~Chapter 14 - Lecture Section 14.3 Flashcards by Rebecca Temple

What is the function of pain?

Pain functions to warn us of potentially damaging situations

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Are some people unable to feel pain?

Yes. Some people are born with a congenital absence of pain, those who are often die fairly early due to infections from their acquired injuries.

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What is the Multimodal Nature of Pain?

Pain is often described as having sensory and emotional components. This might be because painful stimuli are so closely related to self-preservation

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What are sensory-component descriptions of pain?

Prickly, sharp, throbbing, dull, burning

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What are affective/emotional-component descriptions of pain?

Torturous, annoying, nagging

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What is Nociceptive Pain?

These free nerve endings have specialized receptors to signal impending damage to the skin, this is where something is getting to be damaging, and you’re able to remove yourself from the situation before you are damaged.

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What are free-nerve endings?

Nociceptors/pain receptors are free-nerve endings, they do not have specialized endings like Mechanoreceptors and are typically very small diameter axons

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What are the different specialized Nociceptors?

There are Nociceptors that are specialized for heat, different chemicals, excessive pressure, and cold temperatures.

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What is Inflammatory Pain?

Inflammatory Pain signals when you have done damage to tissues.

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With Inflammatory Pain, damaged cells that are ripped open due to some kind of trauma leak an “inflammatory soup” of ___, ___, ___, ___, ___, ___, and ___.

K+ // Serotonin // Brandykinin // Histamine // Prostaglandins // Leukotrienes // substance P

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K+, Serotonin, Brandykinin, and Histamine ___ Nociceptors.

activate

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Prostaglandins, Leukotrienes, and substance P ___ Nociceptors to further stimulation.

sensitize

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What is Neuropathic Pain?

Neuropathic Pain is caused by damage to the nervous system itself, and Nociceptor axons are aborantly stimulated without the sensation being present, causing you to feel pain.

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in things like inflammation related to Carpal Tunnel syndrome, ___ firing of neurons from spinal cord injury or Stroke, these Nociceptive pathways can become activated ___ any damage to the skin, and will produce pain.

abnormal // without

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What is the worst type of pain?

Neuropathic Pain is arguably the worst pain, because it is the hardest to treat because there is no tissue damage, and it doesn’t really serve an evolutionary advantageous role.

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Painful stimuli, once they come up the ___ and make their way to the ___, spread out to and activate multiple subcortical + cortical areas

Spinalthalamic track // Ventral Posterior Lateral Nucleus

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The Hypothalamus and Thalamus are ___ areas.

Subcortical

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___, ___, ___, ___, and ___, are all Telencephalic areas.

Somatosensory Cortex (S1, S2) // Insula // Anterior Cingulate Cortex // Hippocampus // Amygdala

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Where is the Insula located?

Buried underneath the outer shell of the Cortex

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Where is Anterior Cingulate Cortex located?

Deep in the Cortex, just over the Corpus Callosum

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What was the 1950’s Direct Pathway Model?

Stimulation of Nociceptor receptors → transmit signal to brain = feel pain

This is a purely bottom-up process that was a vast oversimplification

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There is tremendous ___ of Nociceptive Sensations.

Top-down modulation

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What is an example of Top-down modulation of Nociceptive Sensations?

There are many anecdotal reports that pain does not set in until the person realizes how injured they are.

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What is Phantom Limbs Syndrome?

Feeling a lost limb is still present, and sensation of pain without Nociceptor stimulation

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Painful sensations due to Phantom Limbs Syndrome can persist even when the subjects undergo surgery to lesion the afference all the way up to the ___. So it's not the afference, it's not the missing limb, it’s ___.

Dorsal Root Ganglion // Top-down modulation

Influences of Top-down modulation are ___ and ___.

multifaceted // complex

Who was the Gate Control Model proposed by?

Proposed by Melzack and Wall in 1965

What is the Gate Control Model?

Attempts to account for the many Top-down (thoughts, memories, expectations, emotions) influences on pain perception.

They suggested that the Gate Control System is located in the ___ of the ___. From the Spinalthalamic pathway, this is where these neurons are synapsing right off of the ___ of the Spinal Cord.

Substantia Gelatinosa // spinal cord // Dorsal Root

SG+ and SG- are innervated by ___.

L-Fibres

What are L-fibers?

Large diameter fibres with fast conduction velocities, which carry information about non-painful tactile stimuli from Mechanoreceptors.

L-fibres provide input/info to ___ and to ___.

SG- // Transmission cells

What are S-fibres?

Small diameter fibers with slow transmission velocity, and are associated with Nociceptors

S-fibres provide input/info to ___ and ___.

SG+ // Transmission cells

What is the Central Control?

Central Control captures all the Top-down inputs, and covers all the different ways in which Top-down can modulate the circuit.

What is a Transmission-cell (T-cell)?

The most important component of the Gate Control Model, which integrates all the inputs, so the activity level dictates the level of perceived pain.

When the Transmission Cells activity is pulled ___ a threshold from the SG- projection, you're ___ the gate on projection of pain.

below // closing

S-fibers (signals from Nociceptors) stimulation ___ T-cell activity.

increase

If there is ___ stimulation of the Nociceptors, it will ___ the level of the Transmission cell such that the threshold is exceeded and you're ___ the gate to pain.

too much // increase // opening

Projection from S-Fibre will activate ___ and so it will be ___ and ___, adding ___ to the T-cell

SG+ // +1 // +1 // 2

Projection from S-Fibre will activate ___ and so it will be ___ and ___, adding ___ to the T-cell.

SG+ // +1 // +1 // 2

Projection from the L-Fibre input activates ___, so its ___ and ___, ___ each other out.

SG- // +1 // -1 // cancelling

Stimulation of Mechanoreceptors is ___ increasing the activity of T-cells, and so it ___ be perceived as painful.

never // shouldn't

Imagine you have Nociceptors being stimulated such that the T-cell is receiving input from S and SG+, it can be cancelled by a strong enough ___, which ___ activates SG- to ___ activity in the T-cell.

Central Control // strongly // subtract away

What factors can effect the perception of pain?

Attention, distraction, emotions, and expectation

___ of the distraction task is important for affecting the perception of pain.

Salience

Did a burn patient find the Virtual reality immersion or video game more distracting? And why?

He reported that the Virtual reality immersion was much better than the video game due to its high Salience and distracting properties.

___ or ___ ___ can alter your perception of painful stimuli.

Positive // negative // affect

In the Cold-Press Task, when subjects viewed neutral images as they held their hand in the water, how long were they able to hold it there for?

80 seconds

In the Cold-Press Task, when subjects viewed distracting images that had a positive affect as they held their hand in the water, how long were they able to hold it there for?

120 seconds

In the Cold-Press Task, when subjects viewed distracting images that had a negative affect as they held their hand in the water, how long were they able to hold it there for?

70 seconds

___ of distracting stimulus is important for the perception of pain.

Emotional content

True or False: In a clinical setting, manipulating the patient’s beliefs can affect their perceived pain level

True

What is the Placebo Effect?

“The cure is all in your head”. It’s consistently reported that a portion of patients with pathological pain can experience relief from pills or injections with no active/medicinal ingredients.

The Placebo Effect is ___ in pain perception.

Salient

The best measures of the Placebo Effect for pain perception use ___.

remote control IV injections

In the experiments using remote control IV injections, what substances were used?

Saline (control) and/or Remifentanil.

In the experiments using remote control IV injections, when the nurse came in and told the patient they were changing the infusion in some way, this could either produce a ___, ___, or ___.

positive // negative // no expectation

When the Remafentinal was administered without the patient knowing, in other words, they had no expectation whether they were receiving a drug or not, their pain rating went ___ from ___ to ___. This is the ___ effect of the drug with ___.

down // 65 // 55 // true // no expectation

When the nurse told subjects they were going to receive a painkiller, this produced a ___ expectation, and the pain perception ___ to ___.

positive // fell // 39

The difference between the actual physiological effect of the Remifintinal with no expectation, and the drop due to the positive expectation is a ___.

Placebo Effect

When subjects were receiving the Remifentinal, but the nurse told them they were going to stop administering the drug and that they might feel more pain, this produced a ___ expectation, called a ___. They are still receiving the drug, but their pain perception ___ from ___ to ___, ___ the effect of the drug completely due to the ___ expectation.

negative // Nocebo Effect/Negative Placebo Effect // increased // 55 // 65 // cancelling out // negative

What kind of study was conducted where subjects were presented with painful stimuli under hypnosis?

PET study

Hypnotic suggestion to change the intensity of pain affected subjects rating of both ___ and ___.

pain intensity // unpleasantness

Hypnotic suggestion to change the intensity of pain altered activity in ___.

somatosensory cortex (S1)

Hypnotic suggestion to change the unpleasantness of pain ___ affect subjects rating of pain unpleasantness and ___ affect intensity.

did // did not

Is it possible to have something that feels intense but not unpleasant?

Yes

Hypnotic suggestion to change the unpleasantness of pain altered activity in ___.

Anterior Cingulate Cortex

What is one way to “hack” the Gate Control Model?

Through Stimulation-Produced Analgesia

Electrical stimulation of the ___ caused experimental animals to ___ normally painful stimuli (from tail pinch to abdominal surgery)

midbrain/periaqueductal gray region // ignore

It has been proposed that the electrical stimulation of the Central control activates ___ cells, which inhibit and reduces ___ activity to shut the Pain Gate in the Gate Control Model

SG- // Transmission-cell

Stimulation-Produced Analgesia involves/uses ___ pathway(s) as Opiate-Induced Analgesia

the same

Opiates such as ___, ___, and ___ are very effective Analgesic agents.

Morphine // Codeine // Fentanyl

True or False: Stimulation-Produced Analgesia and Opiate-Induced Analgesia work in the same way.

True

What are Endorphins?

An endogenously produced compound (produced naturally by the body)

Opiate Receptors are activated by opioid drugs/exogenous (e.g. opium, heroin, fentanyl), but also activated by ___.

Endorphins

Opioid receptors are ___ by Naloxone.

blocked

What is Naloxone?

Naloxone is a competitive antagonist for Opioid receptors which binds to the site and blocks binding of the Opioids. Naloxone is used more prevalently to revive Opioid overdoses

What happens if you administer Naloxone to an individual who has overdosed on Opioids?

Naloxone blocks the binding of Heroin and the Naloxone does not stimulate the receptor in the same way, and the effect of the Heroin is reduced.

During Stimulation-Produced Analgesia as well as several types of Placebo treatments work by inducing the ___ of Endorphins, the Endorphins bind to the Opioid receptors and this produces a ___ in pain.

release // relief

If before the electrical stimulation or Placebos are administered you give the experimental animals or human subjects Naloxone, the Naloxone can ___ the effects of the Placebos and Stimulation-produced Analgesia. The Endorphin is being blocked by Naloxone, causing an ___ in pain perception.

block // increase

It was previously believed that Endorphins would only have a ___ (hormone-like) effect. This is the type of Endorphin rush that runners or athletes will report, thought to be due to circulating Endorphins in the bloodstream

generalized

It has now been show that ___ of an Endorphin-mediated Placebo effect is ___.

localization // possible

When the Placebo cream was administered to the LH, the pain in the LH ___, and pain ratings in the other areas ___ decrease.

decreased // did not

The Placebo Effect is mediated by ___.

Endorphins

When the Placebo cream is applied to certain body parts, but is accompanied by a systemic injection of Naloxone, which is blocking the local effect of the Endorphins, what happens?

The pain perception is the same as the Controls/in the beginning.

What did Osborn and Derbyshire (2010) find when showing subjects videos horrific injuries?

Seeing horrific injuries induced “phantom pain” in 30% of observers. This subgroup also had more activation of S2 and Insula upon seeing the videos of injuries.

In Singer et al's., (2004) fMRI “electrocute my boyfriend” study, what did researchers see when female subjects received shocks or when they watched their partner receive shocks?

Similar brain areas were activated when female subjects received shocks or when they watched their partner receive shocks

In Singer et al's., (2004) fMRI “electrocute my boyfriend” study, subjects with higher empathy scores had ___ activation of the ___.

greater // Anterior Cingulate Cortex

The wince that you give when you see someone take a bad fall or injury, that phantom pain you are experiencing in some ways is real, because it is activating ___ parts of your brain as to when you are actually injured.

the same