Provide physical support (The glue)

Chemical Nourishment

Part of the immune system

Job is to remove dead neurons

Involved in resting potentials

Outside of the membrane is positive

Inside of the membrane is negative

(-) will flow towards (+)

(+) will flow towards (-)

More Na+ outside

More K+ inside

They flow towards the lower concentration

     From high Na+ to low Na+

Located in the membrane of all nerve cells

Moves Na+ out of the cell

Moves K+ into the cell

Against their normal inclination

This requires lots of energy

Creates the resting potential at -70mV

1. Cell is stimulated in small doeses until threshold is reached
2. At threshold, Na+ channels open, Na+ rushes out of the cell, massive depolarization
3. K+ channels open, K+ rushes into the cell, massive repolarizaiton
4. Too much K+ gathers outside the membrane, it hyperpolarizes the cell (gets more negative)
5. The sodium-potassium pump starts working and restores the resting potential

Lasts about 1ms

NO stimulus can generate another action potential

Lasts about 2-4 ms

A VERY strong stimulus is needed to generate another action potential

Action potentials are the same size the entire length of the axon

No matter how strong the impulse, the same size AP is generated

Once threshold is crossed, the action is the same

The action potential jumps from node across the myelinated areas

This greatly increases the speed of conduction

Myelin sheaths break down

Nerve impulses die out part of the way down the axon

Leads to weakness, fatigue, vision trouble, etc.

Neuron A can fire many times close together

Causes B to fire

Neuron A, C, & others fire close together

Causes B to fire

All neurons have a baseline firing rate

How frequently it fires depends on where the neuron is located

Different diseases affect this baseline firing

1. NTs are packages into the vesicles in the pre-synaptic neuron
2. Ca+ channels are activated by the action potential
3. Ca+ causes the vesicle to bind to the membrane and release the NT
4. NT binds to the post-synaptic receptors (limited by the number of receptors)

1. NTs are pumped back into the pre-synaptic cell
2. NTs attach to the pre-synaptic membrane
3. Other proteins come and destroy the NT in the synaptic cleft

Second messengers, G-proteins, neurotransmitters

All activated by an NT

Causes serious changes in the post-synaptic cell

Can take minutes to days for the changes to occur

Overall goal is to increase the amount of dopamine or serotonin left in the synapse

Mainly occurs in the NUCLEUS ACCUMBENS

Reverse the re-uptake pump

Pre-synaptic cell pumps extra dopamine into the synapse

Blocks the auto receptor

Prevents DA from attaching

Extra DA stays in the synapse

Increases release from pre-synaptic neuron

Increase the amount of vesicle fusion

Increases the amount of DA in the synapse

How many receptors on the membrane

How sensitive receptors on the membranes are to the NT in question

Receptors are less receptive to the drug

Requires more of the drug for the same effect

Things that normally activate the receptor (food, sex, etc.) no longer work

Drug has been associated with pleasurable feelings

Just seeing the drug induces craving

Cravings are severe and involve bodily changes

Peripheral Nervous System

Muscles and Skin

Part of the PNS

The heart, lungs, digestive tract, etc.

Part of the PNS

Sensorimotor information crosses over as it enters the brain

     L side of the body goes to the right hemisphere

     R side of the body goes to the left hemispher

Sensation and movement lost on the opposite of the body (R damage, L impaired)

Based on amount of damage (loss in leg, arm, or both)

Towards the back

Top of the brain

Towards the stomach

Bottom of the brain

Planning behavior, movement planning

Damaged in Parkinson's Disease and Hutchinson's Disease

Filled with Cerebrospinal Fluid

Allows for cushioning of the brain

Over production of CSF

Occurs when the skull is still soft and can be expanded

Hearing (auditory), language, emotion/motivation

Middle bottom

Sensory, touch, spatial information, memory storage

Middle top

Motor, working memory, planning, decision making,  and emotion control

In the front

Uses electrical signals

Low Risk

Moderate risk level

The more active an area, the more red on a image

Can be used to compare brain activity during different tasks or in different people
Special isotopes can be used to label specific NTs to see how these levels vary in different diseases or conditions

1. Inject a radioisotopoe that labels glucose
2. person completes a cognitive task
3. Areas in the rain activated by the task absorb the glucose and the isotopes
4. Person gets in a scanner that measures the level of isotope left in the brain

Low risk level

• Synapse firing requries a lot of oxygen
• This oxygen is pulled out of the blood, and leaves areas of the brain near the activity DEOXYGENATED
• fMRI involves passing a large magnet over body
• This records which areas of the brain are low in oxygen, therefor must have been active during the task

Measures how a single cell in an area (visual, motor) fires in response to a stimulus

Mainly sensorymotor areas

Red areas are more active in the main condition

Blue areas are less active in the main condition

An fMRI scan is only as good as the comparison

More activity could mean you do better on the task

BUT...It could also mean that it takes more resources to  do a task, that is, you do worse.

Relative Size

Depth Cue: 

Far away items are smaller

So if they are the same size on the retina, they well seem larger

Depth Cue

Distant objects are less sharp

Also have a blueish tint

Due ot particles in the atmosphere that obscure vision

Seen as more thing like

Seen in front

Owns the border of the object

4 parvocellular layers, and 2 magnocellular layers
2 of them, one on each side of the brain
Each eye gives information in the LGN but they stay separate

Major input is from the visual cortex and the rest of the brain

From layer 1-2 of LGN

To layer 4Ca

From layer 3-6 of LGN

To Layer 4Cb

Early Areas

• Rods
• Magnocellular Ganglion
• Magnocellular Layers of LGN
• Superior Colliculus
• Primary Visual Cortex

Specialized Areas

• MT
• MST
• STS

Damage to area MT of the brain

Loss of the ability to perceive motion, although perception of objects is intact

The perception of movement when none exists

Happens in VI & MT

The perception of motion in a stationary stimulus after viewing a moving stimulus

Waterfall Illusion

AREA MT

Perception of motion related to living things

Involves Superior Temporal Sulcus (STS)

Still picture that suggests motion

People remember the motion as being further along than it acutally is

Activates brain areas MT and MST

Filled with jelly like fluid

Refracts light onto the retina

Where the optic nerve leaves the eye

BLIND SPOT

Center of the Retina

Focused Vision

Where light falls when looking straight ahead

Center of the MACULA

Dense photoreceptors

All cones, and allows for the sharpest vision

Ciliary muscles contract

See close objects

Ciliary muscles relax

See far objects

The lens stiffens

Harder to go fat

Vision for near objects is impaired

Increased pressure in the fluid in the eye

Optic nerve damage and death occur

Blindness occur

Cones degenerate

Central vision lost

Peripheral vision remains due to rods

Clouding of the lens

Must surgically remove the lens & replace with a plastic one

1.  Ganglion Cells

• Amacrine cells used for communication

2.  Bipolar Cells

• Horizontal cells used for communication

3.  Photoreceptors

Peripheral Vision

Sensitive to Light

High convergence

MOTION DETECTION

Central Vision

Sensitive to color

Low Convergence

FINE DISCRIMINATION

3 types of cones

• Red
• Green
• Blue

Right Side:  Blind Spot

Center:  Scotoma

MOVEMENT

Large receptive fields

Fast AP firing

Low contrast color sensitivity

Located in the periphery

High convergence

Rods

FINE DETAIL

Small receptive field

Sustained AP firing

Color opponent cells

Located near the fovea

Low convergence

Cones