L7: Neural Circuits for Visual Perception: Receptive Fields

L7

ON-centre Ganglion Cell

Ganglion cell that responds to light in centre.

Lateral Inhibition

inhibition of ganglion cells by neurons that receive input from neighbouring activated receptors in the inhibitory regions of the receptive field, and in this case in the surrounding area of its receptive fields

Photoreceptors

Cells in the retina that detect light and colour and send signals initiating vision

Intermediate Neurons

Neurons that process signals between photoreceptors and ganglion cells.

Amacrine Cells

Type of intermediate neuron in the retina.

Horizontal Cells

Neurons that connect photoreceptors to ganglion cells.

Convergence

Multiple photoreceptors connecting to a single ganglion cell.

Hartline's Discovery

Identified receptive fields in frog's retina.

Receptive Field Overlap

Multiple ganglion cells respond to the same retinal area.

Kuffler's Research

Studied centre-surround receptive fields in mammalian ganglion cells.

Inhibition

Decrease in firing rate of a neuron due to overstimulation.

Centre-Surround Receptive Field

Cell type with distinct responses to excitatory centre and inhibitory surround.

These enhance edge detection.

Light Stimulation

Shining light on the retina to elicit responses.

Specific Area Response

Ganglion cells fire when light hits specific retinal areas.

Sensory Pathway

Neural pathway transmitting sensory information to the brain.

Visual Perception

Interpretation of visual stimuli by the brain.

Cognition

Mental processes involved in perception and understanding.

Centre-Surround Neuron Fields

Neurons with excitatory center and inhibitory surround.

On-Centre Cells

Neuron excited by center stimulation (light), inhibited by surround.

Off-Centre Cells

Neurons inhibited by light in center (centre stimulation), excited by surround.

Maximally stimulated by surround, not centre.

Hubel and Wiesel

Researchers studying visual systems using cats.

Study on visual processing in LGN cells.

Stimuli Presentation

Visual stimuli presented on screen to test neurons.

Sedated Animals

Cats were sedated to prevent eye movement.

Retina Response

Specific retina areas respond to stimulated screen regions.

Physiological Approach

Method focusing on neuron activity and responses.

Electrode Measurement

Electrodes measure neuron firing rates and action potentials.

Reference Electrode

Placed away to measure electrical potential differences.

Amplifier Signals

Signals amplified for computer recording and analysis.

Neuronal Firing Sound

Clicks indicate neuron firing intensity during experiments.

Stimulus Area Response

Neurons respond based on specific screen stimulus areas.

Firing Rate

Frequency of action potentials in a neuron.

Inhibitory Area

Stimulus in this area reduces neuron firing rate.

Spontaneous Activity

Baseline firing when stimulus outside receptive field.

Maximal Response

Greatest firing when entire center is stimulated.

Photoreceptor Stimulation

More receptors stimulated equals stronger neuron response.

Ganglion Cells

Retinal cells transmitting visual information from the retina to the brain.

Smaller Dot Response

Smaller stimuli produce weaker responses in on-centre cells.

Larger Dot Response

Larger stimuli covering entire center elicit stronger responses.

Receptive Field

Area where stimulus affects neuron firing rate.

Centre-Surround Antagonism

Interaction where centre and surround regions affect firing.

Excitatory and inhibitory inputs cancel each other out.

Bipolar Cells

Intermediate cells pooling inputs from photoreceptors.

Intermediate Neurons

Send inhibitory signals to ganglion cells.

Excitatory Input

Stimulus that increases neuron firing rate.

Visual Information Encoding

Process of converting visual stimuli into neural signals.

Amacrine Cells

Cells providing lateral inhibition in the retina.

Horizontal Cells

Cells that connect photoreceptors and bipolar cells.

Optic Nerve

Bundle of ganglion cell axons forming the visual pathway transmitting visual info from retina to brain.

Stimulus Size

Dimension of an object affecting visual perception.

Location Encoding

Determining where stimuli are in visual space.

Feature Extraction

Process of identifying specific characteristics in vision.

Luminance Contrast

Difference in brightness between objects.

Edge Detection

Identifying boundaries between different visual elements.

Photoreceptor Types

Rods and cones that detect light differently.

Neural Circuit

Network of neurons interacting to process information.

Hermann Grid

Optical illusion affecting color perception at intersections.

Luminance Contrast

Difference in light intensity affecting visual perception.

Contrast Illusion

Perception altered by surrounding visual context.

Visual Edges

Boundaries perceived due to contrast differences.

Perceptual Darkening

Illusion of darker areas at intersections.

Background Luminance

Light intensity of surrounding area affecting perception.

Visual Stimuli

Objects or patterns that are visually perceived.

Perception of Color

Interpretation of wavelengths as colors by the brain.

Antagonism

Opposing responses in visual processing.

Excitation vs. Inhibition

Balance of signals determining neuron activity.

Visual Illusion

Misinterpretation of visual information by the brain.

Perceptual Differences

Variations in perception based on context.

Edge detection

Identifying boundaries between different visual stimuli.

Inhibitory surround

Region surrounding centre that suppresses neuron activity.

Excitatory center

Region of receptive field that increases cell firing.

Response pattern

Firing rate variation based on stimulus position.

Chevreul Illusion

Visual phenomenon enhancing perceived brightness at edges.

Luminance

Intensity of light emitted or reflected from surfaces.

Colour opponency

Processing of color differences in visual perception.

Interaction of different cone wavelengths in vision.

Red-green channel

Compares long and medium wavelengths of light.

Stimulus intensity

Strength of visual input affecting cell response.

Visual field

Area of vision perceived by the eyes.

Inhibitory input

Stimulus that decreases neuronal activity.

Edge placement

Location of an edge affecting ganglion cell response.

Response differentiation

Variation in response based on stimulus location.

Visual pathway

Pathway through which visual information is processed.

Intensity of stimuli

Strength of light affecting ganglion cell firing.

Perception of brightness

How light intensity is interpreted visually.

Distance enhancement

Perception of increased separation between visual edges.

Red-Green Opponent Cells

Excited by red, inhibited by green wavelengths.

Blue-Yellow Opponent Cells

Excited by blue, inhibited by long/medium wavelengths.

Centre-Surround Organization

Spatial arrangement of excitatory and inhibitory responses.

Retinal cells respond differently to center and surround.

Luminance Differences

Variations in light intensity perceived by the retina.

Edge Detection

Ability to identify boundaries between different colors.

Colour Encoding

Processing of color differences by ganglion cells.

Orientation Encoding

Ganglion cells cannot determine stimulus orientation.

Thalamus

Brain structure relaying sensory information to cortex.

Retinotopic Mapping

Spatial arrangement of visual information in LGN.

Excitatory Centre

Region of receptive field that activates neuron.

Neural Transmission

Process of sending signals through neurons.

Cerebral Cortex

Outer layer of the brain involved in processing.

Occipital Lobe

Brain region housing the primary visual cortex.

Sensory Relay System

Thalamus acts as a hub for sensory information.

Retina

Light-sensitive layer at the back of the eye.

Retinotopic Map

Spatial arrangement of visual input in LGN.

On-Off Center Surround

Receptive field organization in LGN neurons.