Regionalisation of the callosal contribution to the barrel field activity in the mouse

Synchrony of neural activity among cortical areas arises from functional coupling between those areas. Such a strong synchrony characterises the two mouse barrel fields (BFs) when the animal is deeply anaesthetised or asleep. In these conditions, neurons in the two hemispheres depolarise (up-state) and hyperpolarise to their resting potential (down-state) in a remarkably coordinated fashion. Callosal glutamatergic axons provide a means to functionally couple supra- and infragranular neurons of the two BFs. However, little is known about their relationship with the BF grid-like architecture: Are they able to influence the activity of barrel and/or septal neurons? Are there specific barrels more sensitive to the contralateral activity? To respond to these questions, we localised and counted the BF cells positive to c-Fos (c-Fos + ) resulting from a contralateral whiskers deprivation when mice were free to explore a novel environment. In layer 4, we found a greater number of c-Fos + cells in septa compared to barrels, which mainly localised in the posterior and lateral aspects of the sensory-deprived BF. To learn more about such interhemispheric recruitment, we studied the propagation of slow-oscillatory activity in anaesthetised mice. We performed whole-cell patch-clamp in the ipsilateral BF while recording LFPs in the contralateral BF. In the BF lateral region, neurons showed faster oscillatory cycles, shorter up-state duration and faster down-to-up transitions compared to neurons recorded in BF regions with a sparser c-Fos signal, suggesting the reception of extra inputs in the former. We thus propose that the lateral BF is a critical sub-region for BFs activity-coupling.

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Functional synchronization between hippocampal sEEG, parietal ECoG and scalp EEG during a verbal working memory task

10.1101/2020.06.05.136515 ◽

2020 ◽

Author(s):

Vasileios Dimakopoulos ◽

Ece Boran ◽

Peter Hilfiker ◽

Lennart Stieglitz ◽

Thomas Grunwald ◽

...

Keyword(s):

Working Memory ◽

Auditory Cortex ◽

Information Flow ◽

Verbal Working Memory ◽

Oscillatory Activity ◽

Functional Coupling ◽

Maintenance Period ◽

Physiological Basis ◽

Cortical Areas ◽

Scalp Eeg

ABSTRACTBackgroundThe maintenance of items in working memory (WM) relies on a widespread network of brain areas where synchronization between electrophysiological recordings may reflect functional coupling. While the coupling from hippocampus to scalp EEG is well established, we provide here direct cortical recordings for a fine-grained analysis.MethodsA patient performed a WM task where a string of letters was presented all at once, thus separating the encoding period from the maintenance period. We recorded sEEG from the hippocampus, temporo-parietal ECoG from a 64-contact grid electrode, and scalp EEG.ResultsPower spectral density (PSD) showed a clear task dependence: PSD in the posterior parietal lobe (10 Hz) and in the hippocampus (20 Hz) peaked towards the end of the maintenance period.Inter-area synchronization was characterized by the phase locking value (PLV). WM maintenance enhanced PLV between hippocampal sEEG and scalp EEG specifically in the theta range [6 7] Hz.PLV from hippocampus to parietal cortex increased during maintenance in the [9 10] Hz alpha and the 20 Hz range.When analyzing the information flow to and from auditory cortex by Granger causality, the flow was from auditory cortex to hippocampus with a peak in the [8 18] Hz range while letters were presented, and this flow was subsequently reversed during maintenance, while letters were maintained in memory.ConclusionsThe increased functional interaction between hippocampus and cortex through synchronized oscillatory activity and the directed information flow provide physiological basis for reverberation of memory items during maintenance. This points to a network for working memory that is bound by coherent oscillations involving cortical areas and hippocampus.SIGNIFICANCE STATEMENTHippocampal activity is known for its role in cognitive tasks involving episodic memory or spatial navigation, but its role in working memory and its sensitivity to workload is still under debate. Here, we investigated hippocampal and cortical activity while a subject maintained sets of letters in verbal working memory for a few seconds to guide action.After confirming the coupling between hippocampal oscillations and oscillations on the scalp, we found during maintenance that hippocampal oscillations increased coupling differentially to several areas of cortex by recording directly from the cortex.. During encoding of the letters, information flow was from auditory cortex to hippocampus and subsequently reversed during maintenance, thus providing a physiological basis for memory encoding and maintenance.This demonstrates a network for working memory that is bound by coherent oscillations that underlie the functional connectivity between cortical areas and hippocampus.

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An Extrasynaptic GABAA Receptor Mediates Tonic Inhibition in Thalamic VB Neurons

Journal of Neurophysiology ◽

10.1152/jn.00421.2005 ◽

2005 ◽

Vol 94 (6) ◽

pp. 4491-4501 ◽

Cited By ~ 168

Author(s):

Fan Jia ◽

Leonardo Pignataro ◽

Claude M. Schofield ◽

Minerva Yue ◽

Neil L. Harrison ◽

...

Keyword(s):

Critical Role ◽

Brain Slices ◽

Oscillatory Activity ◽

Thalamic Neurons ◽

Hek 293 ◽

Subunit Protein ◽

Whole Cell Patch Clamp ◽

293 Cells ◽

Hypnotic Agent ◽

Tonic Current

Whole cell patch-clamp recordings were obtained from thalamic ventrobasal (VB) and reticular (RTN) neurons in mouse brain slices. A bicuculline-sensitive tonic current was observed in VB, but not in RTN, neurons; this current was increased by the GABAA receptor agonist 4,5,6,7-tetrahydroisothiazolo-[5,4-c]pyridine-3-ol (THIP; 0.1 μM) and decreased by Zn2+ (50 μM) but was unaffected by zolpidem (0.3 μM) or midazolam (0.2 μM). The pharmacological profile of the tonic current is consistent with its generation by activation of GABAA receptors that do not contain the α1 or γ2 subunits. GABAA receptors expressed in HEK 293 cells that contained α4β2δ subunits showed higher sensitivity to THIP (gaboxadol) and GABA than did receptors made up from α1β2δ, α4β2γ2s, or α1β2γ2s subunits. Western blot analysis revealed that there is little, if any, α3 or α5 subunit protein in VB. In addition, co-immunoprecipitation studies showed that antibodies to the δ subunit could precipitate α4, but not α1 subunit protein. Confocal microscopy of thalamic neurons grown in culture confirmed that α4 and δ subunits are extensively co-localized with one another and are found predominantly, but not exclusively, at extrasynaptic sites. We conclude that thalamic VB neurons express extrasynaptic GABAA receptors that are highly sensitive to GABA and THIP and that these receptors are most likely made up of α4β2δ subunits. In view of the critical role of thalamic neurons in the generation of oscillatory activity associated with sleep, these receptors may represent a principal site of action for the novel hypnotic agent gaboxadol.

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Olfaction Modulates Early Neural Responses to Matching Visual Objects

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00732 ◽

2015 ◽

Vol 27 (4) ◽

pp. 832-841 ◽

Cited By ~ 11

Author(s):

Amanda K. Robinson ◽

Judith Reinhard ◽

Jason B. Mattingley

Keyword(s):

Neural Activity ◽

Visual Processing ◽

Sensory Information ◽

Neural Correlates ◽

Neural Responses ◽

Visual Objects ◽

Cortical Areas ◽

Early Visual Processing ◽

Considerable Research ◽

Matter Concentration

Sensory information is initially registered within anatomically and functionally segregated brain networks but is also integrated across modalities in higher cortical areas. Although considerable research has focused on uncovering the neural correlates of multisensory integration for the modalities of vision, audition, and touch, much less attention has been devoted to understanding interactions between vision and olfaction in humans. In this study, we asked how odors affect neural activity evoked by images of familiar visual objects associated with characteristic smells. We employed scalp-recorded EEG to measure visual ERPs evoked by briefly presented pictures of familiar objects, such as an orange, mint leaves, or a rose. During presentation of each visual stimulus, participants inhaled either a matching odor, a nonmatching odor, or plain air. The N1 component of the visual ERP was significantly enhanced for matching odors in women, but not in men. This is consistent with evidence that women are superior in detecting, discriminating, and identifying odors and that they have a higher gray matter concentration in olfactory areas of the OFC. We conclude that early visual processing is influenced by olfactory cues because of associations between odors and the objects that emit them, and that these associations are stronger in women than in men.

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Routing information flow by separate neural synchrony frequencies allows for “functionally labeled lines” in higher primate cortex

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1819827116 ◽

2019 ◽

Vol 116 (25) ◽

pp. 12506-12515 ◽

Cited By ~ 14

Author(s):

Mohammad Bagher Khamechian ◽

Vladislav Kozyrev ◽

Stefan Treue ◽

Moein Esghaei ◽

Mohammad Reza Daliri

Keyword(s):

Information Flow ◽

Information Transfer ◽

Sensory Information ◽

Spike Timing ◽

Oscillatory Activity ◽

Attention Task ◽

Cortical Areas ◽

High Gamma ◽

Ventral Pathway ◽

Visual Cortical

Efficient transfer of sensory information to higher (motor or associative) areas in primate visual cortical areas is crucial for transforming sensory input into behavioral actions. Dynamically increasing the level of coordination between single neurons has been suggested as an important contributor to this efficiency. We propose that differences between the functional coordination in different visual pathways might be used to unambiguously identify the source of input to the higher areas, ensuring a proper routing of the information flow. Here we determined the level of coordination between neurons in area MT in macaque visual cortex in a visual attention task via the strength of synchronization between the neurons’ spike timing relative to the phase of oscillatory activities in local field potentials. In contrast to reports on the ventral visual pathway, we observed the synchrony of spikes only in the range of high gamma (180 to 220 Hz), rather than gamma (40 to 70 Hz) (as reported previously) to predict the animal’s reaction speed. This supports a mechanistic role of the phase of high-gamma oscillatory activity in dynamically modulating the efficiency of neuronal information transfer. In addition, for inputs to higher cortical areas converging from the dorsal and ventral pathway, the distinct frequency bands of these inputs can be leveraged to preserve the identity of the input source. In this way source-specific oscillatory activity in primate cortex can serve to establish and maintain “functionally labeled lines” for dynamically adjusting cortical information transfer and multiplexing converging sensory signals.

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Layer 4 organization and respiration locking in the rodent nose somatosensory cortex

Journal of Neurophysiology ◽

10.1152/jn.00138.2020 ◽

2020 ◽

Vol 124 (3) ◽

pp. 822-832 ◽

Cited By ~ 1

Author(s):

Eduard Maier ◽

Simon Lauer ◽

Michael Brecht

Keyword(s):

Somatosensory Cortex ◽

Neural Activity ◽

Field Recordings ◽

Physiological Properties ◽

Sensory Modalities ◽

Layer 4

We characterized the rodent nose somatosensory cortex. The nostril representation appeared as a kind of “hole” (i.e., as a stripe-like recess of layer 4) in tangential cortical sections. Neural activity in nose somatosensory cortex was locked to respiration and simultaneous field recordings indicate that this locking was specific to this region. Our results reveal previously unknown cytoarchitectonic and physiological properties of the rodent nose somatosensory cortex, potentially enabling it to integrate multiple sensory modalities.

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Cx46 hemichannels contribute to the sodium leak conductance in lens fiber cells

AJP Cell Physiology ◽

10.1152/ajpcell.00353.2013 ◽

2014 ◽

Vol 306 (5) ◽

pp. C506-C513 ◽

Cited By ~ 9

Author(s):

Lisa Ebihara ◽

Yegor Korzyukov ◽

Sorabh Kothari ◽

Jun-Jie Tong

Keyword(s):

Open Channel ◽

Basal Membrane ◽

Resting Potential ◽

Channel Noise ◽

Lens Fiber ◽

Patch Clamp Technique ◽

Fiber Cells ◽

Whole Cell Patch Clamp ◽

Ionic Fluxes ◽

Persistent Inward Current

The lens is proposed to have an internal microcirculation system consisting of continuously circulating ionic fluxes that play an essential role in maintaining lens transparency. One of the key components of this system is the sodium leak conductance. Here we investigate the contribution of Cx46 hemichannels to the basal membrane permeability of peripheral fiber cells isolated from transgenic mouse lenses lacking Cx50 or both Cx50 and Cx46 (dKO) using the whole cell patch-clamp technique. Our results show that Cx46 hemichannels were largely closed at a resting voltage of −60 mV in the presence of millimolar divalent cation concentrations. However, even though the vast majority of these channels were closed at −60 mV, a small, persistent, inward current could still be detected. This current could be mostly blocked by exposure to 1 mM La3+ and was not observed in fiber cells isolated from dKO mouse lenses suggesting that it was due to Cx46 hemichannels. In addition, Cx50−/− fiber cells showed increased open channel noise and a depolarized resting potential compared with dKO fiber cells. Exposure of Cx50−/− fiber cells to La3+ hyperpolarized the resting potential to −58 mV, which is similar to the value of resting potential measured in dKO fiber and significantly reduced the open channel noise. In conclusion, these results suggest that Cx46 hemichannels may contribute to the sodium leak conductance in lens fiber cells.

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A NEUROBIOLOGICAL THEORY OF MEANING IN PERCEPTION PART III: MULTIPLE CORTICAL AREAS SYNCHRONIZE WITHOUT LOSS OF LOCAL AUTONOMY

International Journal of Bifurcation and Chaos ◽

10.1142/s0218127403008260 ◽

2003 ◽

Vol 13 (10) ◽

pp. 2845-2856 ◽

Cited By ~ 38

Author(s):

WALTER J. FREEMAN ◽

GYöNGYI GAÁL ◽

REBECKA JORSTEN

Keyword(s):

Information Transfer ◽

Phase Locking ◽

Pulse Frequency ◽

Inhibitory Neurons ◽

Oscillatory Activity ◽

Electrode Arrays ◽

Ensemble Averaging ◽

Pulse Frequency Modulation ◽

Cortical Areas ◽

Gamma Range

Information transfer and integration among functionally distinct areas of cerebral cortex of oscillatory activity require some degree of phase synchrony of the trains of action potentials that carry the information prior to the integration. However, propagation delays are obligatory. Delays vary with the lengths and conduction velocities of the axons carrying the information, causing phase dispersion. In order to determine how synchrony is achieved despite dispersion, we recorded EEG signals from multiple electrode arrays on five cortical areas in cats and rabbits, that had been trained to discriminate visual or auditory conditioned stimuli. Analysis by time-lagged correlation, multiple correlation and PCA, showed that maximal correlation was at zero lag and averaged 0.7, indicating that 50% of the power in the gamma range among the five areas was at zero lag irrespective of phase or frequency. There were no stimulus-related episodes of transiently increased phase locking among the areas, nor EEG "bursts" of transiently increased amplitude above the sustained level of synchrony. Three operations were identified to account for the sustained correlation. Cortices broadcast their outputs over divergent–convergent axonal pathways that performed spatial ensemble averaging; synaptic interactions between excitatory and inhibitory neurons in cortex operated as band pass filters for gamma; and signal coarse-graining by pulse frequency modulation at trigger zones enhanced correlation. The conclusion is that these three operations enable continuous linkage of multiple cortical areas by activity in the gamma range, providing the basis for coordinated cortical output to other parts of the brain, despite varying axonal conduction delays, something like the back plane of a main frame computer.

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Cre recombinase-mediated gene deletion in layer 4 of murine sensory cortical areas

genesis ◽

10.1002/dvg.20393 ◽

2008 ◽

Vol 46 (6) ◽

pp. 289-293 ◽

Cited By ~ 9

Author(s):

Guey-Ying Liao ◽

Baoji Xu

Keyword(s):

Gene Deletion ◽

Cre Recombinase ◽

Cortical Areas ◽

Layer 4

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Brain Frequency-Specific Changes in the Spontaneous Neural Activity Are Associated With Cognitive Impairment in Patients With Presbycusis

Frontiers in Aging Neuroscience ◽

10.3389/fnagi.2021.649874 ◽

2021 ◽

Vol 13 ◽

Author(s):

Fuxin Ren ◽

Wen Ma ◽

Wei Zong ◽

Ning Li ◽

Xiao Li ◽

...

Keyword(s):

Cognitive Impairment ◽

Auditory Cortex ◽

Neural Activity ◽

Auditory Processing ◽

Low Frequency ◽

Frontal Eye Field ◽

Functional Coupling ◽

Frequency Bands ◽

Spontaneous Neural Activity ◽

Key Nodes

Presbycusis (PC) is characterized by preferential hearing loss at high frequencies and difficulty in speech recognition in noisy environments. Previous studies have linked PC to cognitive impairment, accelerated cognitive decline and incident Alzheimer’s disease. However, the neural mechanisms of cognitive impairment in patients with PC remain unclear. Although resting-state functional magnetic resonance imaging (rs-fMRI) studies have explored low-frequency oscillation (LFO) connectivity or amplitude of PC-related neural activity, it remains unclear whether the abnormalities occur within all frequency bands or within specific frequency bands. Fifty-one PC patients and fifty-one well-matched normal hearing controls participated in this study. The LFO amplitudes were investigated using the amplitude of low-frequency fluctuation (ALFF) at different frequency bands (slow-4 and slow-5). PC patients showed abnormal LFO amplitudes in the Heschl’s gyrus, dorsolateral prefrontal cortex (dlPFC), frontal eye field and key nodes of the speech network exclusively in slow-4, which suggested that abnormal spontaneous neural activity in PC was frequency dependent. Our findings also revealed that stronger functional connectivity between the dlPFC and the posterodorsal stream of auditory processing, as well as lower functional coupling between the PCC and key nodes of the DMN, which were associated with cognitive impairments in PC patients. Our study might underlie the cross-modal plasticity and higher-order cognitive participation of the auditory cortex after partial hearing deprivation. Our findings indicate that frequency-specific analysis of ALFF could provide valuable insights into functional alterations in the auditory cortex and non-auditory regions involved in cognitive impairment associated with PC.

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Cognitive experience alters cortical involvement in navigation decisions

10.1101/2021.12.10.472106 ◽

2021 ◽

Author(s):

Christopher D Harvey ◽

Charlotte Arlt ◽

Roberto Barroso-Luque ◽

Shinichiro Kira ◽

Carissa A Bruno ◽

...

Keyword(s):

Decision Making ◽

Neural Activity ◽

Calcium Imaging ◽

Posterior Parietal Cortex ◽

Retrosplenial Cortex ◽

Neuron Activity ◽

Decision Task ◽

Simple Task ◽

Critical Determinant ◽

Cortical Areas

The neural correlates of decision-making have been investigated extensively, and recent work aims to identify under what conditions cortex is actually necessary for making accurate decisions. We discovered that mice with distinct cognitive experiences, beyond sensory and motor learning, use different cortical areas and neural activity patterns to solve the same task, revealing past learning as a critical determinant of whether cortex is necessary for decision-making. We used optogenetics and calcium imaging to study the necessity and neural activity of multiple cortical areas in mice with different training histories. Posterior parietal cortex and retrosplenial cortex were mostly dispensable for accurate decision-making in mice performing a simple navigation-based decision task. In contrast, these areas were essential for the same simple task when mice were previously trained on complex tasks with delay periods or association switches. Multi-area calcium imaging showed that, in mice with complex-task experience, single-neuron activity had higher selectivity and neuron-neuron correlations were weaker, leading to codes with higher task information. Therefore, past experience sets the landscape for how future tasks are solved by the brain and is a key factor in determining whether cortical areas have a causal role in decision-making.

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