PSYC 212 Lecture Notes - Lecture 19: Intraparietal Sulcus, Premotor Cortex, Body Schema
6 Nov 2018
School
Department
Course
Professor
Rubber hand illusion
Congruent tactile and visual information can make you believe that a
rubber hand is your own hand
§
Associated with activity in bilateral premotor cortex and left
intraparietal sulcus
§
When people still have a limb and feel as though it's missing
They feel as though their hand (or other body parts) aren't
really in that exact location
□
§
Putting the left (or right) hand out of vision, and replace it with a
rubber hand
Experimenter will stroke the hand and the rubber hand in the
same spot
□
The participant will then close their eyes and will be asked to
point to where they think their hand is
□
It was found that participants will point to where the rubber
hand, believing that their real hand is actually there
□
§
Skin temperature of the "abandoned" limb drops
§
In the brain
§
○
Body schema
Bimodal neurons in intraparietal region
Respond to touch in its somatic receptive field (sRF)
§
Respond to visual stimuli in its visual receptive field (vRF) - mostly
targets moving the sRF direction
§
Change their receptive field after tool use: related to sense of "body
ownership" of the tool
§
○
•
Haptic perception
Knowledge of the world that is derived from sensory receptors in skin,
muscles, tendons, and joints, usually involving active exploration
○
Exploratory research: a stereotypical hand movement pattern used to
contact objects in order to perceive their properties; each exploratory
procedure is best for determining one or more object properties
Example: to determine roughness of an object, use lateral motion
§
○
The what system of touch
Geometric properties of objects are most important for visual
recognition
§
Material properties of objects are crucial for haptic recognition
Two-dimensional pictures of objects are recognized easily
visually but poorly haptically
□
§
Haptic search
Task: recognize presence of material properties that are
presented haptically to the fingers with a special device
□
Do some material properties "pop out"?
Yes: rough among smooth, hard among soft, cool among
warm, edged surfaces among smooth surfaces
®
No: horizontal lines among vertical lines
®
□
"pop out" stimuli for vision and touch are different□
§
○
The where system of touch
Knowing where objects are in the environment using only touch
perception
Example: finding snooze button on alarm clock in the morning□
§
Frame of reference: the coordinate system used to define locations
in space
Egocentric: the center of reference frame used to represent
locations relative to the body or hand
□
Allocentric: "true" location in Euclidian space
We do not use this
®
□
§
Our frame of reference is somewhat distorted
§
Experiment
Participant placed in front of circles, blindfolded□
Had to place pencils diagonally in all of these circles□
§
○
•
Pain
Temperature perception
Thermoreceptors
Sensory receptors that signal information about changes in skin
temperature
§
Two distinct population of thermoreceptors: warmth fibers, cold
fibers
§
Body is constantly regulating internal temperature
§
Thermoreceptors respond when you make contact with an object
warmer or colder than your skin
§
They don't have any fancy endings
Free nerve endings: pain, heat and cold□
§
○
•
Pain perception
Specificity theory
Only responds to noxious stimuli
That can potentially damage the skin□
§
Found to be true
§
○
Intensity theory
Only respond to stimuli that will damage the body
§
○
Nociceptors
Sensory receptors that transmit information about noxious
stimulation that causes damage or potential damage to skin
§
Two groups
A-delta fibers: intermediate sized, myelinated sensory nerve
fibers that are transmit pain and temperature signals
□
C fibers: narrow diameter, unmyelinated sensory nerve fibers
that transmit pain and temperature signals
□
§
Painful events have two stages - quick sharp pain (A-delta fibers_
followed by throbbing sensation (C fibers)
Difference in speeds is due to myelination□
§
○
In patient without A-delta fibers
Similar to Ian Waterman
§
Can't feel touch (vibration)
§
Perception of temperature is preserved
§
"Limbic touch" is preserved
§
Not congenital, immune reaction to a virus
§
Patient will get brushed with a soft brush on the forehead and arm
Will say she feels it on the forehead and report it being
pleasant
□
Will says she doesn't feel it on the arm but still report it being
pleasant
□
§
○
Spinothalamic pathway
Carries most of the information about skin temperature and pain
(slower)
§
First synapse in the dorsal horn of the spinal cord
§
Crosses immediately to the contralateral side
§
Second synapse in the thalamus and then reaches the cortex (S1 and
other areas)
§
Crosses at the segmental level, whereas the dorsal column pathway
crosses side at the level of the medulla
§
Brown squared syndrome
Any partial lesion of the spinal cord will produce tactile deficits
directly below the lesion, and thermoalgesic deficits on the
other side
□
§
○
Referred pain
Pain perceived at another location than the site of the painful
stimulus, typically pain in an internal organ is "projected" onto a
dermatome
§
Caused, in part, by convergent projections from the skin and internal
organs
§
○
Gate control theory (1965)
Touch can inhibit pain through the activation of inhibitory inter-
neuron
§
Rubbing a body part that has experienced pain, helping the pain go
away
§
Provided an alternative to the intensity and specifictiy theories
§
The overall pattern activity of neurons
§
○
Primary and secondary sensory cortices (S1 and S2)
Involved in the sensory dimension of pain, e.g., intensity, location,
etc.
§
○
Anterior cingulate cortex (ACC)
Involved in the affective dimension of pain, e.g., unpleasantness,
desire to remove the arm, etc
§
Hypnotic suggestions to reduce pain unpleasantness reduces pain
unpleasantness, but not pain intensity
Reduced activity in S1 and ACC□
§
Hypnotic suggestions to reduce pain intensity reduces pain intensity
and unpleasantness
Reduced activity in ACC□
§
Lesions of the ACC can sometimes be performed to relieve pain that
is difficult to treat otherwise
§
Patients feel the pain but are no longer bothered by it
§
Also activated in the anticipation of pain (yellow = anticipation,
organe = actual pain)
§
Also activated when observing pain in other people (empathy?)
§
And when you threaten a rubber hand!
§
○
Pain asymbolia
Condition in which pain is experienced without unpleasantness
§
○
•
Lecture 19(20)
Thursday, March 29, 2018
1:00 PM
Rubber hand illusion
Congruent tactile and visual information can make you believe that a
rubber hand is your own hand
§
Associated with activity in bilateral premotor cortex and left
intraparietal sulcus
§
When people still have a limb and feel as though it's missing
They feel as though their hand (or other body parts) aren't
really in that exact location
□
§
Putting the left (or right) hand out of vision, and replace it with a
rubber hand
Experimenter will stroke the hand and the rubber hand in the
same spot
□
The participant will then close their eyes and will be asked to
point to where they think their hand is
□
It was found that participants will point to where the rubber
hand, believing that their real hand is actually there
□
§
Skin temperature of the "abandoned" limb drops
§
In the brain
§
○
Body schema
Bimodal neurons in intraparietal region
Respond to touch in its somatic receptive field (sRF)
§
Respond to visual stimuli in its visual receptive field (vRF) - mostly
targets moving the sRF direction
§
Change their receptive field after tool use: related to sense of "body
ownership" of the tool
§
○
•
Haptic perception
Knowledge of the world that is derived from sensory receptors in skin,
muscles, tendons, and joints, usually involving active exploration
○
Exploratory research: a stereotypical hand movement pattern used to
contact objects in order to perceive their properties; each exploratory
procedure is best for determining one or more object properties
Example: to determine roughness of an object, use lateral motion
§
○
The what system of touch
Geometric properties of objects are most important for visual
recognition
§
Material properties of objects are crucial for haptic recognition
Two-dimensional pictures of objects are recognized easily
visually but poorly haptically
□
§
Haptic search
Task: recognize presence of material properties that are
presented haptically to the fingers with a special device
□
Do some material properties "pop out"?
Yes: rough among smooth, hard among soft, cool among
warm, edged surfaces among smooth surfaces
®
No: horizontal lines among vertical lines
®
□
"pop out" stimuli for vision and touch are different
□
§
○
The where system of touch
Knowing where objects are in the environment using only touch
perception
Example: finding snooze button on alarm clock in the morning
□
§
Frame of reference: the coordinate system used to define locations
in space
Egocentric: the center of reference frame used to represent
locations relative to the body or hand
□
Allocentric: "true" location in Euclidian space
We do not use this
®
□
§
Our frame of reference is somewhat distorted
§
Experiment
Participant placed in front of circles, blindfolded
□
Had to place pencils diagonally in all of these circles
□
§
○
•
Pain
Temperature perception
Thermoreceptors
Sensory receptors that signal information about changes in skin
temperature
§
Two distinct population of thermoreceptors: warmth fibers, cold
fibers
§
Body is constantly regulating internal temperature
§
Thermoreceptors respond when you make contact with an object
warmer or colder than your skin
§
They don't have any fancy endings
Free nerve endings: pain, heat and cold□
§
○
•
Pain perception
Specificity theory
Only responds to noxious stimuli
That can potentially damage the skin□
§
Found to be true
§
○
Intensity theory
Only respond to stimuli that will damage the body
§
○
Nociceptors
Sensory receptors that transmit information about noxious
stimulation that causes damage or potential damage to skin
§
Two groups
A-delta fibers: intermediate sized, myelinated sensory nerve
fibers that are transmit pain and temperature signals
□
C fibers: narrow diameter, unmyelinated sensory nerve fibers
that transmit pain and temperature signals
□
§
Painful events have two stages - quick sharp pain (A-delta fibers_
followed by throbbing sensation (C fibers)
Difference in speeds is due to myelination□
§
○
In patient without A-delta fibers
Similar to Ian Waterman
§
Can't feel touch (vibration)
§
Perception of temperature is preserved
§
"Limbic touch" is preserved
§
Not congenital, immune reaction to a virus
§
Patient will get brushed with a soft brush on the forehead and arm
Will say she feels it on the forehead and report it being
pleasant
□
Will says she doesn't feel it on the arm but still report it being
pleasant
□
§
○
Spinothalamic pathway
Carries most of the information about skin temperature and pain
(slower)
§
First synapse in the dorsal horn of the spinal cord
§
Crosses immediately to the contralateral side
§
Second synapse in the thalamus and then reaches the cortex (S1 and
other areas)
§
Crosses at the segmental level, whereas the dorsal column pathway
crosses side at the level of the medulla
§
Brown squared syndrome
Any partial lesion of the spinal cord will produce tactile deficits
directly below the lesion, and thermoalgesic deficits on the
other side
□
§
○
Referred pain
Pain perceived at another location than the site of the painful
stimulus, typically pain in an internal organ is "projected" onto a
dermatome
§
Caused, in part, by convergent projections from the skin and internal
organs
§
○
Gate control theory (1965)
Touch can inhibit pain through the activation of inhibitory inter-
neuron
§
Rubbing a body part that has experienced pain, helping the pain go
away
§
Provided an alternative to the intensity and specifictiy theories
§
The overall pattern activity of neurons
§
○
Primary and secondary sensory cortices (S1 and S2)
Involved in the sensory dimension of pain, e.g., intensity, location,
etc.
§
○
Anterior cingulate cortex (ACC)
Involved in the affective dimension of pain, e.g., unpleasantness,
desire to remove the arm, etc
§
Hypnotic suggestions to reduce pain unpleasantness reduces pain
unpleasantness, but not pain intensity
Reduced activity in S1 and ACC□
§
Hypnotic suggestions to reduce pain intensity reduces pain intensity
and unpleasantness
Reduced activity in ACC□
§
Lesions of the ACC can sometimes be performed to relieve pain that
is difficult to treat otherwise
§
Patients feel the pain but are no longer bothered by it
§
Also activated in the anticipation of pain (yellow = anticipation,
organe = actual pain)
§
Also activated when observing pain in other people (empathy?)
§
And when you threaten a rubber hand!
§
○
Pain asymbolia
Condition in which pain is experienced without unpleasantness
§
○
•
Lecture 19(20)
Thursday, March 29, 2018 1:00 PM
Document Summary
Congruent tactile and visual information can make you believe that a rubber hand is your own hand. Associated with activity in bilateral premotor cortex and left intraparietal sulcus. When people still have a limb and feel as though it"s missing. They feel as though their hand (or other body parts) aren"t really in that exact location. Putting the left (or right) hand out of vision, and replace it with a rubber hand. Experimenter will stroke the hand and the rubber hand in the same spot. The participant will then close their eyes and will be asked to point to where they think their hand is. It was found that participants will point to where the rubber hand, believing that their real hand is actually there. Respond to touch in its somatic receptive field (srf) Respond to visual stimuli in its visual receptive field (vrf) - mostly targets moving the srf direction.
