[MUSIC PLAYING] INSTRUCTOR: Welcome to this short video by Soton Brain Hub on the anatomy of the limbic system. So the limbic system is a group of brain structures found deep beneath the cerebral cortex and sits just above the brain stem. Its main function is involved in regulating many of our emotions and motivations, particularly those related to survival, such as fear, anger, hunger, and sexual behavior, but it is also involved in higher mental functions such as learning and memory. 

The limbic system is the reason that some physical things, such as eating, seem so pleasurable to us, and the reason why some medical conditions, such as high blood pressure, are caused by mental stress. Unfortunately, there is no consensus as to what structures constitute the whole of the limbic system, so in this video, we'll stick to those viewed as the most important. 

Firstly, if we have a look at the amygdala, which here we have colored in blue, the amygdala is a small, almond-shaped structure located deep and medially within both temporal lobes. This is often known as the emotional center of the brain, as it is responsible for fear conditioning or the associative learning process by which we learn to fear something. 

If we were to stimulate this area, we would induce emotions such as anger, violence, fear, and anxiety. On the other hand, if we were to damage both amygdalae, we would lose the ability to feel these emotions and become much more mellow and develop disinhibited behaviors. This is called Kluver-Bucy Syndrome. 

Now, the amygdala is in close proximity to the hippocampus, which here we have colored in purple. The hippocampus plays a key role in forming and storing new memories, in particular consolidating short term memories to long term memories. If we were to damage our hippocampi, we would develop a condition called anterograde amnesia, which is the inability to form new memories, although older memories, such as those from childhood, would still be safe. 

Now, the hippocampus sends c-shaped axonal projections through the forebrain, around the diencephalon, and into the hypothalamus via the fornix, which we have here colored in yellow. The hypothalamus, which is colored in green, is a small group of nuclei that have many different functions. For example, it plays a major role in regulating the endocrine system, in particular through its close connections to the pituitary gland via the infundibulum and the hypotheses portal system. 

It also regulates our autonomic nervous system, which includes functions like the fight and flight or rest and digest responses and body temperature. It is also involved in regulating our sleep wake cycle in response to light and many other vital activities. 

Just superior to the hypothalamus, we have the thalamus colored in red, which is a large mass of gray matter cells that constitute the main relay station in the brain, whereby sensory and motor signals are sent to and from the spinal cord and the cerebrum. This is important in the limbic system, as much of what we see, hear, and feel influences our emotions. 

Finally the thalamus has many connections to the cingulate gyrus, colored here in gray, which is located on the medial aspect of the brain just superior to the corpus callosum, and is separated by-- which is then separated by the colossal sulcus and bordered then superiorly by the cingulate sulcus. The cingulate gyrus helps regulate pain and emotion, but is particularly involved in driving the body's conscious response to unpleasant experiences, and therefore, the avoidance of negative consequences. 

So in summary, the limbic system comprises of a complex group of structures that are important in various functions, such as interpreting emotional responses, storing memories, and regulating bodily functions. That's our quick overview of the limbic system, so thanks for watching. 

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