hemispheric asymmetries and contralateral control by Maxine Berger

Broca's Area

maxineberger123 — 2025-02-04 00:03:37 UTC

In France 1861, Paul Broca discovered an area in the left hemisphere that when damaged resulted in expressive aphasia (the inability to produce speech, though still able to comprehend it). This contributed to the understanding of hemispheric asymmetries in function and contradicted Franz Joseph Gall's view of bilateral function in brain areas.

With the discovery of Broca's Area, it became clear that the left hemisphere was dominant for language due to this clinical observations. Broca's discovery occurred after Jean-Baptiste Bouillaud postulated there was an area of the brain localized for speech production, though did not make the observation that this occurred in the left hemisphere. Recognizing functional differences between hemispheres was pursued after the discovery of Broca's Area.

Source:

https://www.sciencedirect.com/science/article/pii/S0093934X08001636

Wernicke's Area

maxineberger123 — 2025-02-04 00:22:55 UTC

Carl Wernicke discovered Wernicke's area in Germany in 1874. Wernicke's area is localized to the left hemisphere and is responsible for the comprehension of speech. Wernicke observed patients with damage to the superior temporal gyrus, and noticed they presented with anomia (difficulty retrieving words) and trouble comprehending language, though fluent production of speech.

The artifact presented is a page from his work of literature "(“The Aphasia Symptom-Complex: A Psychological Study on an Anatomic Basis”) in 1874. He describes his findings and postulates the Wernicke Arc in which Broca's area is connected to Wernicke for language processing. His work built upon Broca's discovery in the 1860s, and furthers the hemispheric asymmetry sentiment that was was not in effect prior to Broca.

Source: https://www.sciencedirect.com/science/article/pii/S1878875024003164

Ferrier's maps of the brain

maxineberger123 — 2025-02-04 00:41:00 UTC

The artifact presented above is a map of the brain constructed by David Ferrier in 1886 in London from his work of literature "The Functions of the Brain". Ferrier performed experiments on animals via cortical stimulation of the motor cortex to determine localization and functionalization. His work culminated into a somatotopic map of the brain. He postulated distinct boundaries for cortical areas. Ferrier observed contralateral effects when lesioning either the left or right hemisphere. His experiments showed hemispheric asymmetry due to control over different sides of the body regarding the motor cortex. His work built off of Fritz and Hitzig's previous observation of this effect.

Source: https://neupsykey.com/mapping-and-lesioning-the-living-brain/

John Hughlings-Jackson and the lateralization of emotion

maxineberger123 — 2025-02-04 02:16:45 UTC

The artifact displayed above is a painting of John Hughlings-Jackson who conducted most of his brain lateralization work in London in his lifetime (1835-1911) following Broca and Wernicke's language center localization discoveries. He hypothesized the emotional control center in the brain was focused in the right hemisphere. He noted that damage to the right hemisphere lead influenced skewed perception and emotional processing. This was an important step towards understanding the big picture functional variance between hemispheres. In 1874, Jackson came up with the duality of the brain hypothesis which is a hierarchical model of the nervous system. This essential denotes levels of cognitive function and provides insight into the view of the mind as a function of the brain.

source: https://pmc.ncbi.nlm.nih.gov/articles/PMC3737467/?utm_source=chatgpt.com

Fritsch & Hitzig on contralateral control

maxineberger123 — 2025-02-04 02:33:05 UTC

The artifact is a drawing done by Fritsch and Hitzig in 1870 Germany depicting motor results of electrical stimulation of a dog cortex. Previous work done by Galvani and Volta inspired them to utilize the electrical battery to pioneer neuroscience. Fritsch and Hitzig noted the contralateral side of the body experienced movement when an electrical stimulation was applied to a hemisphere. This paved the way for David Ferrier to begin his somatotopic mapping.

Source: https://neupsykey.com/mapping-and-lesioning-the-living-brain/

Docent - Paul Broca

maxineberger123 — 2025-02-04 03:00:55 UTC

Paul Broca (1824-1880) made numerous pivotal discoveries as a French neuroscientist and anatomist. He represents a pivotal transition from the phrenology era of Franz Gall to a more modern view of brain localization. He was the seed crystal for the brain functionalization studies that occurred after his discovery of Broca's Area in 1861. This was also incredibly influential fort he understanding of the brain's asymmetries among the two hemispheres. He would be the most adept docent due to his interest and expertise in brain anatomy and lateralization. Without his discoveries, the course of neuroscience may have looked completely different.

Source: https://neuroscientificallychallenged.com/posts/history-of-neuroscience-paul-broca#

Transcranial Magnetic stimulation

maxineberger123 — 2025-02-04 03:40:43 UTC

Transcranial magnetic stimulation (TMS) is a modern day method of brain lateralization utilizing a magnetic field and the electrical activity of the brain. TMS is currently used all over the world to selectively stimulate and inhibit parts of the brain to observe function. TMS is used as both a research method and as a treatment for numerous disorders such as depression and OCD. TMS is used for motor cortex and visual cortex mapping in modern day which corresponds to Fritsch & Hitzig and Ferrier's work of electrical stimulation to observe motor function. This artifact is important because it demonstrates how previous advances in science morph into what we now perceive as cutting edge science. It shows the potential for advances and how current research is shaping the future. https://www.sciencedirect.com/science/article/abs/pii/S1042368010001130?via%3Dihub