PSYC 2200 Week 1 expanded

Skin conductance response

Heightened emotional response characterized by increase electrodermal activity in the palms (gut feeling response)

Neural circuits

Neuron collaboration that produces behavioral or physiological responses

Synapse

Gap between the axon of one neuron and dendrite of the next

Hodgkins and Huxley's idea

The brain and electricity are related

3 things Hodgkins and Huxley needed to test their idea

1. 2 electrodes (to compare electrical difference between two places)

2. Amplify signal (build amplifier)

3. Oscilloscope (measures oscillations: + or - change) (built this too)

Conduction velocity

the speed at which an action potential travels down an axon

Difference between axons in invertebrates and vertebrates

Vertebrates have myelin but invertebrates don't so they make up for it by having really thick axons to speed up signaling

Resting membrane potential

-70 mV

How batteries work

It starts with a big electrical difference; all of the positive and negative ions are on opposite ends of the battery. The difference decreases until equilibrium is reached, at which point the battery has died

What type of membrane do neurons have?

Selectively permeable

-some things never come out of the axon because they are too big or negatively charged (ex: proteins)

Concentration gradient of Na+ and K+ at rest

[Na+] outside > inside

[K+] inside > outside

Sodium potassium pump

Pumps 3 Na+ out and 2 K+ into the cell repeatedly. This is what causes the negative resting potential (less positivity outside, more positivity inside)

-always working to keep the uneven distribution (gradient)

Axoplasm

cytoplasm of axon

K+, Na+, Cl-: which can always move freely across the membrane?

Cl- only

Nernst equation predicts

Voltage across a membrane based on the concentration of a certain ion on the outside and inside of that membrane

-constant is + or - based on the charge on the ion

Na+ is +57 mV

K+ is -78 mV

Voltage across membrane using Cl-

-69 mV; this is very close to the resting potential because Cl- is freely moving across the membrane

Voltage gated ion channel

When a certain voltage is reached, gate opens and ions (whichever ion the specific channel is for) can flow freely through

Voltage gated Na+ channel/sodium influx

When a certain voltage is reached, proteins in the cell membrane move in such a way that creates a hole that Na+ can flow through so it floods into the cell because of the direction of the electrical and chemical gradients

-it reaches the point predicted by the Nernst equation if it were a freely moving ion (-70 mV) (because for a moment it was freely moving)

Voltage gated K+ channel/K+ efflux

Same idea as Na+ channel (see voltage gated Na+ channel flashcard) but K+ flows OUT of the cell

Depolarization

When sodium is flowing in, so the inside of the cell is becoming more positive

-the upslope on the graph

Repolarization

When potassium is flowing out, so the inside of the cell is becoming less positive

-the downslope on the graph

Hyperpolarization

When the membrane potential becomes more negative

-the little dip after the action potential on the graph before it returns to -70 mV

-overshoots going back to the resting potential because K+ channels are slow to close

-Na+/K+ pump cleans up the mess to bring the voltage back to resting potential

Refractory period

The time period after an action potential sequence that sets a maximum limit on a neuron's firing frequency

-time spent putting things back to where they're supposed to be before another action potential can happen

-same area on the graph as hyperpolarization (dip below resting potential)

Absolute refractory period

the first part of the refractory period where no amount of stimulation can trigger an action potential

Relative refractory period

The second part of the refractory period where a greater change in membrane potential than usual is required to trigger an action potential

All or none law

all action potentials have the same strength, speed, size, shape, and duration regardless of the triggering stimulus

-a neuron can have more action potentials or there can be more neurons firing but none can be bigger

Saltatory conduction

Jumping movement from 1 node of ranvier to another (enhances speed of neural communication)

Spike-initiation zone

Area where the action potential is initiated

Progesterone

Reproductive hormone that can remyelinate axons affected by demyelinating diseases like MS

CT scan

Use x rays and computer technology to provide horizontal images of the brain

PET scan

Convey real time images of functioning areas of the brain involved in various tasks
-uses radioactive labeled glucose inserted into the bloodstream

MRI

High resolution images showing brain structure

DTI (diffusion tensor imagining)

Shows brain constitution, uses movement of water in the brain to detect characteristics of the fibers that make up the white matter (communication pathways)

fMRI

measures brain activity by detecting changes associated with blood flow and oxygenation

Aristotle

He did not think the brain controlled behavior because of how you could cut off a chicken's head and it would still run

Ganglia

Cell bodies outside of the CNS

-in every body segment

-perform basic nervous functions for reflexes

Gaylin

Physician for gladiators

-realized that those with head injuries acted different after the injuries

Frisch and Hitzig 3 findings

1. The brain is electrically excitable

2. Regional specificity

3. Replicable (same result every time)
   -they used dogs and a portable battery

Lateral view

side view

Dorsal view

Top view

Does the brain have pain receptors in it?

No

Robert Bartholow 4 contributions

1. Real evidence for electrical control of brain and that brain controls behavior

2. Applies to people

3. Similarity/continuity across species

4. We should study animals

transcranial magnetic stimulation and direct current stimulation were novel because

They could be done through the skull

John Flynn 2 results from experiments

1. Affective defense behavior: when one part of the hypothalamus was stimulated, cats went into aggressive mode

2. Quiet biting attack: when different part of hypothalamus was stimulated, cats went into sneaking up on prey mode

John Flynn 2 contributions

1. Brain stimulation can elicit behaviors more complex than just a muscle twitch

2. A different location of stimulation even within the same brain area leads to a different behavior

Sagittal section

Mid view (cut through the middle vertically)

Wilder Penfield 4 contributions

1. Different area of stimulation creates different response
2. Replicable between different people
3. Brain processes sensory and motor stimulation. Can tap into memories
4. Stimulation also leads to memory and emotion. If we can put it in out brain, we can also get it back out

Aura

The feeling that you are about to have a seizure

-different for different people

-seizures typically start in the same brain area that is responsible for the aura

How is brain activity during seizures different than it is normally?

Typically, brain activity is asynchronous, but with seizures, it becomes synchronous and everything fires simultaneously

Michael Gazzaniga work

-worked with people whose seizures started in brain areas that cannot be removed

-worked with severing the corpus callosum

Intractable epilepsy

Not responsive to drugs for seizures

Ipsalateral

Same side

Contralateral

Opposite side

-the right side of the body is controlled by the left side of the brain and vice versa

90% of language is in the ___ side of the brain for right handed people

Left

Facial recognition tends to be on the ____ side of the brain

Right

Findings after severing the corpus callosum

-hemispheres can't communicate or form one whole picture

-for example, if the right hand picks up an object, you can name it. But if the left hand picks it up, you usually can't

Biofeedback techniques

Used to alter autonomic functions

Insular cortex/insula

Located in the cerebral cortex (outer layer), provides representations of the "state of the body" to other relevant brain areas by integrating input from the body and the environment

Interoception

The ability to monitor the body's internal processes

-facilitated by the insular cortex

Neuron

a nerve cell; the basic building block of the nervous system

Histological technique

Method to study the microscopic structure of tissues (view neurons)

Neuron doctrine

The idea that neurons are discrete units

Soma

Cell body

Dendrites

Branchlike parts of a neuron that receive information

Axon

A threadlike extension of a neuron that sends nerve impulses away from the cell body

Multipolar vs bipolar vs monopolar neurons

Multiple dendrites (most common) vs 2 vs 1

Dendritic spines

short outgrowths that increase the surface area available for synapses

Axon hillock

Cone shaped region (also referred to as a bump) of an axon where it connects to the cell body

Myelin sheath

A layer of fatty tissue that covers the axon in segments that speeds up the transmission of neural impulses

-composed of oligodendrocytes in the brain, wrap around axon and speed it up

What types of cells are myelin made up of? In which locations?

2 types of cells can be myelin: oligodendrocyte in CNS and Schwann cells in PNS

Nodes of ranvier

gaps in the myelin sheath

Terminal ending

the end of an axon where a nerve impulse or message is transmitted to another neuron or to non neuronal tissue, such as a muscle or gland

Axon collateral

branch of an axon

Nissl stain

Stains the ER, therefore the cell body so you can tell regional differences

-with medium power you start to see individual cell bodies and this hints that there are different functions for different locations

High magnification nissl stain shows

That there are different types of cells in the brain. Big ones are neurons and smaller ones are glia

Glia were originally thought to

Support neurons

4 types of glial cells

Astrocytes, oligodendrocytes/Schwann cells, microglia, radial glia

Astrocytes

Maintain the environment around the neurons (support neurons), line all spaces between the brain and the outside world (line all blood vessel and brain surface) (barrier)

Oligodendrytes

Support cells that cover the axon (form myelin) in the CNS

Schwann cells

Support cells that cover the axon (form myelin) in PNS

Microglia

Scavenger cells in the brain, clean up debris, especially after brain damage

Radial glia

Only found in early life

-they line a fluid filled space in which baby neurons are born. The baby neurons climb on radial glia to get out and go to the location where they should be as a mature neuron

Golgi stain

Stains a full neuron

-only 1-5% of neurons take up the stain so you can clearly see how they connect together

Golgi and Cajal beliefs

Golgi said that neurons touch each other (nerve net theory), and Cajal (years later) said that they don't (neuron doctrine)

If dendrites are
-big, thick
-bumpy, spines
-acute angles (branch)
-input

axons are…

Axons
-fine, small
-smooth
-right angles (collateral)
-output

Anterograde tracing

Forward

-whatever cell bodies it is injected into take the dye and move it down using the cytoskeleton and move it to the end of synapses, so you can trace where a neuron is projecting to

Retrograde tracing

Backward

-if injected into a brain area with axon terminals, this dye gets picked up by those and transported back up to the cell body

Why is it called axon “collateral”?

collateral can refer to a descendant of something; it descends from the axon “trunk”

salatory conduction

the jumping movement of an action potential from one short unmyelinated section of axon (that also possesses myelinated sections) to another. It greatly enhances the speed of neural processing