322:
mossy cells in the CA4 of
Lorente de NĂł did not have schaffer collaterals and that, in contrast to pyramidal cells, they project to the inner molecular layer of the DG and not to CA1. The same author thus concluded that the term CA4 should be abandoned and that the zone should be regarded as the polymorphic layer of the dentate gyrus (the area dentata of Blackstad (1956)). The polymorphic layer is often called the hilus or hilar region. The neurons in the polymorphic layer, including mossy cells and GABAergic interneurons, primarily receive inputs from the granule cells in the dentate gyrus in the form of mossy fibers and project to the inner molecular layer of the dentate gyrus via the associational/commissural projection. They also receive a small number of connections from pyramidal cells in CA3. They, in turn, project back into the dentate gyrus at distant septotemporal levels.
286:
overall, has been considered to be the “pacemaker” of the hippocampus. Much of the synchronous bursting activity associated with interictal epileptiform activity appears to be generated in CA3. Its excitatory collateral connectivity seems to be mostly responsible for this. CA3 uniquely, has pyramidal cell axon collaterals that ramify extensively with local regions and make excitatory contacts with them. CA3 has been implicated in a number of working theories on memory and hippocampal learning processes. Slow oscillatory rhythms (theta-band; 3–8 Hz) are cholinergically driven patterns that depend on coupling of interneurons and pyramidal cell axons via gap junctions, as well as glutaminergic (excitatory) and GABAergic (inhibitory) synapses. Sharp EEG waves seen here are also implicated in memory consolidation.
334:
57:
294:) of these cells tend to coincide with the peaks of the superimposed gamma oscillation. Approximately a decade later, the existence of well-defined CA3 sequences has experimentally been shown in the laboratory of Loren Frank, moreover these results demonstrated that previously encoded sequential experience can be replayed by the CA3 region during episodes called "awake replay". A recent hypothesis postulates that CA3 sequences are built up pair by pair during
350:
42:
282:. There are also a significant number of recurrent connections that terminate in CA3. Both the recurrent connections and the Schaffer collaterals terminate preferentially in the septal area in a dorsal direction from the originating cells. CA3 also sends a small set of output fibers to the lateral septum.
289:
A key physiological function of the CA3 is encoding heteroassociative memories using its recurrent circuitry. A seminal hypothesis by John Lisman postulated that during a single theta cycle, a defined set of CA3 principal neurons can activate each other to form a well defined sequence, and the spikes
321:
is a misleading term introduced by
Lorente de NĂł. He observed that the pyramidal layer of the CA3 was continuous with polymorphic layer of the dentate gyrus and that the "modified pyramids" (later known as mossy cells) had Schaffer collaterals similar to CA3 pyramidal cells. Amaral showed that the
285:
The region is conventionally divided into three divisions. CA3a is the part of the cell band that is most distant from the dentate (and closest to CA1). CA3b is the middle part of the band nearest to the fimbria and fornix connection. CA3c is nearest to the dentate, inserting into the hilus. CA3
831:
270:
or thorn, only found in CA3 pyramidal cells and hilar mossy cells. The thorn has a thin single spine with a number of heads. Clusters of thorns sit on a dendrite on a broad stem. There are also longer spines called
333:
824:
817:
417:
Tsamis, IK; Mytilinaios, GD; Njau, NS; Fotiou, FD; Glaftsi, S; Costa, V; Baloyannis, JS (February 2010). "Properties of CA3 dendritic excrescences in
Alzheimer's disease".
130:
666:
Bains JS, Longacher JM, Staley KJ (August 1999). "Reciprocal interactions between CA3 network activity and strength of recurrent collateral synapses".
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461:
Jensen O, Lisman JE (September 1996). "Hippocampal CA3 region predicts memory sequences: accounting for the phase precession of place cells".
106:
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Lisman JE (February 1999). "Relating hippocampal circuitry to function: recall of memory sequences by reciprocal dentate-CA3 interactions".
61:
Basic circuit of the hippocampus, shown using a modified drawing by Ramon y Cajal. DG: dentate gyrus. Sub: subiculum. EC: entorhinal cortex
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Jerome Engel TAP, ed. Epilepsy: A Comprehensive
Textbook in Three Volumes. Philadelphia, PA: Lippincott Williams & Wilkins; 2008
278:
The pyramidal cells in CA3 send some axons back to the dentate gyrus hilus, but they mostly project to regions CA2 and CA1 via the
137:
374:
Lauer, M; Senitz, D (October 2006). "Dendritic excrescences seem to characterize hippocampal CA3 pyramidal neurons in humans".
704:
Lorente de NĂł, R (1934). "Studies on the structure of the cerebral cortex. Continuation of the study of the ammonic system".
255:. The perforant path passes through the stratum lacunosum and ends in the stratum moleculare. There are also inputs from the
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is a small region located between CA1 and CA3. It receives some input from layer II of the entorhinal cortex via the
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Carr MF, Karlsson MP, Frank LM (August 2012). "Transient slow gamma synchrony underlies hippocampal memory replay".
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which terminate in the stratum radiatum, along with commisural connections from the other side of the hippocampus.
240:
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251:, and also from cells in the entorhinal cortex via the perforant path. The mossy fiber pathway ends in the
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is the first region in the hippocampal circuit, from which a major output pathway goes to layer V of the
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617:"Episodic Memories: How do the Hippocampus and the Entorhinal Ring Attractors Cooperate to Create Them?"
162:
which is made up of four regions or subfields. The subfields CA1, CA2, CA3, and CA4 use the initials of
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Amaral, DG (1978). "A Golgi study of cell types in the hilar region of the hippocampus in the rat".
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are more like those in CA3 than those in CA1. It is often ignored due to its small size.
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The pyramidal cells in CA3 have a unique type of dendritic spine called a
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of the CA3 population that form a complete matrix of connections.
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302:. This mechanism is based on the synapses of the CA3 recurrent
275:. These unique structures also help to demarcate CA3 from CA2.
777:. In Anderson P, Morris R, Amaral, Bliss T, O'Keefe J (eds.).
298:, relying on precisely timed, phase-precessing input from the
773:
Anderson P, Morris R, Amaral, Bliss T, O'Keefe J (2007).
533:"Awake replay of remote experiences in the hippocampus"
781:(first ed.). New York: Oxford University Press.
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182:, regions in the hippocampus proper which form a
355:Diagram of hippocampal regions in a rat brain.
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46:Hippocampus location and regions in a human,
8:
339:High resolution micrograph of human brain,
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205:. Another significant output is to the
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7:
531:Karlsson MP, Frank LM (July 2009).
83:hippocampus proprius, cornu Ammonis
25:
1400:Anterior limb of internal capsule
621:Frontiers in Systems Neuroscience
348:
332:
138:Anatomical terms of neuroanatomy
795:from the original on 2020-03-15
376:Journal of Neural Transmission
1:
1088:Anterior perforated substance
510:10.1016/s0896-6273(00)81085-5
615:Kovács KA (September 2020).
160:structure of the hippocampus
27:Part of the brain of mammals
1381:Anterior nuclei of thalamus
775:"The hippocampal formation"
1482:
1083:Anterior olfactory nucleus
431:10.2174/156720510790274482
419:Current Alzheimer Research
848:and associated structures
634:10.3389/fnsys.2020.559186
388:10.1007/s00702-005-0428-8
166:, an earlier name of the
136:
54:
39:
1172:Nucleus of diagonal band
343:through the hippocampus.
239:receives input from the
1121:Lateral olfactory stria
1377:Mammillothalamic tract
1190:Diagonal band of Broca
1116:Medial olfactory stria
1052:Subthalamic fasciculus
1030:Pallidothalamic tracts
261:diagonal band of Broca
1428:Hippocampal formation
1412:Parahippocampal gyrus
1214:Hippocampal formation
1160:Substantia innominata
1045:Lenticular fasciculus
744:10.1002/cne.901820508
180:hippocampal subfields
158:refers to the actual
18:Hippocampal subfields
779:The hippocampus book
475:10.1101/lm.3.2-3.279
280:Schaffer collaterals
1466:Hippocampus (brain)
1308:Schaffer collateral
1219:Hippocampus anatomy
1035:Thalamic fasciculus
668:Nature Neiroscience
537:Nature Neuroscience
463:Learning and Memory
306:corraterals on the
188:trisynaptic circuit
1236:Hippocampus proper
910:Olfactory tubercle
706:J. Psychol. Neurol
268:thorny excrescence
156:hippocampus proper
35:Hippocampus proper
1453:
1452:
1416:Entorhinal cortex
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1319:
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1136:
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1128:Olfactory trigone
1060:
1059:
1040:Ansa lenticularis
974:Centrum semiovale
960:
959:
905:Nucleus accumbens
326:Additional images
300:entorhinal cortex
292:action potentials
203:entorhinal cortex
152:
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16:(Redirected from
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1195:Stria terminalis
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1017:External capsule
981:Internal capsule
900:Ventral striatum
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144:edit on Wikidata
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1404:Cingulate gyrus
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1373:Mammillary body
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1165:Nucleus basalis
1143:basal forebrain
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1111:Olfactory tract
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1022:Extreme capsule
1001:Optic radiation
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919:Globus pallidus
891:Caudate nucleus
881:Dorsal striatum
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382:(10): 1469–75.
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341:coronal section
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296:memory encoding
253:stratum lucidum
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226:pyramidal cells
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178:There are four
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1093:Olfactory bulb
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1066:Rhinencephalon
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788:978-0195100273
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738:(5): 851–914.
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1392:Telencephalon
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1263:Dentate gyrus
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855:Basal ganglia
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259:and from the
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257:medial septum
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249:dentate gyrus
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245:granule cells
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164:cornu Ammonis
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48:coronal plane
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30:
19:
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1365:Diencephalon
1285:White matter
1255:
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1245:
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1182:White matter
1103:White matter
1028:
966:White matter
797:. Retrieved
778:
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585:
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425:(1): 84–90.
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241:mossy fibers
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107:A14.1.09.327
82:
29:
1424:Hippocampus
1228:Grey matter
1209:Archicortex
1152:Grey matter
1075:Grey matter
864:Grey matter
846:human brain
186:called the
168:hippocampus
72:Identifiers
799:2016-12-15
712:: 113–177.
674:(8): 720.
588:(4): 700.
543:(7): 913.
504:(2): 233.
469:(2): 279.
361:References
90:NeuroNames
1440:Subiculum
1275:Subiculum
952:Claustrum
308:dendrites
207:subiculum
174:Structure
1460:Category
1408:Cingulum
947:Amygdala
873:Striatum
840:Rostral
793:Archived
760:44257239
688:10412061
653:33013334
602:22920260
567:19525943
518:10069330
483:10456097
439:20205674
404:21440177
396:16465457
1357:pathway
1298:Fimbria
886:Putamen
844:of the
644:7511719
558:2750914
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