scholarly journals Piriform cortex provides a dominant gamma LFP oscillation in the anterior limbic system

2019 ◽  
Author(s):  
James E. Carmichael ◽  
Matthew M. Yuen ◽  
Matthijs A. A. van der Meer
Keyword(s):  
Limbic System ◽  
Piriform Cortex ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Brain Regions ◽  
Gamma Band ◽  
Male Rats ◽  
Major Influence ◽  
Cortex Cell

AbstractOscillations in the local field potential (LFP) are widespread throughout the rodent limbic system, including in structures such as the orbitofrontal cortex and nucleus accumbens. Synchrony between LFPs across these structures, as seen during specific behavioral events, is often interpreted as evidence of a functional interaction. However, the source of these oscillations is often tacitly assumed to be local, leading to a potential misattribution of function. Using in vivo simultaneous multisite recordings in freely moving male rats (n = 7) we demonstrate that gamma-band LFP oscillations (45-90 Hz) in multiple anterior limbic structures are highly synchronous not only with each other, but also with those in piriform cortex. Phase reversals across the piriform cortex cell layer and susceptibility to nasal occlusion indicate that piriform cortex is the source of these common gamma oscillations. Thus, gamma-band LFP oscillations seen in brain regions adjacent to the piriform cortex are likely not generated locally, but are instead volume conducted from the piriform cortex. This emerging view of gamma oscillations in anterior limbic circuits highlights the importance of the common piriform cortex input as a major influence and introduces caveats in the interpretation of locally recorded LFPs.

scholarly journals Gamma oscillations in the rat ventral striatum originate in the piriform cortex

2017 ◽  
Author(s):  
James E. Carmichael ◽  
Jimmie M. Gmaz ◽  
Matthijs A. A. van der Meer
Keyword(s):  
Local Field ◽  
Ventral Striatum ◽  
Piriform Cortex ◽  
Current Source ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Gamma Band ◽  
Temporal Organization ◽  
Local Circuitry ◽  
Gamma Band Oscillations

AbstractLocal field potentials (LFP) recorded from the human and rodent ventral striatum (vStr) exhibit prominent, behaviorally relevant gamma-band oscillations. These oscillations are related to local spiking activity and transiently synchronize with anatomically related areas, suggesting a possible role in organizing vStr activity. However, the origin of vStr gamma is unknown. We recorded vStr gamma oscillations across a 1.4mm2 grid spanned by 64 recording electrodes as rats rested and foraged for rewards, revealing a highly consistent power gradient originating in the adjacent piriform cortex. Phase differences across the vStr were consistently small (<10°) and current source density analysis further confirmed the absence of local sink-source pairs in the vStr. Reversible occlusions of the ipsilateral (but not contralateral) nostril, known to abolish gamma oscillations in the piriform cortex, strongly reduced vStr gamma power and the occurrence of transient gamma-band events. These results imply that local circuitry is not a major contributor to gamma oscillations in the vStr LFP, and that piriform cortex is an important driver of gamma-band oscillations in the vStr and associated limbic areas.Significance StatementThe ventral striatum is an area of anatomical convergence in circuits underlying motivated behavior, but it remains unclear how its inputs from different sources interact. One of the major proposals of how neural circuits may dynamically switch between convergent inputs is through temporal organization reflected in local field potential (LFP) oscillations. Our results show that in the rat, the mechanisms controlling vStr gamma oscillations are primarily located in the in the adjacent piriform cortex, rather than vStr itself. This provides a novel interpretation of previous rodent work on gamma oscillations in the vStr and related circuits, and an important consideration for future work seeking to use oscillations in these areas as biomarkers in rodent models of human behavioral and neurological disorders.

scholarly journals A neural circuit for gamma-band coherence across the retinotopic map in mouse visual cortex

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Richard Hakim ◽  
Kiarash Shamardani ◽  
Hillel Adesnik
Keyword(s):  
Visual Cortex ◽  
Neural Circuit ◽  
Brain Slices ◽  
Pyramidal Cells ◽  
Gamma Oscillations ◽  
Gamma Band ◽  
Neuron Activity ◽  
Mouse Visual Cortex ◽  
Retinotopic Map

Cortical gamma oscillations have been implicated in a variety of cognitive, behavioral, and circuit-level phenomena. However, the circuit mechanisms of gamma-band generation and synchronization across cortical space remain uncertain. Using optogenetic patterned illumination in acute brain slices of mouse visual cortex, we define a circuit composed of layer 2/3 (L2/3) pyramidal cells and somatostatin (SOM) interneurons that phase-locks ensembles across the retinotopic map. The network oscillations generated here emerge from non-periodic stimuli, and are stimulus size-dependent, coherent across cortical space, narrow band (30 Hz), and depend on SOM neuron but not parvalbumin (PV) neuron activity; similar to visually induced gamma oscillations observed in vivo. Gamma oscillations generated in separate cortical locations exhibited high coherence as far apart as 850 μm, and lateral gamma entrainment depended on SOM neuron activity. These data identify a circuit that is sufficient to mediate long-range gamma-band coherence in the primary visual cortex.

Stimulation of the Parasubiculum Modulates Entorhinal Cortex Responses to Piriform Cortex Inputs In Vivo

2004 ◽  
Vol 92 (2) ◽  
pp. 1226-1235 ◽  
Author(s):  
Douglas A. Caruana ◽  
C. Andrew Chapman
Keyword(s):  
Entorhinal Cortex ◽  
Hippocampal Formation ◽  
Piriform Cortex ◽  
Current Source ◽  
Field Potential ◽  
Implanted Electrodes ◽  
Deep Layers ◽  
Negative Field ◽  
Stimulation Of

Although a major output of the hippocampal formation is from the subiculum to the deep layers of the entorhinal cortex, the parasubiculum projects to the superficial layers of the entorhinal cortex and may therefore modulate how the entorhinal cortex responds to sensory inputs from other cortical regions. Recordings at multiple depths in the entorhinal cortex were first used to characterize field potentials evoked by stimulation of the parasubiculum in urethan-anesthetized rats. Current source density analysis showed that a prominent surface-negative field potential component is generated by synaptic activation in layer II. The surface-negative field potential was also observed in rats with chronically implanted electrodes. The response was maintained during short stimulation trains of ≤125 Hz, suggesting that it is generated by activation of monosynaptic inputs to the entorhinal cortex. The piriform cortex also projects to layer II of the entorhinal cortex, and interactions between parasubicular and piriform cortex inputs were investigated using double-site stimulation tests. Simultaneous activation of parasubicular and piriform cortex inputs with high-intensity pulses resulted in smaller synaptic potentials than were expected on the basis of summing the individual responses, consistent with the termination of both pathways onto a common population of neurons. Paired-pulse tests were then used to assess the effect of parasubicular stimulation on responses to piriform cortex stimulation. Responses of the entorhinal cortex to piriform cortex inputs were inhibited when the parasubiculum was stimulated 5 ms earlier and were enhanced when the parasubiculum was stimulated 20–150 ms earlier. These results indicate that excitatory inputs to the entorhinal cortex from the parasubiculum may enhance the propagation of neuronal activation patterns into the hippocampal circuit by increasing the responsiveness of the entorhinal cortex to appropriately timed inputs.

scholarly journals Space coding by gamma oscillations in the barn owl optic tectum

2011 ◽  
Vol 105 (5) ◽  
pp. 2005-2017 ◽  
Author(s):  
Devarajan Sridharan ◽  
Kwabena Boahen ◽  
Eric I. Knudsen
Keyword(s):  
Optic Tectum ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Stimulus Location ◽  
Gamma Band ◽  
Sensory Stimuli ◽  
Visual Contrast ◽  
Wide Range ◽  
Gamma Power ◽  
Deep Layers

Gamma-band (25–140 Hz) oscillations of the local field potential (LFP) are evoked by sensory stimuli in the mammalian forebrain and may be strongly modulated in amplitude when animals attend to these stimuli. The optic tectum (OT) is a midbrain structure known to contribute to multimodal sensory processing, gaze control, and attention. We found that presentation of spatially localized stimuli, either visual or auditory, evoked robust gamma oscillations with distinctive properties in the superficial (visual) layers and in the deep (multimodal) layers of the owl's OT. Across layers, gamma power was tuned sharply for stimulus location and represented space topographically. In the superficial layers, induced LFP power peaked strongly in the low-gamma band (25–90 Hz) and increased gradually with visual contrast across a wide range of contrasts. Spikes recorded in these layers included presumptive axonal (input) spikes that encoded stimulus properties nearly identically with gamma oscillations and were tightly phase locked with the oscillations, suggesting that they contribute to the LFP oscillations. In the deep layers, induced LFP power was distributed across the low and high (90–140 Hz) gamma-bands and tended to reach its maximum value at relatively low visual contrasts. In these layers, gamma power was more sharply tuned for stimulus location, on average, than were somatic spike rates, and somatic spikes synchronized with gamma oscillations. Such gamma synchronized discharges of deep-layer neurons could provide a high-resolution temporal code for signaling the location of salient sensory stimuli.

scholarly journals The ionic mechanism of gamma resonance in rat striatal fast-spiking neurons

2011 ◽  
Vol 106 (6) ◽  
pp. 2936-2949 ◽  
Author(s):  
Giuseppe Sciamanna ◽  
Charles J. Wilson
Keyword(s):  
Firing Rate ◽  
Firing Pattern ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Repetitive Firing ◽  
Spike Threshold ◽  
Gamma Frequency ◽  
Subthreshold Oscillations ◽  
Fast Spiking

Striatal fast-spiking (FS) cells in slices fire in the gamma frequency range and in vivo are often phase-locked to gamma oscillations in the field potential. We studied the firing patterns of these cells in slices from rats ages 16–23 days to determine the mechanism of their gamma resonance. The resonance of striatal FS cells was manifested as a minimum frequency for repetitive firing. At rheobase, cells fired a doublet of action potentials or doublets separated by pauses, with an instantaneous firing rate averaging 44 spikes/s. The minimum rate for sustained firing was also responsible for the stuttering firing pattern. Firing rate adapted during each episode of firing, and bursts were terminated when firing was reduced to the minimum sustainable rate. Resonance and stuttering continued after blockade of Kv3 current using tetraethylammonium (0.1–1 mM). Both gamma resonance and stuttering were strongly dependent on Kv1 current. Blockade of Kv1 channels with dendrotoxin-I (100 nM) completely abolished the stuttering firing pattern, greatly lowered the minimum firing rate, abolished gamma-band subthreshold oscillations, and slowed spike frequency adaptation. The loss of resonance could be accounted for by a reduction in potassium current near spike threshold and the emergence of a fixed spike threshold. Inactivation of the Kv1 channel combined with the minimum firing rate could account for the stuttering firing pattern. The resonant properties conferred by this channel were shown to be adequate to account for their phase-locking to gamma-frequency inputs as seen in vivo.

Neuroprotective efficacy of a combination of fish oil and ferulic acid against 3-nitropropionic acid-induced oxidative stress and neurotoxicity in rats: behavioural and biochemical evidence

2014 ◽  
Vol 39 (4) ◽  
pp. 487-496 ◽  
Author(s):  
Denny Joseph K.M. ◽  
Muralidhara
Keyword(s):  
Oxidative Stress ◽  
Fish Oil ◽  
Ferulic Acid ◽  
Cytosolic Calcium ◽  
Brain Regions ◽  
Male Rats ◽  
Activity Levels ◽  
Nitropropionic Acid ◽  
3 Nitropropionic Acid

The beneficial effects of fish oil (FO) supplements on the central nervous system have been adequately demonstrated. However, FO supplementation at higher doses for longer duration is likely to cause oxidative stress in vivo. To overcome this, attempts have been made to enrich FO with known antioxidants/phytochemicals. In the present study, we examined the hypothesis that a combination of FO with ferulic acid (FA), a naturally occurring phenolic compound, is likely to provide higher degree of neuroprotection. This was examined by employing 3-nitropropionic acid (NPA), a well-known neurotoxin used to mimic behavioural and neurochemical features of Huntington’s disease. Growing male rats administered with NPA (25 mg/kg of body weight (bw) for 4 days) were provided with either FO (2 mL/kg bw), FA (50 mg/kg bw) or FO+FA for 2 weeks. Interestingly, FO+FA not only offered significant protection against NPA-induced behavioural impairments, but also markedly attenuated oxidative stress in brain regions (striatum/cerebellum) as evidenced by the reduction in reactive species, malondialdehyde, hydroperoxides and nitric oxide (NO) levels. Further, FO+FA combination restored the activities of various antioxidant enzymes and the levels of cytosolic calcium. In striatum, activity levels of acetylcholinesterase enzyme and dopamine levels were markedly restored among FO+FA rats. Interestingly, NPA-induced mitochondrial dysfunctions were also attenuated among FO+FA rats. Collectively, our findings suggest the advantage of co-treatment of FO with known antioxidants to achieve a higher therapeutic benefit in the treatment of oxidative stress-mediated neurodegenerative conditions.

scholarly journals Multichannel brain recordings in behaving Drosophila reveal oscillatory activity and local coherence in response to sensory stimulation and circuit activation

2013 ◽  
Vol 110 (7) ◽  
pp. 1703-1721 ◽  
Author(s):  
Angelique C. Paulk ◽  
Yanqiong Zhou ◽  
Peter Stratton ◽  
Li Liu ◽  
Bruno van Swinderen
Keyword(s):  
Visual Stimulation ◽  
Sensory Modality ◽  
Field Potential ◽  
Brain Regions ◽  
Oscillatory Activity ◽  
Insect Brain ◽  
Sensory Stimuli ◽  
Multichannel Recording ◽  
Frequency Bands

Neural networks in vertebrates exhibit endogenous oscillations that have been associated with functions ranging from sensory processing to locomotion. It remains unclear whether oscillations may play a similar role in the insect brain. We describe a novel “whole brain” readout for Drosophila melanogaster using a simple multichannel recording preparation to study electrical activity across the brain of flies exposed to different sensory stimuli. We recorded local field potential (LFP) activity from >2,000 registered recording sites across the fly brain in >200 wild-type and transgenic animals to uncover specific LFP frequency bands that correlate with: 1) brain region; 2) sensory modality (olfactory, visual, or mechanosensory); and 3) activity in specific neural circuits. We found endogenous and stimulus-specific oscillations throughout the fly brain. Central (higher-order) brain regions exhibited sensory modality-specific increases in power within narrow frequency bands. Conversely, in sensory brain regions such as the optic or antennal lobes, LFP coherence, rather than power, best defined sensory responses across modalities. By transiently activating specific circuits via expression of TrpA1, we found that several circuits in the fly brain modulate LFP power and coherence across brain regions and frequency domains. However, activation of a neuromodulatory octopaminergic circuit specifically increased neuronal coherence in the optic lobes during visual stimulation while decreasing coherence in central brain regions. Our multichannel recording and brain registration approach provides an effective way to track activity simultaneously across the fly brain in vivo, allowing investigation of functional roles for oscillations in processing sensory stimuli and modulating behavior.

Chemical Factors Determine Olfactory System Beta Oscillations in Waking Rats

2007 ◽  
Vol 98 (1) ◽  
pp. 394-404 ◽  
Author(s):  
Catherine A. Lowry ◽  
Leslie M. Kay
Keyword(s):  
Olfactory Bulb ◽  
Vapor Pressure ◽  
Vapor Phase ◽  
Local Field ◽  
Olfactory System ◽  
Piriform Cortex ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Beta Oscillations ◽  
Phase Concentration

Recent studies have pointed to olfactory system beta oscillations of the local field potential (15–30 Hz) and their roles both in learning and as specific responses to predator odors. To describe odorant physical properties, resultant behavioral responses and changes in the central olfactory system that may induce these oscillations without associative learning, we tested rats with 26 monomolecular odorants spanning 6 log units of theoretical vapor pressure (estimate of relative vapor phase concentration) and 10 different odor mixtures. We found odorant vapor phase concentration to be inversely correlated with investigation time on the first presentation, after which investigation times were brief and not different across odorants. Analysis of local field potentials from the olfactory bulb and anterior piriform cortex shows that beta oscillations in waking rats occur specifically in response to the class of volatile organic compounds with vapor pressures of 1–120 mmHg. Beta oscillations develop over the first three to four presentations and are weakly present for some odorants in anesthetized rats. Gamma oscillations show a smaller effect that is not restricted to the same range of odorants. Olfactory bulb theta oscillations were also examined as a measure of effective afferent input strength, and the power of these oscillations did not vary systematically with vapor pressure, suggesting that it is not olfactory bulb drive strength that determines the presence of beta oscillations. Theta band coherence analysis shows that coupling strength between the olfactory bulb and piriform cortex increases linearly with vapor phase concentration, which may facilitate beta oscillations above a threshold.

scholarly journals Perturbation of in vivo neural activity following α-Synuclein seeding in the olfactory bulb

2020 ◽  
Author(s):  
Aishwarya S. Kulkarni ◽  
Maria del Mar Cortijo ◽  
Elizabeth R. Roberts ◽  
Tamara L. Suggs ◽  
Heather B. Stover ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Neural Activity ◽  
Olfactory System ◽  
Piriform Cortex ◽  
Field Potential ◽  
Dopamine Neurons ◽  
Motor Deficits ◽  
Wild Type ◽  
Evoked Activity

AbstractBACKGROUNDParkinson’s disease (PD) neuropathology is characterized by intraneuronal protein aggregates composed of misfolded α-Synuclein (α-Syn), as well as degeneration of substantia nigra dopamine neurons. Deficits in olfactory perception and aggregation of α-Syn in the olfactory bulb (OB) are observed during early stages of PD, and have been associated with the PD prodrome, before onset of the classic motor deficits. α-Syn fibrils injected into the OB of mice cause progressive propagation of α-Syn pathology throughout the olfactory system and are coupled to olfactory perceptual deficits.OBJECTIVEWe hypothesized that accumulation of pathogenic α-Syn in the OB impairs neural activity in the olfactory system.METHODSTo address this, we monitored spontaneous and odor-evoked local field potential dynamics in awake wild type mice simultaneously in the OB and piriform cortex (PCX) one, two, and three months following injection of pathogenic preformed α-Syn fibrils in the OB.RESULTSWe detected α-Syn pathology in both the OB and PCX. We also observed that α-Syn fibril injections influenced odor-evoked activity in the OB. In particular, α-Syn fibril-injected mice displayed aberrantly high odor-evoked power in the beta spectral range. A similar change in activity was not detected in the PCX, despite high levels of α-Syn pathology.CONCLUSIONSTogether, this work provides evidence that synucleinopathy impacts in vivo neural activity in the olfactory system at the network-level.

scholarly journals Regional activity in the rat anterior cingulate cortex and insula during persistence and quitting in a physical-effort task

2020 ◽  
Author(s):  
Blake S. Porter ◽  
Kunling Li ◽  
Kristin L. Hillman
Keyword(s):  
Anterior Cingulate Cortex ◽  
Internal State ◽  
Field Potential ◽  
Cingulate Cortex ◽  
Brain Regions ◽  
Weight Lifting ◽  
Anterior Cingulate ◽  
Male Rats ◽  
Physical Effort ◽  
Internal States

AbstractAs animals carry out behaviors, particularly costly ones, they must constantly assess whether or not to persist in the behavior or quit. The anterior cingulate cortex (ACC) has been shown to assess the value of behaviors and to be especially sensitive to physical effort costs. Complimentary to these functions, the insula is thought to represent the internal state of the animal including factors such as hunger, thirst, and fatigue. Utilizing a novel weight lifting task for rats, we characterized the local field potential (LFP) activity of the ACC and anterior insula (AI) during effort expenditure. In the task male rats are challenged to work for sucrose reward, which costs progressively more effort over time to obtain. Rats are able to quit the task at any point. We found modest shifts in LFP theta (7-9 Hz) activity as the task got progressively more difficult in terms of absolute effort expenditure. However, when the LFP data were analyzed based on the rat’s relative progress towards quitting the task, or performance state, substantial shifts in LFP power in the theta and gamma (55-100 Hz) frequency bands were observed in ACC and AI. Both ACC and AI theta power decreased as the rats got closer to quitting, while ACC and AI gamma power increased. Furthermore, coherency between ACC and AI in the delta (2-4 Hz) range shifted alongside the rat’s performance state. Overall we show that ACC and AI LFP activity changes correlate to the rats’ relative performance state in an effort-based task.Significance StatementAnimals need to assess whether or not a behavior is worth pursuing based on their internal states (e.g., hunger, fatigue) and the costs and benefits of the behavior. However, internal states often change as behaviors are carried out, such as becoming fatigued, necessitating constant reassessment as to whether to continue the behavior or quit. We characterized brain activity in the anterior cingulate cortex and insula, brain regions involved in cost-benefit decision making and internal state representations, respectively, as rats carried out a challenging physical-effort task. Both brain regions showed significant shifts in activity as the rats approached their quitting point. Our study provides one of the first characterizations of neural activity as an animal decides to quit an effortful task.

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