Hippocampus

The amygdala is a paired structure the resides in the temporal lobe of the brain below the uncus. There are about thirteen separate nuclei in the amygdala. Again, is sole function is to regulate the interactions between your emotions or behavior and to provide input int the memory centers of the brain.

The amygdala is the structure that first responds to fear. It has connections to the memory center of the brain, which is the amygdala and also to the prefrontal cortex, which largely regulates and tempers the amygdala response to fear.

There are two outgoing pathways in the amygdala. These include the dorsal pathway that projects to the septum and hypothalamus of the brain and the ventral route that travels to medial dorsal thalamus and the hypothalamus as well. There are also connections to the basal ganglia, the ventral pallidum, and ventral striatum. All of these relays are necessary to identify safety, the intentions of others, and the ability to use neuroception to get a sense of the safety of the situation in subconscious ways.

Anxiety, fear, aggression, emotionally-charged memories, and social thinking are all related somewhere to the amygdala. If the amygdala is stimulated, the perception will be one of fear. It send of these fear signals to the hippocampus where memories are affected and send signals or receive signals from the prefrontal cortex, which can modulate fear. There are specific parts of the amygdala like the dorsal amygdala that regulates physiological responses to stress; the central amygdala addresses fearful stimuli, and the extended amygdala is involved in the perceptions of stress and anxiety.

HIPPOCAMPUS

The hippocampus is the main memory structure of the limbic system, where it is located deep within the brain. It is heavily involved in the consolidation of memory and on decision-making skills. It is a collection of gray matter material located in the hippocampal gyrus near the lateral ventricle so that it forms part of the medial surface of the temporal lobe. There are three separate zones: the hippocampus proper, the dentate zone, and the subiculum. Figure 16 shows where the hippocampus is located:

Figure 16.

We will talk more about memory in the next few chapters but the basics of the acquisition of memory is the registration or memory, the storage of memory, and the retrieval of memory at a later time. Parts of the hippocampus are important in memory processing in all of these areas. Impairments can happen in short-term memory and long-term memory. Because the hippocampus is linked as part of the limbic system, its activity is highly regulated by one’s emotional state. It can take on memories related to the basic senses as well.