Neurobiology Final

Front 1

Frequency

Back 1

number of cycles per second of air pressure chane passing a point in space. Measured in Hertz

Front 2

The higher the frequency...

Back 2

the higher the perceived pitch. Doubling frequency raises the sound an octive.

Front 3

pinna

Back 3

external part of the ear, helps collect sound and is more sensitive to sounds from ahead than behind. The convolutions help localize sound

Front 4

Tympanic membrane

Back 4

the "eardrum", fluctuations in the air pressure cause the membrane to vibrate, vibrations match the frequency of the sound

Front 5

3 ossicles

Back 5

"ear bones"; they transmit vibrations from the eardrum to the oval window membrane
they amplify the sound

Front 6

attenuation reflex

Back 6

the onset of a high intensity sound causes muscles around the ossicles to contract reducing the movement of the ossicles. Helps prevent loud sounds from saturating the auditory receptor cells in the inner ear

Front 7

oval window

Back 7

the membrane covered hole on the wall of the coclea

Front 8

cochlea

Back 8

the part of the inner ear concerned with hearing. Ossicle induced movements in the oval window move fluids in the cochlea which trigger auditory transduction

Front 9

3 cochlear chambers with fluid:

Back 9

scala media between Reissner's membrane and the basilar membrane.

Front 10

Place coding

Back 10

the location of the resonating membrane (on the cochlea) informs the brain of the sound frequency

Front 11

Shaft vs apex

Back 11

higher frequency is closer to the shaft where it is stiff. Lower frequency is at the apex where the basiler membrane is wide and floppy

Front 12

Auditory transduction cascade

Back 12

at rest, sterocilia stand vertically and channels are partially open. When movements in the basilar membrane cause the longest row of sterocilia to move away from others, the tip links are stretched and pill the channels wider open. When the logest row of stereocilia bends toward the others, tension on the tip links is reduced and the channels close

Front 13

inner hair cells vs. outer hair cells

Back 13

the inner hair cells account for 95 percent of the spriral ganglion cells, the outter only 5 percent.

Front 14

Amplification of low intensity sounds

Back 14

comes from the outer hair cells. the motor proteins on the outer hair cells compress during a depolarization which leads to the inner hair cells sterocilia bending more--> greater depolarization

Front 15

Perceived intensity of sound depends on:

Back 15

1. the rate of spiral ganglion cell firing (amount of NT released)
2. the number of spiral ganglion cells that are firing

Front 16

characteristic frequency

Back 16

the frequency to which the auditory neuron is most sensitive

Front 17

tonotpic mapping or tonotopy

Back 17

the systematic relationship between location and chaaracteristic frequency is perserved in subsequent stages along the auditory pathway

Front 18

phase locking

Back 18

the consistent firing of spiral ganglion cells at the same phase of a sound wave, arising from the presynaptic hair cells membrane potential that follows the oscillations in sound pressure

Front 19

Primary pathway from cochlear nuclei to cortex:

Back 19

each ventral cochlear nucleus sends axons to both superior olives. The superior olive localizes sounds in the horizontal plane.

Front 20

Superior olive

Back 20

first structure in the auditory pathway with binaural neurons, which localize the sounds in the horizontal plane

Front 21

interaural time delay

Back 21

sound coming from one side of the body will reach the ear on that side before reaching the other ear. Only works for frequencies with wavelengths wider than the width of the head (ie low frequencies)

Front 22

Delay line

Back 22

some birds have delay lines so that the spike from the two ears arrive at the same time and summate for a larger EPSP

Front 23

Interaural intesity difference

Back 23

the head casts a sound shadow such that the ear in the shadow detects a lower intensity sound

Front 24

EE cells

Back 24

neurons in the superior olive that are moderately excited by sound from either ear, and maximally excited when both ears are stimulated (aka respond best to sound on midline).

Front 25

EI cells

Back 25

maximal response when sound comes from the excitatory side and minimal response from the inhibitory side

Front 26

Localization of sound in the vertical plane

Back 26

uses the convolutions of the pinna to assess elevation of sound. Doesnt require both ears

Front 27

A1

Back 27

primary auditory cortex

Front 28

isofrequency bands

Back 28

strips of neurons with similar characteristic frequencies

Front 29

A1 output

Back 29

to higher auditory cortical areas that process very complex sounds (aka Wernickes area)

Front 30

Lateral Line system

Back 30

lateral line receptors are hair cells with cilia embedded in a gelatinous material (cupula). When the cupula moves, the cilia are bent and trigger a depolarizing response

Front 31

cupula

Back 31

gelatinos material in the lateral line receptors. The cilia of the hair cells are embeded in the cupula

Front 32

Vestibular system

Back 32

monitors the position and movement of the head and communicates thaat position to motor centers in the brain. helps maintain body balance

Front 33

Vestibular labyrinth in the inner ear

Back 33

connected to the cochlea and fulled with the same endolymph

Front 34

Otolith organs detect:

Back 34

changes in head angle and linear acceleration

Front 35

Uticle

Back 35

layer of hair cells (macula) parallel to the ground while the person is standing (in otolith organs)

Front 36

Saccule

Back 36

macula perpindicular to the ground while the person is standin (in otolith organs)

Front 37

macula

Back 37

hair cells in the otolith organs

Front 38

Otoliths

Back 38

ear stones in the gelatinous cap of the otolith organs

Front 39

transductin cascade for vestibular hair cells:

Back 39

each mechanically gated K channel on a sterocilium is connected by an elastic top link to the channel adjacent. Sterocilia straight up: channels partially open. etc
K enters the endolymh--> depolarization

Front 40

Macular orientation of hair cells

Back 40

each hair cell selects for a specific deirection of head movement. The entire population of hair cells covers all possible direction of linear movement.

Front 41

Hair cells in the semiciruclar canals:

Back 41

filled with endolymph, stereocilia project into the gelatinous capula. Upon head rotation canal wall rotates but endolymph initially stays still causing fluid motion opposite to head motion. The capula moves with the fluid and bends th ehair cells sterocilia.

Front 42

Response to velocity change in teh vestibular hair cells:

Back 42

1. if velocity remains constant, then the otliths and the cupula return to resting potentials
2. the hair cells also adapt to the sustained stimuli (never return fully to their resting potential)

Front 43

Central vestibular pathway

Back 43

hair cells release excitatory NT onto the dendrites of the Scarpa's ganglion cells whose axons form the vestibular nerve. the vestibular nerve projects to the cerebellum which coordinates motor activites and to the vestibular nuclei

Front 44

vestibular nuclei project to:

Back 44

spinal cord motor neurons to control muscles in the legs, also motor neurons in trunk and neck that orient head, motor neurons that move eyes, and thalamus which projects to the primary somatosensory cortex and the primary motor cortex

Front 45

vestibule-ocular reflex

Back 45

enables you to keep your eyes fixed on a point even when your head is moving. Works in complete darkness

Front 46

soma

Back 46

the body of an organism

Front 47

somatic sensations

Back 47

all the sensation that are not the five sense. Aka sensations of our skin, muscles, joints, and internal organs; touch, pain, and temperature

Front 48

touch transduction by mechanoreceptors

Back 48

mechanical deformation of cell membrane--> channels open--> depolarization--> action potential

Front 49

Mechanoreceptors nerve endings

Back 49

unmyelinated and encapsulated by special non-neural tissues which determine types of tactile stimuli each cell type is sensitive to

Front 50

Mechanoreceptor channels

Back 50

gated cation channels which probably include TRP channels

Front 51

Somatic sensory receptors

Back 51

cell bodies in the dorsal root ganglia, they are pseudo-unipolar. The axons of these are called primary afferents. The proximal side of these axons enters the dorsal side of the spinal cord

Front 52

receptive field size increases with...

Back 52

depth of skin

Front 53

dermatome

Back 53

area of skin innervated by each spinal nerve

Front 54

touch pathway

Back 54

alpha and beta axons carrying touch information enter the dorsal horn of the spinal cord:
one branch goes deeper into the dorsal horn to initiate or modify reflexes. the other branch follows the dorsal column to go to the brain.

Front 55

projection to the cortex through the dorsal column-medial lemniscal pathway:

Back 55

primary afferents ascend ipsilaterally in forsal column and synpase on to second order neruons in the brain. Second order neurons cross over in the brain stem then project to the ventral posterior lateral nucleus of the thalamus.

Front 56

S1 also called:

Back 56

brodmanns area 3b

Front 57

S1 organization

Back 57

neocortex with 6 layers: thalamus to layer IV, layers II and III to orther cortical areas, layers V and VI to subcortical areas

Front 58

columnar organization of S1

Back 58

by receptor type and location: rapidly adapting neurons and slowly adapting neurons aligned in columns

Front 59

somatotopy

Back 59

the orderly projection of body parts onto a somatosensory nucleus or cortical area

Front 60

Experiments that show somatotopy

Back 60

1. electronically stimulating across s1 and observing what area of the body feels a touch sensation
2. also stimulating the body and recording neural activity in s1

Front 61

homunculus:

Back 61

illustrated the relative body representation in the somatosensory cortex. there is over representation of body parts with high densities of receptors

Front 62

lateral inhibition does what for the s1 neurons?

Back 62

enhances spactial contrast between second order neurons and neighboring neurons. This enhancment in spatial contrast improves two point discrimination

Front 63

area 1

Back 63

texture

Front 64

area 2

Back 64

size and shape

Front 65

beyond s1 the stimuli that neurons perfer becomes...

Back 65

more complex. Rf are larger and some cells are direction selective

Front 66

areas 5 and 7

Back 66

posterior parietal cortex: integrates tactile inpu, proprioceptive input, and visual information to identify objects. also sends sensory info to motor cortex for movement

Front 67

sensory cortical plasticity:

Back 67

if the input to a cortical area is underused or removed, surrounding areas of cortex may take over that region. If the input is frequently activated then the rfs may expand over time

Front 68

nocioception

Back 68

sensory transduction process that provides the signals that tigger pain

Front 69

nocioceptors:

Back 69

DRG cells with free, branching, unmyelinated nerve endings

Front 70

hyperalgesia:

Back 70

increased sensitivity to pain stimuli. caused by chemicals released or synthesized when tissues are damaged. chemicals include bradykinin, prostoglandins, and substance P which induces histamine relasese

Front 71

Nocioceptor input into the spinal cord

Back 71

nocioceptors signal to the spinal cord through A and C fibers which conduct spikes at different speeds. These primary afferents enter the dorsal horn and branch immediately and quickly synapse on to second order neurons using glutamate and substance P as excitatory transmitters

Front 72

pain pathways to the cortex

Back 72

second order pain neurons crossover immediately and ascend through the spinothalamic tract. The the thalamus the pain touch pathways ocupy different parts of the VPL nucleus and the pain pathway occupies additional thalamic regions.

Front 73

nocioceptors in the face pathway to the cortex

Back 73

go through the trigeminal nerve to reach second order cells in the brain stem which corssover immediately and ascend to the VPM and other thalamic regions

Front 74

afferent regulation:

Back 74

pain evoked by nociceptors can sometiems be reduced by simultaneous activation of touch receptors. this is why rubbing the skin around an injury can reduce the pain

Front 75

gate theory of pain

Back 75

an interneuron serves as a gate that can permit or block signal transmission from the c fibers to second order neurons

Front 76

reducing pain perception via descending regulation

Back 76

certain emotional and behavioral states activate periaqueductal gray matter neurons, which activate a descending pathway that uses serotonin and endorphins t osuppress the activity of nociceptive neruons in the dorsal horns

Front 77

reducing pain pereption via endorphins

Back 77

endorphins are endogenous morphine like substance that activate opioid receptors. Activated opioid recpeotrs depress the activity of neurons in the pain pathway by supressing the release of glutamate from presynaptic terminals and hyperpolarizing the postsynaptic neurons

Front 78

thermoreceptive nerve endings

Back 78

free unmyelinated nerve endings

Front 79

TRP channels

Back 79

30 have been identified and all are cation channels with six transmembrane domains

Front 80

adaptation in thermoreceptors

Back 80

the response amplitude of thermoreceptors is highest during and shortly after temperature changes. The temperature pathway is virtually identical to the pain pathway however the two are parallel pathways so info is kept seperate

Front 81

electroreception

Back 81

process of sensing electric fields

Front 82

two kinds of electric field sensing abilities

Back 82

1. passive electric sense: can sense an electric field but cannot generate one of their own (sharks)
2. active electric sense: can generate an electric field of their own (electric eel)

Front 83

Electric fields

Back 83

generated by seperation of positive and negative charges. to detect an electric field there must be current and flow of charges

Front 84

Electric organ discharge (EOD)

Back 84

readily observable electrical signal generated by the excitable cells of an electric organ. Behavioral significance: electrolocation, electrocommunication, and stunning prey/warding off predators

Front 85

ampullary organs:

Back 85

low frequency sensitive receptors. all electric fish have them and they detect weak electric fields. its a jelly lumen with high K+

Front 86

ampullae of lorenzini

Back 86

can detect the earth's magnetic field

Front 87

tuberous organs

Back 87

high frequency sensitive receptors. used for electrolocation and electrocommunication.

Front 88

Electric organ discharge (EOD)

Back 88

readily observable electrical signal generated by the excitable cells of an electric organ. Behavioral significance: electrolocation, electrocommunication, and stunning prey/warding off predators

Front 89

ampullary organs:

Back 89

low frequency sensitive receptors. all electric fish have them and they detect weak electric fields. its a jelly lumen with high K+

Front 90

ampullae of lorenzini

Back 90

can detect the earth's magnetic field

Front 91

tuberous organs

Back 91

high frequency sensitive receptors. used for electrolocation and electrocommunication.