![]() ![]() You can play the tone and they will continue about their business as if they have no bad memories associated with the noise. If you attempt this experiment in mice with lesions to the amygdalae, however, they display an impaired ability to "remember" that the tone preceded the foot shock. Thus, they will display a fear reaction (e.g., freezing in place) as soon as the tone is played, but before the shock is initiated. For example, if you take mice with intact amygdalae and play a tone right before you give them an uncomfortable foot shock, they will very quickly begin to associate the tone with the unpleasant shock. In addition to its involvement in the initiation of a fear response, the amygdala also seems to be very important in forming memories that are associated with fear-inducing events. ![]() Watch this 2-Minute Neuroscience video to learn more about the amygdala. The direct pathway from the thalamus to the amygdala may be one way to achieve this type of response. Instead, you want your body to experience immediate fear and jump backward without having to consciously initiate this action. For example, if you are walking through the grass and a snake darts out at you, you don't want to have to spend a lot of time cognitively assessing the danger the snake might pose. This type of reflexive response can be useful if we really are in great danger. This allows for the initiation of a fear reaction before we even have time to think about what it is that’s so frightening. There is a pathway that runs from the thalamus to the amygdala, and sensory information about fearful stimuli may be sent along this pathway to the amygdala before it is consciously processed by the cerebral cortex. Interestingly, research suggests that information about potentially frightening things in the environment can reach the amygdala before we are even consciously aware that there’s anything to be afraid of. When we are exposed to a fearful stimulus, information about that stimulus is immediately sent to the amygdala, which can then send signals to areas of the brain like the hypothalamus to trigger a " fight-or-flight" response (e.g., increased heart rate and respiration to prepare for action). ![]() Since, the amygdala has become best known for its role in fear processing. ![]() The constellation of behavior that resulted from amygdalae removal was called Kluver-Bucy syndrome, and it led to the amygdala being investigated for its role in fear. Among other things, the monkeys became more docile and seemed to display little fear. Our modern understanding of amygdala function can be traced back to the 1930s, when Heinrich Kluver and Paul Bucy removed the amygdalae of rhesus monkeys and saw drastic effects on behavior. It is best known for its role in the processing of fear, although as we’ll see, this is an oversimplified perspective on amygdala function. The amygdala is recognized as a component of a group of brain structures referred to collectively as the limbic system, and is thought to play important roles in emotion and behavior. What is the amygdala and what does it do? Although we often refer to it in the singular, there are two amygdalae-one in each cerebral hemisphere. The term amygdala comes from Latin and translates to "almond," because one of the most prominent nuclei of the amygdala has an almond-like shape. The amygdala is a collection of nuclei found deep within the temporal lobe. ![]()
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