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Levy M, Zurawel M, d’Hardemare V, Moran A, Andelman F, Manor Y, Cohen J, Meshulam M, Balash Y, Gurevich T, Fried I, Bergman H. Subthalamic nucleus physiology is correlated with deep brain stimulation motor and non-motor outcomes. Brain Commun 2023; 5:fcad268. [PMID: 38025270 PMCID: PMC10664412 DOI: 10.1093/braincomms/fcad268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 04/24/2023] [Accepted: 10/17/2023] [Indexed: 12/01/2023] Open
Abstract
Subthalamic nucleus deep brain stimulation is commonly indicated for symptomatic relief of idiopathic Parkinson's disease. Despite the known improvement in motor scores, affective, cognitive, voice and speech functions might deteriorate following this procedure. Recent studies have correlated motor outcomes with intraoperative microelectrode recordings. However, there are no microelectrode recording-based tools with predictive values relating to long-term outcomes of integrative motor and non-motor symptoms. We conducted a retrospective analysis of the outcomes of patients with idiopathic Parkinson's disease who had subthalamic nucleus deep brain stimulation at Tel Aviv Sourasky Medical Centre (Tel Aviv, Israel) during 2015-2016. Forty-eight patients (19 women, 29 men; mean age, 58 ± 8 years) who were implanted with a subthalamic nucleus deep brain stimulation device underwent pre- and postsurgical assessments of motor, neuropsychological, voice and speech symptoms. Significant improvements in all motor symptoms (except axial signs) and levodopa equivalent daily dose were noted in all patients. Mild improvements were observed in more posterior-related neuropsychological functions (verbal memory, visual memory and organization) while mild deterioration was observed in frontal functions (personality changes, executive functioning and verbal fluency). The concomitant decline in speech intelligibility was mild and only partial, probably in accordance with the neuropsychological verbal fluency results. Acoustic characteristics were the least affected and remained within normal values. Dimensionality reduction of motor, neuropsychological and voice scores rendered six principal components that reflect the main clinical aspects: the tremor-dominant versus the rigidity-bradykinesia-dominant motor symptoms, frontal versus posterior neuropsychological deficits and acoustic characteristics versus speech intelligibility abnormalities. Microelectrode recordings of subthalamic nucleus spiking activity were analysed off-line and correlated with the original scores and with the principal component results. Based on 198 microelectrode recording trajectories, we suggest an intraoperative subthalamic nucleus deep brain stimulation score, which is a simple sum of three microelectrode recording properties: normalized neuronal activity, the subthalamic nucleus width and the relative proportion of the subthalamic nucleus dorsolateral oscillatory region. A threshold subthalamic nucleus deep brain stimulation score >2.5 (preferentially composed of normalized root mean square >1.5, subthalamic nucleus width >3 mm and a dorsolateral oscillatory region/subthalamic nucleus width ratio >1/3) predicts better motor and non-motor long-term outcomes. The algorithm presented here optimizes intraoperative decision-making of deep brain stimulation contact localization based on microelectrode recording with the aim of improving long-term (>1 year) motor, neuropsychological and voice symptoms.
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Dawidowicz L, L Ash E, Korczyn AD, Andelman F, Levy S, Elkana O. Can the RAVLT predict deterioration from MCI to dementia? Data from long term follow up. Exp Aging Res 2021; 47:347-356. [PMID: 33704020 DOI: 10.1080/0361073x.2021.1898182] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
OBJECTIVE To assess whether the Rey Auditory Verbal Learning Test (RAVLT) could differentiate deterioration from Mild Cognitive Impairment (MCI) to dementia. METHODS Twenty-six participants who were diagnosed with MCI performed the RAVLT and the Mini Mental State Examination (MMSE) at baseline and after nearly a decade (M = 8.8 years, SD = 3.16), in order to evaluate whether they progressed to dementia. RESULTS Twelve participants [5 males, 7 females; age M = 63.7 (7.7)] kept their diagnoses of MCI; 14 participants [11 males, 3 females; age M = 75.0 (6.5)] converted to dementia. Both groups had similar MMSE scores at baseline [26.6 (0.6); and 26.6 (0.7) respectively]. Significant differences between dementia and MCI groups were found on most measures of the RAVLT at baseline: Immediate memory [p = .04], delayed recall [p = .003], total learning [p = .01], learning rate [p = .002], retrieval efficiency [p = .004], and false alarms [p = .004]. Thus, the RAVLT results were significantly worse at baseline in those who later converted. The results remain the same when controlling for age. CONCLUSION The results extend previous findings with follow-up of nearly a decade demonstrating that most of the RAVLT measures are sensitive to differentiate conversion from MCI to dementia.
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Andelman-Gur MM, Gazit T, Andelman F, Kipervasser S, Kramer U, Neufeld MY, Fried I, Fahoum F. Spatial distribution and hemispheric asymmetry of electrically evoked experiential phenomena in the human brain. J Neurosurg 2020; 133:54-62. [PMID: 31200379 DOI: 10.3171/2019.3.jns183429] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 03/24/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Experiential phenomena (EP), such as illusions and complex hallucinations, are vivid experiences created in one's mind. They can occur spontaneously as epileptic auras or can be elicited by electrical brain stimulation (EBS) in patients undergoing presurgical evaluation for drug-resistant epilepsy. Previous work suggests that EP arise from activation of different nodes within interconnected neural networks mainly in the temporal lobes. Yet, the anatomical extent of these neural networks has not been described and the question of lateralization of EP has not been fully addressed. To this end, an extended number of brain regions in which electrical stimulation elicited EP were studied to test whether there is a lateralization propensity to EP phenomena. METHODS A total of 19 drug-resistant focal epilepsy patients who underwent EBS as part of invasive presurgical evaluation and who experienced EP during the stimulation were included. Spatial dispersion of visual and auditory illusions and complex hallucinations in each hemisphere was determined by calculation of Euclidean distances between electrodes and their centroid in common space, based on (x, y, z) Cartesian coordinates of electrode locations. RESULTS In total, 5857 stimulation epochs were analyzed; 917 stimulations elicited responses, out of which 130 elicited EP. Complex visual hallucinations were found to be widely dispersed in the right hemisphere, while they were tightly clustered in the occipital lobe of the left hemisphere. Visual illusions were elicited mostly in the occipital lobes bilaterally. Auditory illusions and hallucinations were evoked symmetrically in the temporal lobes. CONCLUSIONS These findings suggest that complex visual hallucinations arise from wider spread in the right compared to the left hemisphere, possibly mirroring the asymmetry in the white matter organization of the two hemispheres. These results offer some insights into lateralized differences in functional organization and connectivity that may be important for functional mapping and planning of surgical resections in patients with epilepsy.
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Andelman-Gur MM, Gazit T, Fahoum F, Andelman F, Fried I. Negative and positive volitional responses induced by stimulating the superior frontal gyrus: A case study. Brain Stimul 2019; 12:1614-1616. [PMID: 31474544 DOI: 10.1016/j.brs.2019.08.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 08/03/2019] [Accepted: 08/17/2019] [Indexed: 11/18/2022] Open
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Magidov E, Hayat H, Sharon O, Andelman F, Katzav S, Lavie P, Tauman R, Nir Y. Near-total absence of REM sleep co-occurring with normal cognition: an update of the 1984 paper. Sleep Med 2018; 52:134-137. [PMID: 30321820 DOI: 10.1016/j.sleep.2018.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 08/13/2018] [Accepted: 09/10/2018] [Indexed: 11/17/2022]
Abstract
BACKGROUND REM sleep (REMS) is considered vital for supporting well-being and normal cognition. However, it remains unclear if and how decreases in REMS impair cognitive abilities. Rare case studies of patients with REMS abolishment due to pontine lesions remain sporadic, and formal evaluation of cognitive status is lacking. In 1984, Lavie and colleagues described the case of Y.C. - a man with a pontine lesion and near-total absence of REMS who led a normal life. Here, we set out to re-evaluate this individual's REMS status 30 years after the original report, and formally assess his cognitive abilities. METHODS Four whole-night polysomnographic sleep recordings were conducted to evaluate sleep architecture. Sleep scoring was performed according to the American Academy of Sleep Medicine (AASM) guidelines. Cranial Computed Tomography (CT) imaging was performed, as well as formal neuropsychological testing to evaluate cognitive functions. RESULTS Y.C. averaged 4.5% of sleep time in REMS, corresponding to the 0.055 percentile of normal values for his age. Furthermore, residual REMS episodes were short and only occurred towards the end of the night. CT imaging revealed damage and metallic fragments in pons, cerebellum, and thalamus. Neuropsychological evaluation demonstrated average to high-average cognitive skills, normal memory, and motor difficulties including speech and left hand dyspraxia. CONCLUSIONS To our knowledge, this is the only case where REMS loss resulting from pontine lesion was re-evaluated after many years. We find a near-total absence of REMS with no signs of significant compensation throughout adult life, along with normal cognitive status. The results provide a unique perspective on the ongoing debate regarding the functional role of REMS in supporting cognition.
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Gazit T, Andelman F, Glikmann-Johnston Y, Gonen T, Solski A, Shapira-Lichter I, Ovadia M, Kipervasser S, Neufeld MY, Fried I, Hendler T, Perry D. Probabilistic machine learning for the evaluation of presurgical language dominance. J Neurosurg 2016; 125:481-93. [DOI: 10.3171/2015.7.jns142568] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE
Providing a reliable assessment of language lateralization is an important task to be performed prior to neurosurgery in patients with epilepsy. Over the last decade, functional MRI (fMRI) has emerged as a useful noninvasive tool for language lateralization, supplementing or replacing traditional invasive methods. In standard practice, fMRI-based language lateralization is assessed qualitatively by visual inspection of fMRI maps at a specific chosen activation threshold. The purpose of this study was to develop and evaluate a new computational technique for providing the probability of each patient to be left, right, or bilateral dominant in language processing.
METHODS
In 76 patients with epilepsy, a language lateralization index was calculated using the verb-generation fMRI task over a wide range of activation thresholds (from a permissive threshold, analyzing all brain regions, to a harsh threshold, analyzing only the strongest activations). The data were classified using a probabilistic logistic regression method.
RESULTS
Concordant results between fMRI and Wada lateralization were observed in 89% of patients. Bilateral and right-dominant groups showed similar fMRI lateralization patterns differentiating them from the left-dominant group but still allowing classification in 82% of patients.
CONCLUSIONS
These findings present the utility of a semi-supervised probabilistic learning approach for presurgical language-dominance mapping, which may be extended to other cognitive domains such as memory and attention.
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Singer N, Podlipsky I, Esposito F, Okon-Singer H, Andelman F, Kipervasser S, Neufeld MY, Goebel R, Fried I, Hendler T. Distinct iEEG activity patterns in temporal-limbic and prefrontal sites induced by emotional intentionality. Cortex 2014; 60:121-38. [PMID: 25288171 DOI: 10.1016/j.cortex.2014.07.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 04/09/2014] [Accepted: 07/29/2014] [Indexed: 12/30/2022]
Abstract
Our emotions tend to be directed towards someone or something. Such emotional intentionality calls for the integration between two streams of information; abstract hedonic value and its associated concrete content. In a previous functional magnetic resonance imaging (fMRI) study we found that the combination of these two streams, as modeled by short emotional music excerpts and neutral film clips, was associated with synergistic activation in both temporal-limbic (TL) and ventral-lateral PFC (vLPFC) regions. This additive effect implies the integration of domain-specific 'affective' and 'cognitive' processes. Yet, the low temporal resolution of the fMRI limits the characterization of such cross-domain integration. To this end, we complemented the fMRI data with intracranial electroencephalogram (iEEG) recordings from twelve patients with intractable epilepsy. As expected, the additive fMRI activation in the amygdala and vLPFC was associated with distinct spatio-temporal iEEG patterns among electrodes situated within the vicinity of the fMRI activation foci. On the one hand, TL channels exhibited a transient (0-500 msec) increase in gamma power (61-69 Hz), possibly reflecting initial relevance detection or hedonic value tagging. On the other hand, vLPFC channels showed sustained (1-12 sec) suppression of low frequency power (2.3-24 Hz), possibly mediating changes in gating, enabling an on-going readiness for content-based processing of emotionally tagged signals. Moreover, an additive effect in delta-gamma phase-amplitude coupling (PAC) was found among the TL channels, possibly reflecting the integration between distinct domain specific processes. Together, this study provides a multi-faceted neurophysiological signature for computations that possibly underlie emotional intentionality in humans.
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Meshulam M, Ramot M, Harel M, Kipervasser S, Andelman F, Neufeld MY, Kramer U, Fried I, Malach R. Selectivity of audiovisual ECoG responses revealed under naturalistic stimuli in the human cortex. J Neurophysiol 2013; 109:2272-81. [PMID: 23407355 DOI: 10.1152/jn.00474.2012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A fundamental debate in the study of cortical sensory systems concerns the scale of functional selectivity in cortical networks. Brain imaging studies have repeatedly demonstrated functional selectivity in entire cortical areas and networks using predetermined stimuli. However, it is not clear to what extent these networks are heterogeneous, i.e., whether the selectivity profiles in subregions within each sensory network show significant dissimilarity. Here, we studied local functional selectivity in the human cortex using naturalistic movie clips shown to 12 patients implanted with intracranial electrocorticography electrodes (590 in total), providing extensive cortical coverage. We examined the similarity of response profiles (40- to 80-Hz gamma-power modulations) across electrodes using a novel data driven approach without assuming any predefined category. Our results show that the functional selectivity of each highly responsive electrode was different from that of all other electrodes across the sensory cortex. Thus most responsive electrodes showed an activation profile that was unique in each patient and was similar to that of only 0.3% (1-2) of all other electrodes across all patients. Functional similarity between electrodes was linked to anatomical proximity. While in most electrodes the source of selectivity was complex, a small subset showed the well-documented selectivity to faces and actions. Our results indicate that the human sensory cortex is organized as a mosaic of functionally unique subregions in which each site manifests its own special response profile.
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Andelman F, Kipervasser S, Maimon S, Fried I, Parmet Y, Neufeld MY. A revised intracarotid etomidate memory (Wada) procedure. Acta Neurol Scand 2013; 127:97-102. [PMID: 22651814 DOI: 10.1111/j.1600-0404.2012.01685.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2012] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To evaluate unilateral memory function by the means of a modified Montreal etomidate speech and memory procedure (e-SAM) in epilepsy patients who were candidates for standard anterior temporal lobectomy involving resection of mesial temporal lobe structures. MATERIALS AND METHODS After the first three patients experienced significant side effects with the e-SAM procedure, we modified the procedure to a single bolus injection. The neuropsychological data of all 21 patients who underwent unilateral memory testing by means of intracarotid injection of etomidate were analyzed. RESULTS There was a significant difference in memory scores when injections were on the side ipsilateral to the epileptogenic focus compared with when the injections were on the contralateral side (P < 0.01), supposedly reflecting unilateral hippocampal memory function and dysfunction. In addition, the procedural modification resulted in eradication of all major side effects in the ensuing 18 patients. CONCLUSIONS The technical modification of the Montreal procedure from continuous to bolus injection effectively enabled the demonstration of the relative weakness of the memory function of the epileptogenic hemisphere. The revised etomidate procedure provided the clinical information on unilateral hippocampal memory function necessary for surgical decision.
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Rosenberg-Katz K, Jamshy S, Singer N, Podlipsky I, Kipervasser S, Andelman F, Neufeld MY, Intrator N, Fried I, Hendler T. Enhanced functional synchronization of medial and lateral PFC underlies internally-guided action planning. Front Hum Neurosci 2012; 6:79. [PMID: 22518101 PMCID: PMC3324921 DOI: 10.3389/fnhum.2012.00079] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Accepted: 03/21/2012] [Indexed: 11/15/2022] Open
Abstract
Actions are often internally guided, reflecting our covert will and intentions. The dorsomedial prefrontal cortex, including the pre-Supplementary Motor Area (pre-SMA), has been implicated in the internally generated aspects of action planning, such as choice and intention. Yet, the mechanism by which this area interacts with other cognitive brain regions such as the dorsolateral prefrontal cortex, a central node in decision-making, is still unclear. To shed light on this mechanism, brain activity was measured via fMRI and intracranial EEG in two studies during the performance of visually cued repeated finger tapping in which the choice of finger was guided by either a presented number (external) or self-choice (internal). A functional-MRI (fMRI) study in 15 healthy participants demonstrated that the pre-SMA, compared to the SMA proper, was more active and also more functionally correlated with the dorsolateral prefrontal cortex during internally compared to externally guided action planning (p < 0.05, random effect). In a similar manner, an intracranial-EEG study in five epilepsy patients showed greater inter-regional gamma-related connectivity between electrodes situated in medial and lateral aspects of the prefrontal cortex for internally compared to externally guided actions. Although this finding was observed for groups of electrodes situated both in the pre-SMA and SMA-proper, increased intra-cluster gamma-related connectivity was only observed for the pre-SMA (sign-test, p < 0.0001). Overall our findings provide multi-scale indications for the involvement of the dorsomedial prefrontal cortex, and especially the pre-SMA, in generating internally guided motor planning. Our intracranial-EEG results further point to enhanced functional connectivity between decision-making- and motor planning aspects of the PFC, as a possible neural mechanism for internally generated action planning.
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Hindi-Ling H, Kipervasser S, Neufeld MY, Andelman F, Nagar S, Chistik V, Veshchev I, Fried I, Kramer U. Epilepsy surgery in children compared to adults. Pediatr Neurosurg 2011; 47:180-5. [PMID: 22041475 DOI: 10.1159/000331568] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 08/04/2011] [Indexed: 11/19/2022]
Abstract
AIM The purpose of this study was to compare the frequency of various surgical techniques and surgical outcome between pediatric and adult populations that underwent epilepsy surgery by the same team. METHODS All patients who underwent epilepsy surgery at the Tel Aviv Medical Center between 1997 and 2006 and had been followed up for >2 years were eligible for this study. The majority (90%) of all epilepsy surgeries carried out in Israel were performed in this institution and by a single neurosurgeon. Only patients that underwent video-EEG monitoring as part of the presurgical evaluation were included in the study. RESULTS A total of 186 patients (131 adults and 55 children) underwent epilepsy surgery in our institute during the study period, and follow-up was available for 177 patients (95%). While the adults underwent significantly more temporal lobe resections (51 vs. 20%, p < 0.0001), the children had significantly more extra-temporal non-lesional resections (18 vs. 1%, p < 0.0001) and hemispherectomies (5 vs. 1%, p = 0.002). Over one half (54%) of all the patients had a postoperative reduction in seizures of >90%, and 72% had a reduction of >50%, with no group difference in surgical success. Among the lesionectomies, the outcome was better for tumors, especially those in the temporal lobe. Only 1% of the patients had a long-term neurological deficit. CONCLUSIONS Children comprised 30% of the epilepsy surgical cases during the study period. Children underwent more non-lesional resections and hemispherectomies, while adults underwent more temporal lobe resections. There was no age-related difference in surgical outcome.
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Andelman F, Hoofien D, Goldberg I, Aizenstein O, Neufeld MY. Bilateral hippocampal lesion and a selective impairment of the ability for mental time travel. Neurocase 2010; 16:426-35. [PMID: 20401802 DOI: 10.1080/13554791003623318] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Mental time travel allows individuals to mentally project themselves backwards and forwards in subjective time. This case report describes a young woman suddenly rendered amnesic as a result of bilateral hippocampal damage following an epileptic seizure and brain anoxia. Her neuropsychological profile was characterized by a high-average general level of cognitive functioning, selective deficit in episodic memory of past events and a significant difficulty to envisage her personal future. This case provides clinical support for the concept of mental time travel with its retrospective and prospective components and for the hippocampus being its critical neural substrate.
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Privman E, Fisch L, Neufeld MY, Kramer U, Kipervasser S, Andelman F, Yeshurun Y, Fried I, Malach R. Antagonistic relationship between gamma power and visual evoked potentials revealed in human visual cortex. ACTA ACUST UNITED AC 2010; 21:616-24. [PMID: 20624838 DOI: 10.1093/cercor/bhq128] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Scalp electroencephalography and magnetoencephalography studies have revealed a rapid evoked potential "adaptation" where one visual stimulus suppresses the event-related potential (ERP) of the second stimulus. Here, we investigated a similar effect revealed in subdural intracranial recordings in humans. Our results show that the suppression of the subdural ERP is not associated with a reduction in the gamma frequency power, considered to reflect the underlying neural activity. Furthermore, the evoked potential suppression (EPS) phenomenon was not reflected in recognition behavior of the patients. Rather, the EPS was tightly linked to the level of gamma activity preceding the event, and this effect was independent of the interstimulus time interval. Analyzing other frequency bands failed to reveal a similar link. Our results thus show a consistent antagonism between subdural ERP and gamma power although both are considered markers for neural activity. We hypothesize that the ERP suppression is due to a desynchronization of neuronal firing resulting from recurrent neural activity in the vicinity of the freshly stimulated neurons and not an attenuation of the overall neural activity.
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Fisch L, Privman E, Ramot M, Harel M, Nir Y, Kipervasser S, Andelman F, Neufeld MY, Kramer U, Fried I, Malach R. Neural "ignition": enhanced activation linked to perceptual awareness in human ventral stream visual cortex. Neuron 2009; 64:562-74. [PMID: 19945397 DOI: 10.1016/j.neuron.2009.11.001] [Citation(s) in RCA: 188] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2009] [Indexed: 12/21/2022]
Abstract
Human recognition performance is characterized by abrupt changes in perceptual states. Understanding the neuronal dynamics underlying such transitions could provide important insights into mechanisms of recognition and perceptual awareness. Here we examined patients monitored for clinical purposes with multiple subdural electrodes. The patients participated in a backward masking experiment in which pictures of various object categories were presented briefly followed by a mask. We recorded ECoG from 445 electrodes placed in 11 patients. We found a striking increase in gamma power (30-70 Hz) and evoked responses specifically associated with successful recognition. The enhanced activation occurred 150-200 ms after stimulus onset and consistently outlasted the stimulus presentation. We propose that the gamma and evoked potential activations reflect a rapid increase in recurrent neuronal activity that plays a critical role in the emergence of a recognizable visual percept in conscious awareness.
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Auriel E, Landov H, Blatt I, Theitler J, Gandelman-Marton R, Chistik V, Margolin N, Gross B, Parmet Y, Andelman F, Neufeld MY. Quality of life in seizure-free patients with epilepsy on monotherapy. Epilepsy Behav 2009; 14:130-3. [PMID: 18926930 DOI: 10.1016/j.yebeh.2008.09.027] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Revised: 09/23/2008] [Accepted: 09/23/2008] [Indexed: 11/29/2022]
Abstract
Epilepsy is a multifaceted chronic disorder which has diverse and complex effects on the well-being of the patient. Although it is evident that seizure type and frequency play a critical role in the quality of life (QOL) of patients with epilepsy, it is less clear what the major determinants are that influence QOL in seizure-free patients receiving monotherapy. The aim of this study was to evaluate demographic, clinical, and socioeconomic factors influencing the QOL of seizure-free patients receiving monotherapy. All participants were patients from four medical centers who had epilepsy, were on monotherapy, and had been seizure-free for at least 1 year. Responders completed three questionnaires on demographic and clinical information, QOL, and antiepileptic drug (AED) side effects during routine follow-up visits in the epilepsy clinics. We present the data of 103 patients: 59 females (57.3%), mean age 37.75+/-13.66 years. Treatment side effects and unemployment (p<0.0001, p=0.037, respectively) were significant predictors for poor overall QOL, whereas age, gender, education, family status, comorbidity, seizure type, age of seizure onset, and epilepsy duration did not significantly affect overall QOL. There was no significant difference in side effects and QOL between patients receiving older versus newer AEDs. Ninety-four (92.2%) patients reported experiencing at least one side effect of AEDs when queried about specific symptoms, while only 11 (10.7%) patients replied affirmatively when asked whether they experienced "any" side effects. The most common side effects involved the central nervous system. In conclusion, this study reveals that the most significant factor influencing the QOL in seizure-free patients on monotherapy is AED side effects. QOL is a crucial component in the clinical care of patients with epilepsy, and physicians should take the time to ask specific questions on side effects of AEDs.
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Nir Y, Mukamel R, Dinstein I, Privman E, Harel M, Fisch L, Gelbard-Sagiv H, Kipervasser S, Andelman F, Neufeld MY, Kramer U, Arieli A, Fried I, Malach R. Interhemispheric correlations of slow spontaneous neuronal fluctuations revealed in human sensory cortex. Nat Neurosci 2008; 11:1100-8. [PMID: 19160509 PMCID: PMC2642673 DOI: 10.1038/nn.2177] [Citation(s) in RCA: 372] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Animal studies have shown robust electrophysiological activity in the sensory cortex in the absence of stimuli or tasks. Similarly, recent human functional magnetic resonance imaging (fMRI) revealed widespread, spontaneously emerging cortical fluctuations. However, it is unknown what neuronal dynamics underlie this spontaneous activity in the human brain. Here we studied this issue by combining bilateral single-unit, local field potentials (LFPs) and intracranial electrocorticography (ECoG) recordings in individuals undergoing clinical monitoring. We found slow (<0.1 Hz, following 1/f-like profiles) spontaneous fluctuations of neuronal activity with significant interhemispheric correlations. These fluctuations were evident mainly in neuronal firing rates and in gamma (40-100 Hz) LFP power modulations. Notably, the interhemispheric correlations were enhanced during rapid eye movement and stage 2 sleep. Multiple intracranial ECoG recordings revealed clear selectivity for functional networks in the spontaneous gamma LFP power modulations. Our results point to slow spontaneous modulations in firing rate and gamma LFP as the likely correlates of spontaneous fMRI fluctuations in the human sensory cortex.
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Kipervasser S, Palti D, Neufeld MY, Ben Shachar M, Andelman F, Fried I, Korczyn AD, Hendler T. Possible remote functional reorganization in left temporal lobe epilepsy. Acta Neurol Scand 2008; 117:324-31. [PMID: 18005219 DOI: 10.1111/j.1600-0404.2007.00948.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To provide functional magnetic resonance imaging-based insight into the impact of left temporal lobe epilepsy (TLE) on language-related functional re-organization. MATERIALS AND METHODS Ten right-handed patients with left TLE were compared with 10 matched healthy controls. Regional brain activation during the language task was measured in the inferior frontal gyrus (IFG) and in the superior temporal gyrus (STG), and the regional inter-hemispheric lateralization index (LI) was calculated. RESULTS Left language lateralization was documented in all the patients and controls. Reduced lateralization in the IFG was due to decreased activity in the left frontal region rather than to increased activity in the right frontal region. The LI values in the STG correlated with the LI values in the IFG in the controls but not in the patients. CONCLUSIONS The left IFG was most probably involved in the epileptogenesis and concomitant language-related cortical plasticity in patients with left TLE.
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Rosenberg K, Liebling R, Avidan G, Perry D, Siman-Tov T, Andelman F, Ram Z, Fried I, Hendler T. Language related reorganization in adult brain with slow growing glioma: fMRI prospective case-study. Neurocase 2008; 14:465-73. [PMID: 19012166 DOI: 10.1080/13554790802459486] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
One possible mechanism for language plasticity in cases of lesions in left dominant hemisphere is the recruitment of homologous region in the unaffected non-dominant hemisphere. The potential of the right hemisphere to carry out such plasticity is expressed by the functional outcome of patients with lesions in the left hemisphere acquired at childhood prior to language acquisition. Whether lesions in the dominant hemisphere acquired in adulthood can result in functional recovery of language by means of recruitment of the non-dominant hemisphere is undetermined. We describe a 28-year-old, right-handed male diagnosed with a left temporo-frontal glioma. It was decided to manage him expectantly due to the low level of suspicion of malignancy and the close proximity of the lesion to critical language function centers. Language functional MRI (fMRI) tests were performed twice within the ensuing 2 years before surgical intervention. Regional brain activation was measured within the temporal and frontal lobes. Laterality index (LI) was calculated based on the corresponding number of activated voxels. The main finding is that over time, prior to resection of the enlarged tumor, the inferior frontal gyrus (IFG) changed from being strongly left lateralized in the first fMRI exam to being bilateral in the second fMRI exam, mainly due to larger activation in the right hemisphere. By that time, although the patient was not aphasic, his language performance was significantly below average. These findings suggest that a slow growing tumor in an adult language-related area might result in a functional reorganization by recruiting the right hemisphere. However, the contribution of such reorganization to the preservation of language performance remains equivocal.
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Privman E, Nir Y, Kramer U, Kipervasser S, Andelman F, Neufeld MY, Mukamel R, Yeshurun Y, Fried I, Malach R. Enhanced category tuning revealed by intracranial electroencephalograms in high-order human visual areas. J Neurosci 2007; 27:6234-42. [PMID: 17553996 PMCID: PMC6672161 DOI: 10.1523/jneurosci.4627-06.2007] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2006] [Revised: 04/05/2007] [Accepted: 04/27/2007] [Indexed: 11/21/2022] Open
Abstract
The functional organization of human sensory cortex was studied by comparing intracranial EEG (iEEG) recordings of local field potentials in neurosurgical patients with functional magnetic resonance imaging (fMRI) obtained in healthy subjects. Using naturalistic movie stimuli, we found a tight correlation between these two measures throughout the human sensory cortex. Importantly, the correlation between the iEEG and fMRI signals was site-specific, exhibiting neuroanatomically specific coupling. In several cortical sites the iEEG activity was confined strictly to one object category. This site selectivity was not limited to faces but included other object categories such as houses and tools. The selectivity of the iEEG signals to images of different object categories was remarkably higher when compared with the selectivity of the corresponding fMRI signals. A plausible interpretation of the fMRI and iEEG results concerns cortical organization in which object categories are organized in a mosaic of narrowly tuned object-selective clusters.
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Andelman F, Kipervasser S, Reider-Groswasser II, Fried I, Neufeld MY. Hippocampal memory function as reflected by the intracarotid sodium methohexital Wada test. Epilepsy Behav 2006; 9:579-86. [PMID: 16938491 DOI: 10.1016/j.yebeh.2006.08.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 07/29/2006] [Accepted: 08/02/2006] [Indexed: 11/29/2022]
Abstract
The intracarotid amobarbital procedure (IAP) determines lateralization of memory function for predicting the risk of amnesia after epilepsy surgery. Shortages of amobarbital led to its substitution with sodium methohexital in the intracarotid methohexital procedure (IMP). We compared IAP scores (32 patients) with IMP scores (20 patients). Wada ipsilateral and contralateral memory scores were analyzed and compared, as was the relationship of these scores to the results of standard neuropsychological memory tests. There was no significant difference in Wada contralateral memory scores (first injection) between the IAP and IMP. Differences between the IAP and IMP in memory scores for the hemisphere ipsilateral to the epileptogenic focus (second injection) were significant (P=0.01), patients who underwent the IMP manifesting a higher ipsilateral memory reserve. IAP scores related better to standard neuropsychological memory test scores than did IMP scores. The anesthetic drug used in Wada testing may affect lateralized memory assessment and prediction of postsurgical memory changes.
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Bleich-Cohen M, Mintz M, Pianka P, Andelman F, Rotshtein P, Hendler T. Differential stimuli and task effects in the amygdala and sensory areas. Neuroreport 2006; 17:1391-5. [PMID: 16932145 DOI: 10.1097/01.wnr.0000215772.68979.f4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Whether the amygdala responds in a stimulus- or a task-specific way, and how it corresponds to such effects in sensory cortices is dubious. Eighteen volunteers participated in a functional magnetic resonance imaging study in which they were asked to identify either emotion or gender in visually presented scenes, faces, and sentences. Amygdala and the lateral occipital complex showed similar stimulus effect with greater activation to scenes than to faces and sentences, whereas the superior temporal complex responded preferentially to sentences. No task effect was observed in the amygdala, whereas lateral occipital complex and superior temporal complex showed left lateralized selectivity to the emotional task. These results suggest that the amygdala is more sensitive to stimulus than explicit task parameters when processing emotion.
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Andelman F, Kipervasser S, Neufeld MY, Kramer U, Fried I. Predictive value of Wada memory scores on postoperative learning and memory abilities in patients with intractable epilepsy. J Neurosurg 2006; 104:20-6. [PMID: 16509143 DOI: 10.3171/jns.2006.104.1.20] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Surgery for refractory epilepsy often bestows significant relief but may cause memory impairment. The risk of postoperative memory loss can be determined by the intracarotid amobarbital procedure, or the Wada test. Chemical inactivation of the hemisphere on the side of the lesion is usually performed first, followed by inactivation of the contralateral hemisphere. Patients who demonstrate adequate memory capacity of the contralateral hemisphere following deactivation of the ipsilateral hemisphere are considered good candidates for anterior temporal lobectomy. Evidence for the contribution of deactivating the contralateral healthy hemisphere remains inconclusive. METHODS The authors analyzed results in 32 patients with intractable epilepsy who had undergone a bilateral Wada test followed by an anterior temporal lobectomy and in whom the findings of both pre- and postsurgical neuropsychological evaluations were available. The Wada memory scores were correlated with the difference in scores between pre- and postsurgical standardized memory test scores. CONCLUSIONS Analyses revealed no significant relationship between the Wada memory scores in the contralateral hemisphere and postsurgical changes in memory abilities. There was, however, a significant negative correlation between the Wada memory score in the ipsilateral hemisphere and postsurgical memory changes, particularly in patients with right hemisphere epileptogenic lesions (p = 0.0007). The results of this study are discussed vis-à-vis two theories of hippocampal function, and the authors stress the importance of the functional status of the surgical hemisphere in the prediction of postsurgical memory changes.
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Kramer U, Kipervasser S, Neufeld MY, Fried I, Nagar S, Andelman F. Is there any correlation between severity of epilepsy and cognitive abilities in patients with temporal lobe epilepsy? Eur J Neurol 2006; 13:130-4. [PMID: 16490042 DOI: 10.1111/j.1468-1331.2006.01141.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Frequent refractory seizures may cause cognitive deterioration when they present at an early age, especially in infants. The findings of previous studies designed to examine the impact of repetitive seizures on cognition in adolescents and adults, however, have shown wide variation. We analyzed the data of neuropsychological evaluations of patients before they underwent temporal lobe resection because of refractory seizure disorder in our institution from 1998 to 2001. Forty-four consecutive patients aged 12-48 years underwent a comprehensive neuropsychological evaluation that included a battery of selected visual and verbal memory tests. Statistical analysis revealed no significant correlation between disease-related parameters, such as age of onset, duration of active disease, estimated cumulative number of complex partial seizures and secondarily generalized seizures, and the results of neuropsychological tests. These findings support the hypothesis that factors other than repetitive seizures are responsible for cognitive dysfunction among adolescents and adults.
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Andelman F, Zuckerman-Feldhay E, Hoffien D, Fried I, Neufeld MY. Lateralization of Deficit in Self-Awareness of Memory in Patients with Intractable Epilepsy. Epilepsia 2004; 45:826-33. [PMID: 15230708 DOI: 10.1111/j.0013-9580.2004.51703.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE Memory disorders are prominent among patients with intractable epilepsy. It has, however, been frequently observed that subjective memory complaints of these patients did not match their performance on objective memory tests. This discrepancy may reflect emotional, cognitive, or self-awareness deficits among these individuals. The aim of the current study was to explore the interference of cerebral dysfunction on accuracy of self-appraisal for memory. METHODS The degree of concordance between self-perception of memory function, as measured by a visual analogue scale, and actual performance on memory tests was computed in 35 patients who were candidates for epilepsy surgery and demographically matched normal control subjects. The difference between the self-estimated memory ability and performance on memory tests and its relation to the laterality of an epileptogenic lesion, cognitive factors, and affective status was then examined. RESULTS The results show that the discrepancy between the self-estimated memory ability and performance on memory tests in patients with right hemisphere epileptogenic lesions was significantly larger in magnitude compared with that in patients with left hemisphere lesions and demographically matched control subjects (p = 0.001). Furthermore, whereas patients with left hemisphere lesions and normal controls had about an equal number of positive and negative discrepancy scores, all patients with right hemisphere lesions had positive discrepancy scores, suggesting a tendency for overestimation of memory abilities. CONCLUSIONS These results suggest that right hemisphere lesions may introduce a systematic bias in self-awareness for memory. This bias may color patients' perceptions of self and others, affecting their perceptions of the quality of life, and necessitating an adjustment of the treatment goals and procedures.
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