Broca's region and adjacent cortex presumably take part in workin... more Broca's region and adjacent cortex presumably take part in working memory (WM) processes. Electrophysiologically, these processes are reflected in synchronized oscillations. We present the first study exploring the effects of a stroke causing Broca's aphasia on these processes and specifically on synchronized functional WM networks. We used high-density EEG and coherence analysis to map WM networks in ten Broca's patients and ten healthy controls during verbal WM task. Our results demonstrate that a stroke resulting in Broca's aphasia also alters two distinct WM networks. These theta and gamma functional networks likely reflect the executive and the phonological processes, respectively. The striking imbalance between task-related theta synchronization and desynchronization in Broca's patients might represent a disrupted balance between task-positive and WM-irrelevant functional networks. There is complete disintegration of left fronto-centroparietal gamma network in Broca's patients, which could reflect the damaged phonological loop.
... Blaž Koritnik1, Miha Kočevar2, Jernej Knific3, Rok Tavčar4 and Lilijana Šprah5 1University Me... more ... Blaž Koritnik1, Miha Kočevar2, Jernej Knific3, Rok Tavčar4 and Lilijana Šprah5 1University Medical Center Ljubljana, Neurological Clinic, Institute for Clinical ... Nihče od udeležencev ni imel predhodne izkušnje s testom n nazaj in ni vnaprej vedel, kakšen je namen poskusa. ...
2008 IEEE International Conference on Robotics and Biomimetics, 2009
In this paper an upgrade of a Phantom Premium 1.5 haptic device which enables haptic manipulation... more In this paper an upgrade of a Phantom Premium 1.5 haptic device which enables haptic manipulation within a magnetic resonance imaging (MRI) environment is presented. A mechanical extension has been developed that allows Phantom to operate at a safe distance, away from a high-density magnetic field of an fMRI scanner. A study presented in this paper has confirmed electromagnetic compatibility
Izvleček Izhodišča: Motnje v delovanju možganov so velika skupina nevroloških in psihiatričnih bo... more Izvleček Izhodišča: Motnje v delovanju možganov so velika skupina nevroloških in psihiatričnih bolezni. Skupaj pomenijo največji javnozdravstveni problem v Evropi in zahodnem svetu, saj predstavljajo tretjino vsega bolezenskega bremena družbe. Pojavljajo se pogosto in povzročajo tako akutne kot kronične okvare zdravja in upad v vsakdanjem delovanju bolnikov. O prvi raziskavi Evropskega sveta za možgane (angl. European Brain Council, EBC) o pomenu možganskih bolezni iz leta 2005 so v Zdravniškem vestniku že poročali, tokrat pa predstavljamo rezultate nove razširjene raziskave EBC iz leta 2010. Raziskava je zajela 19 večjih skupin možganskih bolezni v 30 evropskih državah s skupaj 514 milijoni prebivalcev (EU27 ter Islandija, Norveška in Švica). Z uporabo enakega metodološkega pristopa posamezne države sedaj predstavljajo njihove ocene tovrstnih stroškov. Prispevek podaja ocene stroškov motenj v delovanju možganov za Slovenijo v 2010.
Expression of acetylcholine receptors (AChRs) in the extrajunctional muscle regions, but not in t... more Expression of acetylcholine receptors (AChRs) in the extrajunctional muscle regions, but not in the neuromuscular junctions, is repressed by propagated electric activity in muscle fibers. During regeneration, subsynaptic-like specializations accumulating AChRs are induced in new myotubes by agrin attached to the synaptic basal lamina at the places of former motor endplates even in the absence of innervation. We examined whether AChRs still accumulated at these places when the regenerating muscles were ectopically innervated and the former synaptic places became extrajunctional. Rat soleus muscles were injured by bupivacaine and ischemia to produce complete myofiber degeneration. The soleus muscle nerve was permanently severed and the muscle was ectopically innervated by the peroneal nerve a few millimeters away from the former junctional region. After 4 weeks of regeneration, the muscles contracted upon nerve stimulation, showed little atrophy and the cross-section areas of their fibers were completely above the range in non-innervated regenerating muscles, indicating successful innervation. Subsynaptic-like specializations in the former junctional region still accumulated AChRs (and acetylcholinesterase) although no motor nerve endings were observed in their vicinity and the cross-section area of their fibers clearly demonstrated that they were ectopically innervated. We conclude that the expression of AChRs at the places of the former neuromuscular junctions in the ectopically innervated regenerated soleus muscles is activity-independent.
... Cerebral Cortex 12(8):877-882 9. Jensen O and Lisman JE (2005) Hippocampal sequence-encoding ... more ... Cerebral Cortex 12(8):877-882 9. Jensen O and Lisman JE (2005) Hippocampal sequence-encoding driven by a cortical multi-item working ... Vito Logar University of Ljubljana, Faculty of electrical engineering Trzaska 25, SI-1000 Ljubljana, Slovenia [email protected]
Whilst the act of sniffing can provide us with an indirect method to study the central mechanisms... more Whilst the act of sniffing can provide us with an indirect method to study the central mechanisms of respiratory control, functional neuroimaging now provides us with a tool to directly visualise the activity of the human brain during this voluntary action using functional magnetic resonance imaging (fMRI).
A 42-year-old man was evaluated for snoring and sleep apnea. Overnight polysomnography revealed 2... more A 42-year-old man was evaluated for snoring and sleep apnea. Overnight polysomnography revealed 28 events per hour on the apnea-hypopnea index. To determine the site of obstruction and determine treatment, dynamic MRI with concurrent EEG monitoring in natural sleep was performed. We recorded 2 mechanisms of total occlusion: at the oropharyngeal level and due to movement of the uvula during snoring (videos 1 and 2). 1 Two different mechanisms suggested against surgical therapy; he was treated with a continuous positive airway pressure mask at 7 cm H 2 O, with a good outcome.
Numerous reports have shown that performing working-memory tasks causes an elevated rhythmic coup... more Numerous reports have shown that performing working-memory tasks causes an elevated rhythmic coupling in different areas of the brain; it has been suggested that this indicates information exchange. Since the information exchanged is encoded in brain waves and measurable by electroencephalography (EEG) it is reasonable to assume that it can be extracted with an appropriate method. In our study we made an attempt to extract the information using an artificial neural network (ANN), which can be considered as a stimulus-response model with a state observer. The EEG was recorded from three subjects while they performed a modified Sternberg task that required them to respond to each task with the answer ''true'' or ''false''. The study revealed that a stimulus-response model can successfully be identified by observing phase-demodulated theta-band EEG signals 1 s prior to a subject's answer. The results also showed that it was possible to predict the answers from the EEG signals with an average reliability of 75% for all the subjects. From this we concluded that it is possible to observe the system states and thus predict the correct answer using the EEG signals as inputs.
gyri (BA 32,31), the inferior and middle frontal gyri (BA 6,9,10), the superior temporal sulcus a... more gyri (BA 32,31), the inferior and middle frontal gyri (BA 6,9,10), the superior temporal sulcus and the subcortical grey matter (caudate and thalamus). The critical cortical activations were found in the right-sided intraparietal sulcus (IPS), anterior cingulate cortex (ACC), and right-sided lateral prefrontal cortex (PFC). These three regions were entered into the DCM. Comparison on group level revealed superiority of dynamic causal models in which IPS and alternatively PFC served as input regions as compared to a model in which ACC is assumed to receive external inputs. No significant difference was observed between fully connected models with IPS (model 1) and PFC (model 2) as input regions. Subsequent analysis of intrinsic connectivity within two investigated models (1,2) disclosed significant parallel forward connections from IPS to the frontal areas (model 1) and from PFC to ACC and IPS (model 2).
using both systems. Examination with system B demonstrated larger area of echogenic SN than measu... more using both systems. Examination with system B demonstrated larger area of echogenic SN than measurements with system A (mean area ± SE: 15.4 ± 1.4 mm 2 vs.12.4 ± 1.2 mm 2 ; p = 0.00). Enlargement of echogenic SN area ( 3 20 mm 2 ) was found in 5 and 8 subjects using system A and B, respectively. SN size measured by system A and B ) correlated significantly (Spearman coefficient: 0.72; p = 0.00).
Background: The subject of brain-computer interfaces (BCIs) represents a vast and still mainly un... more Background: The subject of brain-computer interfaces (BCIs) represents a vast and still mainly undiscovered land, but perhaps the most interesting part of BCIs is trying to understand the information exchange and coding in the brain itself. According to some recent reports, the phase characteristics of the signals play an important role in the information transfer and coding. The mechanism of phase shifts, regarding the information processing, is also known as the phase coding of information. Objective: The authors would like to show that electroencephalographic (EEG) signals, measured during the performance of different gripping-force control tasks, carry enough information for the successful prediction of the gripping force, as applied by the subjects, when using a methodology based on the phase demodulation of EEG data. Since the presented methodology is non-invasive it could be used as an alternative approach for the development of BCIs. Materials and methods: In order to predict the gripping force from the EEG signals we used a methodology that uses subsequent signal processing methods: simplistic filtering methods, for extracting the appropriate brain rhythm; principal component analysis, for achieving the linear independence and detecting the source of the signal; and the phase-demodulation method, for extracting the phase-coded information about the gripping force. A fuzzy inference system is then used to predict the gripping force from the processed EEG data.
PHASE CODING OF INFORMATION IN THE HUMAN BRAIN Vito LOGARa , Igor KRJANCa , Ale BELIČa , Simon ... more PHASE CODING OF INFORMATION IN THE HUMAN BRAIN Vito LOGARa , Igor KRJANCa , Ale BELIČa , Simon BREANb ,Bla KORITNIKb , Janez ZIDARb a Faculty of Electrical Engineering, University of Ljubljana, Traka 25, SI-1000 Ljubljana ... [8] O. Jensen and CD ...
Broca's region and adjacent cortex presumably take part in workin... more Broca's region and adjacent cortex presumably take part in working memory (WM) processes. Electrophysiologically, these processes are reflected in synchronized oscillations. We present the first study exploring the effects of a stroke causing Broca's aphasia on these processes and specifically on synchronized functional WM networks. We used high-density EEG and coherence analysis to map WM networks in ten Broca's patients and ten healthy controls during verbal WM task. Our results demonstrate that a stroke resulting in Broca's aphasia also alters two distinct WM networks. These theta and gamma functional networks likely reflect the executive and the phonological processes, respectively. The striking imbalance between task-related theta synchronization and desynchronization in Broca's patients might represent a disrupted balance between task-positive and WM-irrelevant functional networks. There is complete disintegration of left fronto-centroparietal gamma network in Broca's patients, which could reflect the damaged phonological loop.
... Blaž Koritnik1, Miha Kočevar2, Jernej Knific3, Rok Tavčar4 and Lilijana Šprah5 1University Me... more ... Blaž Koritnik1, Miha Kočevar2, Jernej Knific3, Rok Tavčar4 and Lilijana Šprah5 1University Medical Center Ljubljana, Neurological Clinic, Institute for Clinical ... Nihče od udeležencev ni imel predhodne izkušnje s testom n nazaj in ni vnaprej vedel, kakšen je namen poskusa. ...
2008 IEEE International Conference on Robotics and Biomimetics, 2009
In this paper an upgrade of a Phantom Premium 1.5 haptic device which enables haptic manipulation... more In this paper an upgrade of a Phantom Premium 1.5 haptic device which enables haptic manipulation within a magnetic resonance imaging (MRI) environment is presented. A mechanical extension has been developed that allows Phantom to operate at a safe distance, away from a high-density magnetic field of an fMRI scanner. A study presented in this paper has confirmed electromagnetic compatibility
Izvleček Izhodišča: Motnje v delovanju možganov so velika skupina nevroloških in psihiatričnih bo... more Izvleček Izhodišča: Motnje v delovanju možganov so velika skupina nevroloških in psihiatričnih bolezni. Skupaj pomenijo največji javnozdravstveni problem v Evropi in zahodnem svetu, saj predstavljajo tretjino vsega bolezenskega bremena družbe. Pojavljajo se pogosto in povzročajo tako akutne kot kronične okvare zdravja in upad v vsakdanjem delovanju bolnikov. O prvi raziskavi Evropskega sveta za možgane (angl. European Brain Council, EBC) o pomenu možganskih bolezni iz leta 2005 so v Zdravniškem vestniku že poročali, tokrat pa predstavljamo rezultate nove razširjene raziskave EBC iz leta 2010. Raziskava je zajela 19 večjih skupin možganskih bolezni v 30 evropskih državah s skupaj 514 milijoni prebivalcev (EU27 ter Islandija, Norveška in Švica). Z uporabo enakega metodološkega pristopa posamezne države sedaj predstavljajo njihove ocene tovrstnih stroškov. Prispevek podaja ocene stroškov motenj v delovanju možganov za Slovenijo v 2010.
Expression of acetylcholine receptors (AChRs) in the extrajunctional muscle regions, but not in t... more Expression of acetylcholine receptors (AChRs) in the extrajunctional muscle regions, but not in the neuromuscular junctions, is repressed by propagated electric activity in muscle fibers. During regeneration, subsynaptic-like specializations accumulating AChRs are induced in new myotubes by agrin attached to the synaptic basal lamina at the places of former motor endplates even in the absence of innervation. We examined whether AChRs still accumulated at these places when the regenerating muscles were ectopically innervated and the former synaptic places became extrajunctional. Rat soleus muscles were injured by bupivacaine and ischemia to produce complete myofiber degeneration. The soleus muscle nerve was permanently severed and the muscle was ectopically innervated by the peroneal nerve a few millimeters away from the former junctional region. After 4 weeks of regeneration, the muscles contracted upon nerve stimulation, showed little atrophy and the cross-section areas of their fibers were completely above the range in non-innervated regenerating muscles, indicating successful innervation. Subsynaptic-like specializations in the former junctional region still accumulated AChRs (and acetylcholinesterase) although no motor nerve endings were observed in their vicinity and the cross-section area of their fibers clearly demonstrated that they were ectopically innervated. We conclude that the expression of AChRs at the places of the former neuromuscular junctions in the ectopically innervated regenerated soleus muscles is activity-independent.
... Cerebral Cortex 12(8):877-882 9. Jensen O and Lisman JE (2005) Hippocampal sequence-encoding ... more ... Cerebral Cortex 12(8):877-882 9. Jensen O and Lisman JE (2005) Hippocampal sequence-encoding driven by a cortical multi-item working ... Vito Logar University of Ljubljana, Faculty of electrical engineering Trzaska 25, SI-1000 Ljubljana, Slovenia [email protected]
Whilst the act of sniffing can provide us with an indirect method to study the central mechanisms... more Whilst the act of sniffing can provide us with an indirect method to study the central mechanisms of respiratory control, functional neuroimaging now provides us with a tool to directly visualise the activity of the human brain during this voluntary action using functional magnetic resonance imaging (fMRI).
A 42-year-old man was evaluated for snoring and sleep apnea. Overnight polysomnography revealed 2... more A 42-year-old man was evaluated for snoring and sleep apnea. Overnight polysomnography revealed 28 events per hour on the apnea-hypopnea index. To determine the site of obstruction and determine treatment, dynamic MRI with concurrent EEG monitoring in natural sleep was performed. We recorded 2 mechanisms of total occlusion: at the oropharyngeal level and due to movement of the uvula during snoring (videos 1 and 2). 1 Two different mechanisms suggested against surgical therapy; he was treated with a continuous positive airway pressure mask at 7 cm H 2 O, with a good outcome.
Numerous reports have shown that performing working-memory tasks causes an elevated rhythmic coup... more Numerous reports have shown that performing working-memory tasks causes an elevated rhythmic coupling in different areas of the brain; it has been suggested that this indicates information exchange. Since the information exchanged is encoded in brain waves and measurable by electroencephalography (EEG) it is reasonable to assume that it can be extracted with an appropriate method. In our study we made an attempt to extract the information using an artificial neural network (ANN), which can be considered as a stimulus-response model with a state observer. The EEG was recorded from three subjects while they performed a modified Sternberg task that required them to respond to each task with the answer ''true'' or ''false''. The study revealed that a stimulus-response model can successfully be identified by observing phase-demodulated theta-band EEG signals 1 s prior to a subject's answer. The results also showed that it was possible to predict the answers from the EEG signals with an average reliability of 75% for all the subjects. From this we concluded that it is possible to observe the system states and thus predict the correct answer using the EEG signals as inputs.
gyri (BA 32,31), the inferior and middle frontal gyri (BA 6,9,10), the superior temporal sulcus a... more gyri (BA 32,31), the inferior and middle frontal gyri (BA 6,9,10), the superior temporal sulcus and the subcortical grey matter (caudate and thalamus). The critical cortical activations were found in the right-sided intraparietal sulcus (IPS), anterior cingulate cortex (ACC), and right-sided lateral prefrontal cortex (PFC). These three regions were entered into the DCM. Comparison on group level revealed superiority of dynamic causal models in which IPS and alternatively PFC served as input regions as compared to a model in which ACC is assumed to receive external inputs. No significant difference was observed between fully connected models with IPS (model 1) and PFC (model 2) as input regions. Subsequent analysis of intrinsic connectivity within two investigated models (1,2) disclosed significant parallel forward connections from IPS to the frontal areas (model 1) and from PFC to ACC and IPS (model 2).
using both systems. Examination with system B demonstrated larger area of echogenic SN than measu... more using both systems. Examination with system B demonstrated larger area of echogenic SN than measurements with system A (mean area ± SE: 15.4 ± 1.4 mm 2 vs.12.4 ± 1.2 mm 2 ; p = 0.00). Enlargement of echogenic SN area ( 3 20 mm 2 ) was found in 5 and 8 subjects using system A and B, respectively. SN size measured by system A and B ) correlated significantly (Spearman coefficient: 0.72; p = 0.00).
Background: The subject of brain-computer interfaces (BCIs) represents a vast and still mainly un... more Background: The subject of brain-computer interfaces (BCIs) represents a vast and still mainly undiscovered land, but perhaps the most interesting part of BCIs is trying to understand the information exchange and coding in the brain itself. According to some recent reports, the phase characteristics of the signals play an important role in the information transfer and coding. The mechanism of phase shifts, regarding the information processing, is also known as the phase coding of information. Objective: The authors would like to show that electroencephalographic (EEG) signals, measured during the performance of different gripping-force control tasks, carry enough information for the successful prediction of the gripping force, as applied by the subjects, when using a methodology based on the phase demodulation of EEG data. Since the presented methodology is non-invasive it could be used as an alternative approach for the development of BCIs. Materials and methods: In order to predict the gripping force from the EEG signals we used a methodology that uses subsequent signal processing methods: simplistic filtering methods, for extracting the appropriate brain rhythm; principal component analysis, for achieving the linear independence and detecting the source of the signal; and the phase-demodulation method, for extracting the phase-coded information about the gripping force. A fuzzy inference system is then used to predict the gripping force from the processed EEG data.
PHASE CODING OF INFORMATION IN THE HUMAN BRAIN Vito LOGARa , Igor KRJANCa , Ale BELIČa , Simon ... more PHASE CODING OF INFORMATION IN THE HUMAN BRAIN Vito LOGARa , Igor KRJANCa , Ale BELIČa , Simon BREANb ,Bla KORITNIKb , Janez ZIDARb a Faculty of Electrical Engineering, University of Ljubljana, Traka 25, SI-1000 Ljubljana ... [8] O. Jensen and CD ...
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