Angular gyrus
| Angular gyrus | |
|---|---|
 | |
 Drawing of a cast to illustrate the relations of the brain to the skull. (Angular gyrus labeled at upper left, in yellow section.) | |
| Details | |
| Identifiers | |
| Latin | gyrus angularis |
| NeuroNames | 109 |
| NeuroLexID | birnlex_1376 |
| TA98 | A14.1.09.124 |
| TA2 | 5472 |
| FMA | 61898 |
| Anatomical terms of neuroanatomy | |
Theangular gyrusis a region of thebrainlying mainly in the posteroinferior region of theparietal lobe,occupying the posterior part of theinferior parietal lobule.[1]It represents theBrodmann area39.[1]
Its significance is in transferring visual information toWernicke's area,in order to make meaning out of visually perceived words.[2]It is also involved in a number of processes related to language, number processing andspatial cognition,memory retrieval,attention,andtheory of mind.
Anatomy[edit]
Connections[edit]
Left and right angulargyriare connected by thedorsal spleniumand isthmus of thecorpus callosum.[3]
| Connected To The | Via the |
|---|---|
| ipsilateral frontal and caudallateral prefrontal and inferior frontal regions | superior longitudinal fasciculus.[4] |
| caudate | inferior occipitofrontal fasciculus[5] |
| parahippocampal gyrus[6]andhippocampus[5] | inferior longitudinal fasciculus |
| precuneusandsuperior frontal gyrus | occipitofrontal fasciculus,[7] |
| supramarginal gyrus | local arcuate[8] |
Boundaries[edit]
- Anteriorly by thesupramarginal gyrus.
- Superiorly by theintraparietal sulcus.
- Posteriorly by theparieto-occipital sulcus.
- Inferiorly the angular gyrus of the parietal lobe is continuous as thesuperiorandmiddle temporal gyri.Also, the angular sulcus, which is capped by the angular gyrus, is continuous as thesuperior temporal sulcusinferiorly.[9]
Function[edit]
The angular gyrus is the part of the brain associated with complex language functions (i.e. reading, writing and interpretation of what is written). Lesion to this part of the brain shows symptoms of theGerstmann syndrome:effects include finger agnosia, alexia (inability to read), acalculia (inability to use arithmetic operations), agraphia (inability to copy), and left-right confusion.
Language[edit]
Norman Geschwindproposed that written word is translated to internal monologue via the angular gyrus.[citation needed]
V. S. Ramachandran,and Edward Hubbard published a paper in 2003 in which they hypothesized the angular gyrus to play a role in understandingmetaphors.They stated:
There may be neurological disorders that disturb metaphor and synaesthesia. This has not been studied in detail but we have seen disturbances in the Bouba/Kiki effect (Ramachandran & Hubbard, 2001a) as well as with proverbs in patients with angular gyrus lesions. It would be interesting to see whether they have deficits in other types of synaesthetic metaphor, e.g. 'sharp cheese' or 'loud shirt'. There are also hints that patients with right hemisphere lesions show problems with metaphor. It is possible that their deficits are mainly with spatial metaphors, such as 'He stepped down as director'.[10]
The fact that the angular gyrus is proportionately much larger in hominids than other primates, and its strategic location at the crossroads of areas specialized for processing touch, hearing and vision, leads Ramachandran to believe that it is critical both to conceptual metaphors and to cross-modal abstractions more generally. However, recent research challenges this theory.
Research by Krish Sathian (Emory University) usingfunctional magnetic resonance imaging(fMRI) suggests that the angular gyrus does not play a role in creating conceptual metaphors. Sathian theorizes that conceptual metaphors activate the texture-selective somatosensory cortex in the parietal operculum.[11]
Brownsett and Wise highlight the role of the left angular gyrus in both speaking and writing.[12]
Arithmetic and spatial cognition[edit]
Since 1919,brain injuriesto the angular gyrus have been known to often causearithmeticdeficits.[13][14]Functional imaginghas shown that while other parts of theparietal lobebilaterally are involved in approximate calculations due to its link with spatiovisual abilities, the left angular gyrus together with leftInferior frontal gyrusare involved in exact calculation due to verbal arithmetic fact retrieval.[15]When activation in the left angular gyrus is greater, a person's arithmetic skills are also more competent.[16]
Attention[edit]
The right angular gyrus has been associated with spatiovisual attention toward salient features.[17][18]It may allocate attention by employing a bottom-up strategy which draws on the area's ability to attend to retrieved memories.[17]For example, the angular gyrus plays a critical role in distinguishing left from right by integrating the conceptual understanding of the language term "left" or "right" with its location in space.[19]Furthermore, the angular gyrus has been associated with orienting in three dimensional space, not because it interprets space, but because it may control attention shifts in space.[20]
Other functions[edit]
Default mode network[edit]
The angular gyrus is part of thedefault mode network,a network of brain regions activated during multi-modal activities that are independent of external stimuli.[21][22]
Awareness[edit]
The angular gyrus reacts differently to intended and consequential movement.[23]This suggests that the angular gyrus monitors the self's intended movements and uses the added information to compute differently, as it does for consequential movements. By recording the discrepancy, the angular gyrus maintains an awareness of the self.
Memory retrieval[edit]
Activation of the angular gyrus shows that not only does it mediate memory retrieval, but it also notes contradictions between what is expected from the retrieval, and what is unusual.[3]The angular gyrus can access both content and episodic memories and is useful in inferring from these the intentions of human characters.[17]Furthermore, the angular gyrus may use a feedback strategy to ascertain whether a retrieval is expected or unusual.
Out-of-body experiences[edit]
Experiments have demonstrated the ability of stimulation of the right angular gyrus to induceout-of-body experiences.[24]Stimulation of the left angular gyrus in one experiment caused a woman to perceive a shadowy person lurking behind her. The shadowy figure is actually a perceived double of the self.[25]Another such experiment gave the test subject the sensation of being on the ceiling. This is attributed to a discrepancy in the actual position of the body, and the mind's perceived location of the body.
Clinical significance[edit]
Damage to the angular gyrus manifests asGerstmann syndrome.Damage may impair one or more of the below functions.
- Dysgraphia/agraphia: deficiency in the ability to write[26][27]
- Dyscalculia/acalculia: difficulty in learning or comprehending mathematics[26][27]
- Finger agnosia:inability to distinguish the fingers on the hand[26][27]
- Left-right disorientation[26][27]
Additional images[edit]
-
Position of angular gyrus (shown in red). -
Lateral surface of left cerebral hemisphere, viewed from above. Angular gyrus is shown in orange. -
Lateral surface of left cerebral hemisphere, viewed from the side. Angular gyrus is shown in orange. -
Lateral view of a human brain, main gyri labeled. -
Cerebrum. Lateral view.Deep dissection. -
Cerebrum. Lateral view.Deep dissection. -
Angular gyrus highlighted in green on coronal T1 MRI image -
Angular gyrus highlighted in green on sagittal T1 MRI image -
Angular gyrus highlighted in green on transversal T1 MRI image
See also[edit]
References[edit]
- ^abSeghier, Mohamed L. (February 2013)."The Angular Gyrus".The Neuroscientist.19(1): 43–61.doi:10.1177/1073858412440596.ISSN1073-8584.PMC4107834.PMID22547530.
- ^John, Hall (2010).Guyton and Hall Textbook of Medical Physiology.Saunders. p. 699.ISBN978-1416045748.
- ^abPark, HJ; Kim, JJ; Lee, SK; Seok, JH; Chun, J; Kim, DI; et al. (2008)."Corpus callosal connection mapping using cortical gray matter parcellation and DT-MRI".Human Brain Mapping.29(5): 503–16.doi:10.1002/hbm.20314.PMC6870924.PMID17133394.
- ^Makris, Nikos; Kennedy, David N.; McInerney, Sean; Sorensen, A. Gregory; Wang, Ruopeng; Verne, S. Caviness Jr; Pandya, Deepak N. (2005)."Segmentation of Subcomponents within the Superior Longitudinal Fascicle in Humans: A Quantitative, In Vivo, DT-MRI Study".Cereb. Cortex.15(6): 854–869.doi:10.1093/cercor/bhh186.PMID15590909.
- ^abUddin, Lucina Q.; Supekar, Kaustubh; Amin, Hitha; Rykhlevskaia, Elena; Nguyen, Daniel A.; Greicius, Michael D.; Menon, Vinod (2010)."Dissociable Connectivity within Human Angular Gyrus and Intraparietal Sulcus: Evidence from Functional and Structural Connectivity".Cereb. Cortex.20(11): 2636–2646.doi:10.1093/cercor/bhq011.PMC2951845.PMID20154013.
- ^Rushworth, MF; Behrens, TE; Johansen-Berg, H (2006). "Connection patterns distinguish 3 regions of human parietal cortex".Cereb Cortex.16(10): 1418–1430.CiteSeerX10.1.1.504.2825.doi:10.1093/cercor/bhj079.PMID16306320.
- ^Makris, Nikos; Papadimitriou, George M.; Sorg, Scott; Kennedy, David N.; Caviness, Verne S.; Pandya, Deepak N. (2007)."The occipitofrontal fascicle in humans: A quantitative, in vivo, DT-MRI study".NeuroImage.37(4): 1100–1111.doi:10.1016/j.neuroimage.2007.05.042.PMC3769215.PMID17681797.
- ^Lee, H; Devlin, JT; Shakeshaft, C; Stewart, LH; Brennan, A; Glensman, J; Pitcher, K; Crinion, J; Mechelli, A; Frackowiak, RS; Green, DW; Price, CJ (2007)."Anatomical traces of vocabulary acquisition in the adolescent brain"(PDF).J Neurosci.27(5): 1184–1189.doi:10.1523/jneurosci.4442-06.2007.PMC6673201.PMID17267574.
- ^Gai, Dayu."Angular gyrus | Radiology Reference Article | Radiopaedia.org".Radiopaedia.doi:10.53347/rid-38811.Retrieved2022-06-15.
- ^Ramachandran, V.S.; Hubbard, E.M (2003)."The Phenomenology of Synaesthesia"(PDF).Journal of Consciousness Studies.10(8): 49–57.
- ^Simon, K; Stilla, R; Sathian, K (2011)."Metaphorically feeling:Comprehending textual metaphors actives somatosensory cortex".Brain and Language.120(3): 416–421.doi:10.1016/j.bandl.2011.12.016.PMC3318916.PMID22305051.
- ^Brownsett, Sonia L. E.; Wise, Richard J. S. (2009-06-16)."The Contribution of the Parietal Lobes to Speaking and Writing".Cerebral Cortex.20(3): 517–523.doi:10.1093/cercor/bhp120.ISSN1460-2199.PMC2820696.PMID19531538.
- ^Henschen, SL (1919)."On language, music and calculation mechanisms and their localisation in the cerebrum".Zeitschrift für die Gesamte Neurologie und Psychiatrie.52:273–298.doi:10.1007/bf02872428.S2CID123138541.
- ^Gerstmann, J (1940). "Syndrome of finger agnosia, disorientation for right and left, agraphia and acalculia—Local diagnostic value".Arch Neurol Psychiatry.44(2): 398–408.doi:10.1001/archneurpsyc.1940.02280080158009.
- ^Dehaene, S; Spelke, E; Pinel, P; Stanescu, R; Tsivkin, S (1999). "Sources of mathematical thinking: behavioral and brain-imaging evidence".Science.284(5416): 970–4.Bibcode:1999Sci...284..970D.doi:10.1126/science.284.5416.970.PMID10320379.
- ^Grabner, RH; Ansari, D; Reishofer, G; Stern, E; Ebner, F; Neuper, C (2007). "Individual differences in mathematical competence predict parietal brain activation during mental calculation".NeuroImage.38(2): 346–56.doi:10.1016/j.neuroimage.2007.07.041.PMID17851092.S2CID18960661.
- ^abcSeghier, M. L. (2012)."The angular gyrus: multiple function ad multiple subdivisions".Neuroscientist.19(1): 43–61.doi:10.1177/1073858412440596.PMC4107834.PMID22547530.
- ^Arsalidou, M; Taylor, MJ (2011). "Is 2+2=4? Meta-analyses of brain areas needed for numbers and calculations".NeuroImage.54(3): 2382–93.doi:10.1016/j.neuroimage.2010.10.009.PMID20946958.S2CID140205603.
- ^Hirnstein, M; Bayer, U; Ellison, A; Hausmann, M (2011). "TMS over the left angular gyrus impairs the ability to discriminate left from right".Neuropsychologia.49(1): 29–33.doi:10.1016/j.neuropsychologia.2010.10.028.PMID21035475.S2CID8460451.
- ^Chen, Q; Weidner, R; Vossel, S; Weiss, PH; Fink, GR (Sep 2012)."Neural mechanisms of attentional reorienting in three-dimensional space".J Neurosci.32(39): 13352–62.doi:10.1523/jneurosci.1772-12.2012.PMC6621370.PMID23015426.
- ^Murphy, Charlotte; Jefferies, Elizabeth; Rueschemeyer, Shirley-Ann; Sormaz, Mladen; Wang, Hao-ting; Margulies, Daniel S.; Smallwood, Jonathan (2018-05-01)."Distant from input: Evidence of regions within the default mode network supporting perceptually-decoupled and conceptually-guided cognition".NeuroImage.171:393–401.doi:10.1016/j.neuroimage.2018.01.017.ISSN1053-8119.PMC5883322.PMID29339310.
- ^Vatansever, D.; Manktelow, A. E.; Sahakian, B. J.; Menon, D. K.; Stamatakis, E. A. (January 2017)."Angular default mode network connectivity across working memory load".Human Brain Mapping.38(1): 41–52.doi:10.1002/hbm.23341.ISSN1097-0193.PMC6866899.PMID27489137.
- ^Farrer C, Frey SH, Van Horn JD, Tunik E, Turk D, Inati S, Grafton ST. The angular gyrus computes action awareness representations. Centre de Neuroscience Cognitive.
- ^Out-of-Body Experience? Your Brain Is to Blame - New York Times
- ^Arzy, S.; Seeck, M.; Ortigue, S.; Spinelli, L.; Blanke, O. (2006)."Induction of an illusory shadow person: Stimulation of a site on the brain's left hemisphere prompts the creepy feeling that somebody is close by".Nature.443(21): 287.doi:10.1038/443287a.PMID16988702.S2CID4338465.
- ^abcdVallar G (July 2007). "Spatial neglect, Balint-Homes' and Gerstmann's syndrome, and other spatial disorders".CNS Spectr.12(7): 527–36.doi:10.1017/S1092852900021271.PMID17603404.S2CID45201083.
- ^abcdCarota A, Di Pietro M, Ptak R, Poglia D, Schnider A (2004). "Defective spatial imagery with pure Gerstmann's syndrome".Eur. Neurol.52(1): 1–6.doi:10.1159/000079251.PMID15218337.S2CID22897847.
External links[edit]
