited inhibitory responses to serotonin application in the VP. These findings, combined with our previous data outlining the mechanisms underpinning dopamine's effects in the VP, provide key information, which will allow future research to fully examine the interplay between serotonin and dopamine in the VP. Investigation of dopamine and serotonins interaction may provide vital insights into our understanding of the VP's involvement in reward processing. It may also contribute to our understanding of how drugs of abuse, such as cocaine, may hijack these mechanisms in the VP resulting in sensitization to drugs of abuse

2021 Student Symposium Research and Creative Activity Book of Abstracts

The UMaine Student Symposium (UMSS) is an annual event that celebrates undergraduate and graduate student research and creative work. Students from a variety of disciplines present their achievements with video presentations. It’s the ideal occasion for the community to see how UMaine students’ work impacts locally – and beyond. The 2021 Student Symposium Research and Creative Activity Book of Abstracts includes a complete list of student presenters as well as abstracts related to their works