Correlations between EEG and intestinal electrical stimulation

Many diseases affect the autonomous nervous system and the central nervous system simultaneously, for example Parkinson’s disease or irritable bowel syndrome. To study neurophysiologic interactions between the intestinal electrical activity and the electroencephalography (EEG) pattern of the brain, we combined intestinal electrical stimulation (IES) and non-invasive telemetric full-band DC EEG recordings in an acute pig-model. Intestinal motility was monitored with accelerometers. Brain activity was analyzed with regard to network driven phenomena like phase amplitude coupling (PAC) within two time-windows: 1 min after IES (early response) and 3 min after stimulation (late response). Here we present the results for two stimulation sites (small intestine, colon) and two parietal scalp-EEG channels (right and left somatosensory cortex region). Electrical stimulation consisted of a 30 or 130 Hz pulse. In summary, the PAC modulation index at a parietal EEG recording position is decreased after IES. This effect is in line with an inhibitory effect of our IES protocol regarding peristalsis. The surprisingly strong effects of IES on network driven EEG patterns may be translated into new therapeutic techniques and/or diagnostic tools in the future. Furthermore, analytic tools, operating on sparse datasets, may be ideally suited for the integration in implantable intestinal pacemakers as feedback system.Peer Reviewe

Toward Miniaturized Low-Power Solutions for Intestinal Implants

Intestinal electrical stimulation via implants is already used to treat several disorders like constipation or incontinence. Stimulation parameters are most often empiric and not based on systematic studies. One prerequisite to evaluate effects of intestinal electrical stimulation is a direct assessment of intestinal motility. Some common methods are strain gauge transducers or manometry. With both the methods, it is not possible to record the exact 3-D movement. Therefore, we established a new method to record gastrointestinal motility with ultraminiaturized accelerometers, directly glued to the outer surface of the stomach, small intestine, and colon. With this technique, we were able to record precise local motility changes after electrical stimulation. Due to the low energy demand and the small size of the system, it is potentially useful for chronic measurements at multiple sites of the intestinal tract. We will present our first results regarding stimulation-dependent motility changes using up to eight implanted accelerometers in an acute pig model

Models for preterm cortical development using non invasive clinical EEG

The objective of this study was to evaluate the piglet and the mouse as model systems for preterm cortical development. According to the clinical context, we used non invasive EEG recordings. As a prerequisite, we developed miniaturized Ag/AgCl electrodes for full band EEG recordings in mice and verified that Urethane had no effect on EEG band power. Since mice are born with a “preterm” brain, we evaluated three age groups: P0/P1, P3/P4 and P13/P14. Our aim was to identify EEG patterns in the somatosensory cortex which are distinguishable between developmental stages and represent a physiologic brain development. In mice, we were able to find clear differences between age groups with a simple power analysis of EEG bands and also for phase locking and power spectral density. Interhemispheric coherence between corresponding regions can only be seen in two week old mice. The canolty maps for piglets as well as for mice show a clear PAC (phase amplitude coupling) pattern during development. From our data it can be concluded that analytic tools relying on network activity, as for example PAC (phase amplitude coupling) are best suited to extract basic EEG patterns of cortical development across species

Entscheidungen, Drogen und lokale Feldpotentiale

The honeybee Apis mellifera is a eusocial insect. Only the queen and the drones are involved in sexual reproduction. The female worker bees show age related caste differentiation. Young bees are doing indoor works whereas older bees are flying outside the hive to collect pollen and nectar. Caste differentiation is regulated by diverse mechanisms, including biogenic amines and the distribution of receptors which are targets for neurohormones and neurotransmitters. Despite differences in the neurotransmitter system of insects (for example octopamine instead of noradrenalin) drugs like cocaine or methylphenidate, which are dopamine reuptake inhibitors in vertebrates, have similar behavioral and neural effects in bees as in vertebrates. Several comparative studies give rising evidence for the view, that basic concepts are conserved among protostomian and deuterostomian animals. The vertebrate pallium and the annelidan mushroom body develop from the same, molecularly defined subregion, octopaminergic reward neurons are resembling the properties of ventral tegmental dopaminergic neurons in the vertebrate brain and there are striking similarities in the molecular basis of learning and memory. Therefore it is not surprising that ripple-like potentials and replay are occuring in hymenopteran insects during virtual and real navigation. And most likely also in the last common ancestor of deutrostomes and protostomes, some 600 million years ago. Ripples might have a slightly differnt appearance in insects than in rodents but they are clearly associated with navigation and associated high frequency of place related firing neurons. This is an overwhelming evidence for the occurence of cognitive maps in insects, which have often been considered to be unnessesary to describe the insects navigational needs and therefore recognized as anti parsimonious.Die Honigbiene Apis mellifera ist ein eusoziales Insekt. Nur die Königin und die Drohnen sind an der sexuellen Fortpflanzung beteiligt. Weibliche Arbeitsbienen zeigen altersabhängige Kastendifferenzierung. Junge Bienen arbeiten im Stock, z.B. als Ammenbienen, wogegen ältere Bienen ausschwärmen um Nektar und Pollen zu sammeln. Die Kastendetermination unterliegt einer komplexen Regelung, u.a. durch biogene Amine und die Verteilung von Rezeptoren, die Ziel von Neurohormonen und Pheromonen sind. Trotz Unterschieden im Neurotransmitterhaushalt der Insekten (Oktopamin anstelle von Noradrenalin), haben Drogen wie Ritalin und Kokain, die Dopamintransporter in Vertebraten blockieren, ähnliche Effekte in Bienen, wie in Vertebraten.Vergleichende Studien geben vielseitige Hinweise auf konservierte, basale Mechanismen in Deuterostomiern und Protostomiern. Das Pallium der Vertebraten und der Pilzkörper der Anneliden entwickeln sich aus der gleichen, molekular definierten Untereinheit, octopaminerge Belohnungsneurone ersetzen dopaminerge Neurone im ventralen Tegmentum der Vertebraten und die molekularen Grundlagen von Lernen und Gedächtnis weisen deutliche Ähnlichkeiten auf. Aus dieser Perspektive ist es nicht verwunderlich, dass ripple-ähnliche Potentiale und replay während virtueller und realer Navigation in Hymenopteren auftreten. Höchstwahrscheinlich gab es diese Potentiale bereits im Gehirn der letzten gemeinsamen Vorfahren von Protostomiern und Deuterostomiern, vor 600 Millionen Jahren. Ripples mögen in Insekten einige abweichende Charakteristika als in Nagern aufweisen, sie sind jedoch klar mit hochfrequenten Phasen von Ortsneuronen gekoppelt und treten während virtueller und realer Navigation auf. Dieses Ergebnis ist ein deutlicher Hinweis auf kognitive Karten in Insekten, auch wenn dies in der Vergangenheit oft als nicht notwendige Annahme zur Erklärung der Navigationsleistungen von Insekten betrachtet wurde und somit als Verstoß gegen das Parsimonieprinzip gewertet wurde

Confocal images of protocerebro calycal tract neurons colocalized with GABA and GAD immunostaining in Apis mellifera

<p>Confocal images (Leica TCS SP2), scan mode xyz, format 1024x1024, beam expander 6, pinhole 1, 40 x oil immersion objective (400 times magnification, plus digital zoom in some cases, see leica info files (txt)) of the mushroom body of the bee brain, including somata (So), pedunculus (Ped), calyx (Cal) and alpha lobe (aLob). Immunostaining was against GABA and GAD and Neurobiotin was used for intracellular staining. Filenames include the series index (n) and the date (associated number).</p

Light-cured polymer electrodes for non-invasive EEG recordings

Abstract We invented the first non-metallic, self-adhesive and dry biosignalling electrode. The PEDOT polymer electrode changes its aggregate state and conductivity by a light curing procedure. The electrode can be applied as a gel underneath hair without shaving. With the aid of blue light, the electrode can be hardened within a few seconds at the desired location on the scalp. The cured polymer electrode is highly conductive and can be applied on a very small location. Unlike other EEG electrodes, our electrode does not lose conductivity upon drying. Furthermore, our electrode strongly bonds to skin and does not require any additional adhesive. Short circuits due to an outflow of gel are prevented with this technique. Therefore, the PEDOT polymer electrode is extremely well suited for applications that, up to now, have been challenging, such as non-invasive EEG recordings from awake and freely moving animals, EEG recordings from preterm babies in the neonatal intensive care unit or long-term recordings in the case of sleep monitoring or epilepsy diagnostics. We addressed two technical questions in this work. First, is the EEG recorded with polymer electrodes comparable to a standard EEG? Second, is it possible to record full-band EEGs with our electrodes

EEG based assessment of stress in horses

As has been hypothesized more than 20 years ago, data derived from Electroencephalography (EEG) measurements can be used to distinguish between behavioral states associated with animal welfare. In our current study we found a high degree of correlation between the modulation index of phase related amplitude changes in the EEG of horses (n = 6 measurements with three different horses, mare and gelding) and their facial expression, measured by the use of the horse grimace scale. Furthermore, the pattern of phase amplitude coupling (PAC) was significantly different between a rest condition and a stress condition in horses. This pilot study paves the way for a possible use of EEG derived PAC as an objective tool for the assessment of animal welfare. Beyond that, the method might be useful to assess welfare aspects in the clinical setting for human patients, as for example in the neonatal intensive care unit.Peer Reviewe

Models for preterm cortical development using non invasive clinical EEG

The objective of this study was to evaluate the piglet and the mouse as model systems for preterm cortical development. According to the clinical context, we used non invasive EEG recordings. As a prerequisite, we developed miniaturized Ag/AgCl electrodes for full band EEG recordings in mice and verified that Urethane had no effect on EEG band power. Since mice are born with a “preterm” brain, we evaluated three age groups: P0/P1, P3/P4 and P13/P14. Our aim was to identify EEG patterns in the somatosensory cortex which are distinguishable between developmental stages and represent a physiologic brain development. In mice, we were able to find clear differences between age groups with a simple power analysis of EEG bands and also for phase locking and power spectral density. Interhemispheric coherence between corresponding regions can only be seen in two week old mice. The canolty maps for piglets as well as for mice show a clear PAC (phase amplitude coupling) pattern during development. From our data it can be concluded that analytic tools relying on network activity, as for example PAC (phase amplitude coupling) are best suited to extract basic EEG patterns of cortical development across species