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.

scholarly journals Primary sensorimotor cortex exhibits complex dependencies of spike-field coherence on neuronal firing rates, field power, and behavior

2018 ◽  
Vol 120 (1) ◽  
pp. 226-238 ◽  
Author(s):  
F. I. Arce-McShane ◽  
B. J. Sessle ◽  
C. F. Ross ◽  
N. G. Hatsopoulos
Keyword(s):  
Functional Connectivity ◽  
Firing Rate ◽  
Local Field ◽  
Sensorimotor Cortex ◽  
Field Potential ◽  
Neuronal Firing ◽  
Firing Rates ◽  
Linear Relationships ◽  
And Behavior ◽  
Field Coherence

Spike-field coherence (SFC) is widely used to assess cortico-cortical interactions during sensorimotor behavioral tasks by measuring the consistency of the relative phases between the spike train of a neuron and the concurrent local field potentials (LFPs). Interpretations of SFC as a measure of functional connectivity are complicated by theoretical work suggesting that estimates of SFC depend on overall neuronal activity. We evaluated the dependence of SFC on neuronal firing rates, LFP power, and behavior in the primary motor (MIo) and primary somatosensory (SIo) areas of the orofacial sensorimotor cortex of monkeys ( Macaca mulatta) during performance of a tongue-protrusion task. Although we occasionally observed monotonically increasing linear relationships between coherence and firing rate, we most often found highly complex, nonmonotonic relationships in both SIo and MIo and sometimes even found that coherence decreased with increasing firing rate. The lack of linear relationships was also true for both LFP power and tongue-protrusive force. Moreover, the ratio between maximal firing rate and the firing rate at peak coherence deviated significantly from unity, indicating that MIo and SIo neurons achieved maximal SFC at a submaximal level of spiking. Overall, these results point to complex relationships of SFC to firing rates, LFP power, and behavior during sensorimotor cortico-cortical interactions: coherence is a measure of functional connectivity whose magnitude is not a mere monotonic reflection of changes in firing rate, LFP power, or the relevantly controlled behavioral parameter. NEW & NOTEWORTHY The concern that estimates of spike-field coherence depend on the firing rates of single neurons has influenced analytical methods employed by experimental studies investigating the functional interactions between cortical areas. Our study shows that the overwhelming majority of the estimated spike-field coherence exhibited complex relations with firing rates of neurons in the orofacial sensorimotor cortex. The lack of monotonic relations was also evident after testing the influence of local field potential power and force on spike-field coherence.

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 Fodor on multiple realizability and nonreductive physicalism: Why the argument does not work

2020 ◽  
Vol 35 (1) ◽  
pp. 59
Author(s):  
José Luis Bermúdez ◽  
Arnon Cahen
Keyword(s):  
Local Field ◽  
Local Field Potential ◽  
Field Potential ◽  
Multiple Realizability ◽  
Neural Firing ◽  
Nonreductive Physicalism ◽  
Firing Patterns ◽  
Firing Rates ◽  
Neural Populations ◽  
Mental Events

This paper assesses Fodor’s well-known argument from multiple realizability to nonreductive physicalism. Recent work has brought out that the empirical case for cross-species multiple realizability is weak at best and so we consider whether the argument can be rebooted using a “thin” notion of intra-species multiple realizability, taking individual neural firing patterns to be the realizers of mental events. We agree that there are no prospects for reducing mental events to individual neural firing patterns. But there are more plausible candidates for the neural realizers of mental events out there, namely, global neural properties such as the average firing rates of neural populations, or the local field potential. The problem for Fodor’s argument is that those global neural properties point towards reductive versions of physicalism.

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.

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