“Two little humans”: Journeys to the brain-3

The little human”:

image source: Wikimedia Commons 

This journey will go through “Two little humans” who “live” on the brain surface. Dr Wilder Penfield and Edwin Boldrey “discovered” them in 1937.

This is an amazing story.

This journey will go through “Two little humans” who “live” on the brain surface. While working at McGill University in 1937, Dr Wilder Penfield and Edwin Boldrey began mapping corresponding brain regions that receive sensory information from the skin areas. Not only that, they mapped corresponding brain regions that send signals to move the body parts. This laborious exercise became possible because they were operating under local anaesthesia.

Together with Edwin Boldrey, he published their story in the “Brain” journal, writing a 50-page-long article with drawings. They found that our brain surface carries specific areas that exactly correspond to and account for different body regions. It is exactly similar to two little humans (humanoids) lying on the surface brain.

Figure 1: Dr Penfield and Boldrey and their little men Courtesy: https://academic.oup.com/brain/article/140/11/3055/4566636

These “Two little humans” (Figure 1) – now famously called “Homunculus of the brain” – lie along the Central Sulcus, which separates the Frontal lobe from the Parietal and Temporal lobes.

Homunculus in the brain

Figure 2 depicts the two little humans who lie along the Central sulcus – a groove that separates the Frontal lobe from the Parietal lobe (You can read this on the Journeys to the brain -2: A walk over the brain surface).

File:BA312 - Primary Somatosensory Cortex - lateral view - with homunculus.png

Figure 2: Left homunculus

Source: Wikimedia commons: Polygon data are from BodyParts3D[1]. Author: Polygon data were generated by Database Center for Life Science(DBCLS)[2]. Permission: under the license of CC BY SA 2.1.

As you can see in Figure 3 (below), the upper inside surface area controls our feet and legs. Let us start with Figure 2. When we climb, we will step on the areas that receive information from and send commands to the facial structures. Further up, we will find areas that receive the information and send instructions to move. It follows a highly organized distinct pattern. And, the more complex the job is, the larger the designated area.

<strong>Figure 4: Image source</strong>: <a href="https://upload.wikimedia.org/wikipedia/commons/thumb/c/c4/1421_Sensory_Homunculus.jpg/482px-1421_Sensory_Homunculus.jpg">Wikimedia Commons </a>

Figure 3: Homunculus regions

Source: Wikimedia commons: OpenStax College Anatomy & Physiology, Connexions Web site:  http://cnx.org/content/col11496/1.6/, Jun 19, 2013, under the license of creative commons. CC BY 3.0

You can read about the brain’s blood supply by joining me on another journey.   

Author: Prasantha De Silva

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