scholarly journals Microelectrode recording findings within the tractography-defined ventral intermediate nucleus

2017 ◽  
Vol 126 (5) ◽  
pp. 1669-1675 ◽  
Author(s):  
Nicolas Kon Kam King ◽  
Vibhor Krishna ◽  
Diellor Basha ◽  
Gavin Elias ◽  
Francesco Sammartino ◽  
...  
Keyword(s):  
Firing Rate ◽  
Local Field ◽  
Local Field Potential ◽  
Structural Connectivity ◽  
Field Potential ◽  
Area Under The Curve ◽  
Microelectrode Recording ◽  
Intermediate Nucleus ◽  
Beta Power ◽  
Ventral Intermediate Nucleus

OBJECTIVEThe ventral intermediate nucleus (VIM) of the thalamus is not visible on structural MRI. Therefore, direct VIM targeting methods for stereotactic tremor surgery are desirable. The authors previously described a direct targeting method for visualizing the VIM and its structural connectivity using deterministic tractography. In this combined electrophysiology and imaging study, the authors investigated the electrophysiology within this tractography-defined VIM (T-VIM).METHODSThalamic neurons were classified based on their relative location to the T-VIM: dorsal, within, and ventral to the T-VIM. The authors identified the movement-responsive cells (kinesthetic and tremor cells), performed spike analysis (firing rate and burst index), and local field potential analysis (area under the curve for 13–30 Hz). Tremor efficacy in response to microstimulation along the electrode trajectory was also assessed in relation to the T-VIM.RESULTSSeventy-three cells from a total of 9 microelectrode tracks were included for this analysis. Movement-responsive cells (20 kinesthetic cells and 26 tremor cells) were identified throughout the electrode trajectories. The mean firing rate and burst index of cells (n = 27) within the T-VIM are 18.8 ± 9.8 Hz and 4.5 ± 5.4, respectively. Significant local field potential beta power was identified within the T-VIM (area under the curve for 13–30 Hz = 6.6 ± 7.7) with a trend toward higher beta power in the dorsal T-VIM. The most significant reduction in tremor was also observed in the dorsal T-VIM.CONCLUSIONSThe electrophysiological findings within the VIM thalamus defined by tractography, or T-VIM, correspond with the known microelectrode recording characteristics of the VIM in patients with tremor.

scholarly journals Pharmacological manipulation of the olfactory bulb modulates beta oscillations: testing model predictions

2018 ◽  
Vol 120 (3) ◽  
pp. 1090-1106 ◽  
Author(s):  
Bolesław L. Osinski ◽  
Alex Kim ◽  
Wenxi Xiao ◽  
Nisarg M. Mehta ◽  
Leslie M. Kay
Keyword(s):  
Nmda Receptor ◽  
Olfactory Bulb ◽  
Local Field ◽  
Local Field Potential ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Receptor Activation ◽  
Beta Oscillations ◽  
Pyriform Cortex ◽  
Beta Power

The mammalian olfactory bulb (OB) generates gamma (40–100 Hz) and beta (15–30 Hz) local field potential (LFP) oscillations. Gamma oscillations arise at the peak of inhalation supported by dendrodendritic interactions between glutamatergic mitral cells (MCs) and GABAergic granule cells (GCs). Beta oscillations are induced by odorants in learning or odor sensitization paradigms, but their mechanism and function are still poorly understood. When centrifugal OB inputs are blocked, beta oscillations disappear, but gamma oscillations persist. Centrifugal inputs target primarily GABAergic interneurons in the GC layer (GCL) and regulate GC excitability, suggesting a causal link between beta oscillations and GC excitability. Our previous modeling work predicted that convergence of excitatory/inhibitory inputs onto MCs and centrifugal inputs onto GCs increase GC excitability sufficiently to produce beta oscillations primarily through voltage dependent calcium channel-mediated GABA release, independently of NMDA channels. We test some of the predictions of this model by examining the influence of NMDA and muscarinic acetylcholine (ACh) receptors, which affect GC excitability in different ways, on beta oscillations. A few minutes after intrabulbar infusion, scopolamine (muscarinic antagonist) suppressed odor-evoked beta in response to a strong stimulus but increased beta power in response to a weak stimulus, as predicted by our model. Pyriform cortex (PC) beta power was unchanged. Oxotremorine (muscarinic agonist) suppressed all oscillations, likely from overinhibition. APV, an NMDA receptor antagonist, suppressed gamma oscillations selectively (in OB and PC), lending support to the model’s prediction that beta oscillations can be supported independently of NMDA receptors. NEW & NOTEWORTHY Olfactory bulb local field potential beta oscillations appear to be gated by GABAergic granule cell excitability. Reducing excitability with scopolamine reduces beta induced by strong odors but increases beta induced by weak odors. Beta oscillations rely on the same synapse as gamma oscillations but, unlike gamma, can persist in the absence of NMDA receptor activation. Pyriform cortex beta oscillations maintain power when olfactory bulb beta power is low, and the system maintains beta band coherence.

Synchronization of neurons during local field potential oscillations in sensorimotor cortex of awake monkeys

1996 ◽  
Vol 76 (6) ◽  
pp. 3968-3982 ◽  
Author(s):  
V. N. Murthy ◽  
E. E. Fetz
Keyword(s):  
Firing Rate ◽  
Local Field ◽  
Sensorimotor Cortex ◽  
Local Field Potential ◽  
Field Potential ◽  
Peak Latency ◽  
Peak Amplitude ◽  
Firing Rates ◽  
Multiple Units ◽  
40 Hz

1. The neural activity associated with 20- to 40-Hz oscillations in sensorimotor cortex of awake monkeys was investigated by recording action potentials of single and multiple units. At a given site, activity of many units became synchronized with local field potential (LFP) oscillations. Cycle-triggered histograms (CTHs) of unit spikes aligned on cycles of LFP oscillations indicated that about two thirds of the recorded units (n = 268) were entrained with LFP oscillations. On average, units had the highest probability of spiking 2.7 ms before peak LFP negativity, corresponding to a -27.6 degrees phase shift relative to the negative peak of the LFP. 2. The average relative modulation amplitude (RMA), defined as the ratio of amplitude of oscillatory component of CTH and the baseline multiplied by 100, was 45 +/- 27% (mean +/- SD). The RMAs of single units did not differ significantly from those of multiple units. 3. Phase shifts and RMAs did not vary systematically with the cortical depth of recorded units. 4. Autocorrelation histograms (ACHs) of entrained units exhibited clear 20- to 40-Hz periodicity if they were compiled with spikes that occurred during oscillatory episodes in LFPs. ACHs of spikes outside oscillatory episodes usually did not show periodicity. Global ACHs of all spikes typically showed weak or no evidence of periodic activity. 5. Cross-correlation histograms (CCHs) between pairs of units complied with all spikes, whether they occurred during or outside LFP oscillations, seldom revealed significant features (19 of 134 pairs or 14%). However, CCHs compiled with spikes that occurred during oscillatory episodes (OS-CCHs) had significant features in 67 of 134 pairs recorded ipsilaterally; in these 67 cases, units at both sites showed modulation in CTHs. 6. The latencies of the OS-CCH peaks (taking the medial unit as reference) were normally distributed about a mean of -0.5 +/- 13 ms. Normalized peak height of CCHs (peak/baseline x 100) was, on average, 14.3 +/- 11.2%. Peak latency and normalized peak amplitude did not change significantly with horizontal separation of recorded precentral pairs up to 14 mm. 7. Units in the left and right hemispheres could become synchronized during oscillations. Significant features in OS-CCH were detected in 22 of 42 pairs of units recorded bilaterally. The average peak latency was 0.2 +/- 8.0 ms and the average normalized peak amplitude was 10 +/- 8%. These parameters did not differ significantly from those for ipsilateral OS-CCHs. 8. Oscillations tended to affect both the temporal structure and net rate of unit firing. For each unit, the firing rate was clamped to a narrow range of frequencies during oscillatory episodes. The coefficient of variation (SD/mean) of firing rates was significantly reduced during oscillatory episodes compared with prior rates (P < 0.001, paired t-test). However, the overall mean firing rate of each unit during all oscillatory episodes did not differ from its average rate immediately before the episodes. Thus oscillatory episodes tended to clamp mean firing rates to the cells' average rates outside episodes. 9. The strength of synchronization between units during oscillatory episodes was unrelated to their involvement in the task. For pairs of precentral units recorded ipsilaterally, the probability of occurrence of significant features in the OS-CCH was slightly larger when both units of the pair were task related (33 of 56 pairs or 59%) than when only one unit was task related (20 of 39 pairs or 51%) or neither unit was task related (7 of 16 or 44%). However, these differences were not statistically significant. The magnitude of the correlation peak and the latency to peak were also not significantly different for the three cases. 10. These results suggest that units across wide regions can become transiently synchronized specifically during LFP oscillations, even if their spikes are uncorrelated during nonoscillatory periods.

Vagus Nerve Stimulation Induced Synchrony Modulation of Local Field Potential in the Rat Cerebral Cortex

2013 ◽  
Vol 133 (8) ◽  
pp. 1493-1500 ◽  
Author(s):  
Ryuji Kano ◽  
Kenichi Usami ◽  
Takahiro Noda ◽  
Tomoyo I. Shiramatsu ◽  
Ryohei Kanzaki ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Vagus Nerve ◽  
Local Field ◽  
Nerve Stimulation ◽  
Local Field Potential ◽  
Vagus Nerve Stimulation ◽  
Field Potential ◽  
Rat Cerebral Cortex

Exploiting the directional local field potential recording capability of a new DBS lead for functional targeting in Parkinson’s disease

2015 ◽  
Vol 8 (2) ◽  
pp. 380
Author(s):  
M.A.J. Lourens ◽  
M.F. Contarino ◽  
R. Verhagen ◽  
P. van den Munckhof ◽  
P.R. Schuurman ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Local Field ◽  
Local Field Potential ◽  
Field Potential ◽  
Potential Recording ◽  
Field Potential Recording

Cultured olfactory interneurons from Limax maximus: optical and electrophysiological studies of transmitter-evoked responses

1993 ◽  
Vol 69 (6) ◽  
pp. 1940-1947 ◽  
Author(s):  
L. D. Rhines ◽  
P. G. Sokolove ◽  
J. Flores ◽  
D. W. Tank ◽  
A. Gelperin
Keyword(s):  
Action Potential ◽  
Intracellular Calcium ◽  
Local Field ◽  
Local Field Potential ◽  
Field Potential ◽  
Optical Measurements ◽  
Optical Studies ◽  
Isolated Cells ◽  
Fura 2 ◽  
Limax Maximus

1. The olfactory processing network in the procerebral (PC) lobe of the terrestrial mollusk Limax maximus exhibits a coherent oscillation of local field potential that is modulated by odor input. To understand the cellular basis of this oscillation, we developed a cell culture preparation of isolated PC neurons and studied the responses of isolated cells to stimulation with neurotransmitters known to be present in the PC lobe. 2. The distribution of PC soma diameters suggests at least two different populations of neurons. Approximately 95% of isolated cells had soma diameters of 7-8 microns, with the remaining cells having larger diameters (10-15 microns). 3. Extracellular measurements of action potentials and optical measurements of intracellular calcium concentrations in fura-2-loaded cells were made. Serotonin and dopamine excited PC neurons and promoted transitions from steady to bursty activity. Both amines elicited increases in intracellular calcium, presumably concomitant with the increase in action-potential frequency. 4. Glutamate suppressed action-potential firing and reduced intracellular calcium. This effect was seen most clearly when glutamate was applied to cells excited by high potassium medium. Quisqualate is an effective glutamate agonist in this system, whereas kainate is not. 5. Combined with anatomic and biochemical data and with studies of the effects of these neurotransmitters on the oscillating local field potential of the intact PC network, the data from isolated PC neurons are consistent with the hypothesis that dopamine and serotonin modulate network dynamics, whereas glutamate is involved in generating the basic oscillation of local field potential in the PC. 6. The optical studies of fura-2-loaded cells showed that several treatments that increase the rate of action-potential production lead to elevations in intracellular calcium. Optical studies of intracellular calcium may be useful for multisite measurements of activity in the intact, oscillating PC lobe network.

scholarly journals Increased neural correlations in primate auditory cortex during slow-wave sleep

2013 ◽  
Vol 109 (11) ◽  
pp. 2732-2738 ◽  
Author(s):  
Elias B. Issa ◽  
Xiaoqin Wang
Keyword(s):  
Auditory Cortex ◽  
Spontaneous Activity ◽  
Slow Wave ◽  
Local Field ◽  
Local Field Potential ◽  
Slow Wave Sleep ◽  
Field Potential ◽  
Sensory Stimulation ◽  
Acoustic Stimulation ◽  
Functional Connections

During sleep, changes in brain rhythms and neuromodulator levels in cortex modify the properties of individual neurons and the network as a whole. In principle, network-level interactions during sleep can be studied by observing covariation in spontaneous activity between neurons. Spontaneous activity, however, reflects only a portion of the effective functional connectivity that is activated by external and internal inputs (e.g., sensory stimulation, motor behavior, and mental activity), and it has been shown that neural responses are less correlated during external sensory stimulation than during spontaneous activity. Here, we took advantage of the unique property that the auditory cortex continues to respond to sounds during sleep and used external acoustic stimuli to activate cortical networks for studying neural interactions during sleep. We found that during slow-wave sleep (SWS), local (neuron-neuron) correlations are not reduced by acoustic stimulation remaining higher than in wakefulness and rapid eye movement sleep and remaining similar to spontaneous activity correlations. This high level of correlations during SWS complements previous work finding elevated global (local field potential-local field potential) correlations during sleep. Contrary to the prediction that slow oscillations in SWS would increase neural correlations during spontaneous activity, we found little change in neural correlations outside of periods of acoustic stimulation. Rather, these findings suggest that functional connections recruited in sound processing are modified during SWS and that slow rhythms, which in general are suppressed by sensory stimulation, are not the sole mechanism leading to elevated network correlations during sleep.

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