2. Cerebrum –“seat of intelligence”
The largest division of the brain. It is divided into two
hemispheres, each of which is divided into four lobes.
Cerebrum
Cerebrum
Cerebellum
3. Cerebrum
“seat of intelligence.”
It provides us with the ability to
Read-write, and speak
To make calculations and compose
music;
To remember the past, plan for the
future, and imagine things that have never
existed before
5. Physiological anatomy
The functional part of the cerebral
cortex is a thin layer of neurons
covering the cerebrum.
About 2-5mm thick and contains
100 billion neurons.
6. Lobes of the Brain (4)
1. Frontal
2. Parietal
3. Occipital
4. Temporal
7. Ridges called Gyri (gyrus)
Shallow grooves called Sulci
(sulcus)
Deeper grooves called Fissures
10. Cerebral Hemispheres - Lobes
Central sulcus – separates the frontal and parietal
lobes
Parieto-occipital sulcus – separates the parietal and
occipital lobes
Lateral sulcus – separates the parietal and temporal
lobes
11.
12. Cerebral Features:
• Sulci – Small grooves dividing the gyri
– Central Sulcus – Divides the Frontal Lobe from the Parietal Lobe
• Fissures – Deep grooves, generally dividing large regions/lobes of the brain
– Longitudinal Fissure – Divides the two Cerebral Hemispheres
– Transverse Fissure – Separates the Cerebrum from the Cerebellum
– Sylvian/Lateral Fissure – Divides the Temporal Lobe from the Frontal
and Parietal Lobes
• Gyri – Elevated ridges “winding” around the brain.
13. Cerebral Hemispheres – 3 basic regions
I. Cortex– superficial gray matter, 1-4.5 mm thick
II. White matter– inner, unmyelinated
III. Basal Nuclei– islands of gray matter within the white matter
Cortex (40% of brain mass) consists of neuron cell bodies,
dendrites, and unmyelinated axons (plus glial cells and blood
vessels)
14. Cerebral Cortex
Enables sensation, communication, memory,
understanding, and voluntary movements
Each hemisphere controls the opposite (contralateral)
side of the body
Hemispheres are not functionally equivalent
No functional area acts alone - conscious behavior
involves the entire cortex
15. Precentral gyrus—located
immediately anterior to the
central sulcus— contains the
primary motor area of the
cerebral cortex
The postcentral gyrus,
which is located immediately
posterior to the central
sulcus, contains the primary
somatosensory area of the
cerebral cortex.
16. Cerebral Cortex
Three kinds of functional areas:
Motor areas – control voluntary movement
Sensory areas – conscious awareness of
sensation
Association areas – integrate diverse
information, communicate “associate” with the
motor cortex and sensory association areas to
analyze input
20. Introduction
Most Voluntary movements initiated in the Cerebral Cortex
are achieved when the cortex activates “ patterns” of
functions stored in the lower brain areas--- the cord, brain
stem, basal ganglia, and the cerebellum.
These centers send specific control signals to specific
muscles.
21. Functional Organization of the Cerebral Cortex
Sensory areas
Receive sensory information and are involved in
perception, the conscious awareness of a
sensation
Motor areas
Control the execution of voluntary movements;
Association areas
Deal with more complex integrative functions
such as memory, emotions, reasoning, will,
judgment, personality traits, and intelligence.
22. Motor Cortex
The area of the brain which is responsible to control
the motor activity is “Motor Cortex”.
posterior one-third of the frontal lobe.
It is divided into
1. The primary motor cortex
2. The premotor area
3. The supplementary motor area.
23. Primary Motor Cortex
Located in the precentral gyrus of the frontal lobe
Allows conscious control of voluntary movements
Composed of neurons called pyramidal cells-axons
project to the spinal cord and make up the
voluntary motor tracts called corticospinal tracts
28. 1. Primary Motor Cortex
Responsible for coordination of hands and distal muscles.
The body is represented upside down.
Area occupied depends upon the complexity of activity and
not on the size of the effector organ. (See Cortical
Homunculus)
Each region within the area controls voluntary contractions of
specific muscles or groups of muscles
Electrical stimulation of any point in the primary motor area
causes contraction of specific skeletal muscle fibers on the
opposite side of the body
29. 2. Supplementary MotorArea
Contractions elicited by stimulating this area are
often bilateral rather than unilateral.
SMA includes the stabilization of the body posture.
Example
the coordination of both sides of the body such as
during bimanual action, the control of movements
that are internally generated rather than triggered by
sensory events, and the control of sequences of
movements
30. 3. PremotorArea
It is very important for complex Movements (imaginary
movements)
The premotor area deals with learned motor activities of a
complex and sequential nature.
It generates nerve impulses that cause specific groups of
muscles to contract in a specific sequence, as when you write
your name.
The premotor area also serves as a memory bank for such
movements.
Example: to position shoulders and arms so that hands are
properly oriented to perform specific tasks.
Mirror neurons are present in this area.
A mirror neuron is a neuron that fires both when an animal
acts and when the animal observes the same action performed
by another
32. Some SpecializedAreas Of Motor
Control
1. Broca’s area
2. “Voluntary” Eye movement field
3. Head rotation area
4. Area for hand skills
33. 1. Broca’s area
Located anterior to
the inferior region
of the premotor area
Present in one
hemisphere (usually
the left)
A motor speech
area that directs
muscles involved in
speech
Is active as one
prepares to speak
34. 2. “Voluntary” Eye movement field
Located anterior to the premotor cortex and superior to
Broca’s area
Controls voluntary eye movement
It controls voluntary scanning movements of the eyes—
like those you just used in reading this sentence
This frontal area also controls eyelid movements such as
blinking
35. 3. Head rotation area
Slightly higher in the motor association area, electrical
stimulation elicits head rotation.
This area is closely associated with the eye movement field; it
directs the head toward different objects.
36. 4.Area for hand skills
In the premotor area immediately anterior to the primary motor
cortex for the hands and fingers is a region neurosurgeons have
identified as important for “hand skills.”
That is, when tumors or other lesions cause destruction in this
area, hand movements become uncoordinated and
nonpurposeful, a condition called motor apraxia.
37. Prefrontal Cortex
Located in the anterior portion of the frontal lobe
Involved with intellect, cognition, recall, personality,
judgment, reasoning, and conscience
Closely linked to the limbic system (emotional part of
the brain)
39. SensoryAreas
Information arrives in posterior half of both cerebral
hemisphere.
In cerebral cotex primary sensory area receive
information that has been relayed from peripheral sensory
receptors.
i. Primary somatosensory cortex
ii. Somatosensory association cortex
iii. Visual and auditory areas
iv. Olfactory, gustatory, and vestibular cortices
41. Structurally distinctareas,called Brodmann’s areas,of
thehuman cerebral cortex. Notespecifically areas 1,2,and 3,which
constituteprimary somatosensory area I,and areas5and 7A,which
constitutethesomatosensory association area.
Figure is a map of the
human cerebral cortex,
showing
that it is divided into
about 50 distinct areas
called
Brodmann’s areas
based on histological
structural differences.
This map is important
because virtually all
neurophysiologists and
neurologists use it to
refer to many of the
different functional areas
of the human cortex by
number
42. 1. Primary Somatosensory Cortex
(SomatosensoryArea I)
Located in the postcentral gyrus of the parietal lobe
Receives information from somatic sensory receptors in the
skin and proprioceptors in skeletal muscles
Exhibits spatial discrimination
The primary visual area
The primary auditory area
The primary gustatory area
The primary olfactory area
44. Somatic sensory and somatic motor maps in the cerebral cortex, right hemisphere. (a) Primary somatosensory
area (postcentral gyrus) and (b) primary motor area (precentral gyrus) of the right cerebral hemisphere. The left
hemisphere has similar representation0n
45. 2. SomatosensoryAssociation Cortex
(SomatosensoryArea II)
Located posterior to the primary somatosensory
cortex
Integrates sensory information coming from the
primary somatosensory cortex to produce an
understanding (size, texture, and relationship of
parts) of the stimulus
The somatosensory association area allows you to
recognize objects such as a pencil and a paperclip
simply by touching them
46. VisualAreas
Primary visual (striate) cortex - located on the
posterior tip of the occipital lobe, most of it is buried
in the calcarine sulcus - receives visual information
from the retinas
Visual association area - surrounds the primary visual
cortex - interprets visual stimuli (e.g., color, form, and
movement)
47. AuditoryAreas
Primary auditory cortex - located in the superior
margin of the temporal lobe -receives information
related to pitch, rhythm, and loudness
Auditory association area - located posterior to the
primary auditory cortex -stores memories of sounds
and permits perception of sounds
48. OtherAreas
Olfactory (smell) cortex – small area of frontal lobe
above the orbit and in medial temporal lobe. Receive
impulses for smell
Gustatory (taste) cortex – in parietal lobe deep to
temporal lobe. Receive impulses for taste.
49. Wernicke’s area
Posterior language area
Interprets the meaning of speech by recognizing
spoken words.
It is active as you translate words into thoughts.
50. Lateralization of Cortical Function
Lateralization – each hemisphere has abilities not
shared with the other hemisphere
Cerebral dominance – designates the hemisphere
dominant for language
Left hemisphere – controls language, math, and logic
Right hemisphere – controls visual-spatial skills,
emotion, and artistic skills
