Decision letter: Neuronal populations in the occipital cortex of the blind synchronize to the temporal dynamics of speech

The occipital cortex of early blind individuals (EB) activates during speech processing, challenging the notion of a hard-wired neurobiology of language. But, at what stage of speech processing do occipital regions participate in EB? Here we demonstrate that parieto-occipital regions in EB enhance their synchronization to acoustic fluctuations in human speech in the theta-range (corresponding to syllabic rate), irrespective of speech intelligibility. Crucially, enhanced synchronization to the intelligibility of speech was selectively observed in primary visual cortex in EB, suggesting that this region is at the interface between speech perception and comprehension. Moreover, EB showed overall enhanced functional connectivity between temporal and occipital cortices that are sensitive to speech intelligibility and altered directionality when compared to the sighted group. These findings suggest that the occipital cortex of the blind adopts an architecture that allows the tracking of speech material, and therefore does not fully abstract from the reorganized sensory inputs it receives.

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Neuronal populations in the occipital cortex of the blind synchronize to the temporal dynamics of speech

10.1101/186338 ◽

2017 ◽

Cited By ~ 1

Author(s):

Markus J. van Ackeren ◽

Francesca Barbero ◽

Stefania Mattioni ◽

Roberto Bottini ◽

Olivier Collignon

Keyword(s):

Visual Cortex ◽

Speech Processing ◽

Speech Intelligibility ◽

Temporal Dynamics ◽

Occipital Cortex ◽

Sensory Inputs ◽

Neuronal Populations ◽

Acoustic Fluctuations ◽

Blind Individuals ◽

Theta Range

AbstractThe occipital cortex of early blind individuals (EB) activates during speech processing, challenging the notion of a hard-wired neurobiology of language. But, at what stage of speech processing do occipital regions participate in EB?Here we demonstrate that parieto-occipital regions in EB enhance their synchronization to acoustic fluctuations in human speech in the theta-range (corresponding to syllabic rate), irrespective of speech intelligibility. Crucially, enhanced synchronization to the intelligibility of speech was selectively observed in primary visual cortex in EB, suggesting that this region is at the interface between speech perception and comprehension. Moreover, EB showed overall enhanced functional connectivity between temporal and occipital cortices sensitive to speech intelligibility and altered directionality when compared to the sighted group. These findings suggest that the occipital cortex of the blind adopts an architecture allowing the tracking of speech material, and therefore does not fully abstract from the reorganized sensory inputs it receives.

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Author response: Neuronal populations in the occipital cortex of the blind synchronize to the temporal dynamics of speech

10.7554/elife.31640.011 ◽

2018 ◽

Author(s):

Markus Johannes Van Ackeren ◽

Francesca M Barbero ◽

Stefania Mattioni ◽

Roberto Bottini ◽

Olivier Collignon

Keyword(s):

Temporal Dynamics ◽

Occipital Cortex ◽

Author Response ◽

Neuronal Populations

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EEG microstates of dreams

Scientific Reports ◽

10.1038/s41598-020-74075-z ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 2

Author(s):

Lucie Bréchet ◽

Denis Brunet ◽

Lampros Perogamvros ◽

Giulio Tononi ◽

Christoph M. Michel

Keyword(s):

Temporal Dynamics ◽

Conscious Experience ◽

Low Frequency ◽

Nrem Sleep ◽

Occipital Cortex ◽

Perceptual Content ◽

Frequency Synchronization ◽

Dream Recall ◽

Brain States ◽

Waking Up

Abstract Why do people sometimes report that they remember dreams, while at other times they recall no experience? Despite the interest in dreams that may happen during the night, it has remained unclear which brain states determine whether these conscious experiences will occur and what prevents us from waking up during these episodes. Here we address this issue by comparing the EEG activity preceding awakenings with recalled vs. no recall of dreams using the EEG microstate approach. This approach characterizes transiently stable brain states of sub-second duration that involve neural networks with nearly synchronous dynamics. We found that two microstates (3 and 4) dominated during NREM sleep compared to resting wake. Further, within NREM sleep, microstate 3 was more expressed during periods followed by dream recall, whereas microstate 4 was less expressed. Source localization showed that microstate 3 encompassed the medial frontal lobe, whereas microstate 4 involved the occipital cortex, as well as thalamic and brainstem structures. Since NREM sleep is characterized by low-frequency synchronization, indicative of neuronal bistability, we interpret the increased presence of the “frontal” microstate 3 as a sign of deeper local deactivation, and the reduced presence of the “occipital” microstate 4 as a sign of local activation. The latter may account for the occurrence of dreaming with rich perceptual content, while the former may account for why the dreaming brain may undergo executive disconnection and remain asleep. This study demonstrates that NREM sleep consists of alternating brain states whose temporal dynamics determine whether conscious experience arises.

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Brain network dynamics are hierarchically organized in time

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1705120114 ◽

2017 ◽

Vol 114 (48) ◽

pp. 12827-12832 ◽

Cited By ~ 192

Author(s):

Diego Vidaurre ◽

Stephen M. Smith ◽

Mark W. Woolrich

Keyword(s):

Large Scale ◽

Temporal Dynamics ◽

Brain Network ◽

Specific Measure ◽

Brain Areas ◽

Neuronal Populations ◽

Subject Specific ◽

Large Scale Networks ◽

Network Patterns ◽

The Brain

The brain recruits neuronal populations in a temporally coordinated manner in task and at rest. However, the extent to which large-scale networks exhibit their own organized temporal dynamics is unclear. We use an approach designed to find repeating network patterns in whole-brain resting fMRI data, where networks are defined as graphs of interacting brain areas. We find that the transitions between networks are nonrandom, with certain networks more likely to occur after others. Further, this nonrandom sequencing is itself hierarchically organized, revealing two distinct sets of networks, or metastates, that the brain has a tendency to cycle within. One metastate is associated with sensory and motor regions, and the other involves areas related to higher order cognition. Moreover, we find that the proportion of time that a subject spends in each brain network and metastate is a consistent subject-specific measure, is heritable, and shows a significant relationship with cognitive traits.

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Eccentricity Mapping of the Human Visual Cortex to Evaluate Temporal Dynamics of Functional T1ρ Mapping

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2015.94 ◽

2015 ◽

Vol 35 (7) ◽

pp. 1213-1219 ◽

Cited By ~ 10

Author(s):

Hye-Young Heo ◽

John A Wemmie ◽

Casey P Johnson ◽

Daniel R Thedens ◽

Vincent A Magnotta

Keyword(s):

Blood Flow ◽

Visual Cortex ◽

Temporal Dynamics ◽

Occipital Cortex ◽

Hemodynamic Response ◽

Proton Exchange ◽

Blood Oxygenation ◽

Human Visual Cortex ◽

Tissue Metabolism ◽

Oxygenation Level

Recent experiments suggest that T1 relaxation in the rotating frame ( T1ρ) is sensitive to metabolism and can detect localized activity-dependent changes in the human visual cortex. Current functional magnetic resonance imaging (fMRI) methods have poor temporal resolution due to delays in the hemodynamic response resulting from neurovascular coupling. Because T1ρ is sensitive to factors that can be derived from tissue metabolism, such as pH and glucose concentration via proton exchange, we hypothesized that activity-evoked T1ρ changes in visual cortex may occur before the hemodynamic response measured by blood oxygenation level-dependent (BOLD) and arterial spin labeling (ASL) contrast. To test this hypothesis, functional imaging was performed using BOLD, and ASL in human participants viewing an expanding ring stimulus. We calculated eccentricity phase maps across the occipital cortex for each functional signal and compared the temporal dynamics of T1ρ versus BOLD and ASL. The results suggest that T1ρ changes precede changes in the two blood flow-dependent measures. These observations indicate that T1ρ detects a signal distinct from traditional fMRI contrast methods. In addition, these findings support previous evidence that T1ρ is sensitive to factors other than blood flow, volume, or oxygenation. Furthermore, they suggest that tissue metabolism may be driving activity-evoked T1ρ changes.

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The temporal dynamics of the effects in occipital cortex of visual-spatial selective attention

Cognitive Brain Research ◽

10.1016/s0926-6410(02)00212-4 ◽

2002 ◽

Vol 15 (1) ◽

pp. 1-15 ◽

Cited By ~ 79

Author(s):

M.G Woldorff ◽

M Liotti ◽

M Seabolt ◽

L Busse ◽

J.L Lancaster ◽

...

Keyword(s):

Selective Attention ◽

Temporal Dynamics ◽

Occipital Cortex ◽

Visual Spatial

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TMS to the Lateral Occipital Cortex Disrupts Object Processing but Facilitates Scene Processing

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00095 ◽

2011 ◽

Vol 23 (12) ◽

pp. 4174-4184 ◽

Cited By ~ 31

Author(s):

Caitlin R. Mullin ◽

Jennifer K. E. Steeves

Keyword(s):

Temporal Dynamics ◽

Scene Perception ◽

Visual Image ◽

Object Perception ◽

Occipital Cortex ◽

Brain Regions ◽

Object Processing ◽

Repetitive Tms ◽

Scene Processing ◽

Lateral Occipital Cortex

The study of brain-damaged patients and advancements in neuroimaging have lead to the discovery of discrete brain regions that process visual image categories, such as objects and scenes. However, how these visual image categories interact remains unclear. For example, is scene perception simply an extension of object perception, or can global scene “gist” be processed independently of its component objects? Specifically, when recognizing a scene such as an “office,” does one need to first recognize its individual objects, such as the desk, chair, lamp, pens, and paper to build up the representation of an “office” scene? Here, we show that temporary interruption of object processing through repetitive TMS to the left lateral occipital cortex (LO), an area known to selectively process objects, impairs object categorization but surprisingly facilitates scene categorization. This result was replicated in a second experiment, which assessed the temporal dynamics of this disruption and facilitation. We further showed that repetitive TMS to left LO significantly disrupted object processing but facilitated scene processing when stimulation was administered during the first 180 msec of the task. This demonstrates that the visual system retains the ability to process scenes during disruption to object processing. Moreover, the facilitation of scene processing indicates disinhibition of areas involved in global scene processing, likely caused by disrupting inhibitory contributions from the LO. These findings indicate separate but interactive pathways for object and scene processing and further reveal a network of inhibitory connections between these visual brain regions.

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Spatial and temporal heterogeneity of neural responses in human posteromedial cortex

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1721714115 ◽

2018 ◽

Vol 115 (18) ◽

pp. 4785-4790 ◽

Cited By ~ 10

Author(s):

Amy L. Daitch ◽

Josef Parvizi

Keyword(s):

Active Sites ◽

Temporal Dynamics ◽

Human Subjects ◽

High Temporal Resolution ◽

Neuronal Populations ◽

Spatial And Temporal Heterogeneity ◽

Autobiographical Recall ◽

Transient Activity ◽

Rest Condition ◽

Spontaneous Thought

Neuroimaging evidence supports a role of the default mode network (DMN) in spontaneous thought and goal-driven internally oriented processes, such as recalling an autobiographical event, and has demonstrated its deactivation during focused, externally oriented attention. Recent work suggests that the DMN is not a homogeneous network but rather is composed of at least several subnetworks, which are engaged in distinct functions; however, it is still unclear if these different functions rely on the same neuronal populations. In this study, we used intracranial EEG to record from the posteromedial cortex (PMC), a core hub of the DMN, in 13 human subjects, during autobiographical memory retrieval (internally oriented), arithmetic processing (externally oriented), and cued rest (spontaneous thought), allowing us to measure activity from anatomically precise PMC sites with high temporal resolution. We observed a heterogeneous, yet spatially organized, pattern of activity across tasks. Many sites, primarily in the more ventral portion of PMC, were engaged during autobiographical recall and suppressed during arithmetic processing. Other more dorsal PMC sites were engaged during the cued-rest condition. Of these rest-active sites, some exhibited variable temporal dynamics across trials, possibly reflecting various forms of spontaneous thought, while others showed only transient activity at the beginning of cued-rest trials (i.e., after a switch from a task to cued rest), possibly involved in shifting the brain from a more focused to a more exploratory attentional state. These results suggest heterogeneity of function even within an individual node of the DMN.

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Brain networks processing temporal information in dynamic facial expressions

10.1101/819276 ◽

2019 ◽

Author(s):

Rafal M. Skiba ◽

Patrik Vuilleumier

Keyword(s):

Temporal Dynamics ◽

Inferior Frontal Gyrus ◽

Occipital Cortex ◽

Anterior Cingulate ◽

Spatial Processing ◽

Emotional Expressions ◽

Global Motion ◽

Facial Movements ◽

The Right

AbstractPerception of emotional expressions in faces relies on the integration of distinct facial features. We used fMRI to examine the role of local and global motion information in facial movements during exposure to novel dynamic face stimuli. We found that synchronous expressions distinctively engaged medial prefrontal areas in the ventral anterior cingulate cortex (vACC), supplementary premotor areas, and bilateral superior frontal gyrus (global temporal-spatial processing). Asynchronous expressions in which one part of the face (e.g., eyes) unfolded before the other (e.g., mouth) activated more the right superior temporal sulcus (STS) and inferior frontal gyrus (local temporal-spatial processing). DCM analysis further showed that processing of asynchronous expression features was associated with a differential information flow, centered on STS, which received direct input from occipital cortex and projected to the amygdala. Moreover, STS and amygdala displayed selective interactions with vACC where the integration of both local and global motion cues (present in synchronous expressions) could take place. These results provide new evidence for a role of both local and global temporal dynamics in emotional expressions, extracted in partly separate brain pathways. Importantly, we show that dynamic expressions with synchronous movement cues may distinctively engage brain areas responsible for motor execution of expressions.

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