Effects of stimulus pulse rate on somatosensory adaptation in the human cortex

AbstractBackgroundIntracortical microstimulation (ICMS) of the somatosensory cortex can restore sensation to people with neurological diseases. However, many aspects of ICMS are poorly understood, including the effect of continuous stimulation on percept intensity over time.ObjectiveHere, we evaluate how tactile percepts, evoked by ICMS in the somatosensory cortex of a human participant adapt over time.MethodsWe delivered continuous and intermittent ICMS to the somatosensory cortex and assessed the reported intensity of tactile percepts over time in a human participant. Experiments were conducted across approximately one year and linear mixed effects models were used to assess significance.ResultsContinuous stimulation at high frequencies led to rapid decreases in intensity, while low frequency stimulation maintained percept intensity for longer periods. Burst-modulated stimulation extended the time before the intensity began to decrease, but all protocols ultimately resulted in complete sensation loss within one minute. Intermittent stimulation paradigms with several seconds between stimulus trains also led to decreases in intensity on many electrodes, but never resulted in extinction of sensation after over three minutes of stimulation. Additionally, longer breaks between each pulse train resulted in some recovery of the stimulus-evoked percepts. For several electrodes, intermittent stimulation had almost no effect on the perceived intensity.ConclusionsIntermittent ICMS paradigms were more effective at maintaining percepts, and given that transient activity in the somatosensory cortex dominates the response to object contact, this stimulation method may mimic natural cortical activity and improve the perception of stimulation over time.

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Neural stimulation and recording performance in human somatosensory cortex over 1500 days

10.1101/2020.01.21.20018341 ◽

2020 ◽

Cited By ~ 3

Author(s):

Christopher L. Hughes ◽

Sharlene N. Flesher ◽

Jeffrey M. Weiss ◽

John E. Downey ◽

Jennifer L. Collinger ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Somatosensory Cortex ◽

Microelectrode Arrays ◽

High Amplitude ◽

Detection Thresholds ◽

Cord Injury ◽

Human Participant ◽

Tactile Sensations ◽

Over Time

AbstractObjectiveIntracortical microstimulation (ICMS) in somatosensory cortex can restore sensation to people who have lost it due to spinal cord injury or other conditions. One potential challenge for chronic ICMS is whether neural recording and stimulation can remain stable over many years. This is particularly relevant since the recording quality of implanted microelectrode arrays frequently experience degradation over time and stimulation safety has been considered a potential barrier to the clinical use of ICMS. Our objective is to evaluate stability of recordings on intracortical stimulated and non-stimulated electrodes in a human participant across a long period of implantation. Additionally, we would like to assess the ability to evoke sensations with ICMS over time.ApproachIn a study investigating intracortical implants for a bidirectional brain-computer interface, we implanted microelectrode arrays with sputtered iridium oxide tips in the somatosensory cortex of a human participant with a cervical spinal cord injury. We regularly stimulated through electrodes on these microelectrode arrays to evoke tactile sensations on the hand. Here, we quantify the stability of these electrodes in comparison to non-stimulated electrodes implanted in motor cortex over 1500 days in two ways: recorded signal quality and electrode impedances. Additionally, we quantify the perceptual stability of ICMS-evoked sensations with detection thresholds.Main resultsWe found that recording quality, as assessed by the number of electrodes with high-amplitude waveform recordings (> 100 µV), peak-to-peak voltage, noise, and signal-to-noise ratio, generally decreased over time on stimulated and non-stimulated electrodes. However, stimulated electrodes were much more likely to continue to record high-amplitude signals than non-stimulated electrodes. Interestingly, the detection thresholds for stimulus-evoked tactile sensations decreased over time from a median of 31.5 μA at Day 100 to 10.4 μA at Day 1500, with the most substantial changes occurring between Day 100 and Day 500.SignificanceThese results provide evidence that ICMS in human somatosensory cortex can be provided over long periods of time without deleterious effects on recording or stimulation capabilities. In fact, psychophysical sensitivity to stimulation improves over time and stimulation itself may promote more robust long-term neural recordings.

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Trends in mortality, co-morbidity and treatment after acute myocardial infarction in patients with rheumatoid arthritis 1998–2013

European Heart Journal Acute Cardiovascular Care ◽

10.1177/2048872619896069 ◽

2020 ◽

Vol 9 (8) ◽

pp. 931-938 ◽

Cited By ~ 1

Author(s):

Mattias Skielta ◽

Lars Söderström ◽

Solbritt Rantapää-Dahlqvist ◽

Solveig W Jonsson ◽

Thomas Mooe

Keyword(s):

Rheumatoid Arthritis ◽

Myocardial Infarction ◽

Heart Failure ◽

Atrial Fibrillation ◽

Acute Myocardial Infarction ◽

Congestive Heart Failure ◽

Cox Regression Analysis ◽

Co Morbidity ◽

One Year ◽

Over Time

Aims: Rheumatoid arthritis may influence the outcome after an acute myocardial infarction. We aimed to compare trends in one-year mortality, co-morbidities and treatments after a first acute myocardial infarction in patients with rheumatoid arthritis versus non-rheumatoid arthritis patients during 1998–2013. Furthermore, we wanted to identify characteristics associated with mortality. Methods and results: Data for 245,377 patients with a first acute myocardial infarction were drawn from the Swedish Register of Information and Knowledge about Swedish Heart Intensive Care Admissions for 1998–2013. In total, 4268 patients were diagnosed with rheumatoid arthritis. Kaplan-Meier analysis was used to study mortality trends over time and multivariable Cox regression analysis was used to identify variables associated with mortality. The one-year mortality in rheumatoid arthritis patients was initially lower compared to non-rheumatoid arthritis patients (14.7% versus 19.7%) but thereafter increased above that in non-rheumatoid arthritis patients (17.1% versus 13.5%). In rheumatoid arthritis patients the mean age at admission and the prevalence of atrial fibrillation increased over time. Congestive heart failure decreased more in non-rheumatoid arthritis than in rheumatoid arthritis patients. Congestive heart failure, atrial fibrillation, kidney failure, rheumatoid arthritis, prior diabetes mellitus and hypertension were associated with significantly higher one-year mortality during the study period 1998–2013. Conclusions: The decrease in one-year mortality after acute myocardial infarction in non-rheumatoid arthritis patients was not applicable to rheumatoid arthritis patients. This could partly be explained by an increased age at acute myocardial infarction onset and unfavourable trends with increased atrial fibrillation and congestive heart failure in rheumatoid arthritis. Rheumatoid arthritis per se was associated with a significantly worse prognosis.

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Incidence, Characteristics, and Prognosis of Incidentally Discovered Hepatocellular Carcinoma after Liver Transplantation

Journal of Transplantation ◽

10.1155/2016/1916387 ◽

2016 ◽

Vol 2016 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Walid El Moghazy ◽

Samy Kashkoush ◽

Glenda Meeberg ◽

Norman Kneteman

Keyword(s):

Hepatocellular Carcinoma ◽

Liver Transplantation ◽

Tumor Recurrence ◽

Patient Survival ◽

Steady Increase ◽

Liver Transplants ◽

Significant Difference ◽

One Year ◽

Over Time

Background. We aimed to assess incidentally discovered hepatocellular carcinoma (iHCC) over time and to compare outcome to preoperatively diagnosed hepatocellular carcinoma (pdHCC) and nontumor liver transplants.Methods.We studied adults transplanted with a follow-up of at least one year. Patients were divided into 3 groups according to diagnosis of hepatocellular carcinoma.Results.Between 1990 and 2010, 887 adults were transplanted. Among them, 121 patients (13.6%) had pdHCC and 32 patients (3.6%) had iHCC; frequency of iHCC decreased markedly over years, in parallel with significant increase in pdHCC. Between 1990 and 1995, 120 patients had liver transplants, 4 (3.3%) of them had iHCC, and only 3 (2.5%) had pdHCC, while in the last 5 years, 263 patients were transplanted, 7 (0.03%) of them had iHCC, and 66 (25.1%) had pdHCC (P<0.001). There was no significant difference between groups regarding patient survival; 5-year survival was 74%, 75.5%, and 77.3% in iHCC, pdHCC, and non-HCC groups, respectively (P=0.702). Patients with iHCC had no recurrences after transplant, while pdHCC patients experienced 17 recurrences (15.3%) (P=0.016).Conclusions.iHCC has significantly decreased despite steady increase in number of transplants for hepatocellular carcinoma. Patients with iHCC had excellent outcomes with no tumor recurrence and survival comparable to pdHCC.

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Changes in commitment to change among leaders in home help services

Leadership in Health Services ◽

10.1108/lhs-04-2014-0038 ◽

2015 ◽

Vol 28 (3) ◽

pp. 216-227 ◽

Cited By ~ 1

Author(s):

Kristina Westerberg ◽

Susanne Tafvelin

Keyword(s):

Organizational Change ◽

Structured Interviews ◽

Change Initiatives ◽

Commitment To Change ◽

Content Type ◽

Team Meetings ◽

Home Help ◽

Home Help Services ◽

One Year ◽

Over Time

Purpose – The purpose of the this study was to explore the development of commitment to change among leaders in the home help services during organizational change and to study this development in relation to workload and stress. During organizational change initiatives, commitment to change among leaders is important to ensure the implementation of the change. However, little is known of development of commitment of change over time. Design/methodology/approach – The study used a qualitative design with semi-structured interviews with ten leaders by the time an organizational change initiative was launched and follow-up one year later. Thematic content analysis was used to analyze the interviews. Findings – Commitment to change is not static, but seems to develop over time and during organizational change. At the first interview, leaders had a varied pattern reflecting different dimensions of commitment to change. One year later, the differences between leaders’ commitment to change was less obvious. Differences in commitment to change had no apparent relationship with workload or stress. Research limitations/implications – The data were collected from one organization, and the number of participants were small which could affect the results on workload and stress in relation to commitment to change. Practical implications – It is important to support leaders during organizational change initiatives to maintain their commitment. One way to accomplish this is to use management team meetings to monitor how leaders perceive their situation. Originality/value – Qualitative, longitudinal and leader studies on commitment to change are all unusual, and taken together, this study shows new aspects of commitment.

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A longitudinal study on emotional distress among local government staff seven years after the 2008 Wenchuan earthquake in China

BMC Public Health ◽

10.1186/s12889-021-10726-8 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Yunge Fan ◽

Lili Guan ◽

Hu Xiang ◽

Xianmei Yang ◽

Guoping Huang ◽

...

Keyword(s):

Longitudinal Study ◽

Local Government ◽

Wenchuan Earthquake ◽

Emotional Distress ◽

Early Stage ◽

2008 Wenchuan Earthquake ◽

The 2008 Wenchuan Earthquake ◽

One Year ◽

Self Reporting Questionnaire ◽

Over Time

Abstract Background The current study examined the change in local government staff’s emotional distress over 7 years after the 2008 Wenchuan earthquake, and the influence of earthquake exposure and professional quality of life (ProQOL) on emotional distress. Methods This longitudinal study assessed 250 participants at 1 year after the earthquake; 162 (64.8%) were followed up at 7 years. Emotional distress was assessed with the Self-Reporting Questionnaire (SRQ) at both time points. We assessed ProQOL, including compassion satisfaction, burnout, and secondary traumatic stress, and earthquake exposure at 1 year. Wilcoxon signed-rank tests were performed to test longitudinal changes in emotional distress. Hierarchical multiple regression was conducted to examine the effect of earthquake exposure and ProQOL. Results The positive screening rate of emotional distress (SRQ ≥ 8) was 37.6 and 15.4% at one and 7 years, respectively. Emotional distress scores declined over time (p < 0.001). Earthquake exposure and ProQOL predicted one-year (ps < 0.05) but not seven-year emotional distress, whereas burnout predicted both one-year (p = 0.018) and seven-year (p = 0.047) emotional distress. Conclusions Although emotional distress can recover over time, it persists even 7 years later. Actions to reduce burnout during the early stage of post-disaster rescue have long-term benefits to staff’s psychological outcomes.

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Abstract 3143: Reverse Hemodynamic Remodelling May Be Possible Over Time

Circulation ◽

10.1161/circ.116.suppl_16.ii_705-b ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Lynne W Stevenson ◽

Yong K Cho ◽

J. T Heywood ◽

Robert C Bourge ◽

William T Abraham ◽

...

Keyword(s):

Heart Failure ◽

Chronic Heart Failure ◽

Pulmonary Artery ◽

Right Ventricular ◽

Nyha Class ◽

Systolic Pressure ◽

Filling Pressure ◽

Class Iii ◽

One Year ◽

Over Time

Introduction : Elevated filling pressures are a hallmark of chronic heart failure. They can be reduced acutely during HF hospitalization but the hemodynamic impact of ongoing therapy to maintain optivolemia has not been established. Methods and Results : After recent HF hospitalization, 274 NYHA Class III or IV HF patients were enrolled in the COMPASS-HF study at 28 experienced HF centers and received intense HF management (average 24.7 staff contacts/ 6 months) ± access to filling pressure information to adjust diuretics to maintain optivolemia, usually defined as estimated pulmonary artery diastolic (PAD) pressure of 12±4 mmHg. Filling pressure information was available for half the patients during the first 6 months (the Chronicle group, <Access), and for all patients during the next 6 months. Diuretics were adjusted 12.7 times per patient in the Chronicle group and 8.2 times per patient in the Control (-Access) group during the first 6 months (p = 0.0001). Compared to baseline, decreases in RV systolic pressure (RVSP) and ePAD were significant for the +Access patients by one year (p=0.0012 and p =.04, respectively). The Control patients exhibited a similar trend 6 months after crossing to +Access (figure ). Conclusions: Targeted therapeutic adjustments, based on continuous filling pressures along with intensification of HF management contacts, are associated with a reduction in chronic left-sided filling pressures and right ventricular load.

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POSTFUNDOPLICATION DYSPHAGIA CAUSES SIMILAR WATER INGESTION DYNAMICS AS ACHALASIA

Arquivos de Gastroenterologia ◽

10.1590/s0004-28032016000200009 ◽

2016 ◽

Vol 53 (2) ◽

pp. 98-102 ◽

Cited By ~ 1

Author(s):

Roberto Oliveira DANTAS ◽

Carla Manfredi SANTOS ◽

Rachel Aguiar CASSIANI ◽

Leda Maria Tavares ALVES ◽

Weslania Viviane NASCIMENTO

Keyword(s):

Surgical Treatment ◽

Gastroesophageal Reflux Disease ◽

Gastroesophageal Reflux ◽

Chagas Disease ◽

Water Volume ◽

Flow Volume ◽

Water Ingestion ◽

Idiopathic Achalasia ◽

One Year ◽

Over Time

ABSTRACT Background - After surgical treatment of gastroesophageal reflux disease dysphagia is a symptom in the majority of patients, with decrease in intensity over time. However, some patients may have persistent dysphagia. Objective - The objective of this investigation was to evaluate the dynamics of water ingestion in patients with postfundoplication dysphagia compared with patients with dysphagia caused by achalasia, idiopathic or consequent to Chagas' disease, and controls. Methods - Thirty-three patients with postfundoplication dysphagia, assessed more than one year after surgery, together with 50 patients with Chagas' disease, 27 patients with idiopathic achalasia and 88 controls were all evaluated by the water swallow test. They drunk, in triplicate, 50 mL of water without breaks while being precisely timed and the number of swallows counted. Also measured was: (a) inter-swallows interval - the time to complete the task, divided by the number of swallows during the task; (b) swallowing flow - volume drunk divided by the time taken; (c) volume of each swallow - volume drunk divided by the number of swallows. Results - Patients with postfundoplication dysphagia, Chagas' disease and idiopathic achalasia took longer to ingest all the volume, had an increased number of swallows, an increase in interval between swallows, a decrease in swallowing flow and a decrease in water volume of each swallow compared with the controls. There was no difference between the three groups of patients. There was no correlation between postfundoplication time and the results. Conclusion - It was concluded that patients with postfundoplication dysphagia have similar water ingestion dynamics as patients with achalasia.

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Fast Tracks and Inner Journeys: Crafting Portable Selves for Contemporary Careers

Administrative Science Quarterly ◽

10.1177/0001839217720930 ◽

2017 ◽

Vol 63 (3) ◽

pp. 479-525 ◽

Cited By ~ 24

Author(s):

Gianpiero Petriglieri ◽

Jennifer Louise Petriglieri ◽

Jack Denfeld Wood

Keyword(s):

Process Model ◽

Cultural Influence ◽

Business Administration ◽

The Self ◽

The Other ◽

Self In Relation ◽

Working Lives ◽

One Year ◽

Mobile Working ◽

Over Time

Through a longitudinal, qualitative study of 55 managers engaged in mobile careers across organizations, industries, and countries, and pursuing a one-year international master’s of business administration (MBA), we build a process model of the crafting of portable selves in temporary identity workspaces. Our findings reveal that contemporary careers in general, and temporary membership in an institution, fuel people’s efforts to craft portable selves: selves endowed with definitions, motives, and abilities that can be deployed across roles and organizations over time. Two pathways for crafting a portable self—one adaptive, the other exploratory—emerged from the interaction of individuals’ aims and concerns with institutional resources and demands. Each pathway involved developing a coherent understanding of the self in relation to others and to the institution that anchored participants to their current organization while preparing them for future ones. The study shows how institutions that host members temporarily can help them craft selves that afford a sense of agentic direction and enduring connection, tempering anxieties and bolstering hopes associated with mobile working lives. It also suggests that institutions serving as identity workspaces for portable selves may remain attractive and extend their cultural influence in an age of workforce mobility.

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Effect of Phasic Activation on Endplate Potential in Rat Diaphragm

Journal of Neurophysiology ◽

10.1152/jn.1999.82.6.3030 ◽

1999 ◽

Vol 82 (6) ◽

pp. 3030-3040 ◽

Cited By ~ 15

Author(s):

Michelle Moyer ◽

Erik van Lunteren

Keyword(s):

Time Course ◽

Complete Recovery ◽

Stimulation Frequency ◽

Drop Out ◽

Rat Diaphragm ◽

Continuous Stimulation ◽

Intermittent Stimulation ◽

Rate Of Decline ◽

Phasic Activation

Neuromuscular junction endplate potentials (EPPs) decrease quickly and to a large extent during continuous stimulation. The present study examined the hypothesis that EPP rundown recovers rapidly, thereby substantially preserving neurotransmission during intermittent compared with continuous stimulation. Studies were performed in vitro on rat diaphragm, using μ-conotoxin to allow recording of normal-sized EPPs from intact fibers. During continuous 5- to 100-Hz stimulation, EPP amplitude declined with a biphasic time course. The initial fast rate of decline was modulated substantially by stimulation frequency, whereas the subsequent slow rate of decline was relatively frequency independent. During intermittent 5- to 100-Hz stimulation (duty cycle 0.33), EPP amplitude declined rapidly during each train, but recovered substantially by the onset of the following train. The intra-train declines were substantially greater than the inter-train declines in EPP amplitude. Intra-train reductions in EPP amplitude were stimulation frequency dependent, based on both the total decline and rate constant of EPP decline. In contrast, the degree of recovery from train to train was independent of stimulation frequency, indicating low frequency dependence of inter-train rundown. The substantial recovery of EPP amplitude in between trains resulted in greater cumulative EPP size during intermittent compared with continuous stimulation. During continuous stimulation, EPP drop-out was only seen during 100-Hz stimulation; this was completed mitigated during intermittent stimulation. Miniature EPP size was unaffected by either continuous or intermittent stimulation. The pattern of rapid intra-train rundown and slow inter-train rundown of EPP size during intermittent stimulation is therefore due to rapid changes in the magnitude of neurotransmitter release rather than to axonal block or postsynaptic receptor desensitization. These findings indicate considerable rundown of EPP amplitudes within a stimulus train, with near complete recovery by the onset of the next train. This substantially attenuates the decrement in EPP amplitude during intermittent compared with continuous stimulation, thereby preserving the integrity of neurotransmission during phasic activation.

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Neglecting Decline: Remembered and Predicted Personal Development Diverge from Actual Longitudinal Change.

10.31234/osf.io/43qvh ◽

2019 ◽

Author(s):

Sarah Molouki ◽

Daniel Bartels ◽

Oleg Urminsky

Keyword(s):

Longitudinal Study ◽

Personal Development ◽

Absolute Magnitude ◽

Longitudinal Change ◽

Personal Change ◽

Future Change ◽

Change Over Time ◽

Time Period ◽

One Year ◽

Over Time

A one-year longitudinal study was conducted to investigate the accuracy of people’s assessmentsof their own personal change over time. We compared people’s predicted, actual, and recalledchange in their personality, values, and preferences over this time period. On average,participants underestimated the absolute magnitude of their personal change, yet simultaneouslyoverestimated their net improvement, in both prediction and recall. This effect was due to anasymmetry whereby people selectively neglected negative changes, especially prospectively.Although participants in our sample both improved and declined over the year, they were morelikely to remember past improvements than declines, and made nearly uniformly positivepredictions of future change. We discuss how the current findings reconcile researchdemonstrating expectations of personal improvement (e.g., Wilson & Ross, 2001; Kanten &Teigen, 2008) with other research that suggests people overpredict their personal stability(Quoidbach, Gilbert, & Wilson, 2013).

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