Transcript The Structures of the Brain

 The brain is truly a remarkable organ; in fact, it is the
single most complex object in the known universe. It
consists of nerve cells (neurons) as well as support cells
(astrocytes, oligodendrocytes, and microglia), and has
the consistency in life of solidified jello. It lies
suspended in fluid (called cerebrospinal fluid, or CSF
for short) and is surrounded by several membranes
(called the meninges) all of which are enclosed within
a very solid and protective bony chamber, the skull.
The Brainstem is the
oldest part of the brain,
beginning where the
spinal cord swells and
enters the skull. It is
responsible for
automatic survival
functions.
The Medulla is the base of
the brainstem
It controls autonomic
functions and relays nerve
signals between the brain
and spinal cord.
respiration
blood pressure
heart rate
reflex arcs
vomiting
Pons - A nerve network involved in motor control and sensory
analysis...
Information from the ear first enters the brain in the Pons.
Certain parts are important for the level of consciousness
and for sleep.
The Reticular Formation controls:
Attention
Cardiac Reflexes
Motor Functions
Regulates Awareness
Relays Nerve Signals to the Cerebral Cortex
Sleep
ADHD Association
The is the brain’s sensory
switchboard, located on top
of the brainstem. It directs
messages to the sensory areas
in the cortex and transmits
replies to the cerebellum and
medulla.
- Not Smell
- The “little brain” attached to the rear of the brainstem. It
helps coordinate voluntary movements and balance.
-Controls leg and arm movements
-Damage causes awkward movement to the inability to stand
 Large clusters of neurons that work with the
cerebellum and cortex to control voluntary
movements.
 Determines course of action in movement
 How you ride a bike, swim, or jump off a bridge.
 Damage can lead to unwanted movement (Parkinson's)
 Processes information about
internal state
 Blood pressure
 Heart rate
 Respiration
 Smell, motivation, memory
 Emotional center
 Four focal areas:
 Thalamus
 Hypothalamus
 Amygdala
 Hippocampus
The Amygdala consists of two
almond-shaped neural clusters
linked Excitement, Arousal,
Fear.
-Discriminates objects for
organisms survival
-* Can I eat it?
-* Will it eat me?
-* Can I have sex with it?
 Determines what parts of information should be
stored into durable, lasting, neural traces in the cortex
 Helps us recall information by activating the parts of
the brain we used for that activity
 Extensive damage leads to an inability to retain long
term memories
The Hypothalamus lies below
(hypo) the thalamus.
-Directs several maintenance
activities like eating, drinking,
body temperature, and control
of emotions.
- It helps govern the endocrine
system via the pituitary gland.
- Monitors reward activities
-Thirst, Hunger, Sex Motivation
-Emotion, Stress, and Reward
Rats cross an electrified
grid for self-stimulation
when electrodes are
placed in their reward
center (hypothalamus,
top picture). When the
limbic system is
manipulated, a rat will
navigate fields or climb
up a tree (bottom
picture).
 The Lobes
 Frontal
 Parietal
 Occipital
 Temporal
FPOT
 Executive functioning
 Motor cortex
 Different areas control
different parts of body
 Prefrontal cortex
 Thinking, planning,
language
 Phineas Gage
 Broca’s area (language)
 Somatosensory cortex
 Perception
 Processing others’
actions
 Numbers
 Hearing, understanding
language, storing
memories
 Auditory cortex
 Hearing
 Wernicke’s area (also
part of parietal)
 Understanding speech
 Visual cortex
 Seeing
 Humans especially
dependent on vision
The Motor Cortex is the area at the rear of the
frontal lobes that control voluntary movements.
The Sensory Cortex (parietal cortex) receives
information from skin surface and sense organs.
More intelligent animals have increased “uncommitted” or
association areas of the cortex. These integrate sensory and
motor information. (75% of cerebral cortex)
Aphasia is an impairment of language, usually
caused by left hemisphere damage either to Broca’s
area (impaired speaking) or to Wernicke’s area
(impaired understanding).
Brain activity when hearing, seeing, and speaking
words
 Complex cable of nerves that connects brain to rest of the
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body
The spinal cord controls some protective reflex movements
without any input from the brain
Carries motor impulses from the brain to internal organs and
muscles
Carries sensory information from extremities and internal
organs to the brain
400,000 people a year in US either partial or complete
paralysis.
Brain Hemispheres Study
 Corpus Callosum (Video)
 Fibers that connect the two hemispheres
 Allow close communication between left
and right hemisphere
 Each hemisphere appears to specialize in
certain function
 The brain can be changed, both structurally and
chemically, by experience
 Rat studies show that an “enriched” environment leads
to larger neurons with more connections
 Has also been shown in humans
 Recent research has uncovered evidence of
neurogenesis, or the production of new brain cells, in
human brains
 Collateral Sprouting – Process where
healthy neurons will grow new branches
when near damaged cells.
 Substitution of Function – A damaged
region of brain is taken over by another area
 Neurogenesis – New neurons are generated
within the brain
 Rotate your dominant hand in one direction while at the
same time rotating the opposite foot in the other direction.
 No problem since controlled by two hemispheres
 Now, rotate your dominant hand in one direction while at the
same time rotating the foot on the same side in the other
direction.
Our brain is divided
into two
hemispheres.
The left hemisphere
processes reading,
writing, speaking,
mathematics, and
comprehension
skills. In the 1960s, it
was termed as the
dominant brain.
People with intact brains also show left-right
hemispheric differences in mental abilities.
A number of brain scan studies show normal individuals
engage their right brain when completing a perceptual
task and their left brain when carrying out a linguistic
task.
A procedure in which the two hemispheres of the
brain are isolated by cutting the connecting fibers
(mainly those of the corpus callosum) between them.
Corpus Callosum
With the corpus
callosum severed,
objects (apple)
presented in the
right visual field can
be named. Objects
(pencil) in the left
visual field cannot.
Is handedness inherited? Yes. Archival and
historic studies, as well as modern medical
studies, show that the right hand is preferred.
This suggests genes and/or prenatal factors
influence handedness.
The percentage of left-handed individuals decreases
sharply in samples of older people (Coren, 1993).
Being left handed is difficult in a right-handed
world.