Lecture 7: Drugs and Behavior

Question 1

Electrochemical signal

Answer 1

1. Synthesis of neurotransmitter
2. Chemical packaging of neurotransmitter
3. Release of that chemical from vehicles in the synaptic terminal of the presynaptic neuron, neurotransmitter is the synaptic cleft
4. Reception/ activation of receptors
   –> different types of receptors and different types of mechanisms as a result of that receptor activation
5. Inactivation of the neurotransmitter either through degradation or reuptake.

Question 2

Tetrodotoxin

Answer 2

• block sodium channels —> don’t have any action potential take place
• Sodium channels can’t open —> sodium can’t come on in —> can’t get to the threshold of excitation —> can’t get that big rapid depolarization that is needed for the first part of our action potential
• actually making sure that you neurons don’t talk to your muscles —> end up poisoning you —> will ultimately be fatality question

Question 3

Agonist –> synthesis of neurotransmitter

Answer 3

drugs that increase the synthesis of the neurotransmitter —> increasing the neurotransmitter amounts

Question 4

Parkinson’s

Answer 4

• a result of having decreased amounts of a neuron that works with dopamine as a neurotransmitter
• potential treatment: L-dopa (a precursor to dopamine —> dopamine can’t cross the blood brain barrier)
• give the precursor to it —> your body, your brain can start to make dopamine
• Drug L-dopa —> able to increase synthesis

Question 5

Agonist –> Drugs that facilitate release

Answer 5

• making it so that you’re releasing more neurotransmitter —> got a lot more neurotransmitter hanging out in the synaptic cleft
• Black widow spider venom –> when they release their venom, their drug (toxin their venom) —> causes the release of acetylcholine
• have a lot of acetylcholine in your synaptic cleft —> going to actually result in like excessive contraction of your muscles
• everything was contracting against it —> those muscles were receiving a whole bunch of acetylcholine at that time
• if you’re receiving all that signal, your muscles keep on contracting for extended periods of time —> cramp on steroids —> getting into like tetanus
• agonist —> increasing neurotransmitters or is mimicking the neurotransmitter

Question 6

Agonist –> Receptor activation

Answer 6

• Receptors that we find on the postsynaptic neuron –> ionotropic or metabotropic
• if you bind to them and activate them –> circumstance of mimicry —> something pretending to be a neurotransmitter and able to activate them
• Nicotine can pretend to be acetylcholine –> nicotinic receptors also get activated by nicotine — works on your muscles as well
• acetylcholine crossing over the synaptic cleft —> muscle contractions
• In some circumstances the presence of nicotine can also help out with muscle contraction

Question 7

Agonist –> Neurotransmitter inactivation

Answer 7

• if you block the breakdown of neurotransmitter —> your neurotransmitter levels increase
• Esterase usually breaks down acetylcholine —> drug that comes in and inhibits acetylcholine —> acetylcholine levels will go up —> type of treatment that’s used in myasthenia gravis
• whatever receptors on the postsynaptic neuron are available —> have a higher chance of getting activated by whatever acetylcholine wasn’t broken down because of this drug blocking the breakdown

Question 8

Antagonist

Answer 8

Drug that will decrease levels of neurotransmitter or inhibit their action in any way, shape, and form

Question 9

Agonist

Answer 9

Drugs that mimic a neurotransmitter, increase the neurotransmitter itself, or increase the neurotransmitter’s activity

Question 10

Auto receptors

Answer 10

if they get activated on our presynaptic neuron, tell presynaptic neuron —> less synthesis or less release

Question 11

Mesolimbic Dopaminergic Reward System

Answer 11

• nucleus accumbens filled with neurons that release dopamine —> talks to your frontal lobe, specifically prefrontal cortex
• Becomes activated and releases dopamine so that you can feel good —> you will do that particular behaviour again —> need this area in the first place
• reward system activation over and over again —> learned response in that way —> you want to have that feeling of dopamine flooding over your brain

Question 12

How Addiction Happens

Answer 12

• All about like flooding your brain with dopamine gets you that first initial hit —> you want to keep on having that particular flood of euphoria attributed to the dopamine —> that’s how a lot of these drugs work
• even though not contributing to your survival —> how they’re ultimately resulting in increased dopamine around your mesolimbic dopaminergic system sometimes directly, sometimes indirectly

Question 13

Increase dopamine indirectly

Answer 13

• GABA —> Main inhibitory neurotransmitter. —> go with VTA(ventral tegmental area)
• Usually VTA neurons, since it’s GABA neurons —> inhibiting dopamine neurons —> can no longer release dopamine —> levels of dopamine go down —> usual circumstance where we don’t have activation of our system
• opiates —> producing endorphins —> can get those not just from opiates, but exercise —> got natural endorphins as opposed to like morphine
• Endorphins are inhibiting the VTA neurons —> activity is going to go down —> releasing less GABA—> not so much with the inhibition of the dopamine neurons —> dopamine levels go up
• That’s how those other drugs are working with regards to indirectly increasing dopamine —> inhibition of an inhibitor results in increased dopamine
• agonists —> not a good agonist by any means
• net increase in the neurotransmitter dopamine —> result in reinforcement wanting to have increased levels of dopamine for future use

Question 14

Addiction

Answer 14

• compulsive use of the drug
• We all want to have big amounts of dopamine running through our brain
• There’s a lot of different types of stimuli that can help with that particular circumstance —> doesn’t always lead to addiction per se
• Reason —> your brain changes with the continued drug use (whatever drug of abuse it might be) —> compulsive use of the drug is trying to help us out against the brain changes that have occurred

Question 15

Brain Changes

Answer 15

• Amounts of dopamine receptors went down —> shows you have decreased numbers of dopamine receptors
• If that continued drug use —> have less dopamine receptors on your postsynaptic neuron —> need more and more of that drug in order to have the same effect
• If you have less receptors —> less EPSPs —> want that postsynaptic neuron to fire later on to release dopamine
• All the neurons themselves using it too much —> because of the huge amount of dopamine that your brain physiologically —> you’ve got too much of this neurotransmitter, you don’t need that much, so we’re going to decrease the number of receptors —> like a balance
• Homeostasis —> in order to maintain those normal physiological processes
• Detrimental for the drug addict —> just trying to survive —> without the normal release of dopamine from that postsynaptic neuron —> they’re full of pain
• Brain changes —> why drug addicts are always really feeling pain —> their amount of dopamine being released is at much decreased levels than the normal subject —> drug addiction is a brain disease
• if able to abstain —> not to do with dopamine receptors per se, but to do with like activity levels from this MRI scan —> after 100 days of abstaining from the particular drug abuse, activity levels can come back
• Metaprotropic receptors —> can induce more receptors to be created later on —> takes time

Question 16

Central Nervous System

Answer 16

Brain + spinal cord

Question 17

Peripheral Nervous System

Answer 17

• nerves being like your axon —> sending information to your muscles
• nerves are considered to be also part of your nervous system, part of the peripheral nervous system
• Can see they actually make up a larger proportion of your nervous system compared to your brain and spinal cord

Question 18

Frames of Reference:
- Superior
- Inferior
- Ventral/Anterior
- Dorsal/Posterior
- Laterial
- Medial
- Rostral
- Caudal

Answer 18

• Superior vs inferior
  
  • Superior —> going above
  • Inferior —> below would mean
• ventral vs dorsal
  
  • Dorsal/posterior —> towards the back
  • Ventral/anterior —> towards the front
• Lateral vs medial
  
  • pretend that you have this imaginary mid line that divvies up your body into symmetrical left and right
  • Towards that mid line —> medial
  • Away from the mid line —> lateral
• Rostral vs Caudal
  
  • Rostral —> towards the head
  • Caudal —> towards tail

Question 19

Planes of Reference
- Sagittal
- Longitudinal planes of section —> coronal or frontal
- Transverse plane of section/cross section

Answer 19

• Sagittal
  
  • divide up your body into left and right —> if it’ symmetrical left and right —> known as a midsagittal plane
  • Cut through my left shoulder —> parasagittal plane
    
    • para —> parallel to that mid sagittal circumstance
• Longitudinal planes of section —> coronal/frontal
  
  • Ventral and dorsal
  • When you cut your body into ventral, dorsal, or anterior/posterior —> creating frontal plane/coronal plane
  • corona —> crown || when you’re making that cut —> you’re putting on a crown
• Transverse plane of section/cross section
  
  • creating a superior end, inferior portions of your body
  • virtual slices happening through our body —> also true for when we’re looking at the brain

Question 20

somatic nervous system

Answer 20

You have voluntary movement

Question 21

autonomic nervous system

Answer 21

no voluntary or overt control —>autonomic similar to automatic —> all the things that don’t require overt control besides your heart

Question 22

sympathetic nervous system

Answer 22

• fight or flight —> faced with a mountain lion —> heart rate/breathing increases, blood flow to your brain increases
• besides fight or flight —> freeze
• Not just about exciting particular types of muscles like your heart muscle or your respiratory tract —> actively inhibiting messages to other systems that you should not be using at that time
  • Blood flow to your digestive system should be —> Involuntary —> blood flow to your stomach during a situation like this should go down —> not important to be doing any digesting at that time, not important to be feeling hungry
  • urinary system —> not important to create urine/filtering your blood —> don’t want to be wasting that energy that blood supply to your kidneys at that time
  • blood flow should decrease
  • Reproductive system —> blood flow to your reproductive system should go down
• starts at middle of spinal cord
• act on all systems of the body

Question 23

parasympathetic nervous system

Answer 23

• Trying to rest and digest, conserve energy/ to bring on board energy —> get energy by eating
• blood flow to your digestive system should go up —> get much more muscle contractions in your stomach + your intestines —> in order to facilitate
• heart rate should go down, breathing should go down, blood flow to your brain should go down
• start at ends of spinal cord
• act on all systems of the body

Question 24

Protection

Answer 24

1. Skull
2. CSF (Cerebral Spinal Fluid)
3. Meninges
4. BBB (Blood-Brain Barrier)

Question 25

Skull

Answer 25

Hard and hard bone structure –> most obvious form of protection

Question 26

CSF

Answer 26

• brain is floating in CSF —> helps to stop any of that like sudden impact or momentum that can occu –> helps to slow it down —> frontal lobe won’t hit the front of your skull
• Ventricles (two lateral ventricles, three, four) –> full of CSF
• Choroid Plexus –> Helps to create CSF in first place
• CSF in of itself —> primarily protecting you —> making that bath, also where nutrients and the light can come back and forth between the brain tissue —> pretty useful in that way

Question 27

CSF Process

Answer 27

• Cerebellum —> roof of the fourth ventricle
• After the fourth ventricle —> CSF actually leaves your brain —> goes down the middle of your spinal cord
• Cut through the spinal cord from left to right (A) —> transverse
• CSF goes down the middle of our spinal cord —> going through that cerebrospinal canal —> exits out the bottom —> starts to surround your brain
• Initially getting created in your lateral ventricles —> flows to the third ventricle —> flows to the fourth. —> down the super of spinal canal —> can see how it goes around your brain and spinal cord to help protect it
• If we have excess CSF —> it will drain through things called arachnoid granulations
• eventually it will actually become part of your blood —> excess CSF will go into special veins called sinuses —> go into your jugular vein —> back to your heart
• Should never have a big feeling with regards to —> have this continuous making of CSF —> just goes in one big loop || if we have excess —> should get drained into your blood supply + part of your nutrients
• Occasionally the flow of CSF is interrupted

Question 28

CSF Process

Answer 28

• Some type of obstruction in that flow from ventricles down through to surrounding the person’s brain —> usually happens earlier on in life, bones haven’t finished growing and fusing —> especially during childhood —> if we have a blockage in this passageway of CSF —> brain and the bone, the skull —> will grow around it —> big enlargement happening
• The brain grows around it —> sometimes it can’t withstand that type of pressure —> will have intracranial pressure occur (pressure on the brain)
• In some circumstances —> if left untreated —> will result in brain damage
• Actual shunt —> surgery, if it’s discovered sooner rather than later
  • Get the excess fluid on out —> make it become part of your normal abdominal fluid (the peritoneal fluid) —> have a lot of fluid there anyway, to protect all those visceral organs —> just becomes part of the normal fluid intake

Question 29

Meninges

Answer 29

• cushioning for your brain
• a PAD for your brain || PAD —> helps us out with regards to naming conventions of the three meningeal layer
• Closest to your bone is called Dura mater (hard mother)
• connective tissue —> super, super thick —> help to be padding + acting as seat belts for your brain —> it will attach to your skull in particular locations
• Once you come to a stop, a red light —> helping to seat belt your brain into your skull so you don’t move quite as far
• super thick
• connective tissue —> super, super thick —> help to be padding + acting as seat belts for your brain —> it will attach to your skull in particular locations

Question 30

Arachnoid Matter

Answer 30

• Depiction of the spinal cord and showing the arachnoid matter
• arachnoid matter —> spider —> webbing

Question 31

Pia Matter

Answer 31

• Layer closest to your brain is called the pia mater (soft mother)
  
  • glistens
  • All connective tissue —> very strong
  • helps to make that padding —> can withstand some aspects of protection in that way

Question 32

Blood Brain Barrier

Answer 32

• two types of blood vessels called capillaries —> smallest blood vessels in your body that help you out with gas exchange
• Left —> usually see throughout your body || right —> what we see in the brain
• No gaps in the one in the capillaries that we find in our brain —> along with the presence of one of our favourite Glia(astrocytes) —> surrounding blood vessels —> together helping to make a really good barrier to anything that’s super, super small like viruses and bacteria
• They’re missing any type of gaps in their capillaries + astrocytes of surrounding them another type of boundary —> viruses and bacteria should not be able to come from your blood into your brain tissue
• If things do pass on through —> because this is such like tight junctions between the cells —> it gets stuck there, can’t get back out
• What can pass?
  
  • Very small things like oxygen and carbon dioxide can pass
  • water has to have some help
  • glucose —> your brain is mostly all about —> needs special transporters to get on by the blood brain barrier
• Very, very good body guard against most types of things —> including things that we actually need like sugar

Question 33

occipital lobe

Answer 33

• helping us out with vision —> receives visual information
• coding is predominantly being taken place over here
• if your occipital lobe were to get damaged —> no longer be able to code visual information technically —> would not be able to see || even if your eyes are fine and dandy —> because you don’t have the brain or the appropriate part of your brain to code the information —> you can’t see

Question 34

Temporal lobe

Answer 34

• super close to your ears —> helping us out with coding auditory information
• super helpful for learning and memory —> bc the hippocampus is deep in there
• primarily known for audition (fancy word for our state of hearing or sense of hearing) + higher visual processing
• After visual information goes to your occipital lobe —> goes to the temporal lobe for a little bit more finessing
  
  • When stuff goes wrong —> temporal lobe seizures —> imagining seizures are like motor movements —> actually inappropriate electrical storm
  • If your part of the brain has action potentials happening when it shouldn’t —> in your temporal lobe —> Van Gogh had inappropriate activity in his temporal lobe —> heard stuff —> cut off his ear
  • Because of that seizures happening in his temporal lobe —> brush strokes and his paintings are very vivid —> temporal lobe also involved in higher visual processing —> believed that’s what he actually perceived —> his world of experience was actually like that —> schizophrenia
  • Auditory hallucinations believed to be stemming from this circumstance of temporal lobe seizures

Question 35

Parietal lobe

Answer 35

• Part that is just behind your central sulcus, or posterior, or dorsal to your central sulcus —> primary somatosensory cortex
• known for sensations of your body in spatial awareness
• if it’s damaged —> actually have problems with figuring out where your body is in space and time —> something as simple as putting your clothes on can be to do bc you don’t know where your joints are

Question 36

Frontal lobe

Answer 36

• just in front of that central sulcus —> primary motor cortex
• Involved in motor planning, emotional regulation

Question 37

Grey Matter vs White Matter

Answer 37

• Gray matter is the superficial structures around
  
  • predominantly soma + dendrites —> all the superficial stuff is going to be the soma of your brain
• White matter —> actually seen before —> myelin
  
  • Axons part of neuron —> white matter all about moving information because it’s in the axons
  • All those axons talking between the cerebral hemispheres, talking between the brain and the spinal cord or talking between gyri