Sensory Systems and Visual Processing Flashcards

A comprehensive set of vocabulary flashcards covering sensory receptors, psychophysics, visual anatomy, the visual pathway, auditory processing, and chemical senses as well as vestibular senses based senses based on the lecture notes.

Enteroreceptors

Sensory receptors that respond to internal signals such as blood pressure, oxygen concentration, and pH levels to maintain homeostasis.

Exteroreceptors

Sensory receptors that collect signals from the external environment, including vision, hearing, touch, smell, and taste.

Primary Sensory Cells

Sensory cells possessing an axon that can generate action potentials, primarily found in olfactory organs.

Secondary Sensory Cells

Sensory cells that lack axons and transmit signals via synaptic transmission, common in taste and sound cells.

Signal Transduction

The process by which receptor cells capture energy from stimuli (e.g., light, sound) and convert it into electrical signals.

Receptor Potential

A graded electrical potential that varies in strength based on stimulus intensity and is localized to the area of stimulation.

Response Curve Phases

The three phases of the sigmoid curve representing the relationship between stimulus strength and cellular response: initial lag, working range, and saturation phase.

Weber's Law

A psychophysical principle that quantifies the just noticeable difference (JND) between stimuli, showing that the ability to perceive differences depends on the initial stimulus strength.

Weber-Fechner Law

The principle establishing that the relationship between stimulus strength and subjective experience follows a logarithmic pattern.

Stevens' Power Law

A theory suggesting that a power function described by the input/output relationship is better for describing sensory experience, especially at low intensity ranges.

Adaptation

The process by which sensory receptors adjust their sensitivity to prevent overstimulation, occurring at the filter, transducer, or enzyme levels.

Visible Spectrum

The range of wavelengths detectable by human vision, corresponding to $400-700\,\text{nm}$.

Accommodation

The ability of the eye lens to change shape for focusing on objects at varying distances, controlled by the ciliary muscle (Ziliarmuskel) and zonular fibers (Zonulafasern).

Altersweitsichtigkeit

Age-related farsightedness caused by decreased lens elasticity, resulting in the inability of the eyeball to round sufficiently for near vision.

Iris Sphincter Muscle

The muscle in the iris that contracts in response to light, causing pupil constriction via cholinergic parasympathetic innervation.

Retina

An extension of the central nervous system (CNS) derived from the diencephalon that contains photoreceptors and processing neurons.

Blind Spot

The area where the optic nerve exits the retina, which lacks photoreceptors.

Phototransduction

The process by which rods and cones convert light into neural signals.

Rhodopsin

The visual pigment in rods consisting of the protein opsin and $11\text{-cis retinal}$.

On-bipolar Cells

Bipolar cells in the cone pathway that depolarize in response to light.

Off-bipolar Cells

Bipolar cells in the cone pathway that hyperpolarize in response to light.

Alpha-cells (M-cells)

Large retinal ganglion cells with wide dendritic trees specialized for motion detection and coarse structures.

Beta-cells (P-cells)

Smaller retinal ganglion cells focused on fine detail analysis and color vision.

Trichromacy Theory

The theory proposed by Young and Helmholtz stating that three types of cones (red, green, blue) with different opsin proteins enable color vision.

Color Opponency Theory

The theory proposed by Ewald Hering stating that colors are processed in antagonistic pairs: red-green, blue-yellow, and black-white.

Lateral Geniculate Nucleus (LGN)

The thalamic nucleus that receives approximately $90\%$ of retinal ganglion cell axons and maintains a topographical map of the retina.

Parvocellular layers

The top four layers of the LGN consisting of small neurons that process fine detail and color.

Magnocellular layers

The bottom two layers of the LGN consisting of large neurons that process motion and coarse features.

Simple Cells

Neurons found in V1 layers 4 and 6 that are sensitive to orientation, position, and contrast with distinct excitatory and inhibitory areas.

Complex Cells

Neurons found in V1 layers 2, 3, and 5 that are sensitive to orientation but invariant to contrast reversal and lack distinct excitatory/inhibitory areas.

Ocular Dominance Columns

Columns in V1 that reflect input from both eyes, enhancing depth perception and stereopsis.

Ventral Stream

The 'what pathway' that travels from V1 to the temporal lobe for object identification and recognition.

Dorsal Stream

The 'where/how pathway' that travels from V1 to the parietal lobe for spatial awareness and motor coordination.

Prosopagnosia

A condition caused by lesions in the temporal cortex involving the inability to recognize faces.

Organ of Corti

The structure in the cochlea of the inner ear containing hair cells that convert sound waves into electrical signals.

Medial Superior Oliva (MSO)

A structure in the brainstem that detects timing differences to localize low-frequency sounds using a delay line system.

Lateral Superior Oliva (LSO)

A structure in the brainstem that detects volume differences to localize high-frequency sounds.

Inferior Colliculus (IC)

A relay center in the auditory pathway with tonotopic organization arranged in an 'onion-bulb' pattern of frequency-specific layers.

Vestibular Organ

A sensory system consisting of three semicircular canals and two macula organs responsible for sensing equilibrium and gravity.

Cupula

A gelatinous mass in the ampulla of the semicircular canals that bends with head movement to stimulate sensory hair cells.

Olfactory Sensory Neurons

G-protein coupled receptors in the nasal cavity that detect primary odorant classes and regenerate every two weeks.

Gustatory Qualities

The five basic taste qualities detected by secondary sensory cells in taste buds: sweet, salty, umami, sour, and bitter.