PSYCH 240 LEC 4 (VISUAL SYSTEM)

Retina

• Light-sensitive layer of tissue at the back of inner eye that converts light into nerve signals for the brain.

  • Consists of:

    • Rods & Cones (Photoreceptors) in back of eye

    • Ganglion (Output) to the brain

    • Bipolar (Bridge)

Rods & Cones (Photoreceptors)

Rods

• Concentrated in the periphery

• Detect brightness

Cones

• Concentrated in the fovea

• Detect color

• 3 types

  • Green

  • Red

  • Blue

Ganglion Cells

• Type of neuron

• Transmit processed visual information from the eye to the brain

Neuron

• Potential

  • The difference in charge inside vs outside axon

  • Potential to do work

Dendrites

• Branched, tree-like extensions of a nerve cell (neuron) that receive chemical and electrical signals from other cells and carry them toward the cell body

Soma

• Neuron cell body

• Central part of a neuron, contains the nucleus and keeps the cell alive

Axon

• Long, slender projection of a nerve cell (neuron) that conducts electrical impulses away from the cell body to other neurons, muscles, or glands.

Resting Potential

• At -70 mV

• Cell's plasma membrane when it is not sending signals

Action Potential

• Generating action potential = Fire

• Pas

Threshold

All-or-None

Propagation

Refractory Period

Neurotransmitters

Synapses

Electrochemical Transmission

Summation

Receptive Field

Firing Rate

Excitation

Inhibition

Center-Surround

M-Cells

P-Cells

Magnocellular Layers

Parvocellular Layers

Thalamus

Lateral Geniculate Nucleus (LGN)

Cerebral Cortex and Lobes

Primary Visual Cortex (V1)

Simple Cells

Complex Cells

Hypercomplex Cells

What Pathway (Ventral Stream)

Where Pathway (Dorsal Stream)

Temporal Lobe

Parietal Lobe

PET Scanning

Kohler Experiment

Population Coding