Introduction To Neuroscience (The Changing Brain)

Front 1

During Gastrulation

Back 1

During gastrulation, the germ layers of an embryo are formed and the body plan of the mature organism is established. Movements on a massive scale allow cells to establish great complexity from a very simple starting form.

Front 2

Archenteron

Back 2

is the primitive gut of the embryo and is completely surrounded by endoderm which gives rise to the digestive tracts and associated structures

Front 3

Formation of the Notochord

Back 3

is a central event in gastrulation it is a distinct cylinder of mesodermal cells that condenses atthe midline of the mesoderm that extends from the mid anterior to the posterior aspect of the embryo the notochord sends inductive signals to the above ectoderm cells to diferentiate into neural precursor cells so the neural plate a groove in the neural plate forms and its walls come together forming the neuronal tube

Front 4

The Entire nervous system develops from what structure?

Back 4

the walls if the Neural Tube

Front 5

Synaptic plasticity can be thought to of the ability to modify neural circuitry, generally speaking what are the three mechanisms by which this can happen

Back 5

1. by modifying the strength and/ or efficacy of synaptic transmission at the pre existing synapses
2.by eliciting the growth of new synaptic connections or the pruning away of the existing ones
3. by modulating the excitability properties of the individual neurons

Front 6

define synaptic facilitation

Back 6

is the result of two or more actions potentials arrive invades a presynaptic terminal in very close to each other you can get double the response with the same simulation this has to do with the build up of calcium because the mechanisms for reuptake of calcium is much slower than that of the entry of CA2+ into the presynaptic terminal

Front 7

define synaptic depression

Back 7

if you simulate for a longer period of time you will see a decrease in strength of AP this is due to the depletion of the synaptic vesicles until synaptic supply is replenished

Front 8

What species was used in experiments studying the hippocampus

Back 8

marine mollusk aplysia withRepetitive, unilateral stimulation of Aplysia induces long-term sensitization (LTS) of ipsilaterally elicited siphon-withdrawal responses

Front 9

Define Short term Sensitization in neural development

Back 9

Short-term sensitization (lasting from seconds to minutes) relies on covalent modification of pre-existing proteins. it is due to pka development enhancement of glutamate release from the presynaptic terminals of sensory neurons onto motor neurons

Front 10

define long term sensitization

Back 10

it is due to changes in gene expression of proteins that change pka activity and lead to changes in synaptic growth Creb is active and binds to cAMP responsive elements CREs increase the rate of transcripton of downstream genes

Front 11

Define LTP

Back 11

long term potentiation- is a activity dependent experience dependent long last increase in strength of chemical synapses of neurotransmission that is a crucial mechanism in learning and memory seen in the CA1 region and CA3 region of the hippocampus the dendrite on the pyramidal cells in CA3 will cause an EPSP on CA1

Front 12

Experimentally how would you demonstrate LTP

Back 12

repetitive tetanic stimulation of synapsis or directly depolarizing the cell while at the same time continuing low frequency synaptic activation. NMDA (N-methyl-d-aspartate) receptors are permeable to Ca by pore is blocked by Mg ions and no current will flow during low current frequency synapti transmission glutamate released by schaffer collaterals bind to both NMDa and AMPA during resting potential only AMPA is producing current however during repetitive simulation Mg is expelled out of the core and current will flow

Front 13

How is LTP have associatively and specific

Back 13

specific because it can only happen at sites where there is active release of glutamate and associative because both receptors must be present CaMKII and PKC play a role in the induction of LTP

Front 14

what is the purpose of LTD

Back 14

to reduce LTP to baseline the mg block is not 100% effective so there is still a small influx of calcium the requirements are the activation of NMDA and Ca concentration caused by protein phosphatases therefore increase the calcium concentration in postsynaptic terminals reducing the effect of LTP low rise in ca binds to cam activating pp2b a dephosphorylates inhibitor

Front 15

what are some alternative theories for LTD and LTp

Back 15

the insertion of AMPA receptors into synaptic membrane (LTP) and removal of AMPA receptors

Front 16

define Gastrulation

Back 16

the formation of the three germ layers during embroyo development

Front 17

What cell bodies derive from the neural crest

Back 17

all the cell bodies of the PNS

Front 18

Describe the experiments in the 1930s witg Mangold and Spellmann

Back 18

they discovered indiction during tranplatation experiments in which they inplanted small pieces of tissue on another pregastrulate stages and found when tissue from DBL they found that the recieving embroyo was derived from host tissue

Front 19

What is the role of retonic acid

Back 19

it is a derivative of vitamin A activates a unique class of transcription factors that modulate the expression of downstream genes

Front 20

NAme the two most importance peptide hormones that has to deal with neural induction

Back 20

fibroblast growth factor (FGF) and transforming growth factor (TGF)

Front 21

The Wnt signal-transduction pathway influences neural cell fates by

Back 21

causing the degradation of a cytosolic protein complex that cause the translocation of B catenin from the cytoplasm to the nucleusand forms interactions with dna binding transcription factor called LEF/TCF that effects the expression of a number of downstream genes

Front 22

Once the neural tube has formed, the next step in the formation of the nervous system is

Back 22

neurogenesis

Front 23

The most prominent means by which migrating neurons move through the CNS is by

Back 23

following radial glia fibers postmitotic neurons bind to the processes of glial cells through the thickening cortical wall

Front 24

Migration of neural crest cells

Back 24

arise from sensory placodes and neural crest during the late stages of neurulation in the dorsal ectoderm the cells begin a neuroepithelial cells thus have cellular junction and adhesive interactions to keep in place to move them you must downregulate the expression of those genes BHLH and SNail1 and snail2

Front 25

what is The structure that causes formation of neural tissue in an overlying germ layer is called the

Back 25

notochord

Front 26

the initial differentiation of neuron and glia starts from which type of cell

Back 26

precursor cells that are located in the ventricular zone which is the innermost cell layer surrounding the lumen of the neural tube and leads to with stem cells are neuroblast(asymmetric) stem cells (symmetric)

Front 27

The peptide hormone that induces motor neuron development via the cooperative binding of patched and smoothened is called

Back 27

indirect method two surface receptors smooth and patched w/o shh it is inhibitory modulates a group of transcription factor Gli 1 ,2 3 only 3 is active which represses when SHh is active 1 is active or gli 2 makes it ways to the nucleus and binds to the patch protein

Front 28

describe the BMP receptors

Back 28

act on serine and threonine residues (SEr, Tht kinases

Front 29

Which of the following statements about embryonic stem cells (ESCs) is correct?

Back 29

ESCs are normally derived from pre-gastrula stage embryos.

Front 30

Name and describe the components of the growth cone

Back 30

Lamellipodia undergoes motion like a stingray and filopodia extends out like thin spikes that probes the environement looking for the direction in which axons will grow

Front 31

define the molecular mechanism for axon growth cones

Back 31

dynamic polymerization and depolymerization sets the direction of growth cone movement by generating local forces cams cadherins and ephrins mediate the growth processes

Front 32

name four components that play an important role in the establishment of axon tracts and in growth cone navigation

Back 32

Cell adhesion molecules
b. Extracellular matrix components
c. Cytoskeletal proteins

e. Second messenger systems

Front 33

Neurotrophic factors

Back 33

play a role in adjusting the size of neuronal populations to an appropriate number

Front 34

Roger Sperry’s chemoaffinity hypothesis

Back 34

is supported by the orderly reinnervation of the frog optic tectum by regenerating retinal ganglion cells found "identification tags" via systems of gradients

Front 35

Extracellular matrix molecules serve as ligands for

Back 35

integrin receptors/ integrins are a family of receptor molecules found on growth cones that bind to cams such as laminin in fibronectin

Front 36

Actin and tubulin dynamics in growth cones are influenced or regulated by

Back 36

a. intracellular calcium.
b. voltage-gated calcium channels.
c. intracellular calcium stores.
d. TRP channels

Front 37

The two molecules that are particularly central to the general formation of CNS synapses are _______ and _______.

Back 37

a. neurexin (helps locollize synaptic vesicles docking protein proting adhesion ; neuroligin post the clustering of receptors and channel

Front 38

Axon guidance cues can affect

Back 38

a. actin and tubulin dynamics.
b. the complement of receptors and channels at the surface of the plasma membrane.
c. the expression of different neural genes.

Front 39

--------------------------------------------------------------------------------
Elongation of the axon proper (as it trails the growth cone) is most directly a consequence of

Back 39

tubulin polymerization

Front 40

The chemical signaling molecule Sema3A

Back 40

causes growth cones to collapse and neural processes to resorb

Front 41

The sweet transduction system involves

Back 41

a. heterodimeric G-protein–coupled receptors.
b. activation of G-proteins.
c. activation of phospholipase C.
d. IP3 activation of TRPM5 channels.

Front 42

In humans, the olfaction-responsive brain area that responds to multimodal stimuli (such as the sight and smell of food) is located in

Back 42

orbitofrontal cortex.

Front 43

list the various components of the olfactory transduction process

Back 43

1.Golf G-protein
2. Adenylyl cyclase III
3. cAMP-gated ion channel
4.Calcium-activated chloride channel
5.Voltage-gated sodium channel

Front 44

Name the following iof the five principal tastants sensed by taster bud cells

Back 44

b. Bitter
c. Sour
d. Sweet
e. Salty

Front 45

Which of the three chemosensory systems relies on G-protein–coupled receptors

Back 45

Olfactory system only (odorants)
b. Gustatory system only (tastants)

Front 46

Sour substances activate taste cells by

Back 46

the depolarization of protons entering taste cells.

Front 47

Olfactory receptors are found at the highest concentration in

Back 47

the olfactory cell cilia.

Front 48

Richard axel and linda buck discovered what

Back 48

the odorant receptor gene family the three assumptions that they made was that ORN must be G protein coupled receptors second they will exclusively expressed in the nasal epithelium and third there will be a large number of them

Front 49

the olfactory bulb

Back 49

recieves axons from cranial nerve I and provide the relay station to the rest of the brain main target is the three layered pyriform cortex in the temporal lobe

Front 50

what are the molecular mechanism for taste tranduction of A. salt, b- sour c. sweet, d. amino acids e. bitter

Back 50

1. amiloride sensitive Na channels
2. H+ sensitive trp channel
3.sweet- g protein protein couple
4. "
5. G protein witj gustducin which binds IP3 to TRPM5 channels

Front 51

A topographic map representing the body’s sensory surface is first found in

Back 51

nucleus cuneatus plus nucleus gracilus.

Front 52

The “dorsal columns” refer to the

Back 52

bundles of axons running in the dorsal aspect of the spinal cord.

Front 53

define dermatomes

Back 53

a. Dermatomes are defined by the area of skin innervated by each spinal nerve.

c. Knowledge of dermatomes can aid in determining the level of a spinal lesion.
d. Dermatomes for touch, pressure, and vibration are larger than those for temperature and pain.
e. The cutaneous areas of the fronts of the legs and the backs of the legs are in different dermatomes.

Front 54

a. Pacinian afferent
b. Meissner afferent
c. Ruffini afferent
d. Merkel cell
e. Hair follicle receptor

Back 54

a. encapsulated mechanosensory receptor specialized for the detection of high frequency vibrations
b. specialized for detectionof fine touch and texture
c. sensitive to stretch least understood
d. same as meissner

Front 55

define mesencephalic trigeminal nucleus

Back 55

well defined cluster of neurons lying in the lateral extent of the central gray matter of the midbrain where first order propriceptive neurons of the face are located

Front 56

Golgi tendon organs are most sensitive to

Back 56

c. tension.

Front 57

The fastest conducting of the following sensory fibers is the

Back 57

group Ib mechanoreceptors.

Front 58

muscle-spindle-based proprioceptive system

Back 58

In-parallel alignment with extrafusal muscle fibers
c. Mechanically gated ion channels
d. Group I and II afferent axons
e. Innervation by γ motor neurons

Front 59

One would expect to find the smallest two-point discrimination threshold on the

Back 59

e. fingers.

Front 60

The internal capsule conducts sensory information

Back 60

from the thalamus to the cortex.

Front 61

The right nucleus gracilus projects to (i.e., sends action potentials to) the

Back 61

. left thalamus.

Front 62

Somatosensory neurons in the DRG normally transmit information

Back 62

from the skin to the spinal cord.

Front 63

The earliest evidence suggesting a columnar organization within neocortex was provided by

Back 63

Vernon Mountcastle

Front 64

How many degrees of freedom do the body have

Back 64

6 degrees of freedom

Front 65

X Axis-
Y- Axis
Z- Axis

Back 65

Roll
Pitch
Yaw

Front 66

Where is the labyrinth located and what are the components

Back 66

buried deep in temporal bone consist of two otolith organs the utricle saccule and three semicircular canals

Front 67

Neurons in the ventral posterior nuclear complex of the thalamus

Back 67

integrate multimodal sensory information.
b. respond to rotation in the dark.
c. receive visual and proprioceptive inputs.
d. are likely involved with the perception of extrapersonal space.

Front 68

Which of the following organs is most sensitive to a change in pitch of the head?

Back 68

Saccule

Front 69

Which of the following structures is designed to detect angular acceleration?

Back 69

c. Semicircular canals

Front 70

Squirting cold water in the ear of a reclined person will elicit eye movements

Back 70

c. characteristic of different neurological deficits.

Front 71

Patients with severe bilateral vestibular damage exhibit what kind of deficits

Back 71

a. a permanent deficit in visually fixating while moving.
.
c. postural instabilities.
d. impaired balance in low-light conditions.
e. difficulty walking on uneven surfaces

Front 72

The “electrical resonance” of vestibular hair cells

Back 72

involves a very rapidly activated calcium-dependent potassium channel.

Front 73

“sensory epithelia” in the ear

Back 73

a. They have tight junctions.
b. Their epithelial hair cells have a polarized orientation.
c. They are embedded in structures that enable different kinds of mechanoreception.

Front 74

VOR is a mechanism for

Back 74

stabalizing gae during head movement

Front 75

Hair cell polarity is important for

Back 75

cochlear signaling mechanisms.
b. semicircular canal signaling mechanisms.
c. otolith organ functioning.
d. tip-link transduction mechanisms.

Front 76

Which cells convey vestibular signals from the periphery to the CNS?

Back 76

Cells in Scarpa’s ganglion

Front 77

Neural pathways and signals mediating the VSR excite which type of muscle

Back 77

excite extensor muscles

Front 78

Which of the following statements about the hair cells on the three distinct hair-cell bearing structures of the labyrinth is true?

Back 78

Each structure has a distinct pattern of hair-cell orientation.

Front 79

The vestibular system is able to detect

Back 79

translational acceleration in any direction.
b. rotational acceleration in any direction.
c. orientation of the head with respect to gravity.

Front 80

Right unilateral vestibular damage

Back 80

e. causes a fixation-while-moving deficit from which patients generally recover.

Front 81

mechanotransduction mechanism of vestibular hair cells

Back 81

A calcium-dependent slippage mechanism may allow for adaptation of tension on the tip links.

Front 82

Both the cochlea and the labyrinth

Back 82

use hair cells in mechanotransduction.

Front 83

The semicircular canals are largely insensitive to linear acceleration because

Back 83

linear forces are the same on both sides of a canal.

Front 84

in the utricle and saccule the sensory epithelium or macula conisist of what

Back 84

hair cells and supported cells overlying the hair cells and their stereocilia is gelatinous layer above this layer id otolithic membrane in which embedded crystals or CaCO3 otoconia

Front 85

how does the tilt of the head or linear acceleration lead to deplorization or hyperpolariation of hair cells

Back 85

the otoconia make the otolithic membrane much denser and gravity causes a shearing motion between that and the macula that displaces hair bundles which are embedded in the lower gelantinous layer the displacement generates a receptor potential in the hair cells that are dependent on the direction of tilt direction in the direction of kinocilium depolarizes the cell potassium channels to open results in neurotransmitter release

Front 86

the otolith organs are more concerned with

Back 86

head translations and orientation in respect to gravity

Front 87

each of the three semi circular canals has at its base a bulbous expansion called the ________ which

Back 87

ampulla which houses sensory epithelium or crista that contains the hair cells

Front 88

What are the functiona or operating feature of the outer ear?

Back 88

Boosting sound pressure level as it enters the ear
b. Filtering sound in an adaptive manner based on source elevation
Optimally transmitting sounds in our range of vocalizations
e. Boosting frequencies by means of passive resonances

Front 89

In which of the following brain regions are the intensities (not the phases) of impinging sound waves compared in order to determine the location of sound sources?

Back 89

lateral superior olive

Front 90

In comparison to inner hair cells, outer hair cells

Back 90

are more strongly innervated by efferent fibers

Front 91

Cells that respond to specific combinations of sound frequencies are first found in the

Back 91

medial geniculate complex.

Front 92

In order to increase the decibel measurement of a sound, one would have to alter its wave

Back 92

amplitude

Front 93

The auditory hair-cell bodies are embedded in the

Back 93

basilar membrane

Front 94

what are some true statements about the audible spectrum

Back 94

. Children can often hear frequencies that adults cannot.
b. Small animals are often more sensitive to higher frequencies than larger animals are.
c. Animals that echolocate often rely on very high-frequency sounds
Collectively, mammals can hear tones at frequencies ranging from 20 Hz to 200 kHz.

Front 95

In which ways is the mechanism of hair-cell transduction distinct from other sensory transduction mechanisms (i.e., different from nonmechanical sensory systems)?

Back 95

Potassium influx from the endolymph depolarizes the hair cell.
b. Potassium efflux into the perilymph repolarizes the hair cell.
c. Calcium and calcium-activated potassium channels contribute to electromechanical resonance.
d. The two domains of the hair cell operate, in effect, as two distinct Nernstian compartments.

Front 96

Although the salience of the computations performed in auditory cortex is poorly understood, the current best guess as to its most important role is in

Back 96

conspecific communications and temporal sequencing of sounds

Front 97

Which of the following gives rise to tonotopy along the cochlea?

Back 97

The changing width and stiffness of the basilar membrane

Front 98

Which of the following statements about sensory transduction by hair cells is false?

Back 98

Bending of the cilia toward the longest cilium produces depolarization.

c. The dynamic range of the hair cell for reporting mechanical events is determined by the degree to which mechanical deflection can result in changes in membrane potential.
d. Hair cells are presynaptic to second-order sensory neurons.
e. The firing of action potentials in second-order sensory neurons can be either up- or down-regulated, depending on the direction in which the bundle of cilia (of the afferent hair cell) is bent.

Front 99

Which of the following is a major distinction between hair cells that operate at 500 Hz and those that operate at 5000 Hz?

Back 99

d. The 500 Hz cells fatigue far more readily than the 5000 Hz cells do.

Front 100

Which of the following is the most important problem that is solved by the generation of bilateral representations of auditory stimuli

Back 100

Sound localization

Front 101

what are some functions of cochlear implants (CIs)

Back 101

CIs require an electrical connection from an implanted stimulator to a cochlear electrode array.
c. CIs provide tonotopic delivery of electrical signals along the length of the cochlea.
d. CIs require an auditory signal processing device that decomposes sounds into component frequencies.
e. CIs electrically stimulate residual hair cells and/or primary auditory afferents.

Front 102

what are the primary function of the three bones in the middle ear what are the names?

Back 102

the malleus incus and stapes Amplification of sound pressure waves to increase auditory sensitivity

Front 103

Frequency refers to _____
amplitude refers to _______

Back 103

pitch, loudness

Front 104

the base of the basilar membrane is tuned for what type of frequenices ? apex?

Back 104

high, low

Front 105

receptor potentials are evoked by

Back 105

mechanically gated ion channels within the sterocilia

Front 106

what is the most direct pathway for the transmission of visual information from the eye to the brain

Back 106

Photoreceptor → bipolar cell → ganglion cell → brain

Front 107

two main functions of the retinal pigment epithelium are _______ and _______.

Back 107

phagocytosis of shed outer segments; regeneration of the photoreceptor photopigments

Front 108

Which of the statements about center-surround receptive fields in the retina is true

Back 108

Cells that are inhibited by light in their center are excited by light in their surround.
b. Cells that are excited by light in their center are inhibited by light in their surround.
c. The surround portion of the receptive field is typically an annulus (or donut-shaped ring) that surrounds the circular center.
The best stimulus for an on-center cell is light in its center and darkness in its surround.

Front 109

The main reason that rods are more sensitive to light than cones is that

Back 109

The rod transduction mechanism provides greater signal amplification.

Front 110

The primary or most proximate event that accounts for light-induced hyperpolarization of photoreceptors is

Back 110

a rapid fall in the concentration of cGMP, leading to closure of Na+/Ca2+ channels

Front 111

what is the mechanisms for rod signals conveyed in conditions of low light

Back 111

Rod bipolar cells synapse upon AII amacrine cells, which in turn synapse on ganglion cells

Front 112

bipolar cells

Back 112

Off-bipolar cells hyperpolarize in response to light.
c. On-bipolar cells depolarize in response to light.
d. Glutamate causes off-bipolars to depolarize.
e. Glutamate causes on-bipolars to hyperpolarize.

Front 113

Which of the following statements would correctly describe an off-center ganglion cell sitting on or near an edge (dark on one side, light on the other)?

Back 113

The cell would respond most strongly to this stimulus with its off-center sitting on the dark side of the border and just barely touching the border

Front 114

The iris

Back 114

controls the amount of light getting into your eyes

Front 115

the fovea

Back 115

is responsible for sharp vision area consist of only cones

Front 116

phototransduction signaling cascade initiated by light falling on a rod

Back 116

Absorption of a photon of light by 11-cis retinal
Increased activity of PDE (phosphodiesterase)
d. Dissociation of the α subunit of transducin from the β and γ subunits
e. A conformational change in the rhodopsin protein

Front 117

in mammalsfor both eyes ganglion cells whose receptive field are in one half of the visual field project to the opposite cerebral hemishere which region does this occur

Back 117

optic chiasm

Front 118

the temporal retina projects where

Back 118

ipsilateral same side

Front 119

the nasal retina projects where

Back 119

projects contralateral

Front 120

the LGN is

Back 120

a layered structure that recieve segregated input from the two eyes

Front 121

the top for parvocellular layers (6,5,4,3) recieve input from

Back 121

found dorsallyrecieve p input the ipsilateral and contralateral eye in the order of contra ipsi contra ipsi

Front 122

the bottom two magnocellular layers 2 and 1 recieve input from

Back 122

found more ventrally ipsi contra

Front 123

what does term functional architecture of the visual cortex mean

Back 123

column of neurons if you advance an electrode in the cortex perpendicular to its surface all neurons encountered have similar response properties if tangental path through many columns the orientation pattern changes in a steady clockwise and counterclockwise progressio

Front 124

The center-surround receptive field of the retinal ganglion cell is thought to arise in largest part due to

Back 124

the effects of horizontal cells on bipolar cells.

Front 125

The fovea

Back 125

lies at the center of the macula lutea

Front 126

In relation to other retinal ganglion cells, the P ganglion cells have

Back 126

finer spacial resolution and better color sensitivity.

Front 127

Retinal axons project to the

Back 127

a. thalamus.
b. hypothalamus.
c. superior colliculus

Front 128

P and M pathways have different response properties

Back 128

1. P cell receptive fields are smaller than M cell repeptive fields at the same retinal position
2. M cell acons conduct impulses faster than p cell axons
3. the response of p cells to prolonged visual stimulus particularly a color stimulu can be very sustained where M cells tend to respond more transiently
4. most p cells are sensitive to the color of stimulus; M cells are not
5. M cells are much more sensitive than P cells to low contrast black and white stimuli

Front 129

in the parietal cortex

Back 129

neurons are selective for higher order motion cues

Front 130

Define the silent synapse hypothesis

Back 130

which predicts that some synapses only express NMDA receptors whereas others express both AMPA and NMDA recpetors synapses with only the NMDA receptors would be functionally silent at hyperpolarized membrane potentials and thus when transmitter is released they will not yield a response however LTP at such silent synapses could occur by the rapid expression of AMPA receptors a mechanism that would account for the apparent rate in failure

Front 131

define augmentation and post tectanic potentiation

Back 131

longer lasting forms of placiticity following repetitive or tetanic simulation of synapse with prolonged approx 200 ms to 5 sec trains of stimuli applied at high frequencies and they refer to enhancements in neurotranmitter release

Front 132

define habituation

Back 132

Habituation is an extremely simple form of learning, in which an animal, after a period of exposure to a stimulus, stops responding to a stimulus

Front 133

Define critical period

Back 133

it is the period during the development when the capacity for adjustment in response to experience is substantially greater than it is after the circuit has matured

Front 134

What are the four examples of circuits that have been relatively well studied with respect to their dependence on instruction by early experience for normal development

Back 134

1. song learning by birds--days involves two components song memorization and vocal learning begins 8 weeks and last about 2 weeks circuitry is in the forebrain
2. sound localization by owls-midbriain 6-8 wks
3. binocular representation in the visual cortex
4. temperament in rats

Front 135

During development where are the affarents for binocular inputs located

Back 135

afferents that provide from the left and right eye begin to cluster in seperate areas in layer4 of the visual cortex the early clustering of eye specific inputs from the lateral geniculate nucleus is driven by patterns of spontaneous neuronal activity soon after brith the periods open during which visual experiences influences the competition among LGN afferents in layer four as long as the eyes are cordinated and used equally the final state consisting of equally wide ocular columns are achieved if however vision is impaired in one eye due to monoocular eyelid closure in an experimental animal or cataract in humans the balance is disrupted the LGN afferents that convey input from layer four lose the ability to drive lAyer four neurons

Front 136

give an example of how changing experience in ones sensory modality causes changes in a second modality

Back 136

because complex behaviors depend on information that is processed through hierachies of circuits the first condition implies that sensitive periods for higher levels of sensory modality can not open up until the circuits at lower levels open up pathways like human language or object recognition are examples of that

Front 137

what is neural plasiticity

Back 137

the ability of experience to modify neural circuity and thereby modify future thought behavior and feeling

Front 138

describe the properties of phasic (rapid adapting) versus tonic(slow adpating) receptors

Back 138

phasic receptors are usually "off" and turned on by a change in stimulus level (thermoceptors, pacinian corpucle) tonic receptors are usually turned on and do not exhibit