vis_webnotes2

Vis_webnotes2 - IX.B.2 Retinal Circuitry Look at Herman grid we will explain later No APs until ganglion Cells Light Light The cells of the retina

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
IX.B.2. Retinal Circuitry No APs until ganglion Cells Light Light The cells of the retina are arranged with the photoreceptors on the inside, so that light has to pass all the way through the retina before transduction can occur. After transduction occurs in the photoreceptors, information is passed through the neural circuit of the retina from the photoreceptors to the bipolar cells, and then to the ganglion cells which send their axons through the optic nerve to the brain. Information passing through the retina is modified by the lateral connections provided by horizontal and amacrine cells. Look at Herman grid –we will explain later
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
IX.B.2.a. "OFF" and "ON" pathways Excitatory synapse Note: the 2 pathways ultimately end in 2 different kinds of ganglion cells Off-biploar cell Off-ganglion cell On-ganglion cell On-biploar cell _______________ Off Pathway (signals dark with depolarization) Photoreceptor voltage change Amount of x-mitter released _______________ _______________ On-bipolar cell voltage change _______________ On-ganglion cell firing rate _______________ _______________ Sign-conserving synapse _______________ hyperpolarize decreases hyperpolarize decreases Shine light on On Pathway (signals light with depolarization) _______________ hyperpolarize _______________ Sign-reversing synapse _______________ decreases _______________ depolarize Excitatory synapse _______________ _______________ increases Difference due to x-mitter receptors mentioned in reading
Background image of page 2
Sign Reversing IX.B.2.b. Lateral inhibition
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Output of pink rod strongly hyperpolarized weakly depolarized weakly hyperpolarized Light 1 Light 2 from horizontal to TO rod = sign-reversing Light 1 only Light 2 only Light 2 from rod to horizontal is sign-preserving Light 1 Light hyperpolarizes black rod Rod to horizontal sign preserving horizontal cell hyperpolarizes Shine light 2 horizontal to rod sign-reversing rod depolarizes because hyperpolarization reversed = -1 -1 *1) ( *(-1/2) -1 + 1/2 = -1/2 = 1/2 Therefore if light is shone directly on a photoreceptor it will hyperpolarize. However light shone on a photoreceptor will cause depolarization of the neighboring photoreceptor.
Background image of page 4
This is partly what causes center surround organization Therefore if light is shone directly on a photoreceptor it will hyperpolarize. However light shone on a photoreceptor will cause depolarization of the neighboring photoreceptor. Therefore from the perspective of one photoreceptor, light shone on you Æ hyperpolarize Light shone surrounding you Æ depolarize IX.B.2.c Center-surround RFs
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
- + Example of the formation of a retinal ganglion cell receptive field from the input of 6 photoreceptors (in reality an RGC cell would receive more inputs) Photoreceptors from 6 different locations converge onto
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/10/2008 for the course NPB 100 taught by Professor Chapman during the Fall '08 term at UC Davis.

Page1 / 20

Vis_webnotes2 - IX.B.2 Retinal Circuitry Look at Herman grid we will explain later No APs until ganglion Cells Light Light The cells of the retina

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online