Term
| Rods (Photoreceptor in retina) |
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Definition
- scotopic vision (dark vision)
- sense light intensity
- dominate in the periphery, therefore easier to see a dim object when you dont foveate at it
- many rods converge on a single postsynaptic cells (lower acuity, higher sensitivity) |
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Term
| Cones (Photoreceptor in retina) |
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Definition
- photopic vision (light vision)
- each are turned to absorb preferentially R/G/B light (in humans)
- clustered densely in the center of the retina (at the fovea), allows for high acuity and small receptive fields
- 1:1 contacts with postsynaptic cells |
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Term
| Horizontal cells (in retina) |
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Definition
- transmit information between adjacent photo receptors
- receive input of Glutamate from photoreceptors
- inhibit glutamate release from a neighboring rod/cone through release of GABA |
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Term
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Definition
- occurs in the retina with prolonged light stimuli
- cGMP-gated channels close in photoreceptors
- closure reduces Ca & Na influx
- negative feedback loop:
- decrease in Ca activates guanylate cyclase
- guanylate cyclase makes more cGMP
- cGMP gates the channel and opens it again
- functionally equivalent to desensitization -- response diminishes despite continued presence of stimulus |
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Term
Phototransduction Pathway
(Little Asians Attends Homeroom at Counter-Strike High-School) |
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Definition
- all happens in photoreceptors (rods/cones)
1. light is absorbed by rhodopsin (changes from 11-cis to all-trans isomer)
2. Conformational change of rhodopsin activates G-protein called transducin
3. Activation of transducin activates phosphodiesterase (hydrolyzes cGMP)
4. cGMP hydrolysis closes cGMP-gated channels
5. Closure of cation-selective channels (cGMP-gated channels) hyperpolarizes the photoreceptors
6. Photoreceptors stop/slow release of glutamate due to hyperpolarization |
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Term
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Definition
- photopigment in the retina
- is retinal -- meaning it is a light absorbing chromophore
- is coupled to one of many opsins (proteins) that allow retinal to absorb particular wavelengths of light |
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Term
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Definition
- 2 types: rods & cones
- resting potential is very depolarized (~40mV)
- leaky K+ channels pushing towards -90mV
- CNG pushing it to 0mV
- they stop releasing glutamate in the presence of light |
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Term
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Definition
- focusing light by adjustment of refraction
- focus is adjusted by ciliary muscles
- ciliary muscles change the shape of the lens |
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Term
| Bipolar Cells (in retina) |
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Definition
On-center Bipolar Cell
- depolarizes when Glutamate release slows
- mGlu-R -- activation of receptor leads to closure of CNG gated cation channels and therefore hyperpolarizes when Glutamate is released and depolarizes when Glutamate release is slowed/stopped
Off-center Bipolar Cell
- hyperpolarizes when Glutamate release slows
- AMPA/KA-Rs -- therefore bipolar cells depolarize in the presence of glutamate and hyperpolarize in the absence of glutamate |
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Term
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Definition
- has 5 types of neurons --> photoreceptors, bipolar cells, ganglion cells, horizontal cells, amacrine cells
- retina is part of the CNS |
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Term
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Definition
- when an on-center bipolar cell is inhibited by light in the periphery of its receptive field
- this happens because it is excited by light in the center of its receptive field |
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Term
| Ganglion Cells (in retina) |
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Definition
- the only retinal cells that produce action potentials because they have voltage-gated Na channels
On-center Off-surround
- produces APs if light in center of RF and darkness in surround
- reduce/abolish firing of APs if light surrounding and dark in center
Off-center On-surround
- opposite of on-center off-surround |
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Term
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Definition
- formed by the axons of ganglion cells
- project to the Lateral Geniculate Nucleaus (LGN) |
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Term
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Definition
- LGN is in the thalamus
- LGN projects to the primary visual cortex(specifically, cells in layer IV - 6 layers total)
- projection is orderly (projects onto visual cortex like the map on the retina - retinotopic map)
- visual cortical neurons' RFs are bars which are 'orientation selective' depending on which way the bar is rotated
- visual cortical neurons fire APs in response to light stimulus of a particular orientation in a particular part of visual space |
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Term
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Definition
- by Hebb
- process of learning must have more than one stage
- short-term: most likely electrical, quickly initiated and holds the memory transiently
- long-term: possibly structural (new synapses), long lasting memories |
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Term
| Sound Localization of Owls |
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Definition
- ICC receives certain frequencies, along with a time delay (between ears) which is mapped onto a certain space of the ICC
- ICC prjects to a certain space with corresponding time delay in the ICX
ICX projects onto the OT (optic tectum)
- projection of ICX onto OT directs head saccade to a particular location in space (Azimuth for owls) |
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Term
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Definition
- misaligns auditory and visual cues in owl
- map shift occurs between ICC and ICX
- map shift causes shift in OT
- owl makes new axons from ICC to ICX in order to account for the shift |
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Term
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Definition
Outer -> Middle -> Inner
- pinna --> ear canal --> ear drum
- ear drum --> ossicles --> oval window
- cochlea |
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Term
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Definition
- hammer (malleus) --> anvil (incus) --> stirrup (stapes)
- 3 little bones
- in middle ear, where it's filled with air
- huge pressure increase because area decreases by a lot, force increases
- Pressure = Force/Area |
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Term
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Definition
- myosin 1c associated with tiplinks (cadherin 23) and actin filaments in hair bundle
- rachets down the actin to relieve tension in tiplink
- relieving of tension in tiplinks closes ion channels
- hyperpolarizes cells
- if loud noises, fuck up different sections, cant reheal/regenerate b/c tiplinks broken |
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Term
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Definition
- inner hair cells: transduce sound
- outer hair cells: amplify or attenuate sound using prestin proteins "cochlear amplifiers"
- tiplinks open cation channels, which allow Ca to flow in
- Ca flows in (depolarizes cell), binds to Ca dependent K channel (opens it)
- K flows in (hyperpolarizes cell)
ANDDD its a cycle. |
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Term
| Sensory Systems Pathway (General) |
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Definition
sensory receptors --> brainstem --> thalamus --> cortex
- exception: olfactory (circumvent the brainstem to go to the puriform cortex) |
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Term
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Definition
- haircells sit on top of this
- base: stiff and narrow
- apex: wide and flexible
- as flexibility increases, resonant frequency decreases |
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Term
| Interaural Intensity Difference (IID) |
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Definition
- high frequencies
- creates sound shadow on one side of your head
- sound you get is a more intense in one ear and less intense in the other ear
- cue as to where things are (azimuth) |
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Term
| Interaural Timing Difference (ITD) |
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Definition
- low frequency sounds
- sound hits both ears at different time
- place theory model (AP's coincide at a neuron in the MSO and then you know where the sound is coming from) |
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Term
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Definition
| - detect sound from both ears |
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Term
| Olfactory/Gustatory Receptor Cascade Pathway (Chemical Stimuli) |
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Definition
1. Odorant (or Tastant) binds to receptor cells
2. Activation of G-protein in olfactory neurons (Golf)
3. Golf activates ACIII (adenylyl cyclase III)
4. ACIII increases cAMP production
5. cAMP binds to CNG-gated channels (& opens it)
6. Na/K/Ca flow into the cell
7. Ca binds to Ca gated Cl channel
8. Cl flows out of the cell
9. Depolarization of cell leads to firing of APs |
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Term
| Heat/Cold Sensitive Channels |
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Definition
Heat:
- TRPV1 - TRPV4 (TRPV3 & 4, thermoceptors NOT nociceptors)
Cold
- TRPA1: noxious cold
- TRPM8: menthol |
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Term
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Definition
- noxious heat & capsaicin
- amplitude of heat or capsaicin evoked currents is increased by application of protons
- detection of non-noxious stimuli goes through different pathways than detection of noxious stimuli
- TRPV1 channels are expressed in dorsal root ganglion (DRG)
- greater stimuli causes more depolarization of TRPV1 channels which causes more APs which causes more pain |
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Term
| Dorsal Root Ganglion (DRG) |
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Definition
- clusters of sensory cells just outside the spinal cord
- sense pain
- APs in DRG send signal to higher centers of the brain (which detect pain)
- only have N-type Ca channels |
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Term
| Transformation (of info from sensory input to motor output) |
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Definition
1. Transduction of stimulus
- from physical to electrical signal
- done by sensory receptor cells which are at the periphery of the brain
2. Trasmission of the stimulus to central brain regions
- signals can diverge with transform the signal in distinct ways |
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Term
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Definition
- many sensory receptors have no axons, but rather, increase in stimulus changes the voltage
- photoreceptors --> retina
- auditory hair cells --> cochlea
- vestibular hair cells --> otolithic organs (to detect head position)
- mechanoreceptors - transduce pressure --> skin and muscles
- thermoceptors - transduce temperature --> skin
- nociceptors - transduce pain --> on skin and internal organs
- chemoreceptors --> olfactory epithelium & tongue |
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Term
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Definition
Vision --> light stimuli
Audition --> sound=mechanical stimuli
Olfaction --> chemical stimuli
Gustation --> chemical stimuli
Somatosensation --> mechanical
Proprioception (sense of location/position of ones body) --> mechanical stimuli
Vestibular sense (sense of balance) --> mechanical stimuli
Thermoreception --> heat stimuli
Nociception --> Mechanical, Heat, Chemical |
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Term
| Factors contributing to response of sensory receptor cell |
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Definition
1. Receptive Field
2. Stimulus Quality
-homunculus
3. Strength of Stimulus
-sensory recceptor cells have a threshold - stimulus must be of some minimal value for it to be detected |
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Term
| Thalamic Nuclei Corticies |
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Definition
Somatosensory Cortex --> Parietal Lobe
Visual Cortex --> Occipital Lobe
Auditory Cortex --> Temporal Lobe
Olfactory cortex --> Frontal Lobe
Insula (Gustatory Cortex) --> Temporal Lobe |
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Term
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Definition
- AMPA (or quisqualate) applied to a cell for long enough, the channel desensitizes
- then subsequent application of kainate --> no rxn
- kainate reactivates the receptor
- KA doesn't desensitize
- AMPA desensitizes |
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Term
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Definition
Hoshi Zagotta Aldrich
- test ball & chain hypothesis by making synthetic balls and chucking them at the channel
- apply ball internally works (externally, no inactivation)
- confirmed by: proteolytic enzyme
- synthetic peptides with same sequence as ball region & put them at the chain |
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Term
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Definition
- heteromeric channels
- only one subunit is necessary to gate the channel
- inactivation rate is proportional to the number of subunits with gates but only one is active at a time |
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Term
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Definition
- deletion of 2 AA's causes a K channel to become non-selective for cations & can be blocked by dications (ie Mg++)
- positively charged AA needed for cationic block |
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Term
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Definition
- non-NMDA (AMPA) channels are made out of three subunits GluR1, 2, 3, and only combinations of 1 and 3 elicit nice Ca currents
- 2 seems to be inhibitory. |
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Term
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Definition
- GluRB/GluR2 determines I-V relation; conductance simply increases with increasing voltage
- GluRA, GluRC, and GluRD have a neutral glutamine (Q) in TM2, GluRB has a positive arginine (R)
- arginine in TM2 dominates I-V relation of heteromeric channels. |
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Term
| Agonists of Glutamate Receptors |
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Definition
- AMPA
- Kainate
- NMDA (binding assays + electrophysiological activities showed this was a diff receptor) |
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Term
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Definition
- desensitize to KA & Glu
- no response to AMPA |
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Term
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Definition
- desensitize to AMPA & Glu
- no desensitization to KA
- antagonist: CNQX
- flip & flop -- alternatively spliced regions (between TM3 & TM4)
- flip & flop differ in rate and extent of desensitization which eventually effects APs |
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