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3. Multimodal neuroimaging of unconscious-covert-recognition
e100
Society Proceedings / Clinical Neurophysiology 119 (2008) e99–e164
3. Multimodal neuroimaging of unconscious-covert-recognition—M. Valde´s Sosa (Cuba)
logical bases of mental activity, as well as for the evaluation of brain development.
Models of information processing in Cognitive Neuropsychology (e.g. Visual recognition) have primarily originated from single-case studies (relying heavily on the discovery of double dissociations). Although the behavioral consequences of focal lesions would seem to provide the ultimate test of brain structural-functional relations, these cognitive models are very poor in neurophysiological and neuroanatomical detail. Conversely, integrated analysis of brain images derived from different modalities (e.g. Structural and functional magnetic resonance imaging, electrophysiological data, and tractography derived from diffusion tensor imaging), is leading to detailed proposals of the neural networks involved in the recognition of visual objects (including faces) in typical subjects. Conscious face recognition is conceived to sequentially involve early visual areas, the ”occipital face area (OFA)”, the ”fusiform face area (FFA)”, and anterior-inferior-temporal cortex. Based on combined fmri/tractography and source localization of the N170, we suggest that the face recognition network has a highly parallel architecture. Recently application of multimodal imaging to single cases with informative neuropsychological syndromes, including prosopagnosia (a selective impairment of face recognition), has permitting stronger tests of the models developed from neuro-imaging. Studies of prosopagnosia suggest separate networks underlying overt and covert (unconscious) face recognition, with several (possibly fast) routes connecting in parallel both OFA and FFA with orbitofrontal cortex enabling the latter process. These routes for unconscious face recognition could also operate in typical subjects.
doi:10.1016/j.clinph.2008.04.020
doi:10.1016/j.clinph.2008.04.019
4. Quantitative EEG: Its applications to neurology, psychophysiology and brain development—T. Harmony (Mexico)
5. Clinical applications of polysomnography (PSG) in epilepsy—H. Stokes, A.C. Stokes (Guatemala) 15 consecutive patients with epilepsy suspected of having nocturnal seizures were evaluated with an average of 8 h nocturnal polysomnography PSG. The parameters analyzed were: electrical cerebral activity EEG, oximetry electrooculogram, air flow, chest and abdominal movements, chin EMG, EKG, limb movements and snoring. No sedation was given to the patients and they were allowed to take their antiepileptic medications as usual the night of the examination. The types of seizure discharges were scored according to the sleep stages and the location of the discharges, also background activity and normal awake and sleeping. In patients with simple partial and generalized seizures most of of the discharges were found in phase II and phase I of sleep, the occurrence of discharges during REM sleep were very rare in contrast to previous reports that discharges corresponding to partial complex seizures are more common during REM sleep. Comorbidity between sleep obstructive apnea and epilepsy was not noticed in the patients studied. During the tests we disclosed cases of central sleep apnea presented in children with syncopal spells. PSG is an all night study that is very useful for studying epileptic phenomena that occurs mainly during sleep. In addition during sleep there are some normal phenomena that are paroxysmal such as sleep spindles, vertex waves and K complexes, in susceptible patients with either thalamic or cortical dysfunctions these normal phenomena could spark a paroxysmal discharge and explain why many seizures occurs predominantly during sleep. There are somes epileptic syndrome that occurs mainly during sleep and could be detected with PSG. doi:10.1016/j.clinph.2008.04.021
The aim for the present study was to analyze the application of different quantitative EEG procedures in the fields of neurology, psychophysiology and brain development. With that purpose we employed broad and narrow band spectral analyses, frequency domain brain electromagnetic tomography (FDVARETA, BET), time-frequency analysis and event-related synchronization. In patients with different type of brain lesions: tumors, infarcts, neurocysticercosis, Z brain maps referred to normative data of Absolute and Relative Power and FdVARETA analysis using Z BET images showed focal EEG abnormalities in 90% of the patients. The application of FdVARETA to the analysis of cognitive processes in different experimental conditions during the performance of mental tasks, showed that the origin of EEG frequencies that have been related to specific processes were located in brain structures directly related to the task. Time-frequency analyses of event-related oscillations demonstrated that there were simultaneous changes in different frequencies during the performance of the task. Differences between normal and abnormal brain development in babies were clearly shown by event-related synchronization. QEEG is a valuable tool for the study of brain damage when comparisons with a normative data base are made. It is also very useful for the study of the electrophysio-
6. Cuban human brain mapping project—P.A. Valde´s Sosa (Cuba) As a contribution to the International Human Brain Mapping Project, Cuba has initiated the construction of a comprehensive data base from a random sample of the population comprising medical, psychological and neuroimaging data. From a total sampling universe of 1939 more than 560 normal subjects have been recruited for the project, screened for normality and provided high density EEG recordings as well as T1, T2, PD, DWI images. Processing pipelines have been developed and applied for quantitative EEG tomography (qeegt), volumetric morphometry, cortical thickness (provided by the Montreal Neurological Institute) and DWI-based connectivity measures. Currently available are estimates of population values for these measures for ages 18–69 which are in agreement with previous results. New insights are provided by the analysis of relations between anatomical and physiological information, examples of which are correlations between DWI, reaction time and alpha peak frequency. The normative values established have already provided information about brain abnormalities in subjects with dyscalculia and mild
Society Proceedings / Clinical Neurophysiology 119 (2008) e99–e164
3. Multimodal neuroimaging of unconscious-covert-recognition—M. Valde´s Sosa (Cuba)
logical bases of mental activity, as well as for the evaluation of brain development.
Models of information processing in Cognitive Neuropsychology (e.g. Visual recognition) have primarily originated from single-case studies (relying heavily on the discovery of double dissociations). Although the behavioral consequences of focal lesions would seem to provide the ultimate test of brain structural-functional relations, these cognitive models are very poor in neurophysiological and neuroanatomical detail. Conversely, integrated analysis of brain images derived from different modalities (e.g. Structural and functional magnetic resonance imaging, electrophysiological data, and tractography derived from diffusion tensor imaging), is leading to detailed proposals of the neural networks involved in the recognition of visual objects (including faces) in typical subjects. Conscious face recognition is conceived to sequentially involve early visual areas, the ”occipital face area (OFA)”, the ”fusiform face area (FFA)”, and anterior-inferior-temporal cortex. Based on combined fmri/tractography and source localization of the N170, we suggest that the face recognition network has a highly parallel architecture. Recently application of multimodal imaging to single cases with informative neuropsychological syndromes, including prosopagnosia (a selective impairment of face recognition), has permitting stronger tests of the models developed from neuro-imaging. Studies of prosopagnosia suggest separate networks underlying overt and covert (unconscious) face recognition, with several (possibly fast) routes connecting in parallel both OFA and FFA with orbitofrontal cortex enabling the latter process. These routes for unconscious face recognition could also operate in typical subjects.
doi:10.1016/j.clinph.2008.04.020
doi:10.1016/j.clinph.2008.04.019
4. Quantitative EEG: Its applications to neurology, psychophysiology and brain development—T. Harmony (Mexico)
5. Clinical applications of polysomnography (PSG) in epilepsy—H. Stokes, A.C. Stokes (Guatemala) 15 consecutive patients with epilepsy suspected of having nocturnal seizures were evaluated with an average of 8 h nocturnal polysomnography PSG. The parameters analyzed were: electrical cerebral activity EEG, oximetry electrooculogram, air flow, chest and abdominal movements, chin EMG, EKG, limb movements and snoring. No sedation was given to the patients and they were allowed to take their antiepileptic medications as usual the night of the examination. The types of seizure discharges were scored according to the sleep stages and the location of the discharges, also background activity and normal awake and sleeping. In patients with simple partial and generalized seizures most of of the discharges were found in phase II and phase I of sleep, the occurrence of discharges during REM sleep were very rare in contrast to previous reports that discharges corresponding to partial complex seizures are more common during REM sleep. Comorbidity between sleep obstructive apnea and epilepsy was not noticed in the patients studied. During the tests we disclosed cases of central sleep apnea presented in children with syncopal spells. PSG is an all night study that is very useful for studying epileptic phenomena that occurs mainly during sleep. In addition during sleep there are some normal phenomena that are paroxysmal such as sleep spindles, vertex waves and K complexes, in susceptible patients with either thalamic or cortical dysfunctions these normal phenomena could spark a paroxysmal discharge and explain why many seizures occurs predominantly during sleep. There are somes epileptic syndrome that occurs mainly during sleep and could be detected with PSG. doi:10.1016/j.clinph.2008.04.021
The aim for the present study was to analyze the application of different quantitative EEG procedures in the fields of neurology, psychophysiology and brain development. With that purpose we employed broad and narrow band spectral analyses, frequency domain brain electromagnetic tomography (FDVARETA, BET), time-frequency analysis and event-related synchronization. In patients with different type of brain lesions: tumors, infarcts, neurocysticercosis, Z brain maps referred to normative data of Absolute and Relative Power and FdVARETA analysis using Z BET images showed focal EEG abnormalities in 90% of the patients. The application of FdVARETA to the analysis of cognitive processes in different experimental conditions during the performance of mental tasks, showed that the origin of EEG frequencies that have been related to specific processes were located in brain structures directly related to the task. Time-frequency analyses of event-related oscillations demonstrated that there were simultaneous changes in different frequencies during the performance of the task. Differences between normal and abnormal brain development in babies were clearly shown by event-related synchronization. QEEG is a valuable tool for the study of brain damage when comparisons with a normative data base are made. It is also very useful for the study of the electrophysio-
6. Cuban human brain mapping project—P.A. Valde´s Sosa (Cuba) As a contribution to the International Human Brain Mapping Project, Cuba has initiated the construction of a comprehensive data base from a random sample of the population comprising medical, psychological and neuroimaging data. From a total sampling universe of 1939 more than 560 normal subjects have been recruited for the project, screened for normality and provided high density EEG recordings as well as T1, T2, PD, DWI images. Processing pipelines have been developed and applied for quantitative EEG tomography (qeegt), volumetric morphometry, cortical thickness (provided by the Montreal Neurological Institute) and DWI-based connectivity measures. Currently available are estimates of population values for these measures for ages 18–69 which are in agreement with previous results. New insights are provided by the analysis of relations between anatomical and physiological information, examples of which are correlations between DWI, reaction time and alpha peak frequency. The normative values established have already provided information about brain abnormalities in subjects with dyscalculia and mild