scholarly journals Differentiating the Functional Contributions of Resting Connectivity Networks to Memory Decision-making: fMRI Support for Multistage Control Processes

2015 ◽  
Vol 27 (8) ◽  
pp. 1617-1632 ◽  
Author(s):  
Ravi D. Mill ◽  
Ian Cavin ◽  
Akira R. O'Connor
Keyword(s):  
Large Scale ◽  
Time Course ◽  
Recognition Task ◽  
Neural Substrates ◽  
Conflict Detection ◽  
Opposite Pattern ◽  
Control Processes ◽  
Fmri Study ◽  
Control Response ◽  
Memory Control

Neural substrates of memory control are engaged when participants encounter unexpected mnemonic stimuli (e.g., a new word when told to expect an old word). The present fMRI study (n = 18) employed the likelihood cueing recognition task to elucidate the role of functional connectivity (fcMRI) networks in supporting memory control processes engaged by these unexpected events. Conventional task-evoked BOLD analyses recovered a memory control network similar to that previously reported, comprising medial prefrontal, lateral prefrontal, and inferior parietal regions. These were split by their differential affiliation to distinct fcMRI networks (“conflict detection” and “confirmatory retrieval” networks). Subsequent ROI analyses clarified the functional significance of this connectivity differentiation, with “conflict” network-affiliated regions specifically sensitive to cue strength, but not to response confidence, and “retrieval” network-affiliated regions showing the opposite pattern. BOLD time course analyses corroborated the segregation of memory control regions into “early” conflict detection and “late” retrieval analysis, with both processes underlying the allocation of memory control. Response specificity and time course findings were generalized beyond task-recruited ROIs to clusters within the large-scale fcMRI networks, suggesting that this connectivity architecture could underlie efficient processing of distinct processes within cognitive tasks. The findings raise important parallels between prevailing theories of memory and cognitive control.

scholarly journals What Makes Eye Contact Special? Neural Substrates of On-Line Mutual Eye-Gaze: A Hyperscanning fMRI Study

eNeuro ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. ENEURO.0284-18.2019 ◽  
Author(s):  
Takahiko Koike ◽  
Motofumi Sumiya ◽  
Eri Nakagawa ◽  
Shuntaro Okazaki ◽  
Norihiro Sadato
Keyword(s):  
Eye Gaze ◽  
Eye Contact ◽  
Neural Substrates ◽  
Fmri Study ◽  
On Line

The Time Course of Changes during Motor Sequence Learning: A Whole-Brain fMRI Study

NeuroImage ◽  
1998 ◽  
Vol 8 (1) ◽  
pp. 50-61 ◽  
Author(s):  
Ivan Toni ◽  
Michael Krams ◽  
Robert Turner ◽  
Richard E. Passingham
Keyword(s):  
Sequence Learning ◽  
Time Course ◽  
Motor Sequence Learning ◽  
Motor Sequence ◽  
Whole Brain ◽  
Fmri Study ◽  
Brain Fmri

Parameter Space Analysis Suggests Multi-Site Plasticity Contributes to Motor Pattern Initiation in Tritonia

2007 ◽  
Vol 98 (4) ◽  
pp. 2382-2398 ◽  
Author(s):  
Robert J. Calin-Jageman ◽  
Mark J. Tunstall ◽  
Brett D. Mensh ◽  
Paul S. Katz ◽  
William N. Frost
Keyword(s):  
Parameter Space ◽  
Large Scale ◽  
Time Course ◽  
Scale Parameter ◽  
Motor Pattern ◽  
Rhythmic Activity ◽  
Excitatory Input ◽  
Space Analysis ◽  
Gastropod Mollusk ◽  
Detailed Simulation

This research examines the mechanisms that initiate rhythmic activity in the episodic central pattern generator (CPG) underlying escape swimming in the gastropod mollusk Tritonia diomedea. Activation of the network is triggered by extrinsic excitatory input but also accompanied by intrinsic neuromodulation and the recruitment of additional excitation into the circuit. To examine how these factors influence circuit activation, a detailed simulation of the unmodulated CPG network was constructed from an extensive set of physiological measurements. In this model, extrinsic input alone is insufficient to initiate rhythmic activity, confirming that additional processes are involved in circuit activation. However, incorporating known neuromodulatory and polysynaptic effects into the model still failed to enable rhythmic activity, suggesting that additional circuit features are also required. To delineate the additional activation requirements, a large-scale parameter-space analysis was conducted (∼2 × 106 configurations). The results suggest that initiation of the swim motor pattern requires substantial reconfiguration at multiple sites within the network, especially to recruit ventral swim interneuron-B (VSI) activity and increase coupling between the dorsal swim interneurons (DSIs) and cerebral neuron 2 (C2) coupling. Within the parameter space examined, we observed a tendency for rhythmic activity to be spontaneous and self-sustaining. This suggests that initiation of episodic rhythmic activity may involve temporarily restructuring a nonrhythmic network into a persistent oscillator. In particular, the time course of neuromodulatory effects may control both activation and termination of rhythmic bursting.

scholarly journals Large-scale Dynamics of Perceptual Decision Information across Human Cortex

2020 ◽  
Author(s):  
Niklas Wilming ◽  
Peter R Murphy ◽  
Florent Meyniel ◽  
Tobias H Donner
Keyword(s):  
Large Scale ◽  
Time Course ◽  
Action Plan ◽  
Frequency Channel ◽  
Human Cortex ◽  
Cortical Hierarchy ◽  
Specific Frequency ◽  
Sensory Evidence ◽  
Visual Cortical ◽  
Endogenous Component

AbstractPerceptual decisions entail the accumulation of sensory evidence for a particular choice towards an action plan. An influential framework holds that sensory cortical areas encode the instantaneous sensory evidence and downstream, action-related regions accumulate this evidence. The large-scale distribution of this computation across the cerebral cortex has remained largely elusive. We developed a regionally-specific magnetoencephalography decoding approach to exhaustively map the dynamics of stimulus- and choice-specific signals across the human cortical surface during a visual decision. Comparison with the evidence accumulation dynamics inferred from behavior enabled us to disentangle stimulus-dependent and endogenous components of choice-predictive activity across the visual cortical hierarchy. The endogenous component was present in primary visual cortex, expressed in a low (< 20 Hz) frequency-band, and its time course tracked, with delay, the build-up of choice-predictive activity in (pre-)motor regions. Our results are consistent with choice-specific cortical feedback signaling in a specific frequency channel during decision formation.

scholarly journals Is Pupil Activity Associated With the Strength of Memory Signal for Words in a Continuous Recognition Memory Paradigm?

2021 ◽  
Vol 12 ◽  
Author(s):  
Jorge Oliveira ◽  
Marta Fernandes ◽  
Pedro J. Rosa ◽  
Pedro Gamito
Keyword(s):  
Retention Interval ◽  
Recognition Memory ◽  
Pupil Size ◽  
Time Course ◽  
Recognition Performance ◽  
Recognition Task ◽  
Subjective Feeling ◽  
Consistent Finding ◽  
Pupillary Responses ◽  
Study Test

Research on pupillometry provides an increasing evidence for associations between pupil activity and memory processing. The most consistent finding is related to an increase in pupil size for old items compared with novel items, suggesting that pupil activity is associated with the strength of memory signal. However, the time course of these changes is not completely known, specifically, when items are presented in a running recognition task maximizing interference by requiring the recognition of the most recent items from a sequence of old/new items. The sample comprised 42 healthy participants who performed a visual word recognition task under varying conditions of retention interval. Recognition responses were evaluated using behavioral variables for discrimination accuracy, reaction time, and confidence in recognition decisions. Pupil activity was recorded continuously during the entire experiment. The results suggest a decrease in recognition performance with increasing study-test retention interval. Pupil size decreased across retention intervals, while pupil old/new effects were found only for words recognized at the shortest retention interval. Pupillary responses consisted of a pronounced early pupil constriction at retrieval under longer study-test lags corresponding to weaker memory signals. However, the pupil size was also sensitive to the subjective feeling of familiarity as shown by pupil dilation to false alarms (new items judged as old). These results suggest that the pupil size is related not only to the strength of memory signal but also to subjective familiarity decisions in a continuous recognition memory paradigm.

Spinal cord neural activity of patients with fibromyalgia and healthy controls during temporal summation of pain: an fMRI study

2021 ◽  
Vol 126 (3) ◽  
pp. 946-956
Author(s):  
Roland Staud ◽  
Jeff Boissoneault ◽  
Song Lai ◽  
Marlin S. Mejia ◽  
Riddhi Ramanlal ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Chronic Pain ◽  
Neural Activity ◽  
Central Sensitization ◽  
Temporal Summation ◽  
Time Course ◽  
Pain Modulation ◽  
Healthy Controls ◽  
Fmri Study ◽  
Second Pain

“Windup” and its behavioral correlate “temporal-summation-of-second pain” (TSSP) represent spinal cord mechanisms of pain augmentation associated with central sensitization and chronic pain. Fibromyalgia (FM) is a chronic pain disorder, where abnormal TSSP has been demonstrated. We used fMRI to study spinal cord and brainstem activation during TSSP. We characterized the time course of spinal cord and brainstem BOLD activity during TSSP which showed abnormal brainstem activity in patients with FM, possibly due to deficient pain modulation.

Short-term emersion affects cardiac function and regional haemolymph distribution in the crab Cancer magister

1996 ◽  
Vol 199 (3) ◽  
pp. 569-578
Author(s):  
C Airriess ◽  
B Mcmahon
Keyword(s):  
Stroke Volume ◽  
Cardiac Function ◽  
Large Scale ◽  
Time Course ◽  
Beat Frequency ◽  
Heart Beat ◽  
Experimental Chamber ◽  
Cancer Magister ◽  
Flow Through ◽  
Cardiac Stroke Volume

Changes in cardiac function and arterial haemolymph flow associated with 6 h of emersion were investigated in the crab Cancer magister using an ultrasonic flowmeter. This species is usually found sublittorally but, owing to the large-scale horizontal water movements associated with extreme tides, C. magister may occasionally become stranded on the beach. Laboratory experiments were designed such that the emersion period was typical of those that might be experienced by this crab in its natural environment. The frequency of the heart beat began to decline sharply almost immediately after the start of the experimental emersion period. Cardiac stroke volume fell more gradually. The combined reduction in these two variables led to a maximum decrease in cardiac output of more than 70 % from the control rate. Haemolymph flow through all the arteries originating at the heart, with the exception of the anterior aorta, also declined markedly during emersion. As the water level in the experimental chamber fell below the inhalant branchial openings, a stereotypical, dramatic increase in haemolymph flow through the anterior aorta began and this continued for the duration of the emersion period. The rapid time course of the decline in heart-beat frequency and the increase in haemolymph flow through the anterior aorta suggest a neural mechanism responding to the absence of ventilatory water in the branchial chambers. These responses may be adaptations, respectively, to conserve energy by reducing the minute volume of haemolymph pumped by the heart and to protect the supply of haemolymph to cephalic elements of the central nervous system. The decline in cardiac stroke volume, which occurs more slowly over the emersion period, may be a passive result of the failure to supply sufficient O2 to meet the aerobic demands of the cardiac ganglion.

scholarly journals Large-Scale Desynchronization During Interictal Epileptic Discharges Recorded With Intracranial EEG

2020 ◽  
Vol 11 ◽  
Author(s):  
Elie Bou Assi ◽  
Younes Zerouali ◽  
Manon Robert ◽  
Frederic Lesage ◽  
Philippe Pouliot ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Large Scale ◽  
Time Course ◽  
Deep Understanding ◽  
Epileptic Focus ◽  
Epileptogenic Focus ◽  
Intracranial Eeg ◽  
Epileptiform Discharges ◽  
Potential Biomarker ◽  
Epileptic Discharges

It is increasingly recognized that deep understanding of epileptic seizures requires both localizing and characterizing the functional network of the region where they are initiated, i. e., the epileptic focus. Previous investigations of the epileptogenic focus' functional connectivity have yielded contrasting results, reporting both pathological increases and decreases during resting periods and seizures. In this study, we shifted paradigm to investigate the time course of connectivity in relation to interictal epileptiform discharges. We recruited 35 epileptic patients undergoing intracranial EEG (iEEG) investigation as part of their presurgical evaluation. For each patient, 50 interictal epileptic discharges (IEDs) were marked and iEEG signals were epoched around those markers. Signals were narrow-band filtered and time resolved phase-locking values were computed to track the dynamics of functional connectivity during IEDs. Results show that IEDs are associated with a transient decrease in global functional connectivity, time-locked to the peak of the discharge and specific to the high range of the gamma frequency band. Disruption of the long-range connectivity between the epileptic focus and other brain areas might be an important process for the generation of epileptic activity. Transient desynchronization could be a potential biomarker of the epileptogenic focus since 1) the functional connectivity involving the focus decreases significantly more than the connectivity outside the focus and 2) patients with good surgical outcome appear to have a significantly more disconnected focus than patients with bad outcomes.

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