From Retina to Cortex

Physiology of the Eye

The study of the functions and structures of the eye.

Pupil

Entry point of light into the eye.

Iris

Adjusts the size of the pupil based on light conditions.

Cornea & Lens

Structures that focus light onto the retina.

Accommodation

The process by which ciliary muscles adjust the lens shape for focusing on objects at different distances.

Photoreceptors

Specialized cells in the retina that detect light.

Rods

Photoreceptors sensitive to dim light, absent in the fovea.

Cones

Photoreceptors responsible for daytime vision, with three types for different wavelengths (long, medium, short).

Retina

The layer of tissue at the back of the eye containing photoreceptors and retinal ganglion cells (RGCs).

Retinal Ganglion Cells (RGCs)

Neurons that transmit visual information from the retina to the brain.

Receptive Fields (RFs)

Areas of the retina that influence the activity of a ganglion cell.

On-Centre, Off-Surround RFs

Ganglion cells excited by light in the centre and inhibited by light in the surround.

Parasol Ganglion Cells

RGCs sensitive to movement and flicker.

Midget Ganglion Cells

RGCs sensitive to colour and detail.

Lateral Inhibition

A process that enhances contrast and is crucial for edge detection.

Lateral Geniculate Nucleus (LGN)

A thalamic structure that processes visual signals from the retina before they reach the cortex.

Magnocellular Cells

LGN cells that process motion and flicker.

Parvocellular Cells

LGN cells that process colour and detail.

Koniocellular Cells

LGN cells that process blue-yellow colour contrast.

Experiment Examples

Research methods using visual stimuli to study specific visual pathways.

Primary Visual Cortex (V1)

The area of the cortex primarily dedicated to processing visual information.

Retinotopy

The mapping of visual field locations onto specific areas in V1.

Hubel & Wiesel Experiments

Research that identified orientation selectivity in the visual cortex.

Plasticity in Visual Development

The concept that early experiences shape the development of the visual cortex.

Dorsal Stream (Where)

The visual processing stream responsible for spatial awareness and movement.

Ventral Stream (What)

The visual processing stream responsible for object identification and recognition.

Example of Motion-Colour Interaction

The Suchow & Alvarez (2011) illusion demonstrating how motion affects colour perception.

Neural Plasticity & Critical Periods

The idea that early experiences shape neural pathways and that there are critical periods for development.

"Use it or lose it" Principle

The concept that lack of exposure to certain stimuli during critical periods can lead to a lack of response to those stimuli later.

Hierarchy of Processing

The increasing complexity of visual processing from the retina to higher brain areas.