Hamm, JPKirk, IJKung, Eva2016-08-0820162016https://hdl.handle.net/2292/29848Long-term potentiation (LTP) is the synaptic mechanism that underlies learning and memory formation. LTP has been extensively explored by studies that was conducted on animals. Furthermore, LTP has been studied in human cortical tissue obtained from patients prior to going into surgery. However, due to the invasiveness of this method, the study of LTP in humans has not been explored in as much depth as it has in animals. Recently however, an increasing number of studies have shown that LTP-like effects can be induced using high-frequency sensory stimulation in humans. Thus, there is considerable potential for sensory stimulation to be used as a non-invasive alternative to induce and measure LTP in humans (hLTP). The effect reported from the studies that utilized this method so far has strongly implied this effect is analogous to the LTP as found in animals and human cortical tissue. Comparatively, this method of examination is still relatively new. This calls for further experiments to be conducted to extend the understanding of this paradigm and the effect documented using these protocols. The non-invasive hLTP paradigm has the potential, not only to explore LTP in healthy human participants, but to further the understanding of learning and memory formation. While the literature at present suggest this effect to be localised to the cortical region, this has yet to be clearly determined. Therefore, one of the two key aims of this thesis was to examine where visual hLTP is occurring in the brain using the non-invasive paradigm. Results from this set of experiments strongly indicated hLTP to be occurring in the visual cortical region. Furthermore, while the study of stress hormones in relation to memory performance has received substantial amount of attention, adrenal steroids influence on LTP has been less explored in healthy human participants. The non-invasive technique appears to be highly promising as a method to examine LTP in healthy human participants. Therefore, the second key aim of this thesis was to investigate the influence of cortisol on hLTP. The results gave some indication that less stress is correlated with better learning and memory formation. The potential of the rapid sensory stimulation paradigm is just being uncovered. Furthermore, this paradigm could be highly useful if applied to neurocognitive disorders in the clinical settings. A discussion of this is presented at the end of this thesis.Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htmhttps://creativecommons.org/licenses/by-nc-sa/3.0/nz/ThesisCopyright: The Authorhttp://purl.org/eprint/accessRights/OpenAccessQ112931173