Understanding sensory-motor integration

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Understanding sensory-motor integration
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ORGANIZATION OF SENSORY SYSTEMS General
perspectives

• Sensori-motor integration
• External senses
• Localize/Detect and monitor change
• Less sensitive to unchanging stimuli
• Tunedsense modes

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Organization of sensory systems

• Sense organs
• Receptors-specificity and transduction
• Receptive fields- and limitations
• coding- labeled lines vs pattern coding
• Adaptation and suppression
• Neural relays and recoding
• Intra-modality sensory Convergence
• Cortical representation/ perception
• Sensory subsystems

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The Visual System
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Tracing the ccts of vision
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Organization of sensory systems

• Sense organs
• Receptors-specificity and transduction
• Receptive fields- and limitations
• Adaptation and suppression
• coding- labeled lines vs pattern coding
• Neural relays and recoding
• Intra-modality sensory Convergence
• Cortical representation/ perception
• Sensory subsystems

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The organ of vision
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The eye is like an SLR camera
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Like a camera

• Lens-focus
• Iris-light control (aperture)
• Photoreceptors- transduction of light info
  (Light sensitive film)

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The lens-a small point of interest
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Like a camera-lens is curved

• Upside-down and inverted

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Like a camera- Control of eye movement also
critical
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Eye movement- 3 major types of movement that can
affect vision
Pursuit/tracking Saccades vergence
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Organization of sensory systems

• Sense organs
• Receptors-specificity and transduction
• Receptive fields- and limitations
• Adaptation and suppression
• coding- labeled lines vs pattern coding
• Intra-modality sensory Convergence
• Neural relays and recoding
• Cortical representation/ perception
• Sensory subsystems

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Sensitivity and Limitations of the visual system
visible light spectrum
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Organization of sensory systems

• Sense organs
• Receptors-specificity and transduction
• Receptive fields and limitations
• Adaptation and suppression
• coding- labeled lines vs pattern coding
• Intra-modality sensory Convergence
• Neural relays and recoding
• Sensory subsystems
• Cortical representation/ perception

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The Iris

• Controls light exposure

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Organization of sensory systems

• Sense organs
• Receptors-specificity and transduction
• Receptive fields- and limitations
• Adaptation and suppression
• coding- labeled lines vs pattern coding
• Intra-modality sensory Convergence
• Neural relays and recoding
• Sensory subsystems
• Cortical representation/ perception

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The retina-photoreceptive tissue
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Visual field and retino-topic organization
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More on the retina
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Photoreceptors
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Rods and Cones
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Receptive fields and Coding
RODS- dark/low illumination sensitive to
movement peripheral vision CONES- High
illumination sensitive to color foveal vision
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ROD CONE DISTRIBUTION
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FOVEA
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FOVEA and optic disc/blind spot
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Foveal acuity
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Retinal circuitry
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NOTE

• Light passes through ganglion cell layer, and
  bipolar cell layer before striking photoreceptors
  ( light transparent).
• Activation of photoreceptor activats cct in
  reverse direction.

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What accounts for Foveal acuity
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Accounting for Foveal Accuity 1. Cone
properties 2. Circuitry
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Color Coding in cones
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The Trichromatic Theory of color
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Receptive fields of Ganglion cells
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Set up for sensory evoked recording
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Sensory convergence
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Retinal photoreceptors corresponding to Ganglion
cell receptive fields
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Purpose of ganglion cell receptive fields?
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Lateral inhibition?
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Lateral inhibition
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Overlapping receptive fields contribute to
lateral inhibition
The center of one field may be the surround of
another
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Retina ganglion cell axons coalesce
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and leave eye chamber to form the optic nerve
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From retina to cortex
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Decussation at optic chiasm
Decussation-crossing over ..how does this work?
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Partial decussation at optic chiasm
Decussation-crossing over Not as simple as left
and right eye Decussation of visual field info
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Temporal retina
Nasal Retina
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-Nasal Retinal Fibers Cross-Temporal fibers do
not
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Retinotopic-Cortical representation
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-Left and right visual field info-upside
down-Foveal dominance
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Cortical Organization- LGN input at layer 4
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Vertical processing
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Set up for sensory evoked recording
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Remember sensory convergence
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Receptive fields of neurons in the
PVC-orientation specificity
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Orientation specificity
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Orientation modulesSensory-evoked recording
studies
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Modules- orientation specific columns plus PVC
blobs
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Diagnosing/predicting visual deficits
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What happens if the entire PVC is damaged?
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Blind sight/ Superior Colliculi

• http//video.google.com/videosearch?hlenrlsGGIC
  ,GGIC2007-01,GGICeneiKD1bSsuNMJKKMe-c7EIresnu
  m0qblindsightum1ieUTF-8saNtabwv

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• Other visual subsystems
• -SCN
• -Pineal gland

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Suprchiasmatic Nucleus-Circadian Rhythms
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Pineal Gland-the third eye and Infradian rhythms
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Secretor cells of the pineal gland
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Produce melatonin
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OK so what happens next?
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VENTRAL STREAM

• Object Recognition
• Visual agnosias
• Prosopagnosia
• Anosagnosia
• http//video.google.com/videosearch?qramachandran
  synesthesiawww_google_domainwww.google.comhle
  nemb0aq4oqramachandranqramachandranimpost
  erhlenemb0

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prosopagnosia
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• Dorsal Sream-
• WHERE/ CONTEXT/SPACE
• Balints
• Movement agnosia
• Visual Sensory neglect

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Balints syndrome and Simultagnosia

• Balint's syndrome is a neuropsychological
  disorder that results from damage to both
  parietal lobes77. Clinically, it includes three
  main symptoms simultanagnosia (the inability to
  see more than one object at a time) optic ataxia
  (the fixation of gaze with severe problems in
  voluntarily moving fixation) and optic apraxia
  (the inability to reach towards the correct
  location of perceived objects)78
• Spatial-visual agnosia

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Visual hemilateral neglect
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Putting the Visual World into perspective The
DLPFC
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Synesthesia and the DLPFC?

• http//science.discovery.com/videos/when-senses-co
  llide-origins.html
• Synesthesia
• Check it out Dawgs!

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Sensori-Motor Integration