Transcript Memorize all the receptors!

• Muscle spindle
• Gamma motor neurons innervate the
contractile sides of intrafusal muscle
fibers
• “resets” the 1a afferents by
tightening up if IMF are slackened
• 1a afferent neurons (dorsal root
ganglion cell) innervate the noncontractile centers of intrafusal muscle
fibers
• Responds to changes in IMF
length (and therefore extrafusal MF
length)
• Prevents over-extension of muscles and
protect the joints
• Golgi tendon organ
• 1b afferent neurons winds through the
fibers
• When muscles contract, fibers are
tightened and 1b afferent terminals
are deformed and persistently
signals the muscle tension
• Prevents over-contraction of the muscles
and protect the tendons
• Saccule & utricle
• Signals static head position and
translational acceleration
• Saccule: vertical acceleration
• Utricle: horizontal acceleration
• The constant tug on the
otoconia by gravity keeps
populations of hair cells
persistently depolarized
and hyperpolarized,
depending on which side of
the striola they are located
• Signals head positional
information
• Also sensitive to
acceleration
• Semicircular canals
signal angular
acceleration (change
signals only)
• The cupula moves in
the opposite direction
of head turn
• Endolymph has higher
K+ concentration
rather than Na+
• Depolarized on one side of
the head, hyperpolarized on
the other side
Area 3b
• cortical columns in Area 3b
receives inputs from one
class of receptors from a
specific area of the body
Projections between structures
•
•
•
•
Layer 2/3 > cortex to cortex
Layer 4 > thalamus to cortex
Layer 5 > cortex to subcortical structures
Layer 6 > cortex to thalamus
primary somatosensory cortex: within-region (column) processing
the cortical column
layer-specific inputs
merging RA info. into SA info.?
dynamical into static?
Pacinian’s/Meissner’s into Merkl’s?
low-resolution into high-resolution?
SA2’s
Memorize all the receptors!
Mechanoreceptors
Transient / RA
Sustained / SA
Superficial
Meissner’s corpuscle
Merkel disk
- Prefer 20-50 Hz
- Low frequency vibrations &
slippage
- Small receptive field
- Prefer 5-15 Hz
- Fine shape
discrimination
- Smallest receptive field
Pacinian corpuscle
Ruffini ending
- Prefer 60-400 Hz
- High frequency vibrations
- Largest receptive field
- Direction of skin stretch
- Shape of hand/ objects
held in hand
- Large receptive field
Subcutaneous
Memorize all the receptors!
Other receptors
Transient / RA
Sustained / SA
Proprioceptive
Muscle spindle
Golgi tendon organ
- Changes in length of muscle
- Muscle tension
Semicircular canal
Saccule & utricle
- Angular acceleration of the
head
- Static position of the
head
- Translational
acceleration
Vestibular
True or False:
If a region of interest has greater fMRI BOLD signal,
the neurons in that region are firing more action
potentials.
True or False:
Generally speaking, action potentials come in
different sizes and shapes.
Short Answer:
Name the region that summates synaptic potentials
and “decides” whether to fire an action potential
True or False:
Different classes of mechanoreceptive signals are
integrated in the thalamus.
True or False:
The dorsal column medial lemniscal system crosses
contralaterally in the spinal cord before ascending to
the brain.
Short Answer:
Name the structure that signals translational
movement along the vertical axis.
Short Answer:
The anterolateral pathway transmits signals from the
____ and ____ modalities of somatosensation.
True or False:
Gamma motor neurons innervate the muscles that
move your bones.
True or False:
The hair cell inside the cupula on the left side of
your head depolarizes if you suddenly turned your
head to the right.
Short Answer:
What happens to the neuronal activity of 1a afferents
if I were to bend your arm inwards from an extended
position?
Short Answer:
Name 1 hypothesized function of surround
inhibition.
Surprise SAT question:
MERKEL DISK : PACINIAN CORPUSCLE ::
A.
B.
C.
D.
E.
Hair cell : nociceptor
Semicircular canal : utricle
Golgi tendon organ : muscle spindle
Medial lemniscus : cuneate fasciculus
Saccule : Ruffini ending