scholarly journals Medial Lateral Extent of Thermal and Pain Sensations Evoked By Microstimulation in Somatic Sensory Nuclei of Human Thalamus

2003 ◽  
Vol 90 (4) ◽  
pp. 2367-2377 ◽  
Author(s):  
Shinji Ohara ◽  
Fred A. Lenz
Keyword(s):  
Posterior Part ◽  
Posterior Region ◽  
The Core ◽  
Medial Nucleus ◽  
Human Thalamus ◽  
Lateral Plane ◽  
Sensory Nucleus ◽  
Lateral Extent

We explored the region of human thalamic somatic sensory nucleus (ventral caudal, Vc) with threshold microstimulation during stereotactic procedures for the treatment of tremor (124 thalami, 116 patients). Warm sensations were evoked more frequently in the posterior region than in the core. Proportion of sites where microstimulation evoked cool and pain sensations was not different between the core and the posterior region. In the core, sites where both thermal and pain sensations were evoked were distributed similarly in the medial two planes and the lateral plane. In the posterior region, however, warm sensations were evoked more frequently in the lateral plane (10.8%) than in the medial planes (3.9%). No mediolateral difference was found for sites where pain and cool sensations were evoked. The presence of sites where stimulation evoked taste or where receptive and projected fields were located on the pharynx were used as landmarks of a plane located as medial as the posterior part of the ventral medial nucleus (VMpo). Microstimulation in this plane evoked cool, warm, and pain sensations. The results suggest that thermal and pain sensations are processed in the region of Vc as far medial as VMpo. Thermal and pain sensations seem to be mediated by neural elements in a region likely including the core of Vc, VMpo, and other nuclei posterior and inferior to Vc.

Petrophysical Rocks: Electrofacies and Lithofacies

2014 ◽  
Author(s):  
John H. Doveton
Keyword(s):  
Particle Size ◽  
Physical Properties ◽  
Sedimentary Rocks ◽  
Well Control ◽  
The Core ◽  
Lateral Extent ◽  
Petrophysical Logs ◽  
Definition Of

Many years ago, the classification of sedimentary rocks was largely descriptive and relied primarily on petrographic methods for composition and granulometry for particle size. The compositional aspect broadly matches the goals of the previous chapter in estimating mineral content from petrophysical logs. With the development of sedimentology, sedimentary rocks were now considered in terms of the depositional environment in which they originated. Uniformitarianism, the doctrine that the present is the key to the past, linked the formation of sediments in the modern day to their ancient lithified equivalents. Classification was now structured in terms of genesis and formalized in the concept of “facies.” A widely quoted definition of facies was given by Reading (1978) who stated, “A facies should ideally be a distinctive rock that forms under certain conditions of sedimentation reflecting a particular process or environment.” This concept identifies facies as process products which, when lithified in the subsurface, form genetic units that can be correlated with well control to establish the geological architecture of a field. The matching of facies with modern depositional analogs means that dimensional measures, such as shape and lateral extent, can be used to condition reasonable geomodels, particularly when well control is sparse or nonuniform. Most wells are logged rather than cored, so that the identification of facies in cores usually provides only a modicum of information to characterize the architecture of an entire field. Consequently, many studies have been made to predict lithofacies from log measurements in order to augment core observations in the development of a satisfactory geomodel that describes the structure of genetic layers across a field. The term “electrofacies” was introduced by Serra and Abbott (1980) as a way to characterize collective associations of log responses that are linked with geological attributes. They defined electrofacies to be “the set of log responses which characterizes a bed and permits it to be distinguished from the others.” Electrofacies are clearly determined by geology, because physical properties of rocks. The intent of electrofacies identification is generally to match them with lithofacies identified in the core or an outcrop.

scholarly journals Complex of global functional network as the core of consciousness

2021 ◽  
Author(s):  
Keiichi Onoda
Keyword(s):  
Dynamic System ◽  
Brain Activity ◽  
Posterior Part ◽  
Neural Basis ◽  
Attention Networks ◽  
The Core ◽  
Hierarchical Partition ◽  
Brain Fmri ◽  
The Brain

Finding the neural basis of consciousness is a challenging issue, and it is still inconclusive where the core of consciousness is distributed in the brain. The global neuronal workspace theory (GNWT) emphasizes the role of the frontoparietal regions, whereas the integrated information theory (IIT) argues that the posterior part of the brain is the core of consciousness. IIT has proposed “main complex” as the core of consciousness in a dynamic system, which is a set of elements that the information loss in a hierarchical partition approach is the largest among that of all its supersets and subsets. However, no experimental study has reported the core of consciousness using the main complex for actual brain activity. This study estimated the main complex of brain dynamics using a functional MRI. The whole-brain fMRI data of eight conditions (seven tasks and a rest state) were divided into multiple elements based on network atlases, and the main complex of the dynamic system was estimated for each condition. It is assumed that, if there is a set of elements in the complex that are common to all conditions, the set is likely to contain the core of consciousness. Executive control, salience, and dorsal/ventral attention networks were commonly included in the main complex across all conditions, implying that these networks are responsible for the core of consciousness. This finding is consistent with the GNWT, as these networks are across the prefrontal and parietal regions.

The gene serpent has homeotic properties and specifies endoderm versus ectoderm within the Drosophila gut

Development ◽  
1994 ◽  
Vol 120 (5) ◽  
pp. 1123-1135 ◽  
Author(s):  
R. Reuter
Keyword(s):  
Posterior Part ◽  
Posterior Region ◽  
Homeotic Gene ◽  
Gap Gene ◽  
Posterior Midgut ◽  
Endodermal Differentiation ◽  
Anterior Midgut

The gut of Drosophila consists of ectodermally derived foregut and hindgut and endodermally derived midgut. Here I show that the gene serpent plays a key role in the development of the endoderm. serpent embryos lack the entire midgut and do not show endodermal differentiation. They gastrulate normally and form proper amnioproctodeal and anterior midgut invaginations. However, the prospective anterior midgut cells acquire properties that are usually found in ectodermal foregut cells. In the posterior region of the embryo, the prospective posterior midgut forms an additional hindgut which is contiguous with the normal hindgut and which appears to be a serial duplication, not a mere enlargement of the hindgut. The fate shifts in both the anterior and the posterior part of the srp embryo can be described in terms of homeotic transformations of anterior midgut to foregut and of posterior midgut to hindgut. serpent appears to act as a homeotic gene downstream of the terminal gap gene huckebein and to promote morphogenesis and differentiation of anterior and posterior midgut.

Thalamic Relay Site for Cold Perception in Humans

1999 ◽  
Vol 81 (4) ◽  
pp. 1970-1973 ◽  
Author(s):  
Karen D. Davis ◽  
Andres M. Lozano ◽  
Marosh Manduch ◽  
Ronald R. Tasker ◽  
Zelma H. T. Kiss ◽  
...  
Keyword(s):  
Posterior Part ◽  
Body Part ◽  
Ventromedial Nucleus ◽  
Neural Pathways ◽  
Skin Area ◽  
Cold Sensation ◽  
Human Thalamus ◽  
Direct Demonstration ◽  
Thalamic Relay ◽  
Stimulation Of

  Thalamic relay site for cold perception in humans. The neural pathways subserving the sensation of temperature are virtually unknown. However, recent findings in the monkey suggest that the sensation of cold may be mediated by an ascending pathway relaying in the posterior part of the thalamic ventromedial nucleus (VMpo). To test this hypothesis we examined the responses of neurons to thermal stimulation of the skin and determined the perceptual effects of microstimulation in the VMpo region in awake patients undergoing functional stereotactic surgery. In 16 patients, microstimulation in the VMpo region evoked cold sensations in a circumscribed body part. Furthermore, at some of these sites thalamic neurons were found that responded to innocuous cooling of the skin area corresponding to the stimulation-evoked cold sensations. These data provide the first direct demonstration of a pathway mediating cold sensation and its location in the human thalamus.

Surface rupture and landscape response within the core of the great Mw 8.3 1934 earthquake mesoseismal area: the case of the Khutti Khola

2020 ◽  
Author(s):  
Magali Riesner ◽  
Laurent Bollinger ◽  
Magali Rizza ◽  
Yann Klinger ◽  
Soma Nath Sapkota ◽  
...  
Keyword(s):  
Potential Surface ◽  
Plate Boundary ◽  
Historical Earthquake ◽  
Surface Rupture ◽  
Alluvial Deposits ◽  
The Core ◽  
Landscape Response ◽  
Lateral Extent ◽  
Fault Trace ◽  
Colluvial Wedge

<p>Great earthquakes generated along the Himalayan mega-thrust plate boundary have been shown to rupture the surface. The Mw 8.3 1934 Bihar-Nepal earthquake is one of these major seismotectonic events. Previous studies focused on sites located at the western end of the fault trace concluded that the surface rupture associated with this earthquake is still locally preserved. Here we document a new site, along the Khutti Khola rivercut, in the core of the mesoseismal area. The effects of the earthquake in that area were described as cataclysmic, generating massive damages, landslides blocking one of the local rivers at 4 sites. The Khutti river cuts the frontal range, incising a 4 m- high cumulated scarp exposed along a 19 m-long stretch of Siwaliks claystone-sandstone and alluvial deposits. A detailed study of the river cut revealed the presence of faults emplacing Siwaliks over quaternary alluvials. These units are sealed by a colluvial wedge and wash as well as by recent underformed alluvials. The C14 radiocarbon analyses of 10 detrital charcoals collected reveal that the last surface-rupturing event at that site occurred after the 17<sup>th</sup> century and prior to the post-bomb deposition of the young alluvials. The only historical earthquake known within that period is the 1934 earthquake, inferring that for this event the rupture reached the surface at that site. The rupture was followed by rapid aggradation and sealed by ~2 meters of sediments. In addition to being another rare example for the preservation of the 1934 earthquake, these observations demonstrate that, despite their magnitude and potential surface rupture, the study of the great Himalayan paleo-earthquakes are still challenging however necessary to constrain their lateral extent.</p>

Microstimulation in the Region of the Human Thalamic Principal Somatic Sensory Nucleus Evokes Sensations Like Those of Mechanical Stimulation and Movement

2004 ◽  
Vol 91 (2) ◽  
pp. 736-745 ◽  
Author(s):  
Shinji Ohara ◽  
Nirit Weiss ◽  
Fred A. Lenz
Keyword(s):  
Relative Density ◽  
Mechanical Stimulation ◽  
Body Movement ◽  
Receptive Fields ◽  
Muscle Afferents ◽  
The Body ◽  
The Core ◽  
Sensory Nucleus ◽  
Stimulation Of

We explored the region of human thalamic somatic sensory nucleus (ventral caudal, Vc), corresponding to monkey ventral posterior (VP), with threshold microstimulation (TMIS) during stereotactic procedures for the treatment of tremor. Of 122 sites in 116 patients (124 thalami) where mechanical (touch, pressure, and sharp) or movement [movement through the body (movement) and vibration] sensations were evoked, 72 sites were found in the core or in adjacent regions, posterior-inferior (33), inferior (4), and posterior to the core (13). Sites where TMIS evoked touch were less frequently found in the core than those where movement or pressure sensations were evoked. Pressure was more commonly ( P < 0.05) evoked than vibration at sites where cells had intraoral receptive fields (RFs). Touch and vibration were more commonly ( P < 0.05) evoked than pressure at sites where cells had facial RFs, consistent with the relative density of rapidly adapting (RA) receptors in the mouth and face. Sites described as deep and movement were found superior and anterior in the core, consistent with the location of cells responding to stimulation of muscle afferents. At 72 of 122 sites, TMIS evoked the same sensation at two or more sites in the same plane. Of these sites, 58 are adjacent to each other, in a cluster, consistent with studies of the localization of cells responding to different modalities. These results demonstrate that mechanical and movement sensations can be evoked by stimulation in the region of Vc. The characteristics of these sites suggest that the sensations are evoked by stimulation of pathways specific to cutaneous and deep mechanoreceptors.

Physiological study of presumed ventralis intermedius neurons in the human thalamus

1979 ◽  
Vol 50 (3) ◽  
pp. 290-297 ◽  
Author(s):  
Chihiro Ohye ◽  
Hirotaro Narabayashi
Keyword(s):  
Electrical Stimulation ◽  
Receptive Field ◽  
Active Movement ◽  
Spike Discharge ◽  
Content Type ◽  
Neural Noise ◽  
Tactile Stimuli ◽  
Human Thalamus ◽  
Sensory Nucleus ◽  
Fine Print

✓ Unitary or a group of unitary responses recorded extracellularly in the rostral part of the thalamic sensory nucleus during the course of thalamotomy for parkinsonian and other kinds of tremor were studied. They were the first sensory neurons encountered in the frontocaudal approach of the stereotaxic needle to the therapeutic target at the lower border of the ventralis intermedius nucleus. The spike discharges, isolated from high neural noise background, responded to passive and/or active movement of joint or muscle on the contralateral extremity but never to light tactile stimuli. In five cases, electrical stimulation of the corresponding peripheral nerves elicited the same spike discharge at short and fixed latency of about 12 msec. Weak electrical stimulation given to each thalamic point produced paresthetic or electric sensation around the receptive field, and stronger stimulation induced tremor-like movement in the area involving the receptive field. Finally, a small coagulation lesion in this thalamic point resulted in immediate relief of tremor without any sensory deficit. From these findings, the possibility is considered that in the human, this particular thalamic zone could be the ventralis intermedius nucleus, which is separable from the surrounding nuclei and is related to tremor mechanism.

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