Sensory Systems - glossary terms Flashcards
action
motor activities such as moving the head or eyes, and locomoting through the environment
action is one of the major outcomes of the perceptual process
action potential
rapid increase in positive charge in nerve fibre (axon) that travels down the fibre. also called nerve impulse or spike
afferent neurones
neurons that carry action potentials from receptors in the sensory organs towards the central nervous system
auditory perception
the sense of hearing, one of the five traditional senses
bottom-up processing
processing that is based on stimulation of the receptors. also called data-based processing. opposite of top-down
central nervous system
the brain and the spinal chord
efferent neurones
neurones that carry action potential away from the central nervous system to effectros such as muscles
environmental stimulus
the stimulus “out there” in the external environment
dualism
a major philosophical approach stating that the mind has an existence separate from the material world of the body. dualists argue that mind and brain are two separate phenomena
gustatory perception
the sense of tasting, one of the five traditional sense
homunculus
a map-like representation of regions of the body in the brain
materialism
a major philosophical approach stating that the only that exists is matter, and that all things, including the mind and consciousness, are the result of interaction between bits of matter. materialists argue that mind and brain are both physical mediums
neuron
one of two cell types in the nervous system (along with glial cells), neurons are responsible for processing sensory, motor, cognitive and affective information
olfactory perception
the sense of smelling, one of the five traditional sense
perception
the organization identification and interpretation of sensory information in order to represent, understand and interact with the environment
peripheral nervous system
the part of the nervous system apart from the brain and the spinal chord
primary receiving areas
areas of the cerebral cortex that are first to receive most of the signals initiated by a senses receptors
give an example of a primary receiving area
the occipital cortex is the site of the primary receiving area for vision, and the temporal lobe is the site of the primary receiving area for hearing
receptive field
a neuron’s receptive field is the area on the receptor surface that when stimulated affects the firing of the neuron
receptor
a sensory receptor is a cell sensitive to environmental energy
receptors change this energy into electrical signals in the nervous system
recognition
the ability to place an object in a category that gives it meaning
eg recognizing a particular red object as a tomato or giving a physical sound a semantic meaning
sensory organs
specialized organs that interact with environmental stimuli and that contain receptors that transduce a specific type of stimulus energy into nerve activity
sensory systems
the parts of the nervous system which are responsible for processing sensory information
tactile perception
the sense of touching
top-down processing
processing that starts with the analysis of high-level information such as knowledge a person brings to a situation. also called knowledge based processing
distinguish from bottom-up or data-processing which is based on incoming data
topographic maps
the ordered projection of a sensory surface or an effector system to one ot more structures of the central nervous sytem. topographic maps can be found in many motor systems
transducer
a device that converts a signal in one form of energy to another form of energy
transduction
in the sense, the conversion of environmental energy into electrical energy eg receptors in the eye transduce light energy into electrical energy
visual perception
the sense of seeing, one of the five traditional sense
anterior
toward the front end
opposite - posterior
autonomic nervous system
the part of the PNS that influences the function of internal organs. the ANS acts largely unconsciously and regulates the heart rate, digestion, respiratory rate, pupillary response, urination and sexual arousal
brainstem
the posterior part of the brain, adjoining and structurally continuous with the spinal chord. in humans, it is usually described as including the medulla oblongata, pons, and midbrain
brodmann area
a region of the berevral cortex that is defined by its cytoarchitecture, or histological structure and organization of cells
cerebellum
a large, highly convoluted (in-folded) structure located dorsal to the brainstem at the level of the pons, also know as little cerebrum
cerebral cortes
the layered sheet of neurons that covers the surface of the brain and contains the machinery for creating perception, as wekk as other funcitons, such as language, memory and thinking. it is divided in tow (lateral) hemispheres each containing four major lobes
contralateral
on the opposite side of the body
opposite - ipsilateral
coronal plane
a plane that shows brain structures as seen from the front
also called frontal plane
distal
located more distant from the point of origin or attatchment
opposite - proximal
dorsal
toward the back, away from the ventral (stomach) side. the top of the brain is considered dprsal because it has this position in four-legged animals
opposite of ventral
frontal lobe
one of the four major lobes of the cerebral cortex
gray matter
a major component of the central nervous system that contains primarily neuronal cell bodies
inferior
below another part
opposite - superior
ipsilateral
on the same side
later
toward the side, away from the midline
opposite - medial
medial
toward the midline, away from the side\
opposite - lateral
occipital lobe
one of the four major lobes of the cerebral cortex, which holds amongst others the primary visual cortex
parietal lobe
one of the four major lobes of the cerebral cortex, which holds amongst others the primary somasensory cortex
posterior
toward the rear end
opposite - anterior
proximal
located close to the point of origin or attatchment
opposite - distal
sagittal plane
a plane that shows brain structures as seen from the side
somatic nervous system
the part of the PNS that is associated with body movement through the control of skeletal (voluntary) muscles and with the reception of external stimuli
superior
above another part
opposite - inferior
temporal lobe
one of the four major lobes of the cerebral cortex which holds amongst others the primary auditory cortex
thalamus
a plane that shows brain structures as seen from above
also called the horizontal plane
ventral
toward the stomach, away from the dorsal (back) side
opposite of dorsal
white matter
a major component of the central nervous system that contains million myelinated axons (ie the wires between neuronal cell bodies)
action potential
rapid increase in positive charge in a nerve fibre (axon) that travels down the fibre. action potentials are all-or-nothing events (compared to graded potential)
also called nerve impulse or spike
axon
a long projection of a neuron that typically conducts action potentials away from the neuron’s cell body. also known as nerve fibre
cell
the basic structural, functional and biological unit of all known living organisms
cell body
the core region of a cell containing the nucleus and other cell organelles
dendrite
branching extensions of the neurons plasma membrane that increase the surface area of the neuron and collect neuronal activity from other cells
equilibrium potential
the membrane potential at which a particular type of ion has no driving force to diffuse through the plasma membrane in either direction. at the equilibrium potential, chemical and electrical gradients are equal in magnitude
glia cells
non-neuronal cells in the nervous system that provide support and protection for neurons. among many functions, glia cells are responsible for the myelination of axons
graded potential
a relatively small charge in membrane potential, for example by opening ligand-gated ion channels. the strength of a graded potential is given relative to the strength of stimulation (compare action potential)
ligand-gated channels
a group of ion channels, which open to allow ions such as Na, K, Ca and Cl to pass through the membrane in response to the binding of a messenger
membrane potential
the difference in electric potential between the interior and the exterior of a biological cell
myelin
a fatty substance te surrounds the axon of many neurons. myelin increases the membrane resitance helping to speed the conductance of action potentials
neuron doctrine
the concept proposing that the neuron is the fundamental unit of the nervous system. compare reticular theory
neurotransmitter
chemical messenger released by neurons onto a target cell with an excitatory or inhibitory effect
oligodendrocytes
a type of glia cells in the central nervous system. oligodendrocytes cells wrap around axons to form the myelin sheath - equivalent to Schwann cells
nucleus of a cell
a membrane-enclosed organelle found in eukaryotic cells that contain most of thecells genetic material
plasma membrane
a biological membrane that separates the interior of all cells from the outside environment. the plasma membrane is selsctively permeable to ions and organic molecules and controls the movement of substnces in and out of the cell
postsynaptic
referring to the neuron (or parts thereof) after the synapse with respect to the flow of information
compare to presynaotic
postsynaptic potential
changes int he membrane potential of the post synaptic neuron of a synapse, postsynaptic potentials are graded potentials that are either excitatory or inhibitory
potassium
the ion of the potassium atom. one of the main players contributing to the membrane potential of neurons
presynaptic
referring to the neuron (or parts thereof) before the synapse with respect to the flow of information
compare postsynaptic
resting potential
the membrane potential in the absence of stimulation. the resting potential of neurons is typically around -70mV. it depends on the equilibrium potentials of contributing ions and the selective membrane permeability for these ions
reticular theory
an obsolete scientific theory in neurobiology that stated that the nervous system is made up of a single interlinking network.
compare neuron doctrine
schwann cells
the principle glia of the peripheral nervous system. schwann cells wrap around axons to form the myelin sheath
sodium
the ion. one of the main players contributing to the membrane potential of neurons
sodium-potassium pump
an energy consuming enzyme that pumps sodium out of cells, while pumping potassium into cells. it is essential for maintaining the resting potential and therefore normal brain funciton
synapse
the junction between aneuron and another cell that forms the information transfer site between the two cells
vesicles
small membrane compartments that ctore and release neurotransmitters at the synapse
voltage-gated channel
gated membrane channels that open and close only at specific membrane potentials. voltage-gated channels are essential for the generation of action potentials
active touch
touch in which the observer plays an active role in touching and exploring an object usually with his or her hnds
cortical magnification
the exaggerated cortical representation of one part of a sensory dimension or surface compared to another
cutaneous senses
the ability to perceive sensations such as touch temperature and pain that are based on stimulation of receptors in the skin
dermis
the layer below the epidermis
epidermis
the outer layer of skin including a layer of dead skin cells
kinesthesis
the perception of body movements. it involves being able to detect changes in body position and movements based on proprioception and the vestibular system
mechanoreceptor
receptor that responds to mechanical stimulation such as pressure stretching or vibration
Meissner corpuscle (RA1)
a rapidly adapting mechanoreceptor in the skin. it has been proposed that the Meissner corpuscle is important for perceiving tactile slip and for controlling the force needed to grip objects
Merkel receptor (SA1)
a disk-shaed mechanoreceptor in the skin associated with slowly adapting fibres and the perception of fine details
nociceptor
a fibre that responds to stimuli that are damaging to the skin
pacinian corpuscle (RA2)
a mechanoreceptor in the skin with a distinctive elliptical shape. it transmits pressure to the nerve fibres inside it only at the beginning and end of a pressure stimulu, and is responsible for our persepction of vibration and the fine textures that are perceived when moving the fingers over a surface
passive touch
a situation in which a personal passively receives tactile stimulation
phantom limb
a persons continued perception (often including pain) of a limb such as an arm of a leg, even though the limb has been amputated
proprioception
the sensing of the position and movement of the limbs
rate code
a neuronal coding principle in which the firing rate of a neuron carries information about the stimulus. it is often associated with neural coding of magnitude (intensity of pressure, stretch, light intensity or loudness)
rapidly adapting receptor (RA)
mechanoreceptors that respond with bursts of firing just at the onset and offset of a pressure stimulus
the Meissner corpuscle and the pacinian corpuscle are rapidly adapting receptor
ruffini cylinder (SA2)
a mechanoreceptor structure in the skin associated with slowly adapting fibres. it has been proposed that the ruffini cylinder is involved in perceiving stretching
slowly adapting (SA) receptors
mechanoreceptors located in the epidermis and the dermis that repond with prolonged firing to continued pressure. the merkel receptor and ruffini cylinder are slowly adapting mechanoreceptors
somatosensory system
the system that includes the cutaneous senses (senses involving the skin) and proprioception (the sense of the position and the movement of the limbs
two-point threshold
the smallest separation between two points on the skin that is perceived as two points; a measure of acuity on the skin
amygdala
a subcortical structure that is involved in emotional responding and in processing olfactory signals
chemotopic map
the pattern of activation in the olfactory system in which chemicals with different properties create a map of activation based on these properties. for example there is evidence that chemicals are mapped in the olfactory bulb based on carbon chain length. also called odour maps
flavour
the perception that occurs from the combination of taste and olfaction
glomeruli
small structure in the olfactory bulb that receive signals from similar olfactory receptor neurons
one function of each glomerulus is to collect information about a small group of odorants
mitral cell
a neuron in the olfactory bulb that receive signals from similar olfactory receptor neurons and relays them to the brain
there are about 50,000 mitral cells in the human olfactory bulb
odorant
a molecule that is defined by its physiochemical characteristics, which are capable of being translated by the nervous system into the perception of smell
olfactory bulb
the structure that receives signals directly from the olfactory receptors. the olfactory bulb contains glomeruli which receives these signals from the receptors
olfactory epithelium
the region inside the nose that contains the receptors for the sense of smell
olfactory receptor
a protein string that responds to odor stimuli. different olfactory receptor neurons are equipped with different olfactory receptors
oral capture
the condition in which sensation from both olfaction and taste are perceived being located in the mouth
papillae
ridges and valleys on the tongue some of which contain taste buds
there are three types of papillae: fungiform, foliate and cirumvallate
population coding
a general principle of sensory processing according to which different values of perceptual attribute are coded by different patterns of activity in a whole population of neurons
recognition profile
the pattern of olfactory activation for an odorant indicating which ORNNs (olfactory receptor neurons) are activated by the odorant
retronasal rout
the opening of the oral cavity through the nasal pharynx into the nasal cavity. this route is the basis for the way smell combines with taste to create flavour
tastant
any stimulus that can be tasted
taste bud
a structure located within papillae on the tongue that contains the taste cells
taste cells
cells located in taste buds that cause the transduction of chemical or electrical energy when chemicals contact receptor sites or channels located at the tip of this cell
taste pore
an opening in the taste bud through which the tips of taste cells protrude. when chemicals enter a taste pore, they stimulate the taste cells and result in transduction
acoustic signal
the pattern of frequencies and intensities of the sound stimulus
amplitude
in the case of a repeating sound wave of a pure tone, amplitude represents the pressure difference between atmospheric pressure and the maximum pressure of the wave
auditory canal
the canal through which air vibrations travel from the environment to the tympanic membrane
auditory response area
the psychophysically measured area that defines the combinations of frequencies and sound pressure levels over which hearing functions
compex tone
a tone consists of two or more pure tones. the first harmonic of a complex tone is the pure tone with the lowest frequency in the frequency spectrum. the other components called higher harmonics have frequencies that are multiples of the fundamental frequency
decibel (dB)
a unit that indicates the pressure of a sound stimulus relative to a reference pressure: dB=20 log(p/p0) where p is the pressure of the tone and p0 is the reference pressure
frequency
the number of times per second that pressure changes of a sound stimulus repeat. frequency is measured in Hertz where 1 Hz = 1 cycle per second
frequency spectrum
a plot that indicates the relative energy (or amplitudes) of the various frequencies that make up an acoustic signal
harmonics
pure-tone components of a complex tone that have frequencies that are multiples of the fundamental frequency
hertz
the unit for designating the frequency of a tone. one Hertz equals one cycle per second
incus
the second of the three ossicles of the middle ear. it transmits vibrations from the malleus to the stapes
inner ear
the innermost division of the ear, containing the cochlea and the receptors for hearing
loudness
the perceived quality of sound that ranges from soft to loud. for a tone of a particular frequency, loudness usually increases with increasing decibels
malleus
the first for the ossicles of the middle ear. receives vubrations from the tympanic membrane and transmits these vibrations to the incus
middle ear
the small air-filled space between the auditory canal and the cochlea that contains the ossicles
middle ear muscles
muscles attached to the ossicles in the middle ear. the smallest skeletal muscle in the body they contract in reponseto very intense sounds and dampen the vibration of the ossicles
ossicles
three small bones in the middle ear that transmit vibrations from the outer to the inner ear
outer ear
the pinna and the auditory canal
oval window
a membrane covered hole in the cochlea that receives vibrations from the stapes
periodic tone
a tone which the waveform repeats
pinna
the part of the ear that is visible on the outside of the head
pitch
the perceived quality of sound anging from low to high that is most closely associated with the frequency of a tone
pure tone
a tone with pressure changes that can be described as a single sine wave
sound (percpetual)
the perceptual experience of hearing
sound (physical)
the physical stimulus for hearin
sound pressure level (SPL)
a designation used to indicate that the reference pressure used for calculating a tones decibel rating is set at 20 micropascals, near the threshold in the most sensitive frequency range for hearing
sound spectogram
a plot showing the pattern of intensities and frequencies of a sound stimulus
sound wave
pattern of pressure changes in a medium. most of the sounds we hear are due to pressure change in the air altough sound can be transmitted through water and solids as well
stapes
the last of the three ossicle in the middle ear. it recieves vibrations from the incus and transmits these vibration to the oval window of the inner ear
timbre
the perceived quality that distinguishes bwteen two tones that sound different even though they have the same loudness, pitch and duration. differences in timbre are illustrated by the sounds made by different musical instruments
tympanic membrane
a membrane at the end of the auditory canal that vibrates in response to vibration of the air and then transmits these vibrations to the ossicles in the middle ear. also called eardrum
acoustic prism
the way the cochlea separated frequencies entering the ear to create activity at different places along the basilar membrane
apex of cochlea
the end of the cochlea farthest from the middle ear
auditory space
perception of where sounds are located in space. auditory space extends around a listeners head in all directions existing wherever there is sound
azimuth
in hearing, specifies locations that vary from left to right relative to the listener
base of the cochlea
the part of the cochlea nearest the middle ear
basiliar membrane
a membrane that stretched the length of the cochlea and controls the vibration of the cochlear partition. physical properties of the baisilar membrane play a critical role for the frequency tuning
binaural cue
sound localization cue that involves both ears. interaural difference and interaural level difference are the primary binaural cues
characteristic frequency
the frequency at which a neuron in the auditory system has its lowest threshold
cilia
fine hairs the protrude from the inner and outer hair cells of the auditory system. bending the cilia of the inner hair cells leads to transduction
cochlea
the snail-shaped liquid–filled structure that contains the structures of the inner ear, the most important of which are the basilar membrane, the techtorial membrane and the hair cells
cochlear partition
a partition in the cochlea, extending almost its full length that separates the scala tympani and the scala vestibule. the organ of corti, which contains the hair cells is part of the cochlear partition
distance
how far a stimulus is from the observer.in hearing the distance coordinate specifies how far the sound source is from the listener
elevation
in hearind sound locations that are up and down relative to the listener
frequency tuning curve
curve relating frequency and the threshold intensity for activating an auditory neuron
hair cell
neuron in the cochlea that contains small hairs or cilis that are displaced by vibration of the basiliar membrane and fluids inside the inner ear. there are two kinds of hair cells: inner and outer
inner hair cell
auditory receptor cell in the inner ear that us primarily responsible for auditory transduction
interaural level difference (ILD)
the difference in the sound pressure or level between the left and right ears. this difference creates an acoustic shadow for the far ear. the ILD provides a cue for sound-localization for high frequency sounds
interaural sound difference (ITD)
when a sound is positioned closer to one ear than to the other, the sound reaches the close ear slightly before reaching the far ear., so tere is a difference in the time arrival at the two ears. the ITS provides a cue for sounds localization for low frequency sounds
outer hair cell
auditory receptor cells in the inner ear that amplify the responses of the inner hair cells by amplifying the vibration of the basilar membrane
organ of corti
the major structure of the cochlea partition, containing the basilar membrane the techtorial membrane and the receptors for hearing
place theory of hearing
the proposal that the frequency of a sound is indicated by the place along the organ of corti at which a nerve is firing is highest
Techtorial membrane
a membrane that stretches the length of the cochlea and is located directly over the hair cells. vibrations of the cochlea partition case the tectorial membrane to bend hair cells by rubbing against them
tonotopic map
an ordered map of frequencies created by the responding of neurons within structures of the auditory system. there is tonotopic map of neuron along the length of the cochlea, with neurons in the apex reponding best to low frequencies and neurons at the base responding beast to high frequencies
travelling wave
in the auditory system, vibrations of the basilar membrane in which the peak of vibrations travels from the base of the membrane to its apex
otolith organ
either of two mechanical structures (utricle and saccule) in the vestibular organs that sense both linear acceleration and gravity
semicircular canals
any of the three toroidal tubes in the vesibular organs that sense angular motion
vestibular organs
the set of five organs - three semicircular cancal and two otolith organs - located in each inner ear that sense head motion and head orientation with respect to gravity
vestibular system
the mechanism in the inner ear that is responsible for balance and sensing the position of the body
accommodation (focus)
in vision, bringing objects located at different distance into focus by changing the shape of the lens
blind spot
the small area where the potic nerve leaves the back of the eye. there are no visual receptors in this area, so small images falling directly on the blind spot cannot be seen
cones
cone-shaped photoreceptors in the retina that are primarily responsible for vision in high levels of illumination and for colour vision and detailed vision
cornea
the transparent focusing element of the eye that is the first structure through which light passes as it enters the eye. the cornea is the eyes major focusing element
eccentricity
the distance between a position on the retina and the center of fovea
electromagnetic spectrum
continuum of electromagnetic energy that extends from very-short-wavelength gamma rats to long-wavelength radio waves. visible light is a narrow band within this spectrum
emmetropia
the condition in which there in no refractive error because the refractive power of the eye is perfectly matched to the length of the eyeball
eye
the eyeball and its contents which include focusing elements, the retina and supporting structures
eyelid
a thin fold of skin that covers and protects the eye
fovea
a small area in the human retina that contains only cone receptros. the fovea is located on the line of sight, so that when a person looks at an object, the center of its image falls on the fovea
hyperopia
a condition causing poor vision in which people can see objects that are far away but do not see near objects clearly. also called far sightedness
iris
the coloured part of the eye, consisting of a muscular diaphragm surrounding the pupil and regulating the light entering the eye by changing the pupil size
illuminance
a photometric measure of the light incident on a surface (per unit area)
lens
the transparent focusing element of the eye through which light passes after passing through the cornea and the aqueous humor. the lens’s change in shape to focus at different distances is called accommodation
luminance
a photometric measure of the luminous intensity per unit area of light travelling in a given direction
myopia
an inability to see distant objects clearly. also called nearsightedness
optic nerve
bundle of nerve fibres that carry impulses from the retina to the lateral geniculate nucleus and other structure. each optic nerve contains about one million ganglian cell fibres
peripheral retina
the area of the retina outside the fovea
photon
a quantum of visible light (or other forms of electromagnetic radiation) exhibiting wave-particle duality (ie demonstrating properties of both waves and articles)
photopic vision
vision under well lit conditions (intensities are bright enough to stimulate cone receptors and bright enough to saturate the rod
photoreceptor
a light sensitive receptor in the retina of the eye
presbyopia
the inability of the eye to accommodate due to a hardening of the lens and a weakening of the cilary muscles. it occurs as people get older
pupil
the opening through which light reflected from objects in the environment enters the eye
reflectance
the percentage of light reflected from an object as a function of wavelength
retina
a complex network of cells that covers the inside back of the eye. these cell include the receptors, which generate eectical signal in resonse to light, as well as horizontal;, bipolar, amacrine and ganglion cells
rod
a cylinder shaped photoreceptor in the retina that is responsible for vision at low levels of illumination
scotopic vision
vision under low light conditions (light intensities that are bright enough to stimulate the rod receptors but not too dim to stimulate the cone receptors)
selective reflection
when an object reflects some wavelength of the spectrum more than others. selective reflection is associated with the perception of chromatic colour
visible light
the band of electromagnetic energy that activated the visual system and that can be perceived. for humans 400-700 nm
visual angle
the angle of an object relative to an observers eyes. this angle can be determined by extending two lines from the eye - on to one end of an object and other to the other end of the object. because of an observers visual angle is always determine relative to an observer, its visual angle changes as the distance between the object and the observer changes
wavelength
for light energy the distance between one peak of light and the next peak
absorption spectrum
a plot of the amount of light absorbed by a visual pigment versus the wavelength of light
amacrine cell
a neuron that transmits signals laterally in the retina. amacrine cells synapse with bipolar cells and the ganglion cells
bipolar cell
a retinal neuron that receives inputs from the visual receptors and sends signals to the retinal ganglion cells
center-surround organization
arrangement of a neurons receptive field in which one area is surrounded by another area. stimulation of the center and surround causes the opposite responses
ganglion cell
a neuron in the retina that receives inputs from bipolar an amacrine cells. the axon of the ganglion cells are the nerve fibres that travel out of the eye in the optic nerve
horizontal cell
a neuron that transmits signals laterally across the retina. horizontal cell synapse with receptors and bipolar cells
lateral geniculate nucleus (LGN)
a structure in the thalamus tat receives input from the retinal ganglion cells and has input and output connections to the visual cortex
lateral inhibition
inhibition that is transmitted laterally across a nerve circuit. in the retina, lateral inhibition is transmitted by the horizontal and amacrine cells
M cells
ganglion cells with large centre-surpund receptive fields that are rather indifferent tot he wavelength of light and adapt rapidly
optic chiasma
the part of the brain where the optic nerves partially cross. the optic chiasm is located at immediately below the hypothalamus
optic nerve
a paired nerve that transmits visual information from the retina to the LGN and superior colliculus
outer segment
the part of the rod and cone visual receptors that contains light-sensitive visual pigment molecules (the retinal bound top membrane proteins)
P cells
ganglion cells with small center-surround receptive fields that are sensitive to the wavelength pf light and adapt slowly
phototransduction
the process by which light energy is transduced into electrical energy in the rod and cone cells in the retina of the eye
retinal
a molecule bound to membrane proteins in photoreceptors that can absorp photons. it is hence the chemical basis of animal vision
retinotopic map
a map on a structure in the visual system, such as the lateral geniculate nucleus or the primary visual cortex that exhibits a spatial correspondence to the retina. in retinotopic maps, locations adjacent to each other correspond to locations adjacent to each other on the retina
spontaneous activity
neural activity in the absence of an explicit task, such as sensory input or motor output. it is also referred to as resting-state activity
striate cortex
the primary visual cortex, also called V1 or brodmann area 17
superior colliculus
an area in the brain that is involved in controlling eye movements and other visual behaviours. this area receives about 1o percent of the retinal ganglion cell fibres that leave the eye in the optic nerve
additive colour mixing
a colour system that starts with dark (typically black) and that creates a wider range of colours by adding light. dditive colour mixing is used by your computer monitor
colour blindness
a condition in which a person perceives no chromatic colour. this can be caused by absent or malfunctioning cone receptors or by cortical damage
colour deficiency
people with this condition (sometimes incorrectly called blindness) see fewer colours than people with normal colour vision
deuteranopia
a form of red-green colour dichromatism caused by lack of the middle wavelength cone pigment
dichromat
a person who has a form of colour deficiency due to the absence of one cone receptor type
monochromat
a person who is completely colour-blind and therefore sees everything as black, white or shades of grey. monochromats generally have only one type of functioning receptros, usually rods
monochromatic light
light that contains only a single wavelength
munsell colour system
a colour space that specifies colours based on three colour dimensions: hue, value (lightness) and chroma (colour purity)
opponent theory
a theory of colour vision that is based on the premise that there are three opponent channels (black-white, red-green and blue-yellow) subserving colour vision
protanopia
a form of re-green dichromatism caused by a lack of the long wavelength cone pigment
subtractive colour mixing
a colour system that starts with light (typically white) and that creates a wider range of colours y adding pigments (by subtracting specific wavelengths from the white light spectrum). subtractive colour mixing occurs when you are mixing paint
trichromat
a person with normal colour vision
trichromatic theory
a theory of colour vision that is based on the premise that there are three classes of receptors (L,M and S cones) subserving colour vision
trianopia
a form of dichromatism thought to be cause by a lack of short-wavelength cone pigment
bimodal neuron
a neuron that responds to stimuli associated with more than one sense
binding
the process by which features within one modality (colour, form, motion and location in vision eg) are combined to create the percept of a coherent object. binding can also occur across sense, as when touch and vision are associated with the same object
binding problem
the problem of how neuronalactivity in many separated areas in the brain is combined to create a perception of a coherent object
concurrent
the subjective experience in synesthesia triggered by an inducer stimulus
easy problem of consciousness
the problem determining the relationship between physiological processes like nerve firing and perceptual experience. note that this involves determining a relationship, not a cause
grandmother cell
a hypothesised type of neuron that responds only to a very specific stimulus, such as a persons grandmother
hard problem of consciousness
the problem determining how physiological processes, such as ion flow across nerve membranes, cause different perceptual experiences
inducer
a term to describe the stimulus that elicits synesthesia
mind-body problem
one of the most famous problems in science: how do physical processes such as nerve impulses or soium and potassium molecules flowing acorss membranes become transformed into the richness of perceptual experience
multimodal
the involvement of a number of different sense in determining perception. for example body perception can be influenced by information from a number of different sensory signals including for example vision and touch
neuronal correlates of consciousness (NCC)
connections between the firing of neurons and perceptual experience
synesthesia
a condition in which stimulation of one modality (such as vision) results in an experience in another modality (such as touch). for example a person with mirror-touch synesthesia, who observes another person being touched may experience touch on the same part of his or her own body
absolute threshold
the minimum stimulus necessary for an observer to detect a stimulus
bias
a measure for the extent to which one response is more probable than another. bias is independent of sensitivity
correct rejection
in a signal detection experiment, saying no i don’t detect a signal on a trial in which the signal is not presented
difference threshold
the minimal detectable difference between two stimuli. also called just noticeable difference
false alarm
in a signal detection experiment saying yes i detect the stimuli on a trial in which the signal is not presented
Fechner’s law
a principle describing the relationship between a stimulus and the resulting sensation that says the magnitude of subjective sensation increases proportionally to the logarithm of the stimulus intensity
hit
in a signal detection experiment saying yes i detect the signal whien the signal is present
miss
in a signal detection experiment saying no i don’t detect a signal when the signal is present
psychophysics
traditionally the term refers to quantitative method of measuring the relationship between properties of the stimulus and the subjects experince
receiver operating characteristic curve ROC
in a signal detection experiment the graphical plt of the hit rate as a function of the false alarm rate. if these are the sam, observers cannot distinguish between signal and noise. as the observers sensitivity increases, the curve bows toward the upper left corner - a point that represents perfect sensitivity
response criterion
in a signal detection experiment the subjective magnitude of a stimulus above which the participant will indicate that the stimulus is present
sensitivity
a measure for how hard or easy it is for a subject to detect that a target stimulus i present. it can be computed based on hit and false alarm rates. also called d’ (d prime)
signal detection theory
a theory stating the detection of a signal depends both on the participants sensitivity to the signal an on the participants response bias
webers law
a law stating that the ratio of the difference threshold (delta l)to the stimulus intensity (l) is constant. according to the relationship doubling the value of the stimulus intensity will cause a doubling of the difference threshold. the ratio deltal/l is called webers fraction
