Skip to main content

Amos Arieli

Follower

1

Following

2

Co-author

1

Public Views

Researcher in the Department of Brain Sciences, The Weizmann Inst. of Science, head of the Active Sensing Laboratory. I investigate conscious perception as an emerging property of action-perception coupling and brain mechanisms of visual perception and motor action.

less

Ferdinando Mussa-ivaldi

Francesco Iberite

Ecole Polytechnique Federale de Lausanne

דויד סון

Richard Kronland-Martinet

Centre National de la Recherche Scientifique / French National Centre for Scientific Research

Interests

Uploads

Papers by Amos Arieli

Idiosyncratic selection of active touch for shape perception

Scientific Reports, 2022

Hand movements are essential for tactile perception of objects. However, the specific functions s... more Hand movements are essential for tactile perception of objects. However, the specific functions served by active touch strategies, and their dependence on physiological parameters, are unclear and understudied. Focusing on planar shape perception, we tracked at high resolution the hands of 11 participants during shape recognition task. Two dominant hand movement strategies were identified: contour following and scanning. Contour following movements were either tangential to the contour or oscillating perpendicular to it. Scanning movements crossed between distant parts of the shapes’ contour. Both strategies exhibited non-uniform coverage of the shapes’ contours. Idiosyncratic movement patterns were specific to the sensed object. In a second experiment, we have measured the participants’ spatial and temporal tactile thresholds. Significant portions of the variations in hand speed and in oscillation patterns could be explained by the idiosyncratic thresholds. Using data-driven simula...

Fairness Motivations and Procedures of Choice between Lotteries as Revealed through Eye Movements

Eye tracking is used to investigate decision makers' motivations and procedures in choice pro... more Eye tracking is used to investigate decision makers' motivations and procedures in choice problems. Patterns of eye movements in problems where the deliberation process is easily discernable are used to understand the deliberation in other problems. We find that in problems which involve the distribution of income between the participant and another individual, participants who behave selfishly nevertheless take into consideration the size of the payment to the other person. In problems that involve choice between two simple lotteries, eye movements indicate that many participants based their decision on a comparison of prizes and probabilities rather than making an expected utility calculation.

Cortical Dynamics in Behaving Monkeys Long-Term Voltage-Sensitive Dye Imaging Reveals

A novel method of chronic optical imaging based on new voltage-sensitive dyes (VSDs) was develope... more A novel method of chronic optical imaging based on new voltage-sensitive dyes (VSDs) was developed to facilitate the explorations of the spatial and temporal patterns underlying higher cognitive functions in the neocortex of behaving monkeys. Using this system, we were able to explore cortical dynamics, with high spatial and temporal resolution, over period of Յ1 yr from the same patch of cortex. The visual cortices of trained macaques were stained one to three times a week, and immediately after each staining session, the monkey started to perform the behavioral task, while the primary and secondary visual areas (V1 and V2) were imaged with a fast optical imaging system. Long-term repeated VSD imaging (VSDI) from the same cortical area did not disrupt the normal cortical architecture as confirmed repeatedly by optical imaging based on intrinsic signals. The spatial patterns of functional maps obtained by VSDI were essentially identical to those obtained from the same patch of cortex by imaging based on intrinsic signals. On comparing the relative amplitudes of the evoked signals and differential map obtained using these two different imaging methodologies, we found that VSDI emphasizes subthreshold activity more than imaging based on intrinsic signals, that emphasized more spiking activity. The latency of the VSD-evoked response in V1 ranged from 46 to 68 ms in the different monkeys. The amplitude of the V2 response was only 20Ϫ60% of that in V1. As expected from the anatomy, the retinotopic responses to local visual stimuli spread laterally across the cortical surface at a spreading velocity of 0.15Ϫ0.19 m/s over a larger area than that expected by the classical magnification factor, reaching its maximal anisotropic spatial extent within ϳ40 ms. We correlated the observed dynamics of cortical activation patterns with the monkey's saccadic eye movements and found that due to the slow offset of the cortical response relative to its onset, there was a short period of simultaneous activation of two distinct patches of cortex following a saccade to the visual stimulus. We also found that a saccade to a small stimulus was followed by direct transient activation of a cortical region in areas of V1 and V2, located retinotopically within the saccadic trajectory.

Active palpation underlying shape perception is shaped by physiological thresholds and experience

ABSTRACTHand movements are essential for tactile perception of objects. However, why different in... more ABSTRACTHand movements are essential for tactile perception of objects. However, why different individuals converge on specific movement patterns is not yet clear. Focusing on planar shape perception, we tracked the hands of 11 participants while they practiced shape recognition. Our results show that planar shape perception is mediated by contour-following movements, either tangential to the contour or spatially-oscillating perpendicular to it, and by scanning movements, crossing between distant parts of the shapes’ contour. Both strategies exhibited non-uniform coverage of the shapes’ contours. We found that choice of strategy during the first experimental session was strongly correlated with two idiosyncratic parameters: participants with lower tactile resolution tended to move faster; and faster-adapting participants tended to employ oscillatory movements more often. In addition, practicing on isolated geometric features increased the tendency to use the contour-following strate...

Active Sensory Substitution Allows Fast Learning Via Effective Motor-Sensory Strategies

SSRN Electronic Journal, 2020

We examined the development of new sensing abilities in adults by training participants to percei... more We examined the development of new sensing abilities in adults by training participants to perceive remote objects through their fingers. Using an Active-Sensing based sensory Substitution device (ASenSub), participants quickly learned to perceive fast via the new modality and preserved their high performance for more than 20 months. Both sighted and blind participants exhibited almost complete transfer of performance from 2D images to novel 3D physical objects. Perceptual accuracy and speed using the ASenSub were, on average, 300% and 600% better than previous reports for 2D images and 3D objects. This improvement is attributed to the ability of the participants to employ their own motor-sensory strategies. Sighted participants dominant strategy was based on motor-sensory convergence on the most informative regions of objects, similarly to fixation patterns in vision. Congenitally, blind participants did not show such a tendency, and many of their exploratory procedures resembled those observed with natural touch.

Studying the precuneus reveals structure-function-affect correlation in long-term meditators

Understanding the relationship between brain structure, function and self-reports has hardly been... more Understanding the relationship between brain structure, function and self-reports has hardly been addressed until now in meditation research. Here we demonstrate such relationship, using Mindfulness meditation (MM). MM aims to reduce thought-related processes and enhance bodily awareness, thereby reducing identification with thought content and deconstructing maladaptive self-schema. We thus hypothesized that structure of the default mode network (DMN) regions, associated with spontaneous thoughts and self-representation, would negatively correlate with MM experience and self-reported positive affect, while positively correlating with DMN resting-state function.Cross-sectionally comparing a unique group of adept MM practitioners and meditation-naïve matched controls using voxel based morphometry revealed that gray matter (GM) density of the left precuneus (L-Prc) was negatively correlated with MM expertise. Furthermore, GM density of the L-Prc was positively correlated with resting ...

Inter-thinker consistency of language activations during abstract thoughts

Human brain imaging typically employs structured and controlled tasks to avoid variable and incon... more Human brain imaging typically employs structured and controlled tasks to avoid variable and inconsistent activation patterns. Here we argue against this assumption by showing that an extremely open-ended, high level cognitive task-loosely defined as “abstract thinking” leads to a precise, and highly consistent activation maps. Thus we show that activation maps generated during such cognitive process were precisely located relative to borders of well-known networks such as internal speech, visual and motor imagery. The activation patterns allowed decoding the thought condition at >95%. Surprisingly, the activated networks remained the same regardless of changes in thought content. Finally, we found a remarkably consistent activation map across individuals engaged in abstract thinking. The activation to abstract thinking bordered, but strictly avoided visual and motor networks. On the other hand, it partly overlapped with left lateralized language networks. These observations were ...

Long-Term Optical Imaging and Spectroscopy Reveal Mechanisms Underlying the Intrinsic Signal and Stability of Cortical Maps in V1 of Behaving Monkeys

The Journal of Neuroscience, 2000

Explorations of learning and memory, other long-term plastic changes, and additional cognitive fu... more Explorations of learning and memory, other long-term plastic changes, and additional cognitive functions in the behaving primate brain would greatly benefit from the ability to image the functional architecture within the same patch of cortex, at the columnar level, for a long period of time. We developed methods for long-term optical imaging based on intrinsic signals and repeatedly visualized the same functional domains in behaving macaque cortex for a period extending over 1 year. Using optical imaging and imaging spectroscopy, we first explored the relationship between electrical activity and hemodynamic events in the awake behaving primate and compared it with anesthetized preparations. We found that, whereas the amplitude of the intrinsic signal was much larger in the awake animal, its temporal pattern was similar to that observed in the anesthetized animals. In both groups, deoxyhemoglobin concentration reached a peak 2–3 sec after stimulus onset. Furthermore, the early activ...

Fundamental Investigations of Superplastic Forming Processes

IS. SECURITY CLASS. (of chi* #eport) Unclassified DS. OECLASSIFICATION OOWNGRAOING SCHEDULE 16. D... more IS. SECURITY CLASS. (of chi* #eport) Unclassified DS. OECLASSIFICATION OOWNGRAOING SCHEDULE 16. DISTRIBUTION STATEMENT (of Ii$ Reporte ). Aroafor publ 10O se 1 distributionl unliLmite04. 17. 01ISTRIS16U TION STA TE6MENasT (of the abt,.uf .ntpodiAn Block 20, HI di Iferen t from. Report) f-E T Is. SUPPLEMtNTARY NOTES F To be published in part in Acta Metalturgica C) It KEY WORDS (Continue on reves, side it neressry and udenrit)b.y blnck nunmber) LL! Supcrplasticity, mechanical behavior, deformation mechanisms, three-dimensional _j deformation mechanism map " 1 i 4 ~ A S S . T I C U r n o n r e, r e a i d e I t n e cg ., a r y .a n d I d e i r y h y 6 l , n b ~ r jTe eeva ed dvior of Zn-A! alloy was investigated, with :,. special emphasis on the micromechanisms of" deformation. Constant strain rate data on f1ow stress vs strain rate at different temperature and with speimens with different grain sizes were analyzed. From this anaysis the constitutive equations for superplastiC creep, dislooation-climb creep, ooble creep and Nabarro creep processes were established. Finally the results were depited in the form of a three-dimensional deformation mechanism map with normalised parameters of grain size, temperature and stress as the coordinates. Unclassified SECURITY CLASSIFICATION OR THIS P&GE ,itWhen I'altie F ntf tl.

Data for default network reduced functional connectivity in meditators, negatively correlated with meditation expertise

Data in Brief, 2016

FMRI data described here was recorded during resting-state in Mindfulness Meditators (MM) and con... more FMRI data described here was recorded during resting-state in Mindfulness Meditators (MM) and control participants (see "Taskinduced activity and resting-state fluctuations undergo similar alterations in visual and DMN areas of long-term meditators" [1] for details). MM participants were also scanned during meditation. Analyses focused on functional connectivity within and between the default mode network (DMN) and visual network (Vis). Here we show data demonstrating that: 1) Functional connectivity within the DMN and the Visual networks were higher in the control group than in the meditators; 2) Data show an increase for the functional connectivity between the DMN and the Visual networks in the meditators compared to controls; 3) Data demonstrate that functional connectivity both within and between networks reduces during meditation, compared to the resting-state; and 4) A significant negative correlation was found between DMN functional connectivity and meditation expertise. The reader is referred to [1] for further interpretation and discussion.

Microsaccades and drift are similarly modulated by stimulus contrast and anticipation

Journal of Vision, 2014

Abstracts of the 16th Annual Meeting of The Israel Society for Neuroscience: Eilat, Israel, November 25–27, 2007

Neural Plasticity, 2007

The Israel Society for Neuroscience—ISFN—was founded in 1993 by a group of Israeli leading scient... more The Israel Society for Neuroscience—ISFN—was founded in 1993 by a group of Israeli leading scientists conducting research in the area of neurobiology. The primary goal of the society was to promote and disseminate the knowledge and understanding acquired by its members, and to strengthen interactions between them. Since then, the society holds its annual meeting every year in Eilat usually during December. At this annual meetings, the senior Israeli neurobiologists, their teams, and their graduate students, as well as foreign scientists and students, present their recent research findings in platform and poster presentations, and the program of the meeting is mainly based on the 338 received abstracts which are published in this volume. The meeting also offers the opportunity for the researchers to exchange information with each other, often leading to the initiation of collaborative studies. Both the number of members of the society and those participating in the annual meeting is ...

In-vivo Optical Imaging of Cortical Architecture and Dynamics

Modern Techniques in Neuroscience Research, 1999

Motor-Sensory Confluence in Tactile Perception

The Journal of Neuroscience, 2012

Perception involves motor control of sensory organs. However, the dynamics underlying emergence o... more Perception involves motor control of sensory organs. However, the dynamics underlying emergence of perception from motor-sensory interactions are not yet known. Two extreme possibilities are as follows: (1) motor and sensory signals interact within an open-loop scheme in which motor signals determine sensory sampling but are not affected by sensory processing and (2) motor and sensory signals are affected by each other within a closed-loop scheme. We studied the scheme of motor-sensory interactions in humans using a novel object localization task that enabled monitoring the relevant overt motor and sensory variables. We found that motor variables were dynamically controlled within each perceptual trial, such that they gradually converged to steady values. Training on this task resulted in improvement in perceptual acuity, which was achieved solely by changes in motor variables, without any change in the acuity of sensory readout. The within-trial dynamics is captured by a hierarchic...

Layer-Specific Touch-Dependent Facilitation and Depression in the Somatosensory Cortex during Active Whisking

The Journal of Neuroscience, 2006

Brains adapt to new situations by retuning their neurons. The most common form of neuronal adapta... more Brains adapt to new situations by retuning their neurons. The most common form of neuronal adaptation, typically observed with repetitive stimulations of passive sensory organs, is depression (responses gradually decrease until stabilized). We studied cortical adaptation when stimuli are acquired by active movements of the sensory organ. In anesthetized rats, artificial whisking was induced at 5 Hz, and activity of individual neurons in layers 2–5 was recorded during whisking in air (Whisking condition) and whisking against an object (Touch condition). Response strengths were assessed by spike counts. Input-layer responses (layers 4 and 5a) usually facilitated during the whisking train, whereas superficial responses (layer 2/3) usually depressed. In layers 2/3 and 4, but not 5a, responses were usually stronger during touch trials than during whisking in air. Facilitations were specific to the protraction phase; during retraction, responses depressed in all layers and conditions. The...

Dependence of Cortical Plasticity on Correlated Activity of Single Neurons and on Behavioral Context

Science, 1992

Dynamics of Depolarization and Hyperpolarization in the Frontal Cortex and Saccade Goal

Science, 2002

The frontal eye field and neighboring area 8Ar of the primate cortex are involved in programming ... more The frontal eye field and neighboring area 8Ar of the primate cortex are involved in programming and execution of saccades. Electrical microstimulation in these regions elicits short-latency contralateral saccades. To determine how spatiotemporal dynamics of microstimulation-evoked activity are converted into saccade plans, we used a combination of real-time optical imaging and microstimulation in behaving monkeys. Short stimulation trains evoked a rapid and widespread wave of depolarization followed by unexpected large and prolonged hyperpolarization. During this hyperpolarization saccades are almost exclusively ipsilateral, suggesting an important role for hyperpolarization in determining saccade goal.

Linking Spontaneous Activity of Single Cortical Neurons and the Underlying Functional Architecture

Science, 1999

The relation between the activity of a single neocortical neuron and the dynamics of the network ... more The relation between the activity of a single neocortical neuron and the dynamics of the network in which it is embedded was explored by single-unit recordings and real-time optical imaging. The firing rate of a spontaneously active single neuron strongly depends on the instantaneous spatial pattern of ongoing population activity in a large cortical area. Very similar spatial patterns of population activity were observed both when the neuron fired spontaneously and when it was driven by its optimal stimulus. The evoked patterns could be used to reconstruct the spontaneous activity of single neurons.

Never Resting Brain: Simultaneous Representation of Two Alpha Related Processes in Humans

PLoS ONE, 2008

Brain activity is continuously modulated, even at ''rest''. The alpha rhythm (8-12 Hz) has been k... more Brain activity is continuously modulated, even at ''rest''. The alpha rhythm (8-12 Hz) has been known as the hallmark of the brain's idle-state. However, it is still debated if the alpha rhythm reflects synchronization in a distributed network or focal generator and whether it occurs spontaneously or is driven by a stimulus. This EEG/fMRI study aimed to explore the source of alpha modulations and their distribution in the resting brain. By serendipity, while computing the individually defined power modulations of the alpha-band, two simultaneously occurring components of these modulations were found. An 'induced alpha' that was correlated with the paradigm (eyes open/ eyes closed), and a 'spontaneous alpha' that was ongoing and unrelated to the paradigm. These alpha components when used as regressors for BOLD activation revealed two segregated activation maps: the 'induced map' included left lateral temporal cortical regions and the hippocampus; the 'spontaneous map' included prefrontal cortical regions and the thalamus. Our combined fMRI/EEG approach allowed to computationally untangle two parallel patterns of alpha modulations and underpin their anatomical basis in the human brain. These findings suggest that the human alpha rhythm represents at least two simultaneously occurring processes which characterize the 'resting brain'; one is related to expected change in sensory information, while the other is endogenous and independent of stimulus change.

Interhemispheric correlations of slow spontaneous neuronal fluctuations revealed in human sensory cortex

Nature Neuroscience, 2008

Animal studies have shown robust electrophysiological activity in the sensory cortex in the absen... more Animal studies have shown robust electrophysiological activity in the sensory cortex in the absence of stimuli or tasks. Similarly, recent human functional magnetic resonance imaging (fMRI) revealed widespread, spontaneously emerging cortical fluctuations. However, it is unknown what neuronal dynamics underlie this spontaneous activity in the human brain. Here we studied this issue by combining bilateral single-unit, local field potentials (LFPs) and intracranial electrocorticography (ECoG) recordings in individuals undergoing clinical monitoring. We found slow (<0.1 Hz, following 1/f-like profiles) spontaneous fluctuations of neuronal activity with significant interhemispheric correlations. These fluctuations were evident mainly in neuronal firing rates and in gamma (40-100 Hz) LFP power modulations. Notably, the interhemispheric correlations were enhanced during rapid eye movement and stage 2 sleep. Multiple intracranial ECoG recordings revealed clear selectivity for functional networks in the spontaneous gamma LFP power modulations. Our results point to slow spontaneous modulations in firing rate and gamma LFP as the likely correlates of spontaneous fMRI fluctuations in the human sensory cortex. The neuronal events occurring in the sensory cortex when no stimulus is presented are not well understood. Contrary to traditional feed-forward models of information processing, a growing body of single-unit, LFP, electroencephalography (EEG), and optical imaging data point to robust levels of spontaneous neuronal activity in sensory areas of the mammalian cortex 1-7 . The modulation of such spontaneous neuronal activity can occur on very slow time scales 8, 9 . These robust spontaneous waves pose a challenge for models linking neuronal activity and sensory perception 10,11 , namely in explaining how the brain distinguishes between spontaneous events and vivid sensory percepts. One possibility is that the precise neuronal dynamics differ substantially between spontaneous and sensory-evoked conditions. This

Idiosyncratic selection of active touch for shape perception

Scientific Reports, 2022

Hand movements are essential for tactile perception of objects. However, the specific functions s... more Hand movements are essential for tactile perception of objects. However, the specific functions served by active touch strategies, and their dependence on physiological parameters, are unclear and understudied. Focusing on planar shape perception, we tracked at high resolution the hands of 11 participants during shape recognition task. Two dominant hand movement strategies were identified: contour following and scanning. Contour following movements were either tangential to the contour or oscillating perpendicular to it. Scanning movements crossed between distant parts of the shapes’ contour. Both strategies exhibited non-uniform coverage of the shapes’ contours. Idiosyncratic movement patterns were specific to the sensed object. In a second experiment, we have measured the participants’ spatial and temporal tactile thresholds. Significant portions of the variations in hand speed and in oscillation patterns could be explained by the idiosyncratic thresholds. Using data-driven simula...

Fairness Motivations and Procedures of Choice between Lotteries as Revealed through Eye Movements

Eye tracking is used to investigate decision makers' motivations and procedures in choice pro... more Eye tracking is used to investigate decision makers' motivations and procedures in choice problems. Patterns of eye movements in problems where the deliberation process is easily discernable are used to understand the deliberation in other problems. We find that in problems which involve the distribution of income between the participant and another individual, participants who behave selfishly nevertheless take into consideration the size of the payment to the other person. In problems that involve choice between two simple lotteries, eye movements indicate that many participants based their decision on a comparison of prizes and probabilities rather than making an expected utility calculation.

Cortical Dynamics in Behaving Monkeys Long-Term Voltage-Sensitive Dye Imaging Reveals

A novel method of chronic optical imaging based on new voltage-sensitive dyes (VSDs) was develope... more A novel method of chronic optical imaging based on new voltage-sensitive dyes (VSDs) was developed to facilitate the explorations of the spatial and temporal patterns underlying higher cognitive functions in the neocortex of behaving monkeys. Using this system, we were able to explore cortical dynamics, with high spatial and temporal resolution, over period of Յ1 yr from the same patch of cortex. The visual cortices of trained macaques were stained one to three times a week, and immediately after each staining session, the monkey started to perform the behavioral task, while the primary and secondary visual areas (V1 and V2) were imaged with a fast optical imaging system. Long-term repeated VSD imaging (VSDI) from the same cortical area did not disrupt the normal cortical architecture as confirmed repeatedly by optical imaging based on intrinsic signals. The spatial patterns of functional maps obtained by VSDI were essentially identical to those obtained from the same patch of cortex by imaging based on intrinsic signals. On comparing the relative amplitudes of the evoked signals and differential map obtained using these two different imaging methodologies, we found that VSDI emphasizes subthreshold activity more than imaging based on intrinsic signals, that emphasized more spiking activity. The latency of the VSD-evoked response in V1 ranged from 46 to 68 ms in the different monkeys. The amplitude of the V2 response was only 20Ϫ60% of that in V1. As expected from the anatomy, the retinotopic responses to local visual stimuli spread laterally across the cortical surface at a spreading velocity of 0.15Ϫ0.19 m/s over a larger area than that expected by the classical magnification factor, reaching its maximal anisotropic spatial extent within ϳ40 ms. We correlated the observed dynamics of cortical activation patterns with the monkey's saccadic eye movements and found that due to the slow offset of the cortical response relative to its onset, there was a short period of simultaneous activation of two distinct patches of cortex following a saccade to the visual stimulus. We also found that a saccade to a small stimulus was followed by direct transient activation of a cortical region in areas of V1 and V2, located retinotopically within the saccadic trajectory.

Active palpation underlying shape perception is shaped by physiological thresholds and experience

ABSTRACTHand movements are essential for tactile perception of objects. However, why different in... more ABSTRACTHand movements are essential for tactile perception of objects. However, why different individuals converge on specific movement patterns is not yet clear. Focusing on planar shape perception, we tracked the hands of 11 participants while they practiced shape recognition. Our results show that planar shape perception is mediated by contour-following movements, either tangential to the contour or spatially-oscillating perpendicular to it, and by scanning movements, crossing between distant parts of the shapes’ contour. Both strategies exhibited non-uniform coverage of the shapes’ contours. We found that choice of strategy during the first experimental session was strongly correlated with two idiosyncratic parameters: participants with lower tactile resolution tended to move faster; and faster-adapting participants tended to employ oscillatory movements more often. In addition, practicing on isolated geometric features increased the tendency to use the contour-following strate...

Active Sensory Substitution Allows Fast Learning Via Effective Motor-Sensory Strategies

SSRN Electronic Journal, 2020

We examined the development of new sensing abilities in adults by training participants to percei... more We examined the development of new sensing abilities in adults by training participants to perceive remote objects through their fingers. Using an Active-Sensing based sensory Substitution device (ASenSub), participants quickly learned to perceive fast via the new modality and preserved their high performance for more than 20 months. Both sighted and blind participants exhibited almost complete transfer of performance from 2D images to novel 3D physical objects. Perceptual accuracy and speed using the ASenSub were, on average, 300% and 600% better than previous reports for 2D images and 3D objects. This improvement is attributed to the ability of the participants to employ their own motor-sensory strategies. Sighted participants dominant strategy was based on motor-sensory convergence on the most informative regions of objects, similarly to fixation patterns in vision. Congenitally, blind participants did not show such a tendency, and many of their exploratory procedures resembled those observed with natural touch.

Studying the precuneus reveals structure-function-affect correlation in long-term meditators

Understanding the relationship between brain structure, function and self-reports has hardly been... more Understanding the relationship between brain structure, function and self-reports has hardly been addressed until now in meditation research. Here we demonstrate such relationship, using Mindfulness meditation (MM). MM aims to reduce thought-related processes and enhance bodily awareness, thereby reducing identification with thought content and deconstructing maladaptive self-schema. We thus hypothesized that structure of the default mode network (DMN) regions, associated with spontaneous thoughts and self-representation, would negatively correlate with MM experience and self-reported positive affect, while positively correlating with DMN resting-state function.Cross-sectionally comparing a unique group of adept MM practitioners and meditation-naïve matched controls using voxel based morphometry revealed that gray matter (GM) density of the left precuneus (L-Prc) was negatively correlated with MM expertise. Furthermore, GM density of the L-Prc was positively correlated with resting ...

Inter-thinker consistency of language activations during abstract thoughts

Human brain imaging typically employs structured and controlled tasks to avoid variable and incon... more Human brain imaging typically employs structured and controlled tasks to avoid variable and inconsistent activation patterns. Here we argue against this assumption by showing that an extremely open-ended, high level cognitive task-loosely defined as “abstract thinking” leads to a precise, and highly consistent activation maps. Thus we show that activation maps generated during such cognitive process were precisely located relative to borders of well-known networks such as internal speech, visual and motor imagery. The activation patterns allowed decoding the thought condition at >95%. Surprisingly, the activated networks remained the same regardless of changes in thought content. Finally, we found a remarkably consistent activation map across individuals engaged in abstract thinking. The activation to abstract thinking bordered, but strictly avoided visual and motor networks. On the other hand, it partly overlapped with left lateralized language networks. These observations were ...

Long-Term Optical Imaging and Spectroscopy Reveal Mechanisms Underlying the Intrinsic Signal and Stability of Cortical Maps in V1 of Behaving Monkeys

The Journal of Neuroscience, 2000

Explorations of learning and memory, other long-term plastic changes, and additional cognitive fu... more Explorations of learning and memory, other long-term plastic changes, and additional cognitive functions in the behaving primate brain would greatly benefit from the ability to image the functional architecture within the same patch of cortex, at the columnar level, for a long period of time. We developed methods for long-term optical imaging based on intrinsic signals and repeatedly visualized the same functional domains in behaving macaque cortex for a period extending over 1 year. Using optical imaging and imaging spectroscopy, we first explored the relationship between electrical activity and hemodynamic events in the awake behaving primate and compared it with anesthetized preparations. We found that, whereas the amplitude of the intrinsic signal was much larger in the awake animal, its temporal pattern was similar to that observed in the anesthetized animals. In both groups, deoxyhemoglobin concentration reached a peak 2–3 sec after stimulus onset. Furthermore, the early activ...

Fundamental Investigations of Superplastic Forming Processes

IS. SECURITY CLASS. (of chi* #eport) Unclassified DS. OECLASSIFICATION OOWNGRAOING SCHEDULE 16. D... more IS. SECURITY CLASS. (of chi* #eport) Unclassified DS. OECLASSIFICATION OOWNGRAOING SCHEDULE 16. DISTRIBUTION STATEMENT (of Ii$ Reporte ). Aroafor publ 10O se 1 distributionl unliLmite04. 17. 01ISTRIS16U TION STA TE6MENasT (of the abt,.uf .ntpodiAn Block 20, HI di Iferen t from. Report) f-E T Is. SUPPLEMtNTARY NOTES F To be published in part in Acta Metalturgica C) It KEY WORDS (Continue on reves, side it neressry and udenrit)b.y blnck nunmber) LL! Supcrplasticity, mechanical behavior, deformation mechanisms, three-dimensional _j deformation mechanism map " 1 i 4 ~ A S S . T I C U r n o n r e, r e a i d e I t n e cg ., a r y .a n d I d e i r y h y 6 l , n b ~ r jTe eeva ed dvior of Zn-A! alloy was investigated, with :,. special emphasis on the micromechanisms of" deformation. Constant strain rate data on f1ow stress vs strain rate at different temperature and with speimens with different grain sizes were analyzed. From this anaysis the constitutive equations for superplastiC creep, dislooation-climb creep, ooble creep and Nabarro creep processes were established. Finally the results were depited in the form of a three-dimensional deformation mechanism map with normalised parameters of grain size, temperature and stress as the coordinates. Unclassified SECURITY CLASSIFICATION OR THIS P&GE ,itWhen I'altie F ntf tl.

Data for default network reduced functional connectivity in meditators, negatively correlated with meditation expertise

Data in Brief, 2016

FMRI data described here was recorded during resting-state in Mindfulness Meditators (MM) and con... more FMRI data described here was recorded during resting-state in Mindfulness Meditators (MM) and control participants (see "Taskinduced activity and resting-state fluctuations undergo similar alterations in visual and DMN areas of long-term meditators" [1] for details). MM participants were also scanned during meditation. Analyses focused on functional connectivity within and between the default mode network (DMN) and visual network (Vis). Here we show data demonstrating that: 1) Functional connectivity within the DMN and the Visual networks were higher in the control group than in the meditators; 2) Data show an increase for the functional connectivity between the DMN and the Visual networks in the meditators compared to controls; 3) Data demonstrate that functional connectivity both within and between networks reduces during meditation, compared to the resting-state; and 4) A significant negative correlation was found between DMN functional connectivity and meditation expertise. The reader is referred to [1] for further interpretation and discussion.

Microsaccades and drift are similarly modulated by stimulus contrast and anticipation

Journal of Vision, 2014

Abstracts of the 16th Annual Meeting of The Israel Society for Neuroscience: Eilat, Israel, November 25–27, 2007

Neural Plasticity, 2007

The Israel Society for Neuroscience—ISFN—was founded in 1993 by a group of Israeli leading scient... more The Israel Society for Neuroscience—ISFN—was founded in 1993 by a group of Israeli leading scientists conducting research in the area of neurobiology. The primary goal of the society was to promote and disseminate the knowledge and understanding acquired by its members, and to strengthen interactions between them. Since then, the society holds its annual meeting every year in Eilat usually during December. At this annual meetings, the senior Israeli neurobiologists, their teams, and their graduate students, as well as foreign scientists and students, present their recent research findings in platform and poster presentations, and the program of the meeting is mainly based on the 338 received abstracts which are published in this volume. The meeting also offers the opportunity for the researchers to exchange information with each other, often leading to the initiation of collaborative studies. Both the number of members of the society and those participating in the annual meeting is ...

In-vivo Optical Imaging of Cortical Architecture and Dynamics

Modern Techniques in Neuroscience Research, 1999

Motor-Sensory Confluence in Tactile Perception

The Journal of Neuroscience, 2012

Perception involves motor control of sensory organs. However, the dynamics underlying emergence o... more Perception involves motor control of sensory organs. However, the dynamics underlying emergence of perception from motor-sensory interactions are not yet known. Two extreme possibilities are as follows: (1) motor and sensory signals interact within an open-loop scheme in which motor signals determine sensory sampling but are not affected by sensory processing and (2) motor and sensory signals are affected by each other within a closed-loop scheme. We studied the scheme of motor-sensory interactions in humans using a novel object localization task that enabled monitoring the relevant overt motor and sensory variables. We found that motor variables were dynamically controlled within each perceptual trial, such that they gradually converged to steady values. Training on this task resulted in improvement in perceptual acuity, which was achieved solely by changes in motor variables, without any change in the acuity of sensory readout. The within-trial dynamics is captured by a hierarchic...

Layer-Specific Touch-Dependent Facilitation and Depression in the Somatosensory Cortex during Active Whisking

The Journal of Neuroscience, 2006

Brains adapt to new situations by retuning their neurons. The most common form of neuronal adapta... more Brains adapt to new situations by retuning their neurons. The most common form of neuronal adaptation, typically observed with repetitive stimulations of passive sensory organs, is depression (responses gradually decrease until stabilized). We studied cortical adaptation when stimuli are acquired by active movements of the sensory organ. In anesthetized rats, artificial whisking was induced at 5 Hz, and activity of individual neurons in layers 2–5 was recorded during whisking in air (Whisking condition) and whisking against an object (Touch condition). Response strengths were assessed by spike counts. Input-layer responses (layers 4 and 5a) usually facilitated during the whisking train, whereas superficial responses (layer 2/3) usually depressed. In layers 2/3 and 4, but not 5a, responses were usually stronger during touch trials than during whisking in air. Facilitations were specific to the protraction phase; during retraction, responses depressed in all layers and conditions. The...

Dependence of Cortical Plasticity on Correlated Activity of Single Neurons and on Behavioral Context

Science, 1992

Dynamics of Depolarization and Hyperpolarization in the Frontal Cortex and Saccade Goal

Science, 2002

The frontal eye field and neighboring area 8Ar of the primate cortex are involved in programming ... more The frontal eye field and neighboring area 8Ar of the primate cortex are involved in programming and execution of saccades. Electrical microstimulation in these regions elicits short-latency contralateral saccades. To determine how spatiotemporal dynamics of microstimulation-evoked activity are converted into saccade plans, we used a combination of real-time optical imaging and microstimulation in behaving monkeys. Short stimulation trains evoked a rapid and widespread wave of depolarization followed by unexpected large and prolonged hyperpolarization. During this hyperpolarization saccades are almost exclusively ipsilateral, suggesting an important role for hyperpolarization in determining saccade goal.

Linking Spontaneous Activity of Single Cortical Neurons and the Underlying Functional Architecture

Science, 1999

The relation between the activity of a single neocortical neuron and the dynamics of the network ... more The relation between the activity of a single neocortical neuron and the dynamics of the network in which it is embedded was explored by single-unit recordings and real-time optical imaging. The firing rate of a spontaneously active single neuron strongly depends on the instantaneous spatial pattern of ongoing population activity in a large cortical area. Very similar spatial patterns of population activity were observed both when the neuron fired spontaneously and when it was driven by its optimal stimulus. The evoked patterns could be used to reconstruct the spontaneous activity of single neurons.

Never Resting Brain: Simultaneous Representation of Two Alpha Related Processes in Humans

PLoS ONE, 2008

Brain activity is continuously modulated, even at ''rest''. The alpha rhythm (8-12 Hz) has been k... more Brain activity is continuously modulated, even at ''rest''. The alpha rhythm (8-12 Hz) has been known as the hallmark of the brain's idle-state. However, it is still debated if the alpha rhythm reflects synchronization in a distributed network or focal generator and whether it occurs spontaneously or is driven by a stimulus. This EEG/fMRI study aimed to explore the source of alpha modulations and their distribution in the resting brain. By serendipity, while computing the individually defined power modulations of the alpha-band, two simultaneously occurring components of these modulations were found. An 'induced alpha' that was correlated with the paradigm (eyes open/ eyes closed), and a 'spontaneous alpha' that was ongoing and unrelated to the paradigm. These alpha components when used as regressors for BOLD activation revealed two segregated activation maps: the 'induced map' included left lateral temporal cortical regions and the hippocampus; the 'spontaneous map' included prefrontal cortical regions and the thalamus. Our combined fMRI/EEG approach allowed to computationally untangle two parallel patterns of alpha modulations and underpin their anatomical basis in the human brain. These findings suggest that the human alpha rhythm represents at least two simultaneously occurring processes which characterize the 'resting brain'; one is related to expected change in sensory information, while the other is endogenous and independent of stimulus change.

Interhemispheric correlations of slow spontaneous neuronal fluctuations revealed in human sensory cortex

Nature Neuroscience, 2008

Animal studies have shown robust electrophysiological activity in the sensory cortex in the absen... more Animal studies have shown robust electrophysiological activity in the sensory cortex in the absence of stimuli or tasks. Similarly, recent human functional magnetic resonance imaging (fMRI) revealed widespread, spontaneously emerging cortical fluctuations. However, it is unknown what neuronal dynamics underlie this spontaneous activity in the human brain. Here we studied this issue by combining bilateral single-unit, local field potentials (LFPs) and intracranial electrocorticography (ECoG) recordings in individuals undergoing clinical monitoring. We found slow (<0.1 Hz, following 1/f-like profiles) spontaneous fluctuations of neuronal activity with significant interhemispheric correlations. These fluctuations were evident mainly in neuronal firing rates and in gamma (40-100 Hz) LFP power modulations. Notably, the interhemispheric correlations were enhanced during rapid eye movement and stage 2 sleep. Multiple intracranial ECoG recordings revealed clear selectivity for functional networks in the spontaneous gamma LFP power modulations. Our results point to slow spontaneous modulations in firing rate and gamma LFP as the likely correlates of spontaneous fMRI fluctuations in the human sensory cortex. The neuronal events occurring in the sensory cortex when no stimulus is presented are not well understood. Contrary to traditional feed-forward models of information processing, a growing body of single-unit, LFP, electroencephalography (EEG), and optical imaging data point to robust levels of spontaneous neuronal activity in sensory areas of the mammalian cortex 1-7 . The modulation of such spontaneous neuronal activity can occur on very slow time scales 8, 9 . These robust spontaneous waves pose a challenge for models linking neuronal activity and sensory perception 10,11 , namely in explaining how the brain distinguishes between spontaneous events and vivid sensory percepts. One possibility is that the precise neuronal dynamics differ substantially between spontaneous and sensory-evoked conditions. This