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In 1861, two scientists got into
a very brainy argument.

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Specifically, they had opposing ideas
of how speech and memory

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operated within the human brain.

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Ernest Aubertin, 
with his localistic model,

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argued that a particular region
or the brain

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was devoted to each separate process.

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Pierre Gratiolet, on the other hand,
argued for the distributed model,

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where different regions work together

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to accomplish all of these 
various functions.

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The debate they began reverberated
throughout the rest of the century,

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involving some of the greatest scientific
minds of the time.

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Aubertin and his localistic model
had some big names on his side.

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In the 17th century, René Descartes
had assigned the quality

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of free will and the human soul
to the pineal gland.

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And in the late 18th century, a young
student named Franz Joseph Gall

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had observed that the best memorizers
in his class had the most prominent eyes

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and decided that this was due 
to higher development

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in the adjacent part of the brain.

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As a physician, Gall went on to establish
the study of phrenology,

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which held that strong mental faculties
corresponded to

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highly developed brain regions, observable
as bumps in the skull.

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The widespread popularity of phrenology
throughout the early 19th century

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tipped the scales towards 
Aubertin's localism.

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But the problem was that Gall had never
bothered to scientifically test

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whether the individual brain maps
he had constructed

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applied to all people.

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And in the 1840's, Pierre Flourens
challenged phrenology

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by selectively destroying parts
of animal brains

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and observing which functions were lost.

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Flourens found that damaging the cortex

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interfered with judgement or movement
in general,

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but failed to identify any region
associated with one specific function,

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concluding that the cortex carried out
brain functions as an entire unit.

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Flourens had scored a victory 
for Gratiolet, but it was not to last.

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Gall's former student, 
Jean-Baptiste Bouillaud,

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challenged Flourens' conclusion,

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observing that patients 
with speech disorders

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all had damage to the frontal lobe.

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And after Paul Broca's 1861 autopsy of a
patient who had lost the power

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to produce speech, but not the power
to understand it,

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revealed highly localized 
frontal lobe damage,

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the distributed model seemed doomed.

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Localism took off.

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In the 1870's, Karl Wernicke associated
part of the left temporal lobe

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with speech comprehension.

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Soon after, Eduard Hitzig and 
Gustav Fritsch

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stimulated a dog's cortex and discovered
a frontal lobe region

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responsible for muscular movements.

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Building on their work, David Ferrier
mapped each piece of cortex

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associated with moving a part of the body.

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And in 1909, Korbinian Brodmann built
his own cortex map with 52 separate areas.

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It appeared that the victory of Aubertin's
localistic model was sealed.

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But neurologist Karl Wernicke had come up
with an interesting idea.

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He reasoned that since the regions for
speech production and comprehension

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were not adjacent,

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then injuring the area 
connecting them might result

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in a special type of language loss,
now known as receptive aphasia.

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Wernicke's connectionist model helped
explain disorders

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that didn't result from the dysfunction 
of just one area.

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Modern neuroscience tools reveal a brain
more complex than

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Gratiolet, Aubertin,
or even Wernicke imagined.

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Today, the hippocampus is associated
with two distinct brain functions:

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creating memories and processing
location in space.

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We also now measure 
two kinds of connectivity:

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anatomical connectivity between 
two adjoining

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regions of cortex working together,

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and functional connectivity 
between separated regions

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working together to
accomplish one process.

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A seemingly basic function like vision

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is actually composed 
of many smaller functions,

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with different parts 
of the cortex representing

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shape, color and location in space.

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When certain areas stop functioning,
we may recognize an object,

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but not see it, or vice versa.

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There are even different kinds of memory
for facts and for routines.

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And remembering something 
like your first bicycle

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involves a network of different regions
each representing the concept

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of vehicles, the bicycle's shape, 
the sound of the bell,

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and the emotions associated 
with that memory.

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In the end, both Gratiolet and Aubertin
turned out to be right.

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And we still use both of their models
to understand how cognition happens.

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For example, we can now measure brain
activity on such a fine time scale

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that we can see the individual localized
processes that comprise

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a single act of remembering.

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But it is the integration of these
different processes and regions

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that creates the coherent memory
we experience.

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The supposedly competing theories
prove to be two aspects

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of a more comprehensive model,

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which will in turn be revised and refined


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as our scientific techologies and methods
for understanding the brain improve.