Paving the way for cross-site pooling of
Magnetoencephalography

Magnetoencephalography (MEG)

A noninvasive technique that detects magnetic fields above the surface of the head produced by postsynaptic potentials in the brain.
data

International Congress Series - 2007-06-01Weisend MP, Hanlon FM, Montano R, Ahlfors SP, Leuthold A, Pantazis D, Mosher JC, Georgopoulos AP, Hamalainen MS, Aine CJ10.1016/j.ics.2006.12.095
Pooling of
Magnetoencephalography

Magnetoencephalography (MEG)

A noninvasive technique that detects magnetic fields above the surface of the head produced by postsynaptic potentials in the brain.
data across laboratories is non-trivial because of differences in hardware, software, and environmental noise levels. To investigate these issues, we conducted a study with the same five subjects at three sites with different
MEG

Magnetoencephalography (MEG)

A noninvasive technique that detects magnetic fields above the surface of the head produced by postsynaptic potentials in the brain.
arrays: Elekta-Neuromag Vectorview (Boston), VSM MedTech Omega 275 (Albuquerque), and 4D Neuroimaging Magnes 3600 WH (Minneapolis). Subjects were run in a simple somatosensory paradigm. Phantom data were also taken at each site. We developed software to allow comparisons of test/retest reliability across subjects, machines, and analysis methods. Preliminary analyses showed excellent test/retest results within subjects across instruments. Analysis of phantom data showed a localization error of less than 2 mm across multiple software packages. Our results show that (1) instruments from different manufacturers yield similar results for somatosensory data, and that (2) multiple software packages produce very accurate results for simple source configurations.

Schizophrenia Classification using Working Memory
Magnetoencephalography

Magnetoencephalography (MEG)

A noninvasive technique that detects magnetic fields above the surface of the head produced by postsynaptic potentials in the brain.
ERD/ERS Patterns

2007 3rd International IEEE/EMBS Conference on Neural Engineering - 2007-05-02Ince NF, Stephane M, Tewfik AH, Pellizzer G, McClannahan K10.1109/CNE.2007.369708
In this paper we investigate the use of event related desynchronization (ERD) and synchronization (ERS) patterns extracted from magnetoencephalogram (
MEG

Magnetoencephalography (MEG)

A noninvasive technique that detects magnetic fields above the surface of the head produced by postsynaptic potentials in the brain.
) in a working memory task to discriminate between controls and patients with schizophrenia. In the experimental paradigm, sequential letters appearing on a screen are memorized by subjects. In one of two conditions the letters constituted a word. The ERD and ERS patterns are extracted in the theta, alpha, beta and gamma bands from 248 electrode locations covering the whole head. We noticed that most of the ERD patterns are localized on the left frontotemporal area in both word and nonword conditions in the late memorization stage. The beta band showed the most significant difference in this cortical area between controls and schizophrenia patients. By using a decision tree, 94.7% and 87.5% classification accuracy was obtained for controls and patients individually in both word and nonword conditions. Furthermore, we report that on...

The dynamic architecture of working memory in schizophrenia

BackgroundThe capacity to hold information in working memory is greater for the first and/or last items of a sequence of information (architecture), and varies according to the retention interval (dynamic) and the type of stimuli. Although working memory deficits in schizophrenia have been documented widely, it is not clear how its architecture and dynamics are affected by the disease.MethodsUsing two Sternberg paradigms - the recognition and the context-recall tasks - we investigated the effect of serial position, retention interval, type of stimuli, and task (type of encoding for the serial position) on working memory capacity in 26 schizophrenia patients and 20 healthy control subjects. A mixed model analysis of variance was applied to the proportion of correct responses and reaction time data.ResultsAll the experimental factors had significant effects. However, the most important effects were those of group, group x serial position, and group x delay interactions. The last two effects were...

Post-Traumatic Stress Disorder and Service Utilization in a Sample of Service Members from Iraq and Afghanistan

Military Medicine - 2007-04-01Erbes CR, Westermeyer JJ, Engdahl B, Johnson E10.7205/MILMED.172.4.359
Objective: The purpose of this study was to evaluate levels of post-traumatic stress disorder (
Posttraumatic Stress Disorder

Posttraumatic Stress Disorder (PTSD)

A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.
), depression, alcohol abuse, quality of life, and mental health service utilization among returnees from Operation Enduring Freedom and
Operation Iraqi Freedom

Operation Iraqi Freedom (OIF)

The period of the Iraq war lasting from 2003 to 2010 was referred to as Operation Iraqi Freedom (OIF) by the United States military. The conflict is also known as the War in Iraq, the Occupation of Iraq, the Second Gulf War, Gulf War II, and Gulf War 2.
. Methods: One hundred twenty returnees, enrolled for health care at a midwestern Veterans Affairs medical center, completed questionnaires approximately 6 months after their return from deployment. Results:
PTSD

Posttraumatic Stress Disorder (PTSD)

A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.
levels (12%) were consistent with previous research while problematic drinking levels were also elevated (33%).
PTSD

Posttraumatic Stress Disorder (PTSD)

A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.
and, to a lesser degree, alcohol abuse were associated with lower quality of life in multiple domains, even when controlling for the influence of depression. Of those screening positive for
PTSD

Posttraumatic Stress Disorder (PTSD)

A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.
, 56% reported using mental health services. Only 18% of those screening positive for alcohol abuse reported using such services. Conclusions:
PTSD

Posttraumatic Stress Disorder (PTSD)

A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.
and alcohol problems are prevalent in Operation Enduring Freedom/
OIF

Operation Iraqi Freedom (OIF)

The period of the Iraq war lasting from 2003 to 2010 was referred to as Operation Iraqi Freedom (OIF) by the United States military. The conflict is also known as the War in Iraq, the Occupation of Iraq, the Second Gulf War, Gulf War II, and Gulf War 2.
returnees and associated with lower quality of life....

Intelligence in action

Nature Neuroscience - 2007-02-01Chafee M, Ashe J10.1038/nn0207-142
The primate prefrontal cortex is associated with cognitive operations linked to intelligence. A study in Nature now shows that prefrontal neurons represent movement sequences at an abstract level, even when not required for the task.

A tribute to Tau

Glosing the Gap, The Scientific Writings of David N. Lee, Pepping, G-J and Grealy, M. A. - 2007-01-01Georgopoulos AP
I love r because it's a good-looking letter of the Greek alphabet. I also love r because it was invented by my good friend Dave N. Lee, long before we met. In fact, it was very nice of him to immortalize this measure, presciently, using Greek in 1976 (Lee, 1976), some 12-odd years before our acquaintance was made in 1984 in Beilefeld, Germany. At the time, we spent the whole night musing over tau with Claes Von Hofsten and Dave over a bottle of decent single malt. That night also clinched a lifelong friendship with Dave and Claes, and an ongoing collaboration with Dave for the past 15 years.

Large-Scale Organization of Preferred Directions in the Motor Cortex. II. Analysis of Local Distributions

The spatial arrangement of preferred directions (PDs) in the primary motor cortex has revealed evidence for columnar organization and short-range order. We investigated the large-scale properties of this arrangement. We recorded neural activity at sites on a grid covering a large region of the arm area of the motor cortex while monkeys performed a 3D reaching task. Sites were projected to the cortical surface along anatomically defined cortical columns and a PD was extracted from each site with directionally tuned activity. We analyzed the resulting 2D surface map of PDs. Consistent with previous studies, we found that any particular reaching direction was rerepresented at many points across the recorded area. In particular, we determined that the median radius of a cortical region required to represent the full complement of reaching directions is at most 1 mm. We also found that for the majority of regions of this size, the distribution of...

Large-Scale Organization of Preferred Directions in the Motor Cortex. I. Motor Cortical Hyperacuity for Forward Reaching

We used statistical methods for spherical density estimation to evaluate the distribution of preferred directions of motor cortical cells recorded from monkeys making reaching movements in 3D space. We found that this distribution, although broad enough to represent the entire 3D continuum of reaching directions, exhibited an enrichment for reaching forward from the body and, to a lesser degree, for reaching backward toward the body. The distribution of preferred directions of cells in the motor cortex may have important implications for motor cortical function and for the decoding of arm trajectories from population activity.

Computerized binary scale of auditory speech hallucinations (cbSASH)

Schizophrenia Research - 2006-12-01Stephane M, Pellizzer G, Roberts S, McClannahan K10.1016/j.schres.2006.05.020
BackgroundEvidence indicates that the neuropathology of auditory verbal hallucinations (AVH) varies according to their phenomenological characteristics. Therefore, AVH should be subgrouped accordingly in hallucinations research. As evaluation of these characteristics depends entirely on the patient report, obtaining measurement of the reliability of these reports is crucial.MethodA computerized binary scale of auditory speech hallucinations (cbSASH) was developed to evaluate the phenomenology of AVH. It includes two subscales (inconsistency and malingering) to assess the reliability of the patient report. The cbSASH was administered along with MMPI-2, a general psychopathology scale, which includes similar validity subscales. Thirty-four psychotic patients with history of AVH were enrolled in this study.ResultsThe scores on the inconsistency and malingering subscales of the cbSASH were correlated with the scores on the corresponding validity subscales in the MMPI-2. The combination of the malingering and inconsistency subscales provided robust measures of the reliability and ability of the patients' descriptions of their hallucinations.ConclusionThe...

Translational and developmental perspective on N-methyl-D-aspartate synaptic deficits in schizophrenia

Development and Psychopathology - 2006-09-01MacDonald III AW, Chafee M10.1017/S0954579406060421
Schizophrenia has long been approached from a translational perspective; however, new findings from the past decade have radically affected the dominant accounts of this illness. It is now possible to derive a consistent account of one contributing cause of schizophrenia across multiple levels of analysis, from genes to receptors, functional neuroanatomy, cognition, and symptoms. To this end, we summarize the data attributing the disorganization symptoms of schizophrenia to a failure of executive, prefrontal cortical processes. We describe the hypothesis that this failure reflects an impairment in N-methyl-D-aspartate (NMDA) glutamatergic neurotransmission, that is likely to involve both the dysregulated function of NMDA synapses, as well as the physical loss of NMDA synapses, particularly in prefrontal cortex. Dysregulation in NMDA synaptic function can be in turn attributed to polymorphisms in a variety of genes (regulator of G-protein signaling 4, dystrobrevin binding protein 1, neuregulin-1, d-amino acid oxidase activator, and others) that have been...

Time-dependent effects of discrete spatial cues on the planning of directed movements

Experimental Brain Research - 2006-06-01Pellizzer G, Hedges J, Villanueva RR10.1007/s00221-005-0317-2
The degree of preparation of a motor response varies with the information available regarding the response that will need to be executed and with the time provided to process that information. In experiment 1 we investigated the time-course of processing the information specified by discrete spatial cues regarding the upcoming target of directed movements. For this purpose we varied the number of cues that indicated the possible locations of the target and the duration of the cue period preceding the target. The results showed that the effects of processing the information provided by the cues developed progressively and stabilized after 0.2 s. In addition, the level of motor preparation reached was a function of number of cues. However, the effect of number of cues occurred even in the no cue period condition, i.e. when subjects could not have benefited from the information provided by the cues to prepare the response. Further...

Reply to Kurtzer and Herter

Our paper (Naselaris et al. 2006) examined statistically-in great detail-the distribution of a large number (>1,000) of preferred directions calculated from firing rates during free, unconstrained reaching movements in three-dimensional (3D) space. The enriched representation of forward (and to a lesser degree backward) reaching confers an obvious behavioral advantage and, very probably, is conferred on by the high frequency of occurrence of such movements in everyday life. A wealth of information from other studies, cited and discussed in our paper, supports this interpretation. All of this evidence notwithstanding, Kurtzer and Herter contend that a previous paper by Scott et al. (2001) offers the correct interpretation. ...

A comparative study of
Posttraumatic Stress Disorder

Posttraumatic Stress Disorder (PTSD)

A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.
assessment under standard conditions and in the field

International Journal of Methods in Psychiatric Research - 2006-05-19Erbes CR, Dikel TN, Eberly RE, Page WF, Engdahl B10.1002/mpr.185
Little is known about the performance of clinician-administered structured diagnostic interviews when given under variable levels of examiner training and monitoring. We sought to explore this question. We examined the performance of a self-report questionnaire and a structured clinical interview in the assessment of post-traumatic stress disorder (
PTSD

Posttraumatic Stress Disorder (PTSD)

A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.
) in two community samples of war veterans. One sample was interviewed under standard conditions (N = 372) and the other under unknown and less standardized conditions (N = 420), more closely approximating 'field conditions'. Interview results were used to predict questionnaire-based
PTSD

Posttraumatic Stress Disorder (PTSD)

A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.
status. Kappas, sensitivities, specificities, and positive predictive powers were moderate and of similar magnitude in both samples. Our results suggest that even under uncertain ('field') conditions, clinician-administered structured interviews can produce results comparable to those produced under more tightly controlled conditions.

Dipole analysis of magnetoencephalographic data during continuous shape copying

Experimental Brain Research - 2006-04-01Langheim F, Merkle AN, Leuthold A, Lewis S, Georgopoulos AP10.1007/s00221-005-0234-4
High density, whole head
MEG

Magnetoencephalography (MEG)

A noninvasive technique that detects magnetic fields above the surface of the head produced by postsynaptic potentials in the brain.
was used to study ten healthy human subjects (five females and five males) participating in a continuous shape-copying task. The task was performed with eyes open and fixated. The three-part task began with 45 s of fixation on a blue dot, after which the dot turned red, and a pentagon was presented around it. Subjects continued to fixate on the red dot for 45 s, after which it turned green. The green dot instructed subjects to begin copying the shape continuously for 45 s, without visual feedback, using a joystick mounted at arm's length. Data were collected at 1,017.25 Hz with a 248 sensor axial-gradiometer system. After cardiac artifact subtraction (Leuthold 2003), each corner was identified, and 1 s epochs (centered on each corner) were averaged and filtered from 1 to 44 Hz. Grand average flux maps demonstrated dipolar distributions identifying the most relevant sensors....

Synchronous dynamic brain networks revealed by magnetoencephalography

Proceedings of the National Academy of Sciences of the United States of America - 2006-01-10Langheim F, Leuthold A, Georgopoulos AP10.1073/pnas.0509623102
We visualized synchronous dynamic brain networks by using prewhitened (stationary) magnetoencephalography signals. Data were acquired from 248 axial gradiometers while 10 subjects fixated on a spot of light for 45 s. After fitting an autoregressive integrative moving average model and taking the residuals, all pairwise, zero-lag, partial cross-correlations (PPC0ij) between the i and j sensors were calculated, providing estimates of the strength and sign (positive and negative) of direct synchronous coupling between neuronal populations at a 1-ms temporal resolution. Overall, 51.4% of PCC0ij were positive, and 48.6% were negative. Positive PCC0ij occurred more frequently at shorter intersensor distances and were 72% stronger than negative ones, on the average. On the basis of the estimated PCC0ij, dynamic neural networks were constructed (one per subject) that showed distinct features, including several local interactions. These features were robust across subjects and could serve as a blueprint for evaluating dynamic brain function.

Neurophysiology of Perceptual and Motor Aspects of Interception

Journal of Neurophysiology - 2006-01-01Merchant H, Georgopoulos AP10.1152/jn.00422.2005
The interception of moving targets is a complex activity that involves a dynamic interplay of several perceptual and motor processes and therefore involves a rich interaction among several brain areas. Although the behavioral aspects of interception have been studied for the past three decades, it is only during the past decade that neural studies have been focused on this problem. In addition to the interception itself, several neural studies have explored, within that context, the underlying mechanisms concerning perceptual aspects of moving stimuli, such as optic flow and apparent motion. In this review, we discuss the wealth of knowledge that has accumulated on this topic with an emphasis on the results of neural studies in behaving monkeys.

Classification of adolescent psychotic disorders using linear discriminant analysis

Schizophrenia Research - 2006-01-01Pardo P, Georgopoulos AP, Kenny JT, Stuve TA, Findling RL, Schulz SC10.1016/j.schres.2006.05.007
BackgroundThe differential diagnosis between schizophrenia and bipolar disorder during adolescence presents a major clinical problem. Can these two diagnoses be differentiated objectively early in the courses of illness?MethodsWe used linear discrimination analysis (LDA) to classify 28 adolescent subjects into one of three diagnostic categories (healthy, N = 8; schizophrenia, N = 10; bipolar, N = 10) using subsets from a pool of 45 variables as potential predictors (22 neuropsychological test scores and 23 quantitative structural brain measurements). The predictor variables were adjusted for age, gender, race, and psychotropic medication. All possible subsets composed of k = 2-12 variables, from the set of 45 variables available, were evaluated using the robust leaving-one-subject-out method.ResultsThe highest correct classification (96%) of the 3 diagnostic categories was yielded by 9 sets of k = 12 predictors, comprising both neuropsychological and brain structural measures. Although each one of these sets misclassified one case, each set correctly classified...

Dynamics of Parietal Neural Activity during Spatial Cognitive Processing

Dynamic neural processing unrelated to changes in sensory input or motor output is likely to be a hallmark of cognitive operations. Here we show that neural representations of space in parietal cortex are dynamic while monkeys perform a spatial cognitive operation on a static visual stimulus. We recorded neural activity in area 7a during a visual maze task in which monkeys mentally followed a path without moving their eyes. We found that the direction of the followed path could be recovered from neuronal population activity. When the monkeys covertly processed a path that turned, the population representation of path direction shifted in the direction of the turn. This neural population dynamic took place during a period of unchanging visual input and showed characteristics of both serial and parallel processing. The data suggest that the dynamic evolution of parietal neuronal activity is associated with the progression of spatial cognitive operations.

On the relations between single cell activity in the motor cortex and the direction and magnitude of three-dimensional dynamic isometric force

Experimental Brain Research - 2005-11-01Boline J, Ashe J10.1007/s00221-005-0016-z
The role of the motor cortex in the control of both the direction and magnitude of dynamic force, when both are allowed to vary in 3D, is not known. We recorded the activity of 504 cells in the motor cortex of two monkeys during a behavioral task in which the subjects used a manipulandum to vary both the direction and magnitude of isometric force in 3D space. The majority (86%) of cells active in the task related to the direction, a tiny number (2.5%) to the magnitude, and a moderate number (11.5%) to both the direction and magnitude of dynamic force output. Finally, we compared neural activity in the same population of neurons during dynamic and static force output and found that the relations to direction and magnitude were very similar in both epochs. Our results indicate that during dynamic force production, cells in the motor cortex are primarily concerned with...

Magnetoencephalographic signals predict movement trajectory in space

Experimental Brain Research - 2005-11-01Georgopoulos AP, Langheim F, Leuthold A, Merkle AN10.1007/s00221-005-0028-8
Brain-machine interface (BMI) efforts have been focused on using either invasive implanted electrodes or training-extensive conscious manipulation of brain rhythms to control prosthetic devices. Here we demonstrate an excellent prediction of movement trajectory by real-time
MEG

Magnetoencephalography (MEG)

A noninvasive technique that detects magnetic fields above the surface of the head produced by postsynaptic potentials in the brain.
. Ten human subjects copied a pentagon for 45 s using an X-Y joystick while
MEG

Magnetoencephalography (MEG)

A noninvasive technique that detects magnetic fields above the surface of the head produced by postsynaptic potentials in the brain.
signals were being recorded from 248 sensors. A linear summation of weighted contributions of the
MEG

Magnetoencephalography (MEG)

A noninvasive technique that detects magnetic fields above the surface of the head produced by postsynaptic potentials in the brain.
signals yielded a predicted movement trajectory of high congruence to the actual trajectory (median correlation coefficient: r = 0.91 and 0.97 for unsmoothed and smoothed predictions, respectively). This congruence was robust since it remained high in cross-validation analyses (based on the first half of data to predict the second half; median correlation coefficient: r = 0.76 and 0.85 for unsmoothed and smoothed predictions, respectively).

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