Language and the brain

The science that deals with the
relationship between language and brain
is called neurolinguistics.
Although the study of the relationship
between language and brain is still in its
infancy, much has been learned about
which parts of the brain are involved in
various aspects of language production
and comprehension.

Language: the system of words or signs that
people use to express thoughts and feelings to
each other.

Nervous System
Central nervous
system Brain and spinal
cord
Peripheral nervous
system
nerves
brain
ears
face
Rest of
body
Spinal
cord
nose
eyes
Sensory
nerves
environment
Spinal cord
brain

Brain
structure:
• The brain is composed of nerve cells called neurons.
• 1,400 grammes. Although the brain accounts for only about 2 per
cent of total body weight, it consumes about 20 per cent of the
oxygen the body uses while at rest.
• The most complex 1,400 grammes in the galaxy.
• the Greek philosopher Aristotle.
• 10 billion neurons
• Different regions of the brain are specialized: hearing, sight, bodily
sensations, etc.

Cerebral
hemisphere
Left brain
Right brain

• 87–92% is right-handed
• 95% of right-handers, the left side
of the brain is dominant for
language.
• 10% is left-handed
• 60-70% of left-handers, the left side
of brain is used for language.

in the 1860s and 1870s, Paul Broca and Karl Wernicke observed
that people who had damage to a particular area on the left side
of the brain had speech and language problems. The two
language areas of the brain that are important for language now
bear their names: Broca's area and Wernicke's area
Each hemisphere of the brain is dominant for other behaviors.
For example, it appears that the right brain is dominant for
spatial abilities, face recognition, visual imagery and music.
The left brain may be more dominant for calculations, math
and logical abilities

few left-handers have a mirror image representation for language.
Rather, they tend to show significant language representation in both
hemispheres. Thus, left- handers are generally less lateralized for
language.

Imagine that you could open the top of a living human being’s skull and observe the brain
while the individual is engaged in activities such as reading, writing, watching a hockey
game, or having a heated argument. What would you see? The answer is – nothing. To the
outside observer, the working brain shows no evidence of its activity. This is clearly a
problem for the field of neurolinguistics, which requires the use of special investigative
techniques to uncover the secrets of where and how language is processed in the brain.
Recent decades have seen a number of technological advances that have
greatly facilitated the investigation of the question: what is going on in the
brain when people are engaged in language behavior?

Autopsy studies
Until recently the only way to study the brain was through Autopsy studies.
This this technique was most often carried out with patients who were
admitted to hospitals displaying a neurological disorder. Subsequent to his or
her death, the brain was examined to determine which areas were damaged.
By comparing the area of brain damage and the type of disorder the patient
displayed while alive, neurologists could develop theories about the role of the
damaged brain parts in normal brain functioning.

A famous example of this type of analysis comes from the work of Paul Broca. In
1860, Broca observed a patient who had been hospitalized for more than twenty
years in paris. The patient was almost completely unable to speak, but appeared
to understand everything that was said to him. Towards the end of his life (he
died at fifty-seven), he also developed a paralysis of the right arm and leg.
Immediately after the patient’s death, Broca examined the brain. It showed
severe damage in the lower rear area of the left frontal lobe. Broca concluded
that because the patient was unable to speak, this part of the frontal lobe must
normally be responsible for speech production. Since that time, many other
studies have supported Broca’s conclusions. The impairment of the ability to
speak as a result of the brain is called Broca’s aphasia

Autopsy analysis has been and continues to be an important tool in the
understanding of the brain. But an autopsy can be carried out only after
the patient’s death.
Modern brain-imaging techniques have greatly increased our knowledge of
where language processing takes place in the brain. It has been found, for
example, that when subjects speak, much blood flows to the left hemisphere
of the cortex and to Broca’s area in particular. when subjects read, much blood
flows to the occipital lobe and other areas of the left hemisphere.

Dichotic listening studies
Each hemisphere is primarily wired to the opposite side of the body
(including the head). So, most of the input to your right ear goes to the
left hemisphere of your brain.
if you are right-handed, you will most probably be able to verify this by
observing the difference between holding a telephone receiver to your
right ear and holding it to your left ear during a conversation.

Aphasia: the loss of language ability as a result of
damage to the brain. The most common cause of
aphasia is stroke. A stroke occurs when the normal
flow of blood to the brain is disrupted, preventing
neurons from receiving oxygen and nutrients. Aphasia
can also be caused by blows to the head, brain
infection, brain tumours, and hemorrhage. For most
people, these are areas on the left side (hemisphere)
of the brain.Types of aphasia:
• Fluent Aphasia: the inability to understand the
language of others and the production of less
meaningful speech then mromal.
• Non-fluent aphasia: difficulty producing fluent,
articulated, or self-initiated speech.

Language has existed for about two
million years, but it is only in the last 150
that we have begun to understand what
happens when we listen and speak.

O'Grady, Archibald, Katamba (2011). Contemporary
linguistics: an introduction
Source

Language and the brain

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