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1

5 systems and their receptors

-sight=visual=photoreceptors

-touch=somatosensory=specialized endings and free nerve endings

-smell=olfactory=olfactory receptors

-taste=gustatory=taste receptors

-hearing=auditory= hair cells

2

function of our sensory systems

give an organism information about the external world - and the organism's internal state

3

general pathway sensory information through the brain

receptors-->thalamus-->primary sensory cortex-->secondary sensory cortex -->association cortex

4

transduction

-taking the signal from the environment and transforming it into neuronal activity (a signal our system can understand )

-So receptor cells must have ways that the physical stimulus they detect opens or closes ion channels, changing the membrane potential

5

4 types of information about a stimulus that are encoded by the nervous system

1. modality - the type of info encoded by the receptor

2. intensity - the size of thee stimulus

3. duration - how long the stimulus continues

4. location - where the information comes from

6

sensation

bottom-up process by which the physical sensory system receives and represents stimuli at the very basic level of sensory receptors and works up

-info coming from our receptors and traveling up the pathway through the brain

7

perception

Top-down mental process of organizing and interpreting sensory input from experience and expectations

-organizing input and making an experience

8

how do auditory hair cells work

-convert sound energy to neural impulses and send them along to the pathway to auditory cortex

-mounted in the basilar membrane

-mechanoreceptors such that shearing of the two membranes causes physical deflection of the cilia which opens or closes ion channels

9

how are the cochlea and primary auditory cortex organized

cochlea--> hair cells activated by sound, which gets translated into AP-->auditory nerve-->thalamus --> primary auditory cortex

10

does damage to auditory cortex cause deafness

Deafness is usually associated with damage to the ossicles, cochlea or auditory nerve

11

how does the brain calculate where a sound is coming from

Location is calculated using arrival time and volume differences between the 2 ears.

12

what are the functions of the olfactory and gustatory systems

-olfactory= smell; detects airborne chemicals

-gustatory = taste; responds to chemicals in the mouth

13

how does an olfactory receptor work

Each olfactory receptor responds to more than one chemical or odor

14

how does the brain encode the identity of an odor

through the pattern of activity of many neurons

15

what is unusual about the olfactory pathway

-does not go through the thalamus on its way to primary olfactory cortex

16

neural pathway of the gustatory pathway

-taste receptors-->thalamus-->primary gustatory cortex

17

how do we sense different types of tastes (including hot)? what are the different mechanisms for sensing

-Five primary tastes
◦ Sweet, Salty, Sour, Bitter, and Umami

-Salty and sour don’t have receptors, they merely act on ion channels directly

-Taste receptors are individually variable, continually replaced, and decline with age

-Heat like jalepenos (capsaicin) not detected by taste receptors, but pain receptors

18

how does satiation change activity in the brain in the gustatory system

-repeated presentation decreases the taste and how more we want with time

-activity decline with increasing presentation of the chocolate bc habituation is occurring so it does not activate gustatory cortex as much

19

anosmia

-inability to smell

20

3 somatosensory systems

-exteroreceptive
-proprioceptive
-interoceptive

21

what do somatosensory receptors respond to

-exteroreceptive: touch/pressure (mechanical stimuli); temperature (thermal stimuli); pain

-proprioceptive : body position

-interoceptive: body condition (temp and blood pressure )

22

ageusia

-inability to taste

23

how is the somatosensory system organized

-Different types of receptors detect different types of somatosensory stimuli

-some respond to pressure
-some to being squish

24

what does the homunculus tell us about the somatosensory system

a representation of the size of representation of the various size of our touch receptors

25

2 types of photoreceptors

-cones: high acuity in good light/color

-rods: high sensitivity in dim lighting; in dark

26

fovea

No receptors where the ganglion cell axons exit the eye into the optic nerve

27

blindspot

-At the center of the retina
-The high density of receptors allows high acuity --Sort of like increasing the number of pixels of resolution

28

neural pathway from the retina to primary visual cortex

retina-->photoreceptors-->rods and cones-->optic nerve --> thalamus (LGN)--> primary auditory cortex

29

retinotopic means ?

this little space stays next to this little piece of space while it travels to V1

-to get a proper view (unified view) of what is in front of us

30

what is an on-center cell?

-light in center: activated

-light in surround: deactivated

-light covering entire receptive field: not as active, inhibited

-makes our visual system really good at detecting edges