- Email: [email protected]
26. Using software for change in science
Society Proceedings / Clinical Neurophysiology 119 (2008) e99–e164
alternating pattern; (5) the abnormalities of sleep microstructure; (6) the abnormalities of EEG spectral activities; (7) the relations between EEG and non EEG variables; (8) the presence of abnormal phenomena either in the EEG or in the non-EEG variables. Taking as examples insomnia, fibromyalgia, periodic limb movements, sleep apnea and sleepwalking these abnormalities are presented and analysed in order to achieve physiopathological information. Sleep fragmentation is a feature of poor sleep. It can be induced by periodic limb movements of even by sleep apnea. Furthermore other parameters and symptoms may induce awakenings such as arrhythmias, oesophageal reflux, nicturia, pain, headaches, nocturnal eating and excessive dreaming. Their corresponding relations to the sleep structure are detailed. doi:10.1016/j.clinph.2008.04.038
23. EEG–fMRI: (Germany)
Neurovascular
coupling—K. Uludag
The relationship between hemodynamic response and underlying neural activity is still poorly understood. Complementary non-invasive multimodality experiments on human subjects such as EEG and fMRI can provide new insights into this link. In this study, using very short visual stimulus durations (0.1–5 ms) we have investigated the relationship between fMRI and visual evoked potentials (VEP). Short stimulus durations rather than commonly used standard durations in fMRI experiments are ideal to investigate the neuro-vascular coupling because non-linearities of hemodynamic response are minimized. We found that both the integral of the BOLD response and the peak value of N75 response increase monotonically with increasing stimulus duration. Other VEP peaks (e.g. P100) did not correlate with the BOLD signal. However, to alteration in stimulus duration, both measurements respond non-linearly though differently. Thus, the non-linearities in N75 component of VEP response cannot alone account for the non-linearities observed in BOLD response. In addition, we will present results of how EEG oscillations (power and phase) are altered by very short stimulations. This study suggests that, although under some experimental conditions correlations exist between fMRI and electrophysiology signals, both are not causally linked to each other. doi:10.1016/j.clinph.2008.04.039
e105
anatomical information can be introduced into the problem of characterizing brain functional circuits involved in the cognitive and sensorial processing using the electric/magnetic activity from EEG/MEG and fMRI. The new method to characterize the intravoxel anisotropy provides information about the probability of finding a fiber in a particular spatial orientation; and maps of the probability to find a particular number of fibers and the most probable number of fibers for each voxel. On other hand the fiber tracking methodology is developed under Graph theory formalism, where different anatomical connectivity matrices were defined: Anatomical Connection Strength (ACS), Anatomical Connection Density (ACD) and Anatomical Connection Probability (ACP). Based on this approach, complex networks properties such as small-world attributes, efficiency, degree distribution, are studied in subjects of the Cuban Human Brain Mapping Project. doi:10.1016/j.clinph.2008.04.040
25. Simultaneous EEG and fMRI– A unique neurophysiologic technique—J. Stern (USA) The simultaneous recording of EEG and functional MRI (SEM) is unique in its direct integration of two central brain mapping techniques. As such, SEM promises equally unique insights into cerebral activity, but it also presents significant challenges. Combining two techniques is not a novel concept. Indeed, all brain mapping techniques are expected to provide incomplete information about brain function and a more full understanding arises from comparisons of different techniques’ results. However, SEM is unique by producing images that include aspects of EEG’s high temporal resolution and sensitivity to electrophysiologic changes and functional MRI’s high spatial resolution and sensitivity to metabolic changes. Combining these differing aspects of brain function poses a challenge to interpretation because the result conveys something different than both EEG and functional MRI. Acquisition of data with SEM is another challenge. Safely recording EEG from individuals in the MRI environment and then removing the electrical noise from the EEG data is not straightforward, but several successful solutions are now in place. Despite these challenges, SEM continues to develop in its applicability to multiple areas of clinical neurophysiology, including epilepsy, sleep, and cognitive neuroscience. doi:10.1016/j.clinph.2008.04.041
24. Methods to determine anatomical and functional connectivity—L. Melie Garcı´a, Y. Iturria Medina, E. Canales Rodrı´guez, Y. Alema´n Go´mez, P.A. Valde´s Herna´ndez (Cuba)
26. Using software for change in science—M. Brett (United Kingdom)
Diffusion Weighted Imaging is a noninvasive technique that provides quantitative maps of the micro structural organization and physiological features of living tissues. There are three levels of analysis of this neuroimaging modality: (1) characterization of the intravoxel anisotropy, (2) fiber tracking that estimates routes linking two particular structures in the brain, (3) anatomic measures definition to characterize the anatomical networks in the brain. The aim of this work is twofold: (1) to develop new methods in the three levels above mentioned and (2) to discuss how this
It used to be said that the world runs on oil, but now it is at least as true to say that the world runs on software. This is nowhere more true than the world of neuroimaging. The most successful neuroimaging software is open-source, for good reason. To understand the data, you need to understand the software, and, as methods change fast, understanding data means being able to read and use code. This is one major reason why SPM has been so successful in fMRI analysis. The move towards open-source has brought with it a new spirit of openness and
e106
Society Proceedings / Clinical Neurophysiology 119 (2008) e99–e164
equality. Open-source developers have a famous bias towards working with people from many countries and backgrounds, because influence in software development is based on ability and productivity. Developers of open-source code are much more able to share their ideas with other researchers, and are more likely to have their ideas applied and discussed. The movement to open-source is a movement towards greater openness and equality in science, and has the potential to strengthen the community of scientists in many countries.
troublesome symptoms including pain. A number of new therapeutic agents have been developed in this regard, with varying degrees of efficacy. Symptomatic management also involves the appropriate use of rehabilitative resources including aids and appliances to maximize activities of daily living and general quality of life. doi:10.1016/j.clinph.2008.04.044
doi:10.1016/j.clinph.2008.04.042
29. Neurophysiological evaluation of neuropathic pain: From receptors to perception—J. Valls Sole´ (Spain)
27. Combined and synchronized acquisition of EEG/fMRI— I. Gutberlet (Germany)
Neuropathic pain is arising as a direct consequence of a lesion or disease affecting the somatosensory system. Psychophysical and neurophysiological tests are important for the assessment of lesion characteristics and the different pathophysiological mechanisms involved in central and peripheral neuropathic pain. Microneurography is appropriate to investigate receptor and axonal transduction levels. Conventional nerve conduction studies, long latency responses and evoked potentials of large and small fibers help in the assessment of nerve conduction block or functional axonal loss. Psychophysical tests (quantitative sensory testing), assessment of conscious awareness of the stimulus and evaluation of the effects of sensory stimuli on autonomic function are useful in the assessment of the effects of the central nervous system mechanisms involved in pain sensation. Neuropathy causing pain is related to axonal loss in pain fibers together with ectopic discharges in damaged axons. Loss of descending inhibitory control of pain inputs manifests with reduced habituation of responses of the autonomic nervous system to repeated pain stimuli. Neurophysiological and psychophysical techniques are useful in the assessment of peripheral and central neuropathic pain. Neuropathic pain manifests as dysfunctions of pain pathways at various levels.
The concurrent derivation of EEG and fMRI has become immensely popular over the last decade since it provides insights into brain function that can neither be achieved with EEG or fMRI alone. Early studies used interleaved recordings with EEG and fMRI acquisitions being done during distinct phases, but modern EEG/fMRI measurements use continuous fMRI recordings without any determinable periods of no MR acquisition. There has been a constant increase in the magnetic field strength used and the concomitant increases in gradient strength and speed, as well as the desire to run the gradients at full power even during combined acquisitions require special hardware and software efforts to obtain EEG of the quality required and desired. Another major problem in combined recordings is the minute phase jitter between the MR and EEG system acquisition clocks, which has a profound influence on the resulting EEG data quality obtainable. However, this effect can be strongly reduced and often even completely abolished by software or hardware based synchronization of the two clock signals. This talk will focus on the different methods of ’ex post facto’ and ’a priori’ synchronization of combined EEG/fMRI recordings and will highlight the data quality achievable with each method in contrast to their respective feasibility. Technical and methodological promises, current problems and theoretical limits will be highlighted. doi:10.1016/j.clinph.2008.04.043
28. Symptomatic treatment of acquired peripheral neuropathies—O. Hardiman (Ireland) The pathogenesis of peripheral neuropathy is heterogeneous. Management is focussed at two levels- to identify the pathogenic mechanism and reverse it if possible; and to treat the symptomatic manifestations of the condition. While the pathogenesis of up to 50% of neuropathies remains idiopathic, symptomatic treatment strategies can enhance quality of life. In the case of some neuropathies, including those that are immune mediated, disease modifying treatment can also ameliorate the cardinal symptom of weakness–although the precise treatment regime requires individual tailoring for optimal response.The first line treatment of most immune mediated neuropathies is either I.V. Ig or plasma exchange. Symptomatic management of other non-inflammatory neuropathies is centered on the pharmacological treatment of
doi:10.1016/j.clinph.2008.04.045
30. Role of Hoffman (H) reflex study in proximal nerve lesions in upper extremities—S. Sharma (Canada) Routine nerve conduction techniques are not able to detect proximal lesions in root compressions, plexopahies and inflammatory neuropathies. F wave latencies often demonstrate the only and earliest abnormality in GBS. Tibial HR can be instrumental in the diagnosis of S1 root lesion. H reflex is recordable in children under the age of 3 years from all extremity muscles. In adult upper extremities, HR is recordable from Flexor Carpi Radialis muscle (FCR-H), representing the C7 spinal segment. It is less successfully recorded using surface electrodes in comparison with Tibial HR. The objectives of the following two separate studies were to (1). Correlate the presence of Brachioradialis H reflex (BR-H) in obstetric brachial plexopathies (OBP) with clinical recovery. (2). Standardize the technique of recording the FCR-H for clinical use in adult population. BR-H representing C5-6 spinal segments were recorded in 106 obps that commonly involve the upper trunk of Brachial Plexus. In the absence of BR-H, there was 8.4 times more chance of little or no clinical improvement than the group in which it was present. The sensitivity of the absence of BR-H
alternating pattern; (5) the abnormalities of sleep microstructure; (6) the abnormalities of EEG spectral activities; (7) the relations between EEG and non EEG variables; (8) the presence of abnormal phenomena either in the EEG or in the non-EEG variables. Taking as examples insomnia, fibromyalgia, periodic limb movements, sleep apnea and sleepwalking these abnormalities are presented and analysed in order to achieve physiopathological information. Sleep fragmentation is a feature of poor sleep. It can be induced by periodic limb movements of even by sleep apnea. Furthermore other parameters and symptoms may induce awakenings such as arrhythmias, oesophageal reflux, nicturia, pain, headaches, nocturnal eating and excessive dreaming. Their corresponding relations to the sleep structure are detailed. doi:10.1016/j.clinph.2008.04.038
23. EEG–fMRI: (Germany)
Neurovascular
coupling—K. Uludag
The relationship between hemodynamic response and underlying neural activity is still poorly understood. Complementary non-invasive multimodality experiments on human subjects such as EEG and fMRI can provide new insights into this link. In this study, using very short visual stimulus durations (0.1–5 ms) we have investigated the relationship between fMRI and visual evoked potentials (VEP). Short stimulus durations rather than commonly used standard durations in fMRI experiments are ideal to investigate the neuro-vascular coupling because non-linearities of hemodynamic response are minimized. We found that both the integral of the BOLD response and the peak value of N75 response increase monotonically with increasing stimulus duration. Other VEP peaks (e.g. P100) did not correlate with the BOLD signal. However, to alteration in stimulus duration, both measurements respond non-linearly though differently. Thus, the non-linearities in N75 component of VEP response cannot alone account for the non-linearities observed in BOLD response. In addition, we will present results of how EEG oscillations (power and phase) are altered by very short stimulations. This study suggests that, although under some experimental conditions correlations exist between fMRI and electrophysiology signals, both are not causally linked to each other. doi:10.1016/j.clinph.2008.04.039
e105
anatomical information can be introduced into the problem of characterizing brain functional circuits involved in the cognitive and sensorial processing using the electric/magnetic activity from EEG/MEG and fMRI. The new method to characterize the intravoxel anisotropy provides information about the probability of finding a fiber in a particular spatial orientation; and maps of the probability to find a particular number of fibers and the most probable number of fibers for each voxel. On other hand the fiber tracking methodology is developed under Graph theory formalism, where different anatomical connectivity matrices were defined: Anatomical Connection Strength (ACS), Anatomical Connection Density (ACD) and Anatomical Connection Probability (ACP). Based on this approach, complex networks properties such as small-world attributes, efficiency, degree distribution, are studied in subjects of the Cuban Human Brain Mapping Project. doi:10.1016/j.clinph.2008.04.040
25. Simultaneous EEG and fMRI– A unique neurophysiologic technique—J. Stern (USA) The simultaneous recording of EEG and functional MRI (SEM) is unique in its direct integration of two central brain mapping techniques. As such, SEM promises equally unique insights into cerebral activity, but it also presents significant challenges. Combining two techniques is not a novel concept. Indeed, all brain mapping techniques are expected to provide incomplete information about brain function and a more full understanding arises from comparisons of different techniques’ results. However, SEM is unique by producing images that include aspects of EEG’s high temporal resolution and sensitivity to electrophysiologic changes and functional MRI’s high spatial resolution and sensitivity to metabolic changes. Combining these differing aspects of brain function poses a challenge to interpretation because the result conveys something different than both EEG and functional MRI. Acquisition of data with SEM is another challenge. Safely recording EEG from individuals in the MRI environment and then removing the electrical noise from the EEG data is not straightforward, but several successful solutions are now in place. Despite these challenges, SEM continues to develop in its applicability to multiple areas of clinical neurophysiology, including epilepsy, sleep, and cognitive neuroscience. doi:10.1016/j.clinph.2008.04.041
24. Methods to determine anatomical and functional connectivity—L. Melie Garcı´a, Y. Iturria Medina, E. Canales Rodrı´guez, Y. Alema´n Go´mez, P.A. Valde´s Herna´ndez (Cuba)
26. Using software for change in science—M. Brett (United Kingdom)
Diffusion Weighted Imaging is a noninvasive technique that provides quantitative maps of the micro structural organization and physiological features of living tissues. There are three levels of analysis of this neuroimaging modality: (1) characterization of the intravoxel anisotropy, (2) fiber tracking that estimates routes linking two particular structures in the brain, (3) anatomic measures definition to characterize the anatomical networks in the brain. The aim of this work is twofold: (1) to develop new methods in the three levels above mentioned and (2) to discuss how this
It used to be said that the world runs on oil, but now it is at least as true to say that the world runs on software. This is nowhere more true than the world of neuroimaging. The most successful neuroimaging software is open-source, for good reason. To understand the data, you need to understand the software, and, as methods change fast, understanding data means being able to read and use code. This is one major reason why SPM has been so successful in fMRI analysis. The move towards open-source has brought with it a new spirit of openness and
e106
Society Proceedings / Clinical Neurophysiology 119 (2008) e99–e164
equality. Open-source developers have a famous bias towards working with people from many countries and backgrounds, because influence in software development is based on ability and productivity. Developers of open-source code are much more able to share their ideas with other researchers, and are more likely to have their ideas applied and discussed. The movement to open-source is a movement towards greater openness and equality in science, and has the potential to strengthen the community of scientists in many countries.
troublesome symptoms including pain. A number of new therapeutic agents have been developed in this regard, with varying degrees of efficacy. Symptomatic management also involves the appropriate use of rehabilitative resources including aids and appliances to maximize activities of daily living and general quality of life. doi:10.1016/j.clinph.2008.04.044
doi:10.1016/j.clinph.2008.04.042
29. Neurophysiological evaluation of neuropathic pain: From receptors to perception—J. Valls Sole´ (Spain)
27. Combined and synchronized acquisition of EEG/fMRI— I. Gutberlet (Germany)
Neuropathic pain is arising as a direct consequence of a lesion or disease affecting the somatosensory system. Psychophysical and neurophysiological tests are important for the assessment of lesion characteristics and the different pathophysiological mechanisms involved in central and peripheral neuropathic pain. Microneurography is appropriate to investigate receptor and axonal transduction levels. Conventional nerve conduction studies, long latency responses and evoked potentials of large and small fibers help in the assessment of nerve conduction block or functional axonal loss. Psychophysical tests (quantitative sensory testing), assessment of conscious awareness of the stimulus and evaluation of the effects of sensory stimuli on autonomic function are useful in the assessment of the effects of the central nervous system mechanisms involved in pain sensation. Neuropathy causing pain is related to axonal loss in pain fibers together with ectopic discharges in damaged axons. Loss of descending inhibitory control of pain inputs manifests with reduced habituation of responses of the autonomic nervous system to repeated pain stimuli. Neurophysiological and psychophysical techniques are useful in the assessment of peripheral and central neuropathic pain. Neuropathic pain manifests as dysfunctions of pain pathways at various levels.
The concurrent derivation of EEG and fMRI has become immensely popular over the last decade since it provides insights into brain function that can neither be achieved with EEG or fMRI alone. Early studies used interleaved recordings with EEG and fMRI acquisitions being done during distinct phases, but modern EEG/fMRI measurements use continuous fMRI recordings without any determinable periods of no MR acquisition. There has been a constant increase in the magnetic field strength used and the concomitant increases in gradient strength and speed, as well as the desire to run the gradients at full power even during combined acquisitions require special hardware and software efforts to obtain EEG of the quality required and desired. Another major problem in combined recordings is the minute phase jitter between the MR and EEG system acquisition clocks, which has a profound influence on the resulting EEG data quality obtainable. However, this effect can be strongly reduced and often even completely abolished by software or hardware based synchronization of the two clock signals. This talk will focus on the different methods of ’ex post facto’ and ’a priori’ synchronization of combined EEG/fMRI recordings and will highlight the data quality achievable with each method in contrast to their respective feasibility. Technical and methodological promises, current problems and theoretical limits will be highlighted. doi:10.1016/j.clinph.2008.04.043
28. Symptomatic treatment of acquired peripheral neuropathies—O. Hardiman (Ireland) The pathogenesis of peripheral neuropathy is heterogeneous. Management is focussed at two levels- to identify the pathogenic mechanism and reverse it if possible; and to treat the symptomatic manifestations of the condition. While the pathogenesis of up to 50% of neuropathies remains idiopathic, symptomatic treatment strategies can enhance quality of life. In the case of some neuropathies, including those that are immune mediated, disease modifying treatment can also ameliorate the cardinal symptom of weakness–although the precise treatment regime requires individual tailoring for optimal response.The first line treatment of most immune mediated neuropathies is either I.V. Ig or plasma exchange. Symptomatic management of other non-inflammatory neuropathies is centered on the pharmacological treatment of
doi:10.1016/j.clinph.2008.04.045
30. Role of Hoffman (H) reflex study in proximal nerve lesions in upper extremities—S. Sharma (Canada) Routine nerve conduction techniques are not able to detect proximal lesions in root compressions, plexopahies and inflammatory neuropathies. F wave latencies often demonstrate the only and earliest abnormality in GBS. Tibial HR can be instrumental in the diagnosis of S1 root lesion. H reflex is recordable in children under the age of 3 years from all extremity muscles. In adult upper extremities, HR is recordable from Flexor Carpi Radialis muscle (FCR-H), representing the C7 spinal segment. It is less successfully recorded using surface electrodes in comparison with Tibial HR. The objectives of the following two separate studies were to (1). Correlate the presence of Brachioradialis H reflex (BR-H) in obstetric brachial plexopathies (OBP) with clinical recovery. (2). Standardize the technique of recording the FCR-H for clinical use in adult population. BR-H representing C5-6 spinal segments were recorded in 106 obps that commonly involve the upper trunk of Brachial Plexus. In the absence of BR-H, there was 8.4 times more chance of little or no clinical improvement than the group in which it was present. The sensitivity of the absence of BR-H