Neuron / Synapse continued, Asymmetric synapse density table, turnover, Synapse Asymmetric vs Symmetric, Postsynaptic density, Cranial nerve
Neuron
- Spine (= ‘dendritic spine’): dendrite (= ‘dendritic shaft’) 에서 삐죽 나온 것
A: neuron with dendritic spines diagram. Labels: dendrite, dendritic spines, synapse, presynaptic axon.
B: synaptic cross-section diagram. Labels: presynaptic terminal, mitochondria, Ca²⁺ channel, synaptic vesicle, NT receptors, NTs → synaptic cleft, postsynaptic density (PSD), postsynaptic spine.
Spiny dendrite of a striatal medium spiny neuron (electron micrograph, 1 μm scale). Labels: Dendrite, Spine neck, Spine head.
Spine cartoon labels: presynaptic bouton, axon, postsynaptic spine, spine head, spine neck, dendrite.
Common types of dendritic spines
- thin
- mushroom
- stubby
Asymmetric synapse density
| normal density | reduced density | increased density |
|---|---|---|
| normal | PD | Cell therapy |
| [mainly Axo-spinous contact] Dopaminergic terminals in the normal striatum predominantly synapse onto the neck, and glutamatergic endings onto the head, of dendritic spines (Freund et al., 1984; Groves, 1980). | Dopamine depletion leads to a significant loss of dendritic spines |
- ↓ axo-spinous contact, ↑ axo-dendrite contact in the striatum - ↑ asymmetric synapses onto TH+ grafted cells in the striatum (원래 NS synapse in the striatum 은 dopaminergic, symmetric, excitatory 인데, 병리적으로 glutamatergic, asymmetric, excitatory 으로 바뀌어서 dyskinesia 유발하는 것 아닌가 (Soderstrom et al. 2008, PMID)) - non-TH+, asymmetric, perforated synapses |
turnover
- The median turnover rate of neurons within the renewing subpopulation is 1.75%/year during adulthood, corresponding to approximately 700 new neurons/day or 0.004% of the dentate gyrus neurons/day in the human hippocampus.
Synapse
| Asymmetric Gray's Type I | Symmetric Gray's Type II | |
|---|---|---|
| Presynaptic vesicle | rounded vesicles in the presynaptic cell, and | flattened or elongated vesicles, and |
| Postsynaptic density | a prominent postsynaptic density | do not contain a prominent postsynaptic density. |
| Function | excitatory | Inhibitory |
| Synaptic cleft | Narrower than asymmetric | |
| (proportion) | 80% of the total population of synapses | less |
| membrane differentiations | (a) Asymmetrical membrane differentiations Copyright © 2007 Wolters Kluwer Health | (b) Symmetrical membrane differentiations Lippincott Williams & Wilkins |
| Nigrostriatal pathway | Striatal dopaminergic terminals predominantly make symmetric, but rarely asymmetric synapses (Freund et al., 1984). (보통과 반대네!) |
Postsynaptic density
- Location
- 위의 그림에서 면도한 부분처럼 거뭇거뭇한 부분, attached to the postsynaptic membrane
- Size
- 250 to 500 nanometres in diameter and 25 to 50 nanometres in thickness
- During synaptic plasticity, the total size of the PSD is increasing along with an increase in synaptic size and strength after inducing long-term potentiation at single synapses.[1]
- Composition
- postsynaptic density-95 (PSD95), neuroligin (a cellular adhesion molecule), NMDA receptors, AMPA receptors, calcium/calmodulin-dependent protein kinase II and actin. cell adhesion molecules and a diverse set of other signaling proteins
- Function
- concentrate and organize neurotransmitter receptors
- signaling apparatus
- instance kinases and phosphatases in the PSD are activated and released from the PSD to change the activity of proteins located in the spine or are transported to the nucleus to affect protein synthesis
Electrical synapse
distinct minority, compared to the chemical synapse
- structure
- gap junction : narrower than the synaptic cleft
Cranial nerve
With the exception of the olfactory nerve (I) and optic nerve (II), all the nuclei are present in the brainstem.[3]
The olfactory nerve (I) emerges from the olfactory bulb,
the optic nerve (II) is deemed to emerge from the lateral geniculate nuclei.[10]
The brainstem, with cranial nerve nuclei and tracts shown in red.
Location[edit] — Nuclei of the cranial nerves
| Cranial nerve | Nuclei |
|---|---|
| Olfactory nerve | Olfactory bulb |
| Optic nerve | Lateral geniculate nucleus |
| Oculomotor nerve | Oculomotor nucleus Edinger-Westphal nucleus |
| Trochlear nerve | Trochlear nucleus |
| Trigeminal nerve | Trigeminal nerve nuclei: Mesencephalic nucleus Principal sensory nucleus Spinal trigeminal nucleus Trigeminal motor nucleus |
| Abducens nerve | Abducens nucleus |
| Facial nerve | Facial motor nucleus Superior salivatory nucleus Solitary nucleus |
| Vestibulocochlear nerve | Vestibular nuclei w. subnuclei Cochlear nucleus w. subnuclei |
| Glossopharyngeal nerve | Solitary nucleus Spinal nucleus of the trigeminal nerve Lateral nucleus of vagal trigone. Nucleus ambiguus Inferior salivatory nucleus |
| Vagus nerve | Dorsal nucleus of vagus nerve Nucleus ambiguus Solitary nucleus Spinal trigeminal nucleus |