title: Dissociation of neural mechanisms underlying orientation processing in humans.
abstract: Orientation selectivity is a fundamental, emergent property of neurons in early visual cortex, and the discovery of that property has dramatically shaped how we conceptualize visual processing. However, much remains unknown about the neural substrates of this basic building block of perception, and what is known primarily stems from animal physiology studies. To probe the neural concomitants of orientation processing in humans, we employed repetitive transcranial magnetic stimulation (rTMS), which can significantly attenuate neuronal spiking activity, hemodynamic responses, and local field potentials within a focused cortical region. Using rTMS to suppress neural responses evoked by stimuli falling within a local region of the visual field, we were able to dissociate two distinct components of the neural circuitry underlying orientation processing: selectivity and contextual effects. Orientation selectivity gauged by masking was unchanged by rTMS, whereas an otherwise robust orientation repulsion illusion was weakened after rTMS. This dissociation implies that orientation processing in humans relies on distinct mechanisms, only one of which was impacted by rTMS. These results are consistent with models positing that orientation selectivity is governed by patterns of convergence of thalamic afferents onto cortical neurons, with intracortical activity then shaping population responses amongst those cortical neurons.
authors.affiliation: Vanderbilt Vision Research Center, Vanderbilt University, Nashville, TN 37204, USA. s.ling@vanderbilt.edu
authors.forename: Sam
authors.initials: S
authors.lastname: Ling
authors.forename: Joel
authors.initials: J
authors.lastname: Pearson
authors.forename: Randolph
authors.initials: R
authors.lastname: Blake
mesh_terms: D000200:Action Potentials; D006801:Humans; D008954:Models, Biological; D009475:Neurons, Afferent / Q000502:physiology; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation; D050781:Transcranial Magnetic Stimulation; D014796:Visual Perception / Q000502:physiology
references.citation: Science. 2007 Sep 28;317(5846):1918-21
references.pmid: 17901333
references.citation: J Opt Soc Am. 1980 Dec;70(12):1458-71
references.pmid: 7463185
references.citation: Nat Rev Neurosci. 2007 Jul;8(7):522-35
references.pmid: 17585305
references.citation: J Physiol. 1962 Jan;160:106-54
references.pmid: 14449617
references.citation: Proc Biol Sci. 2000 Sep 7;267(1454):1705-10
references.pmid: 12233765
references.citation: Neuron. 2003 Jun 5;38(5):689-99
references.pmid: 12797955
references.citation: Nature. 2000 Jul 13;406(6792):147-50
references.pmid: 10910346
references.citation: Psychol Sci. 2009 Nov;20(11):1348-55
references.pmid: 19788529
references.citation: Science. 1988 Apr 15;240(4850):338-40
references.pmid: 3353728
references.citation: J Neurosci. 1989 Dec;9(12):4287-302
references.pmid: 2593002
references.citation: J Neurophysiol. 1979 Sep;42(5):1264-70
references.pmid: 490197
references.citation: Nat Neurosci. 1999 Aug;2(8):767-71
references.pmid: 10412068
references.citation: Curr Biol. 2005 Dec 6;15(23):2142-8
references.pmid: 16332541
references.citation: Nature. 1996 Mar 21;380(6571):249-52
references.pmid: 8637573
references.citation: J Vis. 2005 Jun 30;5(6):556-70
references.pmid: 16097868
references.citation: J Neurophysiol. 2002 Aug;88(2):888-913
references.pmid: 12163540
references.citation: Exp Brain Res. 1972;15(4):439-40
references.pmid: 5079475
references.citation: Vision Res. 1985;25(10):1459-67
references.pmid: 4090280
references.citation: J Physiol. 1968 Mar;195(1):215-43
references.pmid: 4966457
references.citation: Neuron. 1998 Jun;20(6):1177-89
references.pmid: 9655505
references.citation: Curr Biol. 2004 May 4;14(9):744-51
references.pmid: 15120065
references.citation: Neuron. 2009 Apr 30;62(2):291-303
references.pmid: 19409273
references.citation: Eur J Neurosci. 2004 Apr;19(7):1950-62
references.pmid: 15078569
references.citation: Vision Res. 2009 Jan;49(1):164-72
references.pmid: 18977381
references.citation: Exp Brain Res. 1982;46(3):457-61
references.pmid: 7095050
references.citation: Nat Neurosci. 2005 Feb;8(2):194-201
references.pmid: 15665876
references.citation: Vision Res. 1985;25(10):1469-76
references.pmid: 4090281
references.citation: J Neurosci. 2001 Jun 1;21(11):4002-15
references.pmid: 11356887
references.citation: J Neurosci. 1995 Aug;15(8):5448-65
references.pmid: 7643194
references.citation: Vis Neurosci. 1992 Aug;9(2):181-97
references.pmid: 1504027
references.citation: Curr Opin Neurobiol. 1997 Aug;7(4):514-22
references.pmid: 9287203
references.citation: Vision Res. 2000;40(20):2711-22
references.pmid: 10960647
references.citation: Neuron. 2008 Feb 28;57(4):482-97
references.pmid: 18304479
references.citation: Science. 1994 May 27;264(5163):1333-6
references.pmid: 8191289
references.citation: J Neurosci. 1998 Aug 1;18(15):5908-27
references.pmid: 9671678
references.citation: Vision Res. 2002 Apr;42(9):1165-84
references.pmid: 11997055
references.citation: Annu Rev Neurosci. 2000;23:441-71
references.pmid: 10845071