To continue our journey around the annals of the history of the study of the brain, is worth mentioning
that the neuroanatomy has undergone revolutionary changes in the last decades.
That leap has been made possible thanks to the introduction of new imaging
techniques such as: X-Ray computed tomography (CT, also called computed
tomography CT), (PET) Positron Emission Tomography and Magnetic Resonance Imaging (MRI), thanks all these tools, it is possible to observe the structure and
activity of the brain in unprecedented detail.
All those datas, specially volumetric and structural
studies, CT and MRI are of crucial importance to understand brain differences and give answer to many questions, specially about neuro degenerative diseases (Allen, Bruss and Damasio, 2005).
However, this neuro technological revolution did not begin from nothing or yesterday, all these amazing possibilities probably began in 1783 with physician
Luigi Galvani who was a passionate about anatomy, and who had the idea of using electricity to move the leg of a dead frog. Does that sounds like Frankenstein?, what was this idea of moving a leg of a dead frog?, well, he
began efforts to stimulate and visualize neural activity, and some explain this open a door to analyze living brains now.
Many years later, in 1937, a neuroscientist
Charles Sherrington could see points of light signals in neuronal activity,
this surprised to a Spanish physiologist, Jose Delgado, and he used radio
waves to study the brain of a bull in 1963.
But it was not until 1971 that voltage
fluorescent studies begin to become popular, and during decade of 1980 with the fluorescent dye, it was possible to see how calcium concentration changes while it's synthesized in a cell, and this opened
doors for the study of the brain on a larger scale (Miesenbock, 2008).
I can't forget during this
tour, including another researcher that made important contributions to the study
of the brain, so I must remember to Korbinian Broadman, who conducted
research that allowed to distinguish 52 brain regions, thanks to his
studies on cerebral cytoarchitecture made on histological samples that permitted find anatomical definitions of different brains, and his studies currently are known as areas of Broadman which are used to mapping the
brain, since they have been associated with specific activities and brain functions (Kandel, Schwartz & Jessel, 2000).
Among the researchers
that devoted his time to understand the functions relate to anatomical
Broadmann's areas there is a name, Wilder Penfield, who was a Canadian neurosurgeon and during his surgeries he stimulated with an electric pulse small points on the surface of
the brain at the same time he asked to patient if he or she felt something (this was necessary to determine
exactly which region he had to operate).
He found out that when different regions of the brain are
stimulated in this way, the patient could have different perceptions (Harrison,
Ayling & Murphy, 2012). For example, when it was stimulated the occipital
lobe, patient saw flashes of light, but if it was stimulated the parietal area, persons could heard buzzing, or maybe noticed tingling in any part of the skin, or maybe if stimulation was done in another
region the patient begin moving any part of the body.
Based on these observations, Penfield made a neurocortex map, since he could find where each sensory
modality was represented in a specific part of the cerebral cortex, and he figured out it was not only possible to relate a cortical region for each sensory modality, but that each part of the
body had assigned to a specific region in the cortex, but on the opposite side of the
body; for example a patient responded to a electrical stimulation on
the left motor cortex with a movement of right leg.
Therefore all his research made possible to recognize areas on the surface of the cerebral cortex and relate
them to different processes, finding in each patient areas where it was
possible to recognize a specific taste, a vivid childhood memory or the fragment of
a long-forgotten melody (Sagan, 2003; Shreeve, 2005; Library of archives of
Canada, 2009).
One of the reported cases, is about a patient who during a brain surgery said, he could listened with luxury of detail,
a interpretation of a composition of orchestral when it stimulated an area
specified in his brain with an electrode. Other patients experienced a specific
emotion, a sense of familiarity or the full memory of an experience of
childhood, all simultaneously, forgetting the fact they were in an
operating room talking to the surgeon.
Some patients explained these memories
as small dreams, but did not appear
in them the symbolism characteristic of a reverie (Shepperd, 2004). In the
specific case of electrical stimulation of the occipital lobe, which is related
to the vision, a patient said to be seeing butterflies flying around,
so real and palpable, that even lying on the operating table, stretched out the
hand to catch them (Sagan, 2003).
All this experiences gave a good idea how the brain is divided into areas and allowed to map and understand much better those parcels
of information processing.
However, even though there have been isolated area and process
specific, neuroscience still cannot understand how it is possible to carry out
the processing of information and the storage and handling of data that day to
allow us to understand the environment and adapt to it, and I think the main question of neuroscience is: how do electric and chemical impulses become subjective experiences?.
References:
Allen, J.; Bruss, j.
& Damasio, H. (2005) structure of the human brain. Research and science. 23 - January. 68-75.
Harrison TC., Ayling OGS, Murphy, TH. (2012) Cortical Disctinct circuit mechanisms for complex forelimb movement motor and map topography. Neuron. 72 (2) 397-409.
Kandel, E.; J.H Schwartz, Jessell, t. (2000) h Principles of Neural Science. New York: McGraw-Hill.
Library Archives of Canada (2009) Famous Canadian Physicians. (Available online): http://www.collectionscanada.gc.ca/physicians/030002-2400-e.html.
Miesenbock, g. (2008) Lighting up the brain. Scientific American . Vol. 299. NUM. 4 34-43.
Sagan, C. (2003) the Dragons of Eden: speculations on the evolution of human intelligence. Barcelona. Criticism.
Shepherd, g. (2004) The synaptic organization of the brain. Oxford, University press.
Shreeve, j. (2005) Cornina complet brain: she is all... is here. National Geographic. 207 (3) 6-12.
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