scholarly journals Waves of Change: Brain Sensitivity to Differential, not Absolute, Stimulus Intensity is Conserved Across Humans and Rats

2020 ◽  
Author(s):  
R Somervail ◽  
F Zhang ◽  
G Novembre ◽  
R J Bufacchi ◽  
Y Guo ◽  
...  
Keyword(s):  
Stimulus Intensity ◽  
Brain Activity ◽  
High Sensitivity ◽  
Mammalian Brain ◽  
Behavioral Reactions ◽  
Changing Environments ◽  
Absolute Intensities ◽  
Relative Contribution ◽  
Novel Objects ◽  
Sudden Appearance

Abstract Living in rapidly changing environments has shaped the mammalian brain toward high sensitivity to abrupt and intense sensory events—often signaling threats or affordances requiring swift reactions. Unsurprisingly, such events elicit a widespread electrocortical response (the vertex potential, VP), likely related to the preparation of appropriate behavioral reactions. Although the VP magnitude is largely determined by stimulus intensity, the relative contribution of the differential and absolute components of intensity remains unknown. Here, we dissociated the effects of these two components. We systematically varied the size of abrupt intensity increases embedded within continuous stimulation at different absolute intensities, while recording brain activity in humans (with scalp electroencephalography) and rats (with epidural electrocorticography). We obtained three main results. 1) VP magnitude largely depends on differential, and not absolute, stimulus intensity. This result held true, 2) for both auditory and somatosensory stimuli, indicating that sensitivity to differential intensity is supramodal, and 3) in both humans and rats, suggesting that sensitivity to abrupt intensity differentials is phylogenetically well-conserved. Altogether, the current results show that these large electrocortical responses are most sensitive to the detection of sensory changes that more likely signal the sudden appearance of novel objects or events in the environment.

Platelets, circulating tissue factor, and fibrin colocalize in ex vivo thrombi: real-time fluorescence images of thrombus formation and propagation under defined flow conditions

Blood ◽  
2002 ◽  
Vol 100 (8) ◽  
pp. 2787-2792 ◽  
Author(s):  
Viji Balasubramanian ◽  
Eric Grabowski ◽  
Alessandra Bini ◽  
Yale Nemerson
Keyword(s):  
Real Time ◽  
Tissue Factor ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
High Sensitivity ◽  
Flow Chamber ◽  
Flow Conditions ◽  
Coated Glass ◽  
Relative Contribution ◽  
Fluorescent Markers

Although it is generally accepted that the initial event in coagulation and intravascular thrombus formation is the exposure of tissue factor (TF) to blood, there is still little agreement about the mechanisms of thrombus propagation and the identities of the molecular species participating in this process. In this study, we characterized the thrombotic process in real-time and under defined flow conditions to determine the relative contribution and spatial distribution of 3 components of the thrombi: circulating or blood-borne TF (cTF), fibrin, and platelets. For this purpose, we used high-sensitivity, multicolor immunofluorescence microscopy coupled with a laminar flow chamber. Freshly drawn blood, labeled with mepacrine (marker for platelets and white cells), anti-hTF1Alexa.568 (marker for tissue factor), and anti-T2G1Cy­5 (marker for fibrin) was perfused over collagen-coated glass slides at wall shear rates of 100 and 650 s−1. A motorized filter cube selector facilitated imaging every 5 seconds at 1 of 3 different wavelengths, corresponding to optimal wavelengths for the 3 markers above. Real-time video recordings obtained during each of 10 discrete experiments show rapid deposition of platelets and fibrin onto collagen-coated glass. Overlay images of fluorescent markers corresponding to platelets, fibrin, and cTF clearly demonstrate colocalization of these 3 components in growing thrombi. These data further support our earlier observations that, in addition to TF present in the vessel wall, there is a pool of TF in circulating blood that contributes to the propagation of thrombosis at a site of vascular injury.

scholarly journals Recording brain activities in unshielded Earth’s field with optically pumped atomic magnetometers

2020 ◽  
Vol 6 (24) ◽  
pp. eaba8792 ◽  
Author(s):  
Rui Zhang ◽  
Wei Xiao ◽  
Yudong Ding ◽  
Yulong Feng ◽  
Xiang Peng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Medical Diagnosis ◽  
Alpha Rhythm ◽  
Brain Activity ◽  
High Sensitivity ◽  
Noninvasive Method ◽  
Optically Pumped ◽  
Field Noise ◽  
The Relationship ◽  
The Brain

Understanding the relationship between brain activity and specific mental function is important for medical diagnosis of brain symptoms, such as epilepsy. Magnetoencephalography (MEG), which uses an array of high-sensitivity magnetometers to record magnetic field signals generated from neural currents occurring naturally in the brain, is a noninvasive method for locating the brain activities. The MEG is normally performed in a magnetically shielded room. Here, we introduce an unshielded MEG system based on optically pumped atomic magnetometers. We build an atomic magnetic gradiometer, together with feedback methods, to reduce the environment magnetic field noise. We successfully observe the alpha rhythm signals related to closed eyes and clear auditory evoked field signals in unshielded Earth’s field. Combined with improvements in the miniaturization of the atomic magnetometer, our method is promising to realize a practical wearable and movable unshielded MEG system and bring new insights into medical diagnosis of brain symptoms.

Experience-dependent Plasticity of Conceptual Representations in Human Sensory-Motor Areas

2007 ◽  
Vol 19 (3) ◽  
pp. 525-542 ◽  
Author(s):  
Markus Kiefer ◽  
Eun-Jin Sim ◽  
Sarah Liebich ◽  
Olaf Hauk ◽  
James Tanaka
Keyword(s):  
Brain Activity ◽  
Learning Experience ◽  
Training Group ◽  
Conceptual Representations ◽  
Electrical Brain Activity ◽  
Sensory Motor ◽  
Novel Objects ◽  
Conceptual Memory ◽  
Specific Learning ◽  
Motor Areas

Concepts are composed of features related to different sensory and motor modalities such as vision, sound, and action. It is a matter of controversy whether conceptual features are represented in sensory-motor areas reflecting the specific learning experience during acquisition. In order to address this issue, we assessed the plasticity of conceptual representations by training human participants with novel objects under different training conditions. These objects were assigned to categories such that for one class of categories, the overall shape was diagnostic for category membership, whereas for the other class, a detail feature affording a particular action was diagnostic. During training, participants were asked to either make an action pantomime toward the detail feature of the novel object or point to it. In a categorization task at test, we assessed the neural correlates of the acquired conceptual representations by measuring electrical brain activity. Here, we show that the same object is differentially processed depending on the sensory-motor interactions during knowledge acquisition. Only in the pantomime group did we find early activation in frontal motor regions and later activation in occipito-parietal visual-motor regions. In the pointing training group, these effects were absent. These results show that action information contributes to conceptual processing depending on the specific learning experience. In line with modality-specific theories of conceptual memory, our study suggests that conceptual representations are established by the learning-based formation of cell assemblies in sensory-motor areas.

scholarly journals Emerging imaging methods to study whole-brain function in rodent models

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marija Markicevic ◽  
Iurii Savvateev ◽  
Christina Grimm ◽  
Valerio Zerbi
Keyword(s):  
Large Scale ◽  
Functional Organization ◽  
Imaging Techniques ◽  
Brain Activity ◽  
Research Question ◽  
Careful Consideration ◽  
Mammalian Brain ◽  
High Temporal Resolution ◽  
Imaging Methods ◽  
Evoked Activity

AbstractIn the past decade, the idea that single populations of neurons support cognition and behavior has gradually given way to the realization that connectivity matters and that complex behavior results from interactions between remote yet anatomically connected areas that form specialized networks. In parallel, innovation in brain imaging techniques has led to the availability of a broad set of imaging tools to characterize the functional organization of complex networks. However, each of these tools poses significant technical challenges and faces limitations, which require careful consideration of their underlying anatomical, physiological, and physical specificity. In this review, we focus on emerging methods for measuring spontaneous or evoked activity in the brain. We discuss methods that can measure large-scale brain activity (directly or indirectly) with a relatively high temporal resolution, from milliseconds to seconds. We further focus on methods designed for studying the mammalian brain in preclinical models, specifically in mice and rats. This field has seen a great deal of innovation in recent years, facilitated by concomitant innovation in gene-editing techniques and the possibility of more invasive recordings. This review aims to give an overview of currently available preclinical imaging methods and an outlook on future developments. This information is suitable for educational purposes and for assisting scientists in choosing the appropriate method for their own research question.

scholarly journals Hippocampal-like network dynamics underlie avian sharp wave-ripples

2019 ◽  
Author(s):  
Hamed Yeganegi ◽  
Harald Luksch ◽  
Janie M. Ondracek
Keyword(s):  
Brain Activity ◽  
Mammalian Species ◽  
High Frequency Oscillation ◽  
Mammalian Brain ◽  
Dynamic Switching ◽  
Sharp Wave ◽  
Sharp Waves ◽  
Electrophysiological Recordings ◽  
Spike Analysis ◽  
Spiking Activity

Sharp wave ripples (SWR) represent one of the most synchronous population patterns in the mammalian brain. Although SWRs are highly conserved throughout mammalian evolution, the existence of SWRs in non-mammalian species remains controversial. We reexamined the existence of avian SWRs by recording the brain activity during sleep and under anesthesia in two species of birds, the zebra finch and the chicken. Electrophysiological recordings using silicon probes implanted in the avian telencephalon revealed highly dynamic switching between high and low delta phases during sleep. High delta phases were composed of large-amplitude, negative deflections (sharp waves) that coincided with a high frequency oscillation (ripple). Correlation analysis revealed that these events were highly synchronous and spanned a large anatomical range of the avian telencephalon. Finally, detailed spike analysis revealed that an increase in the population spiking activity coincided with the occurrence of SWRs, that this spiking activity occurred in specific sequences of spike patterns locked to the SWRs, and that the mean population spiking activity peaked prior to the trough of the negative deflection. These results provide the first evidence of avian SWRs during natural sleep and under anesthesia, and suggest that the evolutionary origin of SWR activity may precede the mammalian-sauropsid bifurcation.

scholarly journals Metabolism modulates network synchrony in the aging brain

2020 ◽  
Author(s):  
Corey Weistuch ◽  
Lilianne R Mujica-Parodi ◽  
Anar Amgalan ◽  
Ken A Dill
Keyword(s):  
Statistical Physics ◽  
Quantitative Methods ◽  
Brain Aging ◽  
Brain Activity ◽  
High Sensitivity ◽  
Brain Regions ◽  
Aging Brain ◽  
Global Changes ◽  
Abrupt Changes ◽  
Network Synchrony

AbstractBrain aging is associated with hypometabolism and associated global changes in functional connectivity. Using fMRI, we show that network synchrony, a collective property of brain activity, decreases with age. Applying quantitative methods from statistical physics, we provide a generative (Ising) model for these changes as a function of the average communication strength between brain regions. In particular, we find healthy brains to be poised at a critical point of this communication strength, enabling a balance between segregated (to functional domains) and integrated (between domains) patterns of synchrony. However, one characteristic of criticality is a high sensitivity to small changes. Thus, minute weakening of pairwise communication between regions, as seen in the aging brain, gives rise to qualitatively abrupt changes in synchrony. Finally, by experimentally modulating metabolic activity in younger adults, we show how metabolism alone–independent of other changes associated with aging–can provide a mechanism for global changes in synchrony.

scholarly journals Parental prey selection affects risk-taking behaviour and spatial learning in avian offspring

2007 ◽  
Vol 274 (1625) ◽  
pp. 2563-2569 ◽  
Author(s):  
Kathryn E Arnold ◽  
Scot L Ramsay ◽  
Christine Donaldson ◽  
Aileen Adam
Keyword(s):  
Spatial Learning ◽  
Risk Taking ◽  
Prey Selection ◽  
Learning Task ◽  
Control Treatment ◽  
Mammalian Brain ◽  
Mammalian Development ◽  
Cyanistes Caeruleus ◽  
Novel Objects ◽  
Spatial Learning Task

Early nutrition shapes life history. Parents should, therefore, provide a diet that will optimize the nutrient intake of their offspring. In a number of passerines, there is an often observed, but unexplained, peak in spider provisioning during chick development. We show that the proportion of spiders in the diet of nestling blue tits, Cyanistes caeruleus , varies significantly with the age of chicks but is unrelated to the timing of breeding or spider availability. Moreover, this parental prey selection supplies nestlings with high levels of taurine particularly at younger ages. This amino acid is known to be both vital and limiting for mammalian development and consequently found in high concentrations in placenta and milk. Based on the known roles of taurine in mammalian brain development and function, we then asked whether by supplying taurine-rich spiders, avian parents influence the stress responsiveness and cognitive function of their offspring. To test this, we provided wild blue tit nestlings with either a taurine supplement or control treatment once daily from the ages of 2–14 days. Then pairs of size- and sex-matched siblings were brought into captivity for behavioural testing. We found that juveniles that had received additional taurine as neonates took significantly greater risks when investigating novel objects than controls. Taurine birds were also more successful at a spatial learning task than controls. Additionally, those individuals that succeeded at a spatial learning task had shown intermediate levels of risk taking. Non-learners were generally very risk-averse controls. Early diet therefore has downstream impacts on behavioural characteristics that could affect fitness via foraging and competitive performance. Fine-scale prey selection is a mechanism by which parents can manipulate the behavioural phenotype of offspring.

scholarly journals Temporal transitions of spontaneous brain activity

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Zhiwei Ma ◽  
Nanyin Zhang
Keyword(s):  
Graph Theory ◽  
Resting State ◽  
Temporal Relationship ◽  
Brain Activity ◽  
Resting State Fmri ◽  
Temporal Organization ◽  
Mammalian Brain ◽  
Resting State Functional Connectivity ◽  
Spontaneous Brain Activity ◽  
Awake Rats

Spontaneous brain activity, typically investigated using resting-state fMRI (rsfMRI), provides a measure of inter-areal resting-state functional connectivity (RSFC). Although it has been established that RSFC is non-stationary, previous dynamic rsfMRI studies mainly focused on revealing the spatial characteristics of dynamic RSFC patterns, but the temporal relationship between these RSFC patterns remains elusive. Here we investigated the temporal organization of characteristic RSFC patterns in awake rats and humans. We found that transitions between RSFC patterns were not random but followed specific sequential orders. The organization of RSFC pattern transitions was further analyzed using graph theory, and pivotal RSFC patterns in transitions were identified. This study has demonstrated that spontaneous brain activity is not only nonrandom spatially, but also nonrandom temporally, and this feature is well conserved between rodents and humans. These results offer new insights into understanding the spatiotemporal dynamics of spontaneous activity in the mammalian brain.

scholarly journals Brain activity mapping at multiple scales with silicon microprobes containing 1,024 electrodes

2015 ◽  
Vol 114 (3) ◽  
pp. 2043-2052 ◽  
Author(s):  
Justin L. Shobe ◽  
Leslie D. Claar ◽  
Sepideh Parhami ◽  
Konstantin I. Bakhurin ◽  
Sotiris C. Masmanidis
Keyword(s):  
Multiple Scales ◽  
Functional Organization ◽  
Brain Activity ◽  
Three Dimensional ◽  
Field Potential ◽  
Neural Systems ◽  
Mammalian Brain ◽  
Neural Signals ◽  
Neural Ensembles ◽  
Potential Activity

The coordinated activity of neural ensembles across multiple interconnected regions has been challenging to study in the mammalian brain with cellular resolution using conventional recording tools. For instance, neural systems regulating learned behaviors often encompass multiple distinct structures that span the brain. To address this challenge we developed a three-dimensional (3D) silicon microprobe capable of simultaneously measuring extracellular spike and local field potential activity from 1,024 electrodes. The microprobe geometry can be precisely configured during assembly to target virtually any combination of four spatially distinct neuroanatomical planes. Here we report on the operation of such a device built for high-throughput monitoring of neural signals in the orbitofrontal cortex and several nuclei in the basal ganglia. We perform analysis on systems-level dynamics and correlations during periods of conditioned behavioral responding and rest, demonstrating the technology's ability to reveal functional organization at multiple scales in parallel in the mouse brain.

scholarly journals Neuroaging through the Lens of the Resting State Networks

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Filippo Cieri ◽  
Roberto Esposito
Keyword(s):  
Resting State ◽  
Brain Activity ◽  
High Sensitivity ◽  
Clinical Findings ◽  
Blood Oxygenation ◽  
Resting State Networks ◽  
Late Life Depression ◽  
Alzheimer Dementia ◽  
Structural Modifications ◽  
Oxygenation Level

Resting state functional magnetic resonance imaging (rs-fMRI) allows studying spontaneous brain activity in absence of task, recording changes of Blood Oxygenation Level Dependent (BOLD) signal. rs-fMRI enables identification of brain networks also called Resting State Networks (RSNs) including the most studied Default Mode Network (DMN). The simplicity and speed of execution make rs-fMRI applicable in a variety of normal and pathological conditions. Since it does not require any task, rs-fMRI is particularly useful for protocols on patients, children, and elders, increasing participant’s compliance and reducing intersubjective variability due to the task performance. rs-fMRI has shown high sensitivity in identification of RSNs modifications in several diseases also in absence of structural modifications. In this narrative review, we provide the state of the art of rs-fMRI studies about physiological and pathological aging processes. First, we introduce the background of resting state; then we review clinical findings provided by rs-fMRI in physiological aging, Mild Cognitive Impairment (MCI), Alzheimer Dementia (AD), and Late Life Depression (LLD). Finally, we suggest future directions in this field of research and its potential clinical applications.

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