The Human Brain

1
The Human Brain
2

• Cerebrum -The largest division of the brain.
• Divided into two hemispheres and quartered into
  lobes

http//williamcalvin.com/BrainForAllSeasons/img/bo
noboLH-humanLH-viaTWD.gif
3
Cerebral Cortex - The outermost layer of gray
matter making up cerebrum.
http//www.bioon.com/book/biology/whole/image/1/1-
6.tif.jpg
4

• Cerebral Features

• Gyri Elevated ridges winding around the
  brain.

• Sulci Small grooves dividing the gyri

• Central Sulcus Divides the Frontal Lobe from
  the Parietal Lobe

• Fissures Deep grooves divide large regions of
  the brain

• Longitudinal Fissure Divides the two Cerebral
  Hemispheres

• Transverse Fissure Separates the Cerebrum from
  the Cerebellum

• Sylvian Fissure Divides the Temporal Lobe from
  the Frontal and Parietal Lobes

5
Lobes of the Brain (4)

• Frontal
• Parietal
• Occipital
• Temporal

http//www.bioon.com/book/biology/whole/image/1/1-
8.tif.jpg
6
Frontal Lobe
It plays an integral role in the following
functions
- Memory Formation
- Emotions
- Decision Making/Reasoning
- Personality
(Investigation Phineas Gage)
Investigation (Phineas Gage)
Modified from http//www.bioon.com/book/biolog
y/whole/image/1/1-8.tif.jpg
7
Frontal Lobe

• Primary Motor Cortex Controls movements of the
  body.

• Brocas Area Controls facial neurons, speech,
  and language comprehension. Located on Left
  Frontal Lobe.

• Olfactory Bulb - Responsible for sensation of
  Smell

8
Investigation (Phineas Gage)
Primary Motor Cortex
Brocas Area
Olfactory Bulb
Regions
Modified from http//www.bioon.com/book/biology
/whole/image/1/1-8.tif.jpg
9
Lobotomies

• Desired Effects
• - Diminished Rage
• Decreased Aggression
• Improved mood

• Possible Side Effects
• - Epilepsy
• - Poor Emotional Responses
• Uncontrolled, repetitive actions, gestures, or
  words
• Death

10
Parietal Lobe

• The Parietal Lobe of the brain is located deep to
  the Parietal Bone of the skull.

• It plays a major role in the following
  functions/actions

• Cognition
• Information Processing
• Pain and Touch Sensation
• Spatial Orientation
• Speech
• Visual Perception (Proprioception)

Modified from http//www.bioon.com/book/biology
/whole/image/1/1-8.tif.jpg
11
Parietal Lobe

• Somatosensory Cortex Processes sensory
  information about touch, location of limbs, pain
  and temperature.

• Gustatory Cortex Primary site involved with
  the interpretation of the sensation of Taste.

Sensory Homunculus
12
Primary Somatosensory Cortex
Primary Gustatory Cortex
Modified from http//www.bioon.com/book/biology
/whole/image/1/1-8.tif.jpg
Regions
13
Occipital Lobe

• Located at the very back of the brain.

• Primary function processing of visual
  information. (seeing colors, as well as
  perceiving and recognizing objects)

Modified from http//www.bioon.com/book/biology
/whole/image/1/1-8.tif.jpg
14
Occipital Lobe

• Primary Visual Cortex (PVC) Receives electrical
  signals from receptors in the eyes and transforms
  these signals into meaningless basic visual
  sensations. (lights, lines, shadows, colors,
  textures)

• Visual Association Area located next to PVC.
  Transforms basic sensations into visual
  perceptions such as a person, object, or animal.

15
Neglect Syndrome The failure of a patient to see
objects or parts of the body on the side
Opposite the brain damage.
16
Primary Visual Cortex
Visual Association Area
Regions
Modified from http//www.bioon.com/book/biology
/whole/image/1/1-8.tif.jpg
17
Temporal Lobe

• The Temporal Lobes are located on the sides of
  the brain, below the Parietal Lobe

• They play an integral role in the following
  functions

• Hearing
• Speaking coherently
• Ability to understand verbal and written
  material.
• Memory (hippocampus)

Modified from http//www.bioon.com/book/biology
/whole/image/1/1-8.tif.jpg
18
Arcuate Fasciculus - White matter tract that
connects Brocas Area and Wernickes Area.
Allows for coordinated, comprehensible speech.
Damage may result in
Conduction Aphasia - Where auditory comprehension
and speech articulation are preserved, but speech
repetition is affected.
19
Temporal Lobe Cortical Regions

• Primary Auditory Cortex Responsible for hearing

• Primary Olfactory Cortex Interprets the sense
  of smell once it reaches the cortex via the
  olfactory bulbs. (Not visible on the superficial
  cortex)

• Wernickes Area Language comprehension.
  Located on the Left Temporal Lobe.

Wernickes Aphasia Language comprehension is
inhibited. Words and sentences are not clearly
understood, and sentence formation may be
inhibited or nonsensical.
20
Temporal Lobe

• Hippocampus Formation of new episodic memories
  
• and the retrieval of old memories.
• Damage to Hippocampus does not affect ability
  to learn
• new skills only to form memories. (procedural
  vs. autobiographic)

21
Primary Auditory Cortex
Wernikes Area
Primary Olfactory Cortex (Deep) Conducted from
Olfactory Bulb
Regions
Modified from http//www.bioon.com/book/biology
/whole/image/1/1-8.tif.jpg
22
Lobes and Structures of the Brain
A. Central Sulcus
B. Frontal LOBE
C. Sylvian/Lateral Fissure
A. (groove)
G.
D. Temporal Lobe
B.
F.
E. Transverse Fissure
F. Occipital Lobe
C. (groove)
G. Parietal Lobe
E.
D.
(groove)
http//williamcalvin.com/BrainForAllSeasons/img/bo
noboLH-humanLH-viaTWD.gif
23
Further Investigation
Phineas Gage Phineas Gage was a railroad worker
in the 19th century living in Cavendish, Vermont.
One of his jobs was to set off explosive charges
in large rock in order to break them into smaller
pieces. On one of these instances, the
detonation occurred prior to his expectations,
resulting in a 42 inch long, 1.2 inch wide, metal
rod to be blown right up through his skull and
out the top. The rod entered his skull below his
left cheek bone and exited after passing through
the anterior frontal lobe of his brain.
Frontal
24
Remarkably, Gage never lost consciousness, or
quickly regained it (there is still some debate),
suffered little to no pain, and was awake and
alert when he reached a doctor approximately 45
minutes later. He had a normal pulse and normal
vision, and following a short period of rest,
returned to work several days later. However, he
was not unaffected by this accident.
Frontal
25
Q Recalling what you have just learned
regarding the frontal lobe, what possible
problems or abnormalities may Gage have presented
subsequent to this type of injury (remember the
precise location of the rod through his brain)?
A Gages personality, reasoning, and capacity
to understand and follow social norms had been
diminished or destroyed. He illustrated little to
no interest in hobbies or other involvements that
at one time he cared for greatly. After the
accident, Gage became a nasty, vulgar,
irresponsible vagrant. His former employer, who
regarded him as "the most efficient and capable
foreman in their employ previous to his injury,"
refused to rehire him because he was so
different.
Q It is suggested that Gages injury inspired
the development of what at one time was a widely
used medical procedure. What might this
procedure be, and how does it relate to Gages
injury?
A The frontal lobotomy. This has been used
with the intention to diminish aggression and
rage in mental patients, but generally results in
drastic personality changes, and an inability to
relate socially. This procedure is largely
frowned upon today, with the development of
neurological drugs as treatments.
Frontal
26
Whats in your brain?
Approximately 1 trillion cells.
(1,000,000,000,000)
27
Glial Cells

• Most numerous brain cell (900 billion)
• Three Functions
• Scaffolding to guide the growth of new neurons /
  support mature neurons
• Insulation to prevent interference from other
  electrical signals.
• Release chemicals that influence a neurons
  growth and function.

28
The Neuron
The Fax Machine of the Human Body
Has two specialized extensions, one for
receiving and the other is for transmitting
electrical signals.
29
DENDRITES

• Receive information from other neurons, organs
  and muscles.
• Bring information TO the cell body

30
AXONS

• Axons Send information AWAY from the cell body
  to neighboring neurons, organs, or muscles.
• Axon terminals - the hair-like ends of the axon
  that store neurotransmitters

31
The Neuron                                      
                 
32
Parts of a Neuron
Myelin sheath - the fatty substance that
surrounds and protects nerve fibers Node of
Ranvier - one of the many gaps in the myelin
sheath Schwann's cells - cells that produce
myelin
33
(No Transcript)