Chapter 9 Flashcards
(39 cards)
Blind Spot
The area on the retina where the optic nerve exits, which lacks photoreceptors. This creates a small region in the visual field where no visual information is detected.
Example sentence: The blind spot is located approximately 15 degrees temporal to the line of sight.
Blob
Regions in the primary visual cortex (V1) involved in color processing. Blobs contain neurons that are specifically responsive to different wavelengths of light.
Example sentence: Blobs play a critical role in color perception and are essential for distinguishing between different hues.
Color Constancy
The ability to perceive colors consistently across different lighting conditions. It ensures that the perceived color of objects remains relatively constant despite changes in illumination.
Example sentence: Color constancy allows us to recognize a red apple as red whether we see it in bright sunlight or under artificial light.
Cone
Photoreceptors in the retina responsible for color vision and high spatial acuity. Cones are most concentrated in the fovea and function best in bright light.
Example sentence: Cones are essential for seeing fine details and distinguishing between different colors.
Cortical Column
Vertical columns of neurons in the cortex that process similar types of information. Each column is considered a fundamental processing unit in the brain’s cortical architecture.
Example sentence: Cortical columns help organize and integrate sensory information to facilitate complex cognitive functions.
Dorsal Stream
A visual pathway that processes spatial location and movement of objects. Known as the “where” pathway, it extends from the primary visual cortex to the parietal lobe.
Example sentence: The dorsal stream guides actions such as reaching for an object or avoiding obstacles in the environment.
Extrastriate (Secondary Visual) Cortex (V2–V5)
Visual areas beyond the primary visual cortex (V1) involved in higher-order visual processing. These areas specialize in different aspects of visual perception, such as motion (V5/MT) and color (V4).
Example sentence: The extrastriate cortex is crucial for complex visual tasks like recognizing faces and interpreting visual scenes.
Facial Agnosia
The inability to recognize familiar faces, typically resulting from damage to the fusiform face area in the temporal lobe. This condition is also known as prosopagnosia.
Example sentence: Individuals with facial agnosia may have difficulty identifying family members or friends by their faces.
Fovea
A small, central pit in the retina densely packed with cones. It provides the highest visual acuity and is crucial for tasks requiring detailed vision, such as reading.
Example sentence: The fovea allows us to focus on fine details and perceive sharp images of objects in our central vision.
Geniculostriate System
The main visual pathway from the retina to the primary visual cortex (V1) via the lateral geniculate nucleus (LGN) of the thalamus. It is essential for conscious visual perception.
Example sentence: The geniculostriate system plays a key role in relaying visual information from the eyes to the brain for processing.
Homonymous Hemianopia
Loss of vision in the same half of the visual field in both eyes, often due to brain damage. This condition typically results from lesions in the optic tract or occipital cortex.
Example sentence: Homonymous hemianopia can lead to challenges in navigating the environment and recognizing objects on the affected side.
Luminance Contrast
The difference in brightness between an object and its background. It is crucial for detecting and distinguishing objects in the visual field.
Example sentence: Luminance contrast helps us perceive shapes and objects by highlighting differences in light intensity.
Magnocellular (M) Cell
Retinal ganglion cells that process motion and spatial information. These cells have large receptive fields and are sensitive to changes in light and movement.
Example sentence: Magnocellular cells play a vital role in detecting motion and guiding eye movements during visual tasks.
Ocular Dominance Column
Stripes of neurons in the visual cortex that respond preferentially to input from one eye. These columns are important for binocular vision and depth perception.
Example sentence: Ocular dominance columns help integrate visual input from both eyes to create a unified perception of the environment.
Opponent Process
A theory of color vision that proposes the existence of opposing color pairs: red-green, blue-yellow, and black-white. This mechanism helps explain color contrast and afterimages.
Example sentence: The opponent process theory accounts for our perception of color by emphasizing the relationships between complementary color pairs.
Optic Ataxia
Difficulty in using visual information to guide hand movements, often due to dorsal stream damage. Individuals with this condition struggle with tasks requiring accurate reaching and grasping.
Example sentence: Optic ataxia can impact activities like reaching for objects, pouring liquids, or grasping utensils during mealtime.
Optic Chiasm
The point where the optic nerves from each eye cross, allowing visual information to be processed by both hemispheres of the brain. This crossing is crucial for binocular vision.
Example sentence: The optic chiasm ensures that visual signals from the left and right visual fields are integrated in the brain for a unified perception.
Parvocellular (P) Cell
Retinal ganglion cells involved in processing fine visual details and color. These cells have small receptive fields and high spatial resolution.
Example sentence: Parvocellular cells contribute to our ability to detect fine patterns, textures, and colors in the visual environment.
Perception
The process of organizing, interpreting, and consciously experiencing sensory information. It allows individuals to understand and interact with their environment.
Example sentence: Perception shapes how we make sense of the world around us by integrating sensory input to create meaningful experiences.
Photoreceptor
Specialized cells in the retina (rods and cones) that convert light into neural signals. Photoreceptors initiate the process of visual perception by detecting light.
Example sentence: Photoreceptors play a crucial role in capturing light energy and converting it into electrical signals for visual processing.
Primary Visual Cortex (V1)
The region of the occipital lobe that receives and processes visual information from the retina. It is essential for basic visual functions such as edge detection and orientation.
Example sentence: The primary visual cortex is responsible for initial visual processing, including detecting edges, shapes, and motion in the environment.
Quadrantanopia
Loss of vision in one-quarter of the visual field, typically due to brain injury. This condition affects specific regions of the visual cortex or optic pathways.
Example sentence: Quadrantanopia can result in challenges recognizing objects or obstacles in the affected quadrant of the visual field.
Receptive Field
The specific area of the visual field to which a neuron responds. Neurons in the visual system have receptive fields that determine their response to visual stimuli.
Example sentence: The receptive field of a neuron defines the spatial location and features of stimuli that elicit a response from that neuron.
Retina
The light-sensitive layer at the back of the eye containing photoreceptors. The retina converts light into electrical signals that are sent to the brain for visual processing.
Example sentence: The retina acts as the initial sensory organ for vision, capturing light and transforming it into neural signals for processing in the brain.
