npb 110b midterm II

free nerve endings (stimulus, location, structure, adaptation)

stimulus: touch + pressure
location: hair roots, under skin surface
structure: unmyelinated nerve endings
adaptation: variable

meissner’s corpuscles (stimulus, location, structure, adaptation)

stimulus: flutter, stroking
location: skin superficial layers
structure: encapsulated in connective tissue
adaptation: rapid

pacinian corpulsces (stimulus, location, structure, adaptation)

stimulus: vibration
location: deep skin layers
structure: encapsulated in connective tissue
adaptation: rapid

ruffini corpulsces (stimulus, location, structure, adaptation)

stimulus: skin stretching
location: deep skin layers
structure: enlarged nerve endings
adaptation: slow

merkel receptors (stimulus, location, structure, adaptation)

stimulus: steady pressure, texture
location: superficial skin layers
structure: enlarged nerve ending
adaptation: slow

somatosensory thalamus nucleus

ventral posterior complex (VPM, VPL)

ventral posterior lateral nucleus encodes:

sensory info from body

ventral posterior medial nucleus encodes:

sensory info from face

somatosensory cerebral cortex target

primary somatosensory cortex (S1)

somatosensory lobe

parietal lobe (S1)

2 pathways of the somatosensory system

1. dorsal column pathway

2. spinothalamic pathway

dorsal column pathway (somatosensory) encodes

mechanoreceptors, propriceptors

dorsal column pathway (somatosensory) crosses at:

brainstem/medulla

spinothalamic pathway (somatosensory) encodes:

thermoreceptors, nociceptors

spinothalamic pathway (somatosensory) crosses at:

dorsal root axon

what happens when photoreceptors are exposed to light

1. light decomposes the pigment

2. Na+ channels are closed

3. photoreceptors hyperpolarize

4. decreased glutamate release

how horizontal cells respond to light vs dark

light: reduced glutamate from photoreceptors → hyperpolarize → no inhibition on photoreceptor

dark: increased glutamate from photoreceptors → depolarize → inhibits photoreceptor

what happens when ON-center bipolar cells are exposed to light

less glutamate from photoreceptors → K+ channels close → depolarize → send signal

what happens when OFF-center bipolar cells are exposed to light

less glutamate from photoreceptors → hyperpolarize → no signal sent

function of amacrine cells

send signal from photoreceptors to horizontal cells OR directly to ganglion cells

what is the main thalamic nucleus of the visual system

lateral geniculate nucleus (LGN)

what do magnocellular/M cells encode, and from rods or cones?

motion and low light (rods)

what do parvocellular/P cells encode, and from rods or cones?

color and fine detail (cones)

what do rods detect

dim light, motion

what do cones detect

color, fine detail

where are rods and cones most concentrated in the eye

the fovea

which lobe is involved in the visual system

the occipital lobe

what is the main cortex of the visual system

primary visual cortex (V1)

which layers of the LGN are P cells

upper 4

which layers of the LGN are M cells

lower 2

where information in the visual system crosses over

at the optic chiasm, before the thalamus

T/F: information in the right visual field is processed in the right side of the brain

F

what information do simple cells encode

position sensitivity

what information do complex cells encode

motion sensitivity

hypercolumn definition + the information it contains

2 adjacent ocular dominance columns that can detect all orientations in a specific area of the visual field (for each eye)

what are the two pathways information can travel in after the primary visual cortex/V1

ventral, dorsal

where does the ventral pathway project to after V1 (lobe + name)

inferotemporal cortex (temporal lobe)

what information (M or P cell info) travels down the ventral pathway after V1

M cell info

where does the dorsal pathway project to after V1 (lobe + name)

middle temporal visual area/MT (parietal lobe)

what information (M or P cell info) travels down the dorsal pathway after V1

P cell info

what information is processed in the inferotemporal cortex after V1

object recognition (complete forms)

what information is processed in the middle temporal visual area (MT) after V1

image motion + location (mostly direction-sensitive cells)

where does information cross in the auditory system

a large number of cross-connections, before the thalamus

what frequencies at detected at the base of the basilar membrane

high frequencies

what frequencies at detected at the apex of the basilar membrane

low frequencies

what are two ways to calculate sound localization

interaural level differences (ILDs) and interaural time differences (ITDs)

where are ITDs (time) used/occur in the auditory system

medial superior olive (MSO)

how are ITDs used in the auditory system

neurons respond when excitatory signals from the ears arrive at the same time, takes a shorter path/is closer to the ear that is closer to the sound

where are ILDs (intensity) used/occur in the auditory system

lateral superior olive/MNTB

how are ILDs used in the auditory system

side with stim excites that side’s LSO and inhibits other side’s LSO via the MNTB

side with stronger stim’s excitation > other side’s inhibition of that side

what is phase locking

detects temporal info/ITDs in lower frequencies; same location on sine wave every period

auditory thalamus nucleus

medial geniculate nucleus (MGN)

auditory cerebral cortex target

auditory cortex (A1)

lobe involved in auditory system

temporal lobe

what are isofrequency bands in the auditory system

areas where neurons with similar frequency preferences are grouped together

what is conductive hearing loss

sound is unable to travel efficiently due to damage to the tympanic membrane or the ossicles

what is sensorineural hearing loss

sound nerve pathways damaged and unable to transmit

tympanic membrane function

convert sound waves to mechanical energy (vibration)

ossicles function

translate vibrational energy into fluid motion in the cochlea

what are the olfactory sensory receptors

olfactory receptor neurons (ORNs)

T/F: an ORN (olfactory) can respond to multiple odorants

T

T/F: an ORN (olfactory) can have multiple receptor proteins

F

how is taste transduced in the gustatory system

salty/sour: via ion channels on tongue

sweet/umami/bitter: via G-protein coupled receptors

where does information cross in the olfactory system

it doesn’t; ipsilateral

where does information cross in the gustatory system

it doesn’t; ipsilateral