Eric Maris - Academia.edu (original) (raw)
Papers by Eric Maris
PloS one, 2015
The neural response to a stimulus is influenced by endogenous factors such as expectation and att... more The neural response to a stimulus is influenced by endogenous factors such as expectation and attention. Current research suggests that expectation and attention exert their effects in opposite directions, where expectation decreases neural activity in sensory areas, while attention increases it. However, expectation and attention are usually studied either in isolation or confounded with each other. A recent study suggests that expectation and attention may act jointly on sensory processing, by increasing the neural response to expected events when they are attended, but decreasing it when they are unattended. Here we test this hypothesis in an auditory temporal cueing paradigm using magnetoencephalography in humans. In our study participants attended to, or away from, tones that could arrive at expected or unexpected moments. We found a decrease in auditory beta band synchrony to expected (versus unexpected) tones if they were unattended, but no difference if they were attended. M...
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Neural oscillations have emerged as one of the major electrophysiological phenomena investigated ... more Neural oscillations have emerged as one of the major electrophysiological phenomena investigated in cognitive and systems neuroscience. These oscillations are typically studied with regard to their amplitude, phase, and/or phase coupling. Here we demonstrate the existence of another property that is intrinsic to neural oscillations but has hitherto remained largely unexplored in cognitive and systems neuroscience. This pertains to the notion that these oscillations show reliable diversity in their phase-relations between neighboring recording sites (phase-relation diversity). In contrast to most previous work, we demonstrate that this diversity is restricted neither to low-frequency oscillations nor to periods outside of sensory stimulation. On the basis of magnetoencephalographic (MEG) recordings in humans, we show that this diversity is prominent not only for ongoing alpha oscillations (8-12 Hz) but also for gamma oscillations (50-70 Hz) that are induced by sustained visual stimulation. We further show that this diversity provides a dimension within electrophysiological data that, provided a sufficiently high signal-to-noise ratio, does not covary with changes in amplitude. These observations place phase-relation diversity on the map as a prominent and general property of neural oscillations that, moreover, can be studied with noninvasive methods in healthy human volunteers. This opens important new avenues for investigating how neural oscillations contribute to the neural implementation of cognition and behavior.
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Journal of Neuroscience, 2013
Neural oscillations in the beta band (15-30 Hz) occur coherently throughout the primate somatomot... more Neural oscillations in the beta band (15-30 Hz) occur coherently throughout the primate somatomotor network, comprising somatomotor cortices, basal ganglia, thalamus, cerebellum, and spinal cord, with the latter resulting in beta oscillations in muscular activity. In accordance with the anatomy of this network, these oscillations have traditionally been associated strictly with motor function. Here we show in humans that somatosensory demands, both in anticipation and during the processing of tactile stimuli, also modulate beta oscillations throughout this network. Specifically, somatosensory demands suppress the degree to which not only cortical activity but also muscular activity oscillates in the beta band. This suppression of muscular beta oscillations by perceptual demands is specific to demands in the somatosensory modality and occurs independent of movement preparation and execution: it occurs even when no movement is required at all. This places touch perception as an important computation within this widely distributed somatomotor beta network and suggests that, at least in healthy subjects, somatosensation and action should not be considered as separable processes, not even at the level of the muscles.
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Neuropsychologia, 2014
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NeuroImage, 2014
What are the spectral signatures of somatosensory attention? Here we show that the answer to this... more What are the spectral signatures of somatosensory attention? Here we show that the answer to this question depends critically on the sensory context in which attention is deployed. We recorded magnetoencephalography (MEG) in humans and investigated tactile spatial attention in two different sensory contexts: in anticipation and during the processing of sustained tactile stimuli. We observe a double dissociation between these contexts and two key electrophysiological correlates of attention: in anticipation we primarily observe an attentional suppression of contralateral alpha and beta oscillations (8-12 and 15-30 Hz, respectively), whereas during stimulus processing we primarily observe an attentional amplification of contralateral gamma oscillations (55-75 Hz). This dissociation is well explained by the different neural states that occur prior and during the stimulus, and on which attention can exert its influence. In line with analogous observations in the visual modality, this suggests that the neural implementation of attention must be understood in relation to context and existing brain states. Consequently, different signatures of attention may contribute to perception in different contexts and, as our data reveals for the attentional modulation of alpha oscillations, these are not always required for attention to improve perception. At the same time, these data demonstrate that the attentional modulations of alpha and gamma oscillations (during, respectively, attentional orienting and attentional selection), are generalizable phenomena across the different sensory modalities.
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Journal of Neuroscience Methods, 2014
We have developed a novel setup for rats that allows for controlled sensory input to an animal en... more We have developed a novel setup for rats that allows for controlled sensory input to an animal engaged in a task while recording both electrophysiological signals and behavioral output. Our setup is described in a companion paper. We validate our setup by replicating (1) the functionally nonspecific spread of neural activity following tactile stimulation, and (2) the effects of anesthesia on the tactile evoked responses. We also demonstrate for the first time that the ECoG can be used to record evoked responses in a signal that reflects neural output (spiking activity), and illustrate the usefulness of our setup by demonstrating that these evoked responses are modulated by both the phase of pre-stimulus oscillations and by expectation. Compared with high-density wire recordings, micro-ECoG offers a much more stable signal without readjustments, and a much better scalability. Compared with extracranial and regular ECoG recordings, micro-ECoG allows us to measure signals that reflect both neural input and neural output. For sensory and cognitive research, our setup provides a unique combination of possibilities that cannot be achieved in other setups for rodents.
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Cerebral Cortex, 2013
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Systems and cognitive neuroscience aim at understanding the neurophysiological mechanisms that un... more Systems and cognitive neuroscience aim at understanding the neurophysiological mechanisms that underlie cognition and behavior. Many studies have revealed the involvement of many types of neural signals in diverse cognitive and behavioral phenomena. Here, we go beyond establishing such involvement and address two fundamental, yet largely unaddressed, questions: 1) exactly how much does a given neural signal contribute to a cognitive or behavioral phenomenon of interest; and 2) to what extent are distinct neural signals independently related to this phenomenon? We recorded brain activity using magnetoencephalography while human participants performed a cued somatosensory detection task. Using a novel method, we then quantified the contribution (in a predictive but not causal sense) of two well-established neural phenomena to the improvement in perception with attentional orienting. In our sample, the anticipatory suppression of extracranially recorded oscillatory α- and β-band amplitudes from contralateral primary somatosensory cortex could account for maximally 29% of the attention-induced improvement in tactile perception. In addition, although amplitude suppressions in the α- and β-frequency bands both contributed to this improvement, their contribution was largely shared. These data reveal the upper limit of the cognitive/behavioral relevance of this type of signal and show that at least 71% of the perceptual improvement with attention must be accounted for by other signals.
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To establish the relative contribution of phonological and orthographic information to visual wor... more To establish the relative contribution of phonological and orthographic information to visual word recognition, we varied the instruction how to respond to the pseudohomophones in a Dutch lexical decision task. One participant group was asked to base their word/nonword decisions on spelling and therefore reject pseudohomophones together with the nonhomophonic nonwords; the other group had to base their decisions on phonology and therefore accept pseudohomophones together with real words. Rejecting pseudohomophones (ignoring phonological information) was accompanied by costs in speed and accuracy for the pseudohomophones but not for other items. Accepting pseudohomophones (ignoring orthographic information) led to speed and accuracy costs for pseudohomophones and nonhomophonic nonwords that were approximately ten times larger than those for rejecting pseudohomophones. The simultaneous costs for pseudohomophones and nonhomophonic nonwords contradict an explanation of pseudohomophone acceptance in terms of a postlexical spelling check. The results indicate that phonological information can be ignored much more easily than orthographic information. Therefore, they fail to support a primary role of sublexical phonological assembly in lexical decision. This conclusion was further supported by strong effects of phonological consistency that were found in a naming experiment but were completely absent in lexical decision.
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In this study, the effects of vigabatrin on spike-and-wave discharges (SWDs) were measured in WAG... more In this study, the effects of vigabatrin on spike-and-wave discharges (SWDs) were measured in WAG/Rij rats, an animal model of absence epilepsy. Vigabatrin was used with the aim of enhancing GABAergic neurotransmission, and in this way to investigate the role of this process in the properties of SWDs. The study was carried out both in the rat, in vivo, and also using a computational model, in order to test different mechanisms that may account for the changes in SWDs after vigabatrin. The model parameters, representing GABA levels, were changed according to the known, and assumed, mechanism of action of the drug. The results show that the computational model can most adequately simulate the data obtained in vivo on the assumption that the enhancement of GABAergic neurotransmission due to application of vigabatrin is most pronounced at the level of the thalamic relay nuclei (TC cells). Furthermore, vigabatrin was shown to affect both the SWD starting and stopping mechanisms, as refle...
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Neuronal oscillations are postulated to play a fundamental role in top-down processes of expectat... more Neuronal oscillations are postulated to play a fundamental role in top-down processes of expectation. We used magnetoencephalography (MEG) to investigate whether expectation of a tactile event involves a pre-stimulus modulation of neuronal oscillations in human somatosensory cortex. In a bimodal attention paradigm, participants were presented with a predictable spatio-temporal pattern of lateralized tactile stimulations and simultaneously occurring non-lateralized auditory stimuli. Before the onset of a series of such combined audio-tactile stimuli, a cue was presented that indicated the sensory stream that had to be attended. By investigating lateralized patterns of oscillatory activity, we were able to study both attentive (when the tactile stream was attended) and non-attentive (when the auditory stream was attended) tactile expectations. For both attention conditions, we observed a lateralized modulation of the amplitude of beta band oscillations prior to a predictable - and accordingly lateralized - tactile stimulus. As such, we show that anticipatory modulation of ongoing oscillatory activity is not restricted to attended sensory events. Attention did enlarge the size of this modulation. We argue that this modulation constitutes a suppression of beta oscillations that originate at least partly from primary somatosensory cortex (S1) contralateral to the expected stimulation. We discuss our results in the light of the hypothesis that ongoing beta oscillations over sensorimotor cortex reflect a brain state in which neuronal processing efficacy is low. Pre-stimulus suppression of these oscillations then prepares the system for future processing. This shows that perception is an active process that starts even prior to sensation.
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PloS one, 2015
The neural response to a stimulus is influenced by endogenous factors such as expectation and att... more The neural response to a stimulus is influenced by endogenous factors such as expectation and attention. Current research suggests that expectation and attention exert their effects in opposite directions, where expectation decreases neural activity in sensory areas, while attention increases it. However, expectation and attention are usually studied either in isolation or confounded with each other. A recent study suggests that expectation and attention may act jointly on sensory processing, by increasing the neural response to expected events when they are attended, but decreasing it when they are unattended. Here we test this hypothesis in an auditory temporal cueing paradigm using magnetoencephalography in humans. In our study participants attended to, or away from, tones that could arrive at expected or unexpected moments. We found a decrease in auditory beta band synchrony to expected (versus unexpected) tones if they were unattended, but no difference if they were attended. M...
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Neural oscillations have emerged as one of the major electrophysiological phenomena investigated ... more Neural oscillations have emerged as one of the major electrophysiological phenomena investigated in cognitive and systems neuroscience. These oscillations are typically studied with regard to their amplitude, phase, and/or phase coupling. Here we demonstrate the existence of another property that is intrinsic to neural oscillations but has hitherto remained largely unexplored in cognitive and systems neuroscience. This pertains to the notion that these oscillations show reliable diversity in their phase-relations between neighboring recording sites (phase-relation diversity). In contrast to most previous work, we demonstrate that this diversity is restricted neither to low-frequency oscillations nor to periods outside of sensory stimulation. On the basis of magnetoencephalographic (MEG) recordings in humans, we show that this diversity is prominent not only for ongoing alpha oscillations (8-12 Hz) but also for gamma oscillations (50-70 Hz) that are induced by sustained visual stimulation. We further show that this diversity provides a dimension within electrophysiological data that, provided a sufficiently high signal-to-noise ratio, does not covary with changes in amplitude. These observations place phase-relation diversity on the map as a prominent and general property of neural oscillations that, moreover, can be studied with noninvasive methods in healthy human volunteers. This opens important new avenues for investigating how neural oscillations contribute to the neural implementation of cognition and behavior.
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Journal of Neuroscience, 2013
Neural oscillations in the beta band (15-30 Hz) occur coherently throughout the primate somatomot... more Neural oscillations in the beta band (15-30 Hz) occur coherently throughout the primate somatomotor network, comprising somatomotor cortices, basal ganglia, thalamus, cerebellum, and spinal cord, with the latter resulting in beta oscillations in muscular activity. In accordance with the anatomy of this network, these oscillations have traditionally been associated strictly with motor function. Here we show in humans that somatosensory demands, both in anticipation and during the processing of tactile stimuli, also modulate beta oscillations throughout this network. Specifically, somatosensory demands suppress the degree to which not only cortical activity but also muscular activity oscillates in the beta band. This suppression of muscular beta oscillations by perceptual demands is specific to demands in the somatosensory modality and occurs independent of movement preparation and execution: it occurs even when no movement is required at all. This places touch perception as an important computation within this widely distributed somatomotor beta network and suggests that, at least in healthy subjects, somatosensation and action should not be considered as separable processes, not even at the level of the muscles.
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Neuropsychologia, 2014
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NeuroImage, 2014
What are the spectral signatures of somatosensory attention? Here we show that the answer to this... more What are the spectral signatures of somatosensory attention? Here we show that the answer to this question depends critically on the sensory context in which attention is deployed. We recorded magnetoencephalography (MEG) in humans and investigated tactile spatial attention in two different sensory contexts: in anticipation and during the processing of sustained tactile stimuli. We observe a double dissociation between these contexts and two key electrophysiological correlates of attention: in anticipation we primarily observe an attentional suppression of contralateral alpha and beta oscillations (8-12 and 15-30 Hz, respectively), whereas during stimulus processing we primarily observe an attentional amplification of contralateral gamma oscillations (55-75 Hz). This dissociation is well explained by the different neural states that occur prior and during the stimulus, and on which attention can exert its influence. In line with analogous observations in the visual modality, this suggests that the neural implementation of attention must be understood in relation to context and existing brain states. Consequently, different signatures of attention may contribute to perception in different contexts and, as our data reveals for the attentional modulation of alpha oscillations, these are not always required for attention to improve perception. At the same time, these data demonstrate that the attentional modulations of alpha and gamma oscillations (during, respectively, attentional orienting and attentional selection), are generalizable phenomena across the different sensory modalities.
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Journal of Neuroscience Methods, 2014
We have developed a novel setup for rats that allows for controlled sensory input to an animal en... more We have developed a novel setup for rats that allows for controlled sensory input to an animal engaged in a task while recording both electrophysiological signals and behavioral output. Our setup is described in a companion paper. We validate our setup by replicating (1) the functionally nonspecific spread of neural activity following tactile stimulation, and (2) the effects of anesthesia on the tactile evoked responses. We also demonstrate for the first time that the ECoG can be used to record evoked responses in a signal that reflects neural output (spiking activity), and illustrate the usefulness of our setup by demonstrating that these evoked responses are modulated by both the phase of pre-stimulus oscillations and by expectation. Compared with high-density wire recordings, micro-ECoG offers a much more stable signal without readjustments, and a much better scalability. Compared with extracranial and regular ECoG recordings, micro-ECoG allows us to measure signals that reflect both neural input and neural output. For sensory and cognitive research, our setup provides a unique combination of possibilities that cannot be achieved in other setups for rodents.
Bookmarks Related papers MentionsView impact
Cerebral Cortex, 2013
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Systems and cognitive neuroscience aim at understanding the neurophysiological mechanisms that un... more Systems and cognitive neuroscience aim at understanding the neurophysiological mechanisms that underlie cognition and behavior. Many studies have revealed the involvement of many types of neural signals in diverse cognitive and behavioral phenomena. Here, we go beyond establishing such involvement and address two fundamental, yet largely unaddressed, questions: 1) exactly how much does a given neural signal contribute to a cognitive or behavioral phenomenon of interest; and 2) to what extent are distinct neural signals independently related to this phenomenon? We recorded brain activity using magnetoencephalography while human participants performed a cued somatosensory detection task. Using a novel method, we then quantified the contribution (in a predictive but not causal sense) of two well-established neural phenomena to the improvement in perception with attentional orienting. In our sample, the anticipatory suppression of extracranially recorded oscillatory α- and β-band amplitudes from contralateral primary somatosensory cortex could account for maximally 29% of the attention-induced improvement in tactile perception. In addition, although amplitude suppressions in the α- and β-frequency bands both contributed to this improvement, their contribution was largely shared. These data reveal the upper limit of the cognitive/behavioral relevance of this type of signal and show that at least 71% of the perceptual improvement with attention must be accounted for by other signals.
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To establish the relative contribution of phonological and orthographic information to visual wor... more To establish the relative contribution of phonological and orthographic information to visual word recognition, we varied the instruction how to respond to the pseudohomophones in a Dutch lexical decision task. One participant group was asked to base their word/nonword decisions on spelling and therefore reject pseudohomophones together with the nonhomophonic nonwords; the other group had to base their decisions on phonology and therefore accept pseudohomophones together with real words. Rejecting pseudohomophones (ignoring phonological information) was accompanied by costs in speed and accuracy for the pseudohomophones but not for other items. Accepting pseudohomophones (ignoring orthographic information) led to speed and accuracy costs for pseudohomophones and nonhomophonic nonwords that were approximately ten times larger than those for rejecting pseudohomophones. The simultaneous costs for pseudohomophones and nonhomophonic nonwords contradict an explanation of pseudohomophone acceptance in terms of a postlexical spelling check. The results indicate that phonological information can be ignored much more easily than orthographic information. Therefore, they fail to support a primary role of sublexical phonological assembly in lexical decision. This conclusion was further supported by strong effects of phonological consistency that were found in a naming experiment but were completely absent in lexical decision.
Bookmarks Related papers MentionsView impact
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In this study, the effects of vigabatrin on spike-and-wave discharges (SWDs) were measured in WAG... more In this study, the effects of vigabatrin on spike-and-wave discharges (SWDs) were measured in WAG/Rij rats, an animal model of absence epilepsy. Vigabatrin was used with the aim of enhancing GABAergic neurotransmission, and in this way to investigate the role of this process in the properties of SWDs. The study was carried out both in the rat, in vivo, and also using a computational model, in order to test different mechanisms that may account for the changes in SWDs after vigabatrin. The model parameters, representing GABA levels, were changed according to the known, and assumed, mechanism of action of the drug. The results show that the computational model can most adequately simulate the data obtained in vivo on the assumption that the enhancement of GABAergic neurotransmission due to application of vigabatrin is most pronounced at the level of the thalamic relay nuclei (TC cells). Furthermore, vigabatrin was shown to affect both the SWD starting and stopping mechanisms, as refle...
Bookmarks Related papers MentionsView impact
Neuronal oscillations are postulated to play a fundamental role in top-down processes of expectat... more Neuronal oscillations are postulated to play a fundamental role in top-down processes of expectation. We used magnetoencephalography (MEG) to investigate whether expectation of a tactile event involves a pre-stimulus modulation of neuronal oscillations in human somatosensory cortex. In a bimodal attention paradigm, participants were presented with a predictable spatio-temporal pattern of lateralized tactile stimulations and simultaneously occurring non-lateralized auditory stimuli. Before the onset of a series of such combined audio-tactile stimuli, a cue was presented that indicated the sensory stream that had to be attended. By investigating lateralized patterns of oscillatory activity, we were able to study both attentive (when the tactile stream was attended) and non-attentive (when the auditory stream was attended) tactile expectations. For both attention conditions, we observed a lateralized modulation of the amplitude of beta band oscillations prior to a predictable - and accordingly lateralized - tactile stimulus. As such, we show that anticipatory modulation of ongoing oscillatory activity is not restricted to attended sensory events. Attention did enlarge the size of this modulation. We argue that this modulation constitutes a suppression of beta oscillations that originate at least partly from primary somatosensory cortex (S1) contralateral to the expected stimulation. We discuss our results in the light of the hypothesis that ongoing beta oscillations over sensorimotor cortex reflect a brain state in which neuronal processing efficacy is low. Pre-stimulus suppression of these oscillations then prepares the system for future processing. This shows that perception is an active process that starts even prior to sensation.
Bookmarks Related papers MentionsView impact