The Human Brain
www.outreach.mcb.harvard.edu/teachers/Summer05/EthanBlanchette
Master Watermark Image:
http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
A) Overview of Brain Functions
• Sensory (auditory, visual, olfactory, touch,
taste, pain)
• motor control & coordination of skeletal
muscles
• regulation of visceral activities &
homeostasis
• higher mental activities (intellect,
memory, language, decision-making)
• emotional processing (feelings,
personality)
“How Neurosurgeons Learn the Functions of the Brain”
Copyright: Gary Larson
B) Major parts of the brain
1. cerebrum
2. diencephalon (thalamus,
hypothalamus, epithalamus and
encloses the third ventricle)
3. brain stem (midbrain, pons, medulla
oblongata)
4. cerebellum
Cerebrum
Cerebrum
Cerebellum
Phineas Gage 1848
C) Overview of the Cerebrum
a) This is the largest division of the brain, and
is divided into left & right hemispheres.
LEFT
RIGHT
• The cerebrum shows lateralization of function:
– The two sides of the brain are joined inferiorly by
the corpus callosum which communicates
information from one side to the other.
– Right hemisphere controls the left side of the body
(motor control) and vice versa.
– For most people the left hemisphere is dominant
and is specialized for language and math
– The right hemisphere is specialized for visualspatial skills and creativity
b) The outermost layer of gray matter makes up
the superficial aspect of the cerebrum.
Cerebral Cortex
Cerebral
Cortex
c) Structural features
(1) gyrus (gyri) – elevated ridge
“winding” around the brain.
(2) sulcus (sulci) –shallow groove
dividing the cerebrum into lobes
• central sulcus – divides the
frontal lobe from the parietal
lobe
(3) fissure – deep groove, generally
dividing large regions/lobes of the brain
• Longitudinal Fissure – Divides
the left & right cerebral
hemispheres
• Transverse Fissure – Separates
the cerebrum from the cerebellum
• Sylvian/Lateral Fissure –
Divides the temporal lobe from
the frontal and parietal Lobes
Vocabulary Practice:
Table partners:
Identify the following
features of the brain
Gyrus (ridge)
1
Sulcus
(shallow
3 groove)
Fissure 2
(deep groove)
Central Sulcus
4
5
Sylvian/Lateral Fissure
Sulci/Fissures
Longitudinal Fissure
7
6
Transverse Fissure
d) Each hemisphere is divided into 4 lobes.
2
1
3
4
e) Functional regions of the Cerebral
cortex
- Sensory areas
- Association areas
- Motor areas
D) Lobes of the Cerebrum
Frontal lobe Functions
- Memory Formation
- Emotions
- Decision Making/Reasoning
- Problem solving
- Personality
Frontal lobe areas
•Primary Motor Cortex (Precentral Gyrus) –
controls movements of the body
•Premotor cortex—guides eye & head movements,
and a person’s sense of orientation
•Prefrontal cortex—controls memory, intelligence,
concentration, temper, personality
•Broca’s area—controls language production
(located in left frontal lobe)
•Olfactory bulb—is responsible for sense of smell
(located inferiorly, leads to cranial nerve I)
Parietal Lobe
• Somatosensory Association Cortex:
senses and integrates sensations relative
to body position and orientation in space
• Primary Somatosensory Cortex
(Postcentral Gyrus) –Spatial awareness
and perception; proprioception
(awareness of body/ body parts in space
and in relation to each other)
• Primary Gustatory Cortex –
interpretation of the sensation of taste.
Primary
Somatosensory
Cortex/
Postcentral Gyrus
Somatosensory
Association Cortex
Primary
Gustatory Cortex
Occipital Lobe
• Primary Visual Cortex –responsible for sight
-recognition of size, color, light, motion,
dimensions
• Visual Association Area – Interprets
information acquired through the primary visual
cortex.
Primary Visual
Cortex
Visual
Association Area
Temporal Lobe
• 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)
• Wernicke’s Area – responsible for language
comprehension; located on the left temporal lobe
Wernicke’s Aphasia – Language comprehension is
inhibited. Words and sentences are not clearly
understood, and sentence formation may be
inhibited or non-sensical.
Primary
Auditory Cortex
Wernike’s Area
Primary Olfactory
Cortex (Deep)
Conducted from Olfactory Bulb
Lobes of the Brain
A.
B.
E.
C.
D.
Homunculus: Primary Motor Cortex & Sensory Cortex
Homunculus: Primary Motor Cortex
E) diencephalon
1. Thalamus-relay station for sensory and
motor impulses to & from the cerebrum
2. Hypothalamus-regulates pituitary gland,
body temp, food intake, water balance,
thirst, and sleep-wake cycles
3. Limbic System- mediates emotional
responses and memory
e.g. “smell memories,” psychosomatic
illness, sense of pleasure
F) brain stem
10 of the
12 pairs
of cranial
nerves
1. midbrain- visual and auditory
reflex centers e.g tracking
2. pons- rate & depth of
respiration
3. medulla oblongata- respiratory
rhythm, heart rate, and blood
pressure
*contains decussation of pyramids
(crossover point)
G) cerebellum
• white matter is branched = arbor vitae
• processes and interprets input from the
frontal motor cortex for posture,
balance, and smooth movements