We examined how explicit instructions to encode visual context information accompanying visually-presented unrelated target words affected later recognition of the targets presented alone, in younger and older adults. In Experiments 1 and 3, neutral context scenes, and in Experiments 2 and 4, emotionally salient context scenes, were paired with target words during encoding. Experiments 1 and 2 data were collected using within subject design; in Experiments 3 and 4 we used a between subjects design. Across all four experiments, instructions to explicitly make a link (associate) between simultaneously presented context and target words always led to significantly better recognition memory in both younger and older adults compared to deep or shallow levels of processing (LoP) instructions for the context information. In all experiments the age-related deficit in overall memory remained. There was no consistent difference in the effect of a shallow versus deep processing of context in the first three experiments in young adults, although a standard LoP effect, with better memory performance following deep than shallow processing, was demonstrated with both age groups in Experiment 4. Results suggest that an instruction to explicitly link target words to context information will significantly and consistently improve memory recognition for targets. This was demonstrated in all four experiments, in both younger and older adults. Importantly, results suggest that memory in older adults can be improved with specific instructional manipulations during encoding.

Repeated focal electrical stimulation of the brain results in kindling, the development of generalized seizures that progress in length and severity as more seizures are elicited. Barnes et al. (2001) paired one context (CS+) with kindling stimulation of the amygdala, and another context (CS-) with sham stimulation. They found conditioned anticipatory fear responses in the CS+, a conditioned place aversion to the CS+, and more intense convulsions in the CS+ than in the CS- in a probe trial. The present experiment was an attempt to replicate the findings, and to extend them by recording electroencephalographs (EEG). As well, I tested for conditioned effects on afterdischarge threshold (ADT). Rats received 45 pairings in each context before a conditioned place preference/aversion test, to determine whether the stimulation and seizures were rewarding or punishing. After more pairings, rats received suprathreshold stimulation in each context (switch test). Ictal measures in this test included afterdischarge duration, clonus duration, latency to clonus, class of convulsion, and falls. After more pairings, ADT was measured in each context. I partially replicated the findings of Barnes et al., in that conditioned anticipatory responses and conditioned place aversion were found. However, there were no conditioned effects on any ictal measures, including ADT. I conclude that conditioning is unlikely to play a major role in epileptogenesis.

There is a clearly established division of functional processing between left and right hemispheres of the brain, with the pattern showing robust consistency across individuals. The finding of functional differences between the hemispheres of the brain raises two important questions: First, what mechanisms gave rise to the lateralized biases in processing function? Second, what are the consequences of functional asymmetry of cognitive processing in the human brain on our everyday behaviour? Examining the mechanisms that give rise to cerebral lateralization, Experiments 1 and 2 tested the assumption that there is a causal relationship in the degree and direction of lateralization between left- and right-hemisphere dominant tasks. In experiment 1, this relationship between left-hemisphere processing of speech sounds and right-hemisphere processing of emotional vocalizations was examined using dichotic listening tasks. An overall complementary pattern of lateralization was observed across participants, but no significant relationship was found for degree of lateralization of speech and emotional vocalization processing within individuals. These results support the view that functions in the left and right hemispheres are independently lateralized. In Experiment 2 we examined the relationship pattern in degree of lateralization between linguistic processing and melody recognition using dichotic-listening tasks. The expected left-hemisphere advantage was observed for the linguistic processing task, but the expected right-hemisphere advantage was not observed for the melody recognition task, precluding an informative assessment of complementarity between the two tasks. The division of processing between the two hemispheres of the brain has been shown to result in lateralized performance advantages and behavioural biases. Examining these consequences of lateralization, Experiments 3 through 6 explored the influence of lateral biases on everyday behaviour. Experiments 3 and 4 examined the influence of asymmetries in facial attractiveness on posing biases. Despite evidence suggesting that the right side of the face is found to be more attractive, professional modeling photographs examined in Experiment 3 revealed a leftward posing bias suggesting that asymmetries in facial attractiveness are not dominant in influencing posing behaviour, even when the purpose of the image is to highlight attractiveness. Experiment 4 controlled for image selection biases by examining posing behaviour directly and revealed a rightward posing bias when participants were asked to emphasize their attractiveness. Experiments 5 and 6 examined the influence of lateralized cognitive processing demands on seating preferences. Experiment 5 investigated the real-world seating patterns of theatre patrons during actual film screenings. It was found that, when processing expectations relied on right-hemisphere dominant processes, such as emotional, facial, or visuospatial processing, people were more likely to choose a seat to the right side of the room. Experiment 6 was designed to test two competing theories that have attempted to explain seating biases: one posits that expectation of processing demand drives the bias; the other posits that basic motor asymmetries drive the bias. Through naturalistic observation, I recorded classroom-seating choices of university students using photographs. When processing expectations relied on left-hemisphere dominant processes, such as linguistic processing, people were more likely to choose seats on the left side of the classroom; this finding contrasts the right side bias observed in theatre seating studies, providing evidence that expectation of processing demands influences the seating bias. Addressing the mechanisms that guide the evolution of lateralization, no support for the assumption of a causal relationship between complementary left-and right-lateralized cognitive functions was found. Additionally, examination of asymmetries in everyday behaviours such as seating and posing provide evidence that the lateralization of cognitive functions has a direct influence on human behaviour and interaction with the environment.

The neuroendocrine basis of paternal behaviour is hypothesised to be homologous to that of maternal behaviour, with the expression of paternal behaviour resulting from the activation of estrogen-sensitive pathways in the brain. However, despite the fact that Phodopus campbelli fathers are highly paternal, previous studies have failed to identify an activational role for estradiol in the expression of this behaviour. The goal of this thesis was to exclude or define a role for estradiol in P. campbelli paternal behaviour. In the first study, estrogen receptor alpha (ERα) expression was examined in three brain regions relevant to maternal behaviour (medial preoptic area, bed nucleus of the stria terminalis, and medial amygdala). Male and female P. campbelli and its close relative P. sungorus were sampled as sexually naïve adults, following mating to satiety, or as new parents. As predicted, new fathers of either species did not upregulate ERα expression in these brain regions. Mating also had no effect on ERα expression in males or females from either species. However, ERα expression was also not upregulated in any of the three brain regions in new mothers. Thus, it is possible that estradiol does not play a primary role in activating maternal behaviour in Phodopus females. In the second study, P. campbelli males were administered the aromatase inhibitor letrozole at three different developmental stages (independence from the mother, testicular maturation, and sexually naïve adult) and tested for adult sexual and paternal behaviour. Aromatase inhibition during juvenile development resulted in diminished expression of adult paternal and sexual behaviour, suggesting that estradiol acts at critical periods in development to organize the paternal brain for subsequent behavioural responses. Treatment of sexually naïve adults did not alter male behaviour, which further supports previous evidence that estradiol does not activate paternal behaviour in P. campbelli males, although sexual behaviour in females is completely estradiol-dependent in this species. These findings suggest that the activational roles of estradiol in maternal and male sexual behaviour identified in the rat do not generalize to Phodopus, and imply greater species to species variation in the neuroendocrine control of these behaviours than previously suspected. / Thesis (Ph.D, Biology) -- Queen's University, 2008-09-15 10:52:00.161

In their natural environment animals must balance their safety requirements (i.e., avoiding predation) with their need to satisfy their energy demands (i.e., securing food). How the brain integrates these competing demands to promote adaptive responding is not well understood. The current study examined the effects of chronic food restriction on rats' behavioural defense profiles in two animal models of anxiety; the shock-probe burying and elevated plus-maze tests. In agreement with previous research, food restriction dramatically increased rats' open-arm exploration in the plus-maze. By contrast, food restriction did not alter the duration of time rats spent burying an electrified probe in the shock-probe burying test. Furthermore, food restricted rats displayed increases in risk assessment behaviour in both tests. Animals’ behaviour in both animal models of anxiety does not suggest a food-restriction induced reduction in anxiety. Alternatively, the results suggest that rats' willingness to explore normally avoided open arenas is sensitive to their current energy demands. In particular, it appears that under conditions of food scarcity rodents adapt their defensive profiles in order to meet both safety needs and satisfy energy demands. Further, the dramatic shift in open-arm exploration displayed by food-restricted animals seems to involve activation (as indexed by cFos) of brain regions previously implicated in feeding behaviour and normal open arm avoidance. Notably, an interaction effect of feeding and testing was observed in the anterior basolateral amygdala. This nucleus may be involved in integrating the competing demands of safety and energy requirements. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2008-09-18 16:58:44.385

The role of semiochemicals in the behaviour and biology of <I>Lepeophtheirus salmonis</I> was investigated using a range of techniques. The potential use of semiochemicals in the behavioural ecology of mobile stages was examined using longitudinal monitoring and experimental manipulation of laboratory reared single cohort populations. The chronic and long term effects of separation from the host were also investigated using similar populations. The nature and chemosensory capability of the sense system of the parasite was assessed through morphological and ultrastructural studies. Finally, the nature of potential chemical stimuli during initial copepodid settlement, pair formation and mating, and host re-attachment of mobile stages, was examined using both <I>in vitro</I> and <I>in vivo</I> techniques. Longitudinal monitoring of populations created a model for mobile development and the timing and processes of pair formation and mating. There was evidence of a hierarchy of pair formation between female stages, periods of strong mate competition between males, and many factors within the processes were defined. Survival off the host was strongly related to the developmental stage and/or size of the louse; with adult females surviving for the longest and preadult I males for the shortest periods. The ability of adult males to re-attach and subsequently persist on the host was significantly reduced after only 72 hours of separation. Very few potential chemosensory setae were found on the appendages examined, the exception to this being the antennule. Two distinct populations of setae on the distal (14 setae) and proximal (27 setae) articles of the antennule demonstrated a wide range of morphology. The internal organisation, innervation and ultrastructure of these antennular setae was examined in detail. The setae could be divided into at least 6 distinct categories, when the internal data were combined with the external morphology.

This study presented six typically developing children between the ages of five to eight with familiarization (baseline) in a mock scanner after which behavioural intervention ensued, in a non-concurrent multiple baseline design. The behavioural intervention included reinforcement for the contingency of lying motionless, and response cost (the removal of desirable stimuli) as a punishment contingency for movement. During baseline, all children showed a fair amount of head motion in the mock scanner. During intervention, small to large reductions in head motion were observed for five of the six participants. Therefore, use of the mock scanner and the reinforcement/punishment contingencies, may be an aid used prior to actual MRI/fMRI scans for children between the ages of five to eight: it is cost effective, may require only a session or two of intervention to be effective, and the potentially dangerous side effects and/or disabilities of sedation/anaesthesia can be avoided.

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