15 lecture 8 brain structure sl .1

7/28/2019 15 Lecture 8 Brain Structure Sl .1

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If the human brain were sosimple that we could

understand it, we would be sosimple that we couldnt

-Emerson Pugh, The Biological Origin of HumanValues (1977)


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September 13th, 1848

Phineas 25 years old

Rutland & Burlington Railroad, Cavendish, VT Paving the way for new RR tracks

Tamping Iron

1.25in x 3ft


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The skull is a rounded layer of

bone designed to protect the brain

from penetrating injuries.

Blood Vessels of the Skull

Rough Interior of Skull


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The base of the skull is rough,with many bony protuberances.

These ridges can result in injury

to the temporal lobe of the brain

during rapid acceleration.

Bony ridges

Injury from contact

with skull


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Accident Quick Recovery

Months later: No longer Gage

Before: capable, efficient, best foreman, well-balancedmind

After: extravagant, anti-social, liar, grossly profane

Stint with P.T Barnum

Died 12 years later

Watch Clip


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Reptilian PaleomammalianNeomammalian


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Brainstem

responsible for

automatic survivalfunctions

Medulla

controls heartbeatand breathing


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BRAINSTEM Heartrate and breathing

CEREBELLUM

Coordination

and balance

amygdala

pituitary

hippocampusTHALAMUS

Relaysmessages


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Widespreadconnections

Arousal of the brain

as a wholeReticular activating

system (RAS)

Maintainsconsciousness and

alertness

Functions in sleep


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helps coordinate

voluntarymovement andbalance


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Hypothalamus, pituitary,amygdala, andhippocampus all deal withbasic drives, emotions, andmemory

Hippocampus Memoryprocessing

Amygdala Aggression

(fight) and fear (flight)

Hypothalamus Hunger,thirst, body temperature,pleasure; regulates

pituitary gland (hormones)


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Hypothalamus neural structure lying below

(hypo) the thalamus; directsseveral maintenanceactivities eating

drinking

body temperature

helps govern the endocrine

system via the pituitarygland

linked to emotion

(show video)


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Show self stimulation clip


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Amygdala

two almond-

shaped neuralclusters that arecomponents of

the limbicsystem and arelinked to

emotion and fear


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CharlesWhitman

August 1st, 1966


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Thalamus the brains sensory

switchboard, locatedon top of the

brainstem

it directs messages tothe sensory receiving

areas in the cortexand transmits repliesto the cerebellumand medulla


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Cerebral Cortex

the bodys

ultimate controland informationprocessing

center


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Planning, decisionmaking speech

Sensory

AuditoryVision


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Parietal Lobe

Temporal Lobe

Frontal Lobe

Limbic Lobe

Occipital Lobe


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The frontal lobe is the area ofthe brain responsible for

higher cognitive functions.

These include:

Problem solving

Spontaneity Memory

Language

Motivation

Judgment

Impulse control

Social and sexual behavior.


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The temporal lobe plays arole in emotions, and is

also responsible for

smelling, tasting,

perception, memory,

understanding music,

aggressiveness, andsexual behavior.

The temporal lobe also

contains the language

area of the brain.


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The 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-ordinationand arm movement.

The parietal lobe also

contains a specialized

area called Wernickes

area that is responsible

for matching writtenwords with the sound of

spoken speech.


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The occipital lobe is atthe rear of the brain

and controls vision

and recognition.


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The limbic lobe islocated deep in the

brain, and makes up

the limbic system.


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A. Cingulate gyrus

B. Fornix

C. Anterior thalamic

nuclei

D. Hypothalamus

E. Amygdaloid nucleus

F. Hippocampus

The limbic system is thearea of the brain that

regulates emotion and

memory. It directly

connects the lower and

higher brain functions.


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The cerebellum is connected to thebrainstem, and is the center for

body movement and balance.

Click image to play or pause video


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Thalamus means inner room in Greek,

as it sits deep in the brain at the top ofthe brainstem.

The thalamus is called the gateway to

the cerebral cortex, as nearly all

sensory inputs pass through it to the

higher levels of the brain.


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The hypothalamus sits under the thalamus atthe top of the brainstem. Although the

hypothalamus is small, it controls many critical

bodily functions:

Controls autonomic nervous system

Center for emotional response and behavior

Regulates body temperature

Regulates food intake

Regulates water balance and thirst

Controls sleep-wake cycles

Controls endocrine system

The hypothalamus isshaded blue. The pituitary

gland extends from the

hypothalamus.


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The medulla oblongata mergesseamlessly with the spinal cord and

creates the base of the brainstem.

The medulla is primarily a control

center for vital involuntary reflexes

such as swallowing, vomiting,sneezing, coughing, and regulation of

cardiovascular and respiratory activity.

The medulla is also the origin of many

cranial nerves.


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The pons is the roundedbrainstem region between the

midbrain and the medulla

oblongata. In fact, pons means

bridge in Latin.

The main function of the pons isto connect the cerebellum to the

rest of the brain and to modify the

respiratory output of the medulla.

The pons is the origin of several

cranial nerves.


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The ventricles are a complexseries of spaces and tunnels

through the center of the brain.

The ventricles secrete

cerebrospinal fluid, which

suspends the brain in the skull.

The ventricles also provide a

route for chemical messengers

that are widely distributed through

the central nervous system.


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Cerebrospinal fluid is a colorlessliquid that bathes the brain and spine.

It is formed within the ventricles of the

brain, and it circulates throughout the

central nervous system.

Cerebrospinal fluid fills the ventricles

and meninges, allowing the brain to

float within the skull.



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The brainstem is the mostprimitive part of the brain and

controls the basic functions of

life: breathing, heart rate,

swallowing, reflexes to sight or

sound, sweating, blood

pressure, sleep, and balance.

The brainstem can be divided

into three major sections.

Detailed brainstem anatomy.



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Contralateral

Homunculus

Unequal

representation


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Figure 13.10


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Aphasia impairment of language, usually caused by left

hemisphere damage either to Brocas area (impairingspeaking) or to Wernickes area (impairing

understanding) see clips Brocas Area

an area of the left frontal lobe that directs the musclemovements involved in speech

Wernickes Area an area of the left temporal lobe involved in language

comprehension and expression


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Broca Expression

Wernicke Comprehensionand reception

Aphasias

LEFT HEMISPHERE


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Paul Broca [1800s]

Suggested localization

T h i t i f ti


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Techniques to examine functionsof the brain

1. Remove part ofthe brain & see

what effect it hason behavior

2. Examine humanswho have suffered

brain damage


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3. Stimulate thebrain

4. Record brain

activity


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Corpus collosum large bundle ofneural fibers

(myelinated axons,or white matter)connecting the twohemispheres


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LEFT

Symbolic thinking

(Language)

Detail

Literal meaning

RIGHT

Spatial perception

Overall picture

Context,metaphor


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Right hemispherecontrols left side of bodyand visual field

Left hemisphere controlsright side of body and

visual field


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Epileptic patients had corpus callosum cut toreduce seizures in the brain

Lives largely unaffected, seizures reduced

Affected abilities related to naming objects inthe left visual field


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The ability of the brain toreorganize neural pathways basedon new experiences

Persistent functional changes in thebrain represent new knowledge

Age dependent component

Brain injuries


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Impoverished environment

Enriched environment


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The process by which the centralnervous system receives input fromthe environment via sensoryneurons

Bottom up processing


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The process by which the braininterprets and organizes sensoryinformation

Top-down processing


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Absolute thresholdthe minimumstimulation needed to detect a stimuluswith 50% accuracy

Subliminal stimulationbelow theabsolute threshold for conscious awareness

May affect behavior without conscious

awareness Sensory adaptation/habituation

diminished sensitivity to an unchangingstimulus


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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?


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Vestibular balance and motion Inner ear

Proprioceptive relative position of bodyparts Parietal lobe

Temperature heat

Thermoreceptors throughout the body, sensorycortex

Nociception pain Nociceptors throughout the body, sensory cortex

And the seventhand eighthand ninth


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The retina at theback of the eyeis actually part

of the brain!

Rodsbrightness

Cones color

15 lecture 8 brain structure sl .1

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