LO5

receptor cells

Specialized cells in every sensory system of the body that can turn internal or external stimuli energy to electrical energy that the brain can process.

labeled lines

the concept that each nerve input to the brain reports only a particular type of information

sensory transduction

the process in which a receptor cell converts the energy in a stimulus into a change in the electrical potential across its membrane

touch receptor cells

located beneath the skin, respond to vibration, pressure, perceive forms of objects we touch, detect stetching when we move our finger or arms, detect pain, itch, heat and cold stimuli

Encoding of spatial information for somatosensation

refers to how the nervous system represents where a touch, pressure, pain, or other somatic stimulus occurs on the body. there are multiple sensory receptor cells that measure the each specific intensity that cover the entire range.

somatonsensory system

"body sensation" system

receptive field

the stimulus region and features that affect the activity of a cell in a sensory system

Sensory adaptation

the progressive loss of receptor response as stimulation is maintained. Phasic receptors drop actions potentials as a stimuli is maintained, and tonic receptors decline or show no action potentials at all to show duration of stimuli.

central modulation of sensory information

the process in which higher brain centers, such as the cortex and thalamus, suppress some sources of sensory information and amplify others

Sensory homunculus in primary somatosensory cortex

Demonstrates that the area of the cortex dedicated to the sensations of various body parts is proportional to how sensitive that part of the body is. exp hands and lips are big.

synesthesia

A condition in which stimulation of one sense also evokes another

Plasticity of sensory cortices

brain adapts to current surroundings and experiences, exp: an artist without arms has heightened sensory skills in their toes.

decibels

A unit of measurement of loudness

hertz

the unit of frequency, equal to one cycle per second

transduction

conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brains can interpret.

tympanic membrane

The eardrum. A structure that separates the outer ear from the middle ear and vibrates in response to sound waves.

ossicles

three tiny bones in the middle ear that vibrate when ear drum moves

middle ear

the chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window

oval window

membrane at the entrance to the cochlea through which the ossicles transmit vibrations

inner ear

the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

basilar membrane

A structure that runs the length of the cochlea in the inner ear and holds the auditory receptors, called hair cells.

inner hair cells

one of the receptor cells for hearing in the cochlea, named for the stereocilia that protrude from the top of the cell and transduce vibrational energy in the cochlea into neural activity.

tectorial membrane

A gelatinous membrane located atop the organ of Corti.

Stereocilia

hairlike extensions on the tips of hair cells in the cochlea that initiate the release of neurotransmitters when they are flexed

Mechanism of transduction

Fluid movement causes basilar membrane to vibrate. Hair cells in organ of Corti bend → open ion channels. Ion flow → electrical signal → neurotransmitters released (Glutamate). Signal travels via auditory nerve to the brain.

Inferior colliculi

paired gray matter structures of the dorsal midbrain that process auditory information

Medial geniculate nuclei (MGN, thalamus)

Either of two nuclei - left and right - in the thalamus that receive input from the inferior colliculi and send output to the auditory cortex

Tonotopic organization

the organization of auditory neurons according to an orderly map of stimulus frequency, from low to high

retina

the receptive surface inside the eye that contains photoreceptors and other neurons

lens

a structure in the eye that helps focus an image on the retina

photoreceptors

neural cells in the retina that respond to light

rods

a photoreceptor cell in the retina that is most active at low levels of light

cones

any of several classes of photoreceptor cells in the retina that are responsible for color vision

bipolar cells

an interneuron in the retina that receives information from rods and cones and passes the information to retinal ganglion cells

ganglion cells

any of a class of cells in the retina whose axons form the optic nerve

optic nerve

a collection of ganglion cell axons that extends from the retina to the brain, and carries info

Photopic system

operates at high levels of light, shows sensitivity to color, and involves the cones. Needs strong stimulation and works in daylight, concentration in or near fovea, rapid response time.

Scotopic system

a system in the retina that operates at low levels of light and involves the rods. Needs less stimulation, for night vision, located outside fovea, slow response time.

photoreceptor adaptation

the tendency of rods and cones to adjust their light sensitivity to match current levels of illumination

visual acuity

sharpness of vision

fovea

the central portion of the retina, which is packed with the highest density of photoreceptors and is the center of our gaze

Optic disc

the region of the retina that is devoid of receptor cells because ganglion cell axons and blood vessels exit the eyeball there

Blindspot

the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there. Our brain makes up what we think should be there which is wy we don't "see" the blind spot.

Occipital cortex

Also called visual cortex. The cortex of the occipital lobe of the brain.

Optic chiasm

the point at which parts of the two optic nerves cross the midline

Lateral geniculate nucleus (LGN)

the part of the thalamus that receives information from the optic tract and sends it to visual areas in the occipital cortex

Visual pathways in human brain

Light hits retina → activates photoreceptors (rods/cones). Signal travels to bipolar cells, then to ganglion cells. Optic nerve carries signal from each eye. At optic chiasm → info from nasal side of each retina crosses sides. Signals continue via optic tracts to the thalamus (lateral geniculate nucleus, LGN). From LGN → sent to primary visual cortex (V1) in occipital lobe. Visual info processed in dorsal (where) and ventral (what) streams.

Visual field

the whole area that you can see without moving your head or eyes

Topographic projection (aka retinotopic mapping)

a mapping that preserves the point-to-point correspondence between neighboring parts space. for example, a topographic projection extends from the retina to the cortex

blindsight

the paradoxical phenomenon whereby, within a scotoma, a person cannot consciously perceive visual cues but may still be able to make some visual discrimination