NEUR3101 Lecture Notes - Lecture 16: Reticular Formation, Biceps, Brainstem
Our receptors capture only a tiny fraction of the information in the environment, and we are
consciously aware of only a small proportion of these sensory inputs
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Input from one single receptor often cannot encode information due to ambiguity
across fibre pattern encoding
Integrating with sensory modality
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Limb position is estimated based on inputs from different types of proprioceptors
(muscle spindles, Golgi tendon organs, joint receptors), tactile receptors and vision
Integrating across different receptor types and sensory modalities
○
Receptors responses are variable, over longer observation time noise is averaged out
Integrating over time
○
Error correction based on history (learning)
Comparing the inputs with memories of previous sensory experience
○
Proprioceptive system is calibrated by vision
Recalibrating the system
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Information from single receptors is unreliable and ambiguous. The nervous system processes
sensory signals by:
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What does a receptor signal?
The motor control system can use all classical senses to initiate and guide the movement
depending on biological context (starting from chemotaxis in more primitive animals)
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The motor control system has access to sensory information which we are not aware of and which
doesn't create conscious percept
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Proprioception (position sense), kinaesthesia (movement sense) and the vestibular sense
are predominantly motor
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related, although they also contribute to perception
○
Vision usually dominates perception if there is a mismatch between sensory inputs
from different modalities
Vision, hearing, touch play significant role in motor control
○
Sensory systems may have dedicated information processing stream devoted specifically to motor
control, as motor control may require different coordinate system as perception and it requires
different kind of sensory information
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Which senses are used in motor control?
"what" pathway (object recognition)
Allocentric or object
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centred frame of reference
High resolution form of vision (shape, colour, texture)
V4 contains neurons responding selectively to the colour of visual stimulus without regard
to its direction of movement. Part of the ventral stream
○
"where" pathway (spatial vision)
Motion analyses (direction, speed), positional relationship between objects
Egocentric or viewer
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centred frame of reference
Damage to this area causes Cerebral Akinetopsia
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inability to appreciate (see)
movement of objects. Has difficulty to judge movement of approaching car or people,
difficulty to pour tea because fluid seemed to be "frozen"
Middle temporal area (MT) contains neurons responding selectively to the direction of
movement. Part of the dorsal stream
○
About 25 areas have been identified to be predominantly or exclusively visual in function
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Ventral and dorsal streams of extrastriate cortex
Sensorimotor control
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voluntary movement, feedback
and feed-forward control
Monday, 11 June 2018 8:04 PM
Lecture 16 Page 1
Document Summary
Sensorimotor control - voluntary movement, feedback and feed-forward control. Our receptors capture only a tiny fraction of the information in the environment, and we are consciously aware of only a small proportion of these sensory inputs. Information from single receptors is unreliable and ambiguous. Input from one single receptor often cannot encode information due to ambiguity across fibre pattern encoding. Integrating across different receptor types and sensory modalities. Limb position is estimated based on inputs from different types of proprioceptors (muscle spindles, golgi tendon organs, joint receptors), tactile receptors and vision. Receptors responses are variable, over longer observation time noise is averaged out. Comparing the inputs with memories of previous sensory experience. The motor control system can use all classical senses to initiate and guide the movement depending on biological context (starting from chemotaxis in more primitive animals) The motor control system has access to sensory information which we are not aware of and which doesn"t create conscious percept.
