From the bottom of my heart

Dr Claudia’s Answer:

Thanks very much for your insights, this is a great question.

First, what are emotions? I think this is one of those fundamental questions bridging philosophy and neuroscience, which makes it a fascinating topic even to this day. The psychologist William James first proposed that feelings are derived from sensing our body states over a century ago. And these ‘body states’ are mapped in the central nervous system (CNS), specifically in the upper brainstem and cerebral cortex. Basically, feelings are mental experiences of body states.

Emotions such as those you describe (anger, fear, sadness, joy, passionate love, etc.) are a set of innate physiological functions mostly triggered by the perception or recall of external stimuli (with some exceptions). On the other hand, drives are aimed at satisfying certain needs (hunger, thirst, libido, play, mate-attachment, etc.). Both drives and emotions can elicit feelings. And these feelings are represented in the nervous system, typically with a positive or negative valence - either it makes you feel good or bad.

More ‘recent’ brain structures - like the cortex - contribute to but are not essential for the emergence of feelings, which are likely to arise instead from older regions such as the brainstem, suggesting that feelings are not exclusive to humans or even mammals. Personally, I think we are only beginning to understand emotion and feelings in other animals and even plants!

Now why do you ‘feel’ in your body?

Although feelings involve a central process, they are rooted in events occurring at the cellular level, specifically in the superhighways of the nervous system that connect the body to the brain. In neuroscience, we are speaking of unmyelinated axons, or the long nerve highways that transmit signals slightly slower than myelinated structures. Myelin is the fatty sheath that surrounds most fast-acting nerves - think of this like the rubber coating on a bare wire. The rubber speeds up conductance and reduces resistance of the electricity flowing through the wire; the brain’s electrical wires work in a very similar fashion. It turns out that the processing of body signals largely relies on unmyelinated structures. For instance, the vagus nerve is the main conduit that carries carries signals pertaining to body (visceral) states - especially from the cardiovascular, respiratory, gastrointestinal and genitourinary systems - to the central nervous system. Think of it like your main body-brain connector. You know the term ‘gut feeling’? You can thank the vagus nerve for this sensation. Recent neuroscientific studies are shedding light on a fascinating new argument about altruism: that a branch of our nervous system, namely the vagus nerve, evolved to support such behavior.

So it seems that feelings paved the way for the establishment of higher levels of cognition and consciousness, culminating in the modern human mind.

For this answer, I’ve taken some neuroscientific research done by researchers far more experienced than I in this field. During my graduate studies I was lucky enough to have Dr. Antonio Damasio as one of my professors in our program. He’s written some interesting books on this topic for your further reference.