Although most strepsirrhines do not exhibit apparent physical signs of sexually selected traits, researchers have suggested that olfactory communication is sexually selected. The goal of this thesis is to (1) review sexual selection theory with an emphasis on sensory communication, and (2) test whether olfactory communication is sexually selected in strepsirrhines. I examined the relationships between primate mating systems and several measures of olfactory communication in 22 species: scent marking rates, the number of scent marking methods, and the volume of the main and accessory olfactory bulbs. I also evaluated qualitative data on olfactory communication in three lemur species to determine whether they meet the criteria of a sexually selected trait. Polygynandrous and monogamous species did not significantly differ from each other in scent marking rates, scent glands, or volume of the main and accessory olfactory bulbs. Three species of strepsirrhine met all criteria of having sexually selected olfactory traits, suggesting that polygynandrous lemurs are subject to sexual selection on several levels of olfactory communication. / text

Odors that are essential to the survival and reproduction of a species take the form of complex mixtures of volatiles. Often, an odor source such as food or a potential mate releases a mixture with characteristic ratios between the components. Here, the encoding of the characteristic ratio between components of the pheromone released by a female moth is investigated in the antennal lobe (AL) of a male moth (Manduca sexta). The mechanisms by which olfactory systems of diverse insect species process odors are adapted to the particular environment and olfactory behavior of the animal. In the moth, innately attractive odors produce patterns of synchrony in the output of the AL, the projection neurons (PNs). Male moths exhibited attraction to synthetic mixtures of pheromone components that was selective for ratios at or near the natural ratio released by females. Selectivity increased as the moth neared the odor source and initiated mating behaviors. PNs in the macroglomerular complex (MGC) did not exhibit an effect of component ratio on their firing rate responses. However, pairs of PNs exhibited increased synchrony in response to the behaviorally effective ratios of pheromone components. Individual pairs exhibited selectivity for ratios within 1 order of magnitude from the natural ratio. Synchrony in PN spiking was not phase-locked to the network oscillations in the AL. A model for ratio-selective enhancement of synchronous PN output in the AL is proposed.

No description available.

The olfactory system has the remarkable capacity for neurogenesis following injury. However, the molecular mechanisms important for reinnervation of the olfactory bulb (OB) remain unknown. The matrix metalloproteinases (MMPs) are important components in many central nervous system (CNS) injury paradigms, yet remain unexplored in olfactory injury and recovery. To address the role of MMPs, the temporal expressions of MMP-9 and MMP-2 were examined in 3 olfactory injury models: nerve transection (NTx), methyl bromide gas (MeBr) exposure, and nerve transection with Teflon barrier (NTx-TB). Each injury model represents a different degree of olfactory injury and neuronal recovery. In NTx, sensory axons are lesioned, leading to neuronal degeneration and subsequent reinnervation of the OB. MeBr exposure damages the cell bodies of sensory neurons in the peripheral olfactory epithelium (OE), leading to degeneration and reinnervation of the OB without direct trauma to the OB. In NTx-TB, sensory axons are lesioned and a barrier is inserted following injury that blocks regenerated neurons from reinnervation of the OB. Following NTx, MMP-9 increased immediately in the OB and was localized to neutrophils, an inflammatory leukocyte. The elevated levels of MMP-9 corresponded to neuronal degeneration. To confirm this relationship, MMP-9 expression was measured following MeBr injury. MMP-9 increased during neuronal degeneration in the OB and was localized to neutrophils in the area of sensory axon degradation. These experiments demonstrated that MMP-9 is important for both neuronal degeneration and the acute inflammatory response following olfactory injury. In NTx injury, MMP-2 expression peaked at day 7 and corresponded to the transition between degeneration and reinnervation of the OB. MMP-2 was localized to the granule cell and external plexiform layers in control and day 7 bulbs. Following NTx-TB, MMP-2 remained low and was not expressed by regenerated axons. The absence of a MMP-2 peak in the NTx-TB injury suggests that this peak depends on reinnervation of the OB. This study demonstrates a temporal correlation between MMP-9 and degeneration and MMP-2 and reinnervation following olfactory injury. These findings provide new insight into the molecular mechanisms underlying olfactory nerve injury. Modulation of MMPs could provide novel therapeutic interventions to improve neuronal recovery following injury.

The Drosophila larva is a suitable model to study olfaction due to its numerical simplicity. The peripheral olfactory system consists of just 21 pairs of olfactory sensory neurons (OSNs), each expressing one, or at most two classes of olfactory receptors (ORs) that define the receptive range of the OSN. Larvae produce robust behaviours to many odours and are easily genetically manipulated. Unlike audition, relatively little is known regarding olfaction due to its complex nature - most odours exist as multimolecular units that vary in their identity and structure, concentrations and proportions. Until recently, most olfactory research has focused on the processing of simple odours, which does not realistically model real-world odours. Presented here is one of the first in situ investigations of odour mixture processing in the Drosophila melanogaster larva. Processing of odour mixtures was explored using both electrophysiological recordings of the peripheral olfactory system and behavioural assays at the output of the system, and the effects of various factors on responses were also explored. w1118 larvae in which all OSNs were functional, and larvae with only a single class of OSN (using the Gal4-UAS expression system) were studied. At the peripheral level, mixture responses were never entirely transformed from the components, and were always as large as or greater than the response to the strongest component, and therefore the neuron was either 'seeing' just one or more than one of the components, respectively. Mixture responses across all OSNs were always additive, hypoadditive or partially suppressive, and there were no instances of synergistic or fully suppressive responses. Peripheral mixture responses were both OR- and component-dependent, as the same mixture was represented differently across OSNs. At the behavioural level, mixture responses were mostly additive, partially and fully suppressive and therefore not always predictable from the components. Interestingly, responses of larvae with only a single class of OSN were mostly predictable as there was no complexity of processing arising from the combinatorial code. When all OSNs were functional and the combinatorial code appropriately activated, mixture responses were more complex and unpredictable. Associative conditioning experiments revealed that larvae were unable to identify components from within a mixture, providing evidence that, at least at the behavioural level, mixture responses were probably synthetic, and therefore likely that interactions between the components occurred at some point along the processing pathway. Mixtures were often dominated by the component inducing the largest firing rate, and carbon chain length and vapour pressure influenced, to some degree, which component dominated. The nature of mixture responses were affected by concentration which is consistent with a model of receptor competition - at low concentrations mixture responses were additive, whilst at high concentrations responses were reduced compared to an additive response. In contrast, prior experience had little effect on peripheral responses to pure odours and mixtures, although rapid adaptation was observed during exposure. Exposure did have an effect on subsequent behavioural responses to pure odours and mixtures, providing evidence of central effects of adaptation. The data presented here provides evidence that mixture processing is extremely complex, with many factors influencing and affecting the way that the system responds to mixtures. This data reveals an unexpected complexity in a numerically simple system and with such'simple' complex odours, and indicates the likelihood of more complex responses when all OSNs are functional.

The purpose of this study was to measure the influence of an ambient peppermint aroma on participants' time-on-task and performance while using FACTOR, an open-source e-Learning application. I proposed time-on-task was moderating between olfactory stimulation and performance. A 2x2 research design measured interaction of group (nonscented, scented) and gender of participants (N = 65). The learning content consisted of 28 African countries. Two methods for measuring time-on-task were employed: participant self-report at six learning intervals, and second, video recordings captured by, and stored on each participant's computer. Independent samples t tests were used to measure group and gender differences in time-on-task and performance. Relationships between time-on-task and performance were assessed using bivariate correlation and were reported as r values. Time-on-task differences between groups were not significant but garnered ES =.53. After 24 minutes of learning time, control females spent more time-on-task than control males (ES =.71), which was a statistically significant result. There was a weak to almost neutral correlation between time-on-task of all participants and performance (r =.1) where controls showed a weaker relationship (r =.05) than treatments (r =.26). The correlation between observed time-on-task and posttest performance was neutral for controls (r = .008) but moderate for treatments (r =.38). During the 40-minute learning session, the relationship between observed time-on-task and performance was r =.04 (females) and r =.55 (males), which was statistically significant. When examining time-on-task at the six measured intervals, the relationship with performance was strongest for treatments after 16 (r =.39) and 24 (r =.39) minutes of learning time. The direct influence of olfactory stimulation on performance was weak as the peppermint scent had a greater influence on time-on-task. Significant differences and notable effect sizes were not achieved by examining these variables. Analysis of the entire model showed the variables (condition, time-on-task, performance) were weakly correlated (r =.19) and that only 4% of the variance in the model was explained by its variables. As such, I failed to reject the null hypothesis, which was that time-on-task did not act as a moderator between condition and performance.

The work in progress, Pick Up Styx, investigates re-sensing and extra-sensing of the world. It is an exploration of communications with reference to quantum theory which challenges current sense perceptions, while engaging and exploring the notion of communications as signals. The methodology is a winding, coiling motion between research and creative practice based on the way my grandmother used to wind wool from a skein into a ball. The project investigates the game as a tool to examine the ciphers of perfumes that have been designed for love and happiness since 2001. The project aims to develop aesthetic pleasure in game play beyond the industry focus on games technology. Picking up the sticks and experiencing the perfumes in them is procedural to encountering the War on Terror, and the perfumes that have accompanied its progression over the last 8 years. In a materialist culture where technologies are enabling psycho kinesis, via the transmission of information signals, and where thought can influence matter in a variety of ways, we are training ourselves out of separatist thinking and fixation on the Western scientific paradigm. This project has grown from my curiosity regarding anomalous forms of cognition and paranormal perception, motivated by the need to address current issues of human relationship and environmental concerns.

Our senses take in a large amount of information, information that sometimes is congruent across sensory modalities. Crossmodal correspondences are the study of how this information across modalities is integrated by the brain, across which dimensions the correspondences exists, and how it affect us. In the present paper four experiments were conducted, in which potential crossmodal correspondences between audition, vision and olfaction were investigated. It was hypothesized that crossmodal correspondences between olfaction, vision and audition exist along different dimensions. The results showed significant correlations between olfaction and audition when volume varies, i.e., a high volume is associated to a high concentration of an odor, and a low volume is associated to a low concentration of an odor, and vice versa. Furthermore, existing correspondences between vision and audition is reconfirmed. In conclusion, the results provide support to the notion that crossmodal correspondences exists between all sensory modalities, although along different dimensions.

Drosophila is a simple and genetically tractable model system for studying neural circuits. This dissertation consists of two studies, with the broad goal of understanding sensory processing in neural circuits using Drosophila as a model system.

Monarch butterflies (Danaus plexippus) are well known to depend almost exclusively on milkweed (genus Asclepias) host plants for oviposition sites, as their larvae need to ingest compounds critical for adult butterfly chemical defense against predators. Many phytophagous insects make fast and accurate decisions on the quality of host plants, and whether or not to accept them as oviposition sites. We were interested in the cues that attract monarchs (males and females) to milkweed, while in flight, before contact stimulation can occur. We developed a novel flight apparatus to test monarch attraction behaviour, under a number of different experimental protocols, to both milkweed and control stimuli in order to identify the cues necessary or sufficient for monarch attraction to milkweed. Monarchs were found to be attracted to milkweed stimuli when the visual image alone of milkweed was available or when olfactory cues alone were available. Attraction behaviour was maximized when both cues were available. It was also discovered that attraction to milkweed was significantly diminished when ultraviolet reflection from milkweed leaves was prevented from being detected by monarchs in flight. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2007-08-09 12:22:17.691