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the
study of the biological and neural foundations of language
Cortex: surface of the brain "gray matter"
white matter: connecting fibers beneath
the cortex
  
cerebral hemispheres:
left/right halves of the brain
corpus callosum: network of 2 million
fibers connecting the hemispheres
contralateral brain function: left side
of brain controls functioning of right side of body and right hemisphere of brain
controls left side of body.
Modularity of the Brain
First indications came from phrenology - practice of determining personality
traits and abilities based on reading the bumps on the skull. Proposed by Franz
Joseph Gall in early 1800s. Phrenology has been discarded but Gall's concept
of modularity has been upheld.
Paul Broca - 1864: related language to
the left side of the brain, based on autopsies of people who had language deficits
and damage to the left frontal lobes of brian. This area came to be called Broca's
area
Broca's Aphasia: language disorder that results from injury to Broca's
area
Aphasia: any language disorder that results
from brain damage caused by disease or trauma
Carl Wernicke
- 1874 - identified aphasia in patients with damage to the back
left portion of brain. (Wernicke's area)
Wernicke's
aphasia: patients who spoke fluently but had numerous
lexical errors; using jargon and nonsense words. Had difficulty in comprehending
speech.
Does everyone have language functions in the left side of their brains? How about right-handed
people?
Discussion: is there an evolutionary purpose
for lateralization? What do you think could be the reason behind it?
New ways to discover brain functioning:
MRI (Magnetic
Resonance Imaging): Magnetic Resonance Imaging (MRI) is
a noninvasive method which utilizes the properties of magnetism to create
nondestructive, three dimensional, internal images of the soft tissues of
the body, including the brain, spinal cord and muscle. ( How MRI works)
PET (Positron Emission Tomography): shows metabolic activity of the brain (How PET works)
Images
from PET scans
SPECT/CT
scans: SPECT studies combine nuclear medicine (the use
of radioisotopes in the diagnosis of disease) with computed tomography. In
this technique, the patient either swallows or is injected with a radioisotope,
which travels to a target
organ. Concentrating in the target organ, the radioisotope emits
radiation, which is detected by a gamma camera that rotates around the
patient. The information obtained via the gamma camera is analyzed
by a computer, which creates a cross-sectional image of the target organ. SPECT
scans are frequently used to determine if a specific area of the body
is receiving
adequate blood flow.
Childhood brain lesions
Hemiplegic children: have lesions on one side of the brain; shows differing
cognitive abilities
Split brains
surgical severing of the corpus callosum - no communication between two side
of brainDichotic Listening
contralateral stimuli (opposite
side) outweigh ipsilateral stimuli
reason: stimuli don't have to cross the corpus callosum
(Discussion: Does this make sense? signals
from right ear go directly to left side of brain, not through right side
of brain; How about your use of the phone - do you hold it to your left ear
or your right war?)
EEG - based evidence: Event-related Brain Potentials
(ERPs)
Cognitive neurophysiology is the study of changes in brain function and
the relationship of such changes to thought processes. The primary physiological
signal that we measure is the electroencephalogram or EEG. The EEG reflects summated
potentials generated by the electrochemical signaling processes by which networks
of neurons process information. The EEG changes in predictable ways as a function
of level of alertness, type and/or intensity of mental activity, and particular
forms of brain pathology. We record the EEG by arrays of electrodes attached
with conductive gel to many locations across the scalp. Similar sensors are attached
to the face in the region of the eyes to record the electro-oculogram or EOG,
that is, the electrical potentials generated by eye movements and blinks. The
EOG can also provide useful information about mental state.
(Gevins 1997)
For a more in-depth explanation of ERPs: Coles & Rugg 1995
Other interesting applications of ERPs:
Brain Fingerprinting
for Counter-Terrorism
Language Perception & learning
strategies
Neural
basis of musicality
Historical Evidence for Brain Modularity: Studies
of Aphasia Carl Linnaeus (1745) studied jargon
aphasia, a disease in which the patient substitutes a semantically similar
word for the intended word.
Johannes Gesner (1770) attributed language difficulties to specific impairment
of language memory. He observed bilingual asymmetry in which an abbot who
had brain damage could read Latin but not German.
Broca's aphasics - agrammatic aphasia: utterances
without function words, problems understanding syntactic structure
Wernicke's aphasics - may produce fluent
but unintelligible speech, substitute one sound for another (table -> sable)
or one word for another. (chair ->
table) Also jargon
aphasia.
One way that has been tried to help such patients communicate is to have them
write the words they want to communicate. In England a Lightwriter has been used to
help aphasic patients communicate. Words can be typed and show up on two screens,
one for the writer and one for the person they want to communicate with.
Acquired dyslexics: people who lose the
ability to read after brain damage
Genetic Evidence for Language Autonomy
Linguistic savants: individuals who are handicapped
in certain spheres but remarkably talented in others
Specific Language
Impairment: Seems to have genetic basis, affect identical twins - support
modular view of language facility
FoxP2 is the first
identified gene that is specifically involved in speech and language development
in humans (not in book)
Language and Brain Development
The Critical Period: period from birth
to puberty when language acquisition proceeds easily
evidence: "wild" children, Genie, Chelsea
Bird Songs: some species learn calls, like these:
Male Chaffinch:  Female Chaffinch: 
 But the other's calls, like that of the
cuckoo, seem to be biologically determined
Origins of Human Language
Problem: spoken language existed long before written records are preserved.
Beliefs cloud the topic: monogenetic - belief that all langauges originated from
a single source (Tower of Babel story)
Exercises:
1. Roger Sperry
biography
Eccles biography
Fun with electrodes! Probe
the brain
References:
for your reference in doing papers that use online sources: see the APA's guide to online source citation
Coles, M.G.H., Rugg, M.D. (1995). Event-related brain potentials:
An introduction. In M. Rugg, M. Coles (Eds.), Electrophysiology of Mind. Oxford
University Press: Oxford, U.K. (PDF) Accessed February 6, 2005 at http://whalen.psych.udel.edu/667/1.What_is_ERP/ColesRugg1995chpt1.pdf
Gevins, A. (1997) Neural Signals of Cognition During Computer
Use. Accessed February 6, 2005 at http://cslu.cse.ogi.edu/nsf/isgw97/reports/gevins.html
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