D2 - Neuro Exam #1

Front 1

DIMENSIONS OF PAIN

Back 1

1. SENSORY-DISCRIMINATIVE
2. COGNITIVE-EVALUATIVE
3. AFFECTIVE-MOTIVATIONAL

Front 2

NEUROPATHIC PAIN

Back 2

PAIN ARISING AS A DIRECT CONSEQUENCE OF A LESION OR DYSFUNCTION AFFECTING
THE SOMATOSENSORY SYSTEM

Front 3

TYPES OF PAIN

Back 3

Nociceptive
Inflammatory hyperalgesia
Neuropathic hyperalgesia

Front 4

Pulpal Innervation

Back 4

Afferent:
- A-delta (myelinated): hydrodynamic pain. Located in plexus of Rashkow and dentinal tubules.
- A-beta (myelinated) - Located in apical third
- C fibers (unmyelinated) - most numerous, last to die in pulpitis. Located in the central pulp.

Autonomic sympathetic

Front 5

Application of cold causes severe, lingering pain

Back 5

Hyperalgesia. Symptomatic Irreversible Pulpitis.

Front 6

Percussion of the tooth causes moderate to severe pain

Back 6

Allodynia. Symptomatic Apical Periodontitis.

Front 7

Nociceptors are primary afferent neurons whose cell bodies are housed in...

Back 7

dorsal root ganglia or trigeminal ganglia

Front 8

DRG neurons are ________ neurons that project
bifurcated axons to both peripherally and centrally.

Back 8

unipolar

Front 9

Myelinated axons

Back 9

- mostly A-delta fibers.
- Thinly myelinated (diameter <6 m)
- Intermediate conduction velocities (<30 m/sec)
- ~30% of all nociceptors

Front 10

Unmyelinated axons

Back 10

- C-fibers
- Smallest axons (diameter 1 um)
- Slowest conduction velocities (<2.5 m/sec)
- ~70% of all nociceptors

Front 11

warm-receptors and sympathetic efferents also have
unmyelinated axons.

Back 11

warm-receptors and sympathetic efferents also have
unmyelinated axons.

Front 12

All nociceptors terminate ___ ____ ____ in
regardless of their myelination

Back 12

free nerve endings

Front 13

TRPV1 channels are non-selective cationic channels that are activated by...

Back 13

heat, capsaicin and protons.

Front 14

TRPV1 (VR1) is found in what types of fibers?

Back 14

C and A-delta fibers

Front 15

TRPV2 is found mainly in what fibers?

Back 15

A-delta

Front 16

Ionotropic receptors (ligand- gated channels):

Back 16

receptor is an integral part of the ion channel that it regulates; ligand binding changes channel gating (ATP, H+, glutamate, etc)

Front 17

Metabotropic receptors (Indirectly regulates channels):

Back 17

receptor is distinct from the ion channel it regulates; ligand binding activates second messenger cascades that alter channel gating (Bradykinin, prostaglandin, substance p, etc)

Front 18

A delta nociceptors can be classified into two types based on their responses to sustained stimuli.

Back 18

Type I AMH – are slowly adapting
Type II AMH – are rapidly adapting

Front 19

Axon Reflex-

Back 19

Activation of
one branch of a nociceptor by
a noxious stimulus results in
the antidromic invasion of
action potentials into adjacent
branches of the nociceptor,
which in turn causes the
release of vasoactive
substances from the terminals
of the nociceptor

Front 20

Dorsal Root Reflex

Back 20

If depolarization of primary
afferents at the central terminals are large enough, it
can generate the action potentials at the central
terminals that are conducted antidromically in the
primary afferent fibers, also resulting in the release of
vasoactive substances from the nociceptor terminals

Front 21

Sensitization

Back 21

a modulation of functional properties of the primary afferent nociceptor leading to a hyperexcitable state, which could result from modulation of cellular proteins leading to changes in ion channel activity with a subsequent increase in excitability

Front 22

Peripheral sensitization is
a neural substrate for...

Back 22

hyperalgesia

Front 23

Primary Afferent Nociceptor Signaling

Back 23

1. Transduction – a conversion of energy from the environment to a generator potential

2. Initiation – generator potential is converted into an action potential

3. Propagation – action potentials are conducted along the axon
4. Release – action potentials invading central or peripheral terminals cause the vesicular release of transmitters

Front 24

Mechanisms of Nociceptor Sensitization

Back 24

1. Direct actions on excitatory ion channels: ATP, glutamate and protons

2. Phospholipase C (PLC)-coupled receptors: bradykinin, ATP, and NGF

3. Adenylyl cyclase (AC)-coupled receptors: prostanoids, 5-HT, cannabinoids and opiates

4. Mitogen-activated protein kinase (MAPK) pathways

Front 25

The human spinal cord has 4 main regions or groups of segments:

Back 25

Cervical 8: back of head, shoulders, posterior and most of anterior of arm and hand.

Thoracic 12: trunk from below clavicle to top of pubis area; thoracic, abdominal and pelvic organs.

Lumbar 5: Anterior and inner surfaces of lower limbs; foot.

Sacral 5: Posterior and outer surfaces of lower limbs; lateral margin of foot and little toe; perineum; pelvic viscera.

Front 26

There is no lamina VI in the ______ segments.

Back 26

thoracic

Front 27

What laminae are considered the dorsal horn (site of sensory processing)?

Back 27

Laminae I-V

Front 28

Clarke’s column (origin of spinocerebellar tract; propriosensory processing) is found in...

Back 28

T1-L3.

Front 29

The main ascending tract for pain processing of somatic stimuli

Back 29

spinothalamic tract in the ventrolateral funiculus.

Front 30

superficial dorsal horn (laminae I, II) and lamina V are involved in processing...


Laminae III and IV processes...

Back 30

nociceptive information

innocuous stimuli.

Front 31

The dorsal horn:

Back 31

Integrator of afferent information

Types of neurons:
Excitatory, inhibitory
Interneuron, projection neuron

Front 32

The dorsal horn is composed of 5 types of neurons:

Back 32

1. Primary afferents
2. Inhibitory interneurons
3. Excitatory interneurons
4. Projection neurons
5. Fibers descending from the brain that modulate nociceptive processing in the spinal cord

Front 33

The most common scheme used to describe dorsal horn neurons is based on their response to cutaneous stimuli

Back 33

- Low threshold (LT) neurons receive input from non-nociceptive afferents.
- Wide Dynamic Range (WDR) neurons receive input from nociceptive and nonnociceptive afferents.
- Nociceptive specific (NS) neurons receive input from nociceptive afferents.

Front 34

trigeminal afferents synapse in the spinal nucleus of the trigeminal nerve, which has 3 subdivisions along the rostrocaudal axis:

Back 34

1. Subnucleus caudalis (Vc) extends from C2-C3 rostral to the obex. This is continuous with the spinal dorsal horn and is sometimes referred to as the medullary dorsal horn. Nociceptive afferents project mainly to Vc.


2. Subnucleus interpolaris (Vi) extends from the obex rostrally to the caudal pole of the facial nucleus.

3. Subnucleus oralis (Vo) extends from the caudal pole of the facial nucleus rostrally to the caudal end of the principle sensory nucleus (Vp).

Front 35

The Vc has functional and morphological similarities with the spinal cord _____ _____, and has been implicated as the essential area for orofacial nociceptive processing.

Back 35

dorsal horn

Front 36

Central sensitization:

Back 36

an increase in excitability of dorsal horn neurons in addition to peripheral sensitization

Front 37

secondary hyperalgesia

Back 37

an increased perception of pain from noninjured tissue

Front 38

Windup

Back 38

Central sensitization of the dorsal horn neurons that is evoked from C fiber activity which is responsible for temporal summation of “second pain”

Front 39

Temporal summation is the psychophysical equivalent of...

Back 39

windup

humans report increasing pain sensations to repetitive applications of noxious thermal or mechanical stimuli.

Front 40

Normally, inhibitory interneurons hyperpolarize the postsynaptic neuron by increasing ______ through GABA A receptors or increasing ______ following GABA B or opioid receptor activation.

Back 40

Cl- influx; K+ efflux

Front 41

Glial cells contribute to neuropathic and perhaps inflammatory pain by increasing release of _____ ______ which increase neuronal excitability causing hyperalgesia and allodynia.

Back 41

inflammatory cytokines

Front 42

The spinothalamic tract

Back 42

Axons bundled in the anterolateral part of the spinal cord relay somatic nociceptive and thermoreceptive information to brain

It is a crossed pathway

Front 43

The trigemothalamic tract

Back 43

Axons relaying all types of sensory information from the trigeminal nucleus to the thalamus


differential termination of nociceptive vs. mechanoreceptive afferent fibers within the trigeminal nucleus.

Front 44

a lesion in the lateral medulla would disrupt the nociceptive/thermoreceptive afferent fibers descending to the medullary trigeminal nucleus, without affecting the trigeminal _________ afferent fibers.

Back 44

mechanoreceptive

Front 45

Lateral medullary strokes (Wallenberg syndrome) affects pain sensitivity on the ________ face and the ________ body.

Back 45

ipsilateral; contralateral

Front 46

Visceral information travels in the ____ _______, separate from the STT.

Back 46

dorsal columns

Front 47

Ascending Nociceptive Pathways

Back 47

- Ventroposteriolateral (VPL) nucleus - Receives STT input

- Ventroposteriomedial (VPM) nucleus - Receives TTT input
Thus, VPL and VPM receive both innocuous and nociceptive signals.

- Ventroposterioinferior (VPI) nucleus - Receives principally nociceptive and thermoreceptive signals.

Front 48

S2 cortex

Back 48

Responsible for discriminative aspects of temperature and pain (less so for touch)

Front 49

Medial dorsal nucleus – ventral caudal part (MDvc)

Back 49

Projects to anterior cingulate cortex (ACC)- Entry point into the limbic system

ACC communicates with prefrontal cortex, as well as with rest of the limbic system

Responsible for affective and motivational aspects of pain.

Front 50

Posterior portion of ventromedial (VMpo) nucleus

Back 50

Responsible for some perceptual aspects of temperature and pain, autonomic/visceral responses to pain, emotional responses to pain.

Front 51

The existence of wide dynamic range neurons supports the...

Back 51

convergence theory

Front 52

Central pain

Back 52

a type of neuropathic pain that results from injury to the CNS.

Front 53

Lesions in S2 cortex

Back 53

pain and temperature perception

Front 54

Lesions in S1 cortex always alter

Back 54

tactile perception

Front 55

Features of fMRI

Back 55

1. Indirect measure of neural activity
2. Non-invasive
3. Largely available technology
4. Good spatial resolution (~1cm3)
5. OK temporal resolution (seconds)
6. Unlimited replications
7. Can evoke claustrophobia

Front 56

Features of PET

Back 56

1. Indirect measure of neural activity
2. Invasive (radioactive isotope injection)
3. PET scanners less common, more expensive
4. OK spatial resolution (~10 cm3)
5. Poor temporal resolution (minutes)
6. Limited by radioactive exposure
7. Can measure things fMRI cannot

Front 57

Features of MEG

Back 57

1. Direct measure of neural activity - Magnetic fields associated with electrical fields
2. Non-invasive
3. Technology is uncommon, expensive
4. Good spatial resolution (1-10 cm3)
5. Great temporal resolution (< 1msec)
6. Unlimited replications