Anteroventral thalamic nucleus: lesion effects on memory and cortico-limbic electrophysiology
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
Damage to the anterior thalamic nuclei (ATN) is associated with severe memory impairment in humans. What is unclear is how this damage affects electrophysiological activity within an extended hippocampal circuit for memory, of which the ATN is a key component. The current study provides a novel comparison of the electrophysiological activity of rats with lesions to the ATN and intact rats using two electrophysiological measures. These measure are peak power generated by each structure of interest, and the amount of signal amplitude covariance shared by structures, known as coherence. Data were recorded from four key neural memory structures (prefrontal cortex, hippocampus, retrosplenial cortex, and subiculum) during a behavioural paradigm in which rats were presented with novel or previously visited (repeat) arms in a radial arm maze. The current study found decreases in peak power within the sham group when entering repeat arms verses novel. There was also significantly reduced power in rats with ATN lesions compared to shams in the right hippocampus when entering novel arms, and in the right hippocampus and subiculum when entering repeat arms. While there were no significant between group differences in coherence, there was a reduction in coherence in shams when entering novel verses repeat arms in all structures analysed. Overall findings suggest that an intact ATN may play a regulatory role in electrophysiological activity across the extended hippocampal memory system.