Institute of Medical Psychology

München, Germany

Institute of Medical Psychology

München, Germany

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News Article | May 17, 2017
Site: www.sciencedaily.com

Electrical stimulation of the brain by applying current to the eye may help retinal nerve cells to survive injury. While these neurons may not be restored to full function, they are prevented from dying. But to achieve survival, their interconnections, the dendritic tree, needs to disconnect rapidly for the protective action to unfold. In a study published in Scientific Reports, researchers from Magdeburg University (Germany) and The Chinese University of Hong Kong report that for rats and mice, repetitive transorbital alternating current stimulation (rtACS) may help preserve visual neurons from cell death after injury. Because the tissue at the back of the eye, the retina, is part of the brain, researchers can directly observe how brain cells react in the living animal. The researchers repeatedly monitored neurons in both rat and mouse retinas after an optic nerve injury and measured neuronal death after this lesion. Surprisingly, a neuroprotective treatment with electrical alternating current stimulation increased cellular survival in the eye´s retina, but it also induced a fast and complete stripping-off of the neuron's dendritic tree. The dendrites are like a tree receiving many thousands of signals from other neurons. This enables them to process visual information and then transmit the signals along the optic nerve towards the brain. By retracting its dendrites, the cell withdraws itself from this intercellular communication network and becomes silent -- which helps its survival. The test animals were divided into groups and subjected to both real and sham treatments. For the rats, optic nerve crush (ONC) was used to induce an injury in some of the animals to mimic glaucoma. Some animals and not others (sham) were treated with rtACS, resulting in three test groups: ONC/rtACS, ONC/Sham, and Sham/Sham. Using in vivo confocal neuroimaging (ICON) and measurements of Visual Evoked Potentials (VEP), the researchers could determine whether a neuron had survived and whether it was still functioning. The ONC and the first rtACS stimulation were done on day zero. ICON was performed on day 4, followed by rtACS or sham stimulation. On day 7 post ONC another ICON was performed. For the mice, a confocal laser ophthalmoscope was used to image the dendritic structures of the retina for three groups of subjects, ONC/rtACS, ONC/Sham and Sham/rtACS. The mice received rtACS on days 0, 3, 6, 9 and 12 after ONC and images were taken on days 3, 7 and 14. According to lead author Petra Henrich-Noack, PhD, Institute of Medical Psychology, Otto-von-Guericke University, Magdeburg, Germany, "With our experiments, we have detected so far unknown 'silent survivor cells' in the brain and it will be exciting to find out whether they later die or can be reactivated." Surprisingly, neurons in the retina of animals that survived better when treated with rtACS lost their dendritic tree completely within the first 3 days after the lesion. The authors suggest that this early structural isolation might protect the neurons from the "toxic" excitation that is known to appear soon after brain damage.


News Article | May 17, 2017
Site: www.eurekalert.org

Magdeburg, Germany and Hongkong, China. May 17, 2017 - Electrical stimulation of the brain by applying current to the eye may help retinal nerve cells to survive injury. While these neurons may not be restored to full function, they are prevented from dying. But to achieve survival, their interconnections, the dendritic tree, needs to disconnect rapidly for the protective action to unfold. In a study published in Scientific Reports, researchers from Magdeburg University (Germany) and The Chinese University of Hong Kong report that for rats and mice, repetitive transorbital alternating current stimulation (rtACS) may help preserve visual neurons from cell death after injury. Because the tissue at the back of the eye, the retina, is part of the brain, researchers can directly observe how brain cells react in the living animal. The researchers repeatedly monitored neurons in both rat and mouse retinas after an optic nerve injury and measured neuronal death after this lesion. Surprisingly, a neuroprotective treatment with electrical alternating current stimulation increased cellular survival in the eye´s retina, but it also induced a fast and complete stripping-off of the neuron's dendritic tree. The dendrites are like a tree receiving many thousands of signals from other neurons. This enables them to process visual information and then transmit the signals along the optic nerve towards the brain. By retracting its dendrites, the cell withdraws itself from this intercellular communication network and becomes silent - which helps its survival. The test animals were divided into groups and subjected to both real and sham treatments. For the rats, optic nerve crush (ONC) was used to induce an injury in some of the animals to mimic glaucoma. Some animals and not others (sham) were treated with rtACS, resulting in three test groups: ONC/rtACS, ONC/Sham, and Sham/Sham. Using in vivo confocal neuroimaging (ICON) and measurements of Visual Evoked Potentials (VEP), the researchers could determine whether a neuron had survived and whether it was still functioning. The ONC and the first rtACS stimulation were done on day zero. ICON was performed on day 4, followed by rtACS or sham stimulation. On day 7 post ONC another ICON was performed. For the mice, a confocal laser ophthalmoscope was used to image the dendritic structures of the retina for three groups of subjects, ONC/rtACS, ONC/Sham and Sham/rtACS. The mice received rtACS on days 0, 3, 6, 9 and 12 after ONC and images were taken on days 3, 7 and 14. According to lead author Petra Henrich-Noack, PhD, Institute of Medical Psychology, Otto-von-Guericke University, Magdeburg, Germany, "With our experiments, we have detected so far unknown 'silent survivor cells' in the brain and it will be exciting to find out whether they later die or can be reactivated." Surprisingly, neurons in the retina of animals that survived better when treated with rtACS lost their dendritic tree completely within the first 3 days after the lesion. The authors suggest that this early structural isolation might protect the neurons from the "toxic" excitation that is known to appear soon after brain damage. Co-author Christopher Kai-Shun Leung, MD, of The Chinese University of Hong Kong, adds, "Although we could see the surviving neuronal cells when looking with an adapted microscope through the eye to the retina, the lesion was apparently too severe to detect any improvement in visual function, which was observed after a similar kind of stimulation in glaucoma patients at the chronic stage". Co-investigator Bernhard A. Sabel, PhD, Director of the Institute of Medical Psychology, Otto-von-Guericke University, Magdeburg, Germany, notes that rtACS is being used successfully in a clinical setting for the treatment of vision loss. The Magdeburg group has been looking into the effects of non-invasive brain stimulation via the eye for many years. Several studies with patients suffering from vision impairments demonstrated that rtACS is a successful strategy for rehabilitation months and years after the damage had appeared, leading to significantly improved visual abilities. But he notes that more work needs to be done to better understand the mechanisms of brain stimulation in patients with vision loss.


Vedder A.,Ludwig Maximilians University of Munich | Vedder A.,Institute of Sociology | Vedder A.,Institute of Medical Psychology | Vedder A.,Parmenides Center for Art and Science | And 18 more authors.
PLoS ONE | Year: 2015

This study capitalizes on individual episodic memories to investigate the question, how different environments affect us on a neural level. Instead of using predefined environmental stimuli, this study relied on individual representations of beauty and pleasure. Drawing upon episodic memories we conducted two experiments. Healthy subjects imagined pleasant and non-pleasant environments, as well as beautiful and non-beautiful environments while neural activity was measured by using functional Magnetic Resonance Imaging. Although subjects found the different conditions equally simple to visualize, our results revealed more distribut-ed brain activations for non-pleasant and non-beautiful environments than for pleasant and beautiful environments. The additional regions activated in non-pleasant (left lateral prefrontal cortex) and non-beautiful environments (supplementary motor area, anterior cortical midline structures) are involved in self-regulation and top-down cognitive control. Taken together, the results show that perceptual experiences and emotional evaluations of environments within a positive and a negative frame of reference are based on distinct patterns of neural activity.We interpret the data in terms of a different cognitive and processing load placed by exposure to different environments. The results hint at the efficiency of subject-generated representations as stimulus material. © 2015 Vedder et al.


Eelderink-Chen Z.,Chromatin | Olmedo M.,Institute of Medical Psychology | Bosman J.,Groningen Research Institute of Pharmacy | Merrow M.,Institute of Medical Psychology
Methods in Enzymology | Year: 2015

Three properties are most often attributed to the circadian clock: a ca. 24-h free-running rhythm, temperature compensation of the circadian rhythm, and its entrainment to zeitgeber cycles. Relatively few experiments, however, are performed under entrainment conditions. Rather, most chronobiology protocols concern constant conditions. We have turned this paradigm around and used entrainment to study the circadian clock in organisms where a free-running rhythm is weak or lacking. We describe two examples therein: Caenorhabditis elegans and Saccharomyces cerevisiae. By probing the system with zeitgeber cycles that have various structures and amplitudes, we can demonstrate the establishment of systematic entrained phase angles in these organisms. We conclude that entrainment can be utilized to discover hitherto unknown circadian clocks and we discuss the implications of using entrainment more broadly, even in model systems that show robust free-running rhythms. © 2015 Elsevier Inc. All rights reserved.


PubMed | Institute of Medical Psychology
Type: | Journal: Methods in enzymology | Year: 2015

Three properties are most often attributed to the circadian clock: a ca. 24-h free-running rhythm, temperature compensation of the circadian rhythm, and its entrainment to zeitgeber cycles. Relatively few experiments, however, are performed under entrainment conditions. Rather, most chronobiology protocols concern constant conditions. We have turned this paradigm around and used entrainment to study the circadian clock in organisms where a free-running rhythm is weak or lacking. We describe two examples therein: Caenorhabditis elegans and Saccharomyces cerevisiae. By probing the system with zeitgeber cycles that have various structures and amplitudes, we can demonstrate the establishment of systematic entrained phase angles in these organisms. We conclude that entrainment can be utilized to discover hitherto unknown circadian clocks and we discuss the implications of using entrainment more broadly, even in model systems that show robust free-running rhythms.


Juda M.,Institute of Medical Psychology | Juda M.,University of British Columbia | Vetter C.,Institute of Medical Psychology | Roenneberg T.,Institute of Medical Psychology
Journal of Biological Rhythms | Year: 2013

Sleep is systematically modulated by chronotype in day-workers. Therefore, investigations into how shift-work affects sleep, health, and cognition may provide more reliable insights if they consider individual circadian time (chronotype). The Munich ChronoType Questionnaire (MCTQ) is a useful tool for determining chronotype. It assesses chronotype based on sleep behavior, specifically on the local time of mid-sleep on free days corrected for sleep debt accumulated over the workweek (MSFsc). Because the original MCTQ addresses people working standard hours, we developed an extended version that accommodates shift-work (MCTQShift). We first present the validation of this new version with daily sleep logs (n = 52) and actimetry (n = 27). Next, we evaluated 371 MCTQShift entries of shift-workers (rotating through 8-h shifts starting at 0600 h, 1400 h, and 2200 h). Our results support experimental findings showing that sleep is difficult to initiate and to maintain under the constraints of shift-work. Sleep times are remarkably stable on free days (on average between midnight and 0900 h), so that chronotype of shift-workers can be assessed by means of MSF - similar to that of day-workers. Sleep times on free-days are, however, slightly influenced by the preceding shift (displacements <1 h), which are smallest after evening shifts. We therefore chose this shift-specific mid-sleep time (MSFE) to assess chronotype in shift-workers. The distribution of MSFE in our sample is identical to that of MSF in day-workers. We propose conversion algorithms for chronotyping shift-workers whose schedules do not include free days after evening shifts. © 2013 The Author(s).


Shao S.-H.,Institute of Medical Psychology | Shi S.-S.,Institute of Medical Psychology | Li Z.-L.,Institute of Biochemistry and Molecular Biology | Zhao M.-S.,Binzhou Medical College | And 2 more authors.
Chinese Journal of Physiology | Year: 2010

Brain-derived neurotrophins factor (BDNF) belongs to the neurotrophins family which acts on neuronal survival and growth and has been associated with cognition process. TrkB is the primary signal transduction receptor for BDNF. In the present study, hippocampal BDNF and TrkB mRNA were detected by RT-PCR in 2- and 22-month rats, respectively, which were exposed to different durations of mild stress protocol of 8-day, 21-day and 28-day chronic unpredictable mild stress (CUMS). Observation of exploratory behavior in an open field (OF) test indicated stress levels and changes of spontaneous activity. We demonstrated that CUMS induced decrease of BDNF mRNA in two aged groups, but the increase change of TrkB mRNA compared with those of the control groups. Moreover, the changes of BDNF mRNA and TrkB mRNA measured in both the 21-day and 28-day stress groups represent obvious decrease than those of the 8-day stress groups, and the expression examined in young groups appeared to be higher than those of the aged group, especially in the 28-day stress groups. Results of OF test showed that explicit behaviors in two age groups decreased gradually with the process of stress revealing a depressive state under the stress condition. Meanwhile, the behaviors of young rats seemed to be more active than those of the aged rats, exhibiting weak adaptation to the stress. The study suggested that stress paradigm and aging certainly had effect on the regulation of BDNF mRNA and TrkB mRNA which might be related to damage and protection function of the hippocampus. © 2010 by The Chinese Physiological Society and Airiti Press Inc.


PubMed | Institute of Medical Psychology
Type: Journal Article | Journal: The Chinese journal of physiology | Year: 2011

Brain-derived neurotrophins factor (BDNF) belongs to the neurotrophins family which acts on neuronal survival and growth and has been associated with cognition process. TrkB is the primary signal transduction receptor for BDNF. In the present study, hippocampal BDNF and TrkB mRNA were detected by RT-PCR in 2- and 22-month rats, respectively, which were exposed to different durations of mild stress protocol of 8-day, 21-day and 28-day chronic unpredictable mild stress (CUMS). Observation of exploratory behavior in an open field (OF) test indicated stress levels and changes of spontaneous activity. We demonstrated that CUMS induced decrease of BDNF mRNA in two aged groups, but the increase change of TrkB mRNA compared with those of the control groups. Moreover, the changes of BDNF mRNA and TrkB mRNA measured in both the 21-day and 28-day stress groups represent obvious decrease than those of the 8-day stress groups, and the expression examined in young groups appeared to be higher than those of the aged group, especially in the 28-day stress groups. Results of OF test showed that explicit behaviors in two age groups decreased gradually with the process of stress revealing a depressive state under the stress condition. Meanwhile, the behaviors of young rats seemed to be more active than those of the aged rats, exhibiting weak adaptation to the stress. The study suggested that stress paradigm and aging certainly had effect on the regulation of BDNF mRNA and TrkB mRNA which might be related to damage and protection function of the hippocampus.


PubMed | Institute of Medical Psychology
Type: Journal Article | Journal: Journal of biological rhythms | Year: 2013

Sleep is systematically modulated by chronotype in day-workers. Therefore, investigations into how shift-work affects sleep, health, and cognition may provide more reliable insights if they consider individual circadian time (chronotype). The Munich ChronoType Questionnaire (MCTQ) is a useful tool for determining chronotype. It assesses chronotype based on sleep behavior, specifically on the local time of mid-sleep on free days corrected for sleep debt accumulated over the workweek (MSFsc). Because the original MCTQ addresses people working standard hours, we developed an extended version that accommodates shift-work (MCTQ(Shift)). We first present the validation of this new version with daily sleep logs (n = 52) and actimetry (n = 27). Next, we evaluated 371 MCTQ(Shift) entries of shift-workers (rotating through 8-h shifts starting at 0600 h, 1400 h, and 2200 h). Our results support experimental findings showing that sleep is difficult to initiate and to maintain under the constraints of shift-work. Sleep times are remarkably stable on free days (on average between midnight and 0900 h), so that chronotype of shift-workers can be assessed by means of MSF-similar to that of day-workers. Sleep times on free-days are, however, slightly influenced by the preceding shift (displacements <1 h), which are smallest after evening shifts. We therefore chose this shift-specific mid-sleep time (MSF(E)) to assess chronotype in shift-workers. The distribution of MSF(E) in our sample is identical to that of MSF in day-workers. We propose conversion algorithms for chronotyping shift-workers whose schedules do not include free days after evening shifts.

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