Emotion as Memory

The more emotions are analyzed from a biological perspective, the more apparent it is that emotion is not a separate subsystem of the mind, but a pervasive feature of it. It has a specific evolutionary function and a crucial role in our daily actions.

Emotions are key to learning and behavior, because fear conditioning imprints emotional memories that are quite permanent. The relationship between emotion and memory goes beyond fear, but fear is the emotion that has been studied more extensively. As a matter of fact, fear seems to be a common ground for (at least) all vertebrates. The effects of fear on memory are powerful. John Aggleton has offered a model of how memories about fearful experiences are created in the brain by interactions among the amygdala, the thalamus and the cortex.

Emotional memory (stored in the amygdala) differs from declarative memory (which is mediated by the hippocampus and the cortex). Emotional memory is primitive, in the sense that only contains simple links between cues and responses. A noise in the middle of the night is enough to create a state of anxiety, without necessarily bringing back to mind full consciousness of what the origin of that noise can be. This actually increases the efficiency (at least the speed) of the emotional response.

Emotional and declarative memories are stored and retrieved in parallel. Adults cannot recall childhood traumas because in children the hippocampus has not yet matured to the point of forming conscious memories, but the emotional memory is there.

Emotions are the brain's interpretation of reactions to changes in the world. Emotional memories involving fear can never be erased The prefrontal cortex, amygdala and right cerebral cortex form a system for reasoning that gives rise to emotions and feelings. The prefrontal cortex and the amygdala process a visual stimulus by comparing it with previous experience and generate a response that is transmitted both to the body and to the back of the brain.

Darwinian emotions?

The amygdala has been recognized as a major center for the creation of emotions. For example, animals whose amygdala was removed showed no emotions. It turns out, though, that the neurons of the amygdala are continuously generating what appear to be emotional states, just like the heart beats all the time. This goes against our belief that emotions are due to our reaction to external stimuli. Instead we seem to be producing emotions all the time, regardless of the external stimuli.

Whenever modern Science finds itself in this situation, Darwin's specter arises: are emotions just like antibodies, neurons and thoughts? Are they produced randomly all the time and then the environment (the situation) "selects" which ones have to survive?

The Complexity of Emotions

Two mysteries remain. The first one is relative to consciousness: why do I also have to "feel" the emotion? Couldn't the brain just send a signal to the organs without bothering me? Why am I aware of it? A possibility is that being aware of an emotion means that the self can preempt the mechanic activation of a response in cases in which it would be counterproductive. Sometimes fear or hunger can lead us to actions that we may regret. If we were not aware of our emotions, we would not be able to stop the consequent actions.

The second mystery is how did we to come to build such complex feelings as, say, love. Love for a child is relatively easy to explain. But love for a woman is often a rather contorted and turbulent affair. Most of the emotions we feel during a day would be hard to be categorized as simple "fear" or "love" or "pain". They seem to be grounded on such simple, primitive emotions, but then they exhibit a degree of complexity above that. Are they "evolutionary" consequences of primitive emotions (just like a human brain is the evolutionary consequence of very primitive nervous systems), which are now part of our genetic program, or are they "social" consequences of interaction with other emotional beings: are they innate or acquired? How is a complex emotion formed from more elementary emotions?

And, again, one more "why": what is the advantage of building more and more complex emotions? Could it be that more complex emotions express a better balance of reason and instinct?