Visual System

Pregunta 1 de 57

1

The primary visual pathway

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eye

optic nerve

optic chiasm

optic tract

lateral geniculate nucleus (LGN)

optic radiation

primary visual cortex (V1)

Explicación

Pregunta 2 de 57

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In the optic chiasm fibers from the temporal hemiretinas ❌ and fibers from the nasal hemiretinas ❌.

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proceed to the ipsilateral hemisphere

cross to the contralateral hemisphere

Explicación

Pregunta 3 de 57

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Visible spetrum:

Wavelengths from to nm.

Explicación

Pregunta 4 de 57

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The optic disc is ( nasal, temporal ) to the fovea, so signals from the fovea are processed in the ( ipsilateral, contralateral ) hemisphere of V1.

Explicación

Pregunta 5 de 57

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Temporal to the binocular zone are the .

Explicación

Pregunta 6 de 57

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From V1 a ventral pathway goes to the ( temporal, parietal, occipital, frontal ) lobe with information about ( what, where, how big ) the stimulus is and its ( color, motion, shape, speed ).

A dorsal pathway goes to the ( parietal, occipital, frontal, temporal ) lobe with information about ( where, what ) the stimulus is and its ( motion, color, shape ).

Explicación

Pregunta 7 de 57

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Visuotopic maps are more precisly organized at ( early, higher ) levels of the pathway.

Explicación

Pregunta 8 de 57

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Retinal ganglion encode information about ( contrast, brightness, color, movement ) in the visual field.

Explicación

Pregunta 9 de 57

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Light is refracted by the and the and focused onto the .

(Alphabetical order)

Explicación

Pregunta 10 de 57

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In most vertebrates the ( cornea, lens ) is fixed and dynamic focusing is achieved by a flexible ( lens, cornea ) and the ( ciliary, flexing, extending ) muscle.

Explicación

Pregunta 11 de 57

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The fovea is free of blood-vessels.

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VERDADERO
FALSO

Explicación

Pregunta 12 de 57

1

In the foveola the proximal neurons of the retina are shifted aside so light has direct access to the photoreceptors.

Selecciona uno de los siguientes:

VERDADERO
FALSO

Explicación

Pregunta 13 de 57

1

The mammalian retina.

Put layers left and cell types right

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Outer nuclear layer

Outer plexiform layer

Inner nuclear layer

Inner plexiform layer

Ganglion cell layer

Photoreceptor cell bodies

Bipolar, horizontal and amacrine cells

Retinal ganglion cells

Explicación

Pregunta 14 de 57

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The vertical pathway down the retina is ( excitatory and inhibitory, excitatory, inhibitory ) and goes from the ( photoreceptors, retinal ganglion cells ) via ( bipolar cells, horizontal cells, amacrine cells ) to the ( retinal ganglion cells, photoreceptors ).

Horizontal pathways ( can be excitatory or inhibitory, are excitatory, are inhibitory ) and include ( horizontal cells, retinal ganglion cells, bipolar cells ) and ( amacrine cells, photoreceptor cells ).

Explicación

Pregunta 15 de 57

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Retinal Pigmental ( Epithelium, Epiderm, Epimeninges ) (RPE) is located between the light-sensitive outer segments of the ( photoreceptors, bipolar cells, retinal ganglion cells ) and the blood vessels of the ( choroid, cornea ).

Explicación

Pregunta 16 de 57

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Bruch's membrane is the ( innermost, outermost ) layer of the choroid and acts as a ( diffusion barrier, light absorbing barrier ) between ( Retinal Pigmental Epithelium (RPE), the photoreceptors ) and the ( blood vessels, bipolar cells ).

Explicación

Pregunta 17 de 57

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There are approximately ( 100 million, 100 billion, 10 million ) rods and ( 6 million, 60 million, 20 million ) cones.
There is only 1 type of ( rods, cones ) but 3 types of ( cones, rods ).

The fovea contains no ( rods, cones ) but is densely packed with small ( cones, rods ).

A few millimeters outside the fovea ( rods greatly outnumber cones, cones greatly outnumber rods ).

Explicación

Pregunta 18 de 57

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vision: vision under low-light levels.

vision: vision under intermediate lighting conditions.

vision: vision under well-lit conditions.

Explicación

Pregunta 19 de 57

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Rods are responsible for ❌ vision.

Cones are responsible for ❌ vision.

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scotopic and mesopic

scotopic

mesopic and photopic

photopic

Explicación

Pregunta 20 de 57

1

Which one is true?

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Cones are much faster than rods.
Rods are much faster than cones.
Cones and rods have approximately the same speed.

Explicación

Pregunta 21 de 57

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The central part of the fovea is called foveola or foveal .
The adjacent region is called foveal .

Explicación

Pregunta 22 de 57

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The fovea contains mostly ❌ and ❌cones but only very few ❌cones.

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M-

L-

S-

Explicación

Pregunta 23 de 57

1

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Receptive field of a visual neuron:

The area ( in visual space, on the retina ) where changes in light intensity (or composition, layout, ...) trigger a change in the neuronal response. This change can be excitatory or/and inhibitory.

Explicación

Pregunta 24 de 57

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The mitochondria of photoreceptors are contained in their ( inner segment, outer segment, cell body, synaptic terminal ).

Explicación

Pregunta 25 de 57

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Outer and inner segments of rods and cones are connected by the (cc).

Explicación

Pregunta 26 de 57

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Absorption of a photon ( hyperpolarizes, depolarizes ) photoreceptors and generates ( OFF, ON )-responses.

Explicación

Pregunta 27 de 57

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Phototransduction

Rhodopsin is densely packed in the ( disk membranes, inner segment ) of rods. It consists of the protein opsin and the light-absorbing part ( retinal, retinol, metarhodopsin ).
In the dark retinal is in the ( 11-cis, all-trans ) configuration but absorption of a photon causes a flip to the ( all-trans, 11-cis ) configuration.
This causes a change in the opsin to an ( activated, inactivated ) state called ( metarhodopsin II, metarhodopsin, rhodopsin II ).

Metarhodopsin II can then activate ( hundreds of molecules, exactly one molecule ) called transducin. Transducin in turn ( activates, deactivates ) phosphodiesterase which hydrolizes cGMP and leads to ( a decrease, an increase ) of the cGMP level.
PDE hydrolizes ( more than 1000 cGMP, approximately 1 cGMP ) per second.

This causes the Na+ and Ca2+ channels to ( close, open ) and a sharp ( decrease, increase ) in glutamate release.

The metarhodopsin II splits within minutes to opsin and free ( all-trans retinal, 11-cis retinal ). This is either directly transformed back to 11-cis retinal of first reduced to all-trans-retinol, then to 11-cis retinol and then back to 11-cis retinal.
This happens in ( the retinal pigment epithelium, the outer plexiform layer, the inner plexiform layer, Bruch's membrane, the outer nuclear layer, the inner nuclear layer ).

Explicación

Pregunta 28 de 57

1

Metarhodopsin II can activate hundreds of transducin molecules because

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there is a lot more metarhodopsin II than transducin.
both are anchored to the membrane of the photoreceptor.

Explicación

Pregunta 29 de 57

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Termination of the phototransduction cascade

(1) Metarhodopsin is first phosphorylated and its interaction with ( transducin, phosphodiesterase, cGMP ) is blocked by the protein ( arrestin, cGMP ).

(2) Active transducin has ( GTPase, GDPase, cGMPase ) activity which leads to ( inactivation, reactivation ) of ( phosphodiesterase, cGMP ).

(3) A negative feedback by ( decrease, increase ) of ( Ca2+, Na+ ) influx leads to synthesis of new ( cGMP, GTP, GDP, GMP ).

Explicación

Pregunta 30 de 57

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cGMP synthesis is 5-10 times higher in ❌ than in ❌.

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cones

rods

Explicación

Pregunta 31 de 57

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Adaptation to light is modulated by changes in the influx of ( Ca2+, Na+ ).

Explicación

Pregunta 32 de 57

1

Photoreceptors tonically fire action potentials and shut down as a reaction to a light stimulus.

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Explicación

Pregunta 33 de 57

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Photoreceptors transmit their signals to bipolar and horizontal cells via synapses.

Their function is not entirely clear but they serve as a hotspot of synaptic vesicle exocytosis as well as a replenishment station.
They disassemble when there is a high concentration of .

Explicación

Pregunta 34 de 57

1

Which one is true?

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Ribbon synapses look the same in rods and cones.
Ribbon synapses differ between rods and cones.

Explicación

Pregunta 35 de 57

1

Horizontal cells form synapses to ❌ in the ❌, while amacrine cells form synapses to ❌ in the ❌.

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photoreceptors

outer plexiform layer

retinal ganglion cells

bipolar cells

inner plexiform layer

outer nuclear layer

inner nuclear layer

ganglion cell layer

Explicación

Pregunta 36 de 57

1

The synapses of cones connect ❌ bipolar and horizontal cells and form ❌.

The synapses of rods connect ❌ bipolar and horizontal cells and form ❌.

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to ON and OFF

only to ON

only to OFF

multiple small ribbons

a single large ribbon

Explicación

Pregunta 37 de 57

1

Which of these cells fire action potentials?

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Photoreceptors
Horizontal cells
Bipolar cells
Retinal ganglion cells

Explicación

Pregunta 38 de 57

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ON- and OFF-type responses occur for the first time in ( bipolar cells, photoreceptors, retinal ganglion cells ). The lateral inhibition is mediated by ( inhibitory, excitatory ) ( horizontal cells, amacrine cells ) which use ( electrical, chemical ) synapses.

Explicación

Pregunta 39 de 57

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Rod ON and cone ON bipolar cells express ❌ which leads to ❌ glutamate receptors.

Cone OFF bipolar cells express ❌ which leads to ❌ glutamate receptors.

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mGluR6

cGMP

PDE

inhibitory

AMPA-/kainate

excitatory

Explicación

Pregunta 40 de 57

1

Horizontal cells provide negative feedback to cone terminal which leads to a short peak in the cone response and a subsequent smaller steady level.
This is related to the transient response of retinal ganglion ells.

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VERDADERO
FALSO

Explicación

Pregunta 41 de 57

1

There are ON and OFF ❌ bipolar cells but only ❌ ❌ bipolar cells.

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cone

rod

ON

OFF

Explicación

Pregunta 42 de 57

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Rod ON bipolar cells connect to ( AII amacrine cells, horizontal cells, retinal ganglion cells ) which make ( excitatory, inhibitory ) ( gap junctions, glutamatergic synapses ) to ON-cone bipolar cells and ( glycinergic, glutamatergic, GABAergic ) ( inhibitory, excitatory ) synapses to OFF-cone bipolar cells.

Explicación

Pregunta 43 de 57

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Responses of retinal ganglion cells ...

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are independent of absolute brightness and encode relative light intensities of center vs. surround.
encode the absolute brightness and differentiation between relative light intensities happens further down the pathway in the visual cortex.

Explicación

Pregunta 44 de 57

1

?

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lens

pupil

posterior eyechamber

anterior eyechamber

cornea

iris

sciliary muscle

sclera

choroid

macula

fovea

retina

Explicación

Pregunta 45 de 57

1

Alphabetic:

Low-level processing:
❌
❌
❌
❌

Intermediate-level processing:
❌
❌
❌
❌

High-level processing:
❌

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Color

Contrast

Movement direction

Orientation

Contour integration

Object motion and shape

Surface depth

Surface properties

Object identification

Explicación

Pregunta 46 de 57

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Development of the eye:

The and the derm form the eye.
The inverted optic cup forms the , the outer layer the .
The retina is a protrusion of the .

Explicación

Pregunta 47 de 57

1

For near vision the lens is ❌ and the ciliary muscle ❌, for far vision the lens is ❌ and the ciliary muscle ❌.

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round

flat

contracted

relaxed

Explicación

Pregunta 48 de 57

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Shortsightedness:
Farsightedness:

Explicación

Pregunta 49 de 57

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Diffusion barriers of the mammalian retina

Explicación

Pregunta 50 de 57

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Cortical magnification:

The central degrees of the retina project to % of the primary visual cortex.

Explicación

Pregunta 51 de 57

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Termination of the phototransduction cascade:

Rhodopsin-kinase ( phosphorylates, hydrolates ) metarhodopsin, which then binds arrestin that blocks the interaction with ( transducin, phosphodiesterase, cGMP ) (( GDP-GTP, GMP-GDP ) exchange).

Active transducin has an intrinsic ( GTP, GDP, GMP )-ase activity that splits its own GTP to GDP and thereby inactivates ( phosphodiesterase, cGMP ).

The ( decrease, increase ) in ( Ca2+, Na+, K+ ) leads to the activation of Guanylate-cyclase by ( GCAP, GCAT, GBAP, GBBT ). This leads to the synthetization of cGMP from ( GTP, GDP, 5'GMP ).

Explicación

Pregunta 52 de 57

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( Horizontal, Amacrine, Photoreceptor, Retinal ganglion ) cells are responsible for the OFF-surround response of bipolar cells.

Explicación

Pregunta 53 de 57

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Cone-OFF bipolar cells and horizontal cells are excited by glutamate via glutamate receptors.

Explicación

Pregunta 54 de 57

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Three proposed mechanisms for negative feedback from horizontal cells to photoreceptor cells:

(a) ( GABA, glycine, acetylcholine ) release
(b) Ephaptic modulation by hemi-gap junctions in horizontal cell ( dendrites, axons )
(c) ( H+, Phosphor units, NO ) modulates presynaptic photoreceptor ( calcium, sodium, potassium ) currents

Explicación

Pregunta 55 de 57

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OFF retinal ganglion cells have their synapses ( above, below ) ON retinal ganglion cells in the ( inner plexiform layer, outer plexiform layer, inner nuclear layer, outer nuclear layer, ganglion cell layer ).

Explicación

Pregunta 56 de 57

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P retinal ganglion cells have ❌ receptive fields with ❌ and project to the ❌.

M retinal ganglion cells have ❌ receptive fields with ❌ and project to the ❌.

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small

high spectral sensitivity

ventral stream

large

broad spectral sensitivity

dorsal stream

Explicación

Pregunta 57 de 57

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Metarhodopsin II consists of ( all-trans, 11-cis ) ( retinal, retinol ) bound to opsin. It helps to exchange ( GDP to GTP, GMP to GDP, GTP to cGMP ) on hunderds of transducin molecules to activate them (first amplification step).

Phosphodiesterase has an ( inhibitor, activator ) which is ( removed, produced ) by active transducin.

The ( alpha, beta, gamma, beta-gamma )-subunit of active PDE hydrolyzes more than thousand ( cGMP to 5'GMP, cGMP to GDP, GDP to GTP, GTP to cGMP ) per second (second amplification step).

	Creado por Lukas Paulun hace más de 5 años

Master (From Membrane to Brain [Lecture]) Neuroscience Test sobre Visual System, creado por Lukas Paulun el 08/12/2018.

Visual System

Pregunta 1 de 57

The primary visual pathway

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Explicación

Pregunta 2 de 57

In the optic chiasm fibers from the temporal hemiretinas ❌ and fibers from the nasal hemiretinas ❌.

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Explicación

Pregunta 3 de 57

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Visible spetrum: Wavelengths from to nm.

Explicación

Pregunta 4 de 57

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The optic disc is nasal temporal( nasal, temporal ) to the fovea, so signals from the fovea are processed in the ipsilateral contralateral( ipsilateral, contralateral ) hemisphere of V1.

Explicación

Pregunta 5 de 57

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Temporal to the binocular zone are the .

Explicación

Pregunta 6 de 57

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Explicación

Pregunta 7 de 57

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Visuotopic maps are more precisly organized at early higher( early, higher ) levels of the pathway.

Explicación

Pregunta 8 de 57

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Retinal ganglion encode information about contrast brightness color movement( contrast, brightness, color, movement ) in the visual field.

Explicación

Pregunta 9 de 57

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Light is refracted by the and the and focused onto the . (Alphabetical order)

Explicación

Pregunta 10 de 57

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In most vertebrates the cornea lens( cornea, lens ) is fixed and dynamic focusing is achieved by a flexible lens cornea( lens, cornea ) and the ciliary flexing extending( ciliary, flexing, extending ) muscle.

Explicación

Pregunta 11 de 57

The fovea is free of blood-vessels.

Selecciona uno de los siguientes:

Explicación

Pregunta 12 de 57

In the foveola the proximal neurons of the retina are shifted aside so light has direct access to the photoreceptors.

Selecciona uno de los siguientes:

Explicación

Pregunta 13 de 57

The mammalian retina. Put layers left and cell types right

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Explicación

Pregunta 14 de 57

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Explicación

Pregunta 15 de 57

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Explicación

Pregunta 16 de 57

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Explicación

Pregunta 17 de 57

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Explicación

Pregunta 18 de 57

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vision: vision under low-light levels. vision: vision under intermediate lighting conditions. vision: vision under well-lit conditions.

Explicación

Pregunta 19 de 57

Rods are responsible for ❌ vision. Cones are responsible for ❌ vision.

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Explicación

Pregunta 20 de 57

Which one is true?

Selecciona una de las siguientes respuestas posibles:

Explicación

Pregunta 21 de 57

Rellena los espacios en blanco para completar el texto.

The central part of the fovea is called foveola or foveal . The adjacent region is called foveal .

Visible spetrum:

Wavelengths from to nm.

The optic disc is ( nasal, temporal ) to the fovea, so signals from the fovea are processed in the ( ipsilateral, contralateral ) hemisphere of V1.

Visuotopic maps are more precisly organized at ( early, higher ) levels of the pathway.

Retinal ganglion encode information about ( contrast, brightness, color, movement ) in the visual field.

Light is refracted by the and the and focused onto the .

(Alphabetical order)

In most vertebrates the ( cornea, lens ) is fixed and dynamic focusing is achieved by a flexible ( lens, cornea ) and the ( ciliary, flexing, extending ) muscle.

The mammalian retina.

Put layers left and cell types right

vision: vision under low-light levels.

vision: vision under intermediate lighting conditions.

vision: vision under well-lit conditions.

Rods are responsible for ❌ vision.

Cones are responsible for ❌ vision.

The central part of the fovea is called foveola or foveal .
The adjacent region is called foveal .

Receptive field of a visual neuron:

The area ( in visual space, on the retina ) where changes in light intensity (or composition, layout, ...) trigger a change in the neuronal response. This change can be excitatory or/and inhibitory.

The mitochondria of photoreceptors are contained in their ( inner segment, outer segment, cell body, synaptic terminal ).

Absorption of a photon ( hyperpolarizes, depolarizes ) photoreceptors and generates ( OFF, ON )-responses.

Adaptation to light is modulated by changes in the influx of ( Ca2+, Na+ ).

Photoreceptors transmit their signals to bipolar and horizontal cells via synapses.

Their function is not entirely clear but they serve as a hotspot of synaptic vesicle exocytosis as well as a replenishment station.
They disassemble when there is a high concentration of .

The synapses of cones connect ❌ bipolar and horizontal cells and form ❌.

The synapses of rods connect ❌ bipolar and horizontal cells and form ❌.