The progression of discussion in regards to localized areas of the brain and their respective function. by Isabelle Smith

1811 - Julien Jean Legallois discovers respiratory center in medulla

smith15517 — 2024-02-05 20:37:14 UTC

JJ. Legallois performed experiments through a method of decapitation of rabbits. He realized that the headless rabbits could still breathe and "survive" at certain points of dissection of the brainstem for some time, but dissection past a certain part of the brain stem would stop respiration immediately. He then isolated a part of the brain stem the part of the brain stem that the respiratory function was located. He did this by opening the skull and removing portions of the brain. He then realized he could remove the parts of the cerebellum, cerebrum, and parts of the brain stem and respiration would continue. The specific part of the brain stem that he identified as the point essential for respiration was the medulla oblongata, this is where the vagus nerve originates. This is where he established the "primary seat of life" was in the brain stem and not other parts of the brain.

Source: https://neuroscientificallychallenged.com/posts/history-of-neuroscience-julien-jean-cesar-legallois

1823 - Marie-Jean-Pierre Flourens states that cerebellum regulates motor activity

smith15517 — 2024-02-05 20:37:29 UTC

Luigi Galvani, an Italian physician and physicist, showed that muscle contraction is due to electricity. Luigi Ronaldo, an Italian anatomist, thought that since the brain generates the movement, it must contain a device generating electricity.He argued that, if the cerebellum is the battery that produces electricity for muscle activity, its removal would produce paralysis. He ran experiments observing a young goat with no cerebellum, and eventually came to the conclusion that the cerebellum is a motor structure. He also believed that the cerebellum generates the electricity which produces the movement. This is not necessarily sit right with Marie Jean Pierre Fluorens. Flourens observed animals without a cerebellum and found that some were still able to move, some with issues in regards to balance. He eventually concluded that the role of the cerebellum “is to put in order or to coordinate movements wanted by certain parts of the nervous system, excited by others”. In other words, he determined that the cerebellum's function is to organize or synchronize movements desired by specific nervous system components, which are stimulated by others.

Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4552144/

1876 - David Ferrier publishes The Functions of the Brain

smith15517 — 2024-02-05 20:37:43 UTC

David Ferrier, a Scottish neurologist, is known for his contributions to the field of neurophysiology, particularly in the study of the brain's motor functions. Ferrier discusses how our thoughts, feelings, and sensations can lead to movements in our limbs within this book. He further expresses that the cerebral hemispheres seem important for generating ideas and emotions linked to these movements. Through experimentation it is shown that movements can still happen without these hemispheres, suggesting they are not absolutely necessary but play a supporting role. Some of the experiment he observed these functions through was the variations of the normal knee-jerk reaction and their relation to activity in the central nervous system.

Sources: https://www-jstor-org.proxy.lib.ohio-state.edu/stable/1411238?seq=4

Who is my docent? Robert B. Todd and his contributions to the field of neuroscience

smith15517 — 2024-02-05 20:37:56 UTC

Robert B. Todd was a pioneering mirobiologist and conducted neurohistological studies that contributed to the application of Schwann's cell theory to the nervous system. Neurohistology is a branch of histology that is concerned with the central nervous system. He discussed many different studies and wrote a textbook on the anatomy of the brain, spinal cord, and ganglion, as well as other books outlining his findings. He was among the first to realize the continuity between nerve cell bodies and axons ("axis cylinders"). Todd also identified the insulating properties of Schwann's "white substance" (myelin) in facilitating nerve conduction. He has made mentionable findings within the field of neuroscience and completely introduced the concept of brain electricity and explored electrical discharges in epilepsy. He had a huge contribution to the cell theory and cell doctrine, which is what states that the brain is made up of individual cells.

Source:

https://pubmed.ncbi.nlm.nih.gov/21480036/

https://www.merriam-webster.com/medical/neurohistology#:~:text=%3A%20a%20branch%20of%20histology%20concerned%20with%20the%20nervous%20system

1836 - Marc Dax reads paper on left hemisphere damage effects on speech

smith15517 — 2024-02-05 20:38:38 UTC

In the year 1836, Marc Dax, a French military surgeon, clinically observed that injury to the left hemisphere of the brain frequently led to "a memory loss specifically for words." Dax's observations remained unpublished for nearly three decades until Paul Broca renewed interest in aphasia in the 1860s. In 1861, Broca presented cases linking aphasia to lesions in the left frontal lobe, and in 1863, he detailed eight additional cases. After two more years of clinical study, Broca concluded that "the loss of speech without the paralysis of the organs of articulation and without the destruction of the intellect, is linked to lesions of the third frontal convolution." This means that Marc Dax made the observation through clinical research about the lateralization of language, and Broca could further link his findings to that to the language disorder of aphasia's.

Source:

https://link.springer.com/chapter/10.1007/978-1-4899-1857-4_20#:~:text=In%201836%2C%20Marc%20Dax%2C%20a,Dax%2C%201865%2F1984).

Phrenology - the initial view of localized brain regions in relation to traits

smith15517 — 2024-02-05 20:39:38 UTC

Phrenology is a psuedoscience that was an attempt to link ersonality traits with scalp shape, with the assumption that scalp morphology reflects underlying brain function. Franz Joseph Gall, a Viennese physiologist, invented phrenology in the late 18th century, and it was later popularized by his students Spurzheim and Combe across Europe and the United States. This psuedoscience identified 26 to 40 brain regions or "organs" associated with mental faculties, with the belief that larger regions indicated greater use. Gall maintained the belief that phrenological brain traits were static, but the scientists following his work argued in favor of their adaptability. They employed phrenology to substantiate early biological theories on crime and to provide a rationale for educational strategies related to social class during the 19th century. Although now obsolete, phrenology significantly influenced neuroscience's development, contributing ideas about specific brain regions controlling certain functions.

Source:

https://www.simplypsychology.org/phrenology.html

Lesion studies in contemporary neuroscience

smith15517 — 2024-02-05 20:57:21 UTC

Lesion studies, where scientists examine brain damage effects, are crucial for understanding how our minds work. These studies, done in both humans and primates, offer unique strengths compared to other methods. New methods are being developed to ask even more questions about brain injuries. These studies help connect basic scientific knowledge to real-life behaviors in clinics and everyday situations. The future of neuroscience depends on testing ideas with different approaches, like studying brain lesions, manipulating brain activity, and looking at how activity in the brain correlates with behavior. Much of the clinical research done in this field is on rodents, because it would not be ethical to give human participants permanent brain damage in order to observe the effects of lesions in certain parts of the brain. There are invasive and non invasive ways of creating brain lesions, those being optogenetics and chemogenetics (invasive technique) and transcranial magnetic stimulation and transcranial focal ultrasound (non invasive). The neuroimaging techniques like PET, fMRI, and electrophysiology, allow us to visualize and improve the lesion studies. There is still doing research in the field in order to observe behavioral differences in non human subjects in order to assess functional aspects of the location of lesion.

Source:

https://www.sciencedirect.com/science/article/pii/S1364661319301329