Structure and Function of the brain

1. Brain Structure and Function

2. “If the human brain were so
simple that we could
understand it, we would be so
simple that we couldn’t”
-Emerson Pugh, The Biological Origin of Human
Values (1977)

3. Phineas Gage
• September 13th, 1848
• Phineas 25 years old
• Rutland & Burlington Railroad, Cavendish,
VT
• Paving the way for new RR tracks
• “Tamping Iron”
– 1.25in x 3ft

5. • Accident
Phineas Gage
– Quick Recovery
• Months later: “No longer Gage”
– Before: capable, efficient, best foreman, well-balanced
mind
– After: extravagant, anti-social, liar, grossly profane
• Stint with P.T Barnum
• Died 12 years later
• Video Clip 

6. Evolution of the Brain
Reptilian  Paleomammalian  Neomammalian

7. The Brain
• Brainstem
–responsible for
automatic survival
functions
• Medulla
–controls heartbeat
and breathing

8. hippocampus
BRAINSTEM  Heart
rate and breathing
CEREBELLUM
 Coordination
and balance
Parts of the Brain
amygdala
pituitary
THALAMUS
 Relays
messages

9. The Cerebellum
–helps coordinate
voluntary
movement and
balance

10. The Limbic System
• Hypothalamus, pituitary,
amygdala, and hippocampus
all deal with basic drives,
emotions, and memory
• Hypothalamus  Hunger,
thirst, body temperature,
pleasure; regulates pituitary
gland (hormones)
• Pituitary  “Master Gland”
– Stimulates other glands to
produce hormones
• Amygdala  Aggression (fight)
and fear (flight)
• Hippocampus  Memory
processing

11. The Limbic System
 Hypothalamus
 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

12. The Limbic System
 Pituitary Gland
 A pea-sized gland attached to the
hypothalamus by a thin stalk.
 Has two bulb-like lobes
 Secretes hormones that are used to control
other glands
 GH – stimulates cells to grow & produce proteins
 FSH – stimluates ovaries to produce eggs/testes to
produce sperm
 Prolactin – stimulates mammary glands to produce
milk

13. The Limbic System
• Amygdala
 two almond-shaped
neural
clusters that are
components of
the limbic system
and are linked to
emotion and fear

14. The Brain
• Thalamus
– the brain’s sensory
switchboard, located
on top of the
brainstem
– it directs messages to
the sensory receiving
areas in the cortex
and transmits replies
to the cerebellum and
medulla

15. The Cerebral Cortex
• Cerebral Cortex
–the body’s
ultimate control
and information
processing
center

16. The lobes of the cerebral hemispheres

17. The lobes of the cerebral hemispheres
Planning, decision
making speech
Sensory
Auditory
Vision

18. The Cerebral Cortex
• Frontal Lobes
– involved in speaking and
muscle movements and in
making plans and judgments
– the “executive”
• Parietal Lobes
– include the sensory cortex

19. The Cerebral Cortex
• Occipital Lobes
– include the visual areas, which
receive visual information from the
opposite visual field
• Temporal Lobes
– include the auditory areas, each of
which receives auditory information
primarily from the opposite ear

20. The Cerebral Cortex
• Frontal (Forehead to top)  Motor Cortex
• Parietal (Top to rear)  Sensory Cortex
• Occipital (Back)  Visual Cortex
• Temporal (Above ears)  Auditory Cortex

21. The Cerebral Cortex
 Aphasia
 impairment of language, usually caused by left
hemisphere damage either to Broca’s area
(impairing speaking) or to Wernicke’s area
(impairing understanding) –see clips
 Broca’s Area
 an area of the left 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

22. Language Areas
• Broca 
Expression
• Wernicke 
Comprehension
and reception
• Aphasias
LEFT HEMISPHERE

23. Paul Broca [1800s]
• Suggested localization

24. Techniques to examine functions
of the brain
1. Remove part of
the brain & see
what effect it has
on behavior
2. Examine
humans who have
suffered brain
damage

25. 3. Stimulate the
brain
4. Record
brain activity

27. Brain Lateralization

28. Our Divided Brains
• Corpus collosum –
large bundle of
neural fibers
(myelinated axons,
or white matter)
connecting the two
hemispheres

29. Hemispheric Specialization
LEFT
Symbolic thinking
(Language)
Detail
Literal meaning
RIGHT
Spatial perception
Overall picture
Context,
metaphor

30. Contra-lateral
division of labor
• Right hemisphere
controls left side of
body and visual field
• Left hemisphere
controls right side of
body and visual field

31. Split Brain Patients
• Epileptic patients had corpus callosum cut
to reduce seizures in the brain
• Lives largely unaffected, seizures reduced
• Affected abilities related to naming objects
in the left visual field

32. Brain Plasticity

33. Brain Plasticity
• The ability of the brain to
reorganize neural pathways
based on new experiences
• Persistent functional changes in
the brain represent new
knowledge
• Age dependent component
• Brain injuries

34. Environmental influences on
neuroplasticity
Impoverished environment
Enriched environment

35. Sensation and Perception

36. Sensation
• The process by which the central
nervous system receives input from
the environment via sensory neurons
• Bottom up processing
– Piece together information to build a more
complex system or a “bigger picture”

37. Perception
• The process by which the brain
interprets and organizes sensory
information
• Top-down processing
– Overview  details  more specific details
– “breaking it down”

38. The psychophysics of sensation
• Absolute threshold  the minimum
stimulation needed to detect a stimulus with
50% accuracy
• Subliminal stimulation  below the
absolute threshold for conscious awareness
–May affect behavior without conscious
awareness
• Sensory adaptation/habituation 
diminished sensitivity to an unchanging
stimulus

39. The five major senses
• Vision – electromagnetic
– Occipital lobe
• Hearing – mechanical
– Temporal lobe
• Touch – mechanical
– Sensory cortex
• Taste – chemical
– Gustatory insular cortex
• Smell – chemical
– Olfactory bulb
– Orbitofrontal cortex
– Vomeronasal organ?

40. The sixth sense
And the seventh…and eighth…and ninth…
• Vestibular  balance and motion
– Inner ear
• Proprioceptive  relative position of body
parts
– Parietal lobe
• Temperature  heat
– Thermoreceptors throughout the body, sensory cortex
• Nociception  pain
– Nociceptors throughout the body, sensory cortex

41. Thresholds of the five major senses

42. The Retina
The retina at the
back of the eye
is actually part
of the brain!
Rods –
brightness
Cones – color