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Ye Z, Ding J, Tu Y, Zhang Q, Chen S, Yu H, Sun Q, Hua T. Suppression of top-down influence decreases both behavioral and V1 neuronal response sensitivity to stimulus orientations in cats. Front Behav Neurosci 2023; 17:1061980. [PMID: 36844652 PMCID: PMC9944033 DOI: 10.3389/fnbeh.2023.1061980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 01/24/2023] [Indexed: 02/11/2023] Open
Abstract
How top-down influence affects behavioral detection of visual signals and neuronal response sensitivity in the primary visual cortex (V1) remains poorly understood. This study examined both behavioral performance in stimulus orientation identification and neuronal response sensitivity to stimulus orientations in the V1 of cat before and after top-down influence of area 7 (A7) was modulated by non-invasive transcranial direct current stimulation (tDCS). Our results showed that cathode (c) but not sham (s) tDCS in A7 significantly increased the behavioral threshold in identifying stimulus orientation difference, which effect recovered after the tDCS effect vanished. Consistently, c-tDCS but not s-tDCS in A7 significantly decreased the response selectivity bias of V1 neurons for stimulus orientations, which effect could recover after withdrawal of the tDCS effect. Further analysis showed that c-tDCS induced reduction of V1 neurons in response selectivity was not resulted from alterations of neuronal preferred orientation, nor of spontaneous activity. Instead, c-tDCS in A7 significantly lowered the visually-evoked response, especially the maximum response of V1 neurons, which caused a decrease in response selectivity and signal-to-noise ratio. By contrast, s-tDCS exerted no significant effect on the responses of V1 neurons. These results indicate that top-down influence of A7 may enhance behavioral identification of stimulus orientations by increasing neuronal visually-evoked response and response selectivity in the V1.
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Affiliation(s)
- Zheng Ye
- College of Life sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Jian Ding
- College of Life sciences, Anhui Normal University, Wuhu, Anhui, China,School of Basic Medical, Wannan Medical College, Wuhu, Anhui, China
| | - Yanni Tu
- College of Life sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Qiuyu Zhang
- College of Life sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Shunshun Chen
- College of Life sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Hao Yu
- College of Life sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Qingyan Sun
- College of Life sciences, Anhui Normal University, Wuhu, Anhui, China
| | - Tianmiao Hua
- College of Life sciences, Anhui Normal University, Wuhu, Anhui, China,*Correspondence: Tianmiao Hua,
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Ding J, Ye Z, Xu F, Hu X, Yu H, Zhang S, Tu Y, Zhang Q, Sun Q, Hua T, Lu ZL. Effects of top-down influence suppression on behavioral and V1 neuronal contrast sensitivity functions in cats. iScience 2022; 25:103683. [PMID: 35059603 PMCID: PMC8760559 DOI: 10.1016/j.isci.2021.103683] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 11/16/2021] [Accepted: 12/20/2021] [Indexed: 02/09/2023] Open
Abstract
To explore the relative contributions of higher-order and primary visual cortex (V1) to visual perception, we compared cats' behavioral and V1 neuronal contrast sensitivity functions (CSF) and threshold versus external noise contrast (TvC) functions before and after top-down influence of area 7 (A7) was modulated with transcranial direct current stimulation (tDCS). We found that suppressing top-down influence of A7 with cathode-tDCS, but not sham-tDCS, reduced behavioral and neuronal contrast sensitivity in the same range of spatial frequencies and increased behavioral and neuronal contrast thresholds in the same range of external noise levels. The neuronal CSF and TvC functions were highly correlated with their behavioral counterparts both before and after the top-down suppression. Analysis of TvC functions using the Perceptual Template Model (PTM) indicated that top-down influence of A7 increased both behavioral and V1 neuronal contrast sensitivity by reducing internal additive noise and the impact of external noise. Top-down suppression lowers both behavioral and V1 neuronal CSF functions Top-down suppression raises both behavioral and V1 neuronal TvC functions The neuronal CSFs and TvCs are highly correlated with their behavioral counterparts Top-down influence lowers internal additive noise and impact of external noise in V1
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Affiliation(s)
- Jian Ding
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui 241000, China
| | - Zheng Ye
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui 241000, China
| | - Fei Xu
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui 241000, China
| | - Xiangmei Hu
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui 241000, China
| | - Hao Yu
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui 241000, China
| | - Shen Zhang
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui 241000, China
| | - Yanni Tu
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui 241000, China
| | - Qiuyu Zhang
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui 241000, China
| | - Qingyan Sun
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui 241000, China
| | - Tianmiao Hua
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui 241000, China
| | - Zhong-Lin Lu
- Divison of Arts and Sciences, NYU Shanghai, Shanghai 200122, China.,Center for Neural Science and Department of Psychology, New York University, New York, NY 10003, USA.,NYU-ECNU Institute of Brain and Cognitive Science, NYU Shanghai, Shanghai 200062, China
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Pan H, Zhang S, Pan D, Ye Z, Yu H, Ding J, Wang Q, Sun Q, Hua T. Characterization of Feedback Neurons in the High-Level Visual Cortical Areas That Project Directly to the Primary Visual Cortex in the Cat. Front Neuroanat 2021; 14:616465. [PMID: 33488364 PMCID: PMC7820340 DOI: 10.3389/fnana.2020.616465] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 12/04/2020] [Indexed: 12/17/2022] Open
Abstract
Previous studies indicate that top-down influence plays a critical role in visual information processing and perceptual detection. However, the substrate that carries top-down influence remains poorly understood. Using a combined technique of retrograde neuronal tracing and immunofluorescent double labeling, we characterized the distribution and cell type of feedback neurons in cat's high-level visual cortical areas that send direct connections to the primary visual cortex (V1: area 17). Our results showed: (1) the high-level visual cortex of area 21a at the ventral stream and PMLS area at the dorsal stream have a similar proportion of feedback neurons back projecting to the V1 area, (2) the distribution of feedback neurons in the higher-order visual area 21a and PMLS was significantly denser than in the intermediate visual cortex of area 19 and 18, (3) feedback neurons in all observed high-level visual cortex were found in layer II-III, IV, V, and VI, with a higher proportion in layer II-III, V, and VI than in layer IV, and (4) most feedback neurons were CaMKII-positive excitatory neurons, and few of them were identified as inhibitory GABAergic neurons. These results may argue against the segregation of ventral and dorsal streams during visual information processing, and support "reverse hierarchy theory" or interactive model proposing that recurrent connections between V1 and higher-order visual areas constitute the functional circuits that mediate visual perception. Also, the corticocortical feedback neurons from high-level visual cortical areas to the V1 area are mostly excitatory in nature.
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Affiliation(s)
- Huijun Pan
- College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Shen Zhang
- College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Deng Pan
- College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Zheng Ye
- College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Hao Yu
- College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Jian Ding
- College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Qin Wang
- College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Qingyan Sun
- College of Life Sciences, Anhui Normal University, Wuhu, China
| | - Tianmiao Hua
- College of Life Sciences, Anhui Normal University, Wuhu, China
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Shigihara Y, Hoshi H, Zeki S. Early visual cortical responses produced by checkerboard pattern stimulation. Neuroimage 2016; 134:532-539. [DOI: 10.1016/j.neuroimage.2016.03.078] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 01/20/2016] [Accepted: 03/31/2016] [Indexed: 11/25/2022] Open
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Pavlovskaya M, Soroker N, Bonneh YS, Hochstein S. Computing an Average When Part of the Population Is Not Perceived. J Cogn Neurosci 2015; 27:1397-411. [DOI: 10.1162/jocn_a_00791] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Abstract
The syndrome of unilateral spatial neglect (USN) after right-hemisphere damage is characterized by failure of salient left-sided stimuli to activate an orienting response, attract attention, and gain access to conscious awareness. The explicit failure processing left-sided visual information is not uniform, however, and patients seem to be more successful performing certain visual tasks than others. The source of this difference is still not clear. We focus on processing of visual scene statistical properties, asking whether, in computing the average size of an array of objects, USN patients give appropriate weight to objects on the left; disregard left-side objects entirely; or assign them an intermediate, lower weight, in accord with their tendency to neglect these objects. The interest in testing this question stems from a series of studies in healthy individuals that led Chong and Treisman [Chong, S. C., & Treisman, A. Statistical processing: Computing the average size in perceptual groups. Vision Research, 45, 891–900, 2005a; Chong, S. C., & Treisman, A. Attentional spread in the statistical processing of visual displays. Perception & Psychophysics, 67, 1–13, 2005b] to propose that processing of statistical properties (like the average size of visual scene elements) is carried out in parallel, with no need for serial allocation of focal attention to the different scene elements. Our results corroborate this suggestion, showing that objects in the left (“neglected”) hemispace contribute to average size computation, despite a marked imbalance in spatial distribution of attention, which leads to a reduced weight of left-side elements in the averaging computation. This finding sheds light on the nature of the impairment in USN and on basic mechanisms underlying statistical processing in vision. We confirm that statistical processing depends mainly on spread-attention mechanisms, which are largely spared in USN.
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Affiliation(s)
- Marina Pavlovskaya
- 1Loewenstein Rehabilitation Hospital, Raanana, Israel
- 2Tel-Aviv University
| | - Nachum Soroker
- 1Loewenstein Rehabilitation Hospital, Raanana, Israel
- 2Tel-Aviv University
| | | | - Shaul Hochstein
- 4Hebrew University, ELSC Safra Brain Research Center, Jerusalem, Israel
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Silvanto J. Why is "blindsight" blind? A new perspective on primary visual cortex, recurrent activity and visual awareness. Conscious Cogn 2014; 32:15-32. [PMID: 25263935 DOI: 10.1016/j.concog.2014.08.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 07/30/2014] [Accepted: 08/04/2014] [Indexed: 01/19/2023]
Abstract
The neuropsychological phenomenon of blindsight has been taken to suggest that the primary visual cortex (V1) plays a unique role in visual awareness, and that extrastriate activation needs to be fed back to V1 in order for the content of that activation to be consciously perceived. The aim of this review is to evaluate this theoretical framework and to revisit its key tenets. Firstly, is blindsight truly a dissociation of awareness and visual detection? Secondly, is there sufficient evidence to rule out the possibility that the loss of awareness resulting from a V1 lesion simply reflects reduced extrastriate responsiveness, rather than a unique role of V1 in conscious experience? Evaluation of these arguments and the empirical evidence leads to the conclusion that the loss of phenomenal awareness in blindsight may not be due to feedback activity in V1 being the hallmark awareness. On the basis of existing literature, an alternative explanation of blindsight is proposed. In this view, visual awareness is a "global" cognitive function as its hallmark is the availability of information to a large number of perceptual and cognitive systems; this requires inter-areal long-range synchronous oscillatory activity. For these oscillations to arise, a specific temporal profile of neuronal activity is required, which is established through recurrent feedback activity involving V1 and the extrastriate cortex. When V1 is lesioned, the loss of recurrent activity prevents inter-areal networks on the basis of oscillatory activity. However, as limited amount of input can reach extrastriate cortex and some extrastriate neuronal selectivity is preserved, computations involving comparison of neural firing rates within a cortical area remain possible. This enables "local" read-out from specific brain regions, allowing for the detection and discrimination of basic visual attributes. Thus blindsight is blind due to lack of "global" long-range synchrony, and it functions via "local" neural readout from extrastriate areas.
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Affiliation(s)
- Juha Silvanto
- University of Westminster, Faculty of Science and Technology, Department of Psychology, 309 Regent Street, W1B 2HW London, UK; Brain Research Unit, O.V. Lounasmaa Laboratory, School of Science, Aalto University, PO BOX 15100, 00076 Aalto, Finland.
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8
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Multisensory perceptual learning and sensory substitution. Neurosci Biobehav Rev 2014; 41:16-25. [DOI: 10.1016/j.neubiorev.2012.11.017] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 11/19/2012] [Accepted: 11/28/2012] [Indexed: 11/23/2022]
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Rusconi E, Dervinis M, Verbruggen F, Chambers CD. Critical time course of right frontoparietal involvement in mental number space. J Cogn Neurosci 2012; 25:465-83. [PMID: 23163421 DOI: 10.1162/jocn_a_00330] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Neuropsychological, neurophysiological, and neuroimaging studies suggest that right frontoparietal circuits may be necessary for the processing of mental number space, also known as the mental number line (MNL). Here we sought to specify the critical time course of three nodes that have previously been related to MNL processing: right posterior parietal cortex (rPPC), right FEF (rFEF), and right inferior frontal gyrus (rIFG). The effects of single-pulse TMS delivered at 120% distance-adjusted individual motor threshold were investigated in 21 participants, within a window of 0-400 msec (sampling interval = 33 msec) from the onset of a central digit (1-9, 5 excluded). Pulses were delivered in a random order and with equal probability at each time point, intermixed with noTMS trials. To analyze whether and when TMS interfered with MNL processing, we fitted bimodal Gaussian functions to the observed data and measured effects on changes in the Spatial-Numerical Association of Response Codes (SNARC) effect (i.e., an advantage for left- over right-key responses to small numbers and right- over left-key responses to large numbers) and in overall performance efficiency. We found that, during magnitude judgment with unimanual key-press responses, TMS reduced the SNARC effect in the earlier period of the fitted functions (∼25-60 msec) when delivered over rFEF (small and large numbers) and rIFG (small numbers); TMS further reduced the SNARC effect for small numbers in a later period when delivered to rFEF (∼200 msec). In contrast, TMS of rPPC did not interfere with the SNARC effect but generally reduced performance for small numbers and enhanced it for large numbers, thus producing a pattern reminiscent of "neglect" in mental number space. Our results confirm the causal role of an intact right frontoparietal network in the processing of mental number space. They also indicate that rPPC is specifically tied to explicit number magnitude processing and that rFEF and rIFG contribute to interfacing mental visuospatial codes with lateralized response codes. Overall, our findings suggest that both ventral and dorsal frontoparietal circuits are causally involved and functionally connected in the mapping of numbers to space.
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Affiliation(s)
- Elena Rusconi
- Department of Neurosciences, Section of Physiology, University of Parma, Via Volturno 39/E, I-43100 Parma, Italy.
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Cattaneo Z, Bona S, Silvanto J. Cross-adaptation combined with TMS reveals a functional overlap between vision and imagery in the early visual cortex. Neuroimage 2012; 59:3015-20. [DOI: 10.1016/j.neuroimage.2011.10.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 09/22/2011] [Accepted: 10/08/2011] [Indexed: 10/16/2022] Open
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Amihai I, Deouell L, Bentin S. Conscious awareness is necessary for processing race and gender information from faces. Conscious Cogn 2011; 20:269-79. [PMID: 20843704 PMCID: PMC3015017 DOI: 10.1016/j.concog.2010.08.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 08/14/2010] [Accepted: 08/19/2010] [Indexed: 11/30/2022]
Abstract
Previous studies suggested that emotions can be correctly interpreted from facial expressions in the absence of conscious awareness of the face. Our goal was to explore whether subordinate information about a face's gender and race could also become available without awareness of the face. Participants classified the race or the gender of unfamiliar faces that were ambiguous with regard to these dimensions. The ambiguous faces were preceded by face-images that unequivocally represented gender and race, rendered consciously invisible by simultaneous continuous-flash-suppression. The classification of ambiguous faces was biased away from the category of the adaptor only when it was consciously visible. The duration of subjective visibility correlated with the aftereffect strength. Moreover, face identity was consequential only if consciously perceived. These results suggest that while conscious awareness is not needed for basic level categorization, it is needed for subordinate categorization. Emotional information might be unique in this respect.
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Affiliation(s)
- Ido Amihai
- Department of Neurobiology, The Hebrew University of Jerusalem, Israel
| | - Leon Deouell
- Department of Psychology, The Hebrew University of Jerusalem, Israel
- Interdisciplinary Center for Neural Computation, The Hebrew University of Jerusalem, Israel
| | - Shlomo Bentin
- Department of Psychology, The Hebrew University of Jerusalem, Israel
- Interdisciplinary Center for Neural Computation, The Hebrew University of Jerusalem, Israel
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12
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Posterior parietal cortex mediates encoding and maintenance processes in change blindness. Neuropsychologia 2010; 48:1063-70. [DOI: 10.1016/j.neuropsychologia.2009.12.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 10/17/2009] [Accepted: 12/05/2009] [Indexed: 11/23/2022]
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13
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Ishizu T, Ayabe T, Kojima S. Temporal dissociation of global and local features by hierarchy of vision. Int J Neurosci 2009; 119:373-83. [PMID: 19116844 DOI: 10.1080/00207450802540524] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Most objects in our environment are organized hierarchically with a global whole embedding its local parts, but the way we recognize these features remains unclear. Using a visual masking paradigm, we examined the temporal dissociation between global and local feature as proposed in Reverse Hierarchy Theory, RHT (Ahissar & Hochstein, 2000), where global and local information are assumed to be processed, respectively, by feed-forward and feedback systems. We found that in a long Stimulus Onset Asynchrony (SOA) condition, both global and local information were recognized adequately. However, in a short SOA condition, global information was recognized correctly while local recognition was critically disrupted. Consistent with RHT, it is suggested that local information is processed in a feedback system; this processing is then interrupted by the mask stimulus presented later at the primary visual area. Global information, by contrast, is transferred via a feed-forward system, and is not disrupted by the mask.
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Affiliation(s)
- Tomohiro Ishizu
- Department of Psychology, Graduate School of Human Relations, Keio University, Mita, Minato-ku, Tokyo, Japan.
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14
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Bókkon I, D’Angiulli A. Emergence and transmission of visual awareness through optical coding in the brain: A redox molecular hypothesis on visual mental imagery. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.bihy.2009.01.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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15
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Ishizu T, Ayabe T, Kojima S. Configurational factors in the perception of faces and non-facial objects: an ERP study. Int J Neurosci 2008; 118:955-66. [PMID: 18569153 DOI: 10.1080/00207450701769398] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
During the viewing of human faces, it is easier to recognize detailed features if the face is presented in an unusual configuration; for example, a split face. The present study used electroencephalography to investigate the brain activity elicited in response to a neutral, inverted, and split face and compared this to the activity produced in response to a non-facial stimulus (a clock). Results showed that the N170 response amplitude was larger and its latency longer during recognition of split and inverted faces as compared to a normal face, whereas no amplitude change was seen for the different clock configurations. However, for the P300 component, larger amplitudes were observed in both the face and the object condition. Taken together, the results suggest that unusual human face presentations are detected at earlier stages than unusual object presentations.
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Affiliation(s)
- Tomohiro Ishizu
- Department of Psychology, Graduate School of Human Relations, Keio University, Tokyo, Japan.
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16
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Diamant E. Unveiling the mystery of visual information processing in human brain. Brain Res 2008; 1225:171-8. [DOI: 10.1016/j.brainres.2008.05.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2008] [Revised: 04/05/2008] [Accepted: 05/08/2008] [Indexed: 01/16/2023]
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Juan CH, Muggleton NG, Tzeng OJL, Hung DL, Cowey A, Walsh V. Segregation of visual selection and saccades in human frontal eye fields. Cereb Cortex 2008; 18:2410-5. [PMID: 18326522 DOI: 10.1093/cercor/bhn001] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The premotor theory of attention suggests that target processing and generation of a saccade to the target are interdependent. Temporally precise transcranial magnetic stimulation (TMS) was delivered over the human frontal eye fields, the area most frequently associated with the premotor theory in association with eye movements, while subjects performed a visually instructed pro-/antisaccade task. Visual analysis and saccade preparation were clearly separated in time, as indicated by 2 distinct time points of TMS delivery that resulted in elevated saccade latencies. These results show that visual analysis and saccade preparation, although frequently enacted together, are dissociable processes.
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Affiliation(s)
- C-H Juan
- Institute of Cognitive Neuroscience, National Central University, Jhongli 320, Taiwan.
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18
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Supèr H, Lamme VAF. Altered figure-ground perception in monkeys with an extra-striate lesion. Neuropsychologia 2007; 45:3329-34. [PMID: 17692346 DOI: 10.1016/j.neuropsychologia.2007.07.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 07/03/2007] [Accepted: 07/04/2007] [Indexed: 11/24/2022]
Abstract
The visual system binds and segments the elements of an image into coherent objects and their surroundings. Recent findings demonstrate that primary visual cortex is involved in this process of figure-ground organization. In the primary visual cortex the late part of a neural response to a stimulus correlates with figure-ground segregation and perception. Such a late onset indicates an involvement of feedback projections from higher visual areas. To investigate the possible role of feedback in figure-ground perception we removed dorsal extra-striate areas of the monkey visual cortex. The findings show that figure-ground perception is reduced when the figure is presented in the lesioned hemifield and perception is normal when the figure appeared in the intact hemifield. In conclusion, our observations show the importance for recurrent processing in visual perception.
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Affiliation(s)
- Hans Supèr
- Institucio Catalana de Recerca i Estudis Avancats & Dept. Psicologia Basica, Facultad de Psicologia, Universidad de Barcelona, Passeig de la Vall d' Hebron 171, 08035 Barcelona, Spain.
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19
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Murphey DK, Maunsell JHR. Behavioral detection of electrical microstimulation in different cortical visual areas. Curr Biol 2007; 17:862-7. [PMID: 17462895 PMCID: PMC2034326 DOI: 10.1016/j.cub.2007.03.066] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Revised: 03/03/2007] [Accepted: 03/29/2007] [Indexed: 11/18/2022]
Abstract
The extent to which areas in the visual cerebral cortex differ in their ability to support perceptions has been the subject of considerable speculation. Experiments examining the activity of individual neurons have suggested that activity in later stages of the visual cortex is more closely linked to perception than that in earlier stages [1-9]. In contrast, results from functional imaging, transcranial magnetic stimulation, and lesion studies have been interpreted as showing that earlier stages are more closely coupled to perception [10-15]. We examined whether neuronal activity in early and later stages differs in its ability to support detectable signals by measuring behavioral thresholds for detecting electrical microstimulation in different cortical areas in two monkeys. By training the animals to perform a two-alternative temporal forced-choice task, we obtained criterion-free thresholds from five visual areas--V1, V2, V3A, MT, and the inferotemporal cortex. Every site tested yielded a reliable threshold. Thresholds varied little within and between visual areas, rising gradually from early to later stages. We similarly found no systematic differences in the slopes of the psychometric detection functions from different areas. These results suggest that neuronal signals of similar magnitude evoked in any part of visual cortex can generate percepts.
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Affiliation(s)
- Dona K Murphey
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
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20
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Jiang Y, Zhou K, He S. Human visual cortex responds to invisible chromatic flicker. Nat Neurosci 2007; 10:657-62. [PMID: 17396122 DOI: 10.1038/nn1879] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2007] [Accepted: 02/21/2007] [Indexed: 11/08/2022]
Abstract
When two isoluminant colors alternate at frequencies of 25 Hz or higher, observers perceive only one fused color. Chromatic flicker beyond the fusion frequency induces flicker adaptation in human observers and stimulates monkey V1 neurons. Here we use functional magnetic resonance imaging (fMRI) to show that many human visual cortical areas, with the exception of VO, can distinguish between fused chromatic flicker and its matched nonflickering control. This result supports the existence of significant intracortical temporal filtering of high-frequency chromatic information. The result also suggests that a considerable difference in cortical activation in many visual cortical areas does not necessarily lead to different conscious experiences.
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Affiliation(s)
- Yi Jiang
- Department of Psychology, University of Minnesota, 75 E. River Rd., Minneapolis, Minnesota 55455, USA
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Abstract
Every day we shift our gaze about 150.000 times mostly without noticing it. The direction of these gaze shifts are not random but directed by sensory information and internal factors. After each movement the eyes hold still for a brief moment so that visual information at the center of our gaze can be processed in detail. This means that visual information at the saccade target location is sufficient to accurately guide the gaze shift but yet is not sufficiently processed to be fully perceived. In this paper I will discuss the possible role of activity in the primary visual cortex (V1), in particular figure-ground activity, in oculo-motor behavior. Figure-ground activity occurs during the late response period of V1 neurons and correlates with perception. The strength of figure-ground responses predicts the direction and moment of saccadic eye movements. The superior colliculus, a gaze control center that integrates visual and motor signals, receives direct anatomical connections from V1. These projections may convey the perceptual information that is required for appropriate gaze shifts. In conclusion, figure-ground activity in V1 may act as an intermediate component linking visual and motor signals.
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Affiliation(s)
- Hans Supèr
- ICREA & Department Basic Psychology, Faculty of Psychology, University of Barcelona (UB), Pg. Vall d'Hebron 171, 08035 Barcelona, Spain.
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22
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Supèr H, Lamme VAF. Strength of figure-ground activity in monkey primary visual cortex predicts saccadic reaction time in a delayed detection task. Cereb Cortex 2006; 17:1468-75. [PMID: 16920884 DOI: 10.1093/cercor/bhl058] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
When and where are decisions made? In the visual system a saccade, which is a fast shift of gaze toward a target in the visual scene, is the behavioral outcome of a decision. Current neurophysiological data and reaction time models show that saccadic reaction times are determined by a build-up of activity in motor-related structures, such as the frontal eye fields. These structures depend on the sensory evidence of the stimulus. Here we use a delayed figure-ground detection task to show that late modulated activity in the visual cortex (V1) predicts saccadic reaction time. This predictive activity is part of the process of figure-ground segregation and is specific for the saccade target location. These observations indicate that sensory signals are directly involved in the decision of when and where to look.
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Affiliation(s)
- Hans Supèr
- ICREA & Dep. Psicología Básica, Facultad de Psicología, Universidad de Barcelona, 08035 Barcelona, Spain.
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23
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Cudeiro J, Sillito AM. Looking back: corticothalamic feedback and early visual processing. Trends Neurosci 2006; 29:298-306. [PMID: 16712965 DOI: 10.1016/j.tins.2006.05.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Revised: 02/06/2006] [Accepted: 05/02/2006] [Indexed: 11/30/2022]
Abstract
Although once regarded as a simple sensory relay on the way to the cortex, it is increasingly apparent that the thalamus has a role in the ongoing moment-by-moment processing of sensory input and in cognition. This involves extensive corticofugal feedback connections and the interplay of these with the local thalamic circuitry and the other converging inputs. Here, using the feline visual system as the primary model, some of the latest developments in this field are reviewed and placed in the perspective of an integrated view of system function. Cortical feedback mediated by ionotropic and metabotropic glutamate receptors, and effects mediated by the neuromodulator nitric oxide, all have a role in integrating the thalamic mechanism into the cortical circuit. The essential point is that the perspective of higher-level sensory mechanisms shifts and modulates the thalamic circuitry in ways that optimize abstraction of a meaningful representation of the external world. This review is part of the TINS special issue on The Neural Substrates of Cognition.
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Affiliation(s)
- Javier Cudeiro
- NEUROcom (Neuroscience and Motor Control Group), Department of Medicine, University of A Coruña, Campus de Oza, 15006 A Coruña, Spain.
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24
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Rosenthal O, Behrmann M. Acquiring long-term representations of visual classes following extensive extrastriate damage. Neuropsychologia 2006; 44:799-815. [PMID: 16137724 DOI: 10.1016/j.neuropsychologia.2005.07.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2005] [Revised: 06/20/2005] [Accepted: 07/20/2005] [Indexed: 11/15/2022]
Abstract
Different areas of human visual cortex are thought to play different roles in the learning of visual information: whereas in low/intermediate cortical areas, plasticity may be manifested by enhanced selectivity to learned visual features, in higher-level areas, plasticity may result in generalization and development of tolerance to degraded versions of the learned stimuli. The most effective tolerance to degraded information is presumably achieved in the case of cooperation between the different forms of plasticity. Whether this tolerance to degraded information also applies when the visual input is degraded as a result of a lesion to lower levels of the visual system remains an open question. To address this, we studied visual classification learning in a patient with an extensive bilateral lesion affecting intermediate/low-level visual areas but sparing higher-level areas. Despite difficulty in perceiving the stimuli, the patient learned to classify them, albeit not as quickly as control participants. Moreover, the patient's learning was maintained over the long term and was accompanied by improved discrimination of individual stimuli. These findings demonstrate that degraded output from lesioned, lower areas can be exploited in the service of a new visual task and the results likely implicate a combination of bottom-up and top-down processing during visual learning.
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Affiliation(s)
- Orna Rosenthal
- UCLA, Department of Psychology, 7531 Franz Hall, UCLA, Los Angeles, CA 90095, USA.
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25
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Abstract
Perceptual learning can be defined as practice-induced improvement in the ability to perform specific perceptual tasks. We previously proposed the Reverse Hierarchy Theory as a unifying concept that links behavioral findings of visual learning with physiological and anatomical data. Essentially, it asserts that learning is a top-down guided process, which begins at high-level areas of the visual system, and when these do not suffice, progresses backwards to the input levels, which have a better signal-to-noise ratio. This simple concept has proved powerful in explaining a broad range of findings, including seemingly contradicting data. We now extend this concept to describe the dynamics of skill acquisition and interpret recent behavioral and electrophysiological findings.
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Affiliation(s)
- Merav Ahissar
- Department of Psychology and Interdisciplinary Center for Neural Computation, Hebrew University, Jerusalem 91905, Israel.
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