Ascending Tracts | Pain Modulation: Gate Control Theory

Summary

This educational video script delves into the complex mechanisms of pain modulation, emphasizing the importance of the gate control theory and the descending analgesic system. It explains how endogenous chemicals like GABA, endorphins, and dynorphins work to inhibit pain at the spinal cord level. The script also highlights the role of higher brain structures in modulating pain perception, providing insights into our body's innate pain management system.

Takeaways

• 🧠 Pain modulation is crucial and involves endogenous systems within the body that help inhibit pain.
• 🔄 There are two primary types of pain modulation: the Gate Control Theory and the Descending Analgesic System.
• 🚪 Gate Control Theory suggests that non-painful touch receptors can 'close the gate' on pain signals, reducing the perception of pain.
• 🌟 The Gate Control Theory involves the activation of inhibitory neurons that release chemicals like GABA to decrease pain signals in the spinal cord.
• 🛑 The Descending Analgesic System involves higher brain structures that send signals down to the spinal cord to modulate pain.
• 💊 Descending pathways can release endogenous opioids, such as enkephalins and dynorphins, which are similar to morphine and help reduce pain.
• 🌐 The periaqueductal gray matter (PAG) and periventricular gray matter are key regions in the brain that regulate the Descending Analgesic System.
• 🔻 The locus coeruleus, rich in norepinephrine, and the raphe nuclei, rich in serotonin, are involved in the Descending Analgesic System and influence pain modulation.
• ⚡️ The release of neurotransmitters like substance P and glutamate at synapses in the spinal cord determines the speed and intensity of pain signals.
• 🔄 The spinothalamic tract is a key pathway for pain and temperature signals, with C fibers primarily responsible for slow pain and A-delta fibers for fast pain.
• 📡 Higher brain structures, such as the limbic system, sensory cortex, and insular cortex, can influence the PAG and pain modulation through descending pathways.

Q & A

What is the main topic discussed in the video?

The main topic discussed in the video is the modulation of pain, specifically the endogenous analgesic systems that regulate pain within our bodies.

What are the two types of pain modulation mentioned in the video?

The two types of pain modulation mentioned are the gate control theory and the descending analgesic system.

What is the gate control theory and how does it work?

The gate control theory is a mechanism that modulates pain at the spinal cord level. It works by activating touch receptors when we rub an injured area, which in turn stimulate inhibitory neurons that release chemicals like GABA to inhibit pain signals.

What are the roles of A-delta and C fibers in pain transmission?

A-delta fibers are responsible for transmitting fast pain signals, releasing the neurotransmitter glutamate at the synapse. C fibers transmit slow pain signals and are believed to release substance P at the synapse, which is slower and can also decrease the threshold for pain.

What is the role of the substantia gelatinosa of Rolando in pain modulation?

The substantia gelatinosa of Rolando is a structure in the Rex lamina of the spinal cord that plays a crucial role in pain modulation. It is where C fibers synapse and is involved in the gate control theory by being influenced by inhibitory neurons stimulated by touch receptors.

What are the main structures involved in the descending analgesic system?

The main structures involved in the descending analgesic system include the periaqueductal gray matter, periventricular gray matter, locus coeruleus, reticular formation, and the raphe nucleus magnus.

Which neurotransmitters are associated with the descending analgesic system and their respective structures?

The locus coeruleus is associated with norepinephrine, while the reticular formation (para giganto cellular reticular nuclei) and the raphe nucleus magnus are associated with serotonin (5-hydroxytryptamine).

How do the descending analgesic pathways reduce pain perception?

The descending analgesic pathways reduce pain perception by releasing chemicals such as norepinephrine and serotonin onto inhibitory neurons, which in turn release endogenous opioids like enkephalins and dynorphins that inhibit the substantia gelatinosa from sending pain signals up the spinal cord.

How do higher brain structures influence the descending analgesic system?

Higher brain structures such as the limbic nuclei, sensory cortex, insular cortex, hypothalamus, and cingulate gyrus can influence the descending analgesic system by sending signals to the periaqueductal and periventricular gray matter, indicating when to activate the descending pathways.

What are the endogenous opioids released by the descending analgesic system and their function?

The endogenous opioids released by the descending analgesic system include enkephalins and dynorphins. These natural opioids function similarly to morphine, inhibiting pain signals at the spinal cord level.

Outlines

00:00

🧠 Pain Modulation and Endogenous Systems

This paragraph introduces the concept of pain modulation, emphasizing its importance alongside the pain pathway itself. It mentions the anterior lateral system and the spinothalamic tract, hinting at a recap without deep dive. The focus is on two types of endogenous pain modulation systems that the body uses to inhibit pain: the gate control theory and the descending analgesic system. The gate control theory is introduced with a scenario of bumping one's head to illustrate how rubbing the area can alleviate pain by activating different touch receptors.

05:00

🔬 Neurotransmitters in Pain Pathways

The second paragraph delves into the role of neurotransmitters in pain pathways, specifically substance P for slow pain and glutamate for fast pain. It explains how C fibers and A-delta fibers activate different second-order neurons and the synapse points involved. The paragraph also touches on the chemical factors released due to stimuli like histamine, protons, and potassium, and how substance P can decrease the pain threshold through an axon reflex.

10:01

🚪 Gate Control Theory Mechanism

This paragraph explains the gate control theory in detail, describing how touch receptors activated by rubbing an injured area can stimulate inhibitory neurons. These neurons release gamma-aminobutyric acid (GABA), which inhibits the transmission of pain signals at the spinal cord level. The summary highlights the process of how action potentials from touch receptors can inhibit the pain pathway, reducing the severity of pain perception.

15:03

🌱 Descending Analgesic System and Neuroanatomy

The fourth paragraph discusses the descending analgesic system, which involves various brain structures such as the periaqueductal gray matter, periventricular gray matter, locus coeruleus, reticular formation, and raphe nucleus magnus. It explains how these structures are involved in sending descending fibers to modulate pain at the spinal cord level, focusing on the release of neurotransmitters like norepinephrine and serotonin.

20:04

💊 Endogenous Opioids and Pain Inhibition

The final paragraph explains how the descending analgesic system releases chemicals similar to morphine, specifically endorphins and dynorphins, which are natural opioids produced by the body to reduce pain. It discusses how these chemicals inhibit the substantia gelatinosa of Rolando from sending action potentials, thereby decreasing pain perception. The paragraph also explores how the brain structures involved in the descending pathway are stimulated by the anterolateral system, sensory cortex, and limbic nuclei.

Keywords

💡Pain Modulation

Pain modulation refers to the body's internal mechanisms to regulate the perception of pain. It is central to the video's theme as it explains how the body naturally inhibits pain through chemical processes. The script discusses two types of pain modulation: the gate control theory and the descending analgesic system, both of which are crucial for understanding the body's response to pain.

💡Gate Control Theory

The gate control theory is a concept that describes how the nervous system filters and modulates the pain signals. It is a key part of the video's narrative, illustrating how touch receptors can 'close the gate' on pain signals. The script uses the example of rubbing a bumped head to explain how activation of touch receptors can alleviate pain by inhibiting the transmission of pain signals in the spinal cord.

💡Descending Analgesic System

The descending analgesic system is a neural pathway that originates in the brain and descends to the spinal cord to inhibit pain signals. The video script explains its importance in pain modulation, detailing how structures like the periaqueductal gray matter and the periventricular gray matter send signals to reduce the perception of pain. It is highlighted as a significant mechanism for the body's endogenous pain control.

💡Substance P

Substance P is a neurotransmitter involved in the transmission of pain signals. In the context of the video, it is released at the synapse point to stimulate second-order neurons, contributing to the sensation of slow pain. The script emphasizes its role in the slow pain pathway, particularly associated with C fibers, and how it can decrease the threshold for pain perception.

💡Glutamate

Glutamate is a neurotransmitter that plays a role in the fast pain pathway. The script explains that it is released by A-delta fibers at the synapse, causing faster and more intense excitation of second-order neurons. This leads to a quicker transmission of pain signals up the anterolateral system, illustrating the difference in speed and intensity between fast and slow pain pathways.

💡GABA

Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that reduces neuronal excitability. In the video script, GABA is mentioned as a chemical released by inhibitory neurons, which can decrease the transmission of pain signals in the substantia gelatinosa of Rolando. This illustrates the body's ability to naturally reduce pain through the gate control theory.

💡Periaqueductal Gray Matter (PAG)

The periaqueductal gray matter is a region in the midbrain involved in the modulation of pain and other functions. The script describes it as a key structure in the descending analgesic system, capable of stimulating other nuclei rich in norepinephrine and serotonin, which contribute to pain inhibition. It is activated by incoming pain signals and higher brain structures to modulate pain perception.

💡Endorphins

Endorphins are endogenous opioids that the body produces to reduce pain. The video script explains that inhibitory neurons stimulated by descending pathways release endorphins, which are similar to morphine in their pain-relieving effects. They are part of the body's natural pain modulation system and contribute to the overall theme of the video.

💡Dorsal Column Medial Lemniscus Pathway

The dorsal column medial lemniscus pathway is a neural pathway that carries touch and pressure sensations to the brain. The script explains its role in the gate control theory, where collaterals from this pathway stimulate inhibitory neurons, leading to a reduction in pain signals. It is an essential part of the body's mechanism for pain modulation.

💡Locus Coeruleus

The locus coeruleus is a nucleus in the brainstem that is rich in norepinephrine-producing neurons. The video script describes its role in the descending analgesic system, where it is stimulated by higher brain structures and contributes to pain modulation by releasing norepinephrine onto inhibitory neurons in the spinal cord.

💡Raphe Nucleus Magnus

The raphe nucleus magnus is a group of neurons in the brainstem and spinal cord that produce serotonin. In the context of the video, it is part of the descending analgesic system and is involved in the release of serotonin, which inhibits pain signals. The script emphasizes its role in the body's natural pain relief mechanism.

Highlights

Introduction to pain modulation as a critical aspect of the pain pathway.

Discussion on endogenous analgesic systems that inhibit pain through chemicals produced within the body.

Introduction of two types of pain modulation: gate control theory and the descending analgesic system.

Explanation of the gate control theory and its role in pain alleviation through touch receptor activation.

Mechanism of rubbing an injured area to reduce pain by activating different touch receptors.

Description of the substantia gelatinosa of Rolando and its importance in pain modulation.

Role of C fibers and A-delta fibers in pain transmission and the release of substance P and glutamate.

The effect of substance P in lowering the threshold for pain activation through axon reflex.

How the activation of touch receptors can inhibit pain signals through the release of GABA.

Overview of the descending analgesic system and its various neural structures.

Function of periaqueductal gray matter, periventricular gray matter, and locus coeruleus in pain modulation.

Importance of neurotransmitters norepinephrine and serotonin in the descending analgesic pathway.

The release of endogenous opioids like enkephalins and dynorphins for natural pain relief.

How the brain uses sensory input to modulate pain through the descending analgesic system.

Influence of higher brain structures like the limbic system and cerebral cortex on pain modulation.

Practical applications of understanding pain modulation for pain management and treatment.

Conclusion summarizing the importance of pain modulation mechanisms in the nervous system.

Transcripts

all right engineers in this video we're

gonna talk about the modulation of pain

it's equally as important as the pain

pathway itself if you guys haven't

already seen it please go watch the

video on the spinothalamic tract where

we talk about the anterior lateral

system well dip into a little bit again

in this video but we're not gonna do

into super depth alright

so pain modulation is super super

important we're gonna talk about two

different types of pain modulation and

they're all endogenous and meaning that

we all do it on our own inside of our

body we make the chemicals that are

necessary to be able to inhibit pain so

what are these two analgesic systems so

the two analgesic systems are the pain

modulating systems is actually going to

be regulate at two different levels so

there's pain modulating modulation what

are these two different pain modulations

okay one that we're going to talk about

first is the gate control theory and the

next one we're gonna talk about is the

descending analgesic system okay so

we're gonna talk about these two now

this gate control theory what's really

really important all right let's take a

scenario let's say I bumped my head

against something sharp or something

should hard and I hit it really hard and

it hurts right it induces pain because

of activating the a delts are activating

the C fibers right and it says that

information up to my cerebral cortex

helps you become aware of it and where

that pain is but there's a way that we

can kind of lessen the pain if any of

you I know that some of you guys have

definitely done this if you hit your

elbow against something or hit your head

against something what do you do

you rub it ah what why because it helps

to kind of alleviate some of the pain

how how does it do that okay we got to

think what are we doing when we hit our

head and then we start rubbing our head

we're activating different types of

touch receptors so in that situation

here let's say that we do that we have

the pain right so what's the painful

stimulus let's say here here's the pain

fibers and we're really gonna focus on

it can be see and it can be a delta but

we're mainly gonna be talking about this

with respect to the C fibers but do

remember the a delta R just is important

in this - just the C fibers control more

of this regulation okay so let's say

that there was pain right so there was

some type of painful stimulus or some

type of extreme temperature stimulus and

these were activating these fibers right

and from that it was activating me

peripheral processes then the central

processes and we said that the C fibers

particularly they go to a specific part

in the spinal cord remember the Rex

lamina we divided them into different

like partitions there was a specific one

right here it was called lamina - okay

and lamina - has a special nucleus right

here a special nucleus and right here is

this nucleus this guy is important

because in lamina - the rex lamina -

there's this special structure here

which is called the substantia gelatin

oza of Rolando and then from here we'll

activate some more axons and then cross

over here and move up right through the

anterior lateral system so we know that

there's a pain and temperature pathway

mainly regulated by the C fibers that

we're going to talk about going to

lamina - that's important and again what

is that lamina - a trex t' lamina - is

going to be called they call this the

substantia gelatin oza

of rolando holy crap

right so there's a lot of that one and

there's another one that I can't sign

apps on this is the main one there's

also the nucleus propria switch is in

Rex land on a three button main one here

substantial gelatin nose of Rolando so

now we know this pain pathway now

something I didn't discuss in the pain

pathway the actual video we talked about

the spinothalamic tract and I'm just

gonna mention it really quickly here

let's say here I have C fibers which are

represented here in red so here's my C

fibers and then over here which I want

to do in this baby blue is going to be

my a delta fibers okay they come into

the spinal cord right we know that these

guys come into the spinal cord and they

sign apps on some second-order neuron

and then crossover same thing over here

with the actual C fibers they come to

some second-order neuron and crossover

well the question is that we have to be

able to ask ourselves is what chemical

is actually being released in this

synapse

cuz that's important because it actually

determines a little bit of why fast pain

is fast and why slow pain is slow so

these C fibers are regulating slow pain

and they believe that the chemical that

is released at the synapse point is a

chemical called substance P okay

substance P is important in the synapse

to stimulate these second-order neurons

to go and actually send up through the

ascends through the anterior lateral

system but what about the chemicals with

the a delta fibers what chemicals are

they releasing to actually stimulate

this second-order neuron and then send

the action potentials upwards because

again they're going up and going up

here's the anterolateral system this

chemical that they're releasing into

that synapse is called glutamate and

this one causes excitation a lot faster

and a lot heavier this substance P is a

little bit of a slower activation

substance P you know what else is it's

important for it's also important

because you can release substance P

wherever there's stimulus remember the

stimulus for this was pain

and temperature these were the stimuli

here what's important here is that the

chemical factors that are actually a

cause that actually released like

they're from histamine and protons and

potassium and all that stuff what's

really important is that substance P can

actually be released down here too and

what it does is substance P through

what's called an axon reflex it can be

released out there where all these

chemical mediators are and what it can

do is it can actually decrease the

threshold for pain okay so we can

decrease the threshold needed to

activate the noisy acceptors and

transmit the pain that's really cool

okay so now that we understand that

these are the chemicals that are

released through those synapses for the

slow pain pathway at substance P for the

fast Bane pathway its glutamate let's

come back over here for a second we said

if we hit our head we're gonna send this

action potential upwards now I start

rubbing my head out hurt what am I going

to activate I'm gonna activate a bunch

of different touch receptors let's do

these in orange so here is going to be

some touch receptors let's say that it's

going to be some type of touch receptor

or coming from a pressure receptor

whatever right something like this these

get activated by me rubbing my head and

touching that right when it does that it

sends these action potentials into where

the poster Gary horn they go into the

posterior horn and where do these fibers

usually go for the pacinian corpuscles

the meissner's corpuscles all those guys

if you know they go into the dorsal

column and ascend upwards as the

fasciculus chrysella circuitous but

something's really cool they give off

little collaterals they give off little

collaterals that can come over and

actually stimulate a little inhibitory

neuron and we're gonna zoom in on that

and see how that actually works so we're

gonna come over to this cross-section of

Bionicle but I want you to remember that

whenever we hit our head we have a

painful stimulus a way that our body can

control that pain at the gate

the spinal cord is by rubbing that area

and by rubbing that area caressing the

area it can cause those fibers that are

going into the dorsal contract to give

off collaterals let's look at that so

let's say here was our pain fiber all

right it's bringing information into

substantial gel tones of Rolando and

then from here this guy is going to

cross over right we know it'll go

through the anterior commissure then we

said over here was going to be for the

touch for pressure maybe even a little

bit of stretch receptors or vibration

receptor stuff like that they're gonna

come in and they're going to go into the

dorsal column and ascend upwards right

they're going to go up eventually up to

the medulla where they'll become a part

of the medial meniscus eventually but

what happens is we said that these give

off collaterals they give up these

collaterals there's these little inter

neurons there's these little inter

neurons right here and this Rex lamina

right in again what was this Rex lamina

right here if we said it was Rex lamina

to where the substantiate gelatin oza

over Lata is if you have a lot of

stimulation due to the touch okay a lot

of touch stimulating these fibers what

are they going to do some of the action

potential is going to spill over into

this collateral when it spills over into

this collateral it's going to stimulate

this little inhibitory neuron when it

stimulates that inhibitory neuron guess

what happens that inhibitory neuron

starts releasing certain types of

chemicals what type of chemicals you ask

mainly gaba

okay so they start releasing chemicals

into the synapse called gamma amino

butyric acid and what that does is is

that inhibits it can inhibit two points

it can either inhibit the actual the

substantia gelatin oza where the nucleus

is the actual cell body is or it can

inhibit the actual synaptic terminal so

this actual synaptic bulb here of this

incoming neuron that's the central

process from the dorsal root ganglion

right either way if you inhibit that can

the action potentials that are being

sent from

his pain pathway these pain fibers this

is from pain and temperature right these

are being sent down this if you inhibit

this pathway what's going to happen to

the pain pathway the pain information

that's going over and up you're going to

decrease the action potentials if you

decrease the action potentials what's

that gonna do for the actual paint it's

going to decrease the actual severity of

the pain so this is going to try to

decrease pain perception I think that's

so cool

alright and this should make sense it

should make sense

okay so again with this part remember

that this part here was for the dorsal

column medial meniscal pathway and it

gives off little fibers collaterals that

stimulate these in little inhibitory

interneurons which can send released

certain types of inhibitory chemicals

like gaba to inhibit these neurons from

sending action potentials through the

anterolateral system modulating the pain

so that's called our gate control theory

alright sweet deal so we have that and

again recap it who is controlling this

dorsal column medial meniscal pathway

this was important because of their

collaterals so now we have to talk about

this descending analgesic system there's

so many different structures here that

are controlling this actual are

modulating the pain at the spinal cord

level a couple of them that we're gonna

talk about here is the perry a quid

ductile grey matter we're gonna talk

about this when we diet when we

illustrate them in the diagram we refer

to as PA G period echo dr. gray matter

another one is the peri ventricular

gray matter probably mark they says P V

G periventricular gray matter and then

there's another one here which is going

to be called the locus coeruleus and

some other ones here like the reticular

formation and we'll talk about another

one which is going to be the raphae

nucleus Magnus all these are really

really important gray matter structures

that I can control these descending

fibers so let's go ahead and talk about

those alright so a little bit of

neuroanatomy here's our thala my alright

so here's the thalamus now in between

the thalamus is actually going to be

this little cavity and this little

cavity here is called the third

ventricle so this is our third ventricle

there's pieces of gray matter right

around it so what do you think is called

peri ventricular gray matter fun simple

so these are really important so you

have the peri ventricular gray matter

they're gonna send these descending

fibers down now another thing what does

this structure right here

well this structure here is running

through the midbrain and it's the

continuation of the third ventricle

alright it connects it to the inferior

you there's the fourth ventricle this

structure right here is called the

cerebral aqueduct this blue structure

here well there's actually some nuclei

that are surrounding this cerebral

aqueduct so what do you think they're

called they're called the periaqueductal

gray matter and that's these little red

guys here alright so you have the

periaqueductal gray matter and the

periventricular green matter what these

guys do is they can send some fibers

down but they actually come over here

and they can activate a whole bunch of

other different types of nuclei what are

some of these other nuclei let's say

over here in the midbrain in the

midbrain you have these other structures

here and this is going to be these guys

are really really rich and

epinephrine they're rich in

norepinephrine and because they're rich

in norepinephrine these guys here this

is where we find what's called the locus

coeruleus all right now the locus

coeruleus is gonna get stimulated by the

periventricular grey matter the pair you

collect a grey matter right so again

what were their structure here this was

a periventricular grey matter and that's

when I here's the periaqueductal grey

matter they might be able to stimulate

this locus coeruleus right what else you

know there's other stimulations that

they can give to right here they have

the reticular formation the reticular

formation also has some special nuclei

that are located there and these guys

got a heck of a name this one right here

but actually the nuclei in this area is

called the para giganto celulares

reticular nuclei okay so you have the

pair of giganto cellular is particular

nuclei located within the reticular

formation these are important and again

why because these guys are actually

going to be rich in another type of

neurotransmitter which is called

serotonin okay so they're rich in what's

called serotonin also called you can

call it 5-hydroxytryptamine now there's

one more area which is also important

the perio doctor grey matter can also

give stimulation to these nuclei these

green nuclei are actually called the

raphe nucleus magnus so what would you

call these ones the Roth a nucleus

magnus these are some funky names right

but these are also going to be rich in

serotonin okay so you have the locus

coeruleus which is rich in

norepinephrine and you have the raphe

nucleus magnus and the pair giganto

sailors say layers reticular nuclei

they're rich in the serotonin

neurons now either way let's bring these

guys together okay and let's bring all

of these guys together down here because

they're gonna descend right to this area

here okay now when they descend they

actually go through a part like the

posterior lateral aspect over here in

the lateral white column and then they

come down and they synapse on those cell

bodies where the substantia gelatin oza

of rolando is so again all these fibers

can come down and sign apps right down

there and they can release what type of

chemicals accordingly if we're talking

about the locus coeruleus this is going

to be Noro epinephrine releasing neurons

and if we're talking about the pair

giganto solaris and the raphe nucleus

Magnus these are releasing what's called

5-hydroxytryptamine also known as Cerro

tonin now what happens here they go down

here and they secrete that serotonin in

that five hug us serotonin and

norepinephrine onto little inhibitory

neurons so how let's come over here and

see so since we've occupied a little bit

of this area let's occupy this other

area now okay so now we're going to come

over here and let's pretend for a second

that now we're going to have that pain

fibers are going to be coming in over

here now

so let's say here is going to be the

pain fibers coming in from this side

right activate it through some type of

painful stimulus comes in synapse is

here on the cell bodies of the

substantial gelatin nodes of rolando

cross over and then a ascends right

through the anterior lateral system or

the spinothalamic tract now over those

guys here we have the pair giganto

celulares from the actual reticular

formation we're gonna have the Roffe a

nucleus Magnus

and we're gonna have the locus coeruleus

fibers coming down here and releasing

what type of chemicals they're gonna be

releasing norepinephrine and

5-hydroxytryptamine you know what they

release it on there's little inhibitory

neurons little inhibitory neurons here

let's say it's right here this little

inhibitory neuron is going to be

stimulated by the norepinephrine and by

the 5-hydroxytryptamine and guess what

it's going to do it's gonna come over

here and it's gonna see create special

chemicals very very special chemicals

these chemicals that is going to be

secreting is going to inhibit the

substantia gelatin owes over Londo from

sending action potentials down and if

there's less action potentials being

sent up through this system then what's

going to happen to the pain perception

it's gonna decrease now what are these

chemicals that it's releasing and the

reason I'm telling you why it's why we

need to know these chemicals is because

you know there's chemical that we give

usually to people to help to alleviate

pain like morphine well these chemicals

that are being released here are very

very similar to morphine what are some

of these chemicals that they're

releasing there are releasing what's

called in Kathleen's endorphins and

another one called Dyne orphans all

these chemicals are basically like

natural opioids basically things are

basically our endogenous meaning that

you make them inside your own body

opioids

okay these are endogenous opioids so you

have a way to be able to reduce pain

okay now the question is that you guys

should have is we know how to modulate

pain but how do these nuclei know when

to fire that's important to ask yourself

how do these nuclei know when to fire

these action potentials downward to

inhibit these actual neurons that are

sending action potentials upward it's

the ones that are going up so remember

if we have the fibers coming up here

pretend we have the anterior lateral

system coming up right here so here's

your anterior lateral system ALS right

some of these fibers you know this

what's called the spine Omi's and

cephalic fibers the spine oh Mazen

cephalic fibers they were coming off of

that anterolateral system or the

spinothalamic tract they can stimulate

the periaqueductal gray matter so lots

of action potentials coming up - this

means that there's a lot of pain so that

means that you should stimulate this guy

to give descending pathways to help to

modulate that pain and then this should

make sense what else upper higher brain

structures what kind of structures so

some of the structures that can

influence these guys - periventricular

and the periaqueductal what are some of

them some of them is going to be the

actual limbic nuclei so some of the

limbic nuclei for example if you're with

a cingulate gyrus the insular cortex the

hypothalamus there's so many different

structures that can come down here and

regulate the periaqueductal gray matter

what else parts of the cerebral cortex

maybe even the sensory cortex the

sensory cortex can send down information

here so even the sensory cortex has the

ability to let the periaqueductal gray

matter know sensory cortex okay and then

let this peri o'clock the gray matter

know when to fire action potentials

downwards and these Perrigo dr. gray

matter and periventricular gray matter

they also can release in Cathal ins

alright so different types of endogenous

opioids so what are three ways that you

could actually stimulate this descending

pathway one is through this

anterolateral system where the spinal

attractive is coming off words you can

give off fibers what type of fibers

spino means in cephalic fibers what else

sensory cortex can also tell the gray

matter okay just fire some information

down other limbic nuclei like the

hypothalamus or the anterior in some

insular cortex or the cingulate gyrus

they can tell it also so it's a

beautiful beautiful system hi guys so

that pretty much covers everything that

we need to know about pain modulation I

really hope it made sense I truly do if

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