Is there an emotional brain? Pt.1(intro)

Is there an emotional brain? As much as we like simplicity in models of science, and the locationist view makes things easier for us to understand, research points to the answer that emotions are not localized to one specific brain region or circuit. 

The limbic system hypothesis was put forth by Paul MacLean in the 1950s (although some theories led up to this prior such as the Papez circuit). It divides the more deeply fundamental structures with those that are thought to have developed further on in evolution, in ‘higher’ mammals. The limbic system is one component of the triune brain theory that divides the brain up into the neocortex, mammalian brain and reptilian brain. The reptilian brain is proposed to be in charge of responses for survival such as breathing and heart rate. The reptilian brain is called so due to its structures being found also in reptiles.

The limbic system is thought to have developed later in evolution and is commonly thought to be the mammalian brain. The system involves many structures such as the amygdala, hypothalamus and the hippocampus. Due to this, the limbic system is often thought of as the ‘emotional brain’.

The neocortex is the last layer of the brain, involved in higher order cognitive processes hence often being called the ‘human brain’. This is the reason that humans are able to develop culture and communicate using languages and other processes unique to humans.

Although this theory of an emotional brain being located in the limbic system has some valid points, there is much debate about how much of this is true. Some scientists believe that this locationist view assumes that every emotion category follows this same exact pathway which is not the case.

The regions that the limbic system is composed of is still not universally agreed upon.

For example, the Papez circuit of the limbic system consists of the below:

hippocampus àfornix à mamillary bodyà anterior nucleus of the thalamus, àcingulum à the corpus callosum àentorhinal cortexàhippocampus

Whereas, MacLean proposes that the amygdala, some areas of the prefrontal cortex and the cingulate cortex are also involved in this circuit.

(to be continued…)

1.     Briefly describe the limbic system hypothesis and its historical role in the cognitive neuroscience of emotion. Explain which aspects of the hypothesis have been questioned and which remain valid.