Week 4.11 - The Embodied Brain Flashcards
What are the methods of testing causality in the neural circuitry of the C. elegans?
- Genetic manipulation - Targeted cell elimination - Optogenetic stimulation
Saccades are…
rapid eye movements to direct attention to discrete locations
Smooth pursuit enables us____
to lock our gaze on a moving target.
Which reflex is activated in response to the movement of the visual field?
Optokinetic Reflex follows the visual field (and Nystagmus brings the eye back)
Which of the following areas is not involved in vestibular processing?
Hippocampus, Vestibular nuclei, Thalamus, Cerebellum.
Hippocampus
Adaptation of the vestibular-ocular reflex is associated with which brain area?
Cerebellum (primarily LTD in Purkinje cells and Parallel Fibers)
What are sensorimotor behaviors? Give a few examples
Sensorimotor behaviors are those with an ongoing relationship between sensory inputs and motor outputs.
When a motor behavior implies the sensory feedback in the loop consisting of the motor environment and the body.
Examples: VOR, Optokinetic reflexes, grasping an object (force on hand specifies tactile feedback)
What are saccades?
A saccade is a quick eye motion between points of fixation.
Example: While reading, one performs saccades in between fixating on specific words. We do not move our eyes continuously, but discontinuously.
What is the optokinetic reflex (OKR)?
OKR is a reflex that locks your eye with an object in a moving field (a tree passing by the train window).
When you ‘snap back’, this is called a ‘nystagmus’. It is a reflex that can normally be suppressed.
> See this video <
What is the function of the semicircular canals and the vestibular system?
They measure the rotational acceleration of the head.
The vestibular system is a sensory system that provides information about motion, head position, and spatial orientation.
The semicircular canals are filled with endolymph. The endolymph flows through the canals and moves the cilia. When the cilia are pushed in one (preferred) direction, the hair cells will be depolarized. If the cilia are pushed in the opposite direction, the hair cells will be hyperpolarized.
Why is C. elegans a good biological model?
- It has a simple nervous system
- Tractable for study
How can you define sensorimotor integration?
Sensorimotor integration is a process that produces task-specific motor output based on selective and rapid integration of sensory information from multiple sources.
A nasal-temporal eye movement is a movement of the eye in the ____ plane.
horizontal
Which ocular muscles are activated when you move your eyes to the right?
The right lateral rectus and left medial rectus
Which cranial nerves innervate the eyes?
Four cranial nerves innervate the eyes. One sensory nerve (optic II) and three motor (trochlear IV, abducens VI, oculomotor III) nerves
The visual system temporarily shuts down during a _____ movement
saccadic
What does a tonic neuron do in an eye circuit?
Maintains eye position, the ‘step’ signal.
A bursting neuron in an eye circuit most likely encodes____
the ‘pulse’, the signal for saccades.
An omnipause neuron in an eye circuit____
stops firing during an eye movement
Rotational acceleration of the head is picked up by____
semicircular canals
The translational movement of the head is picked up by____
otoliths
What is proprioception?
Through proprioception, we perceive the position and movement of our bodies. It depends on the relationship between the nervous system and the muscular tissue.
Actin and myosin are involved in ____
muscle contraction
Retinal ganglion cells respond to _____
edges
What is the role of substantia nigra and superior colliculus in saccadic movement?
During a saccadic movement, the superior colliculus is activated and substantial nigra (which inhibits the superior colliculus) is inhibited.
An experimenter applies mechanical pressure to the skin of a C. elegans.
Outline the general (neural) map from pressure application to behavior.
Give a definition for the vestibulo-ocular reflex (VOR).
VOR is a reflex that stabilizes the gaze during head movements. The eyes move to the opposite direction of the ‘vestibular world’.
What are some of the differences between optokinetic and vestibulo-ocular reflexes?
In the case of OKR, the visual world is moving, and the eyes follow. Something visually or optically drives the eye movement.
In the case of VOR, the vestibular world is moving and the eyes move in the opposite direction in order to stabilize the gaze.
What happens to the optokinetic reflex (OKR) if the vestibular world is moved to the opposite direction of the visual world?
OKR increases
What happens to the vestibulo-ocular reflex (VOR) if vestibular and visual worlds move in the same direction?
VOR decreases
What determines our internal model for estimating physical reality (position)?
A combination of vestibular and somatosensory (proprioceptive) information
Is the following statement true or false?
Sensorimotor integration can be modified to change the behavioral response.
True
For example, Purkinje cells in the cerebellum can be trained via the inferior olivary nucleus to alter eye movement (by changing the behavior of the vestibular nucleus).
