Sensory Systems Flashcards
Light enters the human eye through an opening in the iris called the
Select one:
a. retina
b. pupil
c. cornea
d. fovea
b. pupil
In humans, all of the visual receptors are in the
Select one:
a. last layer of the retina to be reached by light entering the eye
b. middle neural layer of the retina
c. first layer of the retina to be reached by light entering the eye
d. cornea
a. last layer of the retina to be reached by light entering the eye
In comparison to the photopic system, the scotopic system has more
Select one:
a. rods
b. receptors in the periphery of the retina
c. sensitivity in dim illumination
d. all of the above
d. all of the above
The brightness of a light depends on its
Select one:
a. intensity
b. wavelength
c. colour
d. both A and B
d. both A and B
The retina-geniculate-striate system is organized
Select one:
a. from top to bottom
b. from left to right
c. on the basis of wavelength
d. retinotopically
d. retinotopically
The receptive field of a visual neuron is the area of the
Select one:
a. striate cortex within which stimulation can activate the neuron
b. retina within which stimulation with diffuse light can activate the neuron
c. striate cortex within which stimulation can inhibit the neuron
d. visual field within which the suitable visual stimulus can influence the firing of the neuron
d. visual field within which the suitable visual stimulus can influence the firing of the neuron
Posterior parietal cortex is considered to be association cortex because it receives substantial sensory input from the
Select one:
a. hypothalamus
b. secondary areas of more than one sensory system
c. thalamus
d. primary visual cortex
b. secondary areas of more than one sensory system
Connections between various areas of visual cortex are virtually always
Select one:
a. excitatory
b. unidirectional
c. reciprocal
d. inhibitory
c. reciprocal
A major principle of sensory system organisation is
Select one:
a. hierarchical organization
b. functional segregation
c. parallel processing
d. all of the above
d. all of the above
The auditory system is organised
Select one:
a. retinotopically
b. tonotopically
c. somatotopically
d. geographically
b. tonotopically
What are the amacrine and horizontal cells specialised for?
Lateral communication
Do rod-fed circuits have a high or low convergence?
High; Lots of rod cells to one retinal ganglion cell
The _______ are donut-shaped bands of contractile tissue that regulates the amount of light that reaches the retina
Irises
Prey animals have _______ eyes, which allow them to see the predators approaching from most directions due to a larger field of vision
Side-facing
_______ is the difference in the position of the same image on two retinas
Binocular disparity
Amacrine cells and horizontal cells are responsible for _________ communication
Lateral
______ is the process of perceiving large surfaces by extracting information about the edges and making inferences about the shape from it
Surface interpolation
In scotopic vision, hundreds of _________ converge on a single retinal ganglion cell
Rods
The majority of the visual neurons respond only to _______ images
Changing
Rhodopsin is a _______ receptor that does not respond to neurotransmitter molecules
G-protein-coupled
The path that all the signals take to reach the right primary visual cortex from the left visual field is either _________ or contralateral
Ipsilateral
What are Mach band and what do they demostrate?
Mach bands are a series of homogeneous stripes of different intensity. They demostrate an illusion where adjacent to each edge, the brighter stripe looks brighter than it really is and the darker stripe looks darker than it really is
The area of the visual field within which it is possible for a visual stimulus to influence the firing of that neuron is called what?
Receptive field
What is the absorption spectrum?
a graph of the ability of a substance to absorb light of different wavelengths
What is accommodation?
the process of adjusting the configuration of the lenses to bring images into focus on the retina
What is acuity?
the ability to see the details of objects
What is agnosia?
a failure of recognition of sensory stimuli that is not attributable to a sensory or to verbal or intellectual impairment
What is akinetopsia?
a deficiency in the ability to see movement progress in a smooth fashion, which often results from damage to the MT area
What are amacrine cells?
retinal neurons that are specialised for lateral communication
What is an association cortex?
an area of the cortex that receives input from more than one sensory system
What is the auditory nerve?
the branch of the cranial nerve VIII that carries auditory signals from the hair cells in the basilar membrane
What is the basilar membrane?
the membrane of the organ of Corti in which the hair cell receptors are embedded
What does binocular mean?
cells in the visual system that are binocular respond to stimulation of either eye
What is binocular disparity?
the difference in position of the same image on the two retinas
What are bipolar cells?
bipolar neurons that form the middle layer of the retina
What is the blind spot?
the area on the retina where the bundle of axons from the retinal ganglion cells leave the eye as the optic nerve
What is blindsight?
the ability to respond to visual stimuli in a scotoma without conscious awareness of those stimuli
What are blobs?
peglike, cytochrome oxidase-rich, dual-opponent colour columns
What are ciliary muscles?
the eye muscles that control the shape of the lenses
What is the cochlea?
the long, coiled tube in the inner ear that is filled with fluid and contains the organ of Corti and its auditory receptors
What is colour constancy?
the tendency of an object to appear the same colour even when the wavelengths of light that is reflects chance
What is the “control of behaviour” versus “consciour perception” theory?
the theory that the dorsal stream mediates behavioural interactions with objects and the ventral stream mediates the conscious perception of objects
What are complementary colours?
pairs of colours that produces white or grey when combined in equal measure
What is completion?
the visual system’s automatic use of information obtained from receptors around the blind spot, or scotoma, to create a perception of the missing portion of the retinal image
What are complex cells?
neurons in the visual cortex that respond optimally to straight-edge stimuli in a certain orientation in any part of their receptive field
What is component theory?
the theory that the relative amount of activity produced in three different classes of cones by light determines its perceived colour (also called trichromatic theory)
What are cones?
the visual receptors in the retina that mediate high acuity colour vision in good lighting
What is conscious awareness?
the awareness of one’s perceptions; typically inferred from the ability to verbally describe them
What is contrast enhancement?
the intensification of the perception of edges
What is cytochrome oxidase?
an enzyme present in particularly high concentrations in the mitochondria of dual-opponent colour cells of the visual cortex
What is the dorsal stream?
the group of visual pathways that flows from the primary visual cortex to the dorsal prestriate cortex to the posterior parietal cortex
What are dual-opponent colour cells?
neurons that respond to the differences in the wavelengths of light stimulating adjacent areas of their receptive field
What is duplexity theory?
the theory that cones and rods mediate photopic and scotopic vision, respectively
What are fixational eye movements?
involuntary movements of the eyes (tremor, drifts, and saccades) that occur when a person tries to fix their gaze of a point
What is fourier analysis?
a mathematical procedure for breaking down a complex wave form into component sine waves of various frequencies
What is the fovea?
the central indentation of the retina, which is specialised for high-acuity vision
What is functional segregation?
organisation into different areas, each of which performs a different function; for example, in sensory systems, different areas of secondary and association cortex analyse different aspects of the same sensory stimulus
What is the fusiform face area?
an area of human cortex, located at the boundary between the occipital and temporal lobes, that is selectively activated by human faces
What are hair cells?
the receptors of the auditory system
What does hemianopsic?
having a scotoma that covers half of the visual field
What is hierarchical organisation?
organisation into a series of levels that can be ranked with respect to one another; for example, in sensory systems, primary cortex, secondary cortex, and association cortex perform progressively more detailed analyses
What are horizontal cells?
retinal neurons whose specialised function is lateral communication
What is the inferior colliculi?
the structures of the tectum that receive auditory input form the superior olives
What is the inferotemporal cortex?
the cortex of the inferior temporal lobe, in which is located an area of secondary visual cortex
What is the lateral geniculate nuclei?
the six-layered thalamic structures that receive input from the retinas and transmit their output to the primary visual cortex
What is lateral inhibition?
inhibition of adjacent neurons or receptors in a topographical array
What are magnocellular layers?
the layer of the lateral geniculate nuclei that are composed of neurons with large cell bodies; the bottom two layers (also called M layers)
What is the medial geniculate nuclei?
the auditory thalamic nuclei that receive input from the inferior colliculi and project to primary auditory cortex
What does monocular mean?
involving only one eye
What is the MT area?
an area of cortex, located near the junction of the temporal, parietal, and occipital lobes, whose function appears to be the perception of motion
What are off-centre cells?
visual neurons that respond to lights shone in the centre of their receptive fields with “off” firing and to lights shone in the periphery of their receptive fields with “on” firing
What are on-centre cells?
visual neurons that respond to lights shone in the centre of their receptive fields with “on” firing and to lights shone in the periphery of their receptive fields with “off” firing
What is opponent-process theory?
the theory that a visual receptor or a neuron signals one colour when it responds in one way (e.g., by increasing its firing rate) and signals the complementary colour when it responds the opposite way (e.g., by decreasing its firing rate)
What is the organ of Corti?
the auditory receptor organ, comprising the basilar membrane, the hair cells, and the tectorial membrane
What are ossicles?
the three small bones of the middle ear: the malleus, the incus, and the stapes
What is the oval window?
the membrane that transfers vibrations form the ossicles to the fluid of the cochlea
What is parallel processing?
the simultaneous analysis of a signal in different ways by the multiple parallel pathways of a neural network
What are the parvocellular layers?
the layers of the lateral geniculate nuclei that are composed of neuron with small cell bodies; the top four layers (also called P layers)
What is perception?
the higher-order process of integrating, recognising, and interpreting complete patterns of sensations
What is a perimetry test?
the procedure used to map scotomas
What is the photopic spectral sensitivity curve?
the graph of the sensitivity of cone-mediated vision to different wavelengths of light
What is photopic vision?
cone-mediated vision, which predominates when lighting is good
What is the posterior parietal cortex?
an area of association cortex that receives input from the visual, auditory, and somatosensory systems and is involved in the perception of spatial location and guidance of voluntary behaviour
What is the prestriate cortex?
the band of tissue in the occipital lobe that surrounds the primary visual cortex and contains areas of secondary visual cortex
What is the primary sensory cortex?
an area of sensory cortex that receives most of its input directly from the thalamic relay nuclei of one sensory system
What is the primary visual cortex?
the area of the cortex that receives direct input from the lateral geniculate nuclei (also called striate cortex)
What is prosopagnosia?
visual agnosia for faces
What is the Purkinje effect?
in intense light, red and yellow wavelengths looks brighter than blue or green wavelengths of equal intensity; in dim light, blue and green wavelengths look brighter than red and yellow wavelengths of equal intensity
What is a receptive field?
the area of the visual field within which it is possible for the appropriate stimulus to influence the firing of a visual neuron
What are receptors?
cells that are specialised to receive chemical, mechanical, or radiant signals from the environment
What are retinal ganglion cells?
retinal neurons whose axons leave the eyeball and form the optic nerve
What is the retinal-geniculate striate pathways?
the major visual pathway from each retina to the striate (primary visual) cortex via the lateral geniculate nuclei of the thalamus
What is retinex theory?
Land’s theory that the colour of an object is determined by its reflectance, which the visual system calculates by comparing the ability of adjacent surfaces to reflect short, medium, and long wavelengths
What does retinotopic mean?
organised, like the primary visual cortex, according to a map of the retina
What is rhodopsin?
a photopigment of rods
What are rods?
the visual receptors in the retina that mediate achromatic, low-acuity vision under dim light
What are saccades?
the rapid movements of the eyes between fixations
What is a scotoma?
an area of blindness produced by damage to, or disruption of, an area of the visual system
What is a scotopic spectral sensitivity curve?
the graph of the sensitivity of rod-mediated vision to different wavelengths of light
What is scotopic vision?
rod-mediated vision, which predominates in dim light
What is a secondary sensory cortex?
an area of the cerebral cortex that receives most of its input from the primary sensory cortex of one sensory system or from other areas of secondary cortex of the same system
What is the secondary visual cortex?
areas of cerebral cortex that receive most of their input from the primary visual cortex
What are the semicircular canals?
the receptive organs of the vestibular system
What is sensation?
the process of detecting the presence of stimuli
What is sensitivity?
in vision, the ability to detect the presence of dimly lit objects
What are simple cells?
neurons in the visual cortex that respond maximally to straight-edge stimuli of a particular width and orientation
What are the superior olives?
medullary nuclei that play a role in sound localisation
What is surface interpolation?
the process by which we perceive surfaces; the visual system extracts information about edges and from it infers the appearance of large surfaces
What is the tectorial membrane?
the cochlear membrane that rests on the hair cells
What is tinnitus?
ringing in the ears
What does tonotopic mean?
organised, like the primary auditory cortex, according to the frequency of sound
What is transduction?
the conversion of one form of energy to another
What is the tympanic membrane?
the eardrum
What is the ventral stream?
the group of visual pathways that flows from the primary visual cortex to the ventral prestriate cortex to the inferotemporal cortex
What is the vestibular system?
the sensory system that detects changes in the direction and intensity of head movements and that contributes to the maintenance of balance through its output to the motor system
What is visual agnosia?
a failure to recognise visual stimuli that is not attributable to sensory, verbal, or intellectual impairment
What is the visual association cortex?
areas of cerebral cortex that receive input from areas of secondary visual cortex as well as from secondary areas of other sensory systems
What is the “where” versus “what” theory?
the theory that the dorsal stream mediates the perception of where things are and the ventral stream mediates the perception of what thing are
