Midterm 1 Flashcards
How does heroin enter into the brain?
Heroin crosses the blood-brain barrier quickly because it is a very lipid soluble.
Very strong opiate
How does morphine enter into the brain?
Morphine crosses the blood-brain barrier a bit slower than heroin because it is a less lipid soluble.
How does Imodium Anti-Diarrheal enter into the brain?
It does not enter into the brain because it does not cross the blood-brain barrier.
What do barbiturates do?
They have a sedative and depressive effect. The sedative effect shows tolerance, but the depressive effect does not.
Name the concept:
- It occurs when a drug becomes more and more effective through repeated use.
Sensitization
How do you study the brain and get to know what each part of the brain does?
You study people who have damage in that specific area of the brain you are trying to research.
What does CT scan stand for?
Computerized Tomography
Why are CT scans a good option to photograph the brain?
They are relatively cheap and fast.
What are the cons of CT scans?
The resolution of the photographs is not great for soft tissues like the brain.
What is the mechanism of CT scans?
An X-ray beam, is projected through the head of the patient to an X-ray detector. The X-ray beam is delivered from all angles.
A computer then translates the information received from the X-ray detector into a series of pictures of the skull and brain.
What does MRI stand for?
Magnetic Resonance Imaging
What happens when a strong magnetic field is applied to the body?
The spin of very hydrogen atom proton assumes a particular direction inline with the magnetic field.
Radio frequency waves are administered to the body. This energy is absorbed by protons, changing the direction of their spin. These protons then emit their own radio waves when their spin immediately flips back to that determined by the magnet.
What is the mechanisms used by MRIs?
A strong magnetic field is applied to the body, which changes the direction of the spin of hydrogen atom protons.
By triangulating where the emitted radio waves are coming from, the scanner provides an estimate of the relative density of protons in each area of the body.
What do MRI scans primarily reveal?
The density of lipid molecules
What stands for DTI?
Diffusion Tensor imaging
What is DTI?
A variation of the MRI technique that measures the direction and speed of the diffusion of water molecules instead of hydrogen atom protons
What is DTI used to identify?
It is used to identify axon tracts in the brain.
What does fMRI stand for?
Functional magnetic resonance imaging
- Of spontaneous human brain activity.
How do fMRI scans function?
The oxygenated blood slightly distorts the magnetic field. We can infer the movement of oxygenated blood around the brain by rapidly collecting a series of images and measuring the movement of these magnetic field distortions over time.
Wha mechanism do fMRI scans use?
A rapid series of MRI scans.
It’s possible to detect changes in blood oxygenation, which reflects blood flow and correlates with neural activity. When a brain region is active, blood flow to that region quickly increases.
Why is fMRIs popular?
It’s popular because it doesn’t involve needles, surgery or radioactivity. It provides both structural and functional information with decent spatial resolution and temporal resolution.
What do PET scans stand for?
Positron Emission Tomography
What are the mechanisms of PET scans?
It involves injecting a person with radioactive compound. Radioactive sugar molecules are commonly used to detect changes in energy use in the brain.
The scanner identifies where radioactive molecules are located over time.
What molecules do PET scans use?
Radioactive sugar molecules
- Similar to glucose, but it does not break down as easily as sugar, do it stays around for hours.
What do PET scans measure?
It is used as a general measure of neural activity.
Also used to measure changes in the expression levels of neurotransmitter receptors across weeks.
What are macroelectrodes?
Metal discs that are attached to the scalp
What does an EEG measure?
It measures the electrical activity in the brain that uses macroelectrodes attached to the scalp.
It records the summed population-level activity of millions of neurons.
What can an EEG be used for?
It can be used as a diagnostic tool, since specific patters of EEG activity are associated with different states of consciousness, stages of sleep and types of cerebral atrophy.
What does EEG stand for?
Electroencephalogram
What is an experimental ablation?
It’s a lesion study. It involves the removal or destruction of a portion of the brain. Presumably, the functions that can no longer be performed following the surgery are the ones the brain region normally controls.
How can radio frequency be used to create lesions in the brain?
Small lesions can be made by passing radiofrequency current through a metal wire that is insulated everywhere but the tip.
This electric current produces heat that burns cells around the tip of the wire.
Size and shape of lesion determine by duration + intensity of burn
What is the downside of radio frequency lesions?
Axons just passing through will also be burned.
What is an excitotoxic lesion?
It’s a brain lesion produced by intracerebral injection of a glutamate rejector agonist. These drugs cause so much excitation that the affected neurons often undergo apoptosis, while axons passing through are usually spared.
What is a sham lesion?
“Placebo” procedure that duplicates all steps of producing brain lesion except for one that actually causes extensive brain damage.
What is a reversible lesion?
A temporary lesion can be achieved by injecting drugs that block or reduce neural activity in a given region.
What are some of the common drugs used to create reversible lesions?
- Voltage-gated sodium channel; blockers (stops all action potential)
- GABA receptor agonists (which hyperpolarize cell bodies
What are microelectrodes?
Thin metal wires with a fine tip that can record the electrical activity of individual neurons.
What can microelectrodes be used as?
They can be used in behaving animals to record every action potential from a given neuron. And with the newest microelectrodes, it is possible to record from hundreds of single neurons simultaneously.
During which surgery are microelectrodes implanted in the brains of animals?
Stereotactic surgery
What is the difference between chronic electrical recordings and acute recordings?
chronic electrical recordings are made over an extended period of time.
Acute electrical recordings are made over a relatively short period of time.
What do we use electrical stimulation for?
To know how the activity of specific receptors or cell populations influences behaviour.
How does electrical stimulation work?
It involves passing an electrical current through a wire inserted into the brain.
This will affect everything in the area.
Some electrical stimulation patterns counterintuitively, tend to produce the same behavioural effects as lesioning the brain area.
How do chemical stimulations work?
Is achieved with drugs. They are administered through a guide cannula implanted into a particular brain region.
What are ontogenetic?
It refers to the use of light to control neurons which have been made sensitive to light though the introduction of foreign DNA. This foreign DNA encodes light-sensitive proteins known as opsins. Opsins are proteins that are sensitive to light.
What are opsins?
Opsins are proteins that are sensitive to light.
What are the steps to ontogenetics?
1) a light-sensitive protein from algae
2) Take the gene for this protein
3) Insert the DNA into specific neurons in the brain
4) Neurons communicate by firing. This is an electrical signal created by opening and closing ion channels
What can opsins be used for?
It can be used to either pulse light or leave it on to drive action potential activity. It can also be used to inhibit action potential activity in animals.
What are the steps to Viral-Meditated Gene delivery?
1) You take a light-sensitive protein from algae. It’s a protein that is an ion channel and opens in response to blue light.
2) You take the gene for this protein and insert it into the DNA of a hollowed-out virus.
3) You insert the virus into the brain
What is a virus?
It’s a type of DNA delivery system. Viruses normally replicate by injecting viral DNA into a host organism. Virus DNA contains instructions on how to make more virus.
It’s a small infectious agent that replicates inside the cells of other organisms.
We can target opsin expression to specific neurons in the brain according to?
1) where their soma are located
2) Where their axons are located
3) The proteins they express
4) Whether they recently had more action potentials than normal
Why is monitoring GCaMP protein fluorescence a good way to measure neural activity?
Researchers modified it to bind to calcium and fluoresce much brighter when it does. Since a little calcium influx always occurs during action potentials, the cells will fluoresce bright and we can measure neural activity this way.
What is retrograde labeling?
Tracing afferent axons
- It is used to label the cells that innervate (project to) a given region.
What is anterograde labeling?
Tracing efferent axons
- It is used to label where the axons from a particular region go to.
What is stereotactic surgery?
It’s a surgical intervention that uses a stereotactic apparatus. That is a device that permits a surgeon to put something into a very specific part of the brainé
It is used to inject things into the brain, such as drugs, viruses, or tracer molecules.
It can be used to permanently implant things, like cannula, electrodes or fibre optic cable.
What is the Bregma?
It’s the junction where pieces of skull fuse together. It is often used as a reference point for a stereotactic brain surgery.
What are the common reasons stereotactic surgery is used for?
- Lesion a brain area
- Lesion a specific type of cell in a particular brain area
- To change gene expression
- To implant a guide cannula to allow for later infusions of drugs
- To implant microelectrodes for stimulation or recording experiments
- To implant fibre optic cables to allow for imaging or stimulation using ontogenetic techniques
What can microdialysis be used for?
It can be used in behaving animals to measure changes in neurotransmitter levels in a given brain region.
Name the technique:
- Refers to the use of a semipermeable membrane to either deliver molecules to or measure the amount of molecules in some solution or brain area.
Dialysis
What is a microdyalisis probe?
Small metal tube that holds dialysis tubing. These can be places in the animal’s head.
Name the method:
- A histological method that is used to label proteins and peptides in biological tissue.
Immunohistochemistry
What is immunihistochemistry used for?
It is the most common technique for identifying cells that make a specific protein. This technique takes advantage of antibodies, which are proteins made by the immune system of mammals.
How do researchers use immunohistochemistry?
They have made fluorescent antibodies that selectively bind to all different types of protein. When these fluorescent antibodies are washed over a brain slice, the protein of interest will becom fluorescent lay labeled, and under a microscope, it is easy to identify which cells contain these proteins.
How do researchers identify cells that make and release classical neurotransmitters?
They use antibodies agains the enzymes that make those neurotransmitters . Therefore, the antibodies that label a certain enzyme can say what neurotransmitter is associated with which neurotransmitter.
What is acetylcholine?
Neurotransmitter
What is the primary role of acetylcholine?
It primarily acts as a neuromodulator, often at axoaxonic synapses.
~ In the central nervous system ~
What is Acetylcholine’s role in the peripheral nervous system?
It activates the fast excitatory ionotropic receptors on muscle cells that cause muscle contraction.
How does synaptic vesicle recycling work?
Vesicles release neurotransmitters on the membrane and then move to the recycling site where they recuperate the neurotransmitters and bring them back to the recycling pool to be reused in the next action potential.
Which neurotransmitter release is triggered by the black widow spider venom?
Acetylcholine
What is the botulinum toxin (Botox)?
It is produced by bacteria that grow in improperly canned food.
- It’s an acetylcholine system antagonist, because it prevents the release of acetylcholine causing muscle paralysis.
name the drug:
- Drug that inhibits activity of actylcholinesterase, which is the enzyme that breaks down acetylcholine in the synaptic cleft. It causes acetylcholine to hang around the synapses for longer periods of time.
Neostigmine
In which hereditary autoimmune disorder does one’s own immune system attack their healthy acetylcholine receptors?
Myasthenia Gravis.
What do antipsychotics do in the brain?
They bind to more than one type of receptor, but the one action they all have in common is they directly block the dopamine D2 receptor, which is an inhibitory metabotropic receptor expressed by neurons all over the brain.
Name 4 drugs that directly activate serotonin 2A receptors.
- Mescaline
- Psilocybin
- LSD
- Lisuride
How do hallucinogens cause hallucinations?
- When they bind, they launch an intracellular signaling cascade that starts with the G protein. They also activate an additional G protein known as G i/o. It’s this second G protein that causes hallucinations.
What is biased agonism?
When a metabotropic ligand causes the receptor to preferentially activate one type of intracellular G protein, whereas another ligand at the same receptor might preferentially activate a different G protein.
What is the difference between direct agonists/antagonists and indirect agonists/antagonists?
Direct affect postsynaptic receptor activity by directly binding to postsynaptic receptors.
WHILE
Indirect affect postsynaptic receptor activity in an indirect manner, the proteins they bind to are not postsynaptic receptors.
By which criteria’s are drugs categorized?
- According to their behavioural effects
- According to their physiological effects
- According to their actions on specific proteins
- According to their effects on postsynaptic receptor activity
What are competitive agonists and antagonists?
Competitive agonists
- Activate the receptor by binding where the neurotransmitter normally binds
- Full agonists
Competitive antagonists
- Attaches to the same binding where the neurotransmitter normally binds, but it doesn’t activate the receptor.
- Full antagonists
What are non-competitive agonists and antagonists ?
Non-competitive agonists
- Fully or partially activates the receptor
Non-competitive antagonists
- Fully blocks receptor activation. It doesn’t compete for the neurotransmitter binding site. It always wins without competing by binding to an alternative site.
What are allosteric modulators?
non-competitive drugs that only influence receptor activity when the neurotransmitter is also bound to the receptor.
Where are conventional neurotransmitters made ?
In axon terminals.
What are conventional neurotransmitters made from?
Precursor molecules (generally from amino acids).
What controls the synthesis of neurotransmitter from precursor molecules?
It is controlled by enzymes.
What controls the clearance of neurotransmitters from the synapse?
Reuptake transporter proteins
Enzymatic deactivation
Which drugs block the reuptake of cat Echols mine neurotransmitters, block the dopamine and norepinephrine reuptake transporters?
Methylphenidate and cocaine, etc.
Which drugs reverse catecholamine transporters, causing dopamine and norepinephrine molecules to flow directly out of the presynaptic terminal?
Adderall + Crystal meth
What is a dose response curve?
It’s a graph of the magnitude of an effect of a drug as a function of the amount that is administered. It is obtained by giving subjects various doses of drug.
Name the process:
- Process by which drugs are absorbed, distributed within the body, broken down and excreted.
Pharmacokinetics
What are the 3 key considerations when choosing a route of administrations?
1) Does the drug naturally cross the blood-brain barrier?
2) Is it better to have a high concentration of a drug for a short time or a low concentration of drug for a long time?
3) Where in the body are the enzymes that break down the drug? (Stomach, blood, liver, brain…)
What are the first cells during development called?
Neural progenitor cells
After how many days does symmetrical cell division end and asymmetrical cell division during development start?
40 days after conception
What is the midbrain?
A collection of nuclei that orchestrate complex reflective behaviours
Consists of two parts
- Tectum
- Tegmentum
What are the superior colliculi of the tectum involved in?
They are involved in orienting the animal to things seen in peripheral vision.
What do the inferior colliculi of the tectum involved in?
They are involved in orienting to unexpected sounds.
What does the Tegmentum do?
It includes several structures that coordinate and motivate complex species-typical movements. Some areas process pain and orchestrate behavioural responses to threats.
What is the role of the hypothalamus?
Regulates autonomic nervous system activity.
- Involved in behaviours that directly relate to survival
- Control body temperature, sleep-wake cycles, hunger, social behaviour, etc.
- Link to nervous system and endocrine system via the pituitary gland.
What does the thalamus do?
It relays ascending sensory information to different regions of the cerebral cortex.
What is the difference between gray matter and white matter.
Gray matter —> high concentration of cell bodies
white matter —> large concentration of myelinated axons. Very few neurons in this area.
What are the 4 lobes of the cerebral cortex and their roles?
Frontal lobe —> controls movement
Parietal lobe —> processes touch information
Occipital lobe —> processes visual information
Temporal lobe —> processed auditory information
Where is taste processed?
Insular cortex
Where is smell processed?
Piriform cortex
Name the primary cortical areas.
- Primary motor cortex
- Somatosensory cortex
- Primary visual cortex
- Primary auditory cortex
- Insular cortex
Where is the primary motor cortex located?
Frontal lobe
Where is the somatosensory cortex located?
Parietal lobe
Where is the primary visual cortex located?
Occipital lobe
Where is the primary auditory cortex located?
Temporal lobe
Where is the insular cortex located?
Hidden in the lateral fissure
What does the sensory association cortex do?
Perception takes place there and memories are stored there.
Receives information from each primary sensory area of the cortex.
What is the role of the basal ganglia?
Regulate intentional movements, motivation, reinforcement learning and habits.
What is the role of the hippocampus?
Critical for explicit memory formation
What is the role of the amygdala?
Critical for feeling and recognizing emotions, particularly fear.
What are the classical neurotransmitters?
Glutamate
GABA
Dopamine
Norepinephrine
Acetylcholine
Serotonin
What are the 4 main neuromodulators?
Dopamine
Norepinephrine
Acetylcholine
Serotonin
What is the main excitatory neurotransmitter?
Glutamate
What is the main inhibitory neurotransmitter?
GABA
Why are the neuromodulators distinguished from the other classical neurotransmitters?
- They don’t produce simple excitatory or inhibitory effects in the central nervous system
- Most of their receptors are G protein coupled receptors
- They often diffuse short distances outside of the synapse —> influence activity of neighbour neurons
What are the monoamine neuromodulators?
Serotonin, dopamine, norepinephrine
What are monoamine neuromodulators?
They are all packed by the protein vesicular monoamine transporter.
How does the G protein work?
It uses GTP molecules, instead of ATP molecules. G proteins ar activated temporarily because they have a tendency to convert GTP to GDP.
How do G protein-gated ion channels work?
1) Neurotransmitter binds to a metabotropic receptor
2) Activated G proteins transmit the message inside the cell.
3) Some ion channels are gated by activated G proteins.
Where can synapses form?
1) Dendrites
2) Dendritic spines
3) Soma
4) Other axon terminals
What is an autoreceptor?
A receptor located on presynaptic membrane that gets activated when the cell releases its own neurotransmitter.
- gated by neurotransmitter that the cell releases.
- Generally metabotropic and inhibitory.
What are the anatomical directions?
Dorsal
Anterior. O. Posterior
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Ventral
What is the definition for contralateral?
Structures on opposite side of the body
What are the ipsilateral?
Structures on the same side of the body.
What is myelin created by in the central nervous system?
oligodendrocytes
What is myelin created by in the peripheral nervous system?
Schwann cells
What is the blood-brain barrier?
Semipermeable barrier between the blood and the brain.
What are the 3 types of meninges?
- Dura mater
- Arachnoid membrane
- Pia mater
What is the dura mater?
Outer layer of meninges. Thick, tough, unstretchable tissue.
What is the arachnoid membrane?
Middle layer of the meninges. Soft, spongy, web-like appearance.
What is the pia mater?
Third layer. Closest to the brain.
Space above it has blood vessels.
What subarachnoid space?
Between the arachnoid membrane and pia mater and is filled with cerebrospinal fluid (CSF).
What is the cerebrospinal fluid made of?
Choroid plexus
What is the principal function of the spinal cord?
Distribute motor fibres to the effector organs of the body and to collect somatosensory information to be passed on to the brain.
Certain degree of autonomy on reflexes.
What are the two major divisions of the nervous system?
- Somatic
- Autonomic
What is the somatic nervous system?
It interacts with the external environment.
- Afferent nerves —> carry sensory signals from 5 senses to central nervous system
- Efferent nerves —> carry motor signals FROM the CNS to skeletal muscles
What is the autonomic nervous system?
Regulates body’s internal environment.
- Afferent nerves —> carry sensory signals from internal organs TO CNS
- Efferent nerves —> Carry motor signals FROM CNS to internal organs.
Sympathetic autonomic nervous system vs Parasympathetic autonomic nervous system.
Sympathetic
- Primes the body for action, life threatening situations
- Fight or flight response
- Higher blood flow, respiration, etc.
- Stops unimportant to survival systems like reproductive and hunger.
Parasympathetic
- Supports activities when body is in a relaxed state.
- involved in increasing the body’s energy stores (digestion).
- Sexual arousal, defecation, urination, salvation.
- Rest and digest state.
What are the functions of the medulla oblongata?
Heart rate
Blood flow
Breathing
Vomiting
Sneezing, etc.
Reticular formation
- Sleep and arousal
What are the functions of the pons?
Hearing
Balance
Taste
Sensations and movements of the face
What are the functions of the cerebellum?
Motor control.
- Does not initiate movement, but contributes to its coordination, precision, accurate timing.
- Smoothing effect on movement.
- Motor learning
In genetics, what is a promoter?
A region of DNA that initiates transcription of a particular gene. They indicate what kind of cells should read the gene and when.
What are glial cells and what are their roles?
Found all around neurons.
- Help traffic nutrients and maintain molecular stability in the extracellular space.
3 types of glial cells
- Astrocyte
- Microglia
- Oligodendrocytes
What are the 3 types of glial cells?
-Astrocyte
- Microglia
- Oligodendrocytes
What does an Astrocyte glial cell do?
Provides physical support and cleans up debris in the brain through phagocytosis
What is the function of Microglia?
They provide an immune system for the brain and protect the brain from invading microorganisms.
What is the function of oligodendrocytes?
They produce myelin sheaths.
What is the impact of myelination on action potential?
Action potential appears to jump from one node of Ranvier to the next, where there are ion channels. Action potential is much faster and more certain.
What are ionotropic receptors?
Ion channels
What are metabotropic receptors?
G protein coupled receptors that can open ion channels through intracellular signaling cascade
Which two mechanisms keep neurotransmitter signaling in the synapse brief?
- Enzymatic deactivation
- Reuptake
