The brain: The source of mind and self

4Overview

The nervous system- central and peripheral

Neurons

Neuron Communication

Chemical messengers

Inside the brain

Parts of the brain

Split Brain Patients

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Organization of the nervous system

4The withdrawal reflex (automatic, does not involve the brain)

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The central nervous system

Brain

Spinal cord

A collection of neurons and

supportive tissue running from the

base of the brain down the center

of the back. Actually and extension

of the brain.

Protected by spinal column

4Structure of a neuron

Dendrites

Receive information from other

neurons and transmit toward the

cell body

Cell body

Keeps the neuron alive and

determines whether it will fire

Axon

Extending fiber that conducts

impulses away from the cell body

and transmits to other cells.

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4Structure of a neuron Your turn

Which part of a neuron is tree-like or “branchy”?

1. Dendrites

2. The axon

3. The cell body

4. The nucleus

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Your turn

Which part of a neuron is tree-like or “branchy”?

1. Dendrites

2. The axon

3. The cell body

4. The nucleus

4How neurons communicate

Axon terminals release

neurotransmitters.

Neurotransmitter enters synapse.

Neurotransmitter binds to receptors that it fits.

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Action potential A brief change in electrical voltage that occurs between the inside and outside of an axon when a neuron is stimulated.

4Neurotransmitter

Chemical released by a transmitting neuron at the synapse and capable of affecting the activity of a receiving neuron

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Major neurotransmitters

Serotonin--sleep, mood, eating

Dopamine--movement, learning, emotion

Acetylcholine (Ach), muscle action, memory

Norepinephrine- heart rate, learning, memory

(GABA)-inhibitory

4Endorphins-brain’s natural opiates, reduce pain promote pleasure

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The endocrine system

Endocrine glands release hormones into the bloodstream…

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…Hormones regulate

growth, metabolism,

sexual development

and behavior, and other

functions.

The endocrine system

Hormones

Melatonin

Regulates daily biological rhythms

Adrenal hormones

Involved in emotions and stress

Cortisol, epinephrine, and norepinephrine

Sex hormones

Regulate development and functioning of reproductive organs

Androgens, estrogens, and progesterone

4Mapping the brain

1.! Researchers study brains that have experienced disease or injury

2. Some Animal Studies Involves damaging and removing sections of animals’ brain and observing the effects.

3. EEG

4. TMS

5. PET

6. MRI

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Electroencephalogram (EEG)

A recording of neural activity detected by needle electrodes

4Transcranial magnetic stimulation (TMS)

Involves delivering a large current through a wire coil on a person’s head

Can be used to

Produce motor responses

Temporarily inactivate an area of the brain

Treat depression

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Positron emission tomography (PET Scan)

Active areas have increased blood flow.

Sensors detect radioactivity.

Different tasks show distinct activity patterns. Diagnose abnormalities or just learn about normal brain

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A method for analyzing biochemical changes in the brain as they occur, using injections of a glucose-like substance containing a radioactive element

Magnetic resonance imaging (MRI)

Magnetic fields align certain ions and compounds.

When field is removed, these molecules release energy as radio waves.

Computer calculates tissue density from radio waves.

Provides nice clear 3D images

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Method for studying body and brain tissue

A tour through the brain

Brain stem

Cerebellum

Thalamus

Hypothalamus and pituitary gland

Amygdala

Hippocampus

Cerebrum and lobes of the cerebral cortex

4The brain stem

Pons Involved in sleeping, waking, and dreaming

Medulla Responsible for certain automatic functions such as breathing and heart rate

Reticular activating system Arouses cortex and screens incoming information

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The cerebellum

Regulates movement and balance

Involved in remembering simple motor skills and acquired reflexes

Plays a small part in Analyzing sensory information

Understanding words

4The thalamus

Relays sensory messages to the cerebral cortex

Includes all sensory messages except those from olfactory bulb

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Hypothalamus and pituitary gland Involved in emotions and drives vital to survival

Fear, hunger, thirst, and reproduction

Regulates autonomic nervous system

Pituitary gland

Small endocrine gland which releases

hormones and regulates other

endocrine glands

4The amygdala

Responsible for

Arousal

Regulation of emotion

Initial emotional response to sensory

information

Plays important role in

Mediating anxiety and depression

Emotional memory

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The hippocampus

Responsible for

Storage of new information in memory

Comparing sensory information with

what the brain expects about the world

Enabling us to form spatial memories

for navigating the environment

4The cerebrum(also called”the

cortex” or the “Modern Brain”

Largest brain structure

Two cerebral hemispheres connected by the corpus callosum.

In charge of most sensory, motor, and cognitive processes

Surrounded by cerebral cortex, a collection of several thin layers of cells (gray matter)

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Lobes of the cerebral cortex

Occipital lobes (visual cortex)

Parietal lobes (somatosensory cortex)

Temporal lobes Memory, language perception, emotion, and auditory cortex

Frontal lobes Planning, creative thinking, language: also emotional regulation and complex motor movements

4Lobes of the cerebral cortex

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Your turn

Omar bumps his head and is suddenly unable to see, although

the doctor says there is nothing wrong with her eyes? Which

part of his brain did Omar damage?

1. The amygdala

2. The hippocampus

3. The occipital lobe of the cerebral cortex

4. The parietal lobe of the cerebral cortex

4Your turn

Omar bumps his head and is suddenly unable to see, although

the doctor says there is nothing wrong with his eyes? Which

part of his brain did Omar damage?

1. The amygdala

2. The hippocampus

3. The occipital lobe of the cerebral cortex

4. The parietal lobe of the cerebral cortex

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Phineas Gage-1848

Gage was a railroad construction foreman

An 1848 explosion forced a steel tamping rod through his head

Others said he was “no longer Gage”

Lost his job, worked as a sideshow exhibit

4The corpus callosum

Millions of myelinated axons connecting the brain’s hemispheres

Provides a pathway for communication

If surgically severed to treat epilepsy, hemispheres cannot communicate directly

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Split-brain experiment

4Split-brain experiment

Subjects were presented information to one or the other side of their brains.

Patients identified verbally the pictures to the right (e.g., boy’s face). Right side goes to left brain, the verbal side.

BUT, When patients were asked to POINT to the face seen, the patients pointed to the left (man’s) picture.

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Research on split-brain patients shows us that…

1.! Nearly all right-handed and the majority of left-handed individuals process language mainly in the left hemisphere.

2.! Many researchers believe in left-hemisphere dominance because cognitive skills originate here.

3.! Others insist right-hemisphere is just as important for spatial visual problem solving, art & music appreciation and is more intuitive.

4. The two hemispheres are more allies than opposites

Finally….for all you philosophy lovers….where is “The Self”?

Brain scientists explain the mind and the soul in physical terms as mainly a product of the cerebral cortex, and then frontal lobes critical. But when you say, “My mind is playing tricks on me” who is the “me” being tricked? Can we leave out that me?

Cognitive Scientist Daniel Dennett says that Mind is a series of independent brain parts dealing with different aspects of thought and perception constantly getting together to meet and “revise their drafts” of reality.

Interestingly the idea that the self is an illusion is consistent with the teachings of many spiritual eastern traditions. Buddhism teaches us that our “self” is really a collection of thoughts and feelings that shift and change from moment to moment.

But even today, with modern neuroscience and technology no one has a clear picture of how the inner life of the mind is linked to the physical processes of the brain.

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Closing Wise Words

“I used to think that the brain was the

most wonderful organ in my body. Then

I realized…… well, look what's telling me

this!”-Emo Phillips, Actor & Comedian)