Perception Study Guide
1) Be prepared to incorporate the stories from MWM into each of the disorders below
2) Know the roles of both the anterior parietal lobe (aka somatosensory cortex) and the posterior
Anterior Parietal Lobe (front) – contains the somatosensory cortex, which encodes
sensory information having to do with touch (pressure pain and temperature)
Posterior Parietal Lobe (back) – contains the motor cortex, which encodes
information for how our limbs should move
Be able to describe the purpose of the sensory homunculus.
i.The homunculus is a figure that shows what proportions of the somatosensory
cortex are devoted to each body part.
That is why the hands, face and mouth
are huge compared to the back, hips, feet, etc…
The more cortical space that
a body part takes up, the more neurons are used to handle information from
that body part and the more sensitive that body part is to touch (same is true
for the motor cortex and fine motor movement)
3) What are the three ways that we get a sense of balance (and body position)?
The three ways that we get a sense of balance is through the processes of
proprioception, the vestibular system using the inner ear and vision.
Be able to describe proprioception – what are the pathways involved in knowing
where our body parts are without peeking (feedback loop)?
Include the specific
pathways from muscles/tendons to brain.
i.Proprioception is the sense we have of where the different parts of our body
are at all times.
It gives us constant feedback so that we are about to control
how are limbs move in space without having to look at them.
ii.Pathways of Proprioception – there is a feedback loop that is involved with
Our muscle spindles and the tendon golgi from each of our
limbs sends information to the position the limb (can tell if the muscles are
stretched, stretched muscles/tendons send out action potentials).
information travels up the dorsal route of the spine on the same side of the
body that receives it from the dorsal root ganglion, where the neurons are
collected from the body, until it reaches the brain stem, where the information
switches side so that information from the left side of the body goes to the
right side of the brain and visa versa.
From there, the information travels to
the thalamus and then on to the somatosensory cortex, where the information
is processes, and then behind it where proprioception is processed.
Information for how the person wants the limb to move is then sent out from
the motor cortex, down the ventral route, back down to the muscles and
tendons, which then send information back up.
For Christina (the woman without proprioception), the information got
up to her anterior parietal lobe, where it was blocked by something
For syphilis patients, the ganglions get damaged so they lose feeling in
Know the vestibular system (and what occurs in the ears)
i.The vestibular system, which gets its signal from the inner ear, helps us know