Neuroscience Exam #2 Baylor

absorption spectrum

A graph of the ability of a substance to absorb light of different wavelengths

Accomodation

the process of adjusting the configuration of the lenses to bring images into focus on the retina

Acuity

the ability to see into the details of objects

Agnosia

a failure of recognition of sensory stimuli that is not attributable to a sensory or to verbal or intuectual impairment

Akinetopsia

a deficiency in the ability to see movement progress in a smooth fashion, which often comes from damage to the MT area

amacrine cells

retinal neurons that are specialized for lateral communication (that is to say, signals sent between neurons)

area MT

an area of cortex, located near the junction of the temporal, parietal, and occipital lobes, whose function seems to be the perception of motion.

binocular

cells in the visual system that are binocular respond to stimulation of either eye

binocular disparity 

the difference in the position of the same image on the 2 retinas of one person

bipolar cells

bipolar neurons that form the middle layer of the retina

blindsight

the ability to respond to visual stimuli in a scotoma without conscious awareness of those stimuli

blind spot

the area on the retina where the bundle of axons from the retinal ganglion cells leave the eye as the optic nerve

ciliary muscles

the eye muscles that control the shape of the lenses

color constancy

The tendency of an object to appear the same color even when the wavelengths of light that it reflects change

complementary colors

pairs of colors that produce white or gray when combined in equal measure 

completion 

the visual systems automatic use of info obtained form receptors around the blind spot, or scomata, to create a perception of the missing portion of the retinal image

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

component theory

the theory that the relative amount of activity produced in 3 different classes of cones by light determines its perceived color

Cones

the visual receptors in the retina that  mediate high acuity color vision in good lighting

conscious awareness

the awareness of one’s perceptions; typically inferred from the ability to verbally describe them

contrast enhancement

the intensification of the perception of edges

control of behavior versus conscious perception theory

the theory that the dorsal stream mediates behavioral interactions with objects and the ventral stream mediates conscious perception of objects

dorsal stream

the group of visual pathways that flows from the primary visual cortex to the dorsal prestriate cortex to the posterior parietal cortex

duplexity theory

the theory that cones and rods mediate photopic and scotopic vision, respectively

fixational eye movements

involuntary movements of the eyes that occur when a person tries to stare at a point

fovea

the central indentation of the retina, which is specialitzed for high acuity vision

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

hemianopsic

having a scotoma that covers half of the visual field

horizontal cells

retinal neurons whose specialized function is lateral communication

inferotemporal cortex

the cortex of the inferior temporal lobe, in which is located an area of secondary visual cortex

Integratrion 

adding or combining a number of individual signals into one overall signal 

Magnocellular layers

the layers of the lateral geniculate nuclei that are composed of neurons with large cell bodies; the bottom 2 layers

monocular

involving only one eye

nasal hemiretina

the half of each retina next to the nose

occipital face area

an area in the occipital lobe that is implicated in the processing of faces

Off-center cells

visual neurons that respond to light shone in the center of their receptor fields with “off"“ firing and to lights shone in the periphery of their receptive fields with “on” firing

On-center cells

Visual neurons that respond to lights shone in the center of their receptive fields with “on” firing and to lights shone in the periphery of their receptive fields with “off” firing

opponent=process theory

the theory that a visual receptor or a neuron signals one color when it responds one way and signals the complementary color when it responds the opposite way.

parvocellular layers

the layers of the lateral geniculate nuclei that are composed of neurons with small cell bodies; the top 4 layers

perimetry test

the procedure used to map scomatas

photopic spectral sensitivity curve

the graph of the sensitivity of cone mediated vision to different wavelengths of life

photopic visons

cone mediated vision, which predominates when lighting is good

posterior parietal cortex

the posterior area of the parietal cortex

prestriate cortex

the band of tissue in the occipital lobe that surrounds the primary visual cortex and contains ares of secondary visual cortex

primary visual cortex

the area of the cortex that receives direct input from the lateral geniculate nuclei (striate cortex)

prosopagnosia

visual agnosia for faces

purkinje effect

in intense light, red and yellow wavelenghts look brighter than blue or gree, and in dim light, the exact opposite is true.

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.

retina-geniculate-striate pathway

the major visual pathway from each retina to the primary visual cortex via the lateral geniculate nuclei of the thalamus

retinex theory

land’s theory that the color 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

retinotopic

organized, like the primary visual cortex, according to a map of the retina

rhodopsin

the photopigment of rods

rods

the visual receptors in the retina that mediate achromatic, low-acuity vision under dim light

saccades

the rapid movement of the eyes between fixations

scotoma

an area of blindness produced by damage to, or a disruption of, an are of the visual system

scotopic spectral sensitivity curve

the graph of the sensitivity of rod-mediated vision to different wavelengths of light

scotopic vision

rod mediated vison which predominates in dim light

secondary visual cortex

areas of cerebral cortex that recieve most of their input from the primary visual cortex

sensitivity

in vision, the ability to detect the presence of dimly lit objects

simple cells

neurons in the visual cortex that respond maximally to straight-edge stimuli of a particular width and orientation

surface interpolation

the process by which we perceive surfaces; the visual system extracts info about edges and from it infers the appearance of large surfaces

temporal hemiretina

the half of each retina next to the temple

transduction

the conversion of one form on energy to another

ventral stream

the group of visual pathways that flows from the primary visual cortex to the ventral prostrate cortex to the inferotemporal cortex

visual agnosia

a failure to recognize visual stimuli that is not attributable to sensory, verbal, or intellectual impariment

visual association cortex

areas of cerebral cortex that receive input from areas of secondary visual cortex as well as from secondary ares of other sensory systems

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 things are

ageusia

the inability to taste

anosmia

the inability to smell

anosognosia

the common failure of neuropsychological patients to recognize their own symptoms

anterior cingulate cortex

the cortex of the anterior cingulate gyrus

anterolateral system

a major somatosensory pathway that ascends in the anterolateral portion of the spinal cord and tends to carry info related to pain and temperature

association cortex

the area of the cortex that receives input from more than one sensory system

astereognosia

an inability to recognize objects by touch that is not attributable to a simple sensory deficit or to an intellectual impairment

attentional gaze

the shift in attention from one perceptual shift to another

auditory nerve

the branch of cranial nerve VIII that carries auditory signals from the hair cells in the basilar membrane

basilar membrane 

the membrane of the organ of Corti in which the hair cell receptors are embedded 

binding problem

when the brain combines individual sensory attributes to produce integrated perceptions

bistable figures

a stimulus that produces 2 alternating perceptions

bottom-up

a sort of neural mechanism that involves activation of higher cortical areas by lower cortical areas

change blindness

the difficulty perceiving major changes to unattended-to parts of a visual image when changes are introduced during brief interruptions in the presentation of the image

Charles Bonnet Sydrome

a condition, where affected individuals experience rich and complex hallucinations

chemotopic

organized, like the olfactory bulb, according to a map of various odors. 

cochlea

the long, coiled tube in the inner ear that is filled with fluid and contains the organ of corti and its auditory receptors

cocktail-party phenomenon

the ability to unconsciously monitor the contents of one conversation while consciously focusing on another.

contralateral neglect

a disturbance of the patients ability to respond to stimuli on the side of the body opposite to a site of brain damage, usually the left side of the body following damage to the right parietal lobe

dorsal-column medial-lemniscus system

the division of the somatosensory system that ascends in the dorsal portion of the spinal white matter and tends to carry signals related to touch and proprioception

dorsal columns

the somatosensory tracts that ascend in the dorsal portion of the spinal cord white matter

exteroceptive sensory systems

those sensory systems responsible for detecting stimuli in an organisms external enviroment

flavor

the combined impression of taste and smell

fourier analysis

a mathematical procedure for breaking down a complex wave form into component sine waves of various frequencies

free nerve endings

neuron endings that lack specialized structures on them and that detect cutaneous pain and changes in temp

functional segregation

organization into different areas, each of which performs a different function; for example, in sensory systems, different areas of secondary and association cortex analyze different aspects of the same sensory stimulus

hair cells

the receptors of the auditory system

hierarchical organization

organization 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

medial dorsal nuclei

the thalamic relay nuclei of the olfactory system

medial lemniscus

the somatosensory pathway between the dorsal column nuclei and the ventral posterior nucleus of the thalamus

neuropathic pain

severe chronic pain in the absence of a recognizable pain stimulus

olfactory bulbs

their output goes primarily to the amygdala and piriform cortex

olfactory glomeruli

discrete clusters of neurons that lie near the surface of the olfactory bulbs