Cortical Organization and Perception Study Guide

Flashcards covering key vocabulary and concepts from a study guide on cortical organization and perception.

V1 Organization

Organized as a retinotopic map.

Cortical Magnification

An area of the fovea is magnified onto V1, resulting in more representation.

Imaging Techniques for Cortical Organization

fMRI measures hemoglobin in blood, while PET uses radioactive tracers to measure blood flow.

Types of Cortical Cells

Simple and complex cortical cells organized into columns.

Location Columns

Respond based on the location of receptive fields on the retina.

Orientation Columns

Columns that fire to the orientation of stimuli, such as degrees.

Visual Acuity and Fovea

Visual acuity decreases as you move away from the fovea.

Visual Crowding

Clutter in the periphery makes it harder to perceive details.

Hypercolumns

Location columns containing multiple orientation columns; each receives information for all possible orientations.

Dorsal Pathway

The pathway in the brain responsible for object location, connecting V1 to the parietal lobe.

Modularity in the Brain

Specific brain structures respond to specific stimuli, like the what/where streams.

Prosopagnosia

Inability to recognize faces due to damage in the fusiform face area.

Face-Inversion Effect

Difficulty in recognizing faces when they are upside down, demonstrating a holistic processing approach.

Color Mixing Types

Subtractive color mixing is about paint, while additive color mixing involves light.

Opponent Process Theory

All colors can be represented by four primary chromatic colors in two opposing pairs.

Illusory Contours

Visual illusions where people interpret shapes that are not actually present.

Good Continuation Principle

Connected points resulting in smooth, straight curves are perceived as belonging together.

Cerebral Achromatopsia

Difficulty experiencing color due to damage in the cortex.

Chromatic Adaptation

Prolonged exposure to certain colors leads to changes in receptor sensitivity.

Optic Flow

The appearance of objects as an observer moves through the environment.

Tau

Utilizes the rate of expansion of an object on the retina to estimate time to collision.

Corollary Discharge Theory

Accounts for eye movement when perceiving motion, involving three signals: IDS, MS, CDS.

How is V1 organized?

Organized as a retinotopic map.

What is cortical magnification?

An area of the fovea is magnified onto V1, resulting in more representation.

What imaging technique measures hemoglobin in blood?

fMRI measures hemoglobin in blood, indicative of brain activity.

What imaging technique measures blood flow using radioactive tracers?

PET uses radioactive tracers injected into the bloodstream to measure blood flow.

What are the two types of cortical cells?

Simple and complex cortical cells organized into columns.

What are location columns?

Columns that respond to specific locations of receptive fields on the retina.

What are orientation columns?

Columns that fire in response to the orientation of stimuli.

What happens to visual acuity as you move away from the fovea?

Visual acuity decreases as you move away from the fovea.

What is visual crowding?

Perceptual difficulty due to clutter in the periphery.

What are hypercolumns?

Location columns with multiple orientation columns, receiving information for all possible orientations.

What is the Dorsal pathway?

The pathway in the brain responsible for object location, connecting V1 to the parietal lobe.

What is the Ventral pathway?

The pathway responsible for object identity, connecting V1 to the temporal lobe.

Define modularity in the brain.

Specific brain structures respond to specific stimuli, such as the what/where streams.

What happens with damage to the what pathway?

Agnosia occurs, leading to an inability to recognize visual objects.

What is prosopagnosia?

Inability to recognize faces due to damage in the fusiform face area.

What is the face-inversion effect?

Difficulty in recognizing faces when they are upside down, revealing a holistic processing approach.

What is the parahippocampal place area (PPA)?

A region that responds to spatial layout and spatial scenes.

What is the extrastriate body area (EBA)?

A region that responds to images of full body parts.

What is sensory coding?

The representation of perceived objects through neural firing.

What is the principle of univariance?

Once a photon is absorbed by a pigment, the identity of its wavelength is lost.

What is color constancy?

Constant perception of colors even when illumination changes.

What is chromatic adaptation?

Prolonged exposure to certain colors leads to changes in receptor sensitivity.

Define optic flow.

The appearance of objects as an observer moves through the environment.

What is tau in relation to motion perception?

A ratio utilizing the rate of expansion of an object on the retina to estimate time to collision.

What is spatial updating?

Keeping track of position within a surrounding environment while moving.

What are CO blobs?

Cytochrome oxidase blobs that help process columns in the visual cortex.

How do hypercolumns relate to binocular vision?

We form right and left ocular dominance columns; half hypercolumns are dedicated to the right eye and half to the left.

What is the role of columns in visual perception?

Columns undergo tiling to cover the entire visual field, with location columns targeting specific picture areas and orientation columns responding to their orientation.

What happens to visual acuity in cluttered environments?

Visual acuity is negatively influenced by peripheral clutter, making detail perception harder due to more neurons being engaged.

What are the two main pathways in the visual processing system?

The Dorsal pathway for object location and the Ventral pathway for object identity.

Define apparent movement.

The illusion of movement where no actual movement takes place, often seen in screens/images.

What is the purpose of sensory coding?

To represent perceived objects through patterns of neural firing, including specificity, population, and sparse coding.

What is the significance of viewpoint invariance?

The ability to recognize objects regardless of the perspective from which they are viewed.

Define good continuation in Gestalt principles.

The principle that connected points result in smooth and straight curves perceived as belonging together.

What is perceptual organization?

The brain's method of organizing elements into coherent groups based on grouping and segregating principles.

What characterizes chromatic colors?

Colors like red, blue, and green that reflect specific wavelengths more than others.

What defines achromatic colors?

Colors such as white, gray, and black that reflect all wavelengths equally.

What is the relationship between hue, saturation, and value?

Hue refers to the color type, saturation indicates the intensity of the color, and value denotes its brightness in a 3D color space model.

What are the main components of optic flow?

Gradient flow, which changes in speed based on distance from the observer, and focus expansion, where an area of no flow is identified as the endpoint.

What is the function of grid cells in navigation?

Grid cells represent large environments with multiple place fields and fire in a grid-like pattern as animals navigate.

What are some limitations of structuralism in perception?

Does not explain the illusion of movement; focuses on sensation versus perception but neglects how perception occurs during darkness or obscured objects.

What is illusory contours?

Visual illusion where shapes are perceived that are not actually present, e.g., interpreting a triangle formed by edges that are not actually there.

Define Gestalt Approach in perception.

A set of rules that describe how elements in a picture are grouped together or segregated into coherent units.

What are the principles of grouping in Gestalt psychology?

Good continuation, Pragnanz, similarity, proximity, common fate, common region, and uniform connectedness help explain how we perceive grouped elements as unified.

What is perceptual segregation?

The process of separating objects from each other, including distinguishing a figure from its background.

What defines color constancy?

The ability to perceive colors consistently under varying lighting conditions due to the brain's adjustments based on context and surrounding colors.

What is the role of double-opponent neurons in color perception?

They respond to specific color contrasts, enhancing color discrimination in visual processing by facilitating the perception of surrounding colors.

What is characteristic of chromatic adaptation?

Temporary change in color perception due to prolonged exposure to specific wavelengths, leading to decreased sensitivity to those colors.

What is the basic principle of opponent process theory?

Colors are organized into opposing pairs: red-green and yellow-blue, allowing the visual system to process different color stimuli efficiently.

What is meant by distributed representation in perception?

Activation of multiple brain regions during the perception of an object, showing that perception does not reside in a single area.