51
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Abstract
Decisions are often made by accumulating evidence for and against the alternatives. The momentary evidence represented by sensory neurons is accumulated by downstream structures to form a decision variable, linking the evolving decision to the formation of a motor plan. When decisions are communicated by eye movements, neurons in the lateral intraparietal area (LIP) represent the accumulation of evidence bearing on the potential targets for saccades. We now show that reach-related neurons from the medial intraparietal area (MIP) exhibit a gradual modulation of their firing rates consistent with the representation of an evolving decision variable. When decisions were communicated by saccades instead of reaches, decision-related activity was attenuated in MIP, whereas LIP neurons were active while monkeys communicated decisions by saccades or reaches. Thus, for decisions communicated by a hand movement, a parallel flow of sensory information is directed to parietal areas MIP and LIP during decision formation.
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52
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Erlich JC, Brunton BW, Duan CA, Hanks TD, Brody CD. Distinct effects of prefrontal and parietal cortex inactivations on an accumulation of evidence task in the rat. eLife 2015; 4:e05457. [PMID: 25869470 PMCID: PMC4392479 DOI: 10.7554/elife.05457] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 03/01/2015] [Indexed: 12/20/2022] Open
Abstract
Numerous brain regions have been shown to have neural correlates of gradually accumulating evidence for decision-making, but the causal roles of these regions in decisions driven by accumulation of evidence have yet to be determined. Here, in rats performing an auditory evidence accumulation task, we inactivated the frontal orienting fields (FOF) and posterior parietal cortex (PPC), two rat cortical regions that have neural correlates of accumulating evidence and that have been proposed as central to decision-making. We used a detailed model of the decision process to analyze the effect of inactivations. Inactivation of the FOF induced substantial performance impairments that were quantitatively best described as an impairment in the output pathway of an evidence accumulator with a long integration time constant (>240 ms). In contrast, we found a minimal role for PPC in decisions guided by accumulating auditory evidence, even while finding a strong role for PPC in internally-guided decisions.
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Affiliation(s)
- Jeffrey C Erlich
- NYU-ECNU Institute of Brain and Cognitive Science, NYU Shanghai, Shanghai, China
- Princeton Neuroscience Institute, Department of Molecular Biology, Princeton University, Princeton, United States
| | - Bingni W Brunton
- Princeton Neuroscience Institute, Department of Molecular Biology, Princeton University, Princeton, United States
- Department of Biology, UW Institute of Neuroengineering, University of Washington, Seattle, United States
| | - Chunyu A Duan
- Princeton Neuroscience Institute, Department of Molecular Biology, Princeton University, Princeton, United States
| | - Timothy D Hanks
- Princeton Neuroscience Institute, Department of Molecular Biology, Princeton University, Princeton, United States
| | - Carlos D Brody
- Princeton Neuroscience Institute, Department of Molecular Biology, Princeton University, Princeton, United States
- Howard Hughes Medical Institute, Princeton University, Princeton, United States
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53
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Differential dynamics of spatial attention, position, and color coding within the parietofrontal network. J Neurosci 2015; 35:3174-89. [PMID: 25698752 DOI: 10.1523/jneurosci.2370-14.2015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Despite an ever growing knowledge on how parietal and prefrontal neurons encode low-level spatial and color information or higher-level information, such as spatial attention, an understanding of how these cortical regions process neuronal information at the population level is still missing. A simple assumption would be that the function and temporal response profiles of these neuronal populations match that of its constituting individual cells. However, several recent studies suggest that this is not necessarily the case and that the single-cell approach overlooks dynamic changes in how information is distributed over the neuronal population. Here, we use a time-resolved population pattern analysis to explore how spatial position, spatial attention and color information are differentially encoded and maintained in the macaque monkey prefrontal (frontal eye fields) and parietal cortex (lateral intraparietal area). Overall, our work brings about three novel observations. First, we show that parietal and prefrontal populations operate in two distinct population regimens for the encoding of sensory and cognitive information: a stationary mode and a dynamic mode. Second, we show that the temporal dynamics of a heterogeneous neuronal population brings about complementary information to that of its functional subpopulations. Thus, both need to be investigated in parallel. Last, we show that identifying the neuronal configuration in which a neuronal population encodes given information can serve to reveal this same information in a different context. All together, this work challenges common views on neural coding in the parietofrontal network.
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54
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Chang SWC, Calton JL, Lawrence BM, Dickinson AR, Snyder LH. Region-Specific Summation Patterns Inform the Role of Cortical Areas in Selecting Motor Plans. Cereb Cortex 2015; 26:2154-66. [PMID: 25778345 DOI: 10.1093/cercor/bhv047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Given an instruction regarding which effector to move and what location to move to, simply adding the effector and spatial signals together will not lead to movement selection. For this, a nonlinearity is required. Thresholds, for example, can be used to select a particular response and reject others. Here we consider another useful nonlinearity, a supralinear multiplicative interaction. To help select a motor plan, spatial and effector signals could multiply and thereby amplify each other. Such an amplification could constitute one step within a distributed network involved in response selection, effectively boosting one response while suppressing others. We therefore asked whether effector and spatial signals sum supralinearly for planning eye versus arm movements from the parietal reach region (PRR), the lateral intraparietal area (LIP), the frontal eye field (FEF), and a portion of area 5 (A5) lying just anterior to PRR. Unlike LIP neurons, PRR, FEF, and, to a lesser extent, A5 neurons show a supralinear interaction. Our results suggest that selecting visually guided eye versus arm movements is likely to be mediated by PRR and FEF but not LIP.
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Affiliation(s)
- Steve W C Chang
- Department of Psychology, Yale University, New Haven, CT 06511, USA Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Jeffrey L Calton
- Department of Psychology, Sacramento State University, Sacramento, CA 95819, USA
| | - Bonnie M Lawrence
- Department of Psychology, New York University, New York, NY 10003, USA
| | - Anthony R Dickinson
- Department of Anatomy and Neurobiology, Washington University in St Louis School of Medicine, St Louis, MO 63110, USA
| | - Lawrence H Snyder
- Department of Anatomy and Neurobiology, Washington University in St Louis School of Medicine, St Louis, MO 63110, USA
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55
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Abstract
Parietal cortex is central to spatial cognition. Lesions of parietal cortex often lead to hemispatial neglect, an impairment of choices of targets in space. It has been unclear whether parietal cortex implements target choice at the general cognitive level, or whether parietal cortex subserves the choice of targets of particular actions. To address this question, monkeys engaged in choice tasks in two distinct action contexts--eye movements and arm movements. We placed focused reversible lesions into specific parietal circuits using the GABAA receptor agonist muscimol and validated the lesion placement using MRI. We found that lesions on the lateral bank of the intraparietal sulcus [lateral intraparietal area (LIP)] specifically biased choices made using eye movements, whereas lesions on the medial bank of the intraparietal sulcus [parietal reach region (PRR)] specifically biased choices made using arm movements. This double dissociation suggests that target choice is implemented in dedicated parietal circuits in the context of specific actions. This finding emphasizes a motor role of parietal cortex in spatial choice making and contributes to our understanding of hemispatial neglect.
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56
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Abstract
Humans and other animals routinely encounter visual stimuli that indicate whether future reward delivery depends upon the identity or location of a stimulus, or the performance of a particular action. These reinforcement contingencies can influence how much attention is directed toward a stimulus. Neurons in the primate amygdala encode information about the association between visual stimuli and reinforcement as well as about the location of reward-predictive stimuli. Amygdala neural activity also predicts variability in spatial attention. In principle, the spatial properties of amygdala neurons may be present independent of spatial attention allocation. Alternatively, the encoding of spatial information may require attention. We trained monkeys to perform tasks that engaged spatial attention to varying degrees to understand the genesis of spatial processing in the amygdala. During classical conditioning tasks, conditioned stimuli appeared at different locations; amygdala neurons responded selectively to the location of stimuli. These spatial signals diminished rapidly upon stimulus disappearance and were unrelated to selectivity for expected reward. In contrast, spatial selectivity was sustained in time when monkeys performed a delayed saccade task that required sustained spatial attention. This temporally extended spatial signal was correlated with signals encoding reward expectation. Furthermore, variability in firing rates was correlated with variability in spatial attention, as measured by reaction time. These results reveal two types of spatial signals in the amygdala: one that is tied to initial visual responses and a second that reflects coordination between spatial and reinforcement information and that relates to the engagement of spatial attention.
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57
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Premereur E, Van Dromme IC, Romero MC, Vanduffel W, Janssen P. Effective connectivity of depth-structure-selective patches in the lateral bank of the macaque intraparietal sulcus. PLoS Biol 2015; 13:e1002072. [PMID: 25689048 PMCID: PMC4331519 DOI: 10.1371/journal.pbio.1002072] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 01/09/2015] [Indexed: 12/04/2022] Open
Abstract
Extrastriate cortical areas are frequently composed of subpopulations of neurons encoding specific features or stimuli, such as color, disparity, or faces, and patches of neurons encoding similar stimulus properties are typically embedded in interconnected networks, such as the attention or face-processing network. The goal of the current study was to examine the effective connectivity of subsectors of neurons in the same cortical area with highly similar neuronal response properties. We first recorded single- and multi-unit activity to identify two neuronal patches in the anterior part of the macaque intraparietal sulcus (IPS) showing the same depth structure selectivity and then employed electrical microstimulation during functional magnetic resonance imaging in these patches to determine the effective connectivity of these patches. The two IPS subsectors we identified-with the same neuronal response properties and in some cases separated by only 3 mm-were effectively connected to remarkably distinct cortical networks in both dorsal and ventral stream in three macaques. Conversely, the differences in effective connectivity could account for the known visual-to-motor gradient within the anterior IPS. These results clarify the role of the anterior IPS as a pivotal brain region where dorsal and ventral visual stream interact during object analysis. Thus, in addition to the anatomical connectivity of cortical areas and the properties of individual neurons in these areas, the effective connectivity provides novel key insights into the widespread functional networks that support behavior.
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Affiliation(s)
- Elsie Premereur
- Lab. voor Neuro- en Psychofysiologie, KU Leuven, Leuven, Belgium
| | | | - Maria C. Romero
- Lab. voor Neuro- en Psychofysiologie, KU Leuven, Leuven, Belgium
| | - Wim Vanduffel
- Lab. voor Neuro- en Psychofysiologie, KU Leuven, Leuven, Belgium
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
- Department of Radiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Peter Janssen
- Lab. voor Neuro- en Psychofysiologie, KU Leuven, Leuven, Belgium
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58
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Zirnsak M, Moore T. Saccades and shifting receptive fields: anticipating consequences or selecting targets? Trends Cogn Sci 2014; 18:621-8. [PMID: 25455690 DOI: 10.1016/j.tics.2014.10.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 10/06/2014] [Accepted: 10/07/2014] [Indexed: 11/28/2022]
Abstract
Saccadic eye movements cause frequent and substantial displacements of the retinal image, but those displacements go unnoticed. It has been widely assumed that this perceived stability emerges from the shifting of visual receptive fields from their current, presaccadic locations to their future, postsaccadic locations in anticipation of the retinal consequences of saccades. Although evidence consistent with this anticipatory remapping has accumulated over the years, more recent work suggests an alternative view. In this opinion article, we examine the evidence of presaccadic receptive field shifts and their relationship to the perceptual changes that accompany saccades. We argue that both reflect the selection of targets for saccades rather than the anticipation of a displaced retinal image.
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Affiliation(s)
- Marc Zirnsak
- Department of Neurobiology, and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Tirin Moore
- Department of Neurobiology, and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
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59
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Steinmetz NA, Moore T. Eye movement preparation modulates neuronal responses in area V4 when dissociated from attentional demands. Neuron 2014; 83:496-506. [PMID: 25033188 DOI: 10.1016/j.neuron.2014.06.014] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2014] [Indexed: 11/26/2022]
Abstract
We examined whether the preparation of saccadic eye movements, when behaviorally dissociated from covert attention, modulates activity within visual cortex. We measured single-neuron and local field potential (LFP) responses to visual stimuli in area V4 while monkeys covertly attended a stimulus at one location and prepared saccades to a potential target at another. In spite of the irrelevance of visual information at the saccade target, visual activity at that location was modulated at least as much as, and often more than, activity at the covertly attended location. Modulations of activity at the attended and saccade target locations were qualitatively similar and included increased response magnitude, stimulus selectivity, and spiking reliability, as well as increased gamma and decreased low-frequency power of LFPs. These results demonstrate that saccade preparation is sufficient to modulate visual cortical representations and suggest that the interrelationship of oculomotor and attention-related mechanisms extends to posterior visual cortex.
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Affiliation(s)
- Nicholas A Steinmetz
- Department of Neurobiology and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Tirin Moore
- Department of Neurobiology and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
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60
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Patel GH, Kaplan DM, Snyder LH. Topographic organization in the brain: searching for general principles. Trends Cogn Sci 2014; 18:351-63. [PMID: 24862252 PMCID: PMC4074559 DOI: 10.1016/j.tics.2014.03.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 03/27/2014] [Accepted: 03/28/2014] [Indexed: 12/12/2022]
Abstract
The neurons comprising many cortical areas have long been known to be arranged topographically such that nearby neurons have receptive fields at nearby locations in the world. Although this type of organization may be universal in primary sensory and motor cortex, in this review we demonstrate that associative cortical areas may not represent the external world in a complete and continuous fashion. After reviewing evidence for novel principles of topographic organization in macaque lateral intraparietal area (LIP) - one of the most-studied associative areas in the parietal cortex - we explore the implications of these new principles for brain function.
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Affiliation(s)
- Gaurav H Patel
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA; New York State Psychiatric Institute, New York, NY 10032, USA.
| | - David M Kaplan
- Department of Cognitive Science, Macquarie University, Sydney, NSW 2109, Australia
| | - Lawrence H Snyder
- Department of Anatomy and Neurobiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
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61
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Nishida S, Tanaka T, Ogawa T. Transition of target-location signaling in activity of macaque lateral intraparietal neurons during delayed-response visual search. J Neurophysiol 2014; 112:1516-27. [PMID: 24966299 DOI: 10.1152/jn.00262.2014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neurons in the lateral intraparietal area (LIP) are involved in signaling the location of behaviorally relevant objects during visual discrimination and working memory maintenance. Although previous studies have examined these cognitive processes separately, they often appear as inseparable sequential processes in real-life situations. Little is known about how the neural representation of the target location is altered when both cognitive processes are continuously required for executing a task. We investigated this issue by recording single-unit activity from LIP of monkeys performing a delayed-response visual search task in which they were required to discriminate the target from distractors in the stimulus period, remember the location at which the extinguished target had been presented in the delay period, and make a saccade to that location in the response period. Target-location signaling was assessed using response modulations contingent on whether the target location was inside or opposite the receptive field. Although the population-averaged response modulation was consistent and changed only slightly during a trial, the across-neuron pattern of response modulations showed a marked and abrupt change around 170 ms after stimulus offset due to concurrent changes in the response modulations of a subset of LIP neurons, which manifested heterogeneous patterns of activity changes during the task. Our findings suggest that target-location signaling by the across-neuron pattern of LIP activity discretely changes after the stimulus disappearance under conditions that continuously require visual discrimination and working memory to perform a single behavioral task.
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Affiliation(s)
- Satoshi Nishida
- Kokoro Research Center, Kyoto University, Kyoto, Japan; and Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tomohiro Tanaka
- Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tadashi Ogawa
- Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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62
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Andersen RA, Andersen KN, Hwang EJ, Hauschild M. Optic ataxia: from Balint's syndrome to the parietal reach region. Neuron 2014; 81:967-983. [PMID: 24607223 DOI: 10.1016/j.neuron.2014.02.025] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2014] [Indexed: 01/10/2023]
Abstract
Optic ataxia is a high-order deficit in reaching to visual goals that occurs with posterior parietal cortex (PPC) lesions. It is a component of Balint's syndrome that also includes attentional and gaze disorders. Aspects of optic ataxia are misreaching in the contralesional visual field, difficulty preshaping the hand for grasping, and an inability to correct reaches online. Recent research in nonhuman primates (NHPs) suggests that many aspects of Balint's syndrome and optic ataxia are a result of damage to specific functional modules for reaching, saccades, grasp, attention, and state estimation. The deficits from large lesions in humans are probably composite effects from damage to combinations of these functional modules. Interactions between these modules, either within posterior parietal cortex or downstream within frontal cortex, may account for more complex behaviors such as hand-eye coordination and reach-to-grasp.
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Affiliation(s)
- Richard A Andersen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Kristen N Andersen
- Departments of Neurology and Pediatrics, University of California, Los Angeles Medical Center, Los Angeles, CA 90095, USA
| | - Eun Jung Hwang
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Markus Hauschild
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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63
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Disentangling neural representations of value and salience in the human brain. Proc Natl Acad Sci U S A 2014; 111:5000-5. [PMID: 24639493 DOI: 10.1073/pnas.1320189111] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A large body of evidence has implicated the posterior parietal and orbitofrontal cortex in the processing of value. However, value correlates perfectly with salience when appetitive stimuli are investigated in isolation. Accordingly, considerable uncertainty has remained about the precise nature of the previously identified signals. In particular, recent evidence suggests that neurons in the primate parietal cortex signal salience instead of value. To investigate neural signatures of value and salience, here we apply multivariate (pattern-based) analyses to human functional MRI data acquired during a noninstrumental outcome-prediction task involving appetitive and aversive outcomes. Reaction time data indicated additive and independent effects of value and salience. Critically, we show that multivoxel ensemble activity in the posterior parietal cortex encodes predicted value and salience in superior and inferior compartments, respectively. These findings reinforce the earlier reports of parietal value signals and reconcile them with the recent salience report. Moreover, we find that multivoxel patterns in the orbitofrontal cortex correlate with value. Importantly, the patterns coding for the predicted value of appetitive and aversive outcomes are similar, indicating a common neural scale for appetite and aversive values in the orbitofrontal cortex. Thus orbitofrontal activity patterns satisfy a basic requirement for a neural value signal.
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64
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Katsuki F, Constantinidis C. Bottom-up and top-down attention: different processes and overlapping neural systems. Neuroscientist 2013; 20:509-21. [PMID: 24362813 DOI: 10.1177/1073858413514136] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The brain is limited in its capacity to process all sensory stimuli present in the physical world at any point in time and relies instead on the cognitive process of attention to focus neural resources according to the contingencies of the moment. Attention can be categorized into two distinct functions: bottom-up attention, referring to attentional guidance purely by externally driven factors to stimuli that are salient because of their inherent properties relative to the background; and top-down attention, referring to internal guidance of attention based on prior knowledge, willful plans, and current goals. Over the past few years, insights on the neural circuits and mechanisms of bottom-up and top-down attention have been gained through neurophysiological experiments. Attention affects the mean neuronal firing rate as well as its variability and correlation across neurons. Although distinct processes mediate the guidance of attention based on bottom-up and top-down factors, a common neural apparatus, the frontoparietal network, is essential in both types of attentional processes.
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Affiliation(s)
- Fumi Katsuki
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Christos Constantinidis
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC, USA
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65
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Yttri EA, Wang C, Liu Y, Snyder LH. The parietal reach region is limb specific and not involved in eye-hand coordination. J Neurophysiol 2013; 111:520-32. [PMID: 24198328 DOI: 10.1152/jn.00058.2013] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Primates frequently reach toward visual targets. Neurons in early visual areas respond to stimuli in the contralateral visual hemifield and without regard to which limb will be used to reach toward that target. In contrast, neurons in motor areas typically respond when reaches are performed using the contralateral limb and with minimal regard to the visuospatial location of the target. The parietal reach region (PRR) is located early in the visuomotor processing hierarchy. PRR neurons are significantly modulated when targets for either limb or eye movement appear, similar to early sensory areas; however, they respond to targets in either visual field, similar to motor areas. The activity could reflect the subject's attentional locus, movement of a specific effector, or a related function, such as coordinating eye-arm movements. To examine the role of PRR in the visuomotor pathway, we reversibly inactivated PRR. Inactivation effects were specific to contralateral limb movements, leaving ipsilateral limb and saccadic movements intact. Neither visual hemifield bias nor visual attention deficits were observed. Thus our results are consistent with a motoric rather than visual organization in PRR, despite its early location in the visuomotor pathway. We found no effects on the temporal coupling of coordinated saccades and reaches, suggesting that this mechanism lies downstream of PRR. In sum, this study clarifies the role of PRR in the visuomotor hierarchy: despite its early position, it is a limb-specific area influencing reach planning and is positioned upstream from an active eye-hand coordination-coupling mechanism.
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Affiliation(s)
- Eric A Yttri
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri
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66
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Nishida S, Tanaka T, Ogawa T. Separate evaluation of target facilitation and distractor suppression in the activity of macaque lateral intraparietal neurons during visual search. J Neurophysiol 2013; 110:2773-91. [PMID: 24068752 DOI: 10.1152/jn.00360.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During visual search, neurons in the lateral intraparietal area (LIP) discriminate the target from distractors by exhibiting stronger activation when the target appears within the receptive field than when it appears outside the receptive field. It is generally thought that such target-discriminative activity is produced by the combination of target-related facilitation and distractor-related suppression. However, little is known about how the target-discriminative activity is constituted by these two types of neural modulation. To address this issue, we recorded activity from LIP of monkeys performing a visual search task that consisted of target-present and target-absent trials. Monkeys had to make a saccade to a target in the target-present trials, whereas they had to maintain fixation in the target-absent trials, in which only distractors were presented. By introducing the activity from the latter trials as neutral activity, we were able to separate the target-discriminative activity into target-related elevation and distractor-related reduction components. We found that the target-discriminative activity of most LIP neurons consisted of the combination of target-related elevation and distractor-related reduction or only target-related elevation. In contrast, target-discriminative activity composed of only distractor-related reduction was observed for very few neurons. We also found that, on average, target-related elevation was stronger and occurred earlier compared with distractor-related reduction. Finally, we consider possible underlying mechanisms, including lateral inhibitory interactions, responsible for target-discriminative activity in visual search. The present findings provide insight into how neuronal modulations shape target-discriminative activity during visual search.
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Affiliation(s)
- Satoshi Nishida
- Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan
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67
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Wilke M, Kagan I, Andersen RA. Effects of Pulvinar Inactivation on Spatial Decision-making between Equal and Asymmetric Reward Options. J Cogn Neurosci 2013; 25:1270-83. [DOI: 10.1162/jocn_a_00399] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Abstract
The ability to selectively process visual inputs and to decide between multiple movement options in an adaptive manner is critical for survival. Such decisions are known to be influenced by factors such as reward expectation and visual saliency. The dorsal pulvinar connects to a multitude of cortical areas that are involved in visuospatial memory and integrate information about upcoming eye movements with expected reward values. However, it is unclear whether the dorsal pulvinar is critically involved in spatial memory and reward-based oculomotor decision behavior. To examine this, we reversibly inactivated the dorsal portion of the pulvinar while monkeys performed a delayed memory saccade task that included choices between equally or unequally rewarded options. Pulvinar inactivation resulted in a delay of saccade initiation toward memorized contralesional targets but did not affect spatial memory. Furthermore, pulvinar inactivation caused a pronounced choice bias toward the ipsilesional hemifield when the reward value in the two hemifields was equal. However, this choice bias could be alleviated by placing a high reward target into the contralesional hemifield. The bias was less affected by the manipulation of relative visual saliency between the two competing targets. These results suggest that the dorsal pulvinar is involved in determining the behavioral desirability of movement goals while being less critical for spatial memory and reward processing.
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Affiliation(s)
- Melanie Wilke
- 1California Institute of Technology
- 2University of Goettingen
- 3German Primate Center, Leibniz Institute for Primate Research, Goettingen, Germany
| | - Igor Kagan
- 1California Institute of Technology
- 3German Primate Center, Leibniz Institute for Primate Research, Goettingen, Germany
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68
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Gallivan JP, Chapman CS, McLean DA, Flanagan JR, Culham JC. Activity patterns in the category-selective occipitotemporal cortex predict upcoming motor actions. Eur J Neurosci 2013; 38:2408-24. [PMID: 23581683 DOI: 10.1111/ejn.12215] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 03/10/2013] [Indexed: 12/01/2022]
Abstract
Converging lines of evidence point to the occipitotemporal cortex (OTC) as a critical structure in visual perception. For instance, human functional magnetic resonance imaging (fMRI) has revealed a modular organisation of object-selective, face-selective, body-selective and scene-selective visual areas in the OTC, and disruptions to the processing within these regions, either in neuropsychological patients or through transcranial magnetic stimulation, can produce category-specific deficits in visual recognition. Here we show, using fMRI and pattern classification methods, that the activity in the OTC also represents how stimuli will be interacted with by the body--a level of processing more traditionally associated with the preparatory activity in sensorimotor circuits of the brain. Combining functional mapping of different OTC areas with a real object-directed delayed movement task, we found that the pre-movement spatial activity patterns across the OTC could be used to predict both the action of an upcoming hand movement (grasping vs. reaching) and the effector (left hand vs. right hand) to be used. Interestingly, we were able to extract this wide range of predictive movement information even though nearly all OTC areas showed either baseline-level or below baseline-level activity prior to action onset. Our characterisation of different OTC areas according to the features of upcoming movements that they could predict also revealed a general gradient of effector-to-action-dependent movement representations along the posterior-anterior OTC axis. These findings suggest that the ventral visual pathway, which is well known to be involved in object recognition and perceptual processing, plays a larger than previously expected role in preparing object-directed hand actions.
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Affiliation(s)
- Jason P Gallivan
- Centre for Neuroscience Studies, Department of Psychology, Queen's University, Kingston, ON, Canada.
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69
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Hwang EJ, Hauschild M, Wilke M, Andersen RA. Inactivation of the parietal reach region causes optic ataxia, impairing reaches but not saccades. Neuron 2013; 76:1021-9. [PMID: 23217749 DOI: 10.1016/j.neuron.2012.10.030] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2012] [Indexed: 11/17/2022]
Abstract
Lesions in human posterior parietal cortex can cause optic ataxia (OA), in which reaches but not saccades to visual objects are impaired, suggesting separate visuomotor pathways for the two effectors. In monkeys, one potentially crucial area for reach control is the parietal reach region (PRR), in which neurons respond preferentially during reach planning as compared to saccade planning. However, direct causal evidence linking the monkey PRR to the deficits observed in OA is missing. We thus inactivated part of the macaque PRR, in the medial wall of the intraparietal sulcus, and produced the hallmarks of OA, misreaching for peripheral targets but unimpaired saccades. Furthermore, reach errors were larger for the targets preferred by the neural population local to the injection site. These results demonstrate that PRR is causally involved in reach-specific visuomotor pathways, and reach goal disruption in PRR can be a neural basis of OA.
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Affiliation(s)
- Eun Jung Hwang
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
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70
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Gillebert CR, Mantini D, Peeters R, Dupont P, Vandenberghe R. Cytoarchitectonic mapping of attentional selection and reorienting in parietal cortex. Neuroimage 2013. [DOI: 10.1016/j.neuroimage.2012.11.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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71
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Lesions of cortical area LIP affect reach onset only when the reach is accompanied by a saccade, revealing an active eye-hand coordination circuit. Proc Natl Acad Sci U S A 2013; 110:2371-6. [PMID: 23341626 DOI: 10.1073/pnas.1220508110] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The circuits that drive visually guided eye and arm movements transform generic visual inputs into effector-specific motor commands. As part of the effort to elucidate these circuits, the primate lateral intraparietal area (LIP) has been interpreted as a priority map for saccades (oculomotor-specific) or a salience map of space (not effector-specific). It has also been proposed as a locus for eye-hand coordination. We reversibly inactivated LIP while monkeys performed memory-guided saccades and reaches. Coordinated saccade and reach reaction times were similarly impaired, consistent with a nonspecific role. However, reaches made without an accompanying saccade remained intact, and the relative temporal coupling of saccades and reaches was unchanged. These results suggest that LIP contributes to saccade planning but not to reach planning. Coordinated reaches are delayed as a result of an eye-hand coordination mechanism, located outside of LIP, that actively delays reaches until shortly after the onset of an associated saccade. We conclude with a discussion of how to reconcile specificity for saccades with a possible role in directing attention.
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72
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Noudoost B, Moore T. Parietal and prefrontal neurons driven to distraction. Nat Neurosci 2012; 16:8-9. [PMID: 23257928 DOI: 10.1038/nn.3291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Behrad Noudoost
- Department of Neurobiology and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, USA
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73
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Jonikaitis D, Szinte M, Rolfs M, Cavanagh P. Allocation of attention across saccades. J Neurophysiol 2012; 109:1425-34. [PMID: 23221410 DOI: 10.1152/jn.00656.2012] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Whenever the eyes move, spatial attention must keep track of the locations of targets as they shift on the retina. This study investigated transsaccadic updating of visual attention to cued targets. While observers prepared a saccade, we flashed an irrelevant, but salient, color cue in their visual periphery and measured the allocation of spatial attention before and after the saccade using a tilt discrimination task. We found that just before the saccade, attention was allocated to the cue's future retinal location, its predictively "remapped" location. Attention was sustained at the cue's location in the world across the saccade, despite the change of retinal position whereas it decayed quickly at the retinal location of the cue, after the eye landed. By extinguishing the color cue across the saccade, we further demonstrate that the visual system relies only on predictive allocation of spatial attention, as the presence of the cue after the saccade did not substantially affect attentional allocation. These behavioral results support and extend physiological evidence showing predictive activation of visual neurons when an attended stimulus will fall in their receptive field after a saccade. Our results show that tracking of spatial locations across saccades is a plausible consequence of physiological remapping.
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Affiliation(s)
- Donatas Jonikaitis
- 1Allgemeine und Experimentelle Psychologie, Ludwig-Maximilians Universität München, Munich, Germany.
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74
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Huk AC, Meister MLR. Neural correlates and neural computations in posterior parietal cortex during perceptual decision-making. Front Integr Neurosci 2012; 6:86. [PMID: 23087623 PMCID: PMC3467999 DOI: 10.3389/fnint.2012.00086] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 09/11/2012] [Indexed: 11/13/2022] Open
Abstract
A recent line of work has found remarkable success in relating perceptual decision-making and the spiking activity in the macaque lateral intraparietal area (LIP). In this review, we focus on questions about the neural computations in LIP that are not answered by demonstrations of neural correlates of psychological processes. We highlight three areas of limitations in our current understanding of the precise neural computations that might underlie neural correlates of decisions: (1) empirical questions not yet answered by existing data; (2) implementation issues related to how neural circuits could actually implement the mechanisms suggested by both extracellular neurophysiology and psychophysics; and (3) ecological constraints related to the use of well-controlled laboratory tasks and whether they provide an accurate window on sensorimotor computation. These issues motivate the adoption of a more general "encoding-decoding framework" that will be fruitful for more detailed contemplation of how neural computations in LIP relate to the formation of perceptual decisions.
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Affiliation(s)
- Alexander C. Huk
- Center for Perceptual Systems, Institute for Neuroscience, Neurobiology, and Psychology, The University of Texas at AustinAustin, TX, USA
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75
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Premereur E, Vanduffel W, Roelfsema PR, Janssen P. Frontal eye field microstimulation induces task-dependent gamma oscillations in the lateral intraparietal area. J Neurophysiol 2012; 108:1392-402. [PMID: 22673327 DOI: 10.1152/jn.00323.2012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Macaque frontal eye fields (FEF) and the lateral intraparietal area (LIP) are high-level oculomotor control centers that have been implicated in the allocation of spatial attention. Electrical microstimulation of macaque FEF elicits functional magnetic resonance imaging (fMRI) activations in area LIP, but no study has yet investigated the effect of FEF microstimulation on LIP at the single-cell or local field potential (LFP) level. We recorded spiking and LFP activity in area LIP during weak, subthreshold microstimulation of the FEF in a delayed-saccade task. FEF microstimulation caused a highly time- and frequency-specific, task-dependent increase in gamma power in retinotopically corresponding sites in LIP: FEF microstimulation produced a significant increase in LIP gamma power when a saccade target appeared and remained present in the LIP receptive field (RF), whereas less specific increases in alpha power were evoked by FEF microstimulation for saccades directed away from the RF. Stimulating FEF with weak currents had no effect on LIP spike rates or on the gamma power during memory saccades or passive fixation. These results provide the first evidence for task-dependent modulations of LFPs in LIP caused by top-down stimulation of FEF. Since the allocation and disengagement of spatial attention in visual cortex have been associated with increases in gamma and alpha power, respectively, the effects of FEF microstimulation on LIP are consistent with the known effects of spatial attention.
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Affiliation(s)
- Elsie Premereur
- Katholieke Universiteit Leuven, O&N 2, Laboratorium voor Neuro- en Psychofysiologie, Herestraat 49, Bus 1021, 3000 Leuven, Belgium.
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76
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Functional imaging reveals rapid reorganization of cortical activity after parietal inactivation in monkeys. Proc Natl Acad Sci U S A 2012; 109:8274-9. [PMID: 22562793 DOI: 10.1073/pnas.1204789109] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Impairments of spatial awareness and decision making occur frequently as a consequence of parietal lesions. Here we used event-related functional MRI (fMRI) in monkeys to investigate rapid reorganization of spatial networks during reversible pharmacological inactivation of the lateral intraparietal area (LIP), which plays a role in the selection of eye movement targets. We measured fMRI activity in control and inactivation sessions while monkeys performed memory saccades to either instructed or autonomously chosen spatial locations. Inactivation caused a reduction of contralesional choices. Inactivation effects on fMRI activity were anatomically and functionally specific and mainly consisted of: (i) activity reduction in the upper bank of the superior temporal sulcus (temporal parietal occipital area) for single contralesional targets, especially in the inactivated hemisphere; and (ii) activity increase accompanying contralesional choices between bilateral targets in several frontal and parieto-temporal areas in both hemispheres. There was no overactivation for ipsilesional targets or choices in the intact hemisphere. Task-specific effects of LIP inactivation on blood oxygen level-dependent activity in the temporal parietal occipital area underline the importance of the superior temporal sulcus for spatial processing. Furthermore, our results agree only partially with the influential interhemispheric competition model of spatial neglect and suggest an additional component of interhemispheric cooperation in the compensation of neglect deficits.
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77
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Katsuki F, Constantinidis C. Unique and shared roles of the posterior parietal and dorsolateral prefrontal cortex in cognitive functions. Front Integr Neurosci 2012; 6:17. [PMID: 22563310 PMCID: PMC3342558 DOI: 10.3389/fnint.2012.00017] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 04/16/2012] [Indexed: 11/24/2022] Open
Abstract
The dorsolateral prefrontal cortex (PFC) and posterior parietal cortex (PPC) are two parts of a broader brain network involved in the control of cognitive functions such as working-memory, spatial attention, and decision-making. The two areas share many functional properties and exhibit similar patterns of activation during the execution of mental operations. However, neurophysiological experiments in non-human primates have also documented subtle differences, revealing functional specialization within the fronto-parietal network. These differences include the ability of the PFC to influence memory performance, attention allocation, and motor responses to a greater extent, and to resist interference by distracting stimuli. In recent years, distinct cellular and anatomical differences have been identified, offering insights into how functional specialization is achieved. This article reviews the common functions and functional differences between the PFC and PPC, and their underlying mechanisms.
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Affiliation(s)
- Fumi Katsuki
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem NC, USA
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78
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Causal links between dorsal medial superior temporal area neurons and multisensory heading perception. J Neurosci 2012; 32:2299-313. [PMID: 22396405 DOI: 10.1523/jneurosci.5154-11.2012] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The dorsal medial superior temporal area (MSTd) in the extrastriate visual cortex is thought to play an important role in heading perception because neurons in this area are tuned to both optic flow and vestibular signals. MSTd neurons also show significant correlations with perceptual judgments during a fine heading direction discrimination task. To test for a causal link with heading perception, we used microstimulation and reversible inactivation techniques to artificially perturb MSTd activity while monitoring behavioral performance. Electrical microstimulation significantly biased monkeys' heading percepts based on optic flow, but did not significantly impact vestibular heading judgments. The latter result may be due to the fact that vestibular heading preferences in MSTd are more weakly clustered than visual preferences and multiunit tuning for vestibular stimuli is weak. Reversible chemical inactivation, however, increased behavioral thresholds when heading judgments were based on either optic flow or vestibular cues, although the magnitude of the effects was substantially stronger for optic flow. Behavioral deficits in a combined visual/vestibular stimulus condition were intermediate between the single-cue effects. Despite deficits in discrimination thresholds, animals were able to combine visual and vestibular cues near optimally, even after large bilateral muscimol injections into MSTd. Simulations show that the overall pattern of results following inactivation is consistent with a mixture of contributions from MSTd and other areas with vestibular-dominant tuning for heading. Our results support a causal link between MSTd neurons and multisensory heading perception but suggest that other multisensory brain areas also contribute.
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Gerits A, Ruff CC, Guipponi O, Wenderoth N, Driver J, Vanduffel W. Response to comment on: Exp Brain Res. 2011 May 5th. Transcranial magnetic stimulation of macaque frontal eye fields decreases saccadic reaction time. Pierre Pouget PhD, Nicolas Wattiez MSc and Antoni Valero-Cabre MDPhD. Exp Brain Res 2012; 218:157-8. [DOI: 10.1007/s00221-012-3022-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 08/08/2011] [Indexed: 11/24/2022]
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80
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Reorganization of Oscillatory Activity in Human Parietal Cortex during Spatial Updating. Cereb Cortex 2012; 23:508-19. [DOI: 10.1093/cercor/bhr387] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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81
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Chang SWC, Snyder LH. The representations of reach endpoints in posterior parietal cortex depend on which hand does the reaching. J Neurophysiol 2012; 107:2352-65. [PMID: 22298831 DOI: 10.1152/jn.00852.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neurons in the parietal reach region (PRR) have been implicated in the sensory-to-motor transformation required for reaching toward visually defined targets. The neurons in each cortical hemisphere might be specifically involved in planning movements of just one limb, or the PRR might code reach endpoints generically, independent of which limb will actually move. Previous work has shown that the preferred directions of PRR neurons are similar for right and left limb movements but that the amplitude of modulation may vary greatly. We now test the hypothesis that frames of reference and eye and hand gain field modulations will, like preferred directions, be independent of which hand moves. This was not the case. Many neurons show clear differences in both the frame of reference as well as in direction and strength of gain field modulations, depending on which hand is used to reach. The results suggest that the information that is conveyed from the PRR to areas closer to the motor output (the readout from the PRR) is different for each limb and that individual PRR neurons contribute either to controlling the contralateral-limb or else bimanual-limb control.
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Affiliation(s)
- Steve W C Chang
- Center for Cognitive Neuroscience, Department of Neurobiology, Duke University Medical Center, Durham, NC 27701, USA.
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82
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Abstract
The macaque lateral intraparietal area (LIP) has been implicated in many cognitive processes, ranging from saccade planning and spatial attention to timing and categorization. Importantly, different research groups have used different criteria for including LIP neurons in their studies. While some research groups have selected LIP neurons based on the presence of memory-delay activity, other research groups have used other criteria such as visual, presaccadic, and/or memory activity. We recorded from LIP neurons that were selected based on spatially selective saccadic activity but regardless of memory-delay activity in macaque monkeys. To test anticipatory climbing activity, we used a delayed visually guided saccade task with a unimodal schedule of go-times, for which the conditional probability that the go-signal will occur rises monotonically as a function of time. A subpopulation of LIP neurons showed anticipatory activity that mimicked the subjective hazard rate of the go-signal when the animal was planning a saccade toward the receptive field. A large subgroup of LIP neurons, however, did not modulate their firing rates according to the subjective hazard function. These non-anticipatory neurons were strongly influenced by salient visual stimuli appearing in their receptive field, but less so by the direction of the impending saccade. Thus, LIP contains a heterogeneous population of neurons related to saccade planning or visual salience, and these neurons are spatially intermixed. Our results suggest that between-study differences in neuronal selection may have contributed significantly to the findings of different research groups with respect to the functional role of area LIP.
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83
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Alkan Y, Biswal BB, Alvarez TL. Differentiation between vergence and saccadic functional activity within the human frontal eye fields and midbrain revealed through fMRI. PLoS One 2011; 6:e25866. [PMID: 22073141 PMCID: PMC3206796 DOI: 10.1371/journal.pone.0025866] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 09/12/2011] [Indexed: 12/28/2022] Open
Abstract
PURPOSE Eye movement research has traditionally studied solely saccade and/or vergence eye movements by isolating these systems within a laboratory setting. While the neural correlates of saccadic eye movements are established, few studies have quantified the functional activity of vergence eye movements using fMRI. This study mapped the neural substrates of vergence eye movements and compared them to saccades to elucidate the spatial commonality and differentiation between these systems. METHODOLOGY The stimulus was presented in a block design where the 'off' stimulus was a sustained fixation and the 'on' stimulus was random vergence or saccadic eye movements. Data were collected with a 3T scanner. A general linear model (GLM) was used in conjunction with cluster size to determine significantly active regions. A paired t-test of the GLM beta weight coefficients was computed between the saccade and vergence functional activities to test the hypothesis that vergence and saccadic stimulation would have spatial differentiation in addition to shared neural substrates. RESULTS Segregated functional activation was observed within the frontal eye fields where a portion of the functional activity from the vergence task was located anterior to the saccadic functional activity (z>2.3; p<0.03). An area within the midbrain was significantly correlated with the experimental design for the vergence but not the saccade data set. Similar functional activation was observed within the following regions of interest: the supplementary eye field, dorsolateral prefrontal cortex, ventral lateral prefrontal cortex, lateral intraparietal area, cuneus, precuneus, anterior and posterior cingulates, and cerebellar vermis. The functional activity from these regions was not different between the vergence and saccade data sets assessed by analyzing the beta weights of the paired t-test (p>0.2). CONCLUSION Functional MRI can elucidate the differences between the vergence and saccade neural substrates within the frontal eye fields and midbrain.
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Affiliation(s)
- Yelda Alkan
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, New Jersey, United States of America
| | - Bharat B. Biswal
- Department of Radiology, University of Medicine and Dentistry of New Jersey, Newark, New Jersey, United States of America
| | - Tara L. Alvarez
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, New Jersey, United States of America
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84
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Medendorp WP, Buchholz VN, Van Der Werf J, Leoné FTM. Parietofrontal circuits in goal-oriented behaviour. Eur J Neurosci 2011; 33:2017-27. [PMID: 21645097 DOI: 10.1111/j.1460-9568.2011.07701.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Parietal and frontal cortical areas play important roles in the control of goal-oriented behaviour. This review examines how signal processing in the parietal and frontal eye fields is involved in coding and storing space, directing attention and processing the sensorimotor transformation for saccades. After a survey of the functional specialization of these areas in monkeys, we discuss homologous regions in the human brain in terms of topographic organization, storage capacity, target selection, spatial remapping, reference frame transformations and effector specificity. The overall picture suggests that bottom-up sensory, top-down cognitive signals and efferent motor signals are integrated in dynamic sensorimotor maps as part of a functionally flexible parietofrontal network. Neuronal synchronization in these maps may be instrumental in amplifying behaviourally relevant representations and setting up a functional pathway to route information in this parietofrontal circuit.
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Affiliation(s)
- W Pieter Medendorp
- Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, NL 6500 HE, Nijmegen, The Netherlands.
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85
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Wardak C, Olivier E, Duhamel JR. The relationship between spatial attention and saccades in the frontoparietal network of the monkey. Eur J Neurosci 2011; 33:1973-81. [PMID: 21645093 DOI: 10.1111/j.1460-9568.2011.07710.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Claire Wardak
- Centre de Neuroscience Cognitive, UMR5229 CNRS - Université Claude Bernard Lyon 1, Bron Cedex, France.
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86
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Baluch F, Itti L. Mechanisms of top-down attention. Trends Neurosci 2011; 34:210-24. [DOI: 10.1016/j.tins.2011.02.003] [Citation(s) in RCA: 188] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 02/08/2011] [Accepted: 02/08/2011] [Indexed: 12/14/2022]
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Galletti C, Breveglieri R, Lappe M, Bosco A, Ciavarro M, Fattori P. Covert shift of attention modulates the ongoing neural activity in a reaching area of the macaque dorsomedial visual stream. PLoS One 2010; 5:e15078. [PMID: 21124734 PMCID: PMC2993960 DOI: 10.1371/journal.pone.0015078] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Accepted: 10/26/2010] [Indexed: 11/19/2022] Open
Abstract
Background Attention is used to enhance neural processing of selected parts of a visual scene. It increases neural responses to stimuli near target locations and is usually coupled to eye movements. Covert attention shifts, however, decouple the attentional focus from gaze, allowing to direct the attention to a peripheral location without moving the eyes. We tested whether covert attention shifts modulate ongoing neuronal activity in cortical area V6A, an area that provides a bridge between visual signals and arm-motor control. Methodology/Principal Findings We performed single cell recordings from 3 Macaca Fascicularis trained to fixate straight-head, while shifting attention outward to a peripheral cue and inward again to the fixation point. We found that neurons in V6A are influenced by spatial attention. The attentional modulation occurs without gaze shifts and cannot be explained by visual stimulations. Visual, motor, and attentional responses can occur in combination in single neurons. Conclusions/Significance This modulation in an area primarily involved in visuo-motor transformation for reaching may form a neural basis for coupling attention to the preparation of reaching movements. Our results show that cortical processes of attention are related not only to eye-movements, as many studies have shown, but also to arm movements, a finding that has been suggested by some previous behavioral findings. Therefore, the widely-held view that spatial attention is tightly intertwined with—and perhaps directly derived from—motor preparatory processes should be extended to a broader spectrum of motor processes than just eye movements.
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Affiliation(s)
- Claudio Galletti
- Dipartimento di Fisiologia Umana e Generale, Universita' di Bologna, Bologna, Italy
| | - Rossella Breveglieri
- Dipartimento di Fisiologia Umana e Generale, Universita' di Bologna, Bologna, Italy
| | - Markus Lappe
- Department of Psychology and Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, Westfälische Wilhelms-University, Münster, Germany
| | - Annalisa Bosco
- Dipartimento di Fisiologia Umana e Generale, Universita' di Bologna, Bologna, Italy
| | - Marco Ciavarro
- Dipartimento di Fisiologia Umana e Generale, Universita' di Bologna, Bologna, Italy
| | - Patrizia Fattori
- Dipartimento di Fisiologia Umana e Generale, Universita' di Bologna, Bologna, Italy
- * E-mail:
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88
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Lin IF, Gorea A. Location and identity memory of saccade targets. Vision Res 2010; 51:323-32. [PMID: 21115027 DOI: 10.1016/j.visres.2010.11.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 10/17/2010] [Accepted: 11/22/2010] [Indexed: 11/16/2022]
Abstract
While the memory of objects' identity and of their spatiotopic location may sustain transsaccadic spatial constancy, the memory of their retinotopic location may hamper it. Is it then true that saccades perturb retinotopic but not spatiotopic memory? We address this issue by assessing localization performances of the last and of the penultimate saccade target in a series of 2-6 saccades. Upon fixation, nine letter-pairs, eight black and one white, were displayed at 3° eccentricity around fixation within a 20° × 20° grey frame, and subjects were instructed to saccade to the white letter-pair; the cycle was then repeated. Identical conditions were run with the eyes maintaining fixation throughout the trial but with the grey frame moving so as to mimic its retinal displacement when the eyes moved. At the end of a trial, subjects reported the identity and/or the location of the target in either retinotopic (relative to the current fixation dot) or frame-based(1) (relative to the grey frame) coordinates. Saccades degraded target's retinotopic location memory but not its frame-based location or its identity memory. Results are compatible with the notion that spatiotopic representation takes over retinotopic representation during eye movements thereby contributing to the stability of the visual world as its retinal projection jumps on our retina from saccade to saccade.
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Affiliation(s)
- I-Fan Lin
- Laboratorie Psychologie de la Perception, Paris Descartes University and CNRS, 45 rue des Saints Pères, 75006 Paris, France
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Spatial and non-spatial functions of the parietal cortex. Curr Opin Neurobiol 2010; 20:731-40. [PMID: 21050743 DOI: 10.1016/j.conb.2010.09.015] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 09/28/2010] [Accepted: 09/29/2010] [Indexed: 11/21/2022]
Abstract
Although the parietal cortex is traditionally associated with spatial attention and sensorimotor integration, recent evidence also implicates it in higher order cognitive functions. We review relevant results from neuron recording studies showing that inferior parietal neurons integrate information regarding target location with a variety of non-spatial signals. Some of these signals are modulatory and alter a stimulus-evoked response according to the action, category, or reward associated with the stimulus. Other non-spatial inputs act independently, encoding the context or rules of a task even before the presentation of a specific target. Despite the ubiquity of non-spatial information in individual neurons, reversible inactivation of the parietal lobe affects only spatial orienting of attention and gaze, but not non-spatial aspects of performance. This suggests that non-spatial signals contribute to an underlying spatial computation, possibly allowing the brain to determine which targets are worthy of attention or action in a given task context.
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90
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Cotti J, Rohenkohl G, Stokes M, Nobre AC, Coull JT. Functionally dissociating temporal and motor components of response preparation in left intraparietal sulcus. Neuroimage 2010; 54:1221-30. [PMID: 20868756 PMCID: PMC3025354 DOI: 10.1016/j.neuroimage.2010.09.038] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 09/09/2010] [Accepted: 09/16/2010] [Indexed: 11/29/2022] Open
Abstract
To optimise speed and accuracy of motor behaviour, we can prepare not only the type of movement to be made but also the time at which it will be executed. Previous cued reaction-time paradigms have shown that anticipating the moment in time at which this response will be made (“temporal orienting”) or selectively preparing the motor effector with which an imminent response will be made (motor intention or “motor orienting”) recruits similar regions of left intraparietal sulcus (IPS), raising the possibility that these two preparatory processes are inextricably co-activated. We used a factorial design to independently cue motor and temporal components of response preparation within the same experimental paradigm. By differentially cueing either ocular or manual response systems, rather than spatially lateralised responses within just one of these systems, potential spatial confounds were removed. We demonstrated that temporal and motor orienting were behaviourally dissociable, each capable of improving performance alone. Crucially, fMRI data revealed that temporal orienting activated the left IPS even if the motor effector that would be used to execute the response was unpredictable. Moreover, temporal orienting activated left IPS whether the target required a saccadic or manual response, and whether this response was left- or right-sided, thus confirming the ubiquity of left IPS activation for temporal orienting. Finally, a small region of left IPS was also activated by motor orienting for manual, though not saccadic, responses. Despite their functional independence therefore, temporal orienting and manual motor orienting nevertheless engage partially overlapping regions of left IPS, possibly reflecting their shared ontogenetic roots.
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Affiliation(s)
- Julien Cotti
- Laboratoire de Neurobiologie de la Cognition, Université de Provence & CNRS, Marseille, France
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91
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Heider B, Karnik A, Ramalingam N, Siegel RM. Neural representation during visually guided reaching in macaque posterior parietal cortex. J Neurophysiol 2010; 104:3494-509. [PMID: 20844104 DOI: 10.1152/jn.01050.2009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Visually guided hand movements in primates require an interconnected network of various cortical areas. Single unit firing rate from area 7a and dorsal prelunate (DP) neurons of macaque posterior parietal cortex (PPC) was recorded during reaching movements to targets at variable locations and under different eye position conditions. In the eye position-varied task, the reach target was always foveated; thus eye position varied with reach target location. In the retinal-varied task, the monkey reached to targets at variable retinotopic locations while eye position was kept constant in the center. Spatial tuning was examined with respect to temporal (task epoch) and contextual (task condition) aspects, and response fields were compared. The analysis showed distinct tuning types. The majority of neurons changed their gain field tuning and retinotopic tuning between different phases of the task. Between the onset of visual stimulation and the preparatory phase (before the go signal), about one half the neurons altered their firing rate significantly. Spatial response fields during preparation and initiation epochs were strongly influenced by the task condition (eye position varied vs. retinal varied), supporting a strong role of eye position during visually guided reaching. DP neurons, classically considered visual, showed reach related modulation similar to 7a neurons. This study shows that both area 7a and DP are modulated during reaching behavior in primates. The various tuning types in both areas suggest distinct populations recruiting different circuits during visually guided reaching.
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Affiliation(s)
- Barbara Heider
- Ctr. for Molecular and Behavioral Neuroscience, Rutgers Univ., 197 University Ave., Newark, NJ 07102, USA.
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92
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Abstract
Visual attention is the mechanism the nervous system uses to highlight specific locations, objects or features within the visual field. This can be accomplished by making an eye movement to bring the object onto the fovea (overt attention) or by increased processing of visual information in neurons representing more peripheral regions of the visual field (covert attention). This review will examine two aspects of visual attention: the changes in neural responses within visual cortices due to the allocation of covert attention; and the neural activity in higher cortical areas involved in guiding the allocation of attention. The first section will highlight processes that occur during visual spatial attention and feature-based attention in cortical visual areas and several related models that have recently been proposed to explain this activity. The second section will focus on the parietofrontal network thought to be involved in targeting eye movements and allocating covert attention. It will describe evidence that the lateral intraparietal area, frontal eye field and superior colliculus are involved in the guidance of visual attention, and describe the priority map model, which is thought to operate in at least several of these areas.
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Affiliation(s)
- James W Bisley
- Department of Neurobiology and Jules Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1763, USA.
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93
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Abstract
The coordinated movement of the eyes and hands under visual guidance is an essential part of goal-directed behavior. Several cortical areas known to be involved in this process exchange projections with the dorsal aspect of the thalamic pulvinar nucleus, suggesting that this structure may play a central role in visuomotor behavior. Here, we used reversible inactivation to investigate the role of the dorsal pulvinar in the selection and execution of visually guided manual and saccadic eye movements in macaque monkeys. We found that unilateral pulvinar inactivation resulted in a spatial neglect syndrome accompanied by visuomotor deficits including optic ataxia during visually guided limb movements. Monkeys were severely disrupted in their visually guided behavior regarding space contralateral to the side of the injection in several domains, including the following: (1) target selection in both manual and oculomotor tasks, (2) limb usage in a manual retrieval task, and (3) spontaneous visual exploration. In addition, saccades into the ipsilesional field had abnormally short latencies and tended to overshoot their mark. None of the deficits could be explained by a visual field defect or primary motor deficit. These findings highlight the importance of the dorsal aspect of the pulvinar nucleus as a critical hub for spatial attention and selection of visually guided actions.
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94
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Abstract
Despite several attempts to define retinotopic maps in the macaque lateral intraparietal area (LIP) using histological, electrophysiological, and neuroimaging methods, the degree to which this area is topographically organized remains controversial. We recorded blood oxygenation level-dependent signals with functional MRI from two macaques performing a difficult visual search task on stimuli presented at the fovea or in the periphery of the visual field. The results revealed the presence of a single topographic representation of the contralateral hemifield in the ventral subdivision of the LIP (LIPv) in both hemispheres of both monkeys. Also, a foveal representation was localized in rostral LIPv rather than in dorsal LIP (LIPd) as previous experiments had suggested. Finally, both LIPd and LIPv responded only to contralateral stimuli. In contrast, human studies have reported multiple topographic maps in intraparietal cortex and robust responses to ipsilateral stimuli. These blood oxygenation level-dependent functional MRI results provide clear evidence for the topographic organization of macaque LIP that complements the results of previous electrophysiology studies, and also reveal some unexpected characteristics of this organization that have eluded these previous studies. The results also delineate organizational differences between LIPv and LIPd, providing support for these two histologically defined areas may subserve different visuospatial functions. Finally, these findings point to potential evolutionary differences in functional organization with human posterior parietal cortex.
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