Chapter 5

Bipolar Cells

Neurons in the retina that transmit signals from photoreceptors (rods and cones) to ganglion cells.

Blind Spot

The area in the retina where the optic nerve exits; it lacks photoreceptors, resulting in a gap in visual perception.

Color Constancy

The perception of colors as relatively constant under varying lighting conditions.

Color Vision Deficiency

A condition where individuals perceive colors differently than those with normal vision, often referred to as color blindness.

Cones

Photoreceptor cells in the retina responsible for color vision and visual acuity in bright light.

Fovea

The central part of the retina with the highest concentration of cones, crucial for sharp central vision.

Ganglion Cells

Neurons in the retina that receive input from bipolar cells and transmit visual information to the brain via the optic nerve.

Law of Specific Nerve Energies

A principle stating that the perception of a stimulus depends on the type of nerve fiber activated, not the stimulus itself.

Midget Ganglion Cells

A type of ganglion cell that has a small receptive field and is involved in high-acuity vision and color processing.

Negative Color Afterimage

An optical illusion where staring at a colored image causes a complementary color to appear when looking away.

Opponent-Process Theory

A theory of color vision that proposes color perception is controlled by opposing pairs of colors (red-green, blue-yellow).

Optic Nerve

The nerve that transmits visual information from the retina to the brain.

Photopigments

Light-sensitive molecules in photoreceptors that initiate the process of vision by changing shape in response to light.

Pupil

The adjustable opening in the eye that regulates the amount of light entering the retina.

Retina

The light-sensitive layer at the back of the eye that contains photoreceptors (rods and cones) and processes visual information.

Retinex Theory

A theory that explains color perception based on the brain's interpretation of light and color in relation to surrounding colors.

Rods

Photoreceptor cells in the retina that are sensitive to low light levels and are responsible for night vision.

Trichromatic Theory (or Young-Helmholtz Theory)

A theory that proposes color vision is based on three types of cones sensitive to red, green, and blue light.

Visual Field

The entire area that can be seen when the eyes are focused on a central point, including peripheral vision.

Aphantasia

A condition where individuals are unable to visualize images in their mind, affecting their ability to form mental imagery.

Astigmatism

A common vision condition caused by an irregular shape of the cornea or lens, leading to blurred vision at all distances.

Blindsight

A phenomenon where individuals with damage to the primary visual cortex can respond to visual stimuli without conscious visual perception.

Complex Cells

Neurons in the visual cortex that respond to specific orientations and movements of visual stimuli.

End-Stopped (or Hypercomplex) Cells

Neurons in the visual cortex that respond to particular lengths of stimuli and are sensitive to their endpoints.

Feature Detectors

Neurons that respond selectively to specific features of a stimulus, such as edges, angles, or movement.

Horizontal Cells

Neurons in the retina that facilitate lateral communication between photoreceptors and bipolar cells, enhancing contrast.

Hyperphantasia

An extreme ability to create vivid mental imagery, often described as having a "photographic memory" for images.

Koniocellular Neurons

Neurons located in the lateral geniculate nucleus that process color information and contribute to visual perception.

Lateral Geniculate Nucleus (LGN)

A relay center in the thalamus that receives input from the optic nerve and transmits visual information to the primary visual cortex.

Lateral Inhibition

A process where excited neurons inhibit the activity of neighboring neurons, enhancing contrast in visual perception.

Magnocellular Neurons

Large ganglion cells in the retina that are sensitive to motion and low-contrast stimuli, playing a role in detecting movement.

Parvocellular Neurons

Smaller ganglion cells in the retina that are involved in processing color and fine detail in visual stimuli.

Primary Visual Cortex (V1)

The area of the brain responsible for processing visual information, located in the occipital lobe.

Receptive Field

The specific region of sensory space in which a stimulus will affect the firing of a neuron.

Retinal Disparity

The difference in images between the two eyes, which contributes to depth perception.

Sensitive Period

A critical time frame during development when the brain is particularly receptive to certain stimuli, affecting learning and development.

Simple Cell

Neurons in the primary visual cortex that respond to specific orientations of edges and bars of light.

Strabismus

A condition where the eyes do not properly align with each other, often resulting in double vision or loss of depth perception.

V1 (Primary Visual Cortex)

The initial cortical area that processes visual information received from the lateral geniculate nucleus.

Dorsal Stream

The pathway in the brain responsible for processing the spatial location of objects and motion, often referred to as the "where" pathway.

Fusiform Gyrus

A region of the brain located in the temporal lobe, crucial for face recognition and processing complex visual stimuli.

Inferior Temporal Cortex

A part of the temporal lobe involved in the processing of complex visual patterns, including object and face recognition.

Motion Blindness

A condition where individuals cannot perceive motion, despite having intact visual acuity and perception of stationary objects.

MST (Medial Superior Temporal Area)

A region in the brain that is involved in processing visual motion and spatial awareness.

MT (Middle Temporal Area)

A brain region involved in the perception of motion and speed, playing a key role in the dorsal stream.

Prosopagnosia

A neurological condition characterized by the inability to recognize faces, often due to damage in the fusiform gyrus.

Saccades

Rapid, simultaneous movements of both eyes in the same direction, used to quickly shift focus from one point to another.

Secondary Visual Cortex

Areas of the brain that process visual information beyond the primary visual cortex, involved in higher-order visual processing.

Ventral Stream

The pathway in the brain responsible for object recognition and form representation, often referred to as the "what" pathway.

Visual Agnosia

A condition where individuals can see objects but cannot recognize or interpret them, often due to damage in the ventral stream.