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Publications

Publications by João Paulo Cunha

2008

Towards a Human-Robot Interface Based on the Electrical Activity of the Brain

Authors
Bento, VA; Cunha, JP; Silva, FM;

Publication
2008 8TH IEEE-RAS INTERNATIONAL CONFERENCE ON HUMANOID ROBOTS (HUMANOIDS 2008)

Abstract
Recent advances in computer hardware and signal processing assert that controlling certain functions by thoughts may represent a landmark in the way we interact with many output devices. This paper exploits the possibility of achieving a communication channel between the brain and a mobile robot through the modulation of the electroencephalogram (EEG) signal during motor imagery tasks. A major concern was directed towards designing a generalized and multi-purpose framework that supports rapid prototyping of various experimental strategies and operating modes. Preliminary results of brain-state estimation using EEG signals recorded during a self-paced left/right hand movement task are also presented. The user successfully learned to operate the system and how to better perform the motor-related tasks based on outcomes produced by its mental focus.

2011

Multivariate pattern analysis of brain structure: A diagnostic tool for Neurofibromatosis type 1

Authors
Duarte, J; Ribeiro, M; Violante, I; Cunha, G; Al Rawi, M; Cunha, JP; Castelo Branco, M;

Publication
1st Portuguese Meeting in Biomedical Engineering, ENBENG 2011

Abstract
Neurofibromatosis type 1 (NF1) is a genetic disorder characterized by increased predisposition for tumor development and cognitive deficits. In this work, we used maps of grey matter density obtained from Magnetic Resonance (MR) brain structural scans to distinguish between NF1 patients and healthy controls with a multivariate pattern analysis technique, Support Vector Machines. Up to 83% of all participants were correctly classified (mean sensitivity of 82%; mean specificity of 84%; significance level p< 0.01). This high level of classification accuracy of NF1 patients suggests this technique as a potential diagnostic tool. In addition, we determined the brain regions that the algorithm used to distinguish between NF1 patients and healthy controls. These regions were not identified as abnormal using univariate voxel-by-voxel comparison indicating that multivariate techniques are a useful powerful tool with which to identify potential structural defects in the NF1 brain. © 2011 IEEE.

1997

SIGIF: A digital signal interchange format with application in neurophysiology

Authors
Cunha, MB; Cunha, JPS; Silva, TOE;

Publication
IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING

Abstract
In this paper, the authors describe a biomedical digital-signal interchange format. The format supports both raw and processed data, multiple segments, several signal structures and representations, and an open architecture. Its versatility and adaptability allows the software to take advantage of any particular features of the acquisition hardware. The format has been used and improved in routine work during a five-year period involving the cooperation between two hospitals and one engineering research center. In order to support the format, an object oriented C language library has been developed and is also shortly described.

2005

What does an epileptiform spike look like in MEG? Comparison between coincident EEG and MEG spikes

Authors
Fernandes, JM; da Silva, AM; Huiskamp, G; Velis, DN; Manshanden, I; de Munck, JC; da Silva, FL; Cunha, JPS;

Publication
JOURNAL OF CLINICAL NEUROPHYSIOLOGY

Abstract
Recent investigations suggest that there are differences between the characteristics of EEG and MEG epileptiform spikes. The authors performed an objective characterization of the morphology of epileptiform spikes recorded simultaneously in both EEG and MEG to determine whether they present the same morphologic characteristics. Based on a stepwise approach, the authors performed a computer analysis of EEG and MEG of a set of coincident epileptiform transients selected by a senior clinical neurophysiologist in recordings of three patients with drug-resistant epilepsy. A computer-based algorithm was applied to extract parameters that could be used to describe quantitatively the morphology of the transients, followed by a statistical comparison over the extracted metrics of the EEG and MEG waveforms. EEG and MEG coincident events were statistically different with respect to several morphologic characteristics, such as duration, sharpness, and shape. The differences found appear to be a consequence of MEG signals not being influenced by volume propagation through the tissues with different conductivities that surround the brain, compared with EEG, and of the different orientation of the underlying dipolar sources. The results indicate that visual inspection of MEG spikes and automatic spike-detector algorithms should use criteria adapted to the specific characteristics of the MEG, and not simply those used on conventional EEG.

2011

Autonomic correlates of attachment insecurity in a sample of women with eating disorders

Authors
Dias, P; Soares, I; Klein, J; Cunha, JPS; Roisman, GI;

Publication
ATTACHMENT & HUMAN DEVELOPMENT

Abstract
This study examined associations between attachment insecurity and autonomic response during the Adult Attachment Interview (AAI) in a sample of 47 women with eating disorders using a new system for the synchronous acquisition of behavioral and physiological data: the Bio Dual-channel and Representation of Attachment Multimedia System (BioDReAMS; Soares, Cunha, Zhan Jian Li, Pinho, Neves, 1998). Consistent with the emerging literature on the psychophysiology of adult attachment, insecurity was positively correlated with electrodermal reactivity during the AAI. Furthermore, relatively secure patients showed some evidence of parasympathetic withdrawal, which can be conceptualized as evidence of more effective emotion regulation. Results suggest that, even among women with diagnosed psychopathology, security is associated with moreproductive patterns of psychophysiological response to attachment-related challenges.

2002

Interictal spike EEG source analysis in hypothalamic hamartoma epilepsy

Authors
Leal, AJR; Passao, V; Calado, E; Vieira, JP; Cunha, JPS;

Publication
CLINICAL NEUROPHYSIOLOGY

Abstract
Objective: The epilepsy associated with the hypothalamic hamartomas constitutes a syndrome with peculiar seizures, usually refractory to medical therapy, mild cognitive delay, behavioural problems and multifocal spike activity in the scalp electroencephalogram (EEG). The cortical origin of spikes has been widely assumed but not specifically demonstrated. Methods: We present results of a source analysis of interictal spikes from 4 patients (age 2-25 years) with epilepsy and hypothalamic hamartoma, using EEG scalp recordings (32 electrodes) and realistic boundary element models constructed from volumetric magnetic resonance imaging (MRIs). Multifocal spike activity was the most common finding, distributed mainly over the frontal and temporal lobes. A spike classification based on scalp topography was done and averaging within each class performed to improve the signal to noise ratio. Single moving dipole models were used, as well as the Rap-MUSIC algorithm. Results: All spikes with good signal to noise ratio were best explained by initial deep sources in the neighbourhood of the hamartoma, with late sources located in the cortex. Not a single patient could have his spike activity explained by a combination of cortical sources. Conclusions: Overall, the results demonstrate a consistent origin of spike activity in the subcortical region in the neighbourhood of the hamartoma, with late spread to cortical areas.

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