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Difference in electrical charge between inside and outside cell
What are 2 factors contributing to even distribution of ions?
- Random motion
- Electrostatic pressure
Particles tend to move down their concentration gradient
Which type of motion is this?
Like repelslike, opposites attract. Is which type of pressure?
Selective permeability to certain ions & sodium-potassium pumps are factors contributing to what?
uneven ditribution of ions
The neuron at rest:
Ions move in & out through......
Ion specific channels
- K+ & CL- pass readily
- Little movement of NA+
- A- dont move at all, trapped inside
The neuron at rest:
The potential at which there is no net movement of an ion- the potential it will move to achieve when allowed to move freely is.....
- Ex; NA+ = 12-mV
- Cl-=-70mV(same as resting potential)
Na+ is driven in by both......
Electrostatic pressure (repelling) & its concentration gradient (random motion)
K+ is driven in by _____ & out by _______
- Electrostatic forces
- Its concentration gradient
Neurotransmitters bind at.....
These chemical messengers bind & cause electrical changes...
- Depolarizations ( making the membrane potential less negative)
- Hyperpolarizations ( making the membrane potential more negative)
Postsynaptic depolarizations = ?
An excitatory PSP (EPSP)
postsynaptic hyperpolarization= ?
An inhibitory PSP (IPSP)
______ Make it more likely a neuron will fire, _____ Make it less likely
_____ are graded potentials- their size varies
What is being described?
- travel passively from their site of origination
-Duration varies but transmitted at great speed
- Decremental- They get smaller as they travel
EPSPs & IPSPs
One EPSP will not suffice to cause a neuron to " fire" & release neurotransmitters, which is needed?
What is needed to generate an AP ( or fire)
The threshold of activation must be reached near the axon hillock
Integration of IPSPs & EPSPs must result in....
A potential of about -65mV in order to generate an AP
Adding or combining a # of individual signals into one overall signal is...
Integration of events happening at differnt times is....
Integration of events happening at differnt places is.....
All or none- when threshold is reached the neuron " fires" & the action potential occurs
- When the threshold is reached, voltage- activated ion channels are opened
What are the differences of APs and PSPs?
- -Passive(energy is not used)
- Conducted more slowly than PSPs
- Passive & active
- Prevent the backwards movement of APs & limit the rate of firing
- - Impossible to initiate another action potential
- -Harder to initiate another action potential
What is the conduction like in myelinated axons?
- Passive conduction( instant & decremental) along each myelin segment to next node of ranviee
- - new action potential generated at each node
- - Instant condution along myelin segments results in faster conduction than in unmyelinated axons
What are the different types of synaptic conncetions?
- Most common:
- Axodendritic- axons on dendrites
- Axosomatic- axons on cell bodies
- Dendrodendritic- capable of transmission in either direction
- Axoaxonic- May be involved in presynaptic inhibition
What are the 2 main types of NT molecules?
- Small- synthesized in the terminal button & packaged in synaptic vesicles
- Large- Assembled in the cell body, packaged in vesicles, & then transported to the axon terminal
What is the main type of Neuropeptides molecules?
- Ex: endorphines "endogenous opioids"
- Produce analgesia ( pain suppression)
- Receptors were identified before the natural ligand was
What are the small NTs types?
- Amino acids- building blocks of proteins
- Monoamines-All synthesized from a single amino acid
- Acetylcholine(Ach)- activity terminated by enzymatic degration
- Unconventional neurotransmitters-soluble gases & endacannabinoids
found at fast acting directed synapses in the CNS
Glutamate- Most prevalent excitatory neurotransmitter in the CNS
GABA- synthesized from glutamte
Most prevalent inhibitory NT in the CNS
Aspartate & glycine
are all part of which small NT
Effects tend to be diffuse
Catecholamines- synthesized from tyrosine
-Indolamines-synthesized from tryptophan
Are all part of which small NT?
Production of NTs at the terminal
- The arrival of an AP at the terminal opens voltage-activated Ca2+ channels,
- The entry of Ca2+ causes vesicles to fuse with the terminal membrane & release their contents
The process of NT release is...
A molecule that binds to another is a ?
What is associated with ligand- activated ion channels?
What is associated with signal proteins & G proteins ( molecular switches- active/inactive)?
These describe what?
-NT binds & an associated ion channel opens or closes, causing a PSP
-If NA+ channels are opened, for ex: an EPSP occurs
If K+ channels are opened, an IPSP occurs
This describes what?
Effects are slower, longer-lasting, more diffuse & more varied
They opperate in the following sequence
1-NT 1st messenger binds
2-G protein subunit breaks away
3- ion channel opened/closed OR a 2nd messenger is synthesized. 3- 2nd messengers may have a wide variety of effects
What are 2 ways of recycling NTs?
- Reuptake- scoop up & recycling NT
- Enzymatic- degration-a NT is broken down by enzymes
Increase or facilitate activity is.....
Decrease or inhibit activity is
Two examples of agonists are
- Cocaine (fight or flight)
- Benzodiazepines- (sedative, anti anxiety- GABA agonists
What are two examples of antagonists?
- Atropine- Ach , high does disrupt memory
- Curare- causes paralysis
Describe an NT cycle
- 1-NT molecules are synthesized from precursors under the influence of enzymes
- 2-NT molecules are stored in vesicles
- 3- NT molecules that leak from vesicles are destroyed by enzymes
- 4-APs cause vesicles to fuse w/the presynaptic membrane & release their NT molecules into the synapse
- 5- released NTs molecules bind w/autoreceptors & inhibit subsequent NT release
- 6- released NTs molecules bind to postsynaptic receptors
- 7-released NTs molecules are deactivated, by either reuptake or enzymatic degradation
What is this?
Inject a substance into a brain structure to increase the contrast w/surrounding
- Angiography inject dye into artery
what is this?
2-D x-ray images are combined to create a 3-d image
What is this?
Place head into powerful magnetic field, which aligns hydrogen atoms ( present in water). Then pulse the field w/brief radio waves, which knocks atoms out of aligment. Detect energy released (megnetic field) as they wobble back into place
what is this?
Relies on increased glucose consumption in active brain areas during particular kinds of info precessing
- to track glucose, participants are given a mildly radioactive form of glucose
- The brain is then scanned to detect the positrons
How does a PET work?
- Seeing- activates visual areas in the occipital lobe
- Listening- activates the temporal lobes of both hemispheres
- Speaking- activates portions of the motor cortex, the insular cortex, the middle cerebellum
- Gererating- words trigger complex activations inclduing the left frontal cortex, the anterior cingulate, posterior temporal lobe, & the right cerebellum
What are the advantages of fmri over PET?
- - nothing injected
- - provides both structual & functional info in one image
- - better spatial resolution
- - Can create 3-D images of activity over the entire brain
- Both use subtraction technique
what is this?
Is a non invasive technique that stimulates the brain using magnetic fields. It induces an electric field in the neurons of the cortex below the coil to produce brain activity
What is this?
Measures changes in megnetic field
Provides higher temporal resolution of brain activity changes than fMRI
What is this?
A measure of the average electrical activity of the brain
- ( some EEG wave forms assicated with: specific states of consciousness, cerebral pathology( such as epilepsy)
Sensory evoked potentials are triggered by sensory stimuation, is an example of...
what is used to position experimental devices w/in the brain
what is a point on the top of the skull ofter used as a reference point?
Lesion- Remove, damage, or destroy a part of the brain to observe impact on behavior
name and define the four different types...
- Aspiration-suction cortical tissue
- Radio- frequency lesions- heat destroy tissue
- Knife cuts- may damage surrounding area
- Cryogenic blockage- reversible lesion
Name and define the four different types of Electrophysiological recording....
- Intracelluar unit recording- detects graded changes in membrane potential of a neuron
- Extracellular unit recording- detects firing of a neuron
- Multiple unit recording-firing of many neurons
- Invasive EEG recording
Measuring chemical activity of the brain:
- - inject animal w/radioactive 2-DG & allow it to engage in behavior of interest
- -use autoradiography to see where radioactivity accumulates in brain slices
Measures extracellular concentration of specific chemicals in live animals
locating NTs & receptors: dye or radioactive labels used to visualize the protein of interest-uses ligands of the molecule
In situ Hybridization
- - based on the binding of labeled protein specific antibodies
- -immune response-antibodies created that bind & remove/destroy antigens( foreign proteins)
Uses artificial ( & labeled) RNA that is complementary to mRNA corresponding to protein of interest
removing a gene is called
This allows for development of gene but blocks its expression
Inserting pathological human genes in mice is...
What is the adv. of a single test?
Used to defferentiate brain damage from functional causes
What is the adv. of standardized test?
same as single test
What is the adv. of customized test battery?
- now predominant
- charaterizes nature of psychological deficits
What is the WAIS test?
- Wechsler adult intelligence scale
- an iq test
- often fails to detect memory deficits
What is the language lateralization test?
used to identify language dominant hemisphere
What is the WCST ?
- Wisconsin card sorting test
- Patient must learn the sorting rule
- Frontal lobe damage leads to repetitive guessing & failure to learn a new rule
What are some common tests with rats?
- open field test- general activity
- Colony intruder paradigm- aggression & defensive behavior
- Elevated plus maze- anxiety
What are some common conditioning tests with rats?
- Pavlovian- pairing an unconditional stimuls w/ a conditioned stimulus
- Operant- reinforcement & punishment
- self stimulation- animal works with electrical stimulus
name and define
Morris water maze
conditioned defensive burying
Tests spatial abilities-rats must find hidden platform in an opaque pool
- - following a single aversion stimulus delivered from an object, rats will spray bedding at the object
- - antianxiety drug decreases the amount of burying behavior
What are the three layers of embryonic cells?
- Ectoderm (outermost, forms CNS)
- Mesoderm (middle, forms circulatory system, bones and sex organs)
- Endoderm (innermost, forms lungs and digestive system)
what is this ?
earliest cells have the ability to become any type of body cell
What is this?
with development, neural plate cells are limited to becoming one of the range of mature nervous system cells
A structure dorsal to the neural tube and formed from neural tube cells
Develops into the cells of the peripheral nervous system
Cells migrate long distances
This is the....
radial migration and tangential migration
are 2 types of what?
Aid both migration and aggregation
CAMs recognize and adhere to molecules
What is this?
Cell adhesion molecules
Prevalent in brain development
May play a role in aggregation and other processes
What is this?
what is the first to travel a route, interact with guidance molecules
After that, other developing axons follow the established path
pioneer growth cones
what are presumed to guide connections across structures while maintaining the same layout
Topographic gradient hypthesis
Formation of new synapses
Depends on the presence of glial cells – especially astrocytes which supply the high levels of cholesterol needed
Chemical signal exchange between pre- and postsynaptic neurons is also needed
is known as
promote growth and survival, guide axons, stimulate synaptogenesis
Nerve growth factor (NGF)
is known as...
Both passive cell death (necrosis) and active cell death (apoptosis)
Apoptosis is safer than necrosis – “cleaner”
whole brain volume....
Increases until about 16 years, then decreases
71 - 80 years were smaller than 2 years
gra/white matter ration.........
- Decreases rapidly from 19 months to 50 years
- Then decreases slowly
- Due to decrease in gray matter and increase in white matter
- At 4 yrs, we have 3x more gray matter than white matter. At 50 yrs we have 1.6x more gray matter than white matter
neutogenesis in adults....
- Mature brain changes and adapts
- Neurogenesis (growth of new neurons) seen in olfactory bulbs and hippocampuses of adult mammals – adult neural stem cells created in the ependymal layer lining in ventricles and adjacent tissues
interactions betwn experience & brain development
- Tinnitus (ringing in the ears) – produces major reorganization of primary auditory cortex
- Adult musicians who play instruments fingered by left hand have an enlarged representation of the hand in the right somatosensory cortex
- Skill training leads to reorganization of motor cortex