Control freaks: Towards optimal selection of control conditions for fMRI neurofeedback studies

Publication date: Available online 10 November 2018

Source: NeuroImage

Author(s): Bettina Sorger, Frank Scharnowski, David E.J. Linden, Michelle Hampson, Kymberly D. Young

Abstract

fMRI Neurofeedback research employs many different control conditions. Currently, there is no consensus as to which control condition is best, and the answer depends on what aspects of the neurofeedback-training design one is trying to control for. These aspects can range from determining whether participants can learn to control brain activity via neurofeedback to determining whether there are clinically significant effects of the neurofeedback intervention. Lack of consensus over criteria for control conditions has hampered the design and interpretation of studies employing neurofeedback protocols. This paper presents an overview of the most commonly employed control conditions currently used in neurofeedback studies and discusses their advantages and disadvantages. Control conditions covered include no control, treatment-as-usual, bidirectional-regulation control, feedback of an alternative brain signal, sham feedback, and mental-rehearsal control. We conclude that the selection of the control condition(s) should be determined by the specific research goal of the study and best procedures that effectively control for relevant confounding factors.

from Imaging via a.sfakia on Inoreader https://ift.tt/2FpmybE

Modeling of dynamic cerebrovascular reactivity to spontaneous and externally induced CO2 fluctuations in the human brain using BOLD-fMRI

Publication date: Available online 10 November 2018

Source: NeuroImage

Author(s): Prokopis C. Prokopiou, Kyle T.S. Pattinson, Richard G. Wise, Georgios D. Mitsis

Abstract

In this work, we investigate the regional characteristics of the dynamic interactions between arterial CO₂ and BOLD (dynamic cerebrovascular reactivity - dCVR) during normal breathing and hypercapnic, externally induced step CO₂ challenges. To obtain dCVR curves at each voxel, we use a custom set of basis functions based on the Laguerre and gamma basis sets. This allows us to obtain robust dCVR estimates both in larger regions of interest (ROIs), as well as in individual voxels. We also implement classification schemes to identify brain regions with similar dCVR characteristics. Our results reveal considerable variability of dCVR across different brain regions, as well as during different experimental conditions (normal breathing and hypercapnic challenges), suggesting a differential response of cerebral vasculature to spontaneous CO₂ fluctuations and larger, externally induced CO₂ changes that are possibly associated with the underlying differences in mean arterial CO₂ levels. The clustering results suggest that anatomically distinct brain regions are characterized by different dCVR curves that in some cases do not exhibit the standard, positive valued curves that have been previously reported. They also reveal a consistent set of dCVR cluster shapes for resting and forcing conditions, which exhibit different distribution patterns across brain voxels.

from Imaging via a.sfakia on Inoreader https://ift.tt/2qErCOX

Human or not human? Performance monitoring ERPs during human agent and machine supervision

Publication date: Available online 10 November 2018

Source: NeuroImage

Author(s): Bertille Somon, Aurélie Campagne, Arnaud Delorme, Bruno Berberian

Abstract

Performance monitoring is a critical process which allows us to both learn from our own errors, and also interact with other human beings. However, our increasingly automated world requires us to interact more and more with automated systems, especially in risky environments. The present EEG study aimed at investigating and comparing the neuro-functional correlates associated with performance monitoring of an automated system and a human agent using a vertically-oriented arrowhead version of the flanker task. Given the influence of task difficulty on performance monitoring, two levels of difficulty were considered in order to assess their impact on supervision activity. A large N2P3 complex in fronto-central regions was observed for both human agent error detection and system error detection during supervision. Using a cluster-based permutation analysis, a significantly decreased P3-like component was found for system compared to human agent error detection. This variation is in line with various psychosocial behavioral studies showing a difference between human-human and human-machine interactions, even though it was not clearly anticipated. Finally, the activity observed during error detection was significantly reduced in the difficult condition compared to the easy one, for both system and human agent supervision. Overall, this study is a first step towards the characterization of the neurophysiological correlates underlying system supervision, and a better understanding of their evolution in more complex environments. To go further, these results need to be replicated in other experiments with various paradigms to assess the robustness of the pattern and decrease during system supervision.

from Imaging via a.sfakia on Inoreader https://ift.tt/2FpD5fk

Prognostic significance of bone morphogenetic protein 6 (BMP6) expression, clinical and pathological factors in clinically node-negative oral squamous cell carcinoma (OSCC)

Publication date: Available online 10 November 2018

Source: Journal of Cranio-Maxillofacial Surgery

Author(s): Petar Suton, Ante Bolanca, Lovorka Grgurevic, Igor Erjavec, Iva Nikles, Danko Muller, Spomenka Manojlovic, Slobodan Vukicevic, Mladen Petrovecki, Stjepan Dokuzovic, Ivica Luksic

Summary

Bone morphogenetic protein 6 (BMP6) has unique properties regarding structure and function in supporting bone formation during development and adult life. Despite its known role in various malignant tumors, the prognostic significance of BMP6 expression in oral squamous cell carcinoma (OSCC) remains unknown. The aim of the study was to investigate immunohistochemical expression of BMP6 in OSCC in correlation with clinical and pathological parameters, disease recurrence and survival. In addition, we investigated other parameters in order to identify prognosticators of neck metastases and final outcome. The study included 120 patients with clinically T1-3N0 OSCC who were primarily surgically treated between 2003 and 2008. There were 99 (82.5%) male and 21 (17.5%) female patients. The five-year disease-specific survival for the whole cohort was 79.7%. Tumors smaller than 2 cm in diameter showed higher incidence of strong BMP6 expression. No statistical correlation was observed between other clinico-pathological factors and BMP6 expression. Expression of BMP6 was not associated with disease recurrence and survival. BMP6 may not serve as prognosticator of final outcome or recurrence in clinically node-negative OSCC subjects. In multivariate analysis predictors of poorer survival were positive surgical margin, moderate tumor cell differentiation and pathological involvement of levels IV and/or V.

from OroFacial via a.sfakia on Inoreader https://ift.tt/2T06tvL

The feasibility of rib grafts in long span mandibular defects reconstruction: a long term follow up

Publication date: Available online 10 November 2018

Source: Journal of Cranio-Maxillofacial Surgery

Author(s): Ahmed M.A. Habib, Shady A. Hassan

Abstract

Aims

To evaluate the efficiency of reconstruction of long span mandibular defects using split rib bundle bone graft.

Materials and methods

Six hundred patients with long span mandibular defects (more than 6 cm long), following resection of aggressive mandibular tumours, were reconstructed with split rib bundle bone graft technique. Immediate reconstruction was performed in all patients. A reconstruction plate was used to support the graft. Two ribs were harvested from the right side of the chest, split into four halves and used to restore the continuity of the mandible. The inclusion criterion was post-surgical mandibular bony defects without soft tissue deficiency. Defects with a history of previous or need of future irradiation were excluded.

Results

The appearance of the patients was accepted in 550 patients. Functional reconstruction was done in 320 patients by osseointegrated dental implants (after 15 months), and removable prosthesis in 150 patients. Infection was minor in 31 patients, moderate in 47 patients and severe in 42 patients. Partial loss of graft, up to 25%, due to moderate infection was reported. Total or near total loss of graft due to severe infection was corrected by reoperation six months later.

Conclusions

This technique is simple, safe, and can be effectively used to reconstruct long-span mandibular defects with minimal complications in selected patients.

from OroFacial via a.sfakia on Inoreader https://ift.tt/2zMCyxZ

Recovery Pattern following Bimaxillary Orthognathic Surgery: Differences between Sexes

Publication date: Available online 10 November 2018

Source: Journal of Cranio-Maxillofacial Surgery

Author(s): In-Seok Song, Jimi Choi, Un-Bong Baik, Jae-Jun Ryu, Jong-Woo Lim, Young-Jun Choi, Ui-Lyong Lee

Abstract

The investigators hypothesized there would be differences between the sexes in recovery pattern following bimaxillary orthognathic surgery as measured by patient responses at 5 weeks postprocedure. A total of 378 participants underwent bimaxillary orthognathic surgery with or without adjunctive procedures. Participants received questionnaires 5 weeks postsurgery when they visited the outpatient clinic. The questionnaires include variances in surgical factors by sex, and postoperative symptoms which were most difficult to tolerate experiences by sex, respectively. Females were more likely to undergo malarplasty (zygoma reduction) than were male participants (P = <.001), and they required larger maxillary setback than did male participants (P = .003). Malarplasty was significantly correlated with ear fullness in total and female participants (p-value .018, .016, respectively). Snoring is significantly associated with malarplasty and segment osteotomy procedure without gender predominance (p-value= .026, .028, respectively). Over half of participants complained of nasal congestion (55.6%), followed by swelling (29.3%), pain (15.4%), breathing difficulty (10.6%). In conclusion, males and females showed different patterns of postoperative recovery following bimaxillary orthognathic surgery.

from OroFacial via a.sfakia on Inoreader https://ift.tt/2T4JMXa

A simple method to estimate the linear length of the orbital floor in complex orbital surgery

Publication date: Available online 9 November 2018

Source: Journal of Cranio-Maxillofacial Surgery

Author(s): Konstantinos Natsis, Maria Piagkou, Ioannis Chryssanthou, Georgios P. Skandalakis, Georgios Tsakotos, Giannoulis Piagkos, Constantinus Politis

Abstract

Background

The orbital floor (OrF) and infraorbital rim (IOR) repair in cases of complete destruction is challenging mainly due to the fact that the defect length cannot be measured. The aim of the current study is to develop a method of calculating the Orf length by using the gender and the lengths of the medial, superior and lateral orbital walls (OrW) of the same orbit.

Material and methods

Ninety-seven (59 male and 38 female) European adult dry skulls were classified according to age: 20-39, 40-59 and 60 years and above. The length of each OrW was measured by using the direct distance between the optic foramen and a landmark in each orbital rim.

Results

A side asymmetry was detected for the lengths of the inferior, superior and medial OrW. Although a gender dimorphism was detected, no correlation with the age was found. Using the Stepwise multiple regression analysis two formulas were developed, one for the right and one for the left OrF with coefficient of determination R² 0.43 and 0.57, respectively.

Conclusions

The proposed formulas represent a simple, applicable and individualized method to calculate the OrF linear length in cases of complete destruction of the IOR and OrF, with accuracy and without the use of expertise material. Such data may improve the surgery planning of orbital floor fractures and complex orbital reconstructions.

from OroFacial via a.sfakia on Inoreader https://ift.tt/2zIOdho