@article{ Mehta_etal00b,
  author = {Mehta, A. D. and Ulbert, I. and Schroeder, C. E.},
  title = {Intermodal Selective Attention in Monkeys. {II:} Physiological Mechanisms
	of Modulation},
  journal = {Cerebral Cortex},
  year = {2000},
  volume = {10},
  pages = {359-70},
  number = {4},
  abstract = { Of all areas studied in the accompanying study, attention effects
	were most consistent and well resolved in V4. In this study, to define
	some of the anatomical circuits and neural processes underlying the
	influence of attention, we examined the laminar distribution and
	physiology of attention effects in V4 and in two lower areas, V1
	and V2. Laminar event-related potential (ERP), current source density
	(CSD) and multiunit activity (MUA) profiles allowed identification
	of processes occurring in the local ensembles, as well as their sequence
	and laminar distribution. These methods also permitted us to analyze
	the brain processes reflected in attention-sensitive components of
	the surface ERP. As outlined in the previous study, the first robust
	modulation by attention occurred in V4 during the 100-300 ms poststimulus
	interval. This is the time frame of the net refractoriness which
	follows the net local excitatory response to luminance increment.
	Over this interval, attention reduced CSD amplitudes and increased
	action potential firing rates, findings consistent with disinhibition
	as a mechanism for attention in V4. Similar effects were observed
	during the 100-300 ms time frame in V2. In V4, attention had no effect
	on the initial excitatory response at the depth of lamina 4, but
	it did produce large modulations in supragranular and deep laminae,
	origins of both feedforward and feedback projections. Attentional
	modulation in V2 was later than in V4 and concentrated in extragranular
	laminae, with no modulation of the initial layer 4 response. Attentional
	modulation in V1 was smaller and still later than that in V2 and
	was focused in the supragranular laminae. In this paradigm, attention
	did not modulate either the response in lateral geniculate nucleus
	(LGN) or the initial excitation in lamina 4C of V1. The timing of
	effects across areas and the laminar distribution of effects within
	areas indicate that attention effects are mediated by feedback projections.
	Moreover, our findings suggest that attention may increase the perceptual
	salience of stimuli by reducing stimulus-evoked refractoriness and/or
	inhibition in cortical ensembles. Finally, attentional modulation
	of transmembrane current flow in V4 produced a sustained negative
	deflection in the laminar ERP profile, that was manifested in the
	ERP over the occipital surface. This posits a mechanism for the 'selection
	negativity’, a scalp ERP effect noted under similar experimental
	conditions in human subjects.}
}

{"_id":"akRsJaGyBSPg8k8q5","bibbaseid":"mehta-ulbert-schroeder-intermodalselectiveattentioninmonkeysiiphysiologicalmechanismsofmodulation-2000","downloads":0,"creationDate":"2015-02-08T05:14:51.287Z","title":"Intermodal Selective Attention in Monkeys. II: Physiological Mechanisms of Modulation","author_short":["Mehta, A.<nbsp>D.","Ulbert, I.","Schroeder, C.<nbsp>E."],"year":2000,"bibtype":"article","biburl":"http://cnslab.mb.jhu.edu/niebase.bib","bibdata":{"abstract":"Of all areas studied in the accompanying study, attention effects were most consistent and well resolved in V4. In this study, to define some of the anatomical circuits and neural processes underlying the influence of attention, we examined the laminar distribution and physiology of attention effects in V4 and in two lower areas, V1 and V2. Laminar event-related potential (ERP), current source density (CSD) and multiunit activity (MUA) profiles allowed identification of processes occurring in the local ensembles, as well as their sequence and laminar distribution. These methods also permitted us to analyze the brain processes reflected in attention-sensitive components of the surface ERP. As outlined in the previous study, the first robust modulation by attention occurred in V4 during the 100-300 ms poststimulus interval. This is the time frame of the net refractoriness which follows the net local excitatory response to luminance increment. Over this interval, attention reduced CSD amplitudes and increased action potential firing rates, findings consistent with disinhibition as a mechanism for attention in V4. Similar effects were observed during the 100-300 ms time frame in V2. In V4, attention had no effect on the initial excitatory response at the depth of lamina 4, but it did produce large modulations in supragranular and deep laminae, origins of both feedforward and feedback projections. Attentional modulation in V2 was later than in V4 and concentrated in extragranular laminae, with no modulation of the initial layer 4 response. Attentional modulation in V1 was smaller and still later than that in V2 and was focused in the supragranular laminae. In this paradigm, attention did not modulate either the response in lateral geniculate nucleus (LGN) or the initial excitation in lamina 4C of V1. The timing of effects across areas and the laminar distribution of effects within areas indicate that attention effects are mediated by feedback projections. Moreover, our findings suggest that attention may increase the perceptual salience of stimuli by reducing stimulus-evoked refractoriness and/or inhibition in cortical ensembles. Finally, attentional modulation of transmembrane current flow in V4 produced a sustained negative deflection in the laminar ERP profile, that was manifested in the ERP over the occipital surface. This posits a mechanism for the 'selection negativity’, a scalp ERP effect noted under similar experimental conditions in human subjects.","author":["Mehta, A. D.","Ulbert, I.","Schroeder, C. E."],"author_short":["Mehta, A.<nbsp>D.","Ulbert, I.","Schroeder, C.<nbsp>E."],"bibtex":"@article{ Mehta_etal00b,\n author = {Mehta, A. D. and Ulbert, I. and Schroeder, C. E.},\n title = {Intermodal Selective Attention in Monkeys. {II:} Physiological Mechanisms\n\tof Modulation},\n journal = {Cerebral Cortex},\n year = {2000},\n volume = {10},\n pages = {359-70},\n number = {4},\n abstract = { Of all areas studied in the accompanying study, attention effects\n\twere most consistent and well resolved in V4. In this study, to define\n\tsome of the anatomical circuits and neural processes underlying the\n\tinfluence of attention, we examined the laminar distribution and\n\tphysiology of attention effects in V4 and in two lower areas, V1\n\tand V2. Laminar event-related potential (ERP), current source density\n\t(CSD) and multiunit activity (MUA) profiles allowed identification\n\tof processes occurring in the local ensembles, as well as their sequence\n\tand laminar distribution. These methods also permitted us to analyze\n\tthe brain processes reflected in attention-sensitive components of\n\tthe surface ERP. As outlined in the previous study, the first robust\n\tmodulation by attention occurred in V4 during the 100-300 ms poststimulus\n\tinterval. This is the time frame of the net refractoriness which\n\tfollows the net local excitatory response to luminance increment.\n\tOver this interval, attention reduced CSD amplitudes and increased\n\taction potential firing rates, findings consistent with disinhibition\n\tas a mechanism for attention in V4. Similar effects were observed\n\tduring the 100-300 ms time frame in V2. In V4, attention had no effect\n\ton the initial excitatory response at the depth of lamina 4, but\n\tit did produce large modulations in supragranular and deep laminae,\n\torigins of both feedforward and feedback projections. Attentional\n\tmodulation in V2 was later than in V4 and concentrated in extragranular\n\tlaminae, with no modulation of the initial layer 4 response. Attentional\n\tmodulation in V1 was smaller and still later than that in V2 and\n\twas focused in the supragranular laminae. In this paradigm, attention\n\tdid not modulate either the response in lateral geniculate nucleus\n\t(LGN) or the initial excitation in lamina 4C of V1. The timing of\n\teffects across areas and the laminar distribution of effects within\n\tareas indicate that attention effects are mediated by feedback projections.\n\tMoreover, our findings suggest that attention may increase the perceptual\n\tsalience of stimuli by reducing stimulus-evoked refractoriness and/or\n\tinhibition in cortical ensembles. Finally, attentional modulation\n\tof transmembrane current flow in V4 produced a sustained negative\n\tdeflection in the laminar ERP profile, that was manifested in the\n\tERP over the occipital surface. This posits a mechanism for the 'selection\n\tnegativity’, a scalp ERP effect noted under similar experimental\n\tconditions in human subjects.}\n}","bibtype":"article","id":"Mehta_etal00b","journal":"Cerebral Cortex","key":"Mehta_etal00b","number":"4","pages":"359-70","title":"Intermodal Selective Attention in Monkeys. II: Physiological Mechanisms of Modulation","type":"article","volume":"10","year":"2000","bibbaseid":"mehta-ulbert-schroeder-intermodalselectiveattentioninmonkeysiiphysiologicalmechanismsofmodulation-2000","role":"author","urls":{},"downloads":0},"search_terms":["intermodal","selective","attention","monkeys","physiological","mechanisms","modulation","mehta","ulbert","schroeder"],"keywords":[],"authorIDs":[],"dataSources":["ErLXoH8mqSjESnrN5"]}