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Veit Stuphorn - One of the best experts on this subject based on the ideXlab platform.
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inactivation of medial frontal cortex changes risk preference
Current Biology, 2018Co-Authors: Veit Stuphorn, Xiaomo ChenAbstract:Summary Humans and other animals need to make decisions under varying degrees of uncertainty. These decisions are strongly influenced by an individual’s risk preference; however, the neuronal circuitry by which risk preference shapes choice is still unclear [ 1 ]. Supplementary Eye Field (SEF), an oculomotor area within primate medial frontal cortex, is thought to be an essential part of the neuronal circuit underlying oculomotor decision making, including decisions under risk [ 2 , 3 , 4 , 5 ]. Consistent with this view, risk-related action value and monitoring signals have been observed in SEF [ 6 , 7 , 8 ]. However, such activity has also been observed in other frontal areas, including orbitofrontal [ 9 , 10 , 11 ], cingulate [ 12 , 13 , 14 ], and dorsal-lateral frontal cortex [ 15 ]. It is thus unknown whether the activity in SEF causally contributes to risky decisions, or whether it is merely a reflection of neural processes in other cortical regions. Here, we tested a causal role of SEF in risky oculomotor choices. We found that SEF inactivation strongly reduced the frequency of risky choices. This reduction was largely due to a reduced attraction to reward uncertainty and high reward gain, but not due to changes in the subjective estimation of reward probability or average expected reward. Moreover, SEF inactivation also led to increased sensitivity to differences between expected and actual reward during free choice. Nevertheless, it did not affect adjustments of decisions based on reward history.
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inactivation of medial frontal cortex changes risk preference
bioRxiv, 2018Co-Authors: Veit Stuphorn, Xiaomo ChenAbstract:Summary Humans and other animals need to make decisions under varying degrees of uncertainty. These decisions are strongly influenced by an individual’s risk preference, however the neuronal circuitry by which risk preference shapes choice is still unclear [1]. Supplementary Eye Field (SEF), an oculomotor area within primate medial frontal cortex, is thought to be an essential part of the neuronal circuit underlying oculomotor decision-making, including decisions under risk [2–5]. Consistent with this view, risk-related action value and monitoring signals have been observed in SEF [6–8]. However, such activity has also been observed in other frontal areas, including orbitofrontal [9–11], cingulate [12–14], and dorsal lateral frontal cortex [15]. It is thus unknown whether the activity in SEF causally contributes to risky decisions, or if it is merely a reflection of neural processes in other cortical regions. Here, we tested a causal role of SEF in risky oculomotor choices. We found that SEF inactivation strongly reduced the frequency of risky choices. This reduction was largely due to a reduced attraction to reward uncertainty and high reward gain, but not due to changes in the subjective estimation of reward probability or average expected reward. Moreover, SEF inactivation also led to increased sensitivity to differences between expected and actual reward during free choice. Nevertheless, it did not affect adjustments of decisions based on reward history.
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Sequential selection of economic good and action in medial frontal cortex of macaques during value-based decisions
eLife, 2015Co-Authors: Xiaomo Chen, Veit StuphornAbstract:Value-based decisions could rely either on the selection of desired economic goods or on the selection of the actions that will obtain the goods. We investigated this question by recording from the Supplementary Eye Field (SEF) of monkeys during a gambling task that allowed us to distinguish chosen good from chosen action signals. Analysis of the individual neuron activity, as well as of the population state-space dynamic, showed that SEF encodes first the chosen gamble option (the desired economic good) and only ~100 ms later the saccade that will obtain it (the chosen action). The action selection is likely driven by inhibitory interactions between different SEF neurons. Our results suggest that during value-based decisions, the selection of economic goods precedes and guides the selection of actions. The two selection steps serve different functions and can therefore not compensate for each other, even when information guiding both processes is given simultaneously.
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sequential selection of economic good and action in medial frontal cortex of macaques during value based decisions
eLife, 2015Co-Authors: Xiaomo Chen, Veit StuphornAbstract:Much of our decision making seems to involve selecting the best option from among those currently available, and then working out how to attain that particular outcome. However, while this might sound straightforward in principle, exactly how this process is organized within the brain is not entirely clear. One possibility is that the brain compares all the possible outcomes of a decision with each other before constructing a plan of action to achieve the most desirable of these. This is known as the 'goods-based' model of decision making. However, an alternative possibility is that the brain instead considers all the possible actions that could be performed at any given time. One specific action is then chosen based on a range of factors, including the potential outcomes that might result from each. This is an 'action-based' model of decision making. Chen and Stuphorn have now distinguished between these possibilities by training two monkeys to perform a gambling task. The animals learned to make Eye movements to one of two targets on a screen to earn a reward. The identity of the targets varied between trials, with some associated with larger rewards or a higher likelihood of receiving a reward than others. The location of the targets also changed in different trials, which meant that the choice of 'action' (moving the Eyes to the left or right) could be distinguished from the choice of 'goods' (the reward). By using electrodes to record from a region of the brain called the Supplementary Eye Field, which helps to control Eye movements, Chen and Stuphorn showed that the activity of neurons in this region predicted the monkeys’ decision-making behavior. Crucially, it did so in two stages: neurons first encoded the reward chosen by the monkey, before subsequently encoding the action that the monkey selected to obtain that outcome. These data argue against an action-based model of decision making because outcomes are encoded before actions. However, they also argue against a purely goods-based model. This is because all possible actions are encoded by the brain (including those that are subsequently rejected), with the highest levels of activity seen for the action that is ultimately selected. The data instead support a new model of decision making, in which outcomes and actions are selected sequentially via two independent brain circuits.
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Supplementary Eye Field Encodes Confidence in Decisions Under Risk
Cerebral Cortex, 2015Co-Authors: Veit StuphornAbstract:Choices are made with varying degrees of confidence, a cognitive signal representing the subjective belief in the optimality of the choice. Confidence has been mostly studied in the context of perceptual judgments, in which choice accuracy can be measured using objective criteria. Here, we study confidence in subjective value-based decisions. We recorded in the Supplementary Eye Field (SEF) of monkeys performing a gambling task, where they had to use subjective criteria for placing bets. We found neural signals in the SEF that explicitly represent choice confidence independent from reward expectation. This confidence signal appeared after the choice and diminished before the choice outcome. Most of this neuronal activity was negatively correlated with confidence, and was strongest in trials on which the monkey spontaneously withdrew his choice. Such confidence-related activity indicates that the SEF not only guides saccade selection, but also evaluates the likelihood that the choice was optimal. This internal evaluation influences decisions concerning the willingness to bear later costs that follow from the choice or to avoid them. More generally, our findings indicate that choice confidence is an integral component of all forms of decision-making, whether they are based on perceptual evidence or on value estimations.
Pierre Pouget - One of the best experts on this subject based on the ideXlab platform.
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Functional ultrasound imaging of the brain reveals propagation of task-related brain activity in behaving primates
Nature Communications, 2019Co-Authors: Alexandre Dizeux, Pierre Pouget, Marc Gesnik, Thomas Deffieux, Harry Ahnine, Kevin Blaize, Fabrice Arcizet, Serge Picaud, José-alain Sahel, Mickael TanterAbstract:Neuroimaging modalities such as MRI and EEG are able to record from the whole brain, but this comes at the price of either limited spatiotemporal resolution or limited sensitivity. Here, we show that functional ultrasound imaging (fUS) of the brain is able to assess local changes in cerebral blood volume during cognitive tasks, with sufficient temporal resolution to measure the directional propagation of signals. In two macaques, we observed an abrupt transient change in Supplementary Eye Field (SEF) activity when animals were required to modify their behaviour associated with a change of saccade tasks. SEF activation could be observed in a single trial, without averaging. Simultaneous imaging of anterior cingulate cortex and SEF revealed a time delay in the directional functional connectivity of 0.27 ± 0.07 s and 0.9 ± 0.2 s for both animals. Cerebral hemodynamics of large brain areas can be measured at high spatiotemporal resolution using fUS.
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frontal Eye Field in prosimian galagos intracortical microstimulation and tracing studies
The Journal of Comparative Neurology, 2018Co-Authors: Iwona Stepniewska, Pierre Pouget, Jon H. KaasAbstract:The frontal Eye Field (FEF) in prosimian primates was identified as a small cortical region, above and anterior to the anterior frontal sulcus, from which saccadic Eye movements were evoked with electrical stimulation. Tracer injections revealed FEF connections with cortical and subcortical structures participating in higher order visual processing. Ipsilateral cortical connections were the densest with adjoining parts of the dorsal premotor and prefrontal cortex (PFC). Label in a region corresponding to Supplementary Eye Field (SEF) of other primates, suggests the existence of SEF in galagos. Other connections were with ventral premotor cortex (PMV), the caudal half of posterior parietal cortex, cingulate cortex, visual areas within the superior temporal sulcus, and inferotemporal cortex. Callosal connections were mostly with the region of the FEF of another hemisphere, SEF, PFC and PMV. Most subcortical connections were ipsilateral, but some were bilateral. Dense bilateral connections were to caudate nuclei. Densest reciprocal ipsilateral connections were with the paralamellar portion of mediodorsal nucleus, intralaminar nuclei and magnocellular portion of ventral anterior nucleus. Other FEF connections were with the claustrum, reticular nucleus, zona incerta, lateral posterior and medial pulvinar nuclei, nucleus limitans, pretectal area, nucleus of Darkschewitsch, mesencephalic and pontine reticular formation and pontine nuclei. Surprisingly, the superior colliculus (SC) contained only sparse anterograde label. Although most FEF connections in galagos are similar to those in monkeys, the FEF-SC connections appear to be much less. This suggests that a major contribution of the FEF to visuomotor functions of SC emerged with the evolution of anthropoid primates. This article is protected by copyright. All rights reserved.
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transcranial ultrasonic stimulation modulates single neuron discharge in macaques performing an antisaccade task
Brain Stimulation, 2017Co-Authors: Nicolas Wattiez, Thomas Deffieux, Mickael Tanter, Charlotte Constans, Pierre M Daye, Jeanfrancois Aubry, Pierre PougetAbstract:Background: Low intensity transcranial ultrasonic stimulation (TUS) has been demonstrated to non-invasively and transiently stimulate the nervous system. Although US neuromodulation has appeared robust in rodent studies, the effects of US in large mammals and humans have been modest at best. In addition, there is a lack of direct recordings from the stimulated neurons in response to US. Our study investigates the magnitude of the US effects on neuronal discharge in awake behaving monkeys and thus fills the void on both fronts. Objective/Hypothesis: In this study, we demonstrate the feasibility of recording action potentials in the Supplementary Eye Field (SEF) as TUS is applied simultaneously to the frontal Eye Field (FEF) in macaques performing an antisaccade task. Results: We show that compared to a control stimulation in the visual cortex, SEF activity is significantly modulated shortly after TUS onset. Among all cell types 40% of neurons significantly changed their activity after TUS. Half of the neurons showed a transient increase of activity induced by TUS. Conclusion: Our study demonstrates that the neuromodulatory effects of non-invasive focused ultrasound can be assessed in real time in awake behaving monkeys by recording discharge activity from a brain region reciprocally connected with the stimulated region. The study opens the door for further parametric studies for fine-tuning the ultrasonic parameters. The ultrasonic effect could indeed be quantified based on the direct measurement of the intensity of the modulation induced on a single neuron in a freely performing animal. The technique should be readily reproducible in other primate laboratories studying brain function, both for exploratory and therapeutic purposes and to facilitate the development of future clinical TUS devices.
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Functional ultrasound imaging in awake non-human primates performing voluntary saccade
2017 IEEE International Ultrasonics Symposium (IUS), 2017Co-Authors: Alexandre Dizeux, Pierre Pouget, Nicolas Wattiez, Marc Gesnik, Thomas Deffieux, Mickael TanterAbstract:Functional ultrasound (fUS) is a novel technique for in vivo neuroimaging which allows to map subtle changes of the Cerebral Blood Volume (CBV) due to neurovascular coupling with a very high sensitivity, and thus map dynamics of brain activity [1]. In this study, we apply fUS to awake and behaving non-human primate to investigate the monitoring of saccadic Eye movement by the Supplementary Eye Field (SEF) brain region [2]. This represents the first fUS images in non-human primate, doing complex tasks, which generally remains very challenging to perform in an MRI environment in awake and behaving conditions.
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performance monitoring local Field potentials in the medial frontal cortex of primates Supplementary Eye Field
Journal of Neurophysiology, 2010Co-Authors: Erik E Emeric, Pierre Pouget, Melanie Leslie, Jeffrey D SchallAbstract:We describe intracranial local Field potentials (LFPs) recorded in the Supplementary Eye Field (SEF) of macaque monkeys performing a saccade countermanding task. The most prominent feature at 90% of the sites was a negative-going polarization evoked by a contralateral visual target. At roughly 50% of sites a negative-going polarization was observed preceding saccades, but in stop signal trials this polarization was not modulated in a manner sufficient to control saccade initiation. When saccades were canceled in stop signal trials, LFP modulation increased with the inferred magnitude of response conflict derived from the coactivation of gaze-shifting and gaze-holding neurons. At 30% of sites, a pronounced negative-going polarization occurred after errors. This negative polarity did not appear in unrewarded correct trials. Variations of response time with trial history were not related to any features of the LFP. The results provide new evidence that error-related and conflict-related but not feedback-related signals are convEyed by the LFP in the macaque SEF and are important for identifying the generator of the error-related negativity.
John Schlag - One of the best experts on this subject based on the ideXlab platform.
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Frames of reference for saccadic command tested by saccade collision in the Supplementary Eye Field.
Journal of Neurophysiology, 2006Co-Authors: Junghyun Park, Madeleine Schlag-rey, John SchlagAbstract:In what frame of reference does the Supplementary Eye Field (SEF) encode saccadic Eye movements? In this study, the “saccade collision” test was used to determine whether a saccade electrically evo...
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primate antisaccade ii Supplementary Eye Field neuronal activity predicts correct performance
Journal of Neurophysiology, 2004Co-Authors: Nelly Amador, Madeleine Schlagrey, John SchlagAbstract:Neuronal activities were recorded in the Supplementary Eye Field (SEF) of 3 macaque monkeys trained to perform antisaccades pseudorandomly interleaved with prosaccades, as instructed by the shape of a central fixation point. The prosaccade goal was indicated by a peripheral stimulus flashed anywhere on the screen, whereas the antisaccade goal was an unmarked site diametrically opposite the flashed stimulus. The visual cue was given immediately after the instruction cue disappeared in the immediate-saccade task, or during the instruction period in the delayed-saccade task. The instruction cue offset was the saccade gosignal. Here we focus on 92 task-related neurons: visual, Eye-movement, and instruction/fixation neurons. We found that 73% of SEF Eye-movement–related neurons fired significantly more before anti-saccades than prosaccades. This finding was analyzed at 3 levels: population, single neuron, and individual trial. On individual antisaccade trials, 40 ms before saccade, the firing rate of Eye-movem...
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Primate antisaccade. II. Supplementary Eye Field neuronal activity predicts correct performance.
Journal of Neurophysiology, 2004Co-Authors: Nelly Amador, Madeleine Schlag-rey, John SchlagAbstract:Neuronal activities were recorded in the Supplementary Eye Field (SEF) of 3 macaque monkeys trained to perform antisaccades pseudorandomly interleaved with prosaccades, as instructed by the shape o...
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Reward-predicting and reward-detecting neuronal activity in the primate Supplementary Eye Field.
Journal of Neurophysiology, 2000Co-Authors: Nelly Amador, Madeleine Schlag-rey, John SchlagAbstract:In addition to cells specifically active with visual stimuli, saccades, or fixation, the Supplementary Eye Field contains cells that fire in precise temporal relationship with the occurrence of reward. We studied reward-related activity in two monkeys performing a prosaccade/antisaccade task and in one monkey trained in memory prosaccades only. Two types of neurons were distinguished by their reciprocal firing pattern: reward-predicting (RP) and reward-detecting (RD). RP neurons linearly increased their firing as early as 150 ms before saccade onset until the occurrence of reward, at which time they abruptly ceased firing. In contrast, RD neurons fired in phase with reward delivery, even when its duration was varied and when it was repeated at different frequencies. RD discharges were little affected or unaffected by the position of a visual cue that briefly anchored the goal at the onset of reward. The complementary firing patterns of the RP and RD neurons could provide a feedback mechanism necessary for learning and performing the task.
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antisaccade performance predicted by neuronal activity in the Supplementary Eye Field
Nature, 1997Co-Authors: Madeleine Schlagrey, Nelly Amador, H. Sanchez, John SchlagAbstract:The voluntary control of gaze implies the ability to make saccadic Eye movements specified by abstract instructions, as well as the ability to repress unwanted orientating to sudden stimuli. Both of these abilities are challenged in the antisaccade task, because it requires subjects to look at an unmarked location opposite to a flashed stimulus, without glancing at it1,2. Performance on this task depends on the frontal/prefrontal cortex and related structures3,4,5,6,7,8, but the neuronal operations underlying antisaccades are not understood. It is not known, for example, how excited visual neurons that normally trigger a saccade to a target (a prosaccade) can activate oculomotor neurons directing gaze in the opposite direction. Visual neurons might, perhaps, alter their receptive Fields depending on whether they receive a pro- or antisaccade instruction. If the receptive Field is not altered, the antisaccade goal must be computed and imposed from the top down to the appropriate oculomotor neurons. Here we show, using recordings from the Supplementary Eye Field (a frontal cortex oculomotor centre) in monkeys, that visual and movement neurons retain the same spatial selectivity across randomly mixed pro- and antisaccade trials. However, these neurons consistently fire more before antisaccades than prosaccades with the same trajectories, suggesting a mechanism through which voluntary antisaccade commands can override reflexive glances.
Xiaomo Chen - One of the best experts on this subject based on the ideXlab platform.
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inactivation of medial frontal cortex changes risk preference
Current Biology, 2018Co-Authors: Veit Stuphorn, Xiaomo ChenAbstract:Summary Humans and other animals need to make decisions under varying degrees of uncertainty. These decisions are strongly influenced by an individual’s risk preference; however, the neuronal circuitry by which risk preference shapes choice is still unclear [ 1 ]. Supplementary Eye Field (SEF), an oculomotor area within primate medial frontal cortex, is thought to be an essential part of the neuronal circuit underlying oculomotor decision making, including decisions under risk [ 2 , 3 , 4 , 5 ]. Consistent with this view, risk-related action value and monitoring signals have been observed in SEF [ 6 , 7 , 8 ]. However, such activity has also been observed in other frontal areas, including orbitofrontal [ 9 , 10 , 11 ], cingulate [ 12 , 13 , 14 ], and dorsal-lateral frontal cortex [ 15 ]. It is thus unknown whether the activity in SEF causally contributes to risky decisions, or whether it is merely a reflection of neural processes in other cortical regions. Here, we tested a causal role of SEF in risky oculomotor choices. We found that SEF inactivation strongly reduced the frequency of risky choices. This reduction was largely due to a reduced attraction to reward uncertainty and high reward gain, but not due to changes in the subjective estimation of reward probability or average expected reward. Moreover, SEF inactivation also led to increased sensitivity to differences between expected and actual reward during free choice. Nevertheless, it did not affect adjustments of decisions based on reward history.
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inactivation of medial frontal cortex changes risk preference
bioRxiv, 2018Co-Authors: Veit Stuphorn, Xiaomo ChenAbstract:Summary Humans and other animals need to make decisions under varying degrees of uncertainty. These decisions are strongly influenced by an individual’s risk preference, however the neuronal circuitry by which risk preference shapes choice is still unclear [1]. Supplementary Eye Field (SEF), an oculomotor area within primate medial frontal cortex, is thought to be an essential part of the neuronal circuit underlying oculomotor decision-making, including decisions under risk [2–5]. Consistent with this view, risk-related action value and monitoring signals have been observed in SEF [6–8]. However, such activity has also been observed in other frontal areas, including orbitofrontal [9–11], cingulate [12–14], and dorsal lateral frontal cortex [15]. It is thus unknown whether the activity in SEF causally contributes to risky decisions, or if it is merely a reflection of neural processes in other cortical regions. Here, we tested a causal role of SEF in risky oculomotor choices. We found that SEF inactivation strongly reduced the frequency of risky choices. This reduction was largely due to a reduced attraction to reward uncertainty and high reward gain, but not due to changes in the subjective estimation of reward probability or average expected reward. Moreover, SEF inactivation also led to increased sensitivity to differences between expected and actual reward during free choice. Nevertheless, it did not affect adjustments of decisions based on reward history.
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Sequential selection of economic good and action in medial frontal cortex of macaques during value-based decisions
eLife, 2015Co-Authors: Xiaomo Chen, Veit StuphornAbstract:Value-based decisions could rely either on the selection of desired economic goods or on the selection of the actions that will obtain the goods. We investigated this question by recording from the Supplementary Eye Field (SEF) of monkeys during a gambling task that allowed us to distinguish chosen good from chosen action signals. Analysis of the individual neuron activity, as well as of the population state-space dynamic, showed that SEF encodes first the chosen gamble option (the desired economic good) and only ~100 ms later the saccade that will obtain it (the chosen action). The action selection is likely driven by inhibitory interactions between different SEF neurons. Our results suggest that during value-based decisions, the selection of economic goods precedes and guides the selection of actions. The two selection steps serve different functions and can therefore not compensate for each other, even when information guiding both processes is given simultaneously.
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sequential selection of economic good and action in medial frontal cortex of macaques during value based decisions
eLife, 2015Co-Authors: Xiaomo Chen, Veit StuphornAbstract:Much of our decision making seems to involve selecting the best option from among those currently available, and then working out how to attain that particular outcome. However, while this might sound straightforward in principle, exactly how this process is organized within the brain is not entirely clear. One possibility is that the brain compares all the possible outcomes of a decision with each other before constructing a plan of action to achieve the most desirable of these. This is known as the 'goods-based' model of decision making. However, an alternative possibility is that the brain instead considers all the possible actions that could be performed at any given time. One specific action is then chosen based on a range of factors, including the potential outcomes that might result from each. This is an 'action-based' model of decision making. Chen and Stuphorn have now distinguished between these possibilities by training two monkeys to perform a gambling task. The animals learned to make Eye movements to one of two targets on a screen to earn a reward. The identity of the targets varied between trials, with some associated with larger rewards or a higher likelihood of receiving a reward than others. The location of the targets also changed in different trials, which meant that the choice of 'action' (moving the Eyes to the left or right) could be distinguished from the choice of 'goods' (the reward). By using electrodes to record from a region of the brain called the Supplementary Eye Field, which helps to control Eye movements, Chen and Stuphorn showed that the activity of neurons in this region predicted the monkeys’ decision-making behavior. Crucially, it did so in two stages: neurons first encoded the reward chosen by the monkey, before subsequently encoding the action that the monkey selected to obtain that outcome. These data argue against an action-based model of decision making because outcomes are encoded before actions. However, they also argue against a purely goods-based model. This is because all possible actions are encoded by the brain (including those that are subsequently rejected), with the highest levels of activity seen for the action that is ultimately selected. The data instead support a new model of decision making, in which outcomes and actions are selected sequentially via two independent brain circuits.
Mickael Tanter - One of the best experts on this subject based on the ideXlab platform.
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Functional ultrasound imaging of the brain reveals propagation of task-related brain activity in behaving primates
Nature Communications, 2019Co-Authors: Alexandre Dizeux, Pierre Pouget, Marc Gesnik, Thomas Deffieux, Harry Ahnine, Kevin Blaize, Fabrice Arcizet, Serge Picaud, José-alain Sahel, Mickael TanterAbstract:Neuroimaging modalities such as MRI and EEG are able to record from the whole brain, but this comes at the price of either limited spatiotemporal resolution or limited sensitivity. Here, we show that functional ultrasound imaging (fUS) of the brain is able to assess local changes in cerebral blood volume during cognitive tasks, with sufficient temporal resolution to measure the directional propagation of signals. In two macaques, we observed an abrupt transient change in Supplementary Eye Field (SEF) activity when animals were required to modify their behaviour associated with a change of saccade tasks. SEF activation could be observed in a single trial, without averaging. Simultaneous imaging of anterior cingulate cortex and SEF revealed a time delay in the directional functional connectivity of 0.27 ± 0.07 s and 0.9 ± 0.2 s for both animals. Cerebral hemodynamics of large brain areas can be measured at high spatiotemporal resolution using fUS.
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transcranial ultrasonic stimulation modulates single neuron discharge in macaques performing an antisaccade task
Brain Stimulation, 2017Co-Authors: Nicolas Wattiez, Thomas Deffieux, Mickael Tanter, Charlotte Constans, Pierre M Daye, Jeanfrancois Aubry, Pierre PougetAbstract:Background: Low intensity transcranial ultrasonic stimulation (TUS) has been demonstrated to non-invasively and transiently stimulate the nervous system. Although US neuromodulation has appeared robust in rodent studies, the effects of US in large mammals and humans have been modest at best. In addition, there is a lack of direct recordings from the stimulated neurons in response to US. Our study investigates the magnitude of the US effects on neuronal discharge in awake behaving monkeys and thus fills the void on both fronts. Objective/Hypothesis: In this study, we demonstrate the feasibility of recording action potentials in the Supplementary Eye Field (SEF) as TUS is applied simultaneously to the frontal Eye Field (FEF) in macaques performing an antisaccade task. Results: We show that compared to a control stimulation in the visual cortex, SEF activity is significantly modulated shortly after TUS onset. Among all cell types 40% of neurons significantly changed their activity after TUS. Half of the neurons showed a transient increase of activity induced by TUS. Conclusion: Our study demonstrates that the neuromodulatory effects of non-invasive focused ultrasound can be assessed in real time in awake behaving monkeys by recording discharge activity from a brain region reciprocally connected with the stimulated region. The study opens the door for further parametric studies for fine-tuning the ultrasonic parameters. The ultrasonic effect could indeed be quantified based on the direct measurement of the intensity of the modulation induced on a single neuron in a freely performing animal. The technique should be readily reproducible in other primate laboratories studying brain function, both for exploratory and therapeutic purposes and to facilitate the development of future clinical TUS devices.
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Functional ultrasound imaging in awake non-human primates performing voluntary saccade
2017 IEEE International Ultrasonics Symposium (IUS), 2017Co-Authors: Alexandre Dizeux, Pierre Pouget, Nicolas Wattiez, Marc Gesnik, Thomas Deffieux, Mickael TanterAbstract:Functional ultrasound (fUS) is a novel technique for in vivo neuroimaging which allows to map subtle changes of the Cerebral Blood Volume (CBV) due to neurovascular coupling with a very high sensitivity, and thus map dynamics of brain activity [1]. In this study, we apply fUS to awake and behaving non-human primate to investigate the monitoring of saccadic Eye movement by the Supplementary Eye Field (SEF) brain region [2]. This represents the first fUS images in non-human primate, doing complex tasks, which generally remains very challenging to perform in an MRI environment in awake and behaving conditions.