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Zagha E. Shaping the Cortical Landscape: Functions and Mechanisms of Top-Down Cortical Feedback Pathways. Front Syst Neurosci 2020; 14:33. [PMID: 32587506 PMCID: PMC7299084 DOI: 10.3389/fnsys.2020.00033] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 05/13/2020] [Indexed: 11/29/2022] Open
Abstract
Cortical feedback pathways are proposed to guide cognition and behavior according to context and goal-direction. At the cellular level, cortical feedback pathways target multiple excitatory and inhibitory populations. However, we currently lack frameworks that link how the cellular mechanisms of cortical feedback pathways underlie their cognitive/behavioral functions. To establish this link, we expand on the framework of signal routing, the ability of cortical feedback pathways to proactively modulate how feedforward signals are propagated throughout the cortex. We propose that cortical feedback modulates routing through multiple mechanisms: preparing intended motor representations, setting the trigger conditions for evoking cortical outputs, altering coupling strengths between cortical regions, and suppressing expected sensory representations. In developing this framework, we first define the anatomy of cortical feedback pathways and identify recent advances in studying their functions at high specificity and resolution. Second, we review the diverse functions of cortical feedback pathways throughout the cortical hierarchy and evaluate these functions from the framework of signal routing. Third, we review the conserved cellular targets and circuit impacts of cortical feedback. Fourth, we introduce the concept of the “cortical landscape,” a graphical depiction of the routes through cortex that are favored at a specific moment in time. We propose that the cortical landscape, analogous to energy landscapes in physics and chemistry, can capture important features of signal routing including coupling strength, trigger conditions, and preparatory states. By resolving the cortical landscape, we may be able to quantify how the cellular processes of cortical feedback ultimately shape cognition and behavior.
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Affiliation(s)
- Edward Zagha
- Neuroscience Graduate Program, Department of Psychology, University of California, Riverside, Riverside, CA, United States
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2
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Raz A, Grady SM, Krause BM, Uhlrich DJ, Manning KA, Banks MI. Preferential effect of isoflurane on top-down vs. bottom-up pathways in sensory cortex. Front Syst Neurosci 2014; 8:191. [PMID: 25339873 PMCID: PMC4188029 DOI: 10.3389/fnsys.2014.00191] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 09/18/2014] [Indexed: 12/31/2022] Open
Abstract
The mechanism of loss of consciousness (LOC) under anesthesia is unknown. Because consciousness depends on activity in the cortico-thalamic network, anesthetic actions on this network are likely critical for LOC. Competing theories stress the importance of anesthetic actions on bottom-up “core” thalamo-cortical (TC) vs. top-down cortico-cortical (CC) and matrix TC connections. We tested these models using laminar recordings in rat auditory cortex in vivo and murine brain slices. We selectively activated bottom-up vs. top-down afferent pathways using sensory stimuli in vivo and electrical stimulation in brain slices, and compared effects of isoflurane on responses evoked via the two pathways. Auditory stimuli in vivo and core TC afferent stimulation in brain slices evoked short latency current sinks in middle layers, consistent with activation of core TC afferents. By contrast, visual stimuli in vivo and stimulation of CC and matrix TC afferents in brain slices evoked responses mainly in superficial and deep layers, consistent with projection patterns of top-down afferents that carry visual information to auditory cortex. Responses to auditory stimuli in vivo and core TC afferents in brain slices were significantly less affected by isoflurane compared to responses triggered by visual stimuli in vivo and CC/matrix TC afferents in slices. At a just-hypnotic dose in vivo, auditory responses were enhanced by isoflurane, whereas visual responses were dramatically reduced. At a comparable concentration in slices, isoflurane suppressed both core TC and CC/matrix TC responses, but the effect on the latter responses was far greater than on core TC responses, indicating that at least part of the differential effects observed in vivo were due to local actions of isoflurane in auditory cortex. These data support a model in which disruption of top-down connectivity contributes to anesthesia-induced LOC, and have implications for understanding the neural basis of consciousness.
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Affiliation(s)
- Aeyal Raz
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin Madison, WI, USA ; Department of Anesthesiology, Rabin Medical Center, Petah-Tikva, Israel, Affiliated with Sackler School of Medicine, Tel Aviv University Tel Aviv, Israel
| | - Sean M Grady
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin Madison, WI, USA
| | - Bryan M Krause
- Neuroscience Training Program, University of Wisconsin Madison, WI, USA
| | - Daniel J Uhlrich
- Department of Neuroscience, University of Wisconsin Madison, WI, USA
| | - Karen A Manning
- Department of Neuroscience, University of Wisconsin Madison, WI, USA
| | - Matthew I Banks
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin Madison, WI, USA ; Department of Neuroscience, University of Wisconsin Madison, WI, USA
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Shimegi S, Ishikawa A, Kida H, Sakamoto H, Hara SI, Sato H. Spatiotemporal characteristics of surround suppression in primary visual cortex and lateral geniculate nucleus of the cat. J Neurophysiol 2014; 112:603-19. [DOI: 10.1152/jn.00221.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the primary visual cortex (V1), a neuronal response to stimulation of the classical receptive field (CRF) is predominantly suppressed by a stimulus presented outside the CRF (extraclassical receptive field, ECRF), a phenomenon referred to as ECRF suppression. To elucidate the neuronal mechanisms and origin of ECRF suppression in V1 of anesthetized cats, we examined the temporal properties of the spatial extent and orientation specificity of ECRF suppression in V1 and the lateral geniculate nucleus (LGN), using stationary-flashed sinusoidal grating. In V1, we found three components of ECRF suppression: 1) local and fast, 2) global and fast, and 3) global and late. The local and fast component, which resulted from within 2° of the boundary of the CRF, started no more than 10 ms after the onset of the CRF response and exhibited low specificity for the orientation of the ECRF stimulus. These spatiotemporal properties corresponded to those of geniculate ECRF suppression, suggesting that the local and fast component of V1 is inherited from the LGN. In contrast, the two global components showed rather large spatial extents ∼5° from the CRF boundary and high specificity for orientation, suggesting that their possible origin is the cortex, not the LGN. Correspondingly, the local component was observed in all neurons of the thalamocortical recipient layer, while the global component was biased toward other layers. Therefore, we conclude that both subcortical and cortical mechanisms with different spatiotemporal properties are involved in ECRF suppression.
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Affiliation(s)
- Satoshi Shimegi
- Graduate School of Medicine, Osaka University, Toyonaka, Osaka, Japan
- Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka, Japan; and
| | - Ayako Ishikawa
- Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka, Japan; and
| | - Hiroyuki Kida
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Hiroshi Sakamoto
- Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka, Japan; and
| | - Sin-ichiro Hara
- Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka, Japan; and
| | - Hiromichi Sato
- Graduate School of Medicine, Osaka University, Toyonaka, Osaka, Japan
- Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka, Japan; and
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4
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Cattan S, Bachatene L, Bharmauria V, Jeyabalaratnam J, Milleret C, Molotchnikoff S. Comparative analysis of orientation maps in areas 17 and 18 of the cat primary visual cortex following adaptation. Eur J Neurosci 2014; 40:2554-63. [DOI: 10.1111/ejn.12616] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/07/2014] [Accepted: 04/10/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Sarah Cattan
- Département de sciences biologiques; Université de Montréal; Pavillon Marie-Victorin, C.P. 6128, succ. Centre-ville Montréal QC H3C 3J7 Canada
| | - Lyes Bachatene
- Département de sciences biologiques; Université de Montréal; Pavillon Marie-Victorin, C.P. 6128, succ. Centre-ville Montréal QC H3C 3J7 Canada
| | - Vishal Bharmauria
- Département de sciences biologiques; Université de Montréal; Pavillon Marie-Victorin, C.P. 6128, succ. Centre-ville Montréal QC H3C 3J7 Canada
| | - Jeyadarshan Jeyabalaratnam
- Département de sciences biologiques; Université de Montréal; Pavillon Marie-Victorin, C.P. 6128, succ. Centre-ville Montréal QC H3C 3J7 Canada
| | - Chantal Milleret
- Neural Bases of Spatial Memory and Navigation; CIRB - Collège de France (CNRS UMR 7241, INSERM U1050, UPMC ED 158, MEMOLIFE PSL); Paris France
| | - Stéphane Molotchnikoff
- Département de sciences biologiques; Université de Montréal; Pavillon Marie-Victorin, C.P. 6128, succ. Centre-ville Montréal QC H3C 3J7 Canada
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Jeffs J, Federer F, Ichida JM, Angelucci A. High-resolution mapping of anatomical connections in marmoset extrastriate cortex reveals a complete representation of the visual field bordering dorsal V2. Cereb Cortex 2013; 23:1126-47. [PMID: 22523183 PMCID: PMC3615347 DOI: 10.1093/cercor/bhs088] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The primate visual cortex consists of many areas. The posterior areas (V1, V2, V3, and middle temporal) are thought to be common to all primate species. However, the organization of cortex immediately anterior to area V2 (the "third tier" cortex) remains controversial, particularly in New World primates. The main point of contention has been whether the third tier cortex consists of a single area V3, representing lower and upper visual quadrants in dorsal and ventral cortex, respectively, or of 2 distinct areas (the dorsomedial [DM] area and a V3-like area). Resolving this controversy is crucial to understand the function and evolution of the third tier cortex. We have addressed this issue in marmosets, by performing high-precision mapping of corticocortical connections in cortex bordering dorsal V2. Multiple closely spaced neuroanatomical tracer injections were placed across the full width of dorsal V2 or adjacent anterior cortex, and the location of resulting labeled cells mapped throughout whole flattened visual cortex. The resulting topographic patterns of labeled connections allowed us to define areas and their boundaries. We found that a complete representation of the visual field borders dorsal V2 and that the third tier cortex consists of 2 distinct areas. These results unequivocally support the DM model.
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Affiliation(s)
- Janelle Jeffs
- Department of Ophthalmology, Moran Eye Center
- Department of Bioengineering
| | - Frederick Federer
- Department of Ophthalmology, Moran Eye Center
- Neuroscience Program, University of Utah, Salt Lake City, UT 84132, USA
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Zheng L, Yao H. Stimulus-entrained oscillatory activity propagates as waves from area 18 to 17 in cat visual cortex. PLoS One 2012; 7:e41960. [PMID: 22848673 PMCID: PMC3405032 DOI: 10.1371/journal.pone.0041960] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Accepted: 06/27/2012] [Indexed: 11/21/2022] Open
Abstract
Previous studies in cat visual cortex reported that area 18 can actively drive neurons in area 17 through cortico-cortical projections. However, the dynamics of such cortico-cortical interaction remains unclear. Here we used multielectrode arrays to examine the spatiotemporal pattern of neuronal activity in cat visual cortex across the 17/18 border. We found that full-field contrast reversal gratings evoked oscillatory wave activity propagating from area 18 to 17. The wave direction was independent of the grating orientation, and could not be accounted for by the spatial distribution of receptive field latencies, suggesting that the waves are largely mediated by intrinsic connections in the cortex. Different from the evoked waves, spontaneous waves propagated along both directions across the 17/18 border. Together, our results suggest that visual stimulation may enhance the flow of information from area 18 to 17.
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Affiliation(s)
- Lian Zheng
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- Graduate School of Chinese Academy of Sciences, Shanghai, China
| | - Haishan Yao
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- * E-mail:
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7
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Chavane F, Sharon D, Jancke D, Marre O, Frégnac Y, Grinvald A. Lateral Spread of Orientation Selectivity in V1 is Controlled by Intracortical Cooperativity. Front Syst Neurosci 2011; 5:4. [PMID: 21629708 PMCID: PMC3100672 DOI: 10.3389/fnsys.2011.00004] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 01/14/2011] [Indexed: 11/13/2022] Open
Abstract
Neurons in the primary visual cortex receive subliminal information originating from the periphery of their receptive fields (RF) through a variety of cortical connections. In the cat primary visual cortex, long-range horizontal axons have been reported to preferentially bind to distant columns of similar orientation preferences, whereas feedback connections from higher visual areas provide a more diverse functional input. To understand the role of these lateral interactions, it is crucial to characterize their effective functional connectivity and tuning properties. However, the overall functional impact of cortical lateral connections, whatever their anatomical origin, is unknown since it has never been directly characterized. Using direct measurements of postsynaptic integration in cat areas 17 and 18, we performed multi-scale assessments of the functional impact of visually driven lateral networks. Voltage-sensitive dye imaging showed that local oriented stimuli evoke an orientation-selective activity that remains confined to the cortical feedforward imprint of the stimulus. Beyond a distance of one hypercolumn, the lateral spread of cortical activity gradually lost its orientation preference approximated as an exponential with a space constant of about 1 mm. Intracellular recordings showed that this loss of orientation selectivity arises from the diversity of converging synaptic input patterns originating from outside the classical RF. In contrast, when the stimulus size was increased, we observed orientation-selective spread of activation beyond the feedforward imprint. We conclude that stimulus-induced cooperativity enhances the long-range orientation-selective spread.
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Affiliation(s)
- Frédéric Chavane
- Department of Neurobiology, Weizmann Institute of Science Rehovot, Israel
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8
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Abstract
In this letter, we develop and simulate a large-scale network of spiking neurons that approximates the inference computations performed by graphical models. Unlike previous related schemes, which used sum and product operations in either the log or linear domains, the current model uses an inference scheme based on the sum and maximization operations in the log domain. Simulations show that using these operations, a large-scale circuit, which combines populations of spiking neurons as basic building blocks, is capable of finding close approximations to the full mathematical computations performed by graphical models within a few hundred milliseconds. The circuit is general in the sense that it can be wired for any graph structure, it supports multistate variables, and it uses standard leaky integrate-and-fire neuronal units. Following previous work, which proposed relations between graphical models and the large-scale cortical anatomy, we focus on the cortical microcircuitry and propose how anatomical and physiological aspects of the local circuitry may map onto elements of the graphical model implementation. We discuss in particular the roles of three major types of inhibitory neurons (small fast-spiking basket cells, large layer 2/3 basket cells, and double-bouquet neurons), subpopulations of strongly interconnected neurons with their unique connectivity patterns in different cortical layers, and the possible role of minicolumns in the realization of the population-based maximum operation.
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Affiliation(s)
- Shai Litvak
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel.
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9
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Interareal coordination of columnar architectures during visual cortical development. Proc Natl Acad Sci U S A 2009; 106:17205-10. [PMID: 19805149 DOI: 10.1073/pnas.0901615106] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The formation of cortical columns is often conceptualized as a local process in which synaptic microcircuits confined to the volume of the emerging column are established and selectively refined. Many neurons, however, while wiring up locally are simultaneously building macroscopic circuits spanning widely distributed brain regions, such as different cortical areas or the two brain hemispheres. Thus, it is conceivable that interareal interactions shape the local column layout. Here we show that the columnar architectures of different areas of the cat visual cortex in fact develop in a coordinated manner, not adequately described as a local process. This is revealed by comparing the layouts of orientation columns (i) in left/right pairs of brain hemispheres and (ii) in areas V1 and V2 of individual brain hemispheres. Whereas the size of columns varied strongly within all areas considered, columns in different areas were typically closely matched in size if they were mutually connected. During development, we find that such mutually connected columns progressively become better matched in size as the late phase of the critical period unfolds. Our results suggest that one function of critical-period plasticity is to progressively coordinate the functional architectures of different cortical areas--even across hemispheres.
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10
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The role of feedback in visual masking and visual processing. Adv Cogn Psychol 2008; 3:125-52. [PMID: 20517504 PMCID: PMC2864985 DOI: 10.2478/v10053-008-0020-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Accepted: 03/06/2007] [Indexed: 11/20/2022] Open
Abstract
This paper reviews the potential role of feedback in visual masking, for and against. Our analysis reveals constraints for feedback mecha- nisms that limit their potential role in visual masking, and in all other general brain functions. We propose a feedforward model of visual masking, and provide a hypothesis to explain the role of feedback in visual masking and visual processing in general. We review the anato-my and physiology of feedback mechanisms, and propose that the massive ratio of feedback versus feedforward connections in the visual system may be explained solely by the critical need for top-down attentional modulation. We discuss the merits of visual masking as a tool to discover the neural correlates of consciousness, especially as compared to other popular illusions, such as binocular rivalry. Finally, we propose a new set of neurophysiological standards needed to establish whether any given neuron or brain circuit may be the neural substrate of awareness.
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11
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Angelucci A, Bressloff PC. Contribution of feedforward, lateral and feedback connections to the classical receptive field center and extra-classical receptive field surround of primate V1 neurons. PROGRESS IN BRAIN RESEARCH 2006; 154:93-120. [PMID: 17010705 DOI: 10.1016/s0079-6123(06)54005-1] [Citation(s) in RCA: 301] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
A central question in visual neuroscience is what circuits generate the responses of neurons in the primary visual cortex (V1). V1 neurons respond best to oriented stimuli of optimal size within their receptive field (RF) center. This size tuning is contrast dependent, i.e. a neuron's optimal stimulus size measured at high contrast (the high-contrast summation RF, or hsRF) is smaller than when measured using low-contrast stimuli (the low-contrast summation RF, or lsRF). Responses to stimuli in the RF center are usually suppressed by iso-oriented stimuli in the extra-classical RF surround. Iso-orientation surround suppression is fast and long range, extending well beyond the size of V1 cells' lsRF. Geniculocortical feedforward (FF), V1 lateral and extrastriate feedback (FB) connections to V1 could all contribute to generating the RF center and surround of V1 neurons. Studies on the spatio-temporal properties and functional organization of these connections can help disclose their specific contributions to the responses of V1 cells. These studies, reviewed in this chapter, have shown that FF afferents to V1 integrate signals within the hsRF of V1 cells; V1 lateral connections are commensurate with the size of the lsRF and may, thus, underlie contrast-dependent changes in spatial summation, and modulatory effects arising from the surround region closer to the RF center (the "near" surround). The spatial and temporal properties of lateral connections cannot account for the dimensions and onset latency of modulation arising from more distant regions of the surround (the "far" surround). Inter-areal FB connections to V1, instead, are commensurate with the full spatial range of center and surround responses, and show fast conduction velocity consistent with the short onset latency of modulation arising from the "far" surround. We review data showing that a subset of FB connections terminate in a patchy fashion in V1, and show modular and orientation specificity, consistent with their proposed role in orientation-specific center-surround interactions. We propose specific mechanisms by which each connection type contributes to the RF center and surround of V1 neurons, and implement these hypotheses into a recurrent network model. We show physiological data in support of the model's predictions, revealing that modulation from the "far" surround is not always suppressive, but can be facilitatory under specific stimulus conditions.
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Affiliation(s)
- Alessandra Angelucci
- Department of Ophthalmology and Visual Science, Moran Eye Center, University of Utah, 50 North Medical Drive, Salt Lake City, UT 84132, USA.
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Angelucci A, Bullier J. Reaching beyond the classical receptive field of V1 neurons: horizontal or feedback axons? ACTA ACUST UNITED AC 2004; 97:141-54. [PMID: 14766139 DOI: 10.1016/j.jphysparis.2003.09.001] [Citation(s) in RCA: 163] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
It is commonly assumed that the orientation-selective surround field of neurons in primary visual cortex (V1) is due to interactions provided solely by intrinsic long-range horizontal connections. We review evidence for and against this proposition and conclude that horizontal connections are too slow and cover too little visual field to subserve all the functions of suppressive surrounds of V1 neurons in the macaque monkey. We show that the extent of visual space covered by horizontal connections corresponds to the region of low contrast summation of the receptive field center mechanism. This region encompasses the classically defined receptive field center and the proximal surround. Beyond this region, feedback connections are the most likely substrate for surround suppression. We present evidence that inactivation of higher order areas leads to a major decrease in the strength of the suppressive surround of neurons in lower order areas, supporting the hypothesis that feedback connections play a major role in center-surround interactions.
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Affiliation(s)
- Alessandra Angelucci
- Department of Ophthalmology, Moran Eye Center, University of Utah, 50 North Medical Drive, Salt Lake City, UT 84132, USA.
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Alekseenko SV, Toporova SN, Makarov FN. Structure of reciprocal connections of visual cortical fields 17 and 18 in the cat. ACTA ACUST UNITED AC 2003; 33:707-10. [PMID: 14552539 DOI: 10.1023/a:1024469025734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Microiontophoretic application of horseradish peroxidase to individual columns in fields 17 and 18 of the cat cortex was used to identify the distribution by area and layer of retrograde labeled cells in both fields. After application of marker to fields 17 or 18, the area of labeled cells in field 17 (in the tangential plane) was extended and orientated along the projection of the horizontal meridian of the field of vision. The area of labeled cells in field 18 in these cases was orientated along the projections of the vertical meridian. Similar differences in the organization of the connections of fields 17 and 18 were seen in the projection zone of the central 10 degrees of the field of vision at different elevations. Thus, the spatial distributions of internal and external connections in each field coincide and their orientations in fields 17 and 18 are mutually perpendicular. It is suggested that field 17 performs the more detailed analysis of information on the horizontal components of an image and communicates this to field 18, while field 18 is responsible for the more detailed analysis of information about the vertical components of the same image, communicating this to field 17.
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Affiliation(s)
- S V Alekseenko
- Visual Physiology Laboratory and Interneuronal Connection Morphology Division, I. P. Pavlov Institute of Physiology, Russian Academy of Sciences, 6 Makarov Bank, 199034 St. Petersburg, Russia
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14
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Abstract
Contrast-dependent changes in spatial summation and contextual modulation of primary visual cortex (V1) neuron responses to stimulation of their receptive field reveal long-distance integration of visual signals within V1, well beyond the classical receptive field (cRF) of single neurons. To identify the cortical circuits mediating these long-distance computations, we have used a combination of anatomical and physiological recording methods to determine the spatial scale and retinotopic logic of intra-areal V1 horizontal connections and inter-areal feedback connections to V1. We have then compared the spatial scales of these connectional systems to the spatial dimensions of the cRF, spatial summation field (SF), and modulatory surround field of macaque V1 neurons. We find that monosynaptic horizontal connections within area V1 are of an appropriate spatial scale to mediate interactions within the SF of V1 neurons and to underlie contrast-dependent changes in SF size. Contrary to common beliefs, these connections cannot fully account for the dimensions of the surround field. The spatial scale of feedback circuits from extrastriate cortex to V1 is, instead, commensurate with the full spatial range of center-surround interactions. Thus these connections could represent an anatomical substrate for contextual modulation and global-to-local integration of visual signals. Feedback projections connect corresponding and equal-sized regions of the visual field in striate and extrastriate cortices and cover anisotropic parts of visual space, unlike V1 horizontal connections that are isotropic in the macaque. V1 isotropic connectivity demonstrates that anisotropic horizontal connections are not necessary to generate orientation selectivity. Anisotropic feedback connections may play a role in contour completion.
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Makarov FN, Granstrem EE, Markova LA. Morphological analysis of the cluster organization of corticocortical neurons in field 17 of the cat visual cortex. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2001; 31:359-61. [PMID: 11508483 DOI: 10.1023/a:1010472108704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- F N Makarov
- Laboratory for Central Nervous System Morphology I. P. Pavlov Institute of Physiology, Russian Academy of Sciences, St Petersburg
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16
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Rumberger A, Tyler CJ, Lund JS. Intra- and inter-areal connections between the primary visual cortex V1 and the area immediately surrounding V1 in the rat. Neuroscience 2001; 102:35-52. [PMID: 11226668 DOI: 10.1016/s0306-4522(00)00475-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We have qualitatively and quantitatively analysed the anatomical connections within and between rat primary visual cortex (V1) and the rim region surrounding area V1, using both ortho- and retrograde anatomical tracers (biotinylated dextran amine, biocytin, cholera toxin b subunit). From the analysis of the projection patterns, and with the assumption that single points in the rat visual cortex, as in other species, have projection fields made up of multiple patches of terminals, we have concluded that just two V1 recipient areas occupy the entire rim region: an anterolateral area, probably homologous with V2 in other mammals, previously named Oc2L, and a medial area, corresponding to Oc2M. A non-reciprocal projection from the anterolateral area to the medial area was identified. Small injections (300-600microm uptake zone diameter) of the anatomical tracers in area V1, or in the rim region, label orthograde intra-areal connections from each injection site to offset small patches. This is found in all regions of the rim and within at least the relatively expanded central dorsal field representation of V1. From the extent of these projections in V1 and the two rim regions, we have estimated that the neurons at the injection site send diverging laterally spreading projections to other neurons whose receptive fields share any part of the area included in the pooled receptive fields of the neurons at the injection site. Orthogradely labelled inter-areal feedforward projections from V1 to either rim region are estimated to diverge in their projections to neurons that share any part of the area of the pooled receptive fields of the V1 intra-areal connectional field of the same injection. The orthogradely labelled feedback projections to V1, from injection sites in either rim region, reach V1 neurons whose pooled receptive fields match those of the neurons in the rim injection site, i.e. with no divergence. Despite patchy anatomical connectional fields, our estimates indicate that visual space is represented continuously in the receptive fields of neurons postsynaptic to each intra- or inter-areal field of orthograde label. We suggest that, despite the absence of regularly mapped functions in rat V1 (e.g. regularly arranged orientation specificity), which in other species (e.g. primates and cats) relate to the patchy connectional patterns, the rat visual cortex intra- and inter-areal anatomical connections follow similar patterns and scaling factors to those in other species.
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Affiliation(s)
- A Rumberger
- Department of Visual Science, Institute of Ophthalmology, UCL, 11-43 Bath Street, EC1 V9EL, London, UK
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Hupé JM, James AC, Girard P, Bullier J. Response modulations by static texture surround in area V1 of the macaque monkey do not depend on feedback connections from V2. J Neurophysiol 2001; 85:146-63. [PMID: 11152715 DOI: 10.1152/jn.2001.85.1.146] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We analyzed the extracellular responses of 70 V1 neurons (recorded in 3 anesthetized macaque monkeys) to a single oriented line segment (or bar) placed within the cell classical receptive field (RF), or center of the RF. These responses could be modulated when rings of bars were placed entirely outside, but around the RF (the "near" surround region), as described in previous studies. Suppression was the main effect. The response was enhanced for 12 neurons when orthogonal bars in the surround were presented instead of bars having the same orientation as the center bar. This orientation contrast property is possibly involved in the mediation of perceptual pop-out. The enhancement was delayed compared with the onset of the response by about 40 ms. We also observed a suppression originating specifically from the flanks of the surround. This "side-inhibition," significant for nine neurons, was delayed by about 20 ms. We tested whether these center/surround interactions in V1 depend on feedback connections from area V2. V2 was inactivated by GABA injections. We used devices made of six micropipettes to inactivate the convergent zone from V2 to V1. We could reliably inactivate a 2- to 4-mm-wide region of V2. Inactivation of V2 had no effect on the center/surround interactions of V1 neurons, even those that were delayed. Therefore the center/surround interactions of V1 neurons that might be involved in pop-out do not appear to depend on feedback connections from V2, at least in the anesthetized monkey. We conclude that these properties are probably shaped by long-range connections within V1 or depend on other feedback connections. The main effect of V2 inactivation was a decrease of the response to the single bar for about 10% of V1 neurons. The decrease was delayed by <20 ms after the response onset. Even the earliest neurons to respond could be affected by the feedback from V2. Together with the results on feedback connections from MT (previous paper), these findings show that feedback connections potentiate the responses to stimulation of the RF center and are recruited very early for the treatment of visual information.
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Affiliation(s)
- J M Hupé
- Cerveau et Vision, Institut National de la Santé et de la Recherche Médicale U371, 69675 Bron Cedex, France.
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Martinez-Conde S, Cudeiro J, Grieve KL, Rodriguez R, Rivadulla C, Acuña C. Effects of feedback projections from area 18 layers 2/3 to area 17 layers 2/3 in the cat visual cortex. J Neurophysiol 1999; 82:2667-75. [PMID: 10561436 DOI: 10.1152/jn.1999.82.5.2667] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the absence of a direct geniculate input, area 17 cells in the cat are nevertheless able to respond to visual stimuli because of feedback connections from area 18. Anatomic studies have shown that, in the cat visual cortex, layer 5 of area 18 projects to layer 5 of area 17, and layers 2/3 of area 18 project to layers 2/3 of area 17. What is the specific role of these connections? Previous studies have examined the effect of area 18 layer 5 blockade on cells in area 17 layer 5. Here we examine whether the feedback connections from layers 2/3 of area 18 influence the orientation tuning and velocity tuning of cells in layers 2/3 of area 17. Experiments were carried out in anesthetized and paralyzed cats. We blocked reversibly a small region (300 microm radius) in layers 2/3 of area 18 by iontophoretic application of GABA and recorded simultaneously from cells in layers 2/3 of area 17 while stimulating with oriented sweeping bars. Area 17 cells showed either enhanced or suppressed visual responses to sweeping bars of various orientations and velocities during area 18 blockade. For most area 17 cells, orientation bandwidths remained unaltered, and we never observed visual responses during blockade that were absent completely in the preblockade condition. This suggests that area 18 layers 2/3 modulate visual responses in area 17 layers 2/3 without fundamentally altering their specificity.
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Affiliation(s)
- S Martinez-Conde
- Laboratorios de Neurociencia y Computacion Neuronal (asociados al Instituto Cajal-CSIC), Facultad de Medicina y Servicio Neurofisiologia Clinica-Complejo Hospitalario Universidad de Santiago de Compostela, Santiago de Compostela, Spain
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Schiltz C, Bodart JM, Dubois S, Dejardin S, Michel C, Roucoux A, Crommelinck M, Orban GA. Neuronal mechanisms of perceptual learning: changes in human brain activity with training in orientation discrimination. Neuroimage 1999; 9:46-62. [PMID: 9918727 DOI: 10.1006/nimg.1998.0394] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Using 15O-water 3D positron emission tomography, regional cerebral blood flow was measured twice in six human subjects: before and after extensive training in orientation discrimination. In each session subjects performed two orientation discrimination tasks, during which they discriminated the orientation of a grating at either the trained or untrained reference orientation, and a control task, during which they detected a randomly textured pattern. By comparing the discrimination to the detection tasks, we observed a main effect of task bilaterally in the posterior occipital cortex, extending into the left posterior fusiform gyrus and the right inferior occipital gyrus, bilaterally in the intraparietal sulcus, as well as in the cerebellum, thalamus, and brainstem. When we compared the activation pattern before and after the training period, all the changes observed were activity decreases. The nonspecific changes, which were not related to the orientation used during the training, were situated in the cerebellum and bilaterally in the extrastriate visual cortex. The orientation-specific changes, on the other hand, were restricted to the striate and extrastriate visual cortex, more precisely the right calcarine sulcus, the left lingual gyrus, the left middle occipital, and the right inferior occipital gyrus. These findings confirm our hypothesis concerning the existence of learning related changes at early levels of visual processing in human adults and suggest that mechanisms resulting in neuronal activity decreases might be involved in the present kind of learning.
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Affiliation(s)
- C Schiltz
- Laboratory of Neurophysiology, U.C.L., Brussels, Belgium
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