Association of decrease in insula fMRI activation with changes in trait anxiety in patients with craniomandibular disorder (CMD).

Patients with chronic pain and especially with craniomandibular disorder (CMD) show specific psychopathology in trait anxiety. In a previous longitudinal functional imaging study on CMD we found that the anterior insula was modulated by successful therapy intervention and pain relief. We here intended to investigate possible associations between anterior insula fMRI-activation during occlusal movements and trait anxiety over a splint therapy approach in patients with CMD. Three fMRI-investigations of a craniomandibular occlusion task were performed together with pain score evaluations and scoring of trait anxiety (State -Trait Anxiety Inventory; STAI) before, after two weeks and after three months of a DIR-mandibular splint therapy in a small group (n = 9) of CMD patients. Patients showed increased anxiety levels before therapy assessed with the STAI and the depression and anxiety scale (DASS). Besides of relevant reduction in pain the STAI decreased over time. Reduction in STAI was associated with anterior insular fMRI-activation reduction on both hemispheres. We conclude that the anxiety driven anticipation of pain related to occlusal trigger is processed in the anterior insula and might therefore be a main driver of therapeutic intervention by the splint therapy in CMD.

Behavioral demonstration of a somatosensory neuroprosthesis.

Tactile sensation is critical for effective object manipulation, but current prosthetic upper limbs make no provision for delivering somesthetic feedback to the user. For individuals who require use of prosthetic limbs, this lack of feedback transforms a mundane task into one that requires extreme concentration and effort. Although vibrotactile motors and sensory substitution devices can be used to convey gross sensations, a direct neural interface is required to provide detailed and intuitive sensory feedback. In light of this, we describe the implementation of a somatosensory prosthesis with which we elicit, through intracortical microstimulation (ICMS), percepts whose magnitude is graded according to the force exerted on the prosthetic finger. Specifically, the prosthesis consists of a sensorized finger, the force output of which is converted into a regime of ICMS delivered to primary somatosensory cortex through chronically implanted multi-electrode arrays. We show that the performance of animals (Rhesus macaques) on a tactile task is equivalent whether stimuli are delivered to the native finger or to the prosthetic finger.

The representation of stimulus orientation in the early stages of somatosensory processing.

At an early stage of processing, a stimulus is represented as a set of contours. In the representation of form, a critical feature of these local contours is their orientation. In the present study, we investigate the representation of orientation at the somatosensory periphery and in primary somatosensory cortex. We record the responses of mechanoreceptive afferents and of neurons in areas 3b and 1 to oriented bars and edges using a variety of stimulus conditions. We find that orientation is not explicitly represented in the responses of single afferents, but a large proportion of orientation detectors (approximately 50%) can be found in areas 3b and 1. Many neurons in both areas exhibit orientation tuning that is preserved across modes of stimulus presentation (scanned vs indented) and is relatively insensitive to other stimulus parameters, such as amplitude and speed, and to the nature of the stimulus, bar or edge. Orientation-selective neurons tend to be more SA (slowly adapting)-like than RA (rapidly adapting)-like, and the strength of the orientation signal is strongest during the sustained portion of the response to a statically indented bar. The most orientation-selective neurons in SI are comparable in sensitivity with that measured in humans. Finally, responses of SI neurons to bars and edges can be modeled with a high degree of accuracy using Gaussian or Gabor filters. The similarity in the representations of orientation in the visual and somatosensory systems suggests that analogous neural mechanisms mediate early visual and tactile form processing.

The neural coding of stimulus intensity: linking the population response of mechanoreceptive afferents with psychophysical behavior.

How specific aspects of a stimulus are encoded at different stages of neural processing is a critical question in sensory neuroscience. In the present study, we investigated the neural code underlying the perception of stimulus intensity in the somatosensory system. We first characterized the responses of SA1 (slowly adapting type 1), RA (rapidly adapting), and PC (Pacinian) afferents of macaque monkeys to sinusoidal, diharmonic, and bandpass noise stimuli. We then had human subjects rate the perceived intensity of a subset of these stimuli. On the basis of these neurophysiological and psychophysical measurements, we evaluated a series of hypotheses about which aspect(s) of the neural activity evoked at the somatosensory periphery account for perception. We evaluated three types of neural codes. The first consisted of population codes based on the firing rate of neurons located directly under the probe. The second included population codes based on the firing rate of the entire population of active neurons. The third included codes based on the number of active afferents. We found that the response evoked in the localized population is logarithmic with stimulus amplitude (given a constant frequency composition), whereas the population response across all neurons is linear with stimulus amplitude. We conclude that stimulus intensity is best accounted for by the firing rate evoked in afferents located under or near the locus of stimulation, weighted by afferent type.

[Are children properly classified within the scope of expert assessment to determine need for services?]. / Werden Kinder im Rahmen der Begutachtung zur Bestimmung von Pflegebedürftigkeit richtig eingestuft?

This project deals with assessment directives issued by the leading statutory care insurance companies to define the need for care of children at certain ages in coping with the activities of daily life specified by the German Social Legislation. The ages in question relate to healthy, normally developed children. They are used as a measure of comparison for the assessment of diseased children. Besides, they have a decisive significance in defining the need for care. Only if a child is not able to perform a certain activity, although it is meant to be able to do so at that age, can we define the need for help and assistance, i.e. care. The project is divided into two sections. 1. Comparison of age mentioned in the assessment directives for each of the daily life activities of healthy and normally developed children aged 1 to 12 years with the age mentioned in technical literature. 2. Comparison of age mentioned in the assessment directives for each ot the daily life activities of healthy and normally developed children at the age of 1 to 12 years with those mentioned in retrospective interviews with the same group of children. In the first part of the project, an analysis of the literature dealing with the subject was done. The literature included the stock of technical literature in the German language. Studying the literature, ages for children could be isolated, that could be classed with the activities of daily life mentioned in the German Social Code. These ages were compared with those in the assessment directives. In a second part of the project, 81 mothers and fathers of healthy, normally developed children aged 1 to 12 years were asked via a questionnaire. They were asked to estimate retrospectively from what age on their child had been able to perform certain activities of daily life without any help. The comparison of ages mentioned in the assessment directives with those of the analysis of literature conformed only regarding daily life activity. Regarding the other activities of daily life the age for children was set higher in the assessment directives than in the literature. Comparing the age of children in the assessment directives with the results of the questionnaires the age was also set higher in the directives than shown by the results of the questionnaires. The results of the literature analysis and the inquiry by questionnaires show that the ages mentioned in the assessment directives for an independent performance of daily life activities do not correspond to the development according to the age of healthy normally developed children aged 1 to 12 years. As a result of this project it seems to be justified to be doubtful about an adequate assessment of children who are in the need of care. Due to this reason it would be desirable to reexamine the data of the assessment directives by means of a new representative prospective study.

Reflections on the evolution of cardiopulmonary bypass.

The concept of cardiopulmonary bypass is more than a century old. Although the first clinical application occurred in 1953, there were great deficits in knowledge and materials that had to be overcome before we could achieve the outcomes of cardiac surgery that we have today.

Left ventricular hyperkinesia at rest and during exercise in normotensive patients 2 to 27 years after coarctation repair.

The short- and long-term results of effective surgical repair of coarctation of the aorta on left ventricular mass and function in 48 patients were evaluated using echocardiography and stress-gated radionuclide angiography. Thirty-two of the 48 patients who had no additional cardiac problems and had technically adequate radionuclide angiograms form the basis for this report. Among these, three had mild systolic hypertension and none had significant aortic valve dysfunction. Age at the time of study ranged from 6.5 to 59 years (mean 27). Age at the time of surgery ranged from 3 months to 34 years (mean 12 years). Duration from surgery to the time of noninvasive study ranged from 2 to 29 years (mean 15). In the 32 patients, left ventricular mass was 120 +/- 20 g/m2, compared with a control value of 87 +/- 10 g/m2. Mean left ventricular ejection fraction was elevated to 69.2 +/- 1.6% at rest (control 60 +/- 1.3%) and 78.8 +/- 1.3% during exercise (control 70 +/- 1.7%) (p less than 0.01). The systolic ejection rate was significantly increased (p less than 0.01) and end-systolic volume significantly decreased (p less than 0.01) compared with values in control patients. There was no correlation between ejection fraction and either age at the time of surgery or years since surgery. These findings of hyperdynamic left ventricular function and increased left ventricular mass without apparent cause many years after coarctation repair raise important questions as to mechanisms, extension to other forms of afterload stress that have been surgically or medically relieved and long-term outcome.

PEEP: its use in young patients with apparently normal lungs.

PEEP has been advocated for use in patients with the acute respiratory distress syndrome characterized by a marked reduction in FRC. It has not been advocated for patients with apparently normal lungs requiring prolonged mechanical ventilation. We have done inert gas washouts on five young patients comparing no PEEP to 10 cm H2O PEEP. Four of the five showed a significant improvement in PaO2, a decrease in AaDO2 and Qs/Qt, the fifth a slight improvement on PEEP. Arterial washouts were significantly faster on PEEP in all patients suggesting a decrease in intrapulmonary shunting. Airway washouts in the initial phase were faster off PEEP suggesting an increase in lung volume and FRC with PEEP. Later portions of the curve were faster on PEEP suggesting improved distribution of ventilation. These findings suggest that PEEP might be of significant value in treatment of patients requiring prolonged mechanical ventilation for reasons other than lung abnormalities.

Optimal flow pattern for mechanical ventilation of the lungs. 2. The effect of a sine versus square wave flow pattern with and without an end-inspiratory pause on patients.

In four series of patients, the efficiency of ventilation of a sine wave without an end-inspiratory pause was compared to a square wave without a pause, a sine wave with a pause to a square wave with a pause, a sine wave to a sine wave with a pause, and a sine wave with a long pause to one with a short pause. The primary mode of evaluation was through simultaneous airway and arterial argon washout curves. Additional cardiopulmonary measurements were made. Results indicate: (1) a statistically significant improvement in ventilation with a sine wave with a pause; (2) a statistically significant improvement with the longer pause as compared to the short pause.

Optimal flow pattern for mechanical ventilation of the lungs. Evaluation with a model lung.

The major components entering into the inspiratory pattern of various respirators were tested on a model lung which had an abnormally high airway resistance on one side. The tests consisted of simultaneous nitrogen washout curves from each lung separately utilizing two mass spectrometers. The components tested included a constant versus accelerating wave form and the presence, duration or absence of an end-inspiratory pause. Respirators tested included the Bennett MA1. Engström 300 and the Elema Schonander Servo tventilator 900. The results demonstrated the importance of an end inspiratory pause in improving gas distribution and efficiency of washout. No difference was found between a constant or accelerating air flow. Preliminary results in man appear to confirm the importance of an end inspiratory pause.