Retrosplenial cortex

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Retrosplenial cortex

?

Medial surface of the brain with Brodmann's areas numbered.

Details

Identifiers

Latin

Regio retrosplenialis

NeuroNames

2436,?1802

Anatomical terms of neuroanatomy

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The?retrosplenial cortex?(RSC) is a?cortical area?in the brain comprising?Brodmann areas 29?and?30.[1]?It is secondary association cortex, making connections with numerous other brain regions. The region's name refers to its anatomical location immediately behind the?splenium?of the?corpus callosum?in primates, although in rodents it is located more towards the brain surface and is relatively larger. Its function is currently not well understood, but its location close to visual areas and also to the hippocampal spatial/memory system suggest it may have a role in mediating between perceptual and memory functions,[2]?particularly in the spatial domain.[3]?However, its exact contribution to either space or memory processing has been hard to pin down.[4]

Contents

·?1Anatomy

·?2Neurophysiology

·?3Function

·?4Pathology

·?5Gallery

·?6References

Anatomy[edit]

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This section?needs expansion. You can help by?adding to it.(November 2014)

There is large variation in the region's size across different species. In humans it comprises roughly 0.3% of the entire cortical surface whereas in rabbits it is at least 10%[5]?and in rats it extends for more than half the cerebrum dorso-ventrally, making it one of the largest cortical regions.[2]

On the basis of its microscopic cellular structure it is divided into dysgranular (area 30) and granular (area 29) regions.[1]?It has dense reciprocal projections with the visual cortex, postsubiculum (also known as dorsal?presubiculum) and with?anterior thalamic nuclei?and the?hippocampus.[6]

Neurophysiology[edit]

Neurophysiological studies of retrosplenial cortex have mainly been done in rats. Early work showed that around 8.5% of neurons in the retrosplenial cortex are?head direction cells?while other neurons have correlated with movement parameters such as spatial location and running speed.[7][8]?Recent studies have shown that retrosplenial neuronal activity reflects multiple parameters simultaneously including which environment the animal is currently in,[9]?its spatial position in the environment,[10][9]?its current head direction and running speed,[9]?as well as whether the animal is turning[10]?or plans to turn in the future.[11]?Many of these features of retrosplenial neurophysiology develop slowly as the animal learns to navigate within an environment,[11]?consistent with the idea that the retrosplenial cortex participates in the long-term storage of spatial memory.[12]

Function[edit]

In humans,?fMRI?studies implicate the retrosplenial cortex in a wide range of cognitive functions including?episodic memory, navigation, imagining future events and processing scenes more generally.[2][13]?Rodent studies?suggest the region is important for using surrounding visual cues to carry out these tasks.[12][14][15][16]?Retrosplenial cortex is particularly responsive to permanent, non-moving environmental landmarks[17][18]?and is also implicated in using them to make spatial judgements.[19][20]

(可能這里的permanent, non-moving environmental landmarks指的是對某事物的絕對信任，比如前面懸崖上的一塊石頭，我如果信任它穩(wěn)定的話我就會敢于站上面，甚至蹦跳，這種感覺應(yīng)該就是dorsal visual stream視覺信息通過retrosplenial cortex來實現(xiàn)的吧，應(yīng)該是起到激發(fā)serotonin降低NE的作用，所謂的十分的信任那種感覺，也就是retrosplenial cortex的興奮可以提高serotonin濃度？。但是如果，NE濃度過高，NE很容被放大，那就是不信任而慌亂的結(jié)果。而且retrosplenial cortex是在NE濃度容易被激發(fā)的環(huán)境中被興奮才會起到很好的作用，恐高的人恐怕就是沒有及時激發(fā)retrosplenial cortex吧？retrosplenial cortex好像是第一個能夠提高serotonin濃度的皮層，那么能對“信任”記憶強化的遞質(zhì)只有acetylcholine，那就是nucleus basalis，也就是那種厚重、深深的信任感源自于serotonin濃度高與nucleus basalis對retrosplenial cortex的強烈影響，從而通過acetylcholine強化了皮層-anterior thalamus之間的連接關(guān)系。因此，當(dāng)nucleus basalis萎縮時，retrosplenial cortex與anterior thalamus形成的記憶關(guān)系最先消失，那些形成篤定記憶的能力最先消失?；蛟Sretrosplenial cortex是真實宮殿記憶模式中的那個框架？)

It has also been suggested that retrosplenial cortex may translate between egocentric (self-centred)?and allocentric (world-centred)?spatial information, based upon its anatomical location between the?hippocampus?(where there are allocentric?place cell?representations) and the?parietal lobe?(which integrates egocentric sensory information).[12][21][22]

Competitors in the?World Memory Championships?are able to perform outstanding feats of memory and show increased?fMRI?activation in their retrosplenial cortex than normal controls when doing so.[23]?This is thought to be due to their use of a spatial learning strategy or?mnemonic?device known as the?method of loci.

The region also displays slow-wave?theta rhythmicity[24]?and when people retrieve?autobiographical memories, there is theta band interaction between the retrosplenial cortex and the medial?temporal lobe.[25]

Pathology[edit]

The retrosplenial cortex is one of several brain areas that produces both an?anterograde?and?retrograde?amnesia when damaged.[26]?People with lesions involving the retrosplenial cortex also display a form of?topographical disorientation?whereby they can recognise and identify environmental landmarks, but are unable to use them to orientate themselves.[2]

The retrosplenial cortex is one of the first regions to undergo pathological changes in?Alzheimer's disease?and its?prodromal?phase of?mild cognitive impairment.[27][28][29]?There are also experimental findings showing that layer 5 of the retrosplenial cortex is likely responsible for dissociative states of consciousness in mammals.[30]