Editing Spatial memory (section)

==Neuroplasticity==
{{see also|Neurobiological effects of physical exercise#Cognitive control and memory}}

Spatial memories are formed after an animal gathers and processes sensory information about its surroundings (especially [[Visual system|vision]] and [[proprioception]]). In general, mammals require a functioning hippocampus (particularly area CA1) in order to form and process memories about space. There is some evidence that human spatial memory is strongly tied to the right hemisphere of the brain.<ref>{{cite journal | last1 = Gutbrod | first1 = K | last2 = Cohen | first2 = R | last3 = Maier | first3 = T | last4 = Meier | first4 = E  | year = 1987 | title = Memory for spatial and temporal order in aphasics and right hemisphere damaged patients | journal = Cortex | volume = 23 | issue = 3| pages = 463–74 | pmid = 3677733 | doi=10.1016/s0010-9452(87)80007-2 | doi-access = free }}</ref><ref>{{cite journal | last1 = Nunn | first1 = JA | last2 = Graydon | first2 = FJ | last3 = Polkey | first3 = CE | last4 = Morris | first4 = RG  | year = 1999 | title = Differential spatial memory impairment after right temporal lobectomy demonstrated using temporal titration | journal = Brain | volume = 122 | issue = 1| pages = 47–59 | doi = 10.1093/brain/122.1.47 | pmid = 10050894 | doi-access = free }}</ref><ref>{{cite journal | last1 = Tucker | first1 = DM | last2 = Hartry-Speiser | first2 = A | last3 = McDougal | first3 = L | last4 = Luu | first4 = P | year = 1999 | title = Mood and spatial memory: emotion and right hemisphere contribution to spatial cognition | journal = Biol Psychol | volume = 50 | issue = 2| pages = 103–25 | doi = 10.1016/S0301-0511(99)00005-8 | pmid = 10403200 | last5 = Degrandpre | first5 = D }}</ref>

Spatial learning requires both [[NMDA receptor|NMDA]] and [[AMPA receptor|AMPA]] receptors, consolidation requires NMDA receptors, and the retrieval of spatial memories requires AMPA receptors.<ref>{{cite journal | last1 = Liang | first1 = KC | last2 = Hon | first2 = W | last3 = Tyan | first3 = YM | last4 = Liao | first4 = WL  | year = 1994 | title = Involvement of hippocampal NMDA and AMPA receptors in acquisition, formation and retrieval of spatial memory in the Morris water maze | journal = Chin J Physiol | volume = 37 | issue = 4| pages = 201–12 | pmid = 7796636 }}</ref> In rodents, spatial memory has been shown to covary with the size of a part of the hippocampal [[Mossy fiber (hippocampus)|mossy fiber]] projection.<ref>{{cite journal | last1 = Crusio | first1 = W. E. | last2 = Schwegler | first2 = H. | year = 2005 | title = Learning spatial orientation tasks in the radial-maze and structural variation in the hippocampus in inbred mice | journal = Behavioral and Brain Functions | volume = 1 | issue = 1| page = 3 | doi = 10.1186/1744-9081-1-3 | pmid=15916698 | pmc=1143776 | doi-access = free }}</ref>

The function of NMDA receptors varies according to the subregion of the hippocampus. NMDA receptors are required in the CA3 of the hippocampus when spatial information needs to be reorganized, while NMDA receptors in the CA1 are required in the acquisition and retrieval of memory after a delay, as well as in the formation of CA1 place fields.<ref>{{cite journal | last1 = Lee | first1 = I. | last2 = Kesner | first2 = R. P. | year = 2002 | title = Differential contribution of NMDA receptors in hippocampal subregions to spatial working memory | journal = Nature Neuroscience | volume = 5 | issue = 2| pages = 162–168 | doi = 10.1038/nn790 | pmid = 11780144 }}</ref> Blockade of the NMDA receptors prevents induction of [[long-term potentiation]] and impairs spatial learning.<ref>{{cite journal | last1 = Morris | first1 = R. G. M. | last2 = Anderson | first2 = E. | last3 = Lynch | first3 = G. S. | last4 = Baudry | first4 = M. | year = 1986 | title = Selective impairment of learning and blockade of long-term potentiation by an N-methyl-D-aspartate receptor anatagonist, AP5 | journal = Nature | volume = 319 | issue = 6056| pages = 774–776 | doi = 10.1038/319774a0 | pmid = 2869411 |bibcode = 1986Natur.319..774M }}</ref>

The CA3 of the hippocampus plays an especially important role in the encoding and retrieval of spatial memories. The CA3 is innervated by two afferent paths known as the perforant path (PPCA3) and the [[dentate gyrus]] (DG)-mediated mossy fibers (MFs). The first path is regarded as the retrieval index path while the second is concerned with encoding.<ref>{{cite journal | last1 = Lee | first1 = I. | last2 = Kesner | first2 = R. P. | year = 2004 | title = Encoding versus retrieval of spatial memory: Double dissociation between the dentate gyrus and the perforant path inputs into CA3 in the dorsal hippocampus | journal = Hippocampus | volume = 14 | issue = 1| pages = 66–76 | doi = 10.1002/hipo.10167 | pmid = 15058484 }}</ref>