wiki笔记--Projection fiber--2021/9/8

Projection fiber

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Projection fiber

Details

Identifiers

Latin

"Triple Cartridge Respirator" by T Doolen

 

Fibrae projectionis

NeuroNames

1218

TA98

A14.1.00.018

TA2

5617

FMA

76745

Anatomical terms of neuroanatomy

[edit on Wikidata]

The projection fibers consist of efferent and afferent fibers uniting the cortex with the lower parts of the brain and with the spinal cord. In human neuroanatomy, bundles of axons (nerve fibers) called tracts, within the brain, can be categorized by their function into association fibers, projection fibers, and commissural fibers.[1]

In the neocortex, projection neurons are excitatory neurons that send axons to distant brain targets.[2] Considering the six histologically-distinct layers of the neocortex, associative projection neurons extend axons within one cortical hemisphere; commissural projection neurons extend axons across the midline to the contralateral hemisphere; and corticofugal projection neurons extend axons away from cortex.

（这意味着同一小片皮层同时是associative projection、commissural projection、corticofugal projection。）

[2] That said, some neurons are multi-functional and can therefore be categorized into more than one such category.[2]

Contents

· 1Efferent

· 2Afferent

· 3References

· 4External links

Efferent[edit]

The principal efferent fibers are:

· (1) the motor tract, occupying the genu and anterior two-thirds of the occipital part of the internal capsule, and consisting of

o (a) the geniculate fibers, which decussate in the medulla, and end in the motor nuclei of the cranial nerves of the opposite side; and

o (b) the cerebrospinal fibers, which are prolonged through the medullary pyramids into the spinal cord:

· (2) the corticopontine fibers, ending in the pontine nuclei.

（这里意味着来自于大脑皮层的轴突能够直达pons。而在其他的词条我们会发现orbital cortex投射到midbrain和pons，而orbital cortex通过uncinate long association fiber与polar temporal cortex连接，而polar temporal cortex通过inferior longitudinal long association fiber与occipital cortex连接。上述连接意味着：视觉信息进入occipital cortex然后最终到达orbital cortex，从而直接影响midbrain和pons中核团的活动。这个机制对应着一类人的感觉，尤其是在视觉信息是静态状态时，这个感觉使得该信息突出于背景信息，一旦信息动起来，与背景信息相关联，这个感觉就没有了，因为你的注意力转移到其他的脑区功能，而不再维持上述通路。）

Afferent[edit]

The chief afferent fibers are:

· (1) those of the lemniscus which are not interrupted in the thalamus;

· (2) those of the superior cerebellar peduncle which are not interrupted in the red nucleus and thalamus;

· (3) numerous fibers arising within the thalamus, and passing through its stalks to the different parts of the cortex;

· (4) optic and acoustic fibers, the former passing to the occipital, the latter to the temporal lobe.