PerLecture 3 - Neurons and Perception Lecture Notes

A set of vocabulary flashcards covering neurons, retinal anatomy, receptive fields, lateral inhibition, and cortical visual processing based on the lecture notes.

Santiago Ramon y Cajal

A researcher who used silver chromate staining techniques to identify individual neurons and discovered the nervous system is made of billions of separate cells communicating at synapses.

Silver chromate

The staining technique used by Santiago Ramon y Cajal to look at individual neurons.

Retinal Neural Network vertical signals

The pathway where rods and cones send signals through bipolar cells and ganglion cells’ axons.

Retinal Neural Network horizontal signals

Signals sent within the retina by Horizontal cells and Amacrine cells.

Rod-to-ganglion convergence ratio

A high convergence ratio of $120:1$, which increases sensitivity to light but decreases detail resolution.

Cone-to-ganglion convergence ratio

A lower convergence ratio of $6:1$ (which may be $1:1$ in the fovea), leading to high visual acuity but requiring more light.

Visual Acuity

The ability to discriminate details, which is highest in the all-cone fovea region due to $1:1$ wiring.

Visual Receptive Field

The region on the retina where receiving light increases or decreases the firing rate of a neuron.

Excitatory-Centre, Inhibitory-Surround

A ganglion cell receptive field that is "on" when light hits the centre and "off" when light hits the surrounding area.

Inhibitory-Centre, Excitatory-Surround

A ganglion cell receptive field that is "off" when light hits the centre and "on" when light hits the surrounding area.

Center-Surround Antagonism

A process where output changes depending on the area stimulated, with highest response in the excitatory area and lowest in the inhibitory area.

Kuffler (1950)

The researcher who mapped out the characteristics of ganglion cells.

Lateral Inhibition

The capacity for one neuron to reduce the firing of its neighbor, occurring in many different sensory systems.

Limulus

The Horseshoe Crab used in experiments to demonstrate that adding light to neighboring receptors reduced the firing rate of an initial nerve fiber.

Lateral Plexus

A structure that shares information horizontally between cells, allowing brightly stimulated neurons to slow the firing rate of a neighbor.

Chevreul Effect

An illusion where neurons at bright/dark borders inhibit neighbors unevenly, exaggerating contrast at edges due to lateral inhibition by retinal ganglion cells.

Visual Processing Pathway

The information route consisting of the Optical nerve, Lateral geniculate nucleus (LGN), Striate cortex, and Extrastriate cortex.

Cortical magnification factor

The phenomenon where the fovea accounts for only $0.01\%$ of the retina but its information accounts for $8\text{-}10\%$ of the visual cortex in $V1$.

Feature Detectors

Neurons that fire to specific features of a stimulus, forming part of the early steps of visual processing.

Simple cortical cell

A $V1$ cell with well-defined excitatory ("on") and inhibitory ("off") fields that is selective for orientation and position.

Complex cortical cells

$V1$ cells that possess orientation sensitivity only and can be motion-selective.

End-stopped cortical cell

A $V1$ cell uniquely sensitive to light orientation and length, where stimuli that are too long become inhibitory.

Cortical cell to optic nerve ratio

The ratio of $1000$ cortical cells to $1$ optic nerve fibre (ganglion cell axon).

Rearing Studies

Research involving raising animals in specific environments, such as the Blakemore and Cooper (1970) study with cats, providing evidence for neural plasticity.

Transduction

The process of converting environmental stimuli into electro-chemical impulses in neurons.

Spatial Frequency

The number of luminance bands (dark to light) over a given distance, measured in cycles/degrees.

Binocular Rivalry

A phenomenon where the visual system perceives one of two incompatible images shown to each eye, alternating between them rather than seeing both at once.

Amplitude Spectra

A description of how much energy is present at each spatial frequency in an image.