Transcript Diencephalon - People Server at UNCW

Understanding sensory-motor
integration
ORGANIZATION OF SENSORY
SYSTEMS: General perspectives
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Sensori-motor integration
External senses
Localize/Detect and monitor change
Less sensitive to unchanging stimuli
Tuned…sense modes
Organization of sensory systems
• Sense organs
• Receptors-specificity and transduction
– Receptive fields- and limitations
• coding- labeled lines vs pattern coding
• Adaptation and suppression
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Neural relays and recoding
Intra-modality sensory Convergence
Cortical representation/ perception
Sensory subsystems
The Visual System
Tracing the ccts of vision
Organization of sensory systems
• Sense organs
• Receptors-specificity and transduction
– Receptive fields- and limitations
• Adaptation and suppression
• coding- labeled lines vs pattern coding
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Neural relays and recoding
Intra-modality sensory Convergence
Cortical representation/ perception
Sensory subsystems
The organ of vision
The eye is like an SLR camera
Like a camera
• Lens-focus
• Iris-light control (aperture)
• Photoreceptors- transduction of light info
(Light sensitive film)
The lens-a small point of
interest
Like a camera-lens is curved
• Upside-down and inverted
Like a camera- Control of eye
movement also critical
Eye movement- 3 major types of
movement that can affect vision
Pursuit/tracking
Saccades
vergence
Organization of sensory systems
• Sense organs
• Receptors-specificity and transduction
– Receptive fields- and limitations
– Adaptation and suppression
– coding- labeled lines vs pattern coding
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Intra-modality sensory Convergence
Neural relays and recoding
Cortical representation/ perception
Sensory subsystems
Sensitivity and Limitations of the visual
system: visible light spectrum
Organization of sensory systems
• Sense organs
• Receptors-specificity and transduction
– Receptive fields and limitations
– Adaptation and suppression
– coding- labeled lines vs pattern coding
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Intra-modality sensory Convergence
Neural relays and recoding
Sensory subsystems
Cortical representation/ perception
The Iris
• Controls light exposure
Organization of sensory systems
• Sense organs
• Receptors-specificity and transduction
– Receptive fields- and limitations
– Adaptation and suppression
– coding- labeled lines vs pattern coding
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Intra-modality sensory Convergence
Neural relays and recoding
Sensory subsystems
Cortical representation/ perception
The retina-photoreceptive tissue
Visual field and retino-topic
organization
More on the retina
Photoreceptors
Rods and Cones
Receptive fields and Coding
RODS- dark/low illumination
sensitive to movement
peripheral vision
CONES- High illumination
sensitive to color
foveal vision
ROD CONE DISTRIBUTION
FOVEA
FOVEA and optic disc/blind spot
Foveal acuity
Retinal circuitry
NOTE:
• Light passes through ganglion cell layer,
and bipolar cell layer before striking
photoreceptors ( light transparent).
• Activation of photoreceptor activats cct in
reverse direction.
What accounts for Foveal acuity
Accounting for Foveal Accuity
1. Cone properties
2. Circuitry
Color Coding in cones
The Trichromatic Theory of
color
Receptive fields of Ganglion cells
Set up for sensory evoked
recording
Sensory convergence
Retinal photoreceptors
corresponding to Ganglion cell
receptive fields
Purpose of ganglion cell receptive
fields?
Lateral inhibition?
Lateral inhibition
Overlapping receptive fields
contribute to lateral inhibition
The center of one field may be the surround of another
Retina ganglion cell axons
coalesce
…and leave eye chamber to form
the optic nerve
From retina to cortex
Decussation at optic chiasm
Decussation-crossing over
..how does this work?
Partial decussation at optic chiasm
Decussation-crossing over
Not as simple as left and right eye
Decussation of visual field info
Temporal
retina
Nasal Retina
-Nasal Retinal Fibers Cross
-Temporal fibers do not
Retinotopic-Cortical
representation
-Left and right visual field info
-upside down
-Foveal dominance
Cortical Organization- LGN
input at layer 4
Vertical processing
Set up for sensory evoked
recording
Remember sensory
convergence
Receptive fields of neurons in
the PVC-orientation specificity
Orientation specificity
Orientation modules:Sensoryevoked recording studies
Modules- orientation specific
columns plus PVC “blobs”
Diagnosing/predicting visual
deficits
What happens if the entire PVC
is damaged?
Blind sight/ Superior Colliculi
• http://video.google.com/videosearch?hl=e
n&rls=GGIC,GGIC:200701,GGIC:en&ei=KD1bSsuNMJKKMec7EI&resnum=0&q=blindsight&um=1&ie=
UTF-8&sa=N&tab=wv#
• Other visual subsystems
-SCN
-Pineal gland
Suprchiasmatic NucleusCircadian Rhythms
Pineal Gland-”the third eye” and
Infradian rhythms
Secretor cells of the pineal
gland
Produce melatonin
OK… so what happens next?
VENTRAL STREAM
• Object Recognition
– Visual agnosias
– Prosopagnosia
– Anosagnosia
– http://video.google.com/videosearch?q=ramachandran+synesthe
sia&www_google_domain=www.google.com&hl=en&emb=0&aq
=4&oq=ramachandran#q=ramachandran+imposter&hl=en&emb
=0
prosopagnosia
• Dorsal Sream• WHERE/ CONTEXT/SPACE
– Balints
– Movement agnosia
– Visual Sensory neglect
Balint’s syndrome and
Simultagnosia
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Balint's syndrome is a neuropsychological disorder that results from damage to both parietal lobes 77. 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
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Spatial-visual agnosia
Visual hemilateral neglect
Putting the Visual World into
perspective: The DLPFC
Synesthesia and the DLPFC?
• http://science.discovery.com/videos/whensenses-collide-origins.html
• Synesthesia
• Check it out Dawgs!
Sensori-Motor Integration