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5 Publications

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    07/08/22 | Neural Algorithms and Circuits for Motor Planning.
    Inagaki HK, Chen S, Daie K, Finkelstein A, Fontolan L, Romani S, Svoboda K
    Annual Review Neuroscience. 2022 Jul 08;45:249-271. doi: 10.1146/annurev-neuro-092021-121730

    The brain plans and executes volitional movements. The underlying patterns of neural population activity have been explored in the context of movements of the eyes, limbs, tongue, and head in nonhuman primates and rodents. How do networks of neurons produce the slow neural dynamics that prepare specific movements and the fast dynamics that ultimately initiate these movements? Recent work exploits rapid and calibrated perturbations of neural activity to test specific dynamical systems models that are capable of producing the observed neural activity. These joint experimental and computational studies show that cortical dynamics during motor planning reflect fixed points of neural activity (attractors). Subcortical control signals reshape and move attractors over multiple timescales, causing commitment to specific actions and rapid transitions to movement execution. Experiments in rodents are beginning to reveal how these algorithms are implemented at the level of brain-wide neural circuits.

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    02/22/22 | Neural Algorithms and Circuits for Motor Planning.
    Inagaki HK, Chen S, Daie K, Finklestein A, Fontolan L, Romani S, Svoboda K
    Annual Reviews Neuroscience. 2022 Feb 22:. doi: 10.1146/annurev-neuro-092021-121730

    The brain plans and executes volitional movements. The underlying patterns of neural population activity have been explored in the context of movements of the eyes, limbs, tongue, and head in nonhuman primates and rodents. How do networks of neurons produce the slow neural dynamics that prepare specific movements and the fast dynamics that ultimately initiate these movements? Recent work exploits rapid and calibrated perturbations of neural activity to test specific dynamical systems models that are capable of producing the observed neural activity. These joint experimental and computational studies show that cortical dynamics during motor planning reflect fixed points of neural activity (attractors). Subcortical control signals reshape and move attractors over multiple timescales, causing commitment to specific actions and rapid transitions to movement execution. Experiments in rodents are beginning to reveal how these algorithms are implemented at the level of brain-wide neural circuits. Expected final online publication date for the , Volume 45 is July 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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    06/01/21 | Attractor dynamics gate cortical information flow during decision-making.
    Finkelstein A, Fontolan L, Economo MN, Li N, Romani S, Svoboda K
    Nature Neuroscience. 2021 Jun 1;24(6):843-50. doi: 10.1038/s41593-021-00840-6

    Decisions are held in memory until enacted, which makes them potentially vulnerable to distracting sensory input. Gating of information flow from sensory to motor areas could protect memory from interference during decision-making, but the underlying network mechanisms are not understood. Here, we trained mice to detect optogenetic stimulation of the somatosensory cortex, with a delay separating sensation and action. During the delay, distracting stimuli lost influence on behavior over time, even though distractor-evoked neural activity percolated through the cortex without attenuation. Instead, choice-encoding activity in the motor cortex became progressively less sensitive to the impact of distractors. Reverse engineering of neural networks trained to reproduce motor cortex activity revealed that the reduction in sensitivity to distractors was caused by a growing separation in the neural activity space between attractors that encode alternative decisions. Our results show that communication between brain regions can be gated via attractor dynamics, which control the degree of commitment to an action.

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    02/06/19 | Discrete attractor dynamics underlies persistent activity in the frontal cortex.
    Inagaki HK, Fontolan L, Romani S, Svoboda K
    Nature. 2019 Feb 06;566(7743):212-7. doi: 10.1038/s41586-019-0919-7

    Short-term memories link events separated in time, such as past sensation and future actions. Short-term memories are correlated with slow neural dynamics, including selective persistent activity, which can be maintained over seconds. In a delayed response task that requires short-term memory, neurons in the mouse anterior lateral motor cortex (ALM) show persistent activity that instructs future actions. To determine the principles that underlie this persistent activity, here we combined intracellular and extracellular electrophysiology with optogenetic perturbations and network modelling. We show that during the delay epoch, the activity of ALM neurons moved towards discrete end points that correspond to specific movement directions. These end points were robust to transient shifts in ALM activity caused by optogenetic perturbations. Perturbations occasionally switched the population dynamics to the other end point, followed by incorrect actions. Our results show that discrete attractor dynamics underlie short-term memory related to motor planning.

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    04/25/18 | Low-dimensional and monotonic preparatory activity in mouse anterior lateral motor cortex.
    Inagaki HK, Inagaki M, Romani S, Svoboda K
    The Journal of Neuroscience : the official journal of the Society for Neuroscience. 2018 Apr 25;38(17):4163-85. doi: 10.1523/JNEUROSCI.3152-17.2018

    Neurons in multiple brain regions fire trains of action potentials anticipating specific movements, but this 'preparatory activity' has not been systematically compared across behavioral tasks. We compared preparatory activity in auditory and tactile delayed-response tasks in male mice. Skilled, directional licking was the motor output. The anterior lateral motor cortex (ALM) is necessary for motor planning in both tasks. Multiple features of ALM preparatory activity during the delay epoch were similar across tasks. First, majority of neurons showed direction-selective activity and spatially intermingled neurons were selective for either movement direction. Second, many cells showed mixed coding of sensory stimulus and licking direction, with a bias toward licking direction. Third, delay activity was monotonic and low-dimensional. Fourth, pairs of neurons with similar direction selectivity showed high spike-count correlations. Our study forms the foundation to analyze the neural circuit mechanisms underlying preparatory activity in a genetically tractable model organism.Short-term memories link events separated in time. Neurons in frontal cortex fire trains of action potentials anticipating specific movements, often seconds before the movement. This 'preparatory activity' has been observed in multiple brain regions, but has rarely been compared systematically across behavioral tasks in the same brain region. To identify common features of preparatory activity, we developed and compared preparatory activity in auditory and tactile delayed-response tasks in mice. The same cortical area is necessary for both tasks. Multiple features of preparatory activity, measured with high-density silicon probes, were similar across tasks. We find that preparatory activity is low-dimensional and monotonic. Our study forms the foundation to analyze the circuit mechanisms underlying preparatory activity in a genetically tractable model organism.

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