Chapter 2. III. A Phineas Gage Level headed, calm foreman of a railroad crew (1848). An accident...

Chapter 2

III. A Phineas GageLevel headed, calm foreman of a railroad

crew (1848). An accident caused a tamping iron to go

through his head. (One of the next slides shows the path)

The injury severed the connections between his limbic system and frontal cortex. He survived

III. A – cont…This caused his personality to totally change-

he became volatileThis injury allowed us to understand the

brain before technology was available. ( I will show you a video next week about

him.)

Phineas Gage

III. B. Paul BrocaPerformed an autopsy on the brain of a

patient known as Tan (because that is all he could say) There was no physical reason for his lack of speech.

Broca found an area in the brain that showed deterioration in the frontal lobe of the left cerebral hemisphere

Now called Broca’s area- damage to this area cause expressive aphasia (meaning person can’t talk- think about stroke victims)

IV. Producing lesionsTo lesion means to damage part of the brain.

Sometimes they have to surgically remove brain tissue or sever a brain connection to help a person.

This has allowed doctors to study brain function.

VII- EEGAllows us to study the brain’s electrical

activity via electrodes placed on the scalp.

Used to study the brain during different states of arousal (sleep studies use them)

It also can be used to detect abnormalities.

The next two slides show an EEG- the 2nd one is one they are using on a young child to detect a hearing impairment.

VIII. A. CAT SCANS1. Creates a …. That shows a two dimensional view of the brain.

2. Procedure… of a contrast dye.

CAT SCANS show the structure of the brain.

Next slide shows a CAT scan of someone with Broca’s Aphasia

B. MRIIgnore the start of your notes and write thisIt uses the spin of hydrogen in water cells to read the brain (or body part)

It produces more detailed images then Xrays or CAT Scans

Useless information here… But if you have a pacemaker you can’t have a MRI (THINK BIG MAGNET!!)

MRI

2. fMRIShows more detailed information than PET

scans. (This isn’t so important to know)

Figure 5.11 Functional magnetic resonance imaging (fMRI) When the subject is in the scanner, the researchers will be able to communicate with him using an intercom system and a visual projection system. The image of the brain depicts, with colors of the rainbow, the amount of blood flow in each part of the brain, which indicates the amount of neural activity in each part.

How to tell a liar- MRI- ignore this I will talk about it next week

C. PET ScansA radioactive isotope is injected into the

person. This allows the machine to study glucose

and oxygen changes in an area of the brain.

This has allowed us to study the functioning of the brain.

A PET scan is used in many studies about what part of the brain is active when you read, talk, lie, think about specific subjects- the possibilities are endless!

Pet scan

Comparison

I. The neuron receives or sends messages.

1.

2

3.

4.

B. NeurotransmittersWe need them because there is a space

at the end of the axon (called synaptic cleft or synapse) and the message has to get to the next neuron.

1. Acetylcholine- causes contraction of skeletal muscles.Interference and/or depletion of ACh

is associated with Alzheimer’s disease.

3. GABAInhibits the firing of neurons.Valium and anticonvulsant drugs increase GABA and thus slows the firing of neurons

4. DopamineInfluences learning, movement, emotion and attention.

Lack of relates to Parkinson’sExcess relates to Schizophrenia

5. SerotoninAffects mood, hunger, sleep and arousal.

Undersupply relates to depression

6. EndorphinsThey make us happy (to Quote Legally Blonde)

They are the brain’s own pain killers

Narcotics such as heroin replace them- why withdrawal is so painful

Add in NorepinephrineThe neurotransmitter = of adrenalin

Controls alertness and arousalUndersupply related to depression

END HERE!!!!

The neuron at rest is more negative inside the cell membrane relative to outside the membrane. The resting neural membrane potential is about -70mV.

The resting potential results from selective permeability of the membrane, the presence of electrically charged particles called ions near the inside and outside surfaces of the membrane and resulting concentration and electrical gradients.

Resting potential

When sufficiently stimulated (to threshold) a net flow of sodium ions into the cell occurs (along with a movement of potassium ions out). Polarity is reversed to +40mV called the action potential.

Glial cells

(D) A high-power light-microscopic view of the cell body, illustrating the nucleus and the nucleolus. Note that the different stains highlight different aspects of the neuron.

Figure 5.6 Axon terminals This electron micrograph shows the terminals of many axons forming synapses on a portion of the cell body of a single neuron. Synaptic vesicles, filled with neurotransmitter molecules, reside within the button-like swelling of each axon terminal. In the central nervous system, the cell bodies and dendrites of motor neurons and some interneurons are blanketed with thousands of such terminals.

A synapse = A particular terminal button of an axon

The synaptic cleftThe receiving portion of another neuron, gland cell or muscle cell

Figure 3.05 A. Photomicrograph of a synapse in action taken with the electron microscope. Vesicles are releasing their transmitter chemical into the synaptic cleft. B. Schematic of the process.

(C) An electron micrographic image of the contacts between an axon from another neuron and a dendrite, illustrating the synapse formed by the opposition of the end foot of the axon and the dendritic spine of the dendrite.

FIGURE 2.2 The Parts of a Typical Neuron The drawing shows the location and function of key parts of a neuron. The photograph, made with the aid of an electron microscope, reveals actual cell bodies, dendrites, and axons in a cluster of neurons. The green coloring was added to provide contrast in the photograph to make the neurons more visible.