Sensation and Perception Comprehensive Flashcards

Vocabulary flashcards covering core topics in Sensation & Perception including neuroanatomy, signal detection theory, eye optics, retinal organization, spatial vision, and visual pathways.

Sensation

The registration of environmental stimuli by sensory organs such as the eyes and ears.

Perception

The organization and interpretation of signals sent to the brain by sensory organs.

Adaptation

A reduction in neural or sensory response caused by prior or continuing stimulation.

Sensory Transduction

The process of converting physical energy (such as light or sound) into neural energy by sensory receptors.

Dualism

The philosophical position that the mind and brain are separable entities.

Materialism

The philosophical position that perception is a direct product of the nervous system and that both brain and mind are composed of physical matter.

Empiricism

The perspective that sensory experience is the only source of knowledge about the world.

Bottom-Up Processing

Perceptual processing that begins with the physical stimulus at the sensory organ and moves toward higher-level neural processing.

Top-Down Processing

Perceptual processing originating in the brain that uses memory, expectations, attention, and motivation to influence perception.

Doctrine of Specific Nerve Energies

Müller's doctrine stating that the nature of a sensation depends on which sensory nerve fibers are stimulated, rather than how they are stimulated.

Psychophysics

The scientific study of the mathematical and functional relationships between physical stimulus properties and conscious perceptual experience.

Absolute Threshold

The minimum intensity of a stimulus needed for an organism to detect its presence $50\times 10^{-2}$ (or $50\text{\%}$) of the time.

Method of Limits

A psychophysical method where stimulus intensity is gradually increased or decreased in steps until the subject's detection response changes, averaging multiple crossover points.

Method of Constant Stimuli

A psychophysical method in which stimuli of varying predetermined intensities are presented in random order to establish a threshold curve.

Method of Adjustment

A psychophysical method in which the observer directly adjusts the stimulus intensity until it is just detectable.

Signal Detection Theory (SDT)

A framework quantifying perceptual decisions under uncertainty, separating an observer's physical sensitivity from non-sensory response bias.

Criterion ($\beta$)

In Signal Detection Theory, the internal threshold level of sensory activity above which an observer decides a signal is present.

Sensitivity ($d'$)

A quantitative measure of an observer's ability to detect a signal relative to noise, represented by the separation between noise and signal-plus-noise distributions.

Receiver Operating Characteristic (ROC) Curve

A graphic plotting hit rate against false alarm rate across different response criteria, illustrating sensitivity ($d'$).

Stevens' Power Law

A psychophysical principle stating that psychological sensation magnitude is proportional to physical stimulus magnitude raised to an exponent.

Anatomical Directional Terminology

Descriptive axes used in neuroanatomy: Medial (middle), Lateral (side), Anterior/Rostral (front), Posterior/Caudal (back/tail), Dorsal/Superior (above), and Ventral/Inferior (below/belly).

Afferent Nerve

A sensory nerve that carries signals from peripheral receptors inward to the central nervous system.

Efferent Nerve

A motor nerve that carries signals outward from the central nervous system to muscles or glands.

Gyri and Sulci

Gyri are the raised folds or ridges on the cerebral cortex; sulci are the shallow grooves or depressions separating them.

Frontal Lobe

Cortical lobe responsible for executive control, planning, inhibition, motor execution, language production, emotion, and personality.

Parietal Lobe

Cortical lobe involved in processing somatosensory information, spatial representation, and spatial attention.

Temporal Lobe

Cortical lobe responsible for auditory processing, complex visual object recognition, memory formation, and language comprehension.

Occipital Lobe

The posterior cortical lobe dedicated entirely to processing visual information.

Action Potential

An all-or-none electrical impulse that travels down a neuron's axon when the membrane potential reaches a threshold of approximately $-50\text{\,}mV$.

Rate Coding

A neural coding scheme where stimulus intensity is represented by the frequency or rate of action potentials fired per unit time.

Five Stages of Neurotransmission

The sequential steps of chemical signaling: 1. Synthesis, 2. Storage, 3. Release (exocytosis), 4. Receptor Action, and 5. Inactivation (reuptake or degradation).

Neural Convergence

The wiring pattern in which multiple presynaptic neurons synapse onto and send signals to a single postsynaptic neuron.

Contralateral Organization

The arrangement in which one side of the brain controls and receives sensory input from the opposite side of the body or visual field.

Cornea

The transparent front surface of the eye that refracts light and accounts for approximately two-thirds of the eye's total optical power.

Iris

The pigmented muscular ring that regulates the amount of light entering the eye by controlling the size of the pupil.

Eye Anatomy Overview

Key visual structures of the eye including the cornea, anterior chamber, pupil, iris, ciliary muscle, crystalline lens, vitreous chamber, sclera, choroid, retina, fovea, optic disc, and optic nerve.

Accommodation

The process by which the crystalline lens changes shape via ciliary muscle contraction to alter optical power and bring objects at varying distances into focus.

Emmetropia

The refractive condition of an eye with no optical error, where light focuses perfectly onto the retina.

Myopia

Nearsightedness; a refractive condition where light entering the eye focuses in front of the retina, requiring a concave lens for correction.

Hyperopia

Farsightedness; a refractive condition where light entering the eye focuses behind the retina, requiring a convex lens for correction.

Rods

Photoreceptors specialized for night vision (scotopic system) that have high light sensitivity, low spatial acuity, and show no color selectivity.

Cones

Photoreceptors specialized for daylight vision (photopic system) that provide high visual acuity and color vision.

Fovea

A small central pit in the retina containing a high density of cones and no rods, responsible for maximum visual acuity.

Optic Disc

The site on the retina where ganglion cell axons exit to form the optic nerve; contains no photoreceptors, creating a blind spot.

Phototransduction

The biochemical process in photoreceptors where absorbed light causes photopigment isomerization, reducing glutamate release.

Inverting Bipolar Cells

Bipolar cells that respond to light-induced decreases in glutamate by increasing their firing rate (ON response).

Non-Inverting Bipolar Cells

Bipolar cells that respond to light-induced decreases in glutamate by decreasing their firing rate (OFF response).

Midget Bipolar Cells

Bipolar cells located in the central retina that receive input from a single cone and project to single ganglion cells, preserving high visual acuity.

Diffuse Bipolar Cells

Bipolar cells in the peripheral retina that receive convergent input from multiple photoreceptors, increasing sensitivity at the expense of acuity.

ON-Center Ganglion Cell

A retinal ganglion cell that increases its firing rate when light hits the center of its receptive field and decreases firing when light hits the surround.

OFF-Center Ganglion Cell

A retinal ganglion cell that decreases its firing rate when light hits the center of its receptive field and increases firing when light hits the surround.

Lateral Inhibition

Antagonistic neural interaction mediated by horizontal and amacrine cells across neighboring retinal pathways that sharpens edge perception.

Retinitis Pigmentosa

A hereditary degenerative disease characterized by initial destruction of rods and loss of peripheral visual field.

Age-Related Macular Degeneration

A disease affecting the central retina (macula) that destroys high-acuity foveal vision while sparing peripheral vision.

Visual Angle

The angle subtended by an object at the lens of the eye, indicating the physical size of the image projected onto the retina.

Spatial Frequency

The number of light and dark bar cycles in a visual grating per degree of visual angle.

Nyquist Frequency

The minimum sampling rate required to accurately resolve a spatial pattern, equal to twice the spatial frequency ($2F$).

Aliasing

Perceptual distortion that occurs when a visual scene is sampled below the Nyquist frequency, causing high spatial frequencies to appear as low spatial frequencies or solid gray.

Multi-Channel Model of Spatial Vision

The theory that the visual system processes visual information through multiple parallel channels, each tuned to a specific range of spatial frequencies.

Contrast Sensitivity Function (CSF)

A curve plotting visual sensitivity as a function of spatial frequency, showing peak sensitivity around $7\text{\,cycles/degree}$ in human photopic vision.

Selective Adaptation

A experimental technique in which prolonged exposure to a specific spatial frequency or orientation selectively fatigues responsive neurons, temporarily reducing sensitivity to that specific feature.

Population Coding

A neural representation scheme in which a stimulus parameter is encoded by the pattern of activity across an entire population of tuned neurons.

Interocular Transfer

The transfer of a perceptual adaptation effect from one adapted eye to the unadapted eye, demonstrating that the adaptation occurs in binocular cortical neurons (V1).

Geniculostriate Pathway

The primary conscious visual pathway: Eye $\rightarrow$ Optic Nerve $\rightarrow$ Optic Chiasm $\rightarrow$ Optic Tract $\rightarrow$ Lateral Geniculate Nucleus (LGN) $\rightarrow$ Optic Radiations $\rightarrow$ Primary Visual Cortex (V1).

Retinotopic Map

The orderly spatial mapping of the retina preserved across visual structures, where adjacent positions on the retina are represented by adjacent neurons in the brain.

Tectopulvinar Pathway

A visual pathway projecting to the superior colliculus in the midbrain that mediates unconscious visual orienting and eye movements.