Kurzfassung

In the first funding period of the research unit, we devised and established novel behavioural paradigms to shed light on the neural mechanisms governing extinction learning and its dependence on contextual cues in appetitive settings. These studies have demonstrated involvement of both the hippocampus and the nidopallium caudolaterale (NCL, the avian analogue of mammalian prefrontal cortex) in extinction learning. Specifically, inactivation of these structures results in very similar effects...In the first funding period of the research unit, we devised and established novel behavioural paradigms to shed light on the neural mechanisms governing extinction learning and its dependence on contextual cues in appetitive settings. These studies have demonstrated involvement of both the hippocampus and the nidopallium caudolaterale (NCL, the avian analogue of mammalian prefrontal cortex) in extinction learning. Specifically, inactivation of these structures results in very similar effects as in the corresponding mammalian structures: inactivation of NCL non-specifically suppresses conditioned responding and impairs extinction learning through a reduction in the number of response-outcome pairings. Inactivation of hippocampus on the other hand may impair the consolidation of extinction learning. Single-unit recordings of NCL neurons during task performance revealed that firing rates during CS presentation differ markedly across acquisition and extinction of the operant response, reflecting the changing valuation of the CS during the course of the experimental session.
In the second funding period, we aim to extend the scope of the project both in terms of brain structures to be investigated as well as in the choice of methods. We will characterize the involvement of a) the avian amygdala and b) the nidopallium frontolaterale (NFL), a visual associative area. While the amygdala has traditionally been studied in Pavlovian fear conditioning, recent studies showed that amygdala neurons are well responsive to appetitive stimuli. These studies have dramatically altered the prevailing view of the amygdala as a hub for fear learning and extended its role to a brain area involved in updating the valuation of exteroceptive stimuli, be they of positive or negative value to the organism. The NFL, on the other hand, is a higher-order visual brain area; accordingly, we expect the NFL to be involved in visual-associative learning and thus to contain a representation of the conditioned stimuli.
While single-neuron recordings and pharmacological techniques are powerful tools to examine neural correlates of cognitive processes, they only provide a restricted view on the network mechanisms of behaviour. To achieve a more complete picture of the brain networks underlying extinction learning, we aim to extend our methods repertoire to functional magnetic resonance imaging of the pigeon brain during the extinction of a conditioned response. Once accomplished, an array of diverse and powerful methods spanning combinations of behaviour, electrophysiology, pharmacology, and imaging will for the first time become available in a single model organism – the pigeon.» weiterlesen» einklappen