title: Effortful retrieval reduces hippocampal activity and impairs incidental encoding.
abstract: Functional imaging studies frequently report that the hippocampus is engaged by successful episodic memory retrieval. However, considering that concurrent encoding of the background environment occurs during retrieval and influences medial temporal lobe activity, it is plausible that hippocampal encoding functions are reduced with increased attentional engagement during effortful retrieval. Expanding upon evidence that retrieval efforts suppress activity in hippocampal regions implicated in encoding, this study examines the influence of retrieval effort on encoding performance and the interactive effects of encoding and retrieval on hippocampal and neocortical activity. Functional magnetic resonance imaging was conducted while subjects performed a word recognition task with incidental picture encoding. Both lower memory strength and increased search duration were associated with encoding failure and reduced hippocampal and default network activity. Activity in the anterior hippocampus tracked encoding, which was more strongly deactivated when incidental encoding was unsuccessful. These findings highlight potential contributions from background encoding processes to hippocampal activations during neuroimaging studies of episodic memory retrieval.
authors: Department of Neurosciences, University of California, San Diego, California, USA.
authors: Emilie T
authors: ET
authors: Reas
authors: James B
authors: JB
authors: Brewer
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001245:Association Learning / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006624:Hippocampus / Q000098:blood supply / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000209:etiology*; D011939:Mental Recall / Q000502:physiology*; D009415:Nerve Net / Q000098:blood supply / Q000502:physiology; D010100:Oxygen / Q000097:blood; D011930:Reaction Time; D021641:Recognition, Psychology / Q000502:physiology; D014825:Vocabulary; D055815:Young Adult
chemical_list: D010100:Oxygen
references: Hippocampus. 1999;9(1):7-24
references: 10088896
references: PLoS One. 2011 Apr 11;6(4):e17463
references: 21494597
references: J Neurosci. 2005 Feb 2;25(5):1203-10
references: 15689557
references: J Cogn Neurosci. 2010 Jan;22(1):109-23
references: 19199424
references: Neuron. 2000 Sep;27(3):623-33
references: 11055443
references: Hippocampus. 2011 Jan;21(1):9-21
references: 20014387
references: Hippocampus. 1994 Aug;4(4):483-95
references: 7874239
references: Proc Natl Acad Sci U S A. 1996 Jan 9;93(1):321-5
references: 8552630
references: Science. 2005 Jul 22;309(5734):619-23
references: 16040709
references: Science. 1991 Sep 20;253(5026):1380-6
references: 1896849
references: PLoS Biol. 2009 Jan 13;7(1):e11
references: 19143473
references: Learn Mem. 2005 Jul-Aug;12(4):375-82
references: 16027176
references: J Neurosci. 2005 Mar 30;25(13):3280-6
references: 15800182
references: Neuron. 2010 Jan 14;65(1):7-19
references: 20152109
references: Cereb Cortex. 2013 Jan;23(1):80-96
references: 22275474
references: J Neurosci. 2010 Mar 31;30(13):4707-16
references: 20357121
references: Hippocampus. 1998;8(4):313-22
references: 9744418
references: Science. 2003 Jun 6;300(5625):1578-81
references: 12791995
references: Hum Brain Mapp. 1997;5(5):329-40
references: 20408237
references: Learn Mem. 2011 Jul 20;18(8):523-8
references: 21775513
references: J Neurosci. 2000 Oct 15;20(20):7776-81
references: 11027241
references: Science. 2012 Jul 27;337(6093):485-7
references: 22837528
references: Proc Natl Acad Sci U S A. 2005 Jul 5;102(27):9685-90
references: 15980148
references: Ann N Y Acad Sci. 2000 Jun;911:175-91
references: 10911874
references: Front Hum Neurosci. 2011 Oct 30;5:112
references: 22046159
references: J Neurophysiol. 2006 Oct;96(4):1902-11
references: 16738210
references: Proc Natl Acad Sci U S A. 2001 Jan 16;98(2):676-82
references: 11209064
references: Cereb Cortex. 2011 Jan;21(1):22-34
references: 20363808
references: Trends Cogn Sci. 2011 May;15(5):210-7
references: 21481629
references: Am J Clin Oncol. 2009 Feb;32(1):20-2
references: 19194118
references: Comput Biomed Res. 1996 Jun;29(3):162-73
references: 8812068
references: Neurosci Biobehav Rev. 2012 Aug;36(7):1579-96
references: 21964564
references: Neuroimage. 2004;23 Suppl 1:S208-19
references: 15501092
references: J Cogn Neurosci. 2010 Mar;22(3):513-25
references: 19301994
references: Hum Brain Mapp. 1999;8(2-3):109-14
references: 10524601
references: Rev Neurosci. 2004;15(5):333-51
references: 15575490
references: Science. 1998 Aug 21;281(5380):1185-7
references: 9712581
references: J Cogn Neurosci. 2003 Apr 1;15(3):394-408
references: 12729491
references: J Neurol Neurosurg Psychiatry. 1957 Feb;20(1):11-21
references: 13406589
references: Hippocampus. 2012 Jun;22(6):1429-37
references: 22076964
references: Science. 1966 Aug 5;153(3736):652-4
references: 5939936
references: AJNR Am J Neuroradiol. 1998 Apr;19(4):659-71
references: 9576651
references: Science. 1997 Apr 11;276(5310):264-6
references: 9092477
references: Nat Neurosci. 2010 Apr;13(4):501-6
references: 20190745
references: J Neurosci. 2010 Jun 23;30(25):8541-50
references: 20573901
references: J Neurosci. 2003 Jul 30;23(17):6748-53
references: 12890767
references: Cereb Cortex. 2002 Oct;12(10):1048-56
references: 12217968
references: Ann N Y Acad Sci. 2008 Mar;1124:1-38
references: 18400922
references: Learn Mem. 2010 Dec 16;18(1):15-8
references: 21164173
references: Psychon Bull Rev. 2006 Dec;13(6):1023-7
references: 17484429
references: Proc Natl Acad Sci U S A. 2009 Aug 25;106(34):14617-21
references: 19706549
references: Proc Natl Acad Sci U S A. 2008 Sep 16;105(37):14228-33
references: 18757724
references: Nat Neurosci. 2000 Nov;3(11):1149-52
references: 11036273
references: Annu Rev Neurosci. 2007;30:123-52
references: 17417939
references: Annu Rev Neurosci. 2004;27:279-306
references: 15217334
references: Neuron. 2012 Jul 12;75(1):168-79
references: 22794270
references: Science. 1999 Sep 3;285(5433):1582-5
references: 10477525
references: Science. 2007 Feb 16;315(5814):961-6
references: 17303747
references: Hum Brain Mapp. 2007 Oct;28(10):959-66
references: 17133381
references: J Cogn Neurosci. 2001 Apr 1;13(3):406-15
references: 11371316
references: Science. 1998 Aug 21;281(5380):1188-91
references: 9712582
references: J Cogn Neurosci. 2008 Mar;20(3):432-46
references: 18004952
references: Science. 2008 Mar 21;319(5870):1640-2
references: 18356518