2007 Sensory Physiology

Retina

  • sensory information passes from the rods and cones to the bipolar cells, which also generate graded potentials
    • bipolar cells receive input from rods or cones (but not both)
    • the degree of convergence between photoreceptors and bipolar cells varies throughout the retina (less convergence in the fovea, more on the periphery --- i.e., greater acuity in the fovea)
    • photoreceptors can release either excitatory or inhibitory neurotransmitter
  • bipolar cells subsequently stimulate ganglion cells, which generate action potentials
  • horizontal and amacrine cells modulate activity in the bipolar and ganglion cells; in particular, they produce lateral inhibition, and they contribute to the complexity of ganglion cell receptive field properties

Retina structure

S&G Figure 10.29

  • the retina consists of 3 nuclear layers (described along the light path from front to back) which contain:
    1. INNER - the ganglion cell bodies whose axons form the optic nerve
    2. MIDDLE - bipolar cells
    3. OUTER - the photoreceptors (rods and cones)
  • in between the primary cell layers are two plexiform layers (also called inner and outer), which contain the amacrine and horizontal cells, respectively

 

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