Chapter 10 Midterm 3 Flashcards
What is haptic feedback?
You push something and get feedback on how much pressure you need to move it
What are the 8 steps of movement in order?
- You get visual information required to locate the target
- The frontal lobe motor areas plan the reach and command the movement
- The spinal cord carries the information to the hand and coordinates the fingers
- The motor neurons carry the message the the muscles of the the hand and forearm
- The sensory receptors in the fingers send message back to the sensory cortex saying that we grasp the cup
- The spinal cord carries the sensory information to the brain
- The basal ganglia judges the grasp forces and the cerebellum corrects movement errors
- The sensory cortex recieves the message that the cup has been grasped
Where is the sensory area in relation to the motor areas?
Right beside
Is all movement generated by the motor cortex related on sensory cortex information?
No that’s too simple
How do you initiate a motor sequence, as in what does the prefrontal cortex, premotor cortex, and motor cortex do?
The prefrontal cortex plans the movement
the premotor cortex organizes the movement sequences
the motor cortex produces specific movements
What does the motor cortex do?
responsible for force of movement and coordinates movement- lesions in motor cortex makes you weaker
Also sends general programs to the brain stem and spinal cord
What outside of the motor cortex coordinates movement?
the spine
What does a unilateral lesion in the premotor cortex do?
it impairs performance on tasks requiring both hands
What is bloodflow an indicator of?
an indicator of neural function)
Do we have equal amounts of blood flowing to all areas of brain all the time?
no, areas stimulated get more blood
When does bloodflow increase in primary somatosensory and primary motor cortex?
It increases when you have simple movement like using a finger to push a lever
When does bloodflow increase in the premotor cortex?
When participants form a sequence of motions, ex: clap, then spin, then clap
When does bloodflow increase in the prefrontal, temporal, and parietal cortex?
through complex movement (ex: trying to put finger through maze)
What is the initial function of the brain?
To make movements
What is penfields homunculus?
Its a figure showing you the amount of sensory and motor cortical tissue that is devoted to particular areas of the body
Who made the homunculus? How?
HP kentelly, took pieces of paper that penfield put on the brain to see what parts of the body got stimulated and made a structure
How did they find out how much of the brain was devoted to different body parts?
electrical stimulation of the motor cortex which elicted movement of body parts which corresponded to the map of the body
Why do chimpanzees have faces upside down in humunculus? But humans are upside right?
Mistake, penfield made an error
Why did penfield make error of faces being upside right?
Because the map was made using atypical people, people with seizures and epilepsy and tumours which had maps come out different than what it actually was.
What do cats use whiskers for?
They use whiskers to estimate whether they know they’ll get in places, if whiskers touch, they know they’ll get switched
What do rodents with epilepsy have different in their homonculus? How does it effect the image of the homonculus?
The spaces between the different body parts overlap, so some cortical tissue goes to other places, this makes the original picture much more fuzzier so it’s not accurate the homonculus its like a picasso painting
What’s a mistake in the homoculus?
He drew the right hand side of the body on the right hemisphere of the brain, should be left hand side of the body on the right hemisphere of the brain
What is the elephants biggest cortical devoted area?
the trunk
What is intracortical microstimulation?
When you put tiny little electrodes down into the brain in a grid structure and the intersects of the grid into layer 5, and apply tiny current
What is layer 5 in the brain?
the output layer of the motor cortex
How does the current being applied to layer 5 neurons create twitches?
You stimulate output neurons, the axons go to spinal cord, makes synaptic connection with alpha motor neurons that interact with muscle groups to drive twitches
Why was 40 milliseconds of stimulation used in intracortical stimulation?
Because they believed longer stimulation would cause seizures
What did michael granziano do?
Used 100 to 200 milliseconds of stimulation - about the same length of tie it takes the animal to normally move
This made animals do natural movements
What does long stimulation of premotor cortex do? (like what actions)
Ascend or descend, jump
Reaching to clasp
Defensive posture/expression
What does long stimulation of the primary motor cortex do?
hand control in lower body space
hand control in ventral body space
masticate/lick
What experiment did Teskey do to determine whether Graziano was correct in that the motor cortex also coordinates movement?
Stimulated the rats forelimb area for long periods of time and got complex movements such as elevate, advance, grasp and retract
How did they confirm that the motor neuron is involved in the coordination of movements?
They cooled the grasp area (the rostral forelimb area) in the forelimb of the rat brain and then stimulated the rat again with long duration ICMS and found significant errors in the grasping of the rat. So we know that the motor cortex is involved with coordination of movements.
What other experiment involving monkeys proves that motor cortex neurons take part in planning and executing movements as well as regulating movement force and duration?
When the monkey flexes its wrist to rotate a lever attached to a weight more neural activity is found when the weight is heavier and before they go to rotate the lever,
What experiment showed that neurons are maximally responsive to movements in a particular direction?
When a monkey moves lever in different directions, there is maximal neuron activity when it moves forward to 180 and minimal when it’s backwards to 0, shows that the firing of neurons in the motor cortex is attuned to movement
Where does the corticospinal tract descend from?
from the motor cortex the brain stem, at the pyramidal protruision (at brain stem) it defecates across and moves down the opposite side to the spinal cord
What are the two tracts the corticospinal tract breaks off into?
The lateral corticospinal tract, anterior corticospinal tract
What does the lateral corticospinal tract do?
Moves limbs and digits on the bodys right side
What anterior corticospinal tract do?
moves muscles at the body’s midline
Is there corpus collosum for finger movements?
No
How are the interneurons and motor neurons arranged?
so
that the more
lateral neurons
innervate the
more distal
parts of the
limbs.
What does the lateral corticospinal tract synapse with?
Synapse with interneurons and motor neurons that innervate muscles of the limbs and digits
Where do the interneurons project?
Project to motor neurons