How our body represents itself in the brain

If someone asked you whether your hand belongs to you, you would probably answer naturally, “Yes.”
However, from a neuroscience perspective, the question is more complex: how do you know that this hand is truly yours? How do you know you even have a body? What makes you feel that it belongs to you, that it’s part of you? How can you tell where it begins and where it ends? How do you constantly keep track of its position in space?

A simple exercise to feel your own body

Try this brief exercise: imagine a straight line running down the center of your body, dividing it into two halves — left and right.
Now, using your right hand, gently press different parts of the right side of your body:

• Cheek

• Shoulder

• Ear

• Thigh

• Knee

You can recognize these parts because each one is faithfully represented in a two-dimensional neural map located in the left hemisphere of your brain — the area specialized in touch. The same is true for the opposite side: each “part” of your body is mirrored in a corresponding area of the right hemisphere.

Our brain maintains a detailed map of the entire surface of our body, with specific representations for every finger, hand, cheek, lip, eyebrow, shoulder, hip, and knee.

The concept of the body map

A map is essentially a diagram that establishes a direct correspondence between two different entities.
Like a road map, where each point corresponds to a real-world location and adjacent points represent nearby places, the same happens with the body maps in our brain.

The external environment and the anatomy of our body are precisely mapped onto brain tissue. The spatial relationships of our body’s surface are preserved in the somatosensory map: the map of the foot lies next to the shin, which is next to the thigh, and so on.

Whenever someone pats you on the shoulder, the nerve cells in that region of the map light up. When you put on a shoe, the corresponding part of your foot map is activated. And when you scratch your elbow, both the elbow and fingertip regions become active.

These maps are our physical window to the world, the channels through which raw tactile information flows into the brain.

Pathways of sensory information

Tactile information is collected by specialized receptors all over the body and transmitted through the spinal cord to the brain via two main pathways.

The older pathway, in evolutionary terms, carries information about pain, temperature, itch, tickle, sexual sensation, and crude touch (such as feeling that you’ve been struck on the knee but not distinguishing between a bean and a pebble). It also carries affective touch — gentle caresses that were essential to developing our body map as infants.

The newer pathway conveys fine touch — the precision required to thread a needle or turn a page — as well as information from receptors in our joints, bones, and muscles, allowing us to perceive position and movement.

When these sensory signals reach the brain, they combine to create complex sensations like moisture, softness, elasticity, or roughness. The same happens with pain: a blend of tactile and nociceptive signals allows us to experience a rich variety of unpleasant sensations — the sting of a sunburn, the sharp pain of carpal tunnel syndrome, or the itch of a healing scar.

The motor map

We also have a primary motor map, which allows us to perform movements. Unlike the sensory map, it doesn’t receive input from the skin — it sends output signals to the muscles.

Located in both hemispheres, this motor map is essential for coordinating fine motor skills and maintaining complex postures in space — dancing, swimming, running, doing yoga, or playing a musical instrument.

When we move our toes, the corresponding regions of the motor map activate. When we stick out our tongue, the areas controlling the tongue and jaw light up as well.

Thanks to this map, much of our movement coordination happens effortlessly and unconsciously.

The emotional map

Finally, another region of the brain contains the primary visceral map, which represents the internal organs of the body — the heart, lungs, liver, stomach, intestines, and others.

This map, highly developed in humans, gives us access to our internal sensations, something few other species experience.
We feel emotions such as anger, disgust, sadness, joy, and shame thanks to this visceral mapping. These internal signals form the basis of deep emotional awareness — the voice of our consciousness, the melody of our existence, and the root of our sense of self.

References:
Sandra and Matthew Blakeslee, “The Body Has a Mind of Its Own” (2008)

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