Year: 2009
Type: dissertation
Abstract: Classical eyeblink conditioning is a model of associative learning in which a tone is repeatedly paired with an airpuff towards the eye to produce a learned response, ie. a blink in response to the tone alone. The neural basis of eyeblink conditioning is well-known: While the cerebellum is crucial at all times, the hippocampus is thought to participate mostly when the task is complex. However, hippocampal activity shows learning-related changes, and the spontaneous level of theta activity, a ~6 Hz oscillation dominating the hippocampal electrophysiological activity, predicts subsequent learning rate also when the task is simple. Then, how exactly, and why, does hippocampal theta activity relate to classical eyeblink conditioning? Three variants of the conditioning paradigm (delay, trace and discrimination-reversal) differing in complexity and hippocampal contribution were applied in rabbits, and extracellular electrical activity was recorded simultaneously. The neural state reflected by the level of hippocampal theta activity was found to affect specifically the rate and strength of association formation between the tone and the airpuff. In addition, the state reflected by the level of hippocampal theta activity changed according to the demands of the external environment mirroring the subjects' persistent yet adjustable tendency to respond to external stimuli. It was also shown that theta oscillations in the hippocampus and the cerebellum synchronize when the relative power of the hippocampal theta activity is high thus possibly mediating communication between these structures both involved in learning during eyeblink conditioning. In sum, the thesis shows how and why hippocampal theta activity relates to classical eyeblink conditioning.
Author: Miriam S. Nokia
Language: English
Topic: Memory and Neural Mechanisms
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2234973442