Final answer:
The amygdala, part of the limbic system in the brain, is the structure heavily involved in the learning of fear responses due to its role in processing emotions and attaching emotional significance to memories.
Step-by-step explanation:
The amygdala is heavily involved in the learning of fear responses. This is because the amygdala, which is a group of nuclei located in the medial temporal lobe, is part of the limbic system. The limbic system regulates emotion, and the amygdala in particular plays a crucial role in processing emotional reactions such as fear and anxiety. Research has shown that the amygdala is responsible for attaching emotional value to memories during the process of memory consolidation; it helps encode memories more deeply when the event is emotionally significant.
Experimental work has also demonstrated the critical role of the amygdala in fear conditioning. Through the use of classical conditioning, where an initially neutral stimulus becomes associated with a fear response, the importance of the amygdala becomes evident. For instance, when neurons in the lateral amygdala of rats were destroyed, the fear response associated with a previously neutral tone diminished. Moreover, the amygdala has connections to sensory areas of the brain and is involved in attaching emotional value to learning processes, demonstrating its integral role in the formation of fear memories.
Therefore, the final answer to the question that the amygdala is heavily involved in the learning of fear responses is substantiated by various studies and experiments.