Transcript Brain Reorganization

Module 3
The Brain
*The Brain
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* Electroencephalograph (EEG):
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records “waves” of electrical activity in the brain using metal
electrodes
* Computerized axial tomograph (CAT):
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thousands of X-ray photos of the brain are combined to form a crosssectional picture
* Magnetic resonance imaging (MRI):
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produces three-dimensional images of the brain’s soft tissues by
detecting magnetic activity from nuclear particles in brain molecules
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* Positron emission tomography (PET): measures neural
activity in different brain regions over several
minutes by monitoring sugar glucose consumption
* Functional magnetic resonance imaging (fMRI): measures
neural activity in different brain regions averaged
over seconds by monitoring blood oxygen levels
*PET Scan
*MRI Scan
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* Their names come from their physical location in the
human embryo.
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Hindbrain: Located above the spinal cord,
Midbrain: Located above the hindbrain
Forebrain: Located above the midbrain
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*Hindbrain consists of:
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Medulla: controls breathing, heart rate,
swallowing, digestion, and posture
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Pons: associated with sleep and arousal
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Cerebellum: regulates and coordinates body
movement and may play a role in learning
*The
Cerebellum
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Reticular formation:
* regulates and maintains
consciousness
* plays an important role in
controlling arousal
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Controls complex emotional reactions, cognitive
processes, and movement patterns. Consists of:
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Thalamus: the brain’s sensory relay station
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Limbic system: influences fear, aggression, and new
memories
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Cerebral cortex: located on top of these structures;
the most complex part of the brain
* Brain’s Sensory Switchboard
* Directs incoming information from the sensory
systems (except smell) to the appropriate
location on the cortex.
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*The Brainstem and
Thalamus
*a doughnut-shaped system of neural structures at the
border of the brainstem and cerebral hemispheres
*associated with emotions such as fear and aggression and
drives such as those for food and sex
*includes the hypothalamus, hippocampus and amygdala
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*The Limbic System
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*neural structure lying below (hypo) the
thalamus
*directs several maintenance activities
* eating
* drinking
* body temperature
*helps govern the endocrine system via the
pituitary gland
*linked to emotion
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*Structure linked to the processing/formation of
new explicit memories
*Manufactures new neurons
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*two almond-shaped neural clusters
that are components of the limbic
system and are linked to emotion,
especially rage and fear
*The Limbic System
* Electrode implanted in reward center
*Main Parts of the Human Brain
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The cerebral cortex is divided into two rounded halves,
called the cerebral hemispheres.
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These hemispheres are connected together at the bottom
by the corpus callosum.
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Both hemispheres are divided into four major sections
called lobes:
*The Brain
*The Cerebral
Cortex
Cortical Localization
*Occipital Lobes
*include the visual areas, each of which
receives visual information from the
opposite visual field
*Temporal Lobes
*include the auditory areas, each of
which receives auditory information
primarily from the opposite ear
*Visual Cortex
* Functional MRI scan of
the visual cortex
activated by light
shown in the subject’s
eyes
*Visual and Auditory Cortex
*Cortical Localization
*Frontal Lobes
*involved in speaking and muscle
movements and in making plans and
judgments
*Parietal Lobes
*include the sensory cortex
*The Cerebral
Cortex
*The Cerebral Cortex
*Motor Cortex
*area at the rear of the frontal lobes
that controls voluntary movements
*Sensory Cortex
*area at the front of the parietal lobes
that registers and processes body
sensations
*Association Areas
*Areas of the cerebral
cortex that are not
involved in primary motor
or sensory functions
*Involved in higher mental
functions such as learning,
remembering, thinking, and
speaking
*Cerebral Cortex *Aphasia
Speech
* impairment of language, usually caused by left hemisphere
damage either to Broca’s area (impairing speaking) or to
Wernicke’s area (impairing understanding)
*Broca’s Area
* an area of the frontal lobe that directs the muscle movements
involved in speech
*Wernicke’s Area
* an area of the left temporal lobe involved in language
comprehension and expression
* Specialization and Integration
*Brain Activity when Hearing,
Seeing & Speaking Words
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*Right hemisphere: superior to the left
hemisphere in visual and spatial tasks,
recognizing nonlinguistic sounds, identifying
faces, and perceiving and expressing emotions
*Left hemisphere: superior to the right
hemisphere at language, logic, and providing
explanations for events
*Women may be more likely than men to use both
hemispheres for language (their brains are more
bilateralized).
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*65% have speech on the left (95 %
RH)
*Weak correlations:
* + gifted & creative
* - reading disabilities, epilepsy,
alcoholism, schizophrenia, allergies,
MR
*Brain
Reorganization
• Corpus Callosum
– large bundle of neural fibers connecting the
two brain hemispheres and carrying
messages between the hemispheres
*Brain Reorganization
Corpus Callosum
*Brain
Reorganization
– Split Brain
– a condition in which the two hemispheres of
the brain are isolated by cutting the
connecting fibers (mainly those of the corpus
callosum) between them
*Brain
Reorganization
* The information highway
from the eyes to the brain
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Plasticity: the flexibility of the brain to alter its
neural connections following injury
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Hemispherectomy: a radical surgical procedure in
which one of the cerebral hemispheres is removed to
control life-threatening epileptic seizures. The
remaining healthy hemisphere takes over many of the
functions of the removed hemisphere.
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Plasticity is highest in childhood, but it also occurs in
older adults.
*Brain
Reorganization
-- the brain’s capacity for
modification as evident in brain
reorganization following damage
(functional plasticity)
-- and in experiments on the effects of
experience on brain development
*Structural Plasticity)
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Avoid Harmful Substances
Exercise
Eat Sensibly
Challenge Yourself Mentally
Wear Your Helmet/Seat Belt.
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Beneficial substances allowed to enter the brain
through the blood-brain barrier are blood gases,
such as oxygen, and small nutritional molecules.
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An important nutritional molecule transported
out of the bloodstream in this way is glucose.
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Scientists have learned how to trick the bloodbrain barrier into accepting therapeutic drugs
through the bloodstream to the brain.
*Blood-Brain Barrier