Homunculus
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- Dictionaryhomunculus/hɒˈmʌŋkjʊləs/
noun
- 1. a very small human or humanoid creature.
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The homunculus is commonly used today in scientific disciplines such as psychology as a teaching or memory tool to describe the distorted scale model of a human drawn or sculpted to reflect the relative space human body parts occupy on the somatosensory cortex (the sensory homunculus) and the motor cortex (the motor homunculus).
- Overview
- Origins of cortical homunculi
- Limitations and importance of modern models
homunculus, diminutive fully formed human body, historically believed to inhabit a germ cell (an egg or a sperm) and to have the capacity to increase in size, giving rise to an adult human. The word homunculus is Latin for “little man” or “little person.”
The homunculus has had a colourful history in Arab-Islamic and European cultures. In medieval and early modern times, the term was commonly used to refer to an artificial humanlike being that people thought could be created through alchemy. In early modern scholarly texts, however, a homunculus was depicted by natural philosophers as a tiny person contained within an individual sperm. This depiction was used as a way of explaining human development in the womb.
The modern concept of the cortical homunculi emerged in 1937, when one such homunculus was presented in the journal Brain in an article written by neurologists Wilder Penfield and Edwin Boldrey. The two men had gathered data from 126 surgical patients who had been given only local anesthesia for their operations. When Penfield electrically stimulated different areas of the patients’ cerebral cortex during the operations, the patients were able to tell him where in their bodies they experienced feeling or movement.
Penfield and Boldrey mapped the sensory and motor data, associating it with areas of the motor cortex and sensory cortex. They then converted their data into rough visual images to show how the brain perceives body parts. According to their depictions, roughly one-third of the motor and sensory cortical areas was dedicated to the hands. Another third was associated with the face, lips, tongue, and pharynx. The remaining third was devoted to the rest of the body—the trunk, legs, and arms. The results of Penfield and Boldrey’s work suggested that the brain “sees” the human body very differently from the way the body appears physically.
Penfield and Boldrey’s cortical homunculus quickly captured the imagination of other individuals in the medical profession and the general public. Eventually, artists modeled the original image as two separate three-dimensional homunculi—one related to the sensory cortex and the other to the motor cortex. There were slight differences between the two figures; for instance, the motor homunculus had a larger face and hands than the sensory homunculus had.
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Although dramatic figures of cortical homunculi have been reproduced in various textbooks, encyclopedias, and medical texts as illustrations of cortical mapping, they oversimplify how the body’s sensorimotor signals are actually processed in the brain. The homunculi drawings and models suggest that there is a clear-cut, orderly separation between the sensory cortex and the motor cortex, but there is no such separation. The oversimplification reflected in the homunculi was due to the challenge of converting the original data points into images. To make that conversion, much of the information indicating functional overlap between the two regions of the cortex had to be sacrificed. There was no clear way to show such interconnectedness in a diagram or a sculpture. Paradoxically, the two separate homunculi helped create and perpetuate the misconception that the two cortical areas function separately.
In actuality, the brain processes signals from both cortices to operate the body. For example, in order to manipulate the hands, the brain receives sensory data—including touch, temperature, and spatial information—from the hands and then generates motor signals to move the muscles in the palms and fingers. The large network of sensorimotor pathways devoted to the hands gives humans the ability to make a vast range of movements, from gripping a hammer to playing a violin to performing a delicate surgical operation.
Homunculus is a Latin word for a little man or a miniature adult. It is also a term in the theory of preformation, which suggests that a fully formed individual is contained in a germ cell.
Mar 5, 2019 · In the past, however, it was in the field of alchemy that Medieval scientists sought to artificially create life. One of the beings that alchemists were purportedly able to create was the homunculus, meaning ‘little man’ in Latin. The homunculus is first referred to in alchemical writings of the 16 th century.
- Dhwty
Homunculus definition: an artificially made dwarf, supposedly produced in a flask by an alchemist.. See examples of HOMUNCULUS used in a sentence.
A homunculus might sound like something from a fantasy novel, but it’s a concept that has tickled the curiosity of thinkers for centuries. Imagine a tiny, fully formed human—this is the homunculus, a term that literally translates to ‘little man’ in Latin.
Sep 30, 2024 · Welcome to the fascinating world of the homunculus brain, where our cerebral cortex plays host to a distorted, yet incredibly important, model of our physical selves. The concept of the homunculus, Latin for “little man,” has captivated neuroscientists and casual observers alike since its discovery in the mid-20th century.
