Term
| Name Cascade that occurs when norepinephrine binds to a B-Adrenergic receptor |
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Definition
| First Norepinephrine binds to the receptor. This binding causes the GDP---GTP bound alpha subunit of the g protein and it dissociates. This GTP bound alpha subunit that attaches to adenylyl cyclase. This protein is responsible for changing AMP into cyclic AMP. cAMP then activates protein kinases such as protein kinase A. THis protein kinase A then phosphorylates substrate proteins and opens Ca channels in the heart. |
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Term
| Cascade when Glutamate plugs into mGluR receptor |
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Definition
| Glutamate plugs into mGluR which causes the active GTP bound alpha subunit of the g protein to dissociate. This alpha subunit then activates phospholipase C which activates DIG and IP3. IP3 induces Ca release. DIG activates protein kinase C. Both Ca release and protein kinase C increase protein phosphorylation and calcium binding proteins. |
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Term
| 3 types of temporal memory |
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Definition
1. Short term memory (fractions of seconds- seconds)
2. working memory (seconds-minutes)
3. long term memory ( days- years) |
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Term
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Definition
Implicit and Explicit memory
Explicit: declarative (events and facts) in the medial temporal lobe
Implicit (non declarative)
-operant and classical conditioning (amygdala and cerebellum)
-priming (neocortex)
-procedural (striatum)
-nonassociation learning, habituation, and sensitization (reflex pathways) |
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Term
| Proof that hippocampus is related to memory |
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Definition
| 1. lesion hippocampus and do morris water maze task: rats with hippocamal lesions do not learn, unlike control rats who after 10 trials go straight to the platform. |
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Term
| Short term synaptic plasticity |
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Definition
| lasts from ms to secs. The main mechanism is by a change in NT release from the presynaptic cell. The terms are facilitation, potentiation, augmentation, and depression |
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Term
| Short term plasticity is calcium dependent |
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Definition
| if you use a calcium buffer you dont get short term potentiation. You get a strengthened post synaptic response by a change presynaptically. The change is not due to more calcium release but rather the rapid incoming stimuli. Calcium from the first stimulus is still in the presynaptic terminal because it takes alot longer to break down then it does to rush in during a stimulus. So the next stimulus that occurs when calcium is still around will cause a larger post synaptic response by releasing more NT (Ca binds synaptotagmin to facilitate exocytosis). Takes 40-50 seconds for calcium to be broken down int he presynaptic cell. |
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Term
| Aplyasia: Gill withdrawal reflex |
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Definition
| It is a very simple form of learning. If you continually stimulate the siphon of the aplysia, the aplysia will withdraw its gills. Eventually the stimulus response habituates and the aplysia will no longer withdraw its gills. This is believed to be a simple form of learning. But then if you pair the siphon touch with a tail shock the signal will be sensitized. This is because the tail shock modulatory interneuron synapses on the sensory neurons presynaptic terminal at the interneuron and the motor neuron. The serotonin released here makes glutamate more important. |
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Term
| Short Term Sensitization (aplysia) |
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Definition
| Short term sensitization can last up to an hour. In the aplyasia case, a tail shock is paired with a siphon touch. The tail shock causes the modulatory interneuron that synapses on sensory neuron presynaptic terminals that are connected to the interneuron and motor neuron for the gill withdrawal. Serotonin is released. It binds to the serotonin receptor activating G proteins that binds to adenylyl cyclase which activates cAMP. The cAMP then activates protein kinase A releasing the catalytic subunits that bind and close the potassium channels. This causes a longer depolarization, increased chance for an AP, and increases post- synaptic response. |
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Term
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Definition
| focuses around the formation of persistent PKA by activating CREB on the DNA that forms ubiquitin that breaks down the regulatory subgroups of PKA allowing it to be more active in phorphorylating/ closing down potassium channels. |
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Term
| Explicit memory formation: hippocampal model system in vertebrates |
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Definition
| the afferent pathway comes into the dentate gyrus activating the granule cells. The granule cells axons project to the CA3 region and synapse on CA3 pyramidal cells whose axon called the schaffer colaterals project to the CA1 hippocampal pyramidal cells. |
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Term
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Definition
| cells that fire together, wire together. Essentially saying that if cell A depolarizes enough to fire cell B and cell A takes part enough times in the firing of cell B that eventually some kind of growth process occurs such that they are "wired" together. |
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Term
| Three key properties of LTP |
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Definition
1. cooperativity
2. selectivity
3. Associativity |
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Term
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Definition
| it is important that pre and post synaptic activity is paired in time, this leads to LTP |
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Term
| possible pre and post synaptic mechanisms |
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Definition
presynaptic: enhance NT release
Post synaptic:
-increase the number of AMPA receptors
-increase the responsiveness of AMPA receptors
-unmask silent synapses
- increase post synaptic excitability |
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Term
| AMPA receptor functional changes (responsiveness) |
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Definition
| Phosphorylation of the AMPA receptor makes it more responsive to glutamate. Phosphorylation increases the single channel conductance and it also increases the probability that the AMPA receptor will be open in the same glutamate concentration. |
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Term
| how is AMPA phosphorylated? |
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Definition
| NMDAr calcium comes in and activates CAMKII which then phosphorylates the AMPA receptors and causes them to bind to the membrane. |
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Term
| Silent Synapses (unmasking) |
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Definition
| Silent synapses have NMDA receptors but not AMPA receptors. Because NMDA receptors require both glutamate and depolarization to open, they cannot open easily without AMPA receptors. THe way that these synapses become active is by the depolarization of nearby cell (assocation) that depolarizes the silent synapse enough to remove the magnesium block on the NMDA receptors. |
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Term
| Down regulation of SK channels: post synaptic mechanisms |
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Definition
| SK channels are voltage independent calcium activated channels. After LTP induction SK channels are internalized. |
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Term
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Definition
| protein kinases regulate transcription factor activity and new proteins are needed for long term structural changes. Protein kinase A activates CREB to make the transcriptional regulators and synapse growth proteins. |
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Term
| LTP, protein synthesis and learning |
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Definition
| if decrease or block protein synthesis there is no LTP, also if you have an NMDA knock out mice they couldnt do morris water maze as well. |
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Term
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Definition
activity dependent
calcium dependent
NMDA dependent |
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Term
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Definition
| requires continuous low intensity stimulation (1 HZ for 15 min). These cells are stimulated by the climbing fiber and the parallel fiber. The climbing fiber stimulates a voltage gated calcium channel on the post synaptic membrane to increase calcium. THe majority goes on to create phosphotases. In higher affinity lower activity phosphotases dominate |
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Term
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Definition
| doesnt involve the NMDA receptor mGluR activates phosphlipase C which activates DAG and PIP which then activates PKC and IP3 respectively. |
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Term
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Definition
| stimulus--signal transduction--goes to CNS via spinal cord-- perception |
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Term
| four general stimulus properties are important for all sensory systems |
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Definition
1. modality
2. timing
3. intensity
4. location (of activated receptors) |
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Term
| Line labelling (modality coding) |
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Definition
| all sensory systems have their own sensory receptors and neurons that carry signals from their receptors to the CNS is a fashion parallel to other sensory systems. They do not share neurons or receptors. |
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Term
| 4 sub modalities of somatosensory system |
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Definition
1. discriminative touch (fine touch)
2. proprioception (where body is in space)
3. Temperature
4. pain (nociceptor)
Each sub modality has their own receptors and their own ascending neural pathway (labelled lines) |
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Term
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Definition
| psedounipolar cell in the PNS that recieves input from skin and muscle receptors that relays information to the spinal cord (CNS) |
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Term
| Dorsal Root ganglion pathways differ for mechanoreceptors and temperature and pain afferents |
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Definition
| The mechanoreceptor afferents go from (finger) to the DRG then project into the dorsal horn and ascend ipsilaterally and cross at the level of the medulla. On the other hand, temperature and pain afferents come into the DRG then dorsal horn where they immediately cross the midline into the ventral horn and ascend contralaterally. |
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Term
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Definition
are different areas of the body innvervated by particular spinal nerves.
Sacral: innervates butt and back of legs and feet
Lumbar: innervates from the hips down on the front
Thoracic: innnervates the trunk
Cervical: innervates the arms, shoulders, neck, and back of head
face is innervated by trigeminal nerve branches. |
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Term
| 4 types of mechanoreceptors |
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Definition
1. Merkel cells: found in the epidermis, have the best spatial resolution (smallest receptive field-sense the pattern in braille), they are slowly adapting.
2. Miessner corpuscles: are also located in the epidermis, but have larger receptive fields than merkel cells and are second most dense. They are rapidly adapting |
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Term
| Functional properties of each subtype of receptor |
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Definition
axon diameter
receptive field
timing of response to sensory stimuli |
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Term
| Axon diameter for different sensory neurons vary by submodality |
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Definition
1. proprioception (muscle spindles)
2. touch
3. pain temperature
4. pain temp and itch |
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Term
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Definition
merkel cells respond most specifically to the braille because they have the smallest receptive field and therefore the highest spatial resolution. The next best are the meissner corpuscle cells that respond to low frequency vibrations and have the next best spatial resolution.
The ruffinni endings do not show pattern at all because the finger is not changing in space much
The pacinian are constantly firing cuz they are sensitive to high frequency vibrations but have the largest receptive field so not very specific. |
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Term
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Definition
| at what distance can you not discern two points from one point? depends on the receptive field of your different cells. The fingers have the highest density of receptors thus they have the smallest receptive field and smallest two point discrimination, as opposed to your calf. |
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Term
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Definition
1. Receptive field
2. density of receptors |
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Term
| Timing: Slow to rapid adaptation |
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Definition
slowly adapting: merkel and ruffini
-you get AP firing during the entire stimulus that increases as pressure increases
Rapidly adapting: Meissner and pacinian cells that fire only during changing stimulus so during initiation and ending of stimulus. The slower the stimulus occurs (movement) the more firing/ longer the firing. |
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Term
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Definition
Meissner cells: are innervated by 1 or many DRG, they transduce information about low frequency vibrations, like textures moving across skin.
Pacinian cells: are innervated by one DRG neuron and they transduce information from high frequency stimulation like fast, deep pressure moving across skin |
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Term
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Definition
Merkel cells: are innervated by one or more DRG neurons and they give sensation of light pressure and are sensitive to curves, edges, and rough textures.
Ruffini endings are innervated by one DRG neuron and are sensitive to stretching skin by digit or limb movement. |
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Term
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Definition
1. muscle spindles: sense stretching of muscles
2. golgi tendon organs: total force applied to joint
3. joint receptors: joint placement in space |
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Term
| Ascending pathways for somatosensory inputs |
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Definition
touch and proprioceptive inputs come into the dorsal horn and ascend in the dorsal column medial lemniscal system on the ipsilateral side and cross at the midbrain.
Pain and temperature inputs synapse on neurons in the dorsal horn whose axons project across the midline into the ventral horn where they then ascend contralaterally. They ascend in the anteriolateral system. |
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Term
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Definition
| NT--receptor--g protein, effective protein--second messengers-- later effectors---target proteins |
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Term
| Somatic Sensory Components of the Thalamus |
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Definition
| Each of the several ascending somatic sensory pathways converge on the ventral posterior complex of the thalamus |
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Term
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Definition
laterally located ventral posterior lateral nucleus recieves projects from the medial lemniscus carrying somatosensroy info from the body and posterior head
VPM: ventral posterior medial nucleus of the thalamus recieves info from trigeminal lemniscus info from the face.
Info remains separated it its passage to cortical circuits. THe majority of axons from the ventral posterior complex project to layer 4 of the cortex |
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Term
| Primary somatosensory cortex |
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Definition
| is located in the postcentral gyrus of the parietal lobe and is comprised of four regions 3a,3b,1,2, Each section contains a separate and complete representation of the body: somatotopic maps (foot,leg, trunk, forelimbs, and face are represented medial to lateral arrangement) |
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