The Human Brain Master Watermark Image:

“If the human brain were so simple that we could understand it, we would be so simple that we couldn’t” -Emerson Pugh, The Biological Origin of Human Values (1977)

Phineas Gage September 13 th, 1848 Phineas 25 years old Rutland & Burlington Railroad, Cavendish, VT Paving the way for new RR tracks “Tamping Iron” –1.25in x 3ft

Accident –Quick Recovery Months later: “No longer Gage” –Before: capable, efficient, best foreman, well-balanced mind –After: extravagant, anti-social, liar, grossly profane Stint with P.T Barnum Died 12 years later Watch Clip Phineas Gage

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: Frontal

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)? 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? Frontal

Evolution of the Brain Reptilian  Paleomammalian  Neomammalian

The Brain Brainstem –responsible for automatic survival functions Medulla –controls heartbeat and breathing

The Brain Pons -Involved with breathing and circulatory function -Involved in sleeps and dreams -Helps to maintain homeostasis -Homeostasis: how the body self-regulates

BRAINSTEM  Heart rate and breathing CEREBELLUM  Coordination and balance Parts of the Brain amygdala pituitary hippocampus THALAMUS  Relays messages

Reticular Formation Widespread connections Arousal of the brain as a whole Reticular activating system (RAS) Maintains consciousness and alertness Functions in sleep and arousal from sleep

The Cerebellum –helps coordinate voluntary movement and balance

The Limbic System Hypothalamus, pituitary, amygdala, and hippocampus all deal with basic drives, emotions, and memory Hippocampus  Memory processing Amygdala  Aggression (fight) and fear (flight) Hypothalamus  Hunger, thirst, body temperature, pleasure; regulates pituitary gland (hormones)

The Limbic System  Hypothalamus  neural structure lying below (hypo) the thalamus; directs several maintenance activities  eating  drinking  body temperature  helps govern the endocrine system via the pituitary gland  linked to emotion  (show video)

The Limbic System Show self stimulation clip

The Limbic System Amygdala –two almond-shaped neural clusters that are components of the limbic system and are linked to emotion and fear

Charles Whitman August 1 st, 1966

The Brain Thalamus –the brain’s sensory switchboard, located on top of the brainstem –it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla

The Cerebral Cortex Cerebral Cortex –the body’s ultimate control and information processing center

The lobes of the cerebral hemispheres

Planning, decision making speech Sensory Auditory Vision

The Cerebral Cortex Frontal Lobes –involved in speaking and muscle movements and in making plans and judgments –the “executive” Parietal Lobes –include the sensory cortex

The Cerebral Cortex Occipital Lobes –include the visual areas, which receive visual information from the opposite visual field Temporal Lobes –include the auditory areas, each of which receives auditory information primarily from the opposite ear

The Cerebral Cortex Frontal (Forehead to top)  Motor Cortex Parietal (Top to rear)  Sensory Cortex Occipital (Back)  Visual Cortex Temporal (Above ears)  Auditory Cortex

Motor/Sensory Cortex Contralateral Homunculus Unequal representation

Sensory Areas – Sensory Homunculus Figure 13.10

The Cerebral Cortex  Aphasia  impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding) –see clips  Broca’s Area  an area of the left frontal lobe that directs the muscle movements involved in speech  Wernicke’s Area  an area of the left temporal lobe involved in language comprehension and expression

Language Areas Broca  Expression Wernicke  Comprehensionan and reception Aphasias LEFT HEMISPHERE

Paul Broca [1800s] Suggested localization

Techniques to examine functions of the brain 1. Remove part of the brain & see what effect it has on behavior 2. Examine humans who have suffered brain damage

3. Stimulate the brain 4. Record brain activity

Brain Lateralization

Our Divided Brains Corpus collosum – large bundle of neural fibers (myelinated axons, or white matter) connecting the two hemispheres

Hemispheric Specialization LEFT Symbolic thinking (Language) Detail Literal meaning RIGHT Spatial perception Overall picture Context, metaphor

Contra-lateral division of labor Right hemisphere controls left side of body and visual field Left hemisphere controls right side of body and visual field

Part I: Lobes, the Cerebral Cortex, and Cortical Regions of the Brain

Objectives: Students will be able to describe the general structure of the Cerebrum and Cerebral Cortex. Students will be able to identify the Cerebrum, the Lobes of the Brain, the Cerebral Cortex, and its major regions/divisions. Students will be able to describe the primary functions of the Lobes and the 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 Cerebellum

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

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)

Longitudinal Fissure Transverse Fissure Sylvian/Lateral Fissure Central Sulcus Specific Sulci/Fissures:

Lobes of the Brain (4) Frontal Parietal Occipital Temporal * Note: Occasionally, the Insula is considered the fifth lobe. It is located deep to the Temporal Lobe.

Lobes of the Brain - Frontal The Frontal Lobe of the brain is located deep to the Frontal Bone of the skull. (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:

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 – 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)

Primary Motor Cortex/ Precentral Gyrus Broca’s Area Orbitofrontal Cortex Olfactory Bulb Modified from: Regions Investigation (Phineas Gage)

Lobes of the Brain - 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: - Senses and integrates sensation(s) - Spatial awareness and perception (Proprioception - Awareness of body/ body parts in space and in relation to each other) Modified from:

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 visuo-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:

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:

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.

Primary Visual Cortex Visual Association Area Regions Modified from:

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 play an integral role in the following functions: - Hearing - Organization/Comprehension of language - Information Retrieval (Memory and Memory Formation) Modified from:

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. 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 Regions Modified from:

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:

Click the Region to see its Name Korbinian Broadmann - Learn about the man who divided the Cerebral Cortex into 52 distinct regions: Modified from:

Lobes and Structures of the Brain B. A. C. D. E. F. G.

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

Cortical Regions A. B. C. D. E. F. G. H. I. J. K.

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)

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

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: 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.

Resources Images: Larson, Gary. The Far Side. Phineas Gage: education.nih.gov/nihHTML/ose/snapshots/multimedia/ritn/Gage/Broken_brain1.htmlhttp://science- education.nih.gov/nihHTML/ose/snapshots/multimedia/ritn/Gage/Broken_brain1.html

Split Brain Patients Epileptic patients had corpus callosum cut to reduce seizures in the brain Lives largely unaffected, seizures reduced Affected abilities related to naming objects in the left visual field

Brain Plasticity

The ability of the brain to reorganize neural pathways based on new experiences Persistent functional changes in the brain represent new knowledge Age dependent component Brain injuries

Environmental influences on neuroplasticity Impoverished environment Enriched environment

Sensation The process by which the central nervous system receives input from the environment via sensory neurons Bottom up processing

Perception The process by which the brain interprets and organizes sensory information Top-down processing

The psychophysics of sensation Absolute threshold  the minimum stimulation needed to detect a stimulus with 50% accuracy Subliminal stimulation  below the absolute threshold for conscious awareness –May affect behavior without conscious awareness Sensory adaptation/habituation  diminished sensitivity to an unchanging stimulus

The five major senses Vision – electromagnetic –Occipital lobe Hearing – mechanical –Temporal lobe Touch – mechanical –Sensory cortex Taste – chemical –Gustatory insular cortex Smell – chemical –Olfactory bulb –Orbitofrontal cortex –Vomeronasal organ?

The sixth sense Vestibular  balance and motion –Inner ear Proprioceptive  relative position of body parts –Parietal lobe Temperature  heat –Thermoreceptors throughout the body, sensory cortex Nociception  pain –Nociceptors throughout the body, sensory cortex And the seventh…and eighth…and ninth…

Thresholds of the five major senses

The Retina The retina at the back of the eye is actually part of the brain! Rods – brightness Cones – color

Types of Neuroimaging Structural –Magnetic resonance imaging –Computed tomography –Ultrasound Functional –Functional MRI –Positron emission tomography –Single photon emission computed tomography

Magnetic Resonance Imaging Excellent for clearly visualizing structures in soft tissues, such as the brain. Very commonly used in: –Diagnosis –Image-guided surgery and therapy By adjusting scanning settings, specific features can be detected. MRI images are 2D slices through the body at a specific location.

MRI Scanner

MRI Image Formation When the RF pulse is turned off, the hydrogen protons return to their natural alignment within the magnetic field. Energy is released. The coil detects this signal and sends it to a computer for processing. The signal consists of complex values which have real and imaginary components.

MRI Image Formation Magnitude information from signal Phase information from signal Fourier Transfor m

MRI Visualization A series of 2D MRI images can be combined together to form a 3D volume. This volume can then be used to generate realistic visualizations and models.

Computed Tomography (CT) Tomography –Imaging in sections, or slices. Computed –Geometric processing used to reconstruct an image. –Computerized algorithms

Computed Tomography (2) Uses X-rays –Dense tissue, like bone, blocks x-rays. –Gray matter weakens (attenuates) the x-rays. –Fluid attenuates even less. A computerized algorithm (filtered backprojection) reconstructs an image of each slice.

CT Image Formation X-ray detector X-ray X-ray tube

Computed Tomography

CT Image Formation Backprojectio n

fMRI Functional MRI – used to investigate brain function. Enables watching brain activity in vivo. Measures haemodynamic response. –Changes in oxygen content of the blood occur as the result of neuronal activity.

Interdisciplinary Nature of fMRI Physics –Hardware tools Electrophysiology –Neuronal behaviour Psychology –Cognitive psychology Statistics –Making sense of observations Neuroanatomy