psych soc section

R etinal disparity

Retinal disparity (eyes are 2.5 inches apart)

Convergence

Convergence – things far away, eyes are relaxed. Things close to us, eyes contract.

relative size

relative size, interposition (overlap), relative height (things higher are farther away), shading and contour, motion parallax (things farther away move slower)

i nner ear muscle

Hearing - inner ear muscle: higher noise = contract.

just noticeable difference (JND)

The threshold at which you’re able to notice a change in any sensation is the just noticeable difference (JND)

Delta I/I = k

Delta I/I = k (Weber’s Law)

linear relationship

If we take Weber’s Law and rearrange it, we can see that it predicts a linear relationship bet

50%

The minimum intensity of stimulus needed to detect a particular stimulus 50% of the time

difference threshold (JND)

Not the same as the difference threshold (JND) – that’s the smallest difference that can be detected 50% of the time.

Subliminal

Subliminal stimuli – stimuli below the absolute threshold.

inner ear

Focus on inner ear - in particular the semicircular canals (posterior, lateral, and anterior)

endolymph

Canal is filled with endolymph, and causes it to shift – allows us to detect what direction our head is moving in, and the strength of rotation.

Otolithic organs

Otolithic organs (utricle and saccule) help us to detect linear acceleration and head positioning. In these are Ca crystals attached to hair cells in viscous gel. If we go from lying down to standing up, they move, and pull on hair cells which triggers AP.

Bottom up

Bottom up: stimulus influences our perception.

Top-down

Top-down: background knowledge influences perception. Ex. Where’s waldo

Conjunctiva

Conjunctiva is first layer light hits

Cornea

Cornea – transparent thick sheet of tissue, anterior 1/6th.

Anterior chamber

Anterior chamber – space filled with aqueous humour, which provides pressure to maintain shape of eyeball.

Pupil

Pupil is hole made by iris, which determines eye color

Lens

Lens bends the light so it goes to back of eyeball.

Suspensory ligaments

Suspensory ligaments, attached to a ciliary muscle. These two things together form the ciliary body, what secrets the aqueous humor.

Posterior chamber Is

Posterior chamber Is area behind the ciliary muscle, also filled with aqueous humor.

Vitreous chamber

Vitreous chamber – filled with vitreous humour, jelly-like substance to provide pressure to eyeball.

Retina

Retina is filled with photoreceptors.

Choroid

Choroid – pigmented black in humans, a network of blood vessels. Bc black all light is reflected.

Sclera

Sclera – whites of the eye, thick fibrous tissue that covers posterior 5/6th of eyeball. Attachment point for muscles.

light

Sensation requires light -> neural impulse, by a photoreceptor

rods

Light enters pupil and goes to retina, which contains rods and cones

rods,

There are 120 million rods, for night vision

cones

There are 6-7 million cones

fovea

Almost all cones are centered in fovea

Phototransduction Cascad

Phototransduction Cascade – when light hits rods and cones

off.

PTC is set of steps that turn it off.

rhodopsin,

A lot of proteins in the disks. One is rhodopsin, a multimeric protein with 7 discs, which contains a small molecule called retinal (11-cis retinal). When light hits, it can hit the retinal, and causes it to change conformation from bent to straight.

transducin

That begins this cascade of events – there’s a molecule in green called transducin made of 3 dif parts – alpha, beta, gamma

phosphodiesterase

Transducin breaks from rhodopsin, and alpha part comes to disk and binds to phosphodiesterase (PDE).

retinal ganglion cell

So bipolar cells turn on. This activates retinal ganglion cell which sends signal to optic nerve to brain.

Photoreceptors

Photoreceptors (Rods and Cones)

specialized nerve

A photoreceptor is a specialized nerve that can take light and convert to neural impulse.

optic discs

Inside rod are optic discs, which are large membrane bound structures – thousands of them. In membrane of each optic disc are proteins that fire APs to the brain.

Cones

Cones are also specialized nerves with same internal structure as rod.

Rods

Rods contain rhodopsin, cones have similar protein photopsin.

Rods are 1000x more sensitive to light

Rods are 1000x more sensitive to light than cones. Better at detecting light – telling us whether light is present, ie. BW vision

color

Cones are less sensitive but detect color (60% Red, 30% Green, 10% Blue)

blind spot

Where optic nerve connects to retina, blind spot – no cones or rods.

trich r omatic theory

Color (cones, trichromatic theory of color vision), form (parvocellular pathway – good at spatial resolution, but poor temporal), motion (magnocellular pathway, has high temporal resolution and poor spatial resolution, no color)

Parallel processing –

Parallel processing – see all at same time; simultaneous processing of incoming stimuli that differs in quality

pressurized sound wave

Need 1) pressurized sound wave and 2) hair cell

sound waves

Air molecules are pressurized and try to escape, creating areas of high and low pressure – known as sound waves

frequency.

How close peaks are is the frequency.

pinna

Hair cells – first hit outer part of ear, known as the pinna. Then go to external auditory meatus (aka auditory canal). Then hit the tympanic membrane (Eardrum)

malleus

As pressurized wave hits eardrum, it vibrates back and forth, causes these 3 bones to vibrate – malleus, incus, and stapes.

oval window

Stapes is attached to oval window (aka elliptical window). As it gets pushed, it pushes fluid and causes it to go around cochlea. At tip of cochea, it can only go back, but goes to the round window and pushes it out.

organ of Corti

Reason doesn’t go back to oval window, is because in middle of cochlea is a membrane – the organ of Corti (includes the basilar membrane and the tectorial membrane).

outer/external ear.

From pinna to tympanic membrane is the outer/external ear.

middle ear

From malleus to stapes, middle ear.

inner ear.

Cochlea and semicircular canals is the inner ear.

Stapes

Stapes – moving back and forth at same frequency as stimulus. It pushes the elliptical window back and forth.

. Organ of Corti

There’s fluid inside the cochlea which gets pushed around cochlea, and comes back around. Organ of Corti splits cochlea into 2.

Organ of Corti

Cross section of Organ of Corti

Upper and lower membrane

Upper and lower membrane, and little hair cells. As fluid flows around the organ it causes hair cells to move back and forth.

hair bundle

The hair bundle is made of little filaments. Each filament is called a kinocilium.

tip link

Tip of each kinocilium is connected by a tip link.

K channel

Tip link is attached to gate of K channel, so when get pushed back and forth they stretch and allows K to flow inside the cell.

spiral ganglion cell

Ca cells get activated when K is inside, so Ca also gets activated, and causes AP in a spiral ganglion cell which then activates the auditory nerve.

cochlea

Brain relies on cochlea to differentiate between 2 different sounds.

basilar tuning –

Brain also uses basilar tuning – there are varying hair cells in cochlea. Hair cells at base of cochlea are activated by high frequency sounds, and those at apex by low frequency sounds.

primary auditory cortex

Only certain hair cells are activated and send AP to the brain – primary auditory cortex receives all info from cochlea.

tonotypical mapping

So with basilar tuning, brain can distinguish dif frequencies – tonotypical mapping.

sensory narrow hearing loss

A surgical procedure that attempts to restore some degree of hearing to individuals with sensory narrow hearing loss – aka nerve deafness

Receiver

Receiver goes to a stimulator which reaches the cochlea. Receiver receives info from a transmitter. Transmitter gets electrical info from the speech processor. Speech processor gets info from microphone.

Types:

Types: Temperature (thermoception), pressure (mechanoception), pain (nociception), and position (proprioception)

Timing:

Timing: Non-adapting, slow-adapting, fast-adapting.

Location:

Location: Location-specific nerves to brain

Adaptation

Adaptation is change over time of receptor to a constant stimulus – downregulation

A mplification

Amplification is upregulation

sensory cortex

This part of cortex is the sensory cortex – contains the homunculus.

proprioception

How can you walk in a pitch black room? You rely on your sense of balance/position –proprioception.

Kinaesthesia

Kinaesthesia is talking about movement of the body. Proprioception was cognitive awareness of body in space. Kinaesthesia is more behavioural.

TrypV1 receptor

In order for us to sense temperature, we rely on the TrypV1 receptor.

conformational change

There are thousands of these in membranes. Heat causes a conformational change in the protein.

3 types of fibres

3 types of fibres – fast, medium, slow.

A-beta fibres -

A-beta fibres - Fast ones are thick and covered in myelin (less resistance, high conductance)

A-delta fibres

A-delta fibres -– smaller diameter, less myelin.

C fibres

C fibres - small diameter, unmyelinated (lingering sense of pain).

Olfaction

Olfaction – Structure and Function

olfaction

Smell is also known as olfaction

olfactory epithelium

Area in nostril called the olfactory epithelium. Separating the olfactory epithelium from the brain is the cribriform plate. Above the plate is an extension from the brain – olfactory bulb – a bundle of nerves that sends little projections through cribriform plate into the olfactory epithelium, which branch off.

olfactory bulb

Zoom in on olfactory bulb

glomerulus

When it binds to receptor, triggers events that cause cell to fire. AP will end up in olfactory bulb. All cells sensitive to benzene will fire to one olfactory bulb – called a glomerulus.

mitral/tufted cell

They then synapse on another cell known as a mitral/tufted cell that projects to the brain.

pheromones

Why do dogs pee on fire hydrant? There are molecules released in the urine, which can be sensed by other animals through the nose – pheromones.

innate response

Pheromone is a chemical signal released by 1 member of the species and sensed by another species to trigger an innate response.

accessory olfactory epithelium

Specialized part of olfactory epithelium in animals – the accessory olfactory epithelium. It sends projections to the accessory olfactory bulb.

vomeronasal system.

Within the accessory olfactory epithelium, you have the vomeronasal system.

basal cells

In vomeronasal system, there are basal cells and apical cells. They have receptors at tips.

amygdala.

Triangle will come in and activate receptor on basal cell here. Basal cell sends axon through accessory olfactory bulb to glomerulus, which eventually goes to the amygdala.

Humans

Humans have vomeronasal organ, but no accessory olfactory bulb.

Gustation

Gustation – Structure and Function

fungiform

Taste buds are concentrated anteriorly on the tongue. Taste buds can be fungiform (anterior), foliate (side), and circumvallate (back).