Sensory Systems Review PART II

What are primary receiving areas?

Areas of the cerebral cortex that are first to receive most of the signals initiated by a sense’s receptors.

What does the diencephalon make up?

The thalamus & hypothalamus.

How is the cerebrum (cortex) organized?

Right hemisphere (precentral sulcus, central sulcus, postcentral sulcus, and interparietal sulcus) and left hemisphere; with 4 lobes

What does unipolar, bipolar, and multipolar mean?

Unipolar: one axon, multiple dendrites

Bipolar: one axon, one dendrite

Unipolar: axon, no true dendrites

How is neuronal activity generated?

1. Electro-chemical forces: ions cross membrane

2. Equilibrium potential

3. Resting potential

4. Action potential

5. Propagation & myelination of axons

What are the basic tastes?

Salty, sour, sweet, bitter, and umami

What are the different types of taste cells?

Circumvallate papillae (back), foliate papillae (sides), and fungiform papillae (front)

What is the transmission to cortex that occurs for gustation?

Tongue → medulla oblongata → thalamus → gustatory cortex → orbitofrontal cortex

What is a taste pore?

An opening in a taste bud through which the tips of taste cells protrude

What are the requirements for odorants?

Small, volatile, and hydrophobic

What is a chemotopic map?

A pattern of activation in the olfactory system where chemicals with different properties create a map of activation based on these properties

What does the olfactory epithelium contain?

Cells & cilia that contain receptors for different odorants

How are different odorants recognized?

Shape theory: specific structure required to fit into the receptor

Molecule vibration theory: receptors sensitive to different vibration that molecules are making

What is the transmission to the cortex that occurs for olfaction?

Olfactory epithelium → olfactory bulb → olfactory tubercle, piriform cortex, amygdala; entorhinal cortex → thalamus, orbitofrontal cortex, hippocampus; or thalamus → orbitofrontal cortex

What is odortopy?

The olfactory bulb seems to show a spatial organization principle

What is the amygdala?

A subcortical structure involvd in emotional responding & processing olfactory signals

What is the olfactory bulb?

Receives signals directly from olfactory receptors; glomeruli receive signals from olfactory receptor neurons; mitral cells receive signals from olfactory receptor neurons & relays them to the brain

What is the retronasal route?

Opening from oral cavity → nasal pharynx → nasal cavity

What is oral capture?

Condition where sensation from olfaction & taste are perceived as being located in the mouth

What is population coding?

Principle of sensory processing where different values of perceptual attribute are coded by different patterns of activity in a whole neuron population

What are the three layers of the skin?

Epidermis, dermis, and hypodermis

What does the dermis contain?

Receptors that respond to stimulation

What are mechanoreceptors?

They respond to touch: free nerve endings, Merkel’s disc, Pacinian corpuscle, Meissner’s corpuscle, hair follicle receptors, Ruffini’s ending

What are thermoceptors?

They respond to temperature: warm receptors & cold receptors

What are nociceptors?

They respond to pain: mechanical, thermal, and polymodal

What is a rapidly adapting receptor?

Mechanoreceptors that respond with bursts of firing at the onset & offset of a pressure stimulus

What are slowly adapting receptors?

Mechanoreceptors located in epidermis & dermis that respond with prolonged activity to continued pressure

What is Troxler’s fading?

An unchanging stimulus will fade away

What is proprioception?

Perception of the position of limbs in space

What is kinesthesis?

Perception of body movements

What is haptic perception?

Combination of touch perception of patterns on skin surfaces & proprioception of hand movements

What is active touch?

Touch where observer plays active role in touching & exploring an object

What is cortical magnification?

Exaggerated cortical representation of one part of a sensory dimension or surface compared to another

What are cutaneous senses?

Ability to perceive sensation based on stimulation of skin receptors

What is rate code?

Principle where firing rate of a neuron carries information about the stimulus, associated with neural coding of magnitude

What is the spinothalamic pathway?

Carries information about skin temperature & pain: skin → spinal cord → thalamus → somatosensory cortex

What is the dorsal column-medial lemniscal pathway?

Carries signals from skin, muscles, & joints: skin/muscles → medulla oblongata → thalamus → somatosensory cortex

What is force?

Causes an object with mass to change its velocity

What is pressure?

Ratio of force to the area over which that force is distributed

What are sound waves?

Mechanical waves of pressure changes through some medium

What is amplitude perceived as?

Loudness

What is the sound pressure level?

Used to describe differences in pressure changes more comfortably

What is frequency?

Perceived as pitch

What is a pure tone?

Tone with pressure changes that can be described by a single sine wave

What is a complex tone?

Tone that consists of 2+ pure tones

What is additive synthesis?

Add pure tones to create complex tones

What is Fourier analysis?

Break complex waveforms into its pure tone components

What is timbre?

The perceived quality that distinguishes between 2 tones that sound different even though they have same loudness, pitch, & duration

What is the pinna?

What you see from outside, collects sound from a large area

What is the ear canal/auditory canal?

Allows sound to pass through skull, air vibrations travel to tympanic membrane

What is the tympanic membrane?

Where sound is collected & transmitted to ossicles - malleus, incus, and stapes

What is the malleus?

The first ossicle, receives vibrations from eardrum & transmits it to incus

What is the incus?

Second ossicle, transmits vibrations from malleus to stapes

What is the stapes?

Last ossicle, receives vibrations from incus & transmits to oval window

What is the acoustic reflex?

Muscles in ear tense when the SPL is very high to protect against painful sounds

What are the middle ear muscles?

Smallest skeletal muscles, attached to ossicles, contract in response to intense sounds & dampen vibrations of ossicles

What is the inner ear?

Contains the cochlea & receptors for hearing, filled with watery liquid; vestibular canal, round window, tympanic canal

What is the oval window?

Membrane covered hole in cochlea that receives vibrations from the stapes

What is the acoustic prism?

The way the cochlea separates frequencies entering the ear to create activity at different places along the basilar membrane

What is the cochlea?

Snail shaped structure that contains basilar membrane, tectorial membrane, and hair cells

What is the basilar membrane?

Stretches the length of the cochlea and controls vibration of cochlear partition

What is the Organ of Corti?

Body’s microphone, contains basilar membrane, tectorial membrane, & hearing receptors

What is a hair cell?

Contains cilia that are displaced by vibration of basilar membrane & fluids inside inner ear

What is the tectorial membrane?

Stretches length of cochlea, vibrations cause it to bend hair cells

How is sound information transmitted to the cortex?

Cochlea → medulla oblongata → pons → midbrain → thalamus → auditory cortex

What is the vestibular system?

Mechanism in the inner ear responsible for balance & sensing body position

What is electromagnetic radiation?

Form of radiant energy, propagates via electromagnetic waves or photons

What is illuminance?

Light that shines down onto us

What is luminance?

When light is reflected back off an object

What is reflectance?

Light on an object

What is the sclera?

White outer shell of the eye, doesn’t let light pass through

What is the iris?

Different colors, changes size & doesn’t let light pass through

What is the pupil?

Where light enters

What is the process of light transmission?

Cornea → iris/pupil → lens → retina

What is myopia?

Lens of eye too strong for length of eyeball, corrected with concave lens

What is hyperopia?

Lens of eye too weak for length of eyeball, corrected with convex lens

What are rods?

Low light levels, not in fovea, high sensitivity to light, slow recovery in the dark, no color vision

What are cones?

Day-time light levels, highest density in fovea, low sensitivity to light, quick recovery in the dark, color vision

What is the response of a photoreceptor in the dark?

Retinal present → triggers cGMP → Na+ & K+ channels active → Ca2+ release of neurotransmitters

What is the response of a photoreceptor to light?

Retinal released → cGMP disappears → Na+ channels close → K+ channels open → Ca2+ channels closing

What are the layers of the retina?

Photoreceptors → bipolar cells → ganglion cells → axons of optic nerve

What is the choroid?

Located behind the photoreceptors to make sure light isn’t reflected back into the eyes

What are horizontal cells?

Make lateral connections with receptors next to each other

What are amacrine cells?

Make lateral connections at the ganglion cell level

What are the 2 components of the ganglion cell receptive field?

An excitatory center & an inhibitory surround

What are the types of ganglion cells?

P-type (small, see detail, not good in temporal resolutions) & M-type (good temporal resolution, poor spatially, good for movement detection)

What is the superior colliculus?

Controls eye movements

What is the lateral geniculate nucleus?

In thalamus, sends neuron to primary visual cortex

What is the the transmission to cortex for vision?

Photoreceptor → bipolar cell → ganglion cell → superior colliculus

Photoreceptor → bipolar cell → ganglion cell → thalamus → visual cortex

What did Young & von Helmholtz propose in the trichromatic theory?

That color perception is based on 3 primary colors corresponding to 3 receptor types in the retina

What is trichromacy?

Normal color vision

What are the types of dichromacy?

Tritanopic: abnormal S-opsin

Deuteranopic: abnormal M-opsin

Protanopic: abnormal L-opsin

What did Hering propose in the opponent processing theory?

Color perception is based on by the activity of three opponent systems (white vs black, blue vs yellow, red vs green)

What is synesthesia?

Phenomenon where there’s an inducer & then a concurrent response, an associated subjective experience paired with a completely different sensory modality or quality

What is multisensory integration?

Combined use of multisensory signals is often beneficial, brain combines information from 2 modalities to improve reaction times

At which wavelength is each type of color absorbed?

Blue: 420 nm

Green: 535 nm

Red: 565 nm