In the 19th century, there were two major discussions about the brain. One was related to nerve function and electricity, and the other was related to phrenology. Phrenology was a popular theory in Europe that explained personality as being specific to certain brain areas. This theory argued that the shape of the skull was indicative of the brain's shape and that a person's personality could be deduced from feeling slight bumps in their Cranium.
Despite the lack of experimental evidence, phrenology was widely supported by the elites of France and England in the first half of the 19th century. However, it was not accepted by scientific circles and received much criticism, leading to its eventual falling from grace in the second half of the century.
Phrenological arguments of brain function were indicative of the thinking of the time, with widespread arguments taking place in scholarly circles between those who argued that the brain functions as a whole and those who, like phrenology, saw these different functionalities taking place in different brain areas.
It wasn't long until evidence of the localization of function was found. This evidence came from studies of patients who had impaired language capabilities due to lesions in their frontal lobes. These were firstly identified in research conducted by Jean-Baptiste Balads, Paul Brocker, and Carl Vernica.
Although Balads research like the type of localization we are now used to see it identified the general area of speech capacity to be in the frontal lobe, and most importantly, it served as a jumping point for further studies and claims. Brocker, a French physician, initially identified, in the case study of eight of his patients, lesions to a specific brain area, which he identified as the main speech production part of the brain. He later supported these claims with further proof, aided by the work of Gustav and Mark Ducks as Mark had identified this area much earlier than Broca, although it was later confirmed that Broca was not aware of this.
Although Brocker had argued that this area of the brain was the origin of all language processing and production, this was soon disproven by Vernica, who demonstrated how another part of the brain was highly involved in language processing, demonstrating how complex the brain is and how multiple areas can be involved in a specific function.
The age of brain function localization had begun, and it continues until now, with the argument between localization and widespread functionality continuing to this day. This discussion is fundamental to Neuroscience.
One apparent solution to the problem of consciousness that arose during this century was the recently discovered brain capacity for inhibition. Inhibition was initially introduced as the opposite of excitation of movement and was thought to be a fundamental building block of consciousness and behavior. Using this newfound process, many theories and models quickly appeared, although they all seemed to lack evidence and be very simplistic.
However, inhibition did represent a massive step forward in brain function and understanding as it presented researchers with the idea, still prevalent today, that one of the brain's main functions is that of control of the body, with Francis Ansti using the example of anesthetics and drugs to make the leaping logic to control. As he argued, these substances prevented the brain from controlling the body through inhibition.
Another fundamental insight gained during the final decades of the 19th century was related to perception. Hermann von Helmholtz suggested that the brain was not simply registering the stimulus when perceiving a sensation, but that it was making assumptions about the nature of the stimulus. For example, the brain assumes the existence of 3D vision based on the processing of visual stimuli. This shift in mindset from a passive, simply observant and reactive brain to a more active organ was crucial to understanding perception as an imperfect and selective process.
Neuroscience has come a long way since the 19th century, and it continues to evolve with new theories, models, and evidence. One notable trend in neuroscience is the speed at which ideas develop, compared to the slow progress of the past. This trend is likely to continue, with scientific papers published just a few years ago sometimes considered obsolete. Nonetheless, the past still informs the present, and it is essential to understand the history of neuroscience to appreciate its current state.
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