It is essential for the brain to keep track of self-movement in order to establish a stable percept of the environment. The major source of information about self-movement is vision. However, non visual (extraretinal) information can also contribute to the sense of motion. This thesis investigated the role of extraretinal signals to account for self-generated motion in the case of eye movements. The interaction of two types of eye movements, i.e. smooth pursuit and saccades, was used to investigate the system's capacity to keep track of self-motion. This work focused in particular on the ability of the saccadic system to account for smooth pursuit eye movements in darkness. A detailed analysis of the saccade metrics allowed the identification of a novel neural mechanism for smooth eye movement integration. As a result, the saccadic system could compensate for smooth eye displacements and thus was able to ensure space constancy across different eye movements. In addition to the experimental approach of this thesis, a mathematical model was developed that described all current findings.

It is essential for the brain to keep track of self-movement in order to establish a stable percept of the environment. The major source of information about self-movement is vision. However, non visual (extraretinal) information can also contribute to the sense of motion. This thesis investigated the role of extraretinal signals to account for self-generated motion in the case of eye movements. The interaction of two types of eye movements, i.e. smooth pursuit and saccades, was used to investigate the system's capacity to keep track of self-motion. This work focused in particular on the ability of the saccadic system to account for smooth pursuit eye movements in darkness. A detailed analysis of the saccade metrics allowed the identification of a novel neural mechanism for smooth eye movement integration. As a result, the saccadic system could compensate for smooth eye displacements and thus was able to ensure space constancy across different eye movements. In addition to the experimental approach of this thesis, a mathematical model was developed that described all current findings.

This research explores the capacity for functional photoreception in larvae of the mountain pine beetle (Dendroctonus ponderosae), an extremely important forest pest insect that is well adapted for development beneath the bark of pine trees. Phototaxis tests, gene expression analysis and development experiments were integrated to assess mountain pine beetle larvae for light sensitivity. When presented with a phototaxis choice test, larvae preferred dark over light microhabitats, revealing that larvae sense and respond behaviourally to light. Long wavelength opsin transcription was identified in all life stages, including eggs and larvae, suggesting that D. ponderosae possesses extraretinal photosensitive capabilities across its life cycle. The long wavelength opsin could function in phototaxis or the development phenology of immature beetles, while the ultraviolet opsin, only found to be expressed in pupae and adults, is likely to function in dispersal via the compound eyes. Results from two development experiments reveal an effect of photoperiod treatment on beetle development rate when reared from the egg stage, but not when reared from mature larvae, indicating that a critical photosensitive life stage(s) must occur in D. ponderosae prior to the third larval instar. An effect of photoperiod on adult emergence rates, however, appears to be independent of larval rearing conditions. The discovery of opsin expression and negative phototaxis in eyeless mountain pine beetle larvae, in addition to an effect of photoperiod on immature development and adult emergence rates, suggest that light and photoperiodism likely function in survival and life cycle coordination in this species. / Graduate / 2018-10-17