8 research outputs found
Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation
Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimated electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.8 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r = 0.86) and depth (r = 0.88) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials
Brain and Human Body Modeling 2020
​This open access book describes modern applications of computational human modeling in an effort to advance neurology, cancer treatment, and radio-frequency studies including regulatory, safety, and wireless communication fields. Readers working on any application that may expose human subjects to electromagnetic radiation will benefit from this book’s coverage of the latest models and techniques available to assess a given technology’s safety and efficacy in a timely and efficient manner. Describes computational human body phantom construction and application; Explains new practices in computational human body modeling for electromagnetic safety and exposure evaluations; Includes a survey of modern applications for which computational human phantoms are critical
Using Brain Stimulation to Enhance Working Memory: A Charged Topic
Although working memory (WM) training programs consistently result in improvement on the trained task, benefit is typically short-lived and extends only to tasks very similar to the trained task. Pairing repeated performance of a WM task with brain stimulation may encourage plasticity in brain networks involved in WM task performance, thereby improving the training benefit. In the current study, transcranial direct current stimulation (tDCS) was paired with performance of a WM task. In Experiment 1, participants performed a spatial location-monitoring n-back during stimulation, while Experiment 2 used a verbal identity-monitoring n-back. In each experiment, participants received either active (2.0 mA) or sham (0.1 mA) stimulation with the anode placed over either the right or the left dorsolateral prefrontal cortex (DLPFC) and the cathode placed extracephalically. In Experiment 1, only participants receiving active stimulation with the anode placed over the right DLPFC showed marginal improvement on the trained spatial n-back, which did not extend to a near transfer (verbal n-back) or far transfer (fluid intelligence) task. In Experiment 2, both left and right anode placements led to improvement, and right DLPFC stimulation resulted in numerical (though not sham-adjusted) improvement on the near transfer (spatial n-back) and far transfer (fluid intelligence) task
PRELIMINARY FINDINGS OF A POTENZIATED PIEZOSURGERGICAL DEVICE AT THE RABBIT SKULL
The number of available ultrasonic osteotomes has remarkably increased. In vitro and in vivo studies
have revealed differences between conventional osteotomes, such as rotating or sawing devices, and
ultrasound-supported osteotomes (Piezosurgery®) regarding the micromorphology and roughness
values of osteotomized bone surfaces.
Objective: the present study compares the micro-morphologies and roughness values of
osteotomized bone surfaces after the application of rotating and sawing devices, Piezosurgery
Medical® and Piezosurgery Medical New Generation Powerful Handpiece.
Methods: Fresh, standard-sized bony samples were taken from a rabbit skull using the following
osteotomes: rotating and sawing devices, Piezosurgery Medical® and a Piezosurgery Medical New
Generation Powerful Handpiece. The required duration of time for each osteotomy was recorded.
Micromorphologies and roughness values to characterize the bone surfaces following the different
osteotomy methods were described. The prepared surfaces were examined via light microscopy,
environmental surface electron microscopy (ESEM), transmission electron microscopy (TEM), confocal
laser scanning microscopy (CLSM) and atomic force microscopy. The selective cutting of mineralized
tissues while preserving adjacent soft tissue (dura mater and nervous tissue) was studied. Bone
necrosis of the osteotomy sites and the vitality of the osteocytes near the sectional plane were
investigated, as well as the proportion of apoptosis or cell degeneration.
Results and Conclusions: The potential positive effects on bone healing and reossification
associated with different devices were evaluated and the comparative analysis among the different
devices used was performed, in order to determine the best osteotomes to be employed during
cranio-facial surgery
Serotonergic modulation of the ventral pallidum by 5HT1A, 5HT5A, 5HT7 AND 5HT2C receptors
Introduction: Serotonin's involvement in reward processing is controversial. The large number of serotonin receptor
sub-types and their individual and unique contributions have been difficult to dissect out, yet understanding how
specific serotonin receptor sub-types contribute to its effects on areas associated with reward processing is an
essential step.
Methods: The current study used multi-electrode arrays and acute slice preparations to examine the effects of
serotonin on ventral pallidum (VP) neurons.
Approach for statistical analysis: extracellular recordings were spike sorted using template matching and principal
components analysis, Consecutive inter-spike intervals were then compared over periods of 1200 seconds for each
treatment condition using a student’s t test.
Results and conclusions: Our data suggests that excitatory responses to serotonin application are pre-synaptic in
origin as blocking synaptic transmission with low-calcium aCSF abolished these responses. Our data also suggests
that 5HT1a, 5HT5a and 5HT7 receptors contribute to this effect, potentially forming an oligomeric complex, as 5HT1a
antagonists completely abolished excitatory responses to serotonin application, while 5HT5a and 5HT7 only reduced
the magnitude of excitatory responses to serotonin. 5HT2c receptors were the only serotonin receptor sub-type
tested that elicited inhibitory responses to serotonin application in the VP. These findings, combined with our
previous data outlining the mechanisms underpinning dopamine's effects in the VP, provide key information, which
will allow future research to fully examine the interplay between serotonin and dopamine in the VP. Investigation of
dopamine and serotonins interaction may provide vital insights into our understanding of the VP's involvement in
reward processing. It may also contribute to our understanding of how drugs of abuse, such as cocaine, may hijack
these mechanisms in the VP resulting in sensitization to drugs of abuse
Head and Neck Critical Illness
There are various malignant tumors in the head and neck area, including oral cavity, pharynx, sinonasal cavity, and salivary glands. Squamous cell carcinoma is the most common cancer among head and neck cancers. In salivary glands, there are many types of malignancies that can develop, such as malignant lymphoma, adenoid cystic carcinoma, adenocarcinoma, and mesenchymal tumors. In a clinical setting, imaging, such as computed tomography (CT) and magnetic resonance imaging (MRI), is very important in terms of the prediction of the histological type and the evaluation of the extent of invasion of adjacent structures. In basic research, there are few animal models in head and neck malignancies. In this Special Issue, we broadly discuss the basic and clinical research in head and neck malignancies