Module 6.1, 6.2 & 6.3- Visual System Anatomy

I. THE STIMULUS
        A. Getting the image to the retina
Most of the structures of the eyeball are involved in preparing the image that is reflecting visible light into the eye. The visible light range of the electromagnetic spectrum is the frequency of approximately 400-700nm. Humans perceive the shortest visible wavelengths as violet, medium short wavelenths is green; medium long wavelength is perceived as yellow and long wavelenght perceived as red. (see Figure 6.8 on page 160). Once the particular range of the electromagnetic energy is reflected off the image, the pattern of the reflected image enters the eyeball.
  
1. What role do the iris, pupil, lens and cornea (structures of the eyeball) play in getting the pattern of the reflection onto the photoreceptors of the retina?  (pag 156)

 2. In the illustration below draw in the placement of horizontal cells and amacrine cells.(page 169)
 3. Which cell axons leave the eyeball and what is this collection of axons called. Also, why is there a blindspot?






FRONT OF EYE BALL                                                                                BACK of EYE BALL

4. What is the role of the fovea? (pg 157) 
5. What is the functional significance of a midget ganglion cell?
6. What is convergence?


II. TRANSDUCTION (Retinal Processing)
  


IIIa. TRANSMISSION PATHWAYS IN THE EYE
   Ganglion Receptive Fields  (see lecture notes & pg 172)

IIIb. TRANSMISSION PATHWAYS IN THE BRAIN
Transmission of visual information actually begins in the retinal layers once the photoreceptors are stimulated. 
1. Trace the transmission pathway from when retinal cell axons leave the eyeball to the destination synapse of MOST of those cells in the LGN .(see pg 168 textbook and pg 134 Coloring Book)

 Lateral Geniculate Nucleus is located in the Thalamus.  (See PAGE 98 of Coloring Book)

IV. SENSATION, PERCEPTION and COGNITION

a. Receptive Fields (Sensation and Perception)
Use this site to help your understand the concept of Receptive Fields. You should understand the sections labeled
THE RETINA
RECEPTIVE FIELDS FROM THE RETINA TO THE CORTEX
You are not responsible for the third section- THE CELLULAR STRUCTURE OF THE VISUAL CORTEX.

b. Cogntion
Shape,
Color Perception
Motion Perception 

V. PUT IT ALL TOGETHER- Stimulus, Transduction, Transmission, Sensation, Perception & Cognition

If you are really understand this material, you should be able to easily read the following webites. Once you are comfortable reading the websites below, your next assignment will be to upload your version of the "Sensory Stories," in which you will be able to explain this sensory modality from start to finish  on a YouTube video.   More about the Sensory Stories assignment in class.

Put it all together site for Vision
 The following terms from this link will help you "put it all  together" in the story of the sensation of Vision.  USE THE FOLLOWING TERMS MARKED (*) FOR YOUR HOMEWORK ASSIGNMENT- VISION AND THE CLASS SCHEMA.

THE EYE
retina
*cornea
*lens
*photoreceptors
rods
cones
*amacrine
horizontal
*ganglion cells
*pupil
iris
first visual system synapse

THE TARGETS OF THE OPTIC NERVE
optic disk,
optic nerve
ganglion cell axons
*optic chiasm
*lateral geniculate nucleus of the thalamus
LGN receptive fields

THE VARIOUS VISUAL CORTICES
receptive fields of the cells of the retina
occipital lobe
*primary visual cortex
secondary visual cortex
*posterior inferior temporal cortex
*middle temporal cortex
*medial superior temporal cortex
ventral pathway
dorsal pathway