The hippocampal formation, as drawn by Santiago Ramon y Cajal. DG: dentate gyrus. Sub: subiculum. EC: entorhinal cortex. CA1-CA3: hippocampus proper
The hippocampal formation is a compound structure in the medial temporal lobe of the brain. There is no consensus concerning which brain regions are encompassed by the term, with some authors defining it as the dentate gyrus, the hippocampus proper and the subiculum;[1] and others including also the presubiculum, parasubiculum, and entorhinal cortex.[2] The hippocampal formation is thought to play a role in memory, spatial navigation and control of attention. The neural layout and pathways within the hippocampal formation are very similar in all mammals.[3]
Function[edit source | edit]
During the nineteenth and early twentieth centuries, based largely on the observation that, between species, the size of the olfactory bulb varies with the size of the parahippocampal gyrus, the hippocampal formation was thought to be part of the olfactory system.[4]
In 1937 Papez theorized that a circuit including the hippocampal formation constitutes the neural substrate of emotional behavior,[5] and Klüver and Bucy reported that, in monkeys, resection involving the hippocampal formation and the amygdaloid complex has a profound effect on emotional responses.[6][7] As a consequence of these publications, the idea that the hippocampal formation is entirely dedicated to olfaction began to recede.[8] (Today there is little support for the idea that the hippocampal formation is directly involved in emotion.)
Medial surface of the human cerebral cortex
In an influential 1947 review, Alf Brodal pointed out that mammal species thought to have no sense of smell nevertheless have fully intact hippocampal formations, that removal of the hippocampal formation did not affect the ability of dogs to perform tasks dependent on olfaction, and that no fibers were actually known that carry information directly from the olfactory bulb to any part of the hippocampal formation.[9] Though massive direct input from the olfactory bulb to the entorhinal cortex has subsequently been found,[10] the current view is that the hippocampal formation is not an integral part of the olfactory system.[11]
In 1900, the Russian neurologist Vladimir Bekhterev described two patients with a significant memory deficit who, on autopsy, were found to have softening of hippocampal and adjacent cortical tissue;[12] and, in 1957, Scoville and Milner reported memory loss in a series of patients subsequent to their removal of the patients' medial temporal lobes.[13] Thanks to these observations and a great deal of subsequent research, it is now broadly accepted that the hippocampal formation plays a role in some aspects of memory.[11]
EEG evidence from 1938 to the present, stimulation evidence from the 1950s, and modern imaging techniques together suggest a role for some part of the hippocampal formation (in concert with the anterior cingulate cortex) in the control of attention.[11]
In 1971, John O'Keefe and his student Jonathan Dostrovsky discovered neurons in the rat hippocampus that appeared to show activity related to the rat's location within its environment.[14] Despite skepticism from other investigators, O'Keefe and his co-workers, including Lynn Nadel, continued to investigate this question, in a line of work that eventually led to their very influential 1978 book The Hippocampus as a Cognitive Map.[15] As with the memory theory, there is now almost universal agreement that the hippocampal formation plays an important role in spatial coding, but the details are widely debated.[16]
References[edit source | edit]
- ^ Martin, JH (2003). "Lymbic system and cerebral circuits for emotions, learning, and memory". Neuroanatomy: text and atlas (third ed.). McGraw-Hill Companies. p. 382. ISBN 0-07-121237-X.
- ^ Amaral, D; Lavenex, P (2007). "Hippocampal neuroanatomy". In Anderson, P; Morris, R; Amaral, D; Bliss, T; I'Keefe. The hippocampus book (first ed.). New York: Oxford University Press. p. 37. ISBN 9780195100273.
- ^ Anderson, P; Morris, R; Amaral, D; Bliss, T; O'Keefe, J (2007). "The hippocampal formation". In Anderson, P; Morris, R; Amaral, D; Bliss, T; I'Keefe. The hippocampus book (first ed.). New York: Oxford University Press. p. 3. ISBN 9780195100273.
- ^ Finger, S (2001). "Defining and controlling the circuits of emotion". Origins of neuroscience: a history of explorations into brain function. Oxford/NewYork: Oxford University Press. p. 286. ISBN 0-19-506503-4.
- ^ Papez, JW (1937). "A proposed mechanism of emotion". Archives of neurology and psychiatry 38: 725–43.
- ^ Klüver, H; Bucy, PC (1937). ""Psychic blindness" and other symptoms following bilateral temporal lobectomy in Rhesus monkeys". American Journal of Physiology 119: 352–53.
- ^ Klüver, H; Bucy, PC (1939). "Preliminary analysis of functions of the temporal lobes in monkeys". Archives of Neurology and psychiatry 42: 979–1000.
- ^ Nieuwenhuys, R; Voogd, J; van Huijzen, C (2008). "The greater limbic system". The human central nervous system (fourth ed.). Berlin/Heidelberg/New York: Springer-Verlag. p. 917. ISBN 3-540-13441-7.
- ^ Brodal, A (1947). "Hippocampus and the sense of smell". Brain 70 (Pt 2): 179–222. doi:10.1093/brain/70.2.179. PMID 20261820.
- ^ Shipley, MT; Adamek, GD (1984). "The connections of the mouse olfactory bulb: a study using orthograde and retrograde transport of wheatgerm agglutinin conjugated to horsradish peroxidase". Brain Research Bulletin 12 (6): 669–688. doi:10.1016/0361-9230(84)90148-5. PMID 6206930.
- ^ a b c Anderson, P; Morris, R; Amaral, D; Bliss, T; O'Keefe, J (2007). "Historical perspective: Proposed functions, biological characteristics, and neurobiological models of the hippocampus". In Anderson, P; Morris, R; Amaral, D; Bliss, T; I'Keefe. The hippocampus book (first ed.). New York: Oxford University Press. pp. 9–36. ISBN 9780195100273.
- ^ Bekhterev, V (1900). "Demonstration eines gehirns mit zerstörung der vorderen und inneren theile der hirnrinde beider schläfenlappen". Neurologische Zeitenblatte 19: 990–991.
- ^ Scoville, WB; Milner B (1957). "Loss of Recent Memory After Bilateral Hippocampal Lesions". Journal of neurology, neurosurgery and psychiatry 20 (1): 11–21. doi:10.1136/jnnp.20.1.11. PMC 497229. PMID 13406589.
- ^ O'Keefe J, Dostrovsky J (1971). "The hippocampus as a spatial map. Preliminary evidence from unit activity in the freely-moving rat". Brain Res 34 (1): 171–75. doi:10.1016/0006-8993(71)90358-1. PMID 5124915.
- ^ O'Keefe, J; Nadel L (1978). The Hippocampus as a Cognitive Map. Oxford University Press. ISBN 0-19-857206-9.
- ^ Moser, EI; Moser M-B (1998). "Functional differentiation in the hippocampus". Hippocampus 8 (6): 608–19. doi:10.1002/(SICI)1098-1063(1998)8:6<608::AID-HIPO3>3.0.CO;2-7. PMID 9882018.
External links[edit source | edit]
- Image University of Michigan Anatomy Project.
- Image University of California Davis Brain Atlas
Human brain: forebrain (cerebrum, cerebral cortex, cerebral hemispheres, grey matter) (TA A14.1.09.002–240, 301–320, GA 9.818–826)
|
|
Frontal lobe |
Superolateral |
Prefrontal |
- Superior frontal gyrus
- Middle frontal gyrus
- Inferior frontal gyrus: 11l
- 47-Pars orbitalis
- Broca's area
- 44-Pars opercularis
- 45-Pars triangularis
- Superior frontal sulcus
- Inferior frontal sulcus
|
|
Precentral |
- Precentral gyrus
- Precentral sulcus
|
|
|
Medial/inferior |
Prefrontal |
- Superior frontal gyrus
- Medial frontal gyrus
- Paraterminal gyrus/Paraolfactory area
- Straight gyrus
- Orbital gyri/Orbitofrontal cortex
- Ventromedial prefrontal cortex
- Subcallosal area
- Olfactory sulcus
- Orbital sulci
|
|
Precentral |
- Paracentral lobule
- Paracentral sulcus
|
|
|
Both |
- Primary motor cortex
- Premotor cortex
- Supplementary motor area
- Frontal eye fields
|
|
|
Parietal lobe |
Superolateral |
- Superior parietal lobule
- Inferior parietal lobule
- 40-Supramarginal gyrus
- 39-Angular gyrus
- Parietal operculum
|
|
Medial/inferior |
- Paracentral lobule
- Precuneus
Marginal sulcus
|
|
Both |
- Postcentral gyrus/primary somatosensory cortex
- Secondary somatosensory cortex
- Posterior parietal cortex
|
|
|
Occipital lobe |
Superolateral |
- Occipital pole of cerebrum
- Lateral occipital gyrus
- Lunate sulcus
- Transverse occipital sulcus
|
|
Medial/inferior |
- Primary visual cortex
- Cuneus
- Lingual gyrus
|
|
|
Temporal lobe |
Superolateral |
- Transverse temporal gyrus/Primary auditory cortex
- Superior temporal gyrus
- Middle temporal gyrus
- Inferior temporal gyrus
- Superior temporal sulcus
- Inferior temporal sulcus
|
|
Medial/inferior |
- Fusiform gyrus
- Medial temporal lobe
|
|
|
Interlobar
sulci/fissures |
Superolateral |
- Central (frontal+parietal)
- Lateral (frontal+parietal+temporal)
- Parieto-occipital
- Preoccipital notch
|
|
Medial/inferior |
- Medial longitudinal
- Cingulate (frontal+cingulate)
- Collateral (temporal+occipital)
- Callosal sulcus
|
|
|
Limbic lobe |
Parahippocampal gyrus |
- anterior
- Entorhinal cortex
- Perirhinal cortex
- Posterior parahippocampal gyrus
- Prepyriform area
|
|
Cingulate cortex/gyrus |
- Subgenual area
- Anterior cingulate
- Posterior cingulate
- Isthmus of cingulate gyrus: Retrosplenial cortex
|
|
Hippocampal formation |
- Hippocampal sulcus
- Fimbria of hippocampus
- Dentate gyrus
- Rhinal sulcus
|
|
Other |
- Supracallosal gyrus
- Uncus
|
|
|
Insular lobe |
- Long gyrus of insula
- Short gyri of insula
- Circular sulcus of insula
|
|
General |
- Operculum
- Poles of cerebral hemispheres
|
|
Some categorizations are approximations, and some Brodmann areas span gyri.
|
anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp
|
noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr
|
proc, drug (N1A/2AB/C/3/4/7A/B/C/D)
|
|
|
|
Human brain, cerebrum, Interior of the cerebral hemispheres—Rostral Basal ganglia and associated structures (TA A14.1.09.321–552, GA 9.832–837)
|
|
Basal ganglia |
Grey matter
|
Corpus striatum
|
- striatum: Putamen
- Caudate nucleus
lentiform nucleus: Putamen
- Globus pallidus (GPe
- GPi)
|
|
Ventral striatum
|
- Nucleus accumbens
- Olfactory tubercle
- Islands of Calleja
|
|
Other
|
|
|
|
White matter
|
Internal capsule (Anterior limb
- Genu
- Posterior limb
- Optic radiation)
Corona radiata
- External capsule
- Extreme capsule
Pallidothalamic tracts: Thalamic fasciculus (Ansa lenticularis
- Lenticular fasciculus)
- Subthalamic fasciculus
|
|
|
Rhinencephalon |
Grey matter
|
- Anterior olfactory nucleus
- Anterior perforated substance
- Olfactory bulb
|
|
White matter
|
- Olfactory tract (Medial olfactory stria
- Lateral olfactory stria)
- Olfactory trigone
|
|
|
Other basal forebrain |
Grey matter
|
- Substantia innominata (Basal optic nucleus of Meynert)
- Nucleus of diagonal band
|
|
White matter
|
- Diagonal band of Broca
- Stria terminalis
|
|
|
Archicortex:
Hippocampal formation/
Hippocampus anatomy |
Grey matter
|
- Hippocampus proper: CA1
- CA2
- CA3
- CA4
Dentate gyrus: Fascia dentata
Subiculum
|
|
White matter
|
- Alveus
- Fimbria
- Perforant path
- Schaffer collateral
|
|
|
|
anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp
|
noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr
|
proc, drug (N1A/2AB/C/3/4/7A/B/C/D)
|
|
|
|
Sensory system: Olfactory system / Olfaction / Rhinencephalon (TA 15.1, GA 10.992)
|
|
Olfactory epithelium |
Olfactory glands · Olfactory mucosa · Sustentacular cell
|
|
Olfactory nerve: 1° neuron |
Olfactory receptor neurons (Olfactory receptor) → Olfactory bulb (Glomeruli)
|
|
Olfactory nerve: 2° neuron |
Mitral cells → Olfactory tract → Olfactory trigone
|
|
Lateral olfactory stria/
Primary olfactory cortex |
Piriform cortex · EC-hippocampus system (Entorhinal cortex, Hippocampal formation) · Prepyriform area · Periamygdaloid cortex
Stria medullaris → Habenular nuclei
Amygdala → Stria terminalis → Hypothalamus
Medial forebrain bundle → Hypothalamus
|
|
Medial olfactory stria |
Anterior olfactory nucleus
|
|
|
|