Stimulus techniques and microelectrode recordings of subthalamic-nuclei neurons in Parkinson`s during functional-neurosurgery

This study discusses the various procedures and issues involved in the acquisition of microelectrode recordings (MER) signals of subthalamic nucleus stimulations with induced deep brain stimulation electrodes very rigorously. Bellicose-invasive physiological detections through the methods of sub cortical physio logical detections, electrical induced stimulations and micro electrode recordings, stereo-tactic technique, macro-stimulation, stereo-tactic functional neurosurgical technique, stimulations such as macro and micro, induced stimuli with current and microelectrode recordings, impedance information monitoring, micro injections of test substances, evoked potentials, biomarkers/local field potentials, microelectrode fabrication methods and setups, sub cortical atlas-mapping with micro recording/microelectrode recording (M.E.R.). Thus, the study is very significant to the electrophysiological neurosurgical point of view and is very useful to the field of microelectrode recording and functional neurosurgery. This study is concerned with invasive physiological detection of deep brain structures with micro- or macro-electrodes prior to surgery followed by imaging techniques and their use in cortical and subcortical detection; detection relevant to the superficial cerebral cortex regions.

Edge detections of MER Signals of STN with DBS micro electrode local field potential acquisitions in Parkinson`s

Deep brain stimulation of the subthalamic nucleus (STN) is a highly effective treatment for motor symptoms of Parkinson’s disease. Sub thalamic nucleus deep brain stimulation (STN-DBS) is a therapeutic surgical procedure for reducing the symptoms Parkinson’s and restoring and increasing the motor functioning. However, precise intraoperative edge or perimeter detection of STN remains a procedural challenge. In this study, we present the micro electrode signals recordings (MER) of STNs and local field potentials (LFPs) were acquired from deep brain stimulation macro electrodes during trajectory towards STN, in Parkinson patients. The frequency versus intensity atlas of field potential activity was obtained and further than investigated in distinct sub band’s, to explore whether field potentials activity can be employed for STN edge detection. STN perimeter detections by means of L F Ps were evaluated to edge predictions by way of the functional stereotactic DBS neurosurgeon, based on micro electrode derived, single unit recordings (M E R – S N A of S T Ns). The findings show variation amongst M E R – S N A and macro electrode L F P-signals gathering through MER-system pertaining to the d o r s a l S T N b o r d e r of -1.00±0.85mm plus -0.42±1.08 mm in the and frequencies, correspondingly. For these sub band`s, root mean square of the voids was found to be 1.27milli meters and 1.07milli meters. The Assessment of other sub band`s didn`t set a limit for differentiating the posterior (c a u d a l) point of sub-thalamic nuclei. We may infer that In conclusion, macro electrode signal acquisitions of STNs derived L F P gatherings might offer an unconventional methodology in the direction of m e r – s n a, for detecting the aimed target subthalamic nucleus borders during DBS-surgery.

Prefrontal cortical plasticity during learning of cognitive tasks

Training in working memory tasks is associated with lasting changes in prefrontal cortical activity. To assess the neural activity changes induced by training, we recorded single units, multi-unit activity (MUA) and local field potentials (LFP) with chronic electrode arrays implanted in the prefrontal cortex of two monkeys, throughout the period they were trained to perform cognitive tasks. Mastering different task phases was associated with distinct changes in neural activity, which included recruitment of larger numbers of neurons, increases or decreases of their firing rate, changes in the correlation structure between neurons, and redistribution of power across LFP frequency bands. In every training phase, changes induced by the actively learned task were also observed in a control task, which remained the same across the training period. Our results reveal how learning to perform cognitive tasks induces plasticity of prefrontal cortical activity, and how activity changes may generalize between tasks.

Grasp-Squeeze Adaptation to Changes in Object Compliance Leads to Dynamic Beta-Band Communication Between Primary Somatosensory and Motor Cortices

In asking the question of how the brain adapts to changes in the softness of manipulated objects, we studied dynamic communication between the primary sensory and motor cortical areas when nonhuman primates grasp and squeeze an elastically deformable manipulandum to attain an instructed force level. We focused on local field potentials recorded from S1 and M1 via intracortical microelectrode arrays. We computed nonparametric spectral Granger Causality to assess directed cortico-cortical interactions between these two areas. We demonstrate that the time-causal relationship between M1 and S1 is bidirectional in the beta-band (15-30Hz) and that this interareal communication develops dynamically as the subjects adjust the force of hand squeeze to reach the target level. In particular, the directed interaction is strongest when subjects are focused on maintaining the instructed force of hand squeeze in a steady state for several seconds. When the manipulandum’s compliance is abruptly changed, beta-band interareal communication is interrupted for a short period (~ 1 second) and then is re-established once the subject has reached a new steady state. These results suggest that transient beta oscillations can provide a communication subspace for dynamic cortico-cortical S1-M1 interactions during maintenance of steady sensorimotor states.

The Effect of Neural Entropy during Deep Brain Stimulation of Cortex-Basal Ganglia Network Model.

Researchers reported decreased nerve entropy Patients with Parkinson's disease (PD) have abnormalities in their basal ganglia (BG). Studies of local field potentials (LFPs) recorded from the hypothalamus and single unit recordings of GP neurons showed this reduction to be significant. According to this hypothesis, these changes are consistent with changes in the ability of the basal ganglion network to encode PD information. Our deep brain stimulation of cortical basal ganglia (DBS) model includes single LFP recordings and shows how entropy changes during DBS. In addition to the extracellular stimulation of supplied STN fibers and LFP mimetics, which are detected differently on a registered electrode, this model includes osteoclast activation and anti-apoptosis. In the DBS network, the firing pattern fluctuated between high-frequency and low-frequency stimuli, since gp neurons in the network showed a decrease in entropy when a high-frequency stimulus was applied and an increase in entropy when a low-frequency stimulus was applied. Second hand. Changes in neural entropy after DBS have been reported experimentally. The simulation results were consistent

Changes in the spatiotemporal pattern of spontaneous activity across a cortical column after noise trauma

In the auditory modality, noise trauma has often been used to investigate cortical plasticity as it causes cochlear hearing loss. One limitation of these past studies, however, is that the effects of noise trauma have been mostly documented at the granular layer, which is the main cortical recipient of thalamic inputs. Importantly, the cortex is composed of six different layers each having its own pattern of connectivity and specific role in sensory processing. The present study aims at investigating the effects of acute and chronic noise trauma on the laminar pattern of spontaneous activity in primary auditory cortex of the anesthetized guinea pig. We show that spontaneous activity is dramatically altered across cortical layers after acute and chronic noise-induced hearing loss. First, spontaneous activity was globally enhanced across cortical layers, both in terms of firing rate and amplitude of spike-triggered average of local field potentials. Second, current source density on (spontaneous) spike-triggered average of local field potentials indicates that current sinks develop in the supra- and infragranular layers. These latter results suggest that supragranular layers become a major input recipient and that the propagation of spontaneous activity over a cortical column is greatly enhanced after acute and chronic noise-induced hearing loss. We discuss the possible mechanisms and functional implications of these changes.

Decreased Phase–Amplitude Coupling Between the mPFC and BLA During Exploratory Behaviour in Chronic Unpredictable Mild Stress-Induced Depression Model of Rats

Depression is a common neuropsychiatric illness observed worldwide, and reduced interest in exploration is one of its symptoms. The control of dysregulated medial prefrontal cortex (mPFC) over the basolateral amygdala (BLA) is related to depression. However, the oscillation interaction in the mPFC-BLA circuit has remained elusive. Therefore, this study used phase–amplitude coupling (PAC), which provides complicated forms of information transmission by the phase of low-frequency rhythm, modulating the amplitude of high-frequency rhythm, and has a potential application for the treatment of neurological disease. The chronic unpredictable mild stress (CUMS) was used to prepare the rat models of depression. Moreover, multichannel in vivo recording was applied to obtain the local field potentials (LFPs) of the mPFC, the BLA in rats in control, and CUMS groups, while they explored the open field. The results showed prominent coupling between the phase of theta oscillation (4–12 Hz) in the mPFC and the amplitude of high-gamma oscillation (70–120 Hz) in the BLA. Compared to the control group, this theta–gamma PAC was significantly decreased in the CUMS group, which was accompanied by the diminished exploratory behaviour. The results indicate that the coupling between the phase of theta in the mPFC and the amplitude of gamma in the BLA is involved in exploratory behaviour, and this decreased coupling may inhibit exploratory behaviour of rats exposed to CUMS.

The Spatial Reach of Neuronal Coherence and Spike-field Coupling across the Human Neocortex

Neuronal coherence is thought to be a fundamental mechanism of communication in the brain, where synchronized field potentials coordinate synaptic and spiking events to support plasticity and learning. Although the spread of field potentials has garnered great interest, little is known about the spatial reach of phase synchronization, or neuronal coherence. Functional connectivity between different brain regions is known to occur across long distances, but the locality of coherence within a brain region is understudied. Here we used simultaneous recordings from electrocorticography (ECoG) grids and high-density microelectrode arrays to estimate the spatial reach of neuronal coherence and spike-field coherence (SFC) across frontal, temporal, and occipital cortices during cognitive tasks in humans. We observed the strongest coherence within a 2-3 cm distance from the microelectrode arrays, potentially defining an effective range for local communication. This range was relatively consistent across brain regions, spectral frequencies, and cognitive tasks. The magnitude of coherence showed power law decay with increasing distance from the microelectrode arrays, where the highest coherence occurred between ECoG contacts, followed by coherence between ECoG and deep cortical LFP, and then SFC (i.e., ECoG > LFP > SFC). The spectral frequency of coherence also affected its magnitude. Alpha coherence (8-14 Hz) was generally higher than other frequencies for signals nearest the microelectrode arrays, whereas delta coherence (1-3 Hz) was higher for signals that were farther away. Action potentials in all brain regions were most coherent with the phase of alpha oscillations, which suggests that alpha waves could play a larger, more spatially local role in spike timing than other frequencies. These findings provide a deeper understanding of the spatial and spectral dynamics of neuronal coherence, further advancing knowledge about how activity propagates across the human brain.