Can Medial Septal Stimulation that Elicits Hippocampal Theta Rhythm Repair Cognitive and Emotional Deficits Resulting from Vestibular Lesions?
Bilateral vestibular lesions cause atrophy of the hippocampus and subsequent deficits in spatial memory and the processing of emotional stimuli. These problems are seen in both rats and humans. Vestibular lesions also impair hippocampal theta rhythm in rats. The aim of the present study was to investigate whether restoring theta rhythm to the hippocampus of a rat, via stimulation of the medial septum, would repair the deficits caused by vestibular lesions. It was hypothesised that the restoration of theta would repair the deficits and the vestibular rats would exhibit behaviour and EEG similar to that of the sham rats. Rats were given either sham or bilateral vestibular lesions followed in a later operation by electrode implants. Half of the lesioned rats received stimulation. Subjects were tested in spin, openfield, elevated T-maze and forced alternation tests. Except for the spin test which measured the natural production of theta, each test measured either cognitive or emotional functioning. BVD caused a deficit in hippocampal theta rhythm. Stimulation restored theta in the vestibular rats however the stimulation did not repair the cognitive and emotional deficits caused by the lesions. It was concluded that stimulation, at least in the form used here, would not be a viable treatment option for vestibular damaged humans. Further investigation is needed to determine if there is a true difference in the effects of vestibular lesions between rats and humans. The unique ability of humans to worry about future events and the role this has in the severity of symptoms experienced was another issue that could have contributed to the difference between the expected and observed findings.
Advisor: McNaughton, Neil
Degree Name: Master of Science
Degree Discipline: Psychology
Publisher: University of Otago
Keywords: Vestibular; Hippocampal theta
Research Type: Thesis