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  1. Article ; Online: Solving the binding problem: Assemblies form when neurons enhance their firing rate-they don't need to oscillate or synchronize.

    Roelfsema, Pieter R

    Neuron

    2023  Volume 111, Issue 7, Page(s) 1003–1019

    Abstract: When we look at an image, its features are represented in our visual system in a highly distributed manner, calling for a mechanism that binds them into coherent object representations. There have been different proposals for the neuronal mechanisms that ...

    Abstract When we look at an image, its features are represented in our visual system in a highly distributed manner, calling for a mechanism that binds them into coherent object representations. There have been different proposals for the neuronal mechanisms that can mediate binding. One hypothesis is that binding is achieved by oscillations that synchronize neurons representing features of the same perceptual object. This view allows separate communication channels between different brain areas. Another hypothesis is that binding of features that are represented in different brain regions occurs when the neurons in these areas that respond to the same object simultaneously enhance their firing rate, which would correspond to directing object-based attention to these features. This review summarizes evidence in favor of and against these two hypotheses, examining the neuronal correlates of binding and assessing the time course of perceptual grouping. I conclude that enhanced neuronal firing rates bind features into coherent object representations, whereas oscillations and synchrony are unrelated to binding.
    MeSH term(s) Brain ; Neurons/physiology ; Visual Perception/physiology
    Language English
    Publishing date 2023-04-01
    Publishing country United States
    Document type Journal Article ; Review ; Research Support, Non-U.S. Gov't
    ZDB-ID 808167-0
    ISSN 1097-4199 ; 0896-6273
    ISSN (online) 1097-4199
    ISSN 0896-6273
    DOI 10.1016/j.neuron.2023.03.016
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  2. Article ; Online: Writing to the Mind's Eye of the Blind.

    Roelfsema, Pieter R

    Cell

    2020  Volume 181, Issue 4, Page(s) 758–759

    Abstract: The implantation of electrodes on the visual cortex of blind individuals could lead to the restoration of a rudimentary form of sight. In this issue of Cell, Beauchamp et al. use electrical stimulation of the visual cortex to create visual perception of ... ...

    Abstract The implantation of electrodes on the visual cortex of blind individuals could lead to the restoration of a rudimentary form of sight. In this issue of Cell, Beauchamp et al. use electrical stimulation of the visual cortex to create visual perception of shapes.
    MeSH term(s) Eye ; Humans ; Visual Cortex ; Visual Perception ; Writing
    Language English
    Publishing date 2020-05-15
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Comment
    ZDB-ID 187009-9
    ISSN 1097-4172 ; 0092-8674
    ISSN (online) 1097-4172
    ISSN 0092-8674
    DOI 10.1016/j.cell.2020.03.014
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  3. Article ; Online: Recurrent neural networks that learn multi-step visual routines with reinforcement learning.

    Mollard, Sami / Wacongne, Catherine / Bohte, Sander M / Roelfsema, Pieter R

    PLoS computational biology

    2024  Volume 20, Issue 4, Page(s) e1012030

    Abstract: Many cognitive problems can be decomposed into series of subproblems that are solved sequentially by the brain. When subproblems are solved, relevant intermediate results need to be stored by neurons and propagated to the next subproblem, until the ... ...

    Abstract Many cognitive problems can be decomposed into series of subproblems that are solved sequentially by the brain. When subproblems are solved, relevant intermediate results need to be stored by neurons and propagated to the next subproblem, until the overarching goal has been completed. We will here consider visual tasks, which can be decomposed into sequences of elemental visual operations. Experimental evidence suggests that intermediate results of the elemental operations are stored in working memory as an enhancement of neural activity in the visual cortex. The focus of enhanced activity is then available for subsequent operations to act upon. The main question at stake is how the elemental operations and their sequencing can emerge in neural networks that are trained with only rewards, in a reinforcement learning setting. We here propose a new recurrent neural network architecture that can learn composite visual tasks that require the application of successive elemental operations. Specifically, we selected three tasks for which electrophysiological recordings of monkeys' visual cortex are available. To train the networks, we used RELEARNN, a biologically plausible four-factor Hebbian learning rule, which is local both in time and space. We report that networks learn elemental operations, such as contour grouping and visual search, and execute sequences of operations, solely based on the characteristics of the visual stimuli and the reward structure of a task. After training was completed, the activity of the units of the neural network elicited by behaviorally relevant image items was stronger than that elicited by irrelevant ones, just as has been observed in the visual cortex of monkeys solving the same tasks. Relevant information that needed to be exchanged between subroutines was maintained as a focus of enhanced activity and passed on to the subsequent subroutines. Our results demonstrate how a biologically plausible learning rule can train a recurrent neural network on multistep visual tasks.
    MeSH term(s) Animals ; Visual Cortex/physiology ; Neural Networks, Computer ; Reinforcement, Psychology ; Models, Neurological ; Computational Biology ; Memory, Short-Term/physiology ; Neurons/physiology ; Learning/physiology ; Visual Perception/physiology ; Macaca mulatta
    Language English
    Publishing date 2024-04-29
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2193340-6
    ISSN 1553-7358 ; 1553-734X
    ISSN (online) 1553-7358
    ISSN 1553-734X
    DOI 10.1371/journal.pcbi.1012030
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  4. Article ; Online: Flexible Polymer Electrodes for Stable Prosthetic Visual Perception in Mice.

    Orlemann, Corinne / Boehler, Christian / Kooijmans, Roxana N / Li, Bingshuo / Asplund, Maria / Roelfsema, Pieter R

    Advanced healthcare materials

    2024  , Page(s) e2304169

    Abstract: Brain interfaces that can stimulate neurons, cause minimal damage, and work for a long time will be central for future neuroprosthetics. Here, the long-term performance of highly flexible, thin polyimide shanks with several small (<15 µm) electrodes ... ...

    Abstract Brain interfaces that can stimulate neurons, cause minimal damage, and work for a long time will be central for future neuroprosthetics. Here, the long-term performance of highly flexible, thin polyimide shanks with several small (<15 µm) electrodes during electrical microstimulation of the visual cortex, is reported. The electrodes exhibit a remarkable stability when several billions of electrical pulses are applied in vitro. When the devices are implanted in the primary visual cortex (area V1) of mice and the animals are trained to detect electrical microstimulation, it is found that the perceptual thresholds are 2-20 microamperes (µA), which is far below the maximal currents that the electrodes can withstand. The long-term functionality of the devices in vivo is excellent, with stable performance for up to more than a year and little damage to the brain tissue. These results demonstrate the potential of thin floating electrodes for the long-term restoration of lost sensory functions.
    Language English
    Publishing date 2024-02-07
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2649576-4
    ISSN 2192-2659 ; 2192-2640
    ISSN (online) 2192-2659
    ISSN 2192-2640
    DOI 10.1002/adhm.202304169
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  5. Article ; Online: Contextual drive of neuronal responses in mouse V1 in the absence of feedforward input.

    Kirchberger, Lisa / Mukherjee, Sreedeep / Self, Matthew W / Roelfsema, Pieter R

    Science advances

    2023  Volume 9, Issue 3, Page(s) eadd2498

    Abstract: Neurons in the primary visual cortex (V1) respond to stimuli in their receptive field (RF), which is defined by the feedforward input from the retina. However, V1 neurons are also sensitive to contextual information outside their RF, even if the RF ... ...

    Abstract Neurons in the primary visual cortex (V1) respond to stimuli in their receptive field (RF), which is defined by the feedforward input from the retina. However, V1 neurons are also sensitive to contextual information outside their RF, even if the RF itself is unstimulated. Here, we examined the cortical circuits for V1 contextual responses to gray disks superimposed on different backgrounds. Contextual responses began late and were strongest in the feedback-recipient layers of V1. They differed between the three main classes of inhibitory neurons, with particularly strong contextual drive of VIP neurons, indicating a contribution of disinhibitory circuits to contextual drive. Contextual drive was strongest when the gray disk was perceived as figure, occluding its background, rather than a hole. Our results link contextual drive in V1 to perceptual organization and provide previously unknown insight into how recurrent processing shapes the response of sensory neurons to facilitate figure perception.
    MeSH term(s) Mice ; Animals ; Visual Cortex/physiology ; Neurons/physiology ; Retina ; Neurons, Afferent ; Orientation/physiology ; Visual Perception/physiology ; Photic Stimulation/methods
    Language English
    Publishing date 2023-01-20
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2810933-8
    ISSN 2375-2548 ; 2375-2548
    ISSN (online) 2375-2548
    ISSN 2375-2548
    DOI 10.1126/sciadv.add2498
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  6. Article ; Online: Inversion of pop-out for a distracting feature dimension in monkey visual cortex.

    Klink, P Christiaan / Teeuwen, Rob R M / Lorteije, Jeannette A M / Roelfsema, Pieter R

    Proceedings of the National Academy of Sciences of the United States of America

    2023  Volume 120, Issue 9, Page(s) e2210839120

    Abstract: During visual search, it is important to reduce the interference of distracting objects in the scene. The neuronal responses elicited by the search target stimulus are typically enhanced. However, it is equally important to suppress the representations ... ...

    Abstract During visual search, it is important to reduce the interference of distracting objects in the scene. The neuronal responses elicited by the search target stimulus are typically enhanced. However, it is equally important to suppress the representations of distracting stimuli, especially if they are salient and capture attention. We trained monkeys to make an eye movement to a unique "pop-out" shape stimulus among an array of distracting stimuli. One of these distractors had a salient color that varied across trials and differed from the color of the other stimuli, causing it to also pop-out. The monkeys were able to select the pop-out shape target with high accuracy and actively avoided the pop-out color distractor. This behavioral pattern was reflected in the activity of neurons in area V4. Responses to the shape targets were enhanced, while the activity evoked by the pop-out color distractor was only briefly enhanced, directly followed by a sustained period of pronounced suppression. These behavioral and neuronal results demonstrate a cortical selection mechanism that rapidly inverts a pop-out signal to "pop-in" for an entire feature dimension thereby facilitating goal-directed visual search in the presence of salient distractors.
    MeSH term(s) Animals ; Color Perception/physiology ; Haplorhini ; Attention/physiology ; Eye Movements ; Visual Cortex/physiology ; Reaction Time/physiology ; Visual Perception/physiology
    Language English
    Publishing date 2023-02-22
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2210839120
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    Zs.A 1148: Show issues Location:
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  7. Article ; Online: Neuroscience: Figured Out by Feedback to the Thalamus.

    Self, Matthew W / Roelfsema, Pieter R

    Current biology : CB

    2019  Volume 29, Issue 12, Page(s) R574–R577

    Abstract: The lateral geniculate nucleus of the thalamus (LGN) is a relay nucleus between the retina and the visual cortex. A new brain imaging study shows that LGN activity is modulated by figure-ground organization, even when the figure and ground are presented ... ...

    Abstract The lateral geniculate nucleus of the thalamus (LGN) is a relay nucleus between the retina and the visual cortex. A new brain imaging study shows that LGN activity is modulated by figure-ground organization, even when the figure and ground are presented to different eyes: a hallmark of a cortical feedback effect.
    MeSH term(s) Attention ; Geniculate Bodies ; Humans ; Retina ; Thalamus ; Visual Cortex
    Language English
    Publishing date 2019-06-18
    Publishing country England
    Document type Journal Article ; Comment
    ZDB-ID 1071731-6
    ISSN 1879-0445 ; 0960-9822
    ISSN (online) 1879-0445
    ISSN 0960-9822
    DOI 10.1016/j.cub.2019.05.022
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  8. Article ; Online: Reply to 'Can neocortical feedback alter the sign of plasticity?'

    Roelfsema, Pieter R / Holtmaat, Anthony

    Nature reviews. Neuroscience

    2018  Volume 19, Issue 10, Page(s) 637–638

    MeSH term(s) Neocortex ; Neuronal Plasticity
    Language English
    Publishing date 2018-06-19
    Publishing country England
    Document type Letter ; Comment
    ZDB-ID 2034150-7
    ISSN 1471-0048 ; 1471-0048 ; 1471-003X
    ISSN (online) 1471-0048
    ISSN 1471-0048 ; 1471-003X
    DOI 10.1038/s41583-018-0048-6
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  9. Article ; Online: Control of synaptic plasticity in deep cortical networks.

    Roelfsema, Pieter R / Holtmaat, Anthony

    Nature reviews. Neuroscience

    2018  Volume 19, Issue 3, Page(s) 166–180

    Abstract: Humans and many other animals have an enormous capacity to learn about sensory stimuli and to master new skills. However, many of the mechanisms that enable us to learn remain to be understood. One of the greatest challenges of systems neuroscience is to ...

    Abstract Humans and many other animals have an enormous capacity to learn about sensory stimuli and to master new skills. However, many of the mechanisms that enable us to learn remain to be understood. One of the greatest challenges of systems neuroscience is to explain how synaptic connections change to support maximally adaptive behaviour. Here, we provide an overview of factors that determine the change in the strength of synapses, with a focus on synaptic plasticity in sensory cortices. We review the influence of neuromodulators and feedback connections in synaptic plasticity and suggest a specific framework in which these factors can interact to improve the functioning of the entire network.
    MeSH term(s) Animals ; Attention/physiology ; Cerebral Cortex/physiology ; Humans ; Learning/physiology ; Models, Neurological ; Neural Pathways/physiology ; Neuronal Plasticity ; Neurons/physiology ; Reward
    Language English
    Publishing date 2018-02-16
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 2034150-7
    ISSN 1471-0048 ; 1471-0048 ; 1471-003X
    ISSN (online) 1471-0048
    ISSN 1471-0048 ; 1471-003X
    DOI 10.1038/nrn.2018.6
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  10. Article ; Online: Object Selection by Automatic Spreading of Top-Down Attentional Signals in V1.

    Ekman, Matthias / Roelfsema, Pieter R / de Lange, Floris P

    The Journal of neuroscience : the official journal of the Society for Neuroscience

    2020  Volume 40, Issue 48, Page(s) 9250–9259

    Abstract: What is selected when attention is directed to a specific location of the visual field? Theories of object-based attention have suggested that when spatial attention is directed to part of an object, attention does not simply enhance the attended ... ...

    Abstract What is selected when attention is directed to a specific location of the visual field? Theories of object-based attention have suggested that when spatial attention is directed to part of an object, attention does not simply enhance the attended location but automatically spreads to enhance all locations that comprise the object. Here, we tested this hypothesis by reconstructing the distribution of attention from primary visual cortex (V1) population neuronal activity patterns in 24 human adults (17 female) using functional magnetic resonance imaging (fMRI) and population-based receptive field (prf) mapping. We find that attention spreads from a spatially cued location to the underlying object, and enhances all spatial locations that comprise the object. Importantly, this spreading was also evident when the object was not task relevant. These data suggest that attentional selection automatically operates at an object level, facilitating the reconstruction of coherent objects from fragmented representations in early visual cortex.
    MeSH term(s) Adult ; Attention/physiology ; Brain Mapping ; Cues ; Female ; Hemodynamics/physiology ; Humans ; Magnetic Resonance Imaging ; Male ; Photic Stimulation ; Reaction Time/physiology ; Space Perception/physiology ; Visual Cortex/diagnostic imaging ; Visual Cortex/physiology ; Visual Fields/physiology ; Visual Perception/physiology ; Young Adult
    Language English
    Publishing date 2020-10-21
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 604637-x
    ISSN 1529-2401 ; 0270-6474
    ISSN (online) 1529-2401
    ISSN 0270-6474
    DOI 10.1523/JNEUROSCI.0438-20.2020
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