Image from: http://www.wonderquest.com/images/2004-04-09-brain.jpg

Anatomy & Physiology

The Human Brain

Master Watermark Image: http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

Part I:

Lobes, the Cerebral Cortex, and Cortical Regions of the Brain

Cerebrum -The largest division of the brain. It is divided into two hemispheres, each of which is divided into four lobes.

Cerebrum

Cerebrum

Cerebellum

http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

Cerebral Cortex

Cerebral Cortex

Cerebral Cortex - The outermost layer of gray matter making up the superficial aspect of the cerebrum.

http://www.bioon.com/book/biology/whole/image/1/1-6.tif.jpg

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.

Gyri (ridge)

Fissure

(deep groove)

Sulci (groove)

http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

Longitudinal Fissure

Transverse Fissure

Sylvian/Lateral Fissure

Central Sulcus

http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg

http://www.dalbsoutss.eq.edu.au/Sheepbrains_Me/human_brain.gif

Specific Sulci/Fissures:

Left/Right Hemisphere Specialization

• Analytic thought
• Step by step process
• Logic
• Conclusions based upon a logical or consecutive order
• Language
• Using words to name/describe/define
• Math & Science
• Number use, awareness of time, symbols, facts & linear reasoning

• Holistic thought
• Seeing “big” picture before understanding details
• Intuition
• Insight based upon incomplete patterns or “hunches”
• Creativity
• Demonstrative with minimal word use, understanding relationships
• Art & Music
• Putting pieces together to form “wholes”

LEFT

RIGHT

Lesson Outline

Lobes of the Brain (4)

• Frontal
• Parietal
• Occipital
• Temporal

* Note: Occasionally, the Insula is considered the fifth lobe. It is located deep to the Lateral Sulcus of the Temporal Lobe.

http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg

Lobes of the Brain - Frontal

• The Frontal Lobe of the brain is located deep to the Frontal Bone of the skull. It is anterior to the Central Sulcus and bordered laterally by the Lateral Sulcus.

(Investigation: Phineas Gage)

• It plays an integral role in the following functions/actions:

• - Memory Formation

• - Emotions

• - Decision Making/Reasoning

• - Personality

Investigation (Phineas Gage)

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

Primary Motor Cortex/ Precentral Gyrus

Broca’s Area

Orbitofrontal Cortex

Olfactory Bulb

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

Regions

Investigation (Phineas Gage)

Frontal Lobe - Cortical Regions

• Orbitofrontal Cortex – Site of Frontal Lobotomies

• Primary Motor Cortex (Precentral Gyrus) – Cortical site involved with controlling movements of the body.

• Broca’s Area – MOTOR speech. Controls facial neurons, speech, and language comprehension. Located on Left Frontal Lobe.

• Broca’s Aphasia – Results in the ability to comprehend speech, but the decreased motor ability (or inability) to speak and form words.

• Olfactory Bulb - Cranial Nerve I, Responsible for sensation of Smell

• * Desired Effects:
• - Diminished Rage
• - Decreased Aggression
• - Poor Emotional Responses

* Possible Side Effects:

- Epilepsy

- Poor Emotional Responses

- Perseveration (Uncontrolled, repetitive actions, gestures, or words)

Lobes of the Brain - Parietal Lobe

• The Parietal Lobe of the brain is located deep to the Parietal Bone of the skull. It is posterior to Central Sulcus and superior to the Lateral Fissures.

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

- Senses and integrates cutaneous stimuli

• Spatial awareness and perception
• (Proprioception - Awareness of body/ body parts in space and in relation to each other)

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

Parietal Lobe - Cortical Regions

• Primary Somatosensory Cortex (Postcentral Gyrus) – Site involved with processing of tactile and proprioceptive information.

• Somatosensory Association Cortex - Assists with the integration and interpretation of sensations relative to body position and orientation in space. May assist with visual-motor coordination.

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

Primary Somatosensory Cortex/ Postcentral Gyrus

Primary Gustatory Cortex

Somatosensory Association Cortex

Regions

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

Lobes of the Brain – Occipital Lobe

• The Occipital Lobe of the Brain is located deep to the Occipital Bone of the Skull.

• Its primary function is the processing, integration, interpretation, etc. of VISION and visual stimuli.

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

Primary Visual Cortex

Visual Association Area

Regions

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

Occipital Lobe – Cortical Regions

• Primary Visual Cortex – This is the primary area of the brain responsible for sight -recognition of size, color, light, motion, dimensions, etc.

• Visual Association Area – Interprets information acquired through the primary visual cortex.

​

Lobes of the Brain – Temporal Lobe

• The Temporal Lobes are located on the sides of the brain, deep to the Temporal Bones of the skull. They are inferior to the Lateral Fissures.

• They play an integral role in the following functions:

• Hearing

• Organization/Comprehension of language

• Information Retrieval (Memory and Memory Formation)

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

Primary Auditory Cortex

Wernike’s 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

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)

• Wernicke’s Area – Language comprehension & word choice. 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.

• Arcuate Fasciculus - A white matter tract that connects Broca’s Area and Wernicke’s Area through the Temporal, Parietal and Frontal Lobes. Allows for coordinated, comprehensible speech. Damage may result in:

- Conduction Aphasia - Where auditory comprehension and speech articulation are preserved, but people find it difficult to repeat heard speech.

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

The apex of the Parietal, Occipital and Temporal lobes of the brain is responsible for complex thought processing.

Click the Region to see its Name

Korbinian Broadmann - Learn about the man who divided the Cerebral Cortex into 52 distinct regions: http://en.wikipedia.org/wiki/Korbinian_Brodmann

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

Lobes and Structures of the Brain

B.

A.

C.

D.

E.

F.

G.

http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

Lobes and Structures of the Brain

B.

A. (groove)

C. (groove)

D.

E.

F.

G.

B. Frontal Lobe

G. Parietal Lobe

F. Occipital Lobe

D. Temporal Lobe

A. Central Sulcus

(groove)

E. Transverse Fissure

C. Sylvian/Lateral Fissure

http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

Cortical Regions

A.

B.

C.

D.

E.

F.

G.

H.

I.

J.

K.

http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

Cortical Regions

A.

B.

C.

D.

E.

F.

G.

H.

I.

J.

K.

A. Primary Motor Cortex/ Precentral Gyrus

B. Broca’s Area

C. Orbitofrontal Cortex

K. Primary Somatosensory Cortex/ Postcentral Gyrus

I. Primary Gustatory Cortex

J. Somatosensory Association Cortex

G. Primary Visual Cortex

H. Visual Association Area

E. Primary Auditory Cortex

F. Wernike’s Area

D. Primary Olfactory Cortex (Deep)

http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif

Q: Assuming this comical situation was factually accurate, what Cortical Region of the brain would these doctors be stimulating?

Copyright: Gary Larson

Part II: The Brain Stem

Brainstem – connects the cerebrum and spinal cord.

• Most basic part of your brain.

​

• Controls functions essential to life (breathing, digesting, eliminating waste, sleeping, maintaining body temperature…)

​

• Maintains life without “thinking”

​

Return to brain parts

Parts of the Brainstem

• Diencephalon
• Thalamus: afferent impulses except smell
• Hypothalamus: maintenance of homeostasis via visceral function; links the endocrine and nervous system
• Epithalamus (Pineal Gland): circadian rhythms

• Optic tracts, infundibulum (pituitary gland)

Pituitary Gland

• Used to be called the “master” gland because so many of its hormones regulate other endocrine functions.
• Anterior pituitary: secretes hormones directly into the blood stream. The hypothalamus release inhibitory hormones.
• Anterior pituitary hormones: growth hormone (GH), insulin growth factors, prolactin (PRL), Follicle stimulating hormone (FSH), leutinizing hormone (LH), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), melanocyte-stimulating hormone (MSH), and endorphins
• Posterior pituitary: the two hormones released by the posterior pituitary are produced by the hypothalamus.
• Oxytocin and Antidiuretic hormone (ADH)

Diencephalon

Parts of the Brainstem (cont.)

• Limbic System – parts of the cerebral cortex connecting the thalamus, hypothalamus & deep nuclei

​

• Guides behavior such as fear, anger, pleasure and sorrow

Parts of the Brainstem (cont.)

• Midbrain – between diencephalon and pons, myelinated connection to the spinal cord.

​

• Reflex center: corticospinal tracts and motor pathways

Parts of the Brainstem (cont.)

• Pons – between midbrain and medulla
• ​
• “bridge”
• controls respiratory rate

Parts of the Brainstem (cont.)

• Medulla Oblongata: pons to foramen magnum
• Cardiac control
• Vasomotor (blood pressure)
• Respiratory – coughing, sneezing, swallowing and vomiting
• ​
• ​

Reticular Formation

• Nerves connecting the brain stem and the cerebellum
• Activation causes wakefulness
• Deactivation causes sleep/unconsciousness/ coma

Cerebellum

• Found at the at the back of your head under the cerebrum.

​

• Means “little brain”

​

• Responsible for movement, balance, reflex, coordination, posture.

​

• Often takes over learned activities-

Like riding a bike!

​

A: Primary Motor Cortex

* This graphic representation of the regions of the Primary Motor Cortex and Primary Sensory Cortex is one example of a HOMUNCULUS:

Homunculus

Q: What do you notice about the proportions depicted in the aforementioned homunculus?

Q: What is meant by depicting these body parts in such outrageous proportions?

A: They are not depicted in the same scale representative of the human body.

A: These outrageous proportions depict the cortical area devoted to each structure.

- Ex: Your hands require many intricate movements and sensations to function properly. This requires a great deal of cortical surface area to control these detailed actions. Your back is quite the opposite, requiring limited cortical area to carry out its actions and functions, or detect sensation.

Back-Hom.

* Note: Homunculus literally means “little person,” and may refer to one whose body shape is governed by the cortical area devoted to that body region.

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

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.

Learn more about Phineas Gage: http://en.wikipedia.org/wiki/Phineas_Gage

Frontal

http://www.sruweb.com/~walsh/gage5.jpg

Q: Recalling what you have just learned regarding the frontal lobe, what possible problems or abnormalities may Gage have presented with subsequent to this type of injury (remember the precise location of the rod through his brain)?

A: Gage’s 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 Gage’s 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 Gage’s 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

The Damage Caused by Concussion

Seizures

• 3 basic types

• Grand Mal
• Involves total body convulsions, aka “tonic-clonic”

​

• Petit Mal
• Involves isolated body part convulsion, aka “focal”

​

• Absence
• Patient becomes unresponsive, and has no memory
• of occurrence. Appears to be day-dreaming but cannot
• awake. Very rare.

​

What is a seizure?

1. Abnormal discharge of electrical impulses within the brain

2. Rather than smooth constant production of Action Potentials,

neurons fire without any regulation, causing disruption to

brain function at the biochemical level

• Seizures generally have 3 parts:
• Aura - period of warning, usually olfactory or visual
• Ictus - actual seizure period
• Postictal state - time where body “resets” itself

Causes of Seizures

Alcohol Poisoning

Drug Overdose/Reaction

Head Injury

Fever (especially in children)

Neurological Defect (usually genetic)

Sepsis (in brain)

Brain Tumor

Stroke

Epilepsy

Lesson Outline

Epilepsy - a seizure disorder in which reoccurring seizures are the main symptom caused by an abnormal discharge of electrical activity from the neurons in the cerebral cortex.

• In the US more than 4 million people have some form of

epilepsy (http:www.neurologychannel.com/seizures)

• Risk of epilepsy is greatest in early childhood and late

adulthood.

​

• Seizures have been found depicted as early as in cavepaintings!

​

• 4,000 year old writings depict epileptics as “possessed by demons”

​

• Julius Ceasar, King Charles II, Vincent Van Gogh and novelist

Dustoyevsky have all been reported as suffering from seizures!

​

​

Treatments for Epilepsy

• 3 major courses of treatment:
• Drugs
• Generally first line of attack because it is effective, relatively inexpensive, and safe
• Diet
• Ketogenic diet - lots of fat and almost no carbohydrates
• This diet drastically alters the way our bodies get energy from food - instead of making glucose, it makes ketones
• Surgery
• Commissurotomy

Commissurotomy

• For patients with frequent and violent epileptic seizures, surgically splitting the corpus callosum was the only relief - known as a “commissurotomy”
• Corpus callosum is a bundle of nerve fibers which serve to connect the right and left cerebral hemispheres

Corpus

callosum

Lesson Outline

pegasus.cc.ucf.edu/ ~Brainmd1/callosum.html

http://nobelprize.org/medicine

/educational/split-brain/background.html

Split - Brain Phenomenon

• Over 30 years ago studies of patients with a severed corpus callosum discovered some interesting side effects
• Roger Sperry & Michael Gazzaniga were in the forefront in utilizing these discoveries to determine significant ideas concerning brain function

Vision - Part 1

• Right side of your brain controls your Left body functions
• Left side of your brain controls your Right body functions

• Each eyeball is divided into 2 parts
• Right Visual Field
• Left Visual Field

• Right Hemisphere receives visual info from LVF only
• Left Hemisphere receives visual info from RVF only

​

Vision - Part 2

• Left Visual Field is illustrated in RED
• Right Visual Field is illustrated in BLUE

​

Lesson Outline

Split-Brain Discoveries

• "The Man with 2 Brains” (click on play video)

Split-Brain Discoveries

• Ability to speak resides almost exclusively in Left Hemisphere (word recognition)
• Ability to recognize faces resides almost exclusively in Right Hemisphere (Archimbaldo paintings)
• “Don’t leave home without your left hemisphere!” - Michael Gazzaniga
• “The great pleasure and feeling in my right brain is more than my left brain can find the words to tell you.” - Roger Sperry

Lesson Outline

Vision Diagram

Sleep

If you spend on average 8 hours a day sleeping, how much of one year do you sleep away? If we “waste” this much time sleeping there MUST be some value for our bodies.

It seems as if we are not doing ANYTHING while we sleep, however if we take a close look at our brains we will find that our brains are very active while our bodies sleep. Examine the graphs below, notice how active our brain is when we are asleep compared with awake!

Scientists still are not sure why we sleep but there are two theories.

Resources

Images:

• http://www.dalbsoutss.eq.edu.au/Sheepbrains_Me/human_brain.gif
• http://www.bioon.com/book/biology/whole/image/1/1-8.tif.jpg
• http://www.bioon.com/book/biology/whole/image/1/1-6.tif.jpg
• http://williamcalvin.com/BrainForAllSeasons/img/bonoboLH-humanLH-viaTWD.gif
• http://www.math.tu-dresden.de/~belov/brain/motorcor2.gif
• Larson, Gary. The Far Side.

​

Phineas Gage:

• http://www.sruweb.com/~walsh/gage5.jpg
• http://soma.npa.uiuc.edu/courses/bio303/Image7.jpg
• http://en.wikipedia.org/wiki/Phineas_Gage
• http://science-education.nih.gov/nihHTML/ose/snapshots/multimedia/ritn/Gage/Broken_brain1.html