Somesthesis
http://www.youtube.com/watch?v
=qoiaUV7fGEI
Top-Down Processing
• Information guided by mental processes– Starts in the brain– Construct perceptions through prior experience
and expectation
Bottom-up Processing
• Begins with sensory information– Works up to brain’s integration of sensory
information
Processing Examples:• I go to the doctor’s office to get shots. I hate getting shots.
This is the worst. I’m going to have the worst time ever. Why do we have to do this today. My parents tricked me – they said we were going to Wendy’s and hotdamn, I love that place… but no this is not Wendy’s, we have to first stop off and get these shots, this is the worst I hate it I hate it I hate it… I get the shot, and I was right, it is the worst thing ever. It hurts. Ow Ow Ow Ow.– Top-down or bottom-up?
• I go to the doctor’s office to get a shot. The doctor sticks me. Ow. It sucks. This is the worst ever.– Top-down or bottom-up?
But it’s not as easy as having a cone or a rod, or a taste bud…
• There are 4 types of touch, but only pressure has an identifiable receptor site.
1. Pressure2. Warmth3. Cold4. Pain
– Why not hot?
PRESSURE has its own receptors - 0ther skin sensations are just combos of the other four
(pressure, pain, cold, warm)
• Stroking alternating pressure = tickle– You can’t tickle yourself… the brain understands foreign vs. domestic
terrorism• Repeated gentle stroking of pain = itching• Touching cold and pressure = wet
– think of touching really cold and dry metal• Stimulating cold and warm = hot
• But what could hot also be? Top-down or bottom-up?
• http://www.youtube.com/watch?v=sxwn1w7MJvk - Rubber Hand Illusion (which two senses are at play here, and what’s this called?)
Somesthesis• Fancy word for touch
sense• HUMUNCULUS
– Motor and sensory cortex together
• Where are they located in the brain?
• Broken down into two parts– Kinesthesis– Vestibular sense
Kinethesis
• Sense of position and movement of body parts– Enabled by receptors in your joints, tendons,
bones, ears, and skin
• Monitors your head’s (and thus body’s) position and movement– Based off equilibrium in inner ear– Semicircular canals contain vestibular sacs which
connect to the cochlea
Vestibular Sense
Pain
• Your body’s way of saying something has gone wrong.
• Combines bottom-up and top-down– How? Think of examples from beginning of class…
In case you need it: The Pain Circuit
• Sensory receptors (nociceptors) respond to potentially damaging stimuli
• Send impulse to the spinal cord• Passes the message to the brain• Interprets the signal as pain
Gate Control Theory
• Draw it out!– Nociceptors– Endorphins– Distracted stimulation and control– Selective attention
• Pain meds and the Placebo Effect:• http://www.youtube.com/watch?v
=R4PON6Chgug
Phantom Limb
• Mirror box solution/experiment– http://www.youtube.com/watch?v=gc3CmS8_vUI