Exploring the Human Condition

The amygdala is an almond shaped structure located deep within the brain's medial temporal lobe. It is part of the limbic system and is thought to control our basest emotions, such as aggression, fear and arousal.

The amygdala is especially important for learning during classical conditioning when stimulus paired with the response is painful. For example, rats that have a shock paired with the presence of light have a larger startle response to a loud noise that is presented directly after a light is turned on. This is because the amygdala has learned that light is associated with pain, so while waiting for the shock, the rat is more aroused and has a larger startle response, a natural reaction, to a loud noise. In other words, the amygdala is important for learning what to fear.

Studies with fMRI scans have also supported this theory, as the amygdala shows lots of activity in response to fear and aggression, but not nearly so much as with sadness and happiness. When concerning fearful and angry expressions, the amygdala shows the most activation when shown a fearful face directed towards the viewer, and an angry face directed away from the viewer. Scientists believe that this is because of the confusion involved with these emotions. We expect someone to be fearful of their surrounding, but when that fear is directed at us, it is something we don't understand unless put in a situation where we are trying to be frightening. It's similar with the angry face as well. Anger is something that we sometimes expect to be directed at us, but when directed away from us, it's more confusing and we desire to know what's causing the anger.

Damage to the amygdala manifests itself in a "fearless" type of disposition. An individual with amygdala damage may report being afraid of snakes, but when confronted with one, they treat it like a domestic pet, even if venomous. In other words, they do not actually feel or experience the emotion of fear. However, another interesting discovery was made by examining amygdala damage was it's role in recognizing fear. A normal human will focus on the eyes when asked to identify a person's emotion. A person with amygdala damage will focus on the nose and mouth, and especially have problems identifying the emotions of fear and disgust. When asked to draw emotions, they are usually able to capture most emotional cues, even if they can't identify them on a face, but when asked to draw fear, they are at a loss and cannot think of how to portray it on paper.

Hi! I have an MS in Applied Research and a BA in Psychology. I'm a genuinely huge Psychology fan and I love seeing blogs like this one who share the same passion. I'm also a musician on the side and I just released my second album titled, "Ego Depletion." It's an instrumental electronic album loosely inspired by concepts of Jung, Flow, and the destruction of self-control. Give it a listen and see what you think - I'm sure other Psych fans might be into it too. Thanks! 

The brainstem is one of the oldest parts of the brainstem and is considered one of the "simplest" parts of the brain because creatures that are evolutionary older than humans possess brainstems that look like ours and also function like ours do. The brainstem controls basic autonomic actions (actions that don't require conscious thought) that are essential for our survival like breathing, heart rate, blood pressure, digestion, alertness and arousal. Located at the juncture of the spinal chord and the cerebrum, it serves as a connections between the spinal chord and the rest of the brain, controlling the motor signals that travel between them. The brainstem is not a single brain structure, but also consists of the midbrain, the pons and the medulla.

The midbrain is located at the front of the brainstem and is involved in vision, hearing, and eye movement. Located in the back of the midbrain, a bundle of axons connect the cerebral cortex and are extremely important for voluntary motor functions. 

The pons are involved in motor control and sensory analysis and are loacated towards the back of the brainstem. When the brain receives a sensory input, it travels through the pons before being redirected to the proper part of the cerebellum. They also are involved in functions such as posture, balance and sleep.

I've already outlined the brain systems that I learned from my psychology classes, but I'd also like to describe another popular way to outline the brain. This also breaks the brain down into three basic systems: the hindbrain, midbrain and forebrain. 

The Hindbrain: This is the "oldest" part of the brain evolutionary wise, and is located at the top of your spinal chord. This system controls some of our most basic functions such as breathing, digestion, muscle coordination, and maintaining balance. Structures in this brain system include (but are not limited to)

The medulla oblongata

The pons

The cerebellum

The Midbrain: Between the midbrain and the hindbrain, the brainstem is created, which is in control of all the basic survival functions mentioned above. While the hindbrain deals largely with controlling physical survival mechanisms, the midbrain specializes in understanding sensory input from the five basic senses. It also helps to register arousal. By arousal, I do not necessarily mean sexual arousal, but more of an awareness and alertness. The midbrain also serves to connect the hindbrain to the forebrain. Basic midbrain structures include:

The reticular formation

The Forebrain: This part of the brain contains most all of the higher brain functions that are the most recently evolved. These include fine motor functioning and thought processing, raw emotion necessary to survival (fear, aggression, jealousy, arousal), complex emotion, as well as relaying sensory information to other parts of the brain. The forebrain structures include:

The cerebrum and cerebral cortex (which includes the frontal, temporal, occipital, and parietal lobes of the brain)

The hypothalamus

The hippocampus

The amygdala

The thalamus

This is just a basic run down of the hindbrain, midbrain and forebrain organizational structure. As you can see, most of the basic brain structures are still accounted for in this outline, but it groups the entire limbic system and cerebrum to the same area of the brain. Other versions of this outline will divide the brain into more areas within the basic division, but I wanted to try and use terms found in my previous outline. I'm not as comfortable with this method of division, but I hope you enjoyed this alternate division system.