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Busch A, Roussy M, Luna R, Leavitt ML, Mofrad MH, Gulli RA, Corrigan B, Mináč J, Sachs AJ, Palaniyappan L, Muller L, Martinez-Trujillo JC. Neuronal activation sequences in lateral prefrontal cortex encode visuospatial working memory during virtual navigation. Nat Commun 2024; 15:4471. [PMID: 38796480 PMCID: PMC11127969 DOI: 10.1038/s41467-024-48664-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Accepted: 05/01/2024] [Indexed: 05/28/2024] Open
Abstract
Working memory (WM) is the ability to maintain and manipulate information 'in mind'. The neural codes underlying WM have been a matter of debate. We simultaneously recorded the activity of hundreds of neurons in the lateral prefrontal cortex of male macaque monkeys during a visuospatial WM task that required navigation in a virtual 3D environment. Here, we demonstrate distinct neuronal activation sequences (NASs) that encode remembered target locations in the virtual environment. This NAS code outperformed the persistent firing code for remembered locations during the virtual reality task, but not during a classical WM task using stationary stimuli and constraining eye movements. Finally, blocking NMDA receptors using low doses of ketamine deteriorated the NAS code and behavioral performance selectively during the WM task. These results reveal the versatility and adaptability of neural codes supporting working memory function in the primate lateral prefrontal cortex.
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Affiliation(s)
- Alexandra Busch
- Robarts Research Institute, University of Western Ontario, London, ON, Canada
- Brain and Mind Institute, University of Western Ontario, London, ON, Canada
- Department of Mathematics, University of Western Ontario, London, ON, Canada
| | - Megan Roussy
- Robarts Research Institute, University of Western Ontario, London, ON, Canada
- Brain and Mind Institute, University of Western Ontario, London, ON, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada
| | - Rogelio Luna
- Robarts Research Institute, University of Western Ontario, London, ON, Canada
- Brain and Mind Institute, University of Western Ontario, London, ON, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada
| | | | - Maryam H Mofrad
- Brain and Mind Institute, University of Western Ontario, London, ON, Canada
- Department of Mathematics, University of Western Ontario, London, ON, Canada
| | - Roberto A Gulli
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Benjamin Corrigan
- Robarts Research Institute, University of Western Ontario, London, ON, Canada
- Brain and Mind Institute, University of Western Ontario, London, ON, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada
| | - Ján Mináč
- Department of Mathematics, University of Western Ontario, London, ON, Canada
| | - Adam J Sachs
- The Ottawa Hospital, University of Ottawa, Ottawa, ON, Canada
| | - Lena Palaniyappan
- Robarts Research Institute, University of Western Ontario, London, ON, Canada
- Department of Psychiatry, University of Western Ontario, London, ON, Canada
- Lawson Health Research Institute, London, ON, Canada
| | - Lyle Muller
- Robarts Research Institute, University of Western Ontario, London, ON, Canada.
- Brain and Mind Institute, University of Western Ontario, London, ON, Canada.
- Department of Mathematics, University of Western Ontario, London, ON, Canada.
| | - Julio C Martinez-Trujillo
- Robarts Research Institute, University of Western Ontario, London, ON, Canada.
- Brain and Mind Institute, University of Western Ontario, London, ON, Canada.
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada.
- Lawson Health Research Institute, London, ON, Canada.
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2
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Sun Y, Dang W, Jaffe RG, Constantinidis C. Local organization of spatial and shape information during working memory in the primate prefrontal cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.26.554962. [PMID: 37693624 PMCID: PMC10491106 DOI: 10.1101/2023.08.26.554962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
While the current understanding of sensory and motor cortical areas has been defined topographical maps across the surface of these areas, higher cortical areas, such as the prefrontal cortex, seem to lack an equivalent organization, with only limited evidence of functional clustering of neurons with similar stimulus properties. We sought to examine whether neurons that represent similar spatial and object information are clustered in the monkey prefrontal cortex and whether such an organization only emerges as a result of training. We analyzed neurophysiological recordings from male macaque monkeys before and after they were trained to perform cognitive tasks. Neurons with similar spatial or shape selectivity were more likely than chance to be encountered at short distances from each other. This pattern of organization was present even in naïve animals, prior to any cognitive training. Our results reveal that prefrontal microstructure automatically supports orderly representations of spatial and object information.
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3
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Rouzitalab A, Boulay CB, Park J, Sachs AJ. Intracortical brain-computer interfaces in primates: a review and outlook. Biomed Eng Lett 2023; 13:375-390. [PMID: 37519868 PMCID: PMC10382423 DOI: 10.1007/s13534-023-00286-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 05/04/2023] [Accepted: 05/14/2023] [Indexed: 08/01/2023] Open
Abstract
Brain-computer interfaces (BCI) translate brain signals into artificial output to restore or replace natural central nervous system (CNS) functions. Multiple processes, including sensorimotor integration, decision-making, motor planning, execution, and updating, are involved in any movement. For example, a BCI may be better able to restore naturalistic motor behaviors if it uses signals from multiple brain areas and decodes natural behaviors' cognitive and motor aspects. This review provides an overview of the preliminary information necessary to plan a BCI project focusing on intracortical implants in primates. Since the brain structure and areas of non-human primates (NHP) are similar to humans, exploring the result of NHP studies will eventually benefit human BCI studies. The different types of BCI systems based on the target cortical area, types of signals, and decoding methods will be discussed. In addition, various successful state-of-the-art cases will be reviewed in more detail, focusing on the general algorithm followed in the real-time system. Finally, an outlook for improving the current BCI research studies will be debated.
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Affiliation(s)
- Alireza Rouzitalab
- School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 6N5 Canada
- The Ottawa Hospital Research Institute, Ottawa, ON Canada
| | | | - Jeongwon Park
- School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 6N5 Canada
- Department of Electrical and Biomedical Engineering, University of Nevada, Reno, NV 89557 USA
| | - Adam J. Sachs
- The Ottawa Hospital Research Institute, Ottawa, ON Canada
- The University of Ottawa Brain and Mind Research Institute, Ottawa, ON Canada
- Division of Neurosurgery, Department of Surgery, The Ottawa Hospital, Ottawa, ON Canada
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4
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Corrigan BW, Gulli RA, Doucet G, Mahmoudian B, Abbass M, Roussy M, Luna R, Sachs AJ, Martinez‐Trujillo JC. View cells in the hippocampus and prefrontal cortex of macaques during virtual navigation. Hippocampus 2023; 33:573-585. [PMID: 37002559 DOI: 10.1002/hipo.23534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/17/2023] [Accepted: 03/21/2023] [Indexed: 04/03/2023]
Abstract
Cells selectively activated by a particular view of an environment have been found in the primate hippocampus (HPC). Whether view cells are present in other brain areas, and how view selectivity interacts with other variables such as object features and place remain unclear. Here, we explore these issues by recording the responses of neurons in the HPC and the lateral prefrontal cortex (LPFC) of rhesus macaques performing a task in which they learn new context-object associations while navigating a virtual environment using a joystick. We measured neuronal responses at different locations in a virtual maze where animals freely directed gaze to different regions of the visual scenes. We show that specific views containing task relevant objects selectively activated a proportion of HPC units, and an even higher proportion of LPFC units. Place selectivity was scarce and generally dependent on view. Many view cells were not affected by changing the object color or the context cue, two task relevant features. However, a small proportion of view cells showed selectivity for these two features. Our results show that during navigation in a virtual environment with complex and dynamic visual stimuli, view cells are found in both the HPC and the LPFC. View cells may have developed as a multiarea specialization in diurnal primates to encode the complexities and layouts of the environment through gaze exploration which ultimately enables building cognitive maps of space that guide navigation.
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Affiliation(s)
- Benjamin W. Corrigan
- Department of Physiology and Pharmacology University of Western Ontario London Ontario Canada
| | - Roberto A. Gulli
- Zuckerman Mind Brain Behavior Institute Columbia University New York New York USA
- Center for Theoretical Neuroscience Columbia University New York New York USA
| | - Guillaume Doucet
- The Ottawa Hospital University of Ottawa Ottawa Ontario Canada
- Realize Medical Ottawa Ontario Canada
| | - Borna Mahmoudian
- Department of Physiology and Pharmacology University of Western Ontario London Ontario Canada
| | - Mohamad Abbass
- Western University Department of Clinical Neurological Sciences, London Health Sciences Centre Western University London Ontario Canada
| | - Megan Roussy
- Department of Physiology and Pharmacology University of Western Ontario London Ontario Canada
- National Science and Engineering Research Council Ottawa Ontario Canada
| | - Rogelio Luna
- Department of Physiology and Pharmacology University of Western Ontario London Ontario Canada
- Facultad de Medicina y Ciencias Biomédicas Universidad Autónoma de Chihuahua Chihuahua City Mexico
| | - Adam J. Sachs
- The Ottawa Hospital University of Ottawa Ottawa Ontario Canada
| | - Julio C. Martinez‐Trujillo
- Department of Physiology and Pharmacology University of Western Ontario London Ontario Canada
- Department of Psychiatry, Schulich School of Medicine and Dentistry University of Western Ontario London Ontario Canada
- Western Institute for Neuroscience University of Western Ontario London Ontario Canada
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5
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Johnston R, Abbass M, Corrigan B, Gulli R, Martinez-Trujillo J, Sachs A. Decoding spatial locations from primate lateral prefrontal cortex neural activity during virtual navigation. J Neural Eng 2023; 20. [PMID: 36693278 DOI: 10.1088/1741-2552/acb5c2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 01/24/2023] [Indexed: 01/25/2023]
Abstract
Objective. Decoding the intended trajectories from brain signals using a brain-computer interface system could be used to improve the mobility of patients with disabilities.Approach. Neuronal activity associated with spatial locations was examined while macaques performed a navigation task within a virtual environment.Main results.Here, we provide proof of principle that multi-unit spiking activity recorded from the lateral prefrontal cortex (LPFC) of non-human primates can be used to predict the location of a subject in a virtual maze during a navigation task. The spatial positions within the maze that require a choice or are associated with relevant task events can be better predicted than the locations where no relevant events occur. Importantly, within a task epoch of a single trial, multiple locations along the maze can be independently identified using a support vector machine model.Significance. Considering that the LPFC of macaques and humans share similar properties, our results suggest that this area could be a valuable implant location for an intracortical brain-computer interface system used for spatial navigation in patients with disabilities.
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Affiliation(s)
- Renée Johnston
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada.,Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Mohamad Abbass
- Department of Clinical Neurological Sciences, London Health Sciences Centre, Western University, London, ON, Canada.,Western Institute for Neuroscience, Western University, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Benjamin Corrigan
- Western Institute for Neuroscience, Western University, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Roberto Gulli
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States of America.,Center for Theoretical Neuroscience, Columbia University, New York, NY, United States of America
| | - Julio Martinez-Trujillo
- Western Institute for Neuroscience, Western University, London, ON, Canada.,Department of Physiology, Pharmacology, and Psychiatry, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Adam Sachs
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada.,Division of Neurosurgery, Ottawa Hospital Research Institute, Ottawa, ON, Canada
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6
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Tremblay S, Testard C, DiTullio RW, Inchauspé J, Petrides M. Neural cognitive signals during spontaneous movements in the macaque. Nat Neurosci 2023; 26:295-305. [PMID: 36536242 DOI: 10.1038/s41593-022-01220-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 10/27/2022] [Indexed: 12/24/2022]
Abstract
The single-neuron basis of cognitive processing in primates has mostly been studied in laboratory settings where movements are severely restricted. It is unclear, therefore, how natural movements might affect neural signatures of cognition in the brain. Moreover, studies in mice indicate that body movements, when measured, account for most of the neural dynamics in the cortex. To examine these issues, we recorded from single-neuron ensembles in the prefrontal cortex in moving monkeys performing a cognitive task and characterized eye, head and body movements using video tracking. Despite considerable trial-to-trial movement variability, single-neuron tuning could be precisely measured and decision signals accurately decoded on a single-trial basis. Creating or abolishing spontaneous movements through head restraint and task manipulations had no measurable impact on neural responses. However, encoding models showed that uninstructed movements explained as much neural variance as task variables, with most movements aligned to task events. These results demonstrate that cognitive signals in the cortex are robust to natural movements, but also that unmeasured movements are potential confounds in cognitive neurophysiology experiments.
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Affiliation(s)
- Sébastien Tremblay
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA, USA.
| | - Camille Testard
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA, USA
| | - Ron W DiTullio
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA, USA
| | - Jeanne Inchauspé
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Michael Petrides
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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7
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Roussy M, Corrigan B, Luna R, Gulli RA, Sachs AJ, Palaniyappan L, Martinez-Trujillo JC. Stable Working Memory and Perceptual Representations in Macaque Lateral Prefrontal Cortex during Naturalistic Vision. J Neurosci 2022; 42:8328-8342. [PMID: 36195438 PMCID: PMC9653275 DOI: 10.1523/jneurosci.0597-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 06/19/2022] [Accepted: 08/03/2022] [Indexed: 11/21/2022] Open
Abstract
Primates use perceptual and mnemonic visuospatial representations to perform everyday functions. Neurons in the lateral prefrontal cortex (LPFC) have been shown to encode both of these representations during tasks where eye movements are strictly controlled and visual stimuli are reduced in complexity. This raises the question of whether perceptual and mnemonic representations encoded by LPFC neurons remain robust during naturalistic vision-in the presence of a rich visual scenery and during eye movements. Here we investigate this issue by training macaque monkeys to perform working memory and perception tasks in a visually complex virtual environment that requires navigation using a joystick and allows for free visual exploration of the scene. We recorded the activity of 3950 neurons in the LPFC (areas 8a and 9/46) of two male rhesus macaques using multielectrode arrays, and measured eye movements using video tracking. We found that navigation trajectories to target locations and eye movement behavior differed between the perception and working memory tasks, suggesting that animals used different behavioral strategies. Single neurons were tuned to target location during cue encoding and working memory delay, and neural ensemble activity was predictive of the behavior of the animals. Neural decoding of the target location was stable throughout the working memory delay epoch. However, neural representations of similar target locations differed between the working memory and perception tasks. These findings indicate that during naturalistic vision, LPFC neurons maintain robust and distinct neural codes for mnemonic and perceptual visuospatial representations.SIGNIFICANCE STATEMENT We show that lateral prefrontal cortex neurons encode working memory and perceptual representations during a naturalistic task set in a virtual environment. We show that despite eye movement and complex visual input, neurons maintain robust working memory representations of space, which are distinct from neuronal representations for perception. We further provide novel insight into the use of virtual environments to construct behavioral tasks for electrophysiological experiments.
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Affiliation(s)
- Megan Roussy
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5C1, Canada
- Robarts Research Institute, Western University, London, Ontario N6A 3K7, Canada
- Department of Psychiatry, McGill University, Montreal, Quebec H3A 1A1, Canada
| | - Benjamin Corrigan
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5C1, Canada
- Robarts Research Institute, Western University, London, Ontario N6A 3K7, Canada
| | - Rogelio Luna
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5C1, Canada
- Robarts Research Institute, Western University, London, Ontario N6A 3K7, Canada
| | - Roberto A Gulli
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, New York 10027
| | - Adam J Sachs
- The Ottawa Hospital, University of Ottawa, Ottawa, Ontario K1H 8L6, Canada
| | - Lena Palaniyappan
- Department of Psychiatry, McGill University, Montreal, Quebec H3A 1A1, Canada
- Centre for Youth Mental Health, Douglas Mental Health University Institute, Montreal, Quebec H4H 1R3, Canada
| | - Julio C Martinez-Trujillo
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5C1, Canada
- Robarts Research Institute, Western University, London, Ontario N6A 3K7, Canada
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8
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Severe distortion in the representation of foveal visual image locations in short-term memory. Proc Natl Acad Sci U S A 2022; 119:e2121860119. [PMID: 35675430 PMCID: PMC9214507 DOI: 10.1073/pnas.2121860119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The foveal visual image region provides the human visual system with the highest acuity. However, it is unclear whether such a high fidelity representational advantage is maintained when foveal image locations are committed to short-term memory. Here, we describe a paradoxically large distortion in foveal target location recall by humans. We briefly presented small, but high contrast, points of light at eccentricities ranging from 0.1 to 12°, while subjects maintained their line of sight on a stable target. After a brief memory period, the subjects indicated the remembered target locations via computer controlled cursors. The biggest localization errors, in terms of both directional deviations and amplitude percentage overshoots or undershoots, occurred for the most foveal targets, and such distortions were still present, albeit with qualitatively different patterns, when subjects shifted their gaze to indicate the remembered target locations. Foveal visual images are severely distorted in short-term memory.
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9
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Xie Y, Liu YH, Constantinidis C, Zhou X. Neural Mechanisms of Working Memory Accuracy Revealed by Recurrent Neural Networks. Front Syst Neurosci 2022; 16:760864. [PMID: 35237134 PMCID: PMC8883483 DOI: 10.3389/fnsys.2022.760864] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 01/18/2022] [Indexed: 11/17/2022] Open
Abstract
Understanding the neural mechanisms of working memory has been a long-standing Neuroscience goal. Bump attractor models have been used to simulate persistent activity generated in the prefrontal cortex during working memory tasks and to study the relationship between activity and behavior. How realistic the assumptions of these models are has been a matter of debate. Here, we relied on an alternative strategy to gain insights into the computational principles behind the generation of persistent activity and on whether current models capture some universal computational principles. We trained Recurrent Neural Networks (RNNs) to perform spatial working memory tasks and examined what aspects of RNN activity accounted for working memory performance. Furthermore, we compared activity in fully trained networks and immature networks, achieving only imperfect performance. We thus examined the relationship between the trial-to-trial variability of responses simulated by the network and different aspects of unit activity as a way of identifying the critical parameters of memory maintenance. Properties that spontaneously emerged in the artificial network strongly resembled persistent activity of prefrontal neurons. Most importantly, these included drift of network activity during the course of a trial that was causal to the behavior of the network. As a consequence, delay period firing rate and behavior were positively correlated, in strong analogy to experimental results from the prefrontal cortex. These findings reveal that delay period activity is computationally efficient in maintaining working memory, as evidenced by unbiased optimization of parameters in artificial neural networks, oblivious to the properties of prefrontal neurons.
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Affiliation(s)
- Yuanqi Xie
- Department of Computer Science, Vanderbilt University, Nashville, TN, United States
| | - Yichen Henry Liu
- Department of Computer Science, Vanderbilt University, Nashville, TN, United States
| | - Christos Constantinidis
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
- Neuroscience Program, Vanderbilt University, Nashville, TN, United States
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Xin Zhou
- Department of Computer Science, Vanderbilt University, Nashville, TN, United States
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
- Data Science Institute, Vanderbilt University, Nashville, TN, United States
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10
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Roussy M, Mendoza-Halliday D, Martinez-Trujillo JC. Neural Substrates of Visual Perception and Working Memory: Two Sides of the Same Coin or Two Different Coins? Front Neural Circuits 2021; 15:764177. [PMID: 34899197 PMCID: PMC8662382 DOI: 10.3389/fncir.2021.764177] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/25/2021] [Indexed: 11/18/2022] Open
Abstract
Visual perception occurs when a set of physical signals emanating from the environment enter the visual system and the brain interprets such signals as a percept. Visual working memory occurs when the brain produces and maintains a mental representation of a percept while the physical signals corresponding to that percept are not available. Early studies in humans and non-human primates demonstrated that lesions of the prefrontal cortex impair performance during visual working memory tasks but not during perceptual tasks. These studies attributed a fundamental role in working memory and a lesser role in visual perception to the prefrontal cortex. Indeed, single cell recording studies have found that neurons in the lateral prefrontal cortex of macaques encode working memory representations via persistent firing, validating the results of lesion studies. However, other studies have reported that neurons in some areas of the parietal and temporal lobe-classically associated with visual perception-similarly encode working memory representations via persistent firing. This prompted a line of enquiry about the role of the prefrontal and other associative cortices in working memory and perception. Here, we review evidence from single neuron studies in macaque monkeys examining working memory representations across different areas of the visual hierarchy and link them to studies examining the role of the same areas in visual perception. We conclude that neurons in early visual areas of both ventral (V1-V2-V4) and dorsal (V1-V3-MT) visual pathways of macaques mainly encode perceptual signals. On the other hand, areas downstream from V4 and MT contain subpopulations of neurons that encode both perceptual and/or working memory signals. Differences in cortical architecture (neuronal types, layer composition, and synaptic density and distribution) may be linked to the differential encoding of perceptual and working memory signals between early visual areas and higher association areas.
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Affiliation(s)
- Megan Roussy
- Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, Robarts Research Institute, University of Western Ontario, London, ON, Canada
| | - Diego Mendoza-Halliday
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Julio C. Martinez-Trujillo
- Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, Robarts Research Institute, University of Western Ontario, London, ON, Canada
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11
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Zhao P, Lv H, Guo P, Su Y, Liu M, Wang Y, Hua H, Kang S. Altered Brain Functional Connectivity at Resting-State in Patients With Non-arteritic Anterior Ischemic Optic Neuropathy. Front Neurosci 2021; 15:712256. [PMID: 34658763 PMCID: PMC8517223 DOI: 10.3389/fnins.2021.712256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/09/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose: To investigate the possible changes in functional connectivity (FC) in patients with non-arteritic anterior ischemic optic neuropathy (NAION) using resting-state functional MRI (fMRI). Methods: Thirty-one NAION patients and 31 healthy controls were recruited and underwent resting-state fMRI scans. Regions of interest (ROIs) were defined as bilateral Brodmann’s area 17 (BA17). FC analysis was performed between the ROIs and the rest of the brain regions, and the between group comparisons of FC were performed. We conducted correlation analysis between the FC changes and the clinical variables in NAION patients. Results: Compared with healthy controls, patients with NAION showed significantly decreased FC between the left BA17 and the right inferior frontal gyrus, left caudate nucleus. As for the right BA17, patients exhibited significantly increased FC with the left olfactory gyrus and decreased FC with the right superior frontal gyrus (SFG), right insula. Moreover, FC values between the right insula and the right BA17 were positively correlated with the right side of mean sensitivity in the central visual field (r = 0.52, P < 0.01) and negatively correlated with the right side of mean defect in the central visual field (r = −0.55, P < 0.01). Conclusion: Our study indicated that patients with NAION showed significantly abnormal functional reorganization between the primary visual cortex and several other brain regions not directly related to visual function, which supports that NAION may not only be an ophthalmic disease but also a neuro-ophthalmological disease.
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Affiliation(s)
- Pengbo Zhao
- Department of Ophthalmology, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Han Lv
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Pengde Guo
- Department of Radiology, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Yan Su
- Department of Ophthalmology, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Ming Liu
- Department of Radiology, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Yan Wang
- Department of Radiology, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Haiqin Hua
- Department of Radiology, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Shaohong Kang
- Department of Radiology, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
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12
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Jiang L, Leung HC. Errors in visuospatial working memory across space and time. Sci Rep 2021; 11:14449. [PMID: 34262103 PMCID: PMC8280190 DOI: 10.1038/s41598-021-93858-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 06/25/2021] [Indexed: 11/27/2022] Open
Abstract
Visuospatial working memory (VSWM) involves cortical regions along the dorsal visual pathway, which are topographically organized with respect to the visual space. However, it remains unclear how such functional organization may constrain VSWM behavior across space and time. Here, we systematically mapped VSWM performance across the 2-dimensional (2D) space in various retention intervals in human subjects using the memory-guided and visually guided saccade tasks in two experiments. Relative to visually guided saccades, memory-guided saccades showed significant increases in unsystematic errors, or response variability, with increasing target eccentricity (3°-13° of visual angle). Unsystematic errors also increased with increasing delay (1.5-3 s, Experiment 1; 0.5-5 s, Experiment 2), while there was little or no interaction between delay and eccentricity. Continuous bump attractor modeling suggested neurophysiological and functional organization factors in the increasing unsystematic errors in VSWM across space and time. These findings indicate that: (1) VSWM representation may be limited by the functional topology of the visual pathway for the 2D space; (2) Unsystematic errors may reflect accumulated noise from memory maintenance while systematic errors may originate from non-mnemonic processes such as noisy sensorimotor transformation; (3) There may be independent mechanisms supporting the spatial and temporal processing of VSWM.
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Affiliation(s)
- Linjing Jiang
- Integrative Neuroscience Program, Department of Psychology, Stony Brook University, Stony Brook, NY, 11794, USA.
| | - Hoi-Chung Leung
- Integrative Neuroscience Program, Department of Psychology, Stony Brook University, Stony Brook, NY, 11794, USA.
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13
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Papadimitriou C, Holmes CD, Snyder LH. Primate Spatial Memory Cells Become Tuned Early and Lose Tuning at Cell-Specific Times. Cereb Cortex 2021; 31:4206-4219. [PMID: 33866356 DOI: 10.1093/cercor/bhab079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 01/28/2021] [Accepted: 02/20/2021] [Indexed: 11/14/2022] Open
Abstract
Working memory, the ability to maintain and transform information, is critical for cognition. Spatial working memory is particularly well studied. The premier model for spatial memory is the continuous attractor network, which posits that cells maintain constant activity over memory periods. Alternative models propose complex dynamics that result in a variety of cell activity time courses. We recorded from neurons in the frontal eye fields and dorsolateral prefrontal cortex of 2 macaques during long (5-15 s) memory periods. We found that memory cells turn on early after stimulus presentation, sustain activity for distinct and fixed lengths of time, then turn off and stay off for the remainder of the memory period. These dynamics are more complex than the dynamics of a canonical bump attractor network model (either decaying or nondecaying) but more constrained than the dynamics of fully heterogeneous memory models. We speculate that memory may be supported by multiple attractor networks working in parallel, with each network having its own characteristic mean turn-off time such that mnemonic resources are gradually freed up over time.
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Affiliation(s)
- Charalampos Papadimitriou
- Department of Neuroscience, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Charles D Holmes
- Department of Neuroscience, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Lawrence H Snyder
- Department of Neuroscience, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
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14
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Tong Y, Huang X, Qi CX, Shen Y. Assessment of spontaneous brain activity patterns in patients with iridocyclitis: a resting-state study. Neuroreport 2021; 32:612-620. [PMID: 33789337 DOI: 10.1097/wnr.0000000000001631] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Several studies demonstrated that patients with iridocyclitis were associated with vision loss and cognitive decline, whereas alterations in spontaneous brain activity occur in iridocyclitis patients remains unknown. The study aimed to explore spontaneous brain activity changes in iridocyclitis patients. Twenty-six patients with iridocyclitis and 26 healthy controls were finally included in our study. Resting-state MRI (rs-MRI) scan was conducted on both groups and the whole brain amplitude of low-frequency fluctuations (ALFFs) value was collected to assess differences in spontaneous brain activity. A receiver operating characteristic (ROC) curve was analyzed to distinguish between the fMRI data of patients with iridocyclitis and healthy controls. Patients with iridocyclitis showed significantly lower ALFF values in the right inferior parietal lobule, right calcarine, right superior temporal gyrus and right precentral gyrus compared to healthy controls and significantly higher ALFF values in the left superior frontal gyrus (P < 0.01, false discovery rate correction). The ROC curve analysis of different brain areas showed that the accuracies of ALFF value specificity between the iridocyclitis and healthy controls of the area under the curve were over 0.8. Our study highlighted an altered spontaneous activity in multiple brain regions, including the visual cortex, default-mode network, auditory area and sensorimotor areas in iridocyclitis. This may provide valuable information about underlying pathogenic mechanisms of iridocyclitis. These findings also indicate that rs-fMRI serves as a potential tool in the disease detection and evaluation of neurologic impairment in iridocyclitis.
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Affiliation(s)
- Yan Tong
- Eye Center, Renmin Hospital of Wuhan University, Wuhan, Hubei
| | - Xin Huang
- Department of Ophthalmology, Jiangxi Provincial People's Hospital, Nanchang
| | - Chen-Xing Qi
- Eye Center, Renmin Hospital of Wuhan University, Wuhan, Hubei
| | - Yin Shen
- Eye Center, Renmin Hospital of Wuhan University, Wuhan, Hubei.,Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, Hubei, China
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15
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Khanna SB, Scott JA, Smith MA. Dynamic shifts of visual and saccadic signals in prefrontal cortical regions 8Ar and FEF. J Neurophysiol 2020; 124:1774-1791. [PMID: 33026949 DOI: 10.1152/jn.00669.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Active vision is a fundamental process by which primates gather information about the external world. Multiple brain regions have been studied in the context of simple active vision tasks in which a visual target's appearance is temporally separated from saccade execution. Most neurons have tight spatial registration between visual and saccadic signals, and in areas such as prefrontal cortex (PFC), some neurons show persistent delay activity that links visual and motor epochs and has been proposed as a basis for spatial working memory. Many PFC neurons also show rich dynamics, which have been attributed to alternative working memory codes and the representation of other task variables. Our study investigated the transition between processing a visual stimulus and generating an eye movement in populations of PFC neurons in macaque monkeys performing a memory guided saccade task. We found that neurons in two subregions of PFC, the frontal eye fields (FEF) and area 8Ar, differed in their dynamics and spatial response profiles. These dynamics could be attributed largely to shifts in the spatial profile of visual and motor responses in individual neurons. This led to visual and motor codes for particular spatial locations that were instantiated by different mixtures of neurons, which could be important in PFC's flexible role in multiple sensory, cognitive, and motor tasks.NEW & NOTEWORTHY A central question in neuroscience is how the brain transitions from sensory representations to motor outputs. The prefrontal cortex contains neurons that have long been implicated as important in this transition and in working memory. We found evidence for rich and diverse tuning in these neurons, which was often spatially misaligned between visual and saccadic responses. This feature may play an important role in flexible working memory capabilities.
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Affiliation(s)
- Sanjeev B Khanna
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania.,Center for the Neural Basis of Cognition, Pittsburgh, Pennsylvania.,Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Jonathan A Scott
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Matthew A Smith
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania.,Center for the Neural Basis of Cognition, Pittsburgh, Pennsylvania.,Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania.,Carnegie Mellon Neuroscience Institute, Pittsburgh, Pennsylvania
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16
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Giorgio A, Zhang J, Costantino F, De Stefano N, Frezzotti P. Altered Large-Scale Brain Functional Connectivity in Ocular Hypertension. Front Neurosci 2020; 14:146. [PMID: 32194370 PMCID: PMC7066214 DOI: 10.3389/fnins.2020.00146] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 02/05/2020] [Indexed: 11/13/2022] Open
Abstract
We hypothesized that assessment of brain connectivity may shed light on the underpinnings of ocular hypertension (OHT), characterized by raised intraocular pressure (IOP) and no typical glaucomatous findings. OHT carries a risk for future glaucoma development, thus representing a model of presymptomatic condition. In previous studies on glaucoma, we showed altered brain connectivity since the early stage and in case of normal IOP. In this pilot study, we used a multimodal MRI approach by modeling voxelwise measures of gray matter volume, anatomical connectivity along white matter(WM) tracts, and large-scale functional connectivity in OHT subjects (n = 18, age: 58.3 ± 9.8 years) and demographically matched normal controls (n = 29). While OHT brain had no structural alterations, it showed significantly decreased functional connectivity in key cognitive networks [default mode network, frontoparietal working memory network (WMN), ventral attention network (VAN), and salience network (SN)] and altered long-range functional connectivity, which was decreased between default mode and SNs and increased between primary and secondary visual networks (VN). Overall, such findings seem to delineate a complex neuroplasticity in the OHT brain, where decreased functional connectivity in non-visual networks may reflect a type of temporarily downregulated functional reserve while increased functional connectivity between VN may be viewed as a very early attempt of adaptive functional reorganization of the visual system.
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Affiliation(s)
- Antonio Giorgio
- Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy
| | - Jian Zhang
- Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy
| | - Francesco Costantino
- Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy
| | - Nicola De Stefano
- Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy
| | - Paolo Frezzotti
- Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy
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17
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Wang B, Yan T, Zhou J, Xie Y, Qiu J, Wang Y, Lu W. Altered fMRI-derived functional connectivity in patients with high-tension glaucoma. J Neuroradiol 2020; 48:94-98. [PMID: 32169470 DOI: 10.1016/j.neurad.2020.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 02/17/2020] [Accepted: 03/02/2020] [Indexed: 11/15/2022]
Abstract
BACKGROUND High-tension glaucoma (HTG) is associated with functional changes in the brain, and elevated intraocular pressure (IOP) is one of the major causes. PURPOSE To evaluate the effects of high IOP on the brain in patients with HTG by using resting-state functional magnetic resonance imaging (rs-fMRI). MATERIALS AND METHODS Thirty-six patients with HTG and 20 age- and gender-matched healthy controls (HCs) were recruited and underwent IOP examination and rs-fMRI scan. Voxel-wise functional connectivity (FC) values were obtained between the Brodmann Area (BA) 17 (primary visual cortex) and the rest of the brain, two-sample t test was performed between HTG group and HCs. Correlation analysis was performed between FC and clinical information. RESULTS Compared with HCs, HTG patients demonstrated decreased FC between BA 17 and the right precuneus gyrus, decreased FC between BA 17 and the right superior frontal gyrus (SFG) (GRF corrected at voxel level P<0.001 and cluster level P<0.05, two-tailed). FC between BA 17 and the right SFG showed significantly negative correlation with right eyes' IOP and mean IOP. CONCLUSION HTG patients had abnormal FC changes between the visual cortex and multiple functional brain regions related to visual sense, memory consolidation and cognitive processing, which provided image support for the pathophysiology research of HTG, and revealed new targets for the accurate treatment of HTG.
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Affiliation(s)
- Baojian Wang
- Department of Radiology, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Tingqin Yan
- Department of Ophthalmology, Taian City Central Hospital, Taian, China
| | - Jian Zhou
- Department of Radiology, Taian City Central Hospital, Taian, China
| | - Yuanzhong Xie
- Department of Radiology, Taian City Central Hospital, Taian, China
| | - Jianfeng Qiu
- Department of Radiology, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China; Medical Engineering and Technology Research Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China.
| | - Yi Wang
- Department of Ophthalmology, The Second Affiliated hospital of Shandong First Medical University, Taian, China.
| | - Weizhao Lu
- Department of Radiology, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China; Medical Engineering and Technology Research Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China.
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18
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Persistent Spiking Activity Underlies Working Memory. J Neurosci 2019; 38:7020-7028. [PMID: 30089641 DOI: 10.1523/jneurosci.2486-17.2018] [Citation(s) in RCA: 164] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 05/16/2018] [Accepted: 05/25/2018] [Indexed: 01/10/2023] Open
Abstract
Persistent activity generated in the PFC during the delay period of working memory tasks represents information about stimuli held in memory and determines working memory performance. Alternative models of working memory, depending on the rhythmicity of discharges or exclusively on short-term synaptic plasticity, are inconsistent with the neurophysiological data.Dual Perspectives Companion Paper:Working Memory: Delay Activity, Yes! Persistent Activity? Maybe Not, by Mikael Lundqvist, Pawel Herman, and Earl K. Miller.
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19
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Wang Y, Lu W, Yan T, Zhou J, Xie Y, Yuan J, Liu G, Teng Y, Han W, Chen D, Qiu J. Functional MRI reveals effects of high intraocular pressure on central nervous system in high-tension glaucoma patients. Acta Ophthalmol 2019; 97:e341-e348. [PMID: 30801975 DOI: 10.1111/aos.14027] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 12/29/2018] [Indexed: 12/22/2022]
Abstract
PURPOSE To evaluate the effects of high intraocular pressure (IOP) on central nervous system in patients with high-tension glaucoma (HTG) by using resting-state functional magnetic resonance imaging (rs-fMRI). METHODS Thirty-six patients with HTG and twenty age- and gender-matched healthy controls (HCs) were recruited and underwent IOP measurement and rs-fMRI scan. The whole brain regional homogeneity (ReHo) value was calculated among the enrolled subjects. Two-sample t tests with permutation test and threshold-free cluster enhancement was performed between HTG group and HCs. Correlation analyses between IOP and ReHo values were conducted. RESULTS Compared with HCs, HTG group showed increased ReHo values in the left lobule 8 of cerebellar hemisphere, left lobule 4 and 5 of cerebellar hemisphere and left fusiform gyrus (FG) (p < 0.05). HTG group showed decreased ReHo value in the left middle frontal gyrus (MFG) (p < 0.05). Intraocular pressure of the left eye in HTG group experienced a significant positive correlation with ReHo value of the left FG (r = 0.370, p = 0.026), IOP of the right eye in HTG group showed a significant negative correlation with ReHo value in the left MFG (r = -0.421, p = 0.011). CONCLUSION Resting-state fMRI ReHo analyses associated elevated IOP with abnormal regional activity in several brain regions related to higher visual function and visual memory consolidation. High-tension glaucoma patients also showed diminished integration of visual information and cerebellar function. These results may provide imaging support for pathophysiological research of HTG and may reveal new targets for the accurate treatment of HTG.
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Affiliation(s)
- Yi Wang
- Department of Ophthalmology Affiliated Hospital of Taishan Medical University Taian China
- Department of Ophthalmology Taishan Medical University Taian China
- Institute of Opmetry Taishan Medical University Taian China
| | - Weizhao Lu
- Medical Engineering and Technology Research Center Taishan Medical University Taian China
- Department of Radiology Taishan Medical University Taian China
- Imaging‐X Joint Laboratory Taian China
| | - Tingqin Yan
- Department of Ophthalmology Taian City Central Hospital Tai China
| | - Jian Zhou
- Department of Radiology Taian City Central Hospital Tai China
| | - Yuanzhong Xie
- Department of Radiology Taian City Central Hospital Tai China
| | - Jiumin Yuan
- Department of Ophthalmology Affiliated Hospital of Taishan Medical University Taian China
- Department of Ophthalmology Taishan Medical University Taian China
- Institute of Opmetry Taishan Medical University Taian China
| | - Guangling Liu
- Department of Ophthalmology Affiliated Hospital of Taishan Medical University Taian China
- Department of Ophthalmology Taishan Medical University Taian China
- Institute of Opmetry Taishan Medical University Taian China
| | - Yufang Teng
- Department of Ophthalmology Affiliated Hospital of Taishan Medical University Taian China
- Department of Ophthalmology Taishan Medical University Taian China
- Institute of Opmetry Taishan Medical University Taian China
| | - Wenhui Han
- Department of Ophthalmology Affiliated Hospital of Taishan Medical University Taian China
- Department of Ophthalmology Taishan Medical University Taian China
- Institute of Opmetry Taishan Medical University Taian China
| | - Di Chen
- Department of Ophthalmology Affiliated Hospital of Taishan Medical University Taian China
- Department of Ophthalmology Taishan Medical University Taian China
- Institute of Opmetry Taishan Medical University Taian China
| | - Jianfeng Qiu
- Medical Engineering and Technology Research Center Taishan Medical University Taian China
- Department of Radiology Taishan Medical University Taian China
- Imaging‐X Joint Laboratory Taian China
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20
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Duong L, Leavitt M, Pieper F, Sachs A, Martinez-Trujillo J. A Normalization Circuit Underlying Coding of Spatial Attention in Primate Lateral Prefrontal Cortex. eNeuro 2019; 6:ENEURO.0301-18.2019. [PMID: 31001577 PMCID: PMC6469883 DOI: 10.1523/eneuro.0301-18.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 02/14/2019] [Accepted: 02/25/2019] [Indexed: 11/26/2022] Open
Abstract
Lateral prefrontal cortex (LPFC) neurons signal the allocation of voluntary attention; however, the neural computations underlying this function remain unknown. To investigate this, we recorded from neuronal ensembles in the LPFC of two Macaca fascicularis performing a visuospatial attention task. LPFC neural responses to a single stimulus were normalized when additional stimuli/distracters appeared across the visual field and were well-characterized by an averaging computation. Deploying attention toward an individual stimulus surrounded by distracters shifted neural activity from an averaging regime toward a regime similar to that when the attended stimulus was presented in isolation (winner-take-all; WTA). However, attentional modulation is both qualitatively and quantitatively dependent on a neuron's visuospatial tuning. Our results show that during attentive vision, LPFC neuronal ensemble activity can be robustly read out by downstream areas to generate motor commands, and/or fed back into sensory areas to filter out distracter signals in favor of target signals.
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Affiliation(s)
- Lyndon Duong
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 3K7, Canada
- Robarts Research Institute, London, Ontario N6A 5B7, Canada
| | - Matthew Leavitt
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 3K7, Canada
- Robarts Research Institute, London, Ontario N6A 5B7, Canada
- Department of Physiology, McGill University, Quebec H3A 0G4, Canada Montreal
| | - Florian Pieper
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg 52 20246, Germany
| | - Adam Sachs
- The Ottawa Hospital, University of Ottawa, Ottawa, Ontario K1H 8L6, Canada
| | - Julio Martinez-Trujillo
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 3K7, Canada
- Robarts Research Institute, London, Ontario N6A 5B7, Canada
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21
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Liu S, Tse PU, Cavanagh P. Meridian interference reveals neural locus of motion-induced position shifts. J Neurophysiol 2018. [PMID: 29513148 DOI: 10.1152/jn.00876.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
When a Gabor patch moves along a path in one direction while its internal texture drifts orthogonally to this path, it can appear to deviate from its physical path by 45° or more. This double-drift illusion is different from other motion-induced position shift effects in several ways: it has an integration period of over a second; the illusory displacement that accumulates over a second or more is orthogonal to rather than along the motion path; the perceptual deviations are much larger; and they have little or no effect on eye movements to the target. In this study we investigated the underlying neural mechanisms of the motion integration and position processing for this double-drift stimulus by testing possible anatomical constraints on its magnitude. We found that the illusion was reduced at the vertical and horizontal meridians when the perceptual path would cross or be driven toward the meridian, but not at other locations or other motion directions. The disruption of the accumulation of the position error at both the horizontal and vertical meridians suggests a central role of quadrantic areas in the generation of this type of motion-induced position shift. NEW & NOTEWORTHY The remarkably strong double-drift illusion is disrupted at both the vertical and horizontal meridians. We propose that this finding is the behavioral consequence of the anatomical gaps at both meridians, suggesting that neural areas with quadrantic representations (e.g., V2, V3) are the initial locus of this motion-induced position shift. This result rules out V1 as the source of the illusion because it has an anatomical break only at the vertical meridian.
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Affiliation(s)
- Sirui Liu
- Department of Psychological and Brian Sciences, Dartmouth College , Hanover, New Hampshire
| | - Peter U Tse
- Department of Psychological and Brian Sciences, Dartmouth College , Hanover, New Hampshire
| | - Patrick Cavanagh
- Department of Psychological and Brian Sciences, Dartmouth College , Hanover, New Hampshire.,Department of Psychology, Glendon College , Toronto, Ontario , Canada
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22
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Tang H, Riley MR, Constantinidis C. Lateralization of Executive Function: Working Memory Advantage for Same Hemifield Stimuli in the Monkey. Front Neurosci 2017; 11:532. [PMID: 29018321 PMCID: PMC5623043 DOI: 10.3389/fnins.2017.00532] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 09/13/2017] [Indexed: 11/25/2022] Open
Abstract
Working memory capacity, the amount of information that may be maintained in mind over a period of seconds, is extremely limited, to a handful of items. Some evidence exists that the number of visual items that may be maintained in working memory is independent for the two hemifields. To test this idea, we trained monkeys to perform visual working memory tasks that required maintenance in memory of the locations and/or shapes of 3–5 visual stimuli. We then tested whether systematic performance differences were present for stimuli concentrated in the same hemifield, vs. distributed across hemifields. We found little evidence to support the expectation that working memory capacity is independent in the two hemifields. Instead, when an advantage of stimulus arrangement was present, it involved multiple stimuli presented in the same hemifield. This conclusion was consistent across variations of the task, performance levels, and apparent strategies adopted by individual subjects. This result suggests that factors such as grouping that favor processing of stimuli in relative proximity may counteract the benefits of independent processing in the two hemispheres. Our results reveal an important property of working memory and place constraints on models of working memory capacity.
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Affiliation(s)
- Hua Tang
- Department of Neurobiology & Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, United States.,School of Life Science and Institute of Life Science, Nanchang University, Nanchang, China
| | - Mitchell R Riley
- Department of Neurobiology & Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - Christos Constantinidis
- Department of Neurobiology & Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, United States
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