Lecture 13: SC Lateral Geniculate Nucleus

What is the function of the Suprachiasmatic Nucleus?

The Circadian rhythm

Recieve input from ipRGC [intrinsically photosensitive RGC]

What is the Circadian rhythm?

24 hr fluctations of biological processes

What is a topographic map in the superior coliculus?

Axons from RGCs in both eyes that are activated by the same object in the

visual field converge onto the same neurons in the SC

What is the layered structure in the SC?

Sensory neurons directly synapse onto motor neurons to control

movements, such as gaze and saccades.

What is in the Anterior (left & up) corner

Superficial layers

What is in the posterior (right & down) corner?

Visual,

Auditory,

Somatosensory input

Motor output

What is in the anterior / posterior (left & down) corner?

Intermediate & deep layers

What is in the posterior / anterior ( right & up) corner?

visual input

What is the purpose of the cortical visual subsytems?

They are required to consciously perceive objects

How do the the Cortical Visual Subsystems move information?

Retina — LGN [Lateral Geniculate Nucleus] — [Visual Cortex]

V1-V2-V3, V4,, V5

How does Blindsight work in moving information?

DOES NOT GO TO [ LGN or visual cortex]

Retina to SC (superior colliculus).  Can track/avoid objects subconsciously

Retina to SCN (suprachiasmatic nucleus)  circadian rhythm intact

Where does Blindsight signals from the retina NOT go?

Lateral Geniculate nucleus LGN —v1-v2-v3,v4,v5

The Receptive Field size in the Peripheral & RGC type?

• Convergence of Synaptic Input

• Large Receptive Field 

• M (Magno)-type

The Receptive Field size in the Central & RGC type?

• No or Less Convergence of Synaptic Input

• Small Receptive Field

• P (Parvo)-type

What are v3 and v4 used for?

Movement

What is V4 used for?

Color

What is the Inferotemporal Cortex (IT) used for? 

Complex Objects 

How many layers make up the LGN?

6

What do layers 1 and 2 contain?

• Magnocellular 

• Larger cells 

What do layers 3 to 6 contain? 

• Parvocellular 

• smaller cells 

What does each layer receive input from?

One Eye

The Retinal Inputs to LGN Layers

More descriptive Retinal Inputs to LGN layers