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70 Cards in this Set
- Front
- Back
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Olfactory: receptor cell, support cell, basal cell
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Receptor cell: has olfactory cilia, axons pass through cribriform plate, last about 2 mos.
support cell: produces mucous basal cell: differentiates into receptor cells |
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Describe characteristics of olfactory transduction
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G-protein coupled receptors bind variety of odorants to vary degrees --> increases intracellular cAMP --> ion channels open --> depolarization
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What is the role of the glomeruli in olfaction?
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receptor cells with the same type of receptor converge on one or more glomeruli
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What is the role of mitral/tufted cells in olfaction?
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M/T cells project into glomeruli to olfactory bulb/tracts and into paleocortex and limbic system components
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What is the role of periglomerular cells in olfaction?
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PG cells cause lateral inhibition between M/T cells due to GABA and D2-mediated dopamine effects --> leads to sharper discrimination of odors
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What are the roles of support cells, basal cells, and receptor cells in taste buds?
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Receptor cell (not a neuron) detects taste via channel activity
basal cells differentiate into receptor cells support cells: nothing too important |
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What are the 4 (5) basic taste qualities?
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Salt, sour, bitter, sweet, (umami)
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How are each of the 4 taste qualities detected?
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salt: sodium channels
sour: proton-linked channels bitter: G-protein coupled receptors sweet: G-protein coupled receptors |
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Pathway for taste signals from tongue to cortex
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chroda tympani, glossopharyngeal nerve, vagus nere --> solitary nucleus --> VPM (non-decussating) --> post-central cortex and insular neocortex
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Scotopic vs. photopic vision
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Scotopic - rod-driven, dim light
Photopic - cone-drive, bright light |
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What are the components of a rod cell?
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layers of rhodopsin discs, large collection of mitochondria, synaptic ribbon
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Describe the basic interaction of rods and cones with light
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light causes the hyperpolarization of rods and cones by causing the closure of cGMP-gated channels; graded based on intensity of light
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The retina system: rods
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connected to rod bipolars via triad synapse --> glutamate inhibits rod bipolars
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The retina system: rod bipolar cells
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rod bipolar cells transmit signals when light is present to amacrine cells, which can be sign-conserving or sign-inverting
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The retina system: amacrine cells
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sign-conserving amacrine cells synapse on "on" cone bipolar cells; sign-inverting amacrine cells synapse on "off" ganglion cells
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The retina system: cones
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Cones transmit info to "off" cone bipolars via flat synapse and transmit info to "on" cone bipolars via triad synapse
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The retina system: cone bipolars
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active cone bipolars directly activate corresponding retinal ganglion cells
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The retina system: horizontal cells
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synapse on triad synapses and cause lateral inhibition
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The parvocellular retinal system
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single cone, bipolar, ganglion cell --> midget pathway, for acuity; near fovea
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The magnocellular retinal system
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bipolar cells that synapse over a range of cones for motion detection
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What are the projection sites of the optic tracts?
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dorsal lateral geniculate nuclei
superior colliculus accessory optic nuclei pretectal area retinohypothalamic tract |
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Describe the 4-neuron arc of the pupillary reflex (constriction)
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ispilateral neuron from retina to pretectal area
bilaterally synapsing neuron to Edinger-Westphal nuclei Neurons synapse on ciliary ganglia neurons synapse on pupillary constrictor muscles |
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Describe the 3-neuron arc of pupillary dilation
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neuron originates in hypothalamus and passes to lateral horn
neuron enters sympathetic trunk and synapses in superior cervical ganglion (also inhibition of pretectal area here) neuron synapses on pupillary dilator muscle |
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What is the role of melanopsin-containing retinal ganglion cells?
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react to light intensity, mediate pupillary reflex and retinohypothalamic tract
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What is the monocular crescent?
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Part of visual hemifield of one eye that is not seen by the other eye (due to nose)
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Where does the magnocellular and parvocellular input go in the lateral geniculate bodies (laminae)?
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Magnocellular input - laminae 1, 2
Parvocellular input - laminae 3-6 |
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Describe the visual pathways from LGN to calcarine cortex?
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Meyer's loop through temporal lobe corresponds to upper visual field (lower calcarine cortex)
Direct parietal pathway corresponds to lower visual field (upper calcarine cortex) |
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What is the result of a striate (calcarine lesion)?
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homonymous scotomas (elicited via visual field perimetry)
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What are results of extrastriate lesions?
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temporal lesions - deficits in visual memory and recognition
parietal lesions - visual inattention ventral occipito-temporal lesions - loss of facial recognition |
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What results in heteronymous deficits?
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damage to optic chiasm, LGNs, or optic radiations
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How do the medial and lateral sides of the LGN correspond to visual fields?
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medial - lower, contralateral visual field
lateral - upper, contralateral visual field |
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Describe the visual receptive fields of "on" and "off"-center neurons
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concentric, center-surround organization: "on" cells activated when light hits middle area, inhibited when light hits surrounding area (opposite for "off" cells)
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What are "X" neurons and "Y" neurons?
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X neurons - parvocellular, sustained response to stimulus
Y neurons - magnocellular, fire bursts of potentials at initiation and termination of stimulus |
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Cells of the visual cortex: concentric cells, simple cells, complex cells (hypercomplex cells)
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concentric cells: receptive fields match those of retina and LGN
simple cells: elongated receptive fields that respond to particular orientation complex cells: respond to same orientation simple cells across retina hypercomplex cells + feature detectors even higher level |
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What are the ocular dominance columns of the visual cortex?
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"zebra-stripe" pattern of neurons projecting from single eye in the 4th layer of calcarine cortex
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What are the orientation columns of the visual cortex?
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columns perpendicular to cortical surface that contain neurons that respond to same orientation; adjacent columns are stimulated by slightly different angles; these are in layers 2, 3, 5, 6
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Describe the parallel processing of visual information
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Parvocellular signals go to V4 and then to inferotemporal corex: ventral stream --> perception
Magnocellular signals go to MT (middle temporal area): dorsal stream --> motion |
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What are the cortical efferent pathways from visual cortex?
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cortico-striate (to basal ganglia)
cortico-cortical coritco-tectal cortico-ponto cerebellar |
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Describe how stereoposis works
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temporally and nasally displaced images activate specific neurons, signals integrated in splenium of corpus callosum --> leads to vertical meridian stereopsis
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What are the three cones for color vision?
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Short: blue cone
Middle: green cone Long: red cone |
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What is protanomaly? Protonopia? Deuteranomaly? Deuteranopia?
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Protanomaly - abnormal red cone
Protonopia - absent red cone Deuteranomaly - abnormal green cone Deuteranopia - absent green cone |
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Merkel's receptor: depth, size of receptive field, adaptation speed, type of sensation
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cutaneous, small, slowly adapting, very fine touch
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Meissner's receptor: depth, size of receptive field, adaptation speed, type of sensation
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cutaneous, small, rapidly adapting, vibration/sense of slip
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Ruffini's corpuscle: depth, size of receptive field, adaptation speed, type of sensation
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deep, large, slowly adapting, pressure/stretch of skin
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Pacinian's corpuscle: depth, size of receptive field, adaptation speed, type of sensation
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deep, large, rapidly adapting (fastest), 100-300 Hz vib/changes in pressure
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Structure of Pacinian corpuscle and nature of firing
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Encased in multiple lamellae that act as high pass filter
APs with initiation and termination of stimulus |
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What are some patterns in the density of receptors on the palm?
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Merkel's and Meissner's receptors densest at fingertips
Ruffini's and Pacinian corpuscles less dense at finger tips |
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Pattern in receptor field size across the body?
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receptor fields increase in size form distal to proximal on the body
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What are the characteristic of hair receptors?
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very rapidly adapting and very sensitive, silent when hair is not moving
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What are the two main types of free nerve endings?
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temp/non-discriminative touch and nociception specific (pain)
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What type of nerve fibers make up free nerve endings?
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A-delta and C fibers
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Where are free nerve endings found and how specific are they?
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Found in skin, muscle, joints, and viscera
Can be very specific or polymodal |
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What is the axon reflex?
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Painful stimulus activates pain-receptor, releases neuro-active peptide (e.g. substance P), which passes into branches of neuron widening response (flare)
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What is the fate of A-alpha and A-beta fibers entering the dorsal horn?
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80% will ascend to cuneate/gracile nuclei
20% will synapse in dorsal horn |
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What is damaged, respectively, in medial medullary syndrome and lateral medullary syndrome?
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medial medullary syndrome - medial lemniscus damaged
lateral medullary syndrome - spinothalamic tract damaged |
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Describe the organization of the ventrobasal complex (VPL + VPM) of the thalamus - where do the inputs go?
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Deep inputs remain in the "shell"
Cutaneous inputs project into core |
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Describe the organization of the ventrobasal complex (VPL + VPM) of the thalamus - where do the outputs go in the cortex?
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Proprioception --> 3a
Rest of the shell --> 2 Core --> 1, 3b |
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How would you describe the organization of the sensory cortex?
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Areas of the body are made precisely and repeatedly in the cortex, with receptor projections in columns (slowly adapting adjacent to rapidly adapting)
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What are the two pathways from the primary somatosensory cortex (S1)?
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Action pathway: to posterior parietal cortex to premotor cortex
Perception pathway: to secondary somatic sensory cortex (SII) to limbic system |
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What is 1st pain? Second pain?
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1st pain: initial, localized pain (A-delta fibers)
2nd pain: delayed, burning, aching pain (C fibers) |
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What is sensitization? Wind-up? (nociception)
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Sensitization: increased responsiveness of pain receptors
Wind-up: increased responsiveness of central pain neurons |
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What is the difference between hyperalgesia and allodynia?
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Hyperalgesia is increased pain with repeated painful stimuli
Allodynia is pain from normal stimulation |
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What is neuralgia? What is causalgia?
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Neuralgia is pain along the course of nerves
causalgia is spasms of neuralgic pain |
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What is the effect of anoxia vs. anesthetics on A-delta, C fibers?
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Anoxia blocks A-delta fibers
Anesthetics block C fibers |
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Characteristics of free nerve endings for pain and temperature
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All pain and temp receptors can be activated chemically, pain-temp hits around 10C and 45C, pain receptors are silent without a stimulus
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A-delta and C-fibers enter the dorsal horn at which laminae?
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I, II, and V
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Where is pain transmitted throughout the brain?
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cingulate cortex, primary sensory cortex, insular cortex (and frontal and parietal cortices)
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What is the "gate" pain theory?
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Ascending large fiber pathways and descending pathways inhibit the transmission of pain in the dorsal horn
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How do ascending large fiber pathways influence ascending pain fiber pathways?
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Can synapse directly, exciting pain neurons, or can synapse on inhibitory interneurons, decreasing pain
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The middle cingulate cortex pathway and the anterior cingulate cortex pathway are responsible for what with regards to pain?
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Middle cingulate cortex: pain localization
Anterior cingulate cortex: affect-motivation |
