Unit 2 Flashcards
Neurophysiology
The study of the life processes of neurons
Ions
An atom or molecule that has acquired an electrical charge by gaining or losing one or more electrons
Anions
A negatively charged ion, such as a protein or a chloride ion
Cations
A positively charged ion, such as a potassium or sodium ion
Resting Potential
The difference in electrical potential across the membrane of a neuron at rest
Ion Channel
A pore in the cell membrane that permits the passage of certain ions through the membrane when the channel is open
Selective Permeability
The property of a membrane that allows some substances to pass through, but not other
Diffusion
Spread of solute molecules from an area of high concentration to an area of low concentration through a solvent until a uniform solute concentration is achieved
Electrostatic Pressure
The propensity of charged molecules or ions to move toward areas with the opposite charge
Sodium-Potassium Pumps
The energetically expensive mechanism that pushes sodium ions out of a cell, and potassium ions in
Equilibrium Potential
Movement of ions across the cell membrane is balanced
Electrostatic pressure pulling ions in one direction is offset by the diffusion force pushing them in the opposite direction
Hyperpolarization
An increase in membrane potential, becoming more negative
Depolarization
A decrease in membrane potential, becoming more positive
Local Potential
Electrical potential initiated by stimulation at a specific site
Graded response that spreads passively across the cell membrane
Weaker with time and distance
All or none property
amplitude of the action potential is independent of stimulus size
Action Potential
Rapid reversal of the membrane potential that momentarily makes the inside of a neuron positive
Created by the sudden movement of Na+ ions into the axon
After Potential
change in membrane potential that may follow an action potential
Voltage-Gated Na+ Channel
Na+-selective channel that responds to changes in the voltage of the local membrane potential.
Mediates the action potential = Has recharge period
Absolute Refractory Phase
A brief period of complete insensitivity to stimuli
Relative Refractory Phase
Reduced sensitivity, only strong stimulation produces an action potential
Post-syn Potential
Local potential initiated by stimulation at a synapse
Spreads passively across the cell membrane, decreasing in strength with time and distance
Excitatory Postsynaptic Potential (EPSP)
Depolarizing potential in a neuron normally caused by synaptic excitation
Increases the probability that the postsynaptic neuron will fire an action potential
Inhibitory Postsynaptic Potential (IPSP)
Hyperpolarizing potential in a neuron
Decreases the probability that the postsynaptic neuron will fire an action potential
Spatial Summination
The postsynaptic potentials that reach the axon hillock
Temporal Summination
The summation of postsynaptic potentials that reach the axon hillock at different times. The closer in time the potentials occur, the greater the summation.
Synaptic Delay
The brief delay between the arrival of an action potential at the axon terminal and the creation of a postsynaptic potential.
Agonist
A substance that mimics or boosts the actions of a transmitter or other signaling molecule
Antagonist
A substance that blocks or attenuates the actions of a transmitter or other signaling molecule
Degredation
The chemical breakdown of a neurotransmitter into inactive metabolites
Reuptake
The reabsorption of molecules of neurotransmitter by the neurons that released them, thereby ending the signaling activity of the transmitter molecules
Axo-dendritic Synapse
A synapse at which a presynaptic axon terminal synapses onto a dendrite of the postsynaptic neuron, either via a dendritic spine or directly onto the dendrite itself.
-Axon terminal synapses onto dendrite
Axo-somatic synapses
A synapse at which a presynaptic axon terminal synapses onto the cell body (soma) of the postsynaptic neuron.
-Axon terminal synapses onto cell body (soma)
Axo-axonic Synapses
A synapse at which a presynaptic axon terminal synapses onto the axon terminal of another neuron
-Axon terminal synapses onto axon terminal
Dendo-denritic synapses
A synapse at which a synaptic connection forms between the dendrites of two neurons
Epilepsy
major, sudden changes in the electrophysiological state of the brain that are referred to as seizures
Seizure
Abnormally synchronous electrical activity in the brain
widespread synchronization of electrical activity: broad stretches of the brain start firing in simultaneous waves
Tonic-Clonic Seizures (AKA grand mal seizure)
seizure in which neurons fire in high-frequency bursts, usually accompanied by involuntary rhythmic contractions of the body
Simple Partial Seizures (Petit mal seizure or absence attack)
A seizure that is characterized by a spike-and-wave EEG and often involves a loss of awareness and inability to recall events surrounding the seizure
Complex Partial Seizures
A type of seizure that doesn’t involve the entire brain and therefore can cause a wide variety of symptoms
Transporters
A specialized membrane component that returns transmitter molecules to the presynaptic neuron for reuse
Ionotropic receptor- Ligand-gated ion channel
A receptor protein containing an ion channel that opens when the receptor is bound by an agonist.
Excitatory Synapse
Synapse when active, causes a local depolarization that increases the likelihood the neuron will fire an action potential
Inhibitory Synapse
Synapse when active, causes a local hyperpolarization that decreases the likelihood the neuron will fire an action potential
Metabotropic Receptors
When activated, use a second-messenger system to open nearby ion channels or to produce other cellular effects
Amino Acid Transmitters
A neurotransmitter that is itself an amino acid.
-GABA
Peptide Neurotransmitters
Also called neuropeptide. A neurotransmitter consisting of a short chain of amino acids
Amine Neurotransmitters
A neurotransmitter based on modifications of a single amino acid nucleus.
-Acetylcholine, serotonin, and dopamine
Glutamate
An amino acid transmitter, the most common excitatory transmitter
GABA
Amino acid transmitter, the main inhibitory transmitter in the mammalian nervous system.
-Xanax (alprazolam) and Ativan (lorazepam)—potently activate GABAA receptors and are widely used to treat anxiety and panic attacks, as well as to aid muscle relaxation, sleep induction, ect
Co-Localization
The synthesis and release of more than one type of neurotransmitter by a given presynaptic neuron
Cholinergic
Referring to cells that use acetylcholine as their synaptic transmitter.
Found in nuclei within the basal forebrain.
project widely in the brain, to sites such as the cerebral cortex, amygdala, and hippocampus
Loss of cholinergic cells is involved with memory, inability/difficulty learning, alzheimers, ect
Dopamine (DA)
A monoamine transmitter found in the midbrain -especially the substantia nigra - and in the basal forebrain
Mesolimbocortical Dopamine
Important for the processing of reward and pleasure
Originates in the ventral tegmental area (VTA)- A portion of the midbrain that projects dopaminergic fibers to the nucleus accumbens.
Abnormalities in this are associated with schizophrenia
Serotonin
A synaptic transmitter that is produced in the raphe nuclei and is active in structures throughout the cerebral hemispheres
Participates in the control of all sorts of behaviors: mood, vision, sexual behavior, anxiety, sleep, and many other functions
Norepinephrine (NE)
Also called noradrenaline. A neurotransmitter active in both the brain and in the sympathetic nervous system.
Cell bodies in the locus coeruleus and the lateral tegmental area.
Opioid Peptides
A type of endogenous peptide that mimics the effects of morphine in binding to opioid receptors and producing marked analgesia and reward.
Synaptic transmitters
Peptide hormones, such as oxytocin and vasopressin
Route of administration (ROA)
Effects the amount of the drug that gets to the brain and how fast it gets there.
Smoking/inhalation
Intravenous injection
Ingestion
Oral
Subcutaneous/Intramuscular
Cranial
Insufflation
Oral ROA
Slow, easy onset
Only time a drug has to go through past metabolism
Loses concentration of going through metabolism
Stomach to liver to blood stream
Insufflation ROA
Through nasal cavity
Fast!
Difficulty accurate dosing
Inhalation ROA
Very Fast!
Sticks to lungs
Avoids right chamber of heart
Difficulty accurate dosing
Intravenous ROA
VERY FAST!!!
Faster a drug hits you, more addictive it is
Can collapse veins
Subcutaneous/Intramuscular ROA
Slow and sustained
Cranial ROA
Intracranial
FASTEST!
Biotransformation
Enzymes convert a drug into a metabolite that is itself active, possibly in ways that are substantially different from the actions of the original substance.
DEACTIVATION OF DRUG VIA ENZYME
Pharmacokinetics
Collective name for all the factors that affect the movement of a drug into, through, and out of the body
Binding/Simply Affinity
Propensity of molecules of a drug (or other ligand) to bind to receptors. Drugs with high affinity for their receptors are effective even at low doses
Efficacy (Intrinsic activity)
The extent to which a drug activates a response when it binds to a receptor.
Receptor antagonist drugs have low efficacy; receptor agonists have high efficacy.
Metabolic Tolerance
Repeated exposure to a drug causes the metabolic machinery of the body to become more efficient at clearing the drug
Functional Tolerance
The form of drug tolerance that arises when repeated exposure to the drug causes receptors to be up-regulated or down-regulated
Up and Down Regulate
Down-regulate- A compensatory decrease in receptor availability at the synapses of a neuron. (Agonist)
Up-regulate- A compensatory increase in receptor availability at the synapses of a neuron (Antagonist)
Cross-Tolerance
A condition in which the development of tolerance for one drug causes an individual to develop tolerance for another drug
Transmitter production
A drug may INHIBIT an enzyme that neurons need in order to synthesize a particular neurotransmitter, resulting in depletion of that transmitter.
Drugs that BLOCK axonal transport prevent raw materials from reaching the axon terminals in the first place, which could also cause the presynaptic terminals to run out of neurotransmitters
A drug (e.g., reserpine) can interfere with the cell’s ability to STORE the transmitter in synaptic vesicles for later release
Auto receptors
A receptor for a synaptic transmitter that is located in the presynaptic membrane and tells the axon terminal how much transmitter has been released
Stimulation provides a false feedback signal, prompting the presynaptic cell to release less transmitter.
Prevention of the presynaptic neuron from receiving its normal feedback tricks the cell into releasing more transmitters than usual.
Postsynaptic Intracellular Processes
Up-regulate its receptors, thus changing the sensitivity of the synapse.
Down-regulation in receptor density.
Alter second-messenger systems, with widespread effects in the brain.
First-Generation Antipsychotics/Antipsychotic or Neuroleptic
Antischizophrenic drug that shows antagonist activity at dopamine D2 receptors.
Chlorpromazine (Thorazine), haloperidol (Haldol) and loxapine (Loxitane)
Good at relieving positive symptoms of schizophrenia
Second-Generation Antipsychotics/atypical antipsychotic and atypical neuroleptic
An antipsychotic drug that has primary actions other than or in addition to the dopamine D2 receptor antagonism that characterizes the first-generation antipsychotics.
Helpful in relieving symptoms that are resistant to first-generation antipsychotics—especially the negative symptoms
Antidepressants
A drug that relieves the symptoms of depression. Major categories include monoamine oxidase inhibitors, tricyclics, and selective serotonin reuptake inhibitors (SSRIs).
Endogenous Opioids
Any of a class of opium-like peptide transmitters that have been referred to as the body’s own narcotics
Enkephalins
Endorphins
Dynorphins
Opioid Receptors
A receptor that responds to endogenous opioids and/or exogenous opiates.
-periaqueductal gray- A midbrain region involved in pain perception.
Active compounds found in cannabis
CBD
delta-9-tetrahydrocannabinol (THC)- The major active ingredient in cannabis.
-Can occasionally cause stimulation and paranoia
CBD
One of the two major types of active compounds found in cannabis. The other is THC
Hallucinogens
Also called psychedelics or entheogens. A drug that alters sensory perception and produces peculiar experiences
LSD
Also called acid. Lysergic acid diethylamide, a hallucinogenic drug
-Strongly activates serotonin 5-HT2A receptors that are found in especially heavy concentrations in the visual cortex
-Disinhibition of emotion-processing regions in the limbic system causing emotional, mystical qualities
-Can produce mood changes, introspective states, and feelings of creativity that have led to renewed interest in the possibility of using hallucinogens to treat specific psychiatric disorders, including depression, anxiety, and obsessive-compulsive disorder
-Relatively few negative side effects (although some users report long-lasting visual changes)
Amphetamine
A molecule that resembles the structure of the catecholamine transmitters and enhances their activity.
Inducing an accumulation of the synaptic transmitters norepinephrine and dopamine.
Acts within axon terminals to cause a larger-than-normal release of neurotransmitter when the synapse is activated
Interferes with the clearance of the released transmitter by blocking its reuptake and metabolic breakdown
Causes increased vigor and stamina, wakefulness, decreased appetite, and feelings of euphoria
Addiction and tolerance to amphetamine and methamphetamine develop rapidly, requiring ever-larger doses that lead to sleeplessness, severe weight loss, and general deterioration of mental and physical condition
peripheral effects, like high blood pressure, tremor, dizziness, sweating, rapid breathing, and nausea
Cocaine
A drug of abuse, derived from the coca plant, that acts by enhancing catecholamine neurotransmission.
Cocaine exerts stimulant effects by blocking the reuptake of monoamine transmitters, especially dopamine and norepinephrine. Transmitters accumulate in synapses throughout much of the brain, boosting their effects.
Crack, a smokable form of cocaine that appeared in the mid-1980s, enters the blood and the brain even more rapidly and thus is even more addictive than cocaine powder
Highly addictive
causes changes in the structure and function of many regions of the brain
Learning
The process of acquiring new and relatively enduring information, behavior patterns, or abilities, characterized by modifications of behavior as a result of practice, study, or experience
Memory
The ability to learn and neurally encode information, consolidate the information for longer-term storage, and retrieve or reactivate the consolidated information at a later time
Amnesia
Severe impairment of memory
Retrograde Amnesia- Difficulty in retrieving memories formed before the onset of amnesia
Anterograde Amnesia- Difficulty in forming new memories beginning with (AFTER) the onset of a disorder
Patient HM
The late Henry Molaison, a man who was unable to encode new declarative memories because of surgical removal of medial temporal lobe structures.
removed the amygdala, most of the hippocampus, and surrounding cortex from both temporal lobes
Declarative Memory
A memory that can be stated or described
Nondeclarative Memory
Also called procedural memory. A memory that is shown by performance rather than by conscious recollection
Patient NA
A still-living man who is unable to encode new declarative memories, because of damage to the dorsomedial thalamus and the mammillary bodies.
Korsakoff’s Disease
A memory disorder, caused by thiamine deficiency, that is generally associated with chronic alcoholism.
Damage to the frontal cortex- Probably causes the denial and confabulation
Confabulate- To fill in a gap in memory with a falsification, often seen in Korsakoff’s syndrome.
Patient KC
The late Kent Cochrane, who sustained damage to the cortex that rendered him unable to form and retrieve episodic memories
Extensive damage to the left frontoparietal and the right parieto-occipital cerebral cortex, shrinkage of both right and left hippocampus and nearby cortex
Episodic Memory/ Autobiographical memory
Memory of a particular incident or a particular time and place
Semantic Memory
Generalized declarative memory, such as knowing the meaning of a word
Skill Learning
The process of learning to perform a challenging task simply by repeating it over and over
Priming/ Repetition Priming
The phenomenon by which exposure to a stimulus facilitates subsequent responses to the same or a similar stimulus
Associative Learning
A type of learning in which an association is formed between two stimuli or between a stimulus and a response. It includes both classical and instrumental conditioning
Classical Conditioning/Pavlov Conditioning
A type of associative learning in which an originally neutral stimulus acquires the power to elicit a conditioned response when presented alone
Instrumental/Operant Conditioning
A form of associative learning in which the likelihood that an act (instrumental response) will be performed depends on the consequences (reinforcing stimuli) that follow it
Short Term Memories (STMs)
A form of memory that usually lasts only seconds, or as long as rehearsal continues. Working memory can be considered a portion of STM where information can be manipulated
Long Term Memories (LTMs)
An enduring form of memory that lasts days, weeks, months, or years. LTM has a very large capacity
Memory Processess
Encoding
Consolidation
Retrieval
Encoding
The first process in the memory system, in which the information entering sensory channels is passed into short-term memory
-Raw information from sensory channels into STM
Consolidation
The second process in the memory system, in which information in short-term memory is transferred to long-term memory
-Volatile STM into more-durable LTM
Retrieval
The third process of the memory system, in which a stored memory is used by an organism
-Stored information from LTM for use in working memory
Reconsolidation
The return of a memory trace to stable long-term storage after it has been temporarily made changeable during the process of recall.
Neuroplasticity
Also called neural plasticity. The ability of the nervous system to change in response to experience or the environment.
-Changes can be presynaptic, postsynaptic, or both
-Changes in the amount of neurotransmitter released and/or changes in the number or sensitivity of the postsynaptic receptors, resulting in larger (or smaller) postsynaptic potentials
Habitiuation
A form of nonassociative learning in which an organism becomes less responsive following repeated presentations of a stimulus.
decreased response cannot be due to failure of the sensory system to detect the stimulus or due to an inability of the motor system to respond
Hebbian Synapses
A synapse that is strengthened when it successfully drives the postsynaptic cell.
Tetanus
An intense volley of action potentials
Long Term Potentiation
Synapses made stronger by repeated stimulation (ex studying) - Neurons that fire together wire together
-Occurs in several neural circuits of the hippocampus, amygdala, and cerebellum
-Usually measured in Schaffer collaterals
NMDA Receptors
A glutamate receptor that also binds the glutamate agonist NMDA (N-methyl-d-aspartate) and that is both ligand-gated and voltage-sensitive
Drugs that selectively block NMDA receptors completely prevents new LTP in this region but not the pre-established synaptic changes
AMPA receptors
A fast-acting ionotropic glutamate receptor that also binds the glutamate agonist AMPA.
NMDA receptors cannot respond to the glutamate, because magnesium ions (Mg2+) block the NMDA receptor’s calcium ion (Ca2+) channel
Few Ca2+ ions can enter the neuron unless more glutamate is released
stronger stimulation of the AMPA receptors depolarizes the postsynaptic membrane so much that the Mg2+ plug is repulsed from the NMDA receptor’s channel, Releasing large amounts of Ca2+ into the postsynaptic neuron
NMDA receptors are fully active only when “gated” by a combination of strong depolarization (via AMPA receptors) and the ligand (glutamate).
Retrograde Transmitter
A neurotransmitter that is released by the postsynaptic neuron, diffuses back across the synapse, and alters the functioning of the presynaptic neuron.
Where are Memories Stored?
Perirhinal Cortex (MTL)- Object Recognition
-Delayed (non) match to sample
-LT object recognition
Hippocampus- Declarative Learning and memory
-Spatial learning and memory (contextual)
Cerebellum- Back of brain - Sensorimotor skills
-Blinking
-Conditioning
Striatum- Habit based learning
-Simple Stimulus - response analysis
-Egocentric Learning- Proprioceptive (internal) cues - AUTOPILOT
Amygdala- Fear and reward (Emotional) learning
Basal Conditions
1) Glutamate sticks to and activates AMPA receptors, depolarizing the cell (Make positive)
2) Mg2+ blocks the ion pore of NMDA receptors. Glutamate sticks until certain level of depolarization.
3) Block is released, glutamate is bound to NMDA receptor (SAME TIME)
Mg2+ is released THEN
1) Ca2+ floods in
2) CaMKII (Kinase) activates
3) Kinases are activated, affecting receptors
How does kinases affect receptors?
1) Makes more AMPA receptors
2) Inserts them onto the cell wall
3) Increases conductance of receptors already there
Stronger stimulation causes
1) gases are released from post-syn to pre-syn
2)Post syn relases MORE glutamate
3) More glutamate = More and stronger connections
Retrograde Messenger
Enhances transmitter release
CREB
New proteins! Turns on genes (transcription factor), making a copy of mRNA, making new muscles
CREB changes the brain by…
-Increasing neurotransmitter release (more n/t)
-Making the neuron bigger & able to receive more LG AMPA receptors (more receptors)
-Changes the way the pre-syn looks (releasing more glutamate & receptors) (both)
