This great Greek philosopher was the preeminent biologist of his day and he opined that the heart was the seat of the intellect.

•Who was he?

•Was he right?

Aristotle was WRONG (about this at least)

• We now attribute intellect ( as well a host of other functions) to the brain.– That grayish lump resting w/i the bony cranium

– NAME THE 8 BONES OF THE CRANIUM!

– Weighs about 1600g in ♂ and about 1400g in ♀– Has about 1012 neurons, each of which may receive

as many as 200,000 synapses – talk about integration!

– Although these numbers connote a high level of complexity, the CNS is actually quite orderly.

Gray and White Matter• Microscopically, the CNS

contains 2 neural elements:– Neuron cell bodies (clusters

are known as nuclei)– Nerve fibers (axons) in

bundles called tracts.

• Viewed macroscopically, CNS tissues can be distinguished by color:– Gray matter consists of

somata, dendrites, and unmyelinated axons.

– White matter consists primarily of myelinated axons.

Brain Regions

1. Cerebrum

2. Diencephalon

3. Brainstem

4. Cerebellum

Cerebellum

Cerebrum• The largest, most

conspicuous portion of the brain.

• 2 hemispheres connected by the corpus callosum.

• Has an outer cortex of gray matter surrounding an interior that is mostly white matter, except for a few small portions.

• The surface is marked by ridges called gyri separated by grooves called sulci.

• Deeper grooves called fissures separate large regions of the brain.– The median longitudinal fissure separates the cerebral hemispheres.– The transverse fissure separates the cerebral hemispheres from the

cerebellum below.

• Deep sulci divide each hemisphere into 5 lobes:– Frontal, Parietal, Temporal, Occipital, and Insula

Lobes of the

Cerebrum

• The central sulcus separates the frontal lobe from the parietal lobe.– Bordering the central sulcus are 2 important gyri, the precentral

gyrus and the postcentral gyrus.

• The occipital lobe is separated from the parietal lobe by the parieto-occipital sulcus.

• The lateral sulcus outlines the temporal lobe.– The insula is buried deep within the lateral sulcus.

Where’s the insula?

What’s this called?

What’s the name of this region

Cerebrum

• Each cerebral hemisphere is divided into 3 regions:1. Superficial cortex of

gray matter

2. Internal white matter

3. The basal nuclei – islands of gray matter found deep within the white matter

Cerebral Cortex

• Allows for sensation, voluntary movement, self-awareness, communication, recognition, and more.

• Gray matter! • 40% of brain mass, but

only 2-3 mm thick.• Each cerebral

hemisphere is concerned with the sensory and motor functions of the opposite side (a.k.a. contralateral side) of the body.

6-Layered cortex6-Layered cortexLayer I (Molecular)

Layer II (External Granular)

Layer III (External Pyramidal)—cortico-cortical fibers

Layer IV (Internal Granular)—thalamocortical fibers (VPL, VPM, LGN)

Layer V (Internal Pyramidal)—CS, CB, & corticostriatal fibers (Betz giant pyramidal

cells)

Layer VI (Multiform)—corticothalamic projection & association fibers

Layer I (Molecular)

Layer II (External Granular)

Layer III (External Pyramidal)—cortico-cortical fibers

Layer IV (Internal Granular)—thalamocortical fibers (VPL, VPM, LGN)

Layer V (Internal Pyramidal)—CS, CB, & corticostriatal fibers (Betz giant pyramidal

cells)

Layer VI (Multiform)—corticothalamic projection & association fibers

AFFERENT (Layer IV is big in Brodmann Area 3,1,2)

AFFERENT (Layer IV is big in Brodmann Area 3,1,2)

EFFERENT (Layer V is big in

Brodmann Area 4)

EFFERENT (Layer V is big in

Brodmann Area 4)

Frontal LobeThe frontal lobe is the area of the brain responsible for higher cognitive functions.

These include:

• Problem solving• Spontaneity• Memory• Language• Motivation• Judgment• Impulse control• Social and sexual behavior.

Temporal LobeThe temporal lobe plays a role in emotions, and is also responsible for smelling, tasting, perception, memory, understanding music, aggressiveness, and sexual behavior.

The temporal lobe also contains the language area of the brain.

Parietal LobeThe parietal lobe plays a role in our sensations of touch, smell, and taste. It also processes sensory and spatial awareness, and is a key component in eye-hand co-ordination and arm movement.

The parietal lobe also contains a specialized area called Wernicke’s area that is responsible for matching written words with the sound of spoken speech.

Occipital LobeThe occipital lobe is at the rear of the brain and controls vision and recognition.

Limbic LobeThe limbic lobe is located deep in the brain, and makes up the limbic system.

Injury MechanismsThe brain is a complex and delicate organ, and one that is vulnerable to injury from a variety of different traumas. These include:

Frontal Lobe Injury

Occipital Lobe Injury

Temporal Lobe Injury

Parietal lobe injury

Frontal Lobe Injury

Click image to play or pause video

The frontal lobe of the brain can be injured from direct impact on the front of the head.

Impairment of recent memory, inattentiveness, inability to concentrate, behavior disorders, difficulty in learning new information. Lack of inhibition (inappropriate social and/or sexual behavior). Emotional lability. "Flat" affect. Contralateral plegia, paresis. Expressive/motor aphasia.

Occipital Lobe Injury

Click image to play or pause video

Occipital lobe injuries occur from blows to the back of the head.

Primary Visual Cortex: loss of vision opposite field. Visual Association Cortex: loss of ability to recognize object seen in opposite field of vision, "flash of light", "stars". 

Temporal Lobe Injury

Click image to play or pause video

Hearing deficits. Agitation, irritability, childish behavior. Receptive/ sensory aphasia.

Kluver-Bucy syndrome

Parietal lobe injury

• Inability to discriminate between sensory stimuli. • Inability to locate and recognize parts of the body (Neglect). • Severe Injury: Inability to recognize self. • Disorientation of environment space.

• Inability to write.

Cerebral Cortex

• 3 types of functional areas:1. Motor Control voluntary

motor functions

2. Sensory Allow for conscious recognition of

stimuli

3. Association Integration

BRODMANN’S AREASBRODMANN’S AREAS

88

6644 3,1,23,1,2

17171818

19193939

4040

41,4241,4245,4445,44 2222

99

1010

1111

1212

34342828

5,75,7

BRODMANN’S AREASBRODMANN’S AREAS

88

6644 3,1,23,1,2

17171818

19193939

4040

41,4241,4245,4445,44 2222

99

1010

1111

1212

34342828

5,75,7

8 = Frontal Eye Field

6 = Premotor ctx 5,7 = somesthetic association (apraxia, dom. side)

4 = Primary motor ctx

3,1,2 = Primary somatosensory ctx

41,42 = Primary auditory ctx (Transverse gyrus of Heschl)

45,44 = Broca’s speech area

22 = Wernicke’s speech area (arcuate fasciculus connect to Broca’s )

40 = Supramarginal gyrus (Rt/Lt confusion, dyscalculia, understanding speech)

39 = Angular gyrus (dyslexia & dysgraphia)

BRODMANN’S AREASBRODMANN’S AREAS

88

6644 3,1,23,1,2

17171818

19193939

4040

41,4241,4245,4445,44 2222

99

1010

1111

1212

34342828

39, 40 = Inf parietal lobe (Gerstmann’s syndrome) on dominant side

a) Rt/Lt confusion

b) dyscalculia

c) finger agnosia

d) dyslexia & dysgraphia

e) lower quadrantanopia (visual radiations to cuneus)

Parietal lobe, non-dominant hemisphere (Sup or Inf parietal lobes)

a) contralateral sensory neglect & astereognosis

b) construction apraxia

c) lower quadrantanopia (visual radiations to cuneus)

9,10,11,12 = Prefrontal ctx

Post part of orbital gyrus = smell

Uncus = serves as part of primary olfactory ctx (medial temporal lobe)

34 = Primary olfactory ctx (medial temporal lobe—seizures can have smell aura)

5,75,7

Cortical Motor Areas

1. Primary Motor Cortex

2. Premotor Cortex

3. Broca’s Area

4. Frontal Eye Field

Primary motor cortex

Broca’s Area

Premotor cortex

Frontal Eye Field

Primary (Somatic) Motor Cortex

• Located in the precentral gyrus of each cerebral hemisphere.

• Contains large neurons (pyramidal cells) which project to SC neurons which eventually synapse on skeletal muscles – Allowing for voluntary

motor control.– These pathways are known

as the corticospinal tracts or pyramidal tracts.

Premotor Cortex• Located just anterior

to the primary motor cortex.

• Involved in learned or patterned skills.

• Involved in planning movements.

Broca’s Area

• Typically found in only one hemisphere (often the left), anterior to the inferior portion of the premotor cortex.

• Directs muscles of tongue, lips, and throat that are used in speech production.

• Involved in planning speech production and possibly planning other activities.

Frontal Eye Field

• Controls voluntary eye movements.

• Found in and anterior to the premotor cortex, superior to Broca’s area.

Sensory Areas

• Found in the parietal, occipital, and temporal lobes.

1. Primary somatosensory cortex2. Somatosensory association cortex3. Visual areas4. Auditory areas5. Olfactory cortex6. Gustatory cortex7. Vestibular cortex

Primary Somatosensory Cortex

• Found in the postcentral gyrus.

• Neurons in this cortical area receive info from sensory neurons in the skin and from proprioceptors which monitor joint position.

• Contralateral input.

Somatosensory Association Cortex

• Found posterior to the primary somatosensory cortex and is neurally tied to it.

• Synthesizes multiple sensory inputs to create a complete comprehension of the object being felt.

Primary Visual Cortex

• Found in the posterior and medial occipital lobe.

• Largest of the sensory cortices.

• Contralateral input.

Visual Association Area• Surrounds the primary visual

cortex.• Basically vision is the

sensation of bars of light on our retinal cells. The primary visual cortex tells which cells are being stimulated and how.

Auditory Cortex• Found in the superior

margin of the temporal lobe, next to the lateral sulcus.

• Sound waves excite cochlear receptors in the inner ear which send info to the auditory cortex.

• There is also an auditory association area which lets us interpret and remember sounds.

Olfactory Cortex

• Found in the frontal lobe just above the orbits.

• Receptors in the olfactory epithelium extend through the cribriform plate and are excited by the binding of oderants. They then send their info to the olfactory cortex.

• Very much involved in memory and emotion.

Gustatory and Vestibular Cortices

• Gustatory cortex is involved in taste and is in the parietal lobe just deep to the temporal lobe.

• Vestibular cortex is involved in balance and equilibrium and is in the posterior insula

Association Areas

• Allows for analysis of sensory input.

1. Prefrontal cortex

2. Language areas

3. General interpretation area

4. Visceral association area

Language Areas• Large area for language understanding and production surrounding the lateral sulcus in the left (language-dominant) hemisphere

• Includes:– Wernicke’s area

understanding oral/written words

– Broca’s area speech production

– Lateral prefrontal cortex language comprehension and complex word analysis

– Lateral and ventral temporal cortex integrates visual and auditory stimulate

General and Visceral Association Areas

• General area integrates multiple stimuli into a single cogent “understanding of the situation.”– Found on only one

hemisphere – typically left. – Contained by 3 lobes:

temporal, occipital, and parietal.

• Visceral association area is involved in perception of visceral sensations (such as disgust).– Located in insular cortex

Lateralization

• The fact that certain activities are the almost exclusive domain of one of the 2 hemispheres.

• In most people, the left hemisphere has a more control over language, math, and logic.

• While the right hemisphere is geared towards musical, artistic and other creative endeavors.

• Most individuals with left cerebral dominance are right-handed.

Cerebral White Matter

• 3 types of fibers:

1. Commissural – connect corresponding areas of the 2 hemispheres. Largest is the corpus callosum.

2. Association fibers – connect different parts of the same hemisphere

3. Projection fibers – fibers entering and leaving the cerebral hemispheres from/to lower structures

Prefrontal Cortex

• Anterior frontal lobes• Involved in analysis,

cognition, thinking, personality, conscience, & much more.

• Look at its evolution

• Areas: 9-12, 13,44-47 and 24.

Connections- Afferent

Functions

• Control of ANS• Control of higher intellectual activities• Control of personality

• Control of emotional affects • Control of behavior and social

consciousness• Responsible for the resting EEG

Prefrontal leucotomy in Man

• Flight of ideas

• Euphoria

• Impairment of memory

• Attention and concentration power is lost

• Lack of intellectual activity

• Emotional instability