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Romero MC, Davare M, Armendariz M, Janssen P. Neural effects of transcranial magnetic stimulation at the single-cell level. Nat Commun 2019; 10:2642. [PMID: 31201331 PMCID: PMC6572776 DOI: 10.1038/s41467-019-10638-7] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 05/17/2019] [Indexed: 11/09/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) can non-invasively modulate neural activity in humans. Despite three decades of research, the spatial extent of the cortical area activated by TMS is still controversial. Moreover, how TMS interacts with task-related activity during motor behavior is unknown. Here, we applied single-pulse TMS over macaque parietal cortex while recording single-unit activity at various distances from the center of stimulation during grasping. The spatial extent of TMS-induced activation is remarkably restricted, affecting the spiking activity of single neurons in an area of cortex measuring less than 2 mm in diameter. In task-related neurons, TMS evokes a transient excitation followed by reduced activity, paralleled by a significantly longer grasping time. Furthermore, TMS-induced activity and task-related activity do not summate in single neurons. These results furnish crucial experimental evidence for the neural effects of TMS at the single-cell level and uncover the neural underpinnings of behavioral effects of TMS. Transcranial Magnetic Stimulation (TMS) can modulate human brain activity, but the extent of the cortical area activated by TMS is unclear. Here, the authors show that TMS affects monkey single neuron activity in an area less than 2 mm diameter, while TMS-induced activity and task-related activity do not summate.
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Romero M, Janssen P, Davare M. Neural effects of continuous theta-burst stimulation on single neurons in macaque parietal cortex. Brain Stimul 2019. [DOI: 10.1016/j.brs.2018.12.587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Decramer T, Premereur E, Lagae L, van Loon J, Janssen P, Sunaert S, Theys T. Patient MW: transient visual hemi-agnosia. J Neurol 2019; 266:691-698. [DOI: 10.1007/s00415-019-09188-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 12/21/2018] [Accepted: 01/03/2019] [Indexed: 02/05/2023]
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Merken L, Romero M, Janssen P, Davare M. Behavioural effect of continuous Theta Burst Stimulation in macaque parietal cortex. Front Neurosci 2019. [DOI: 10.3389/conf.fnins.2019.96.00075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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De Schrijver S, Premereur E, Decramer T, Janssen P. Multichannel recordings in dorsal and ventral premotor cortex during a reach-to-grasp task. Front Neurosci 2019. [DOI: 10.3389/conf.fnins.2019.96.00058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Alizadeh AM, Van Dromme IC, Janssen P. Single-cell responses to three-dimensional structure in a functionally defined patch in macaque area TEO. J Neurophysiol 2018; 120:2806-2818. [PMID: 30230993 DOI: 10.1152/jn.00198.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Both dorsal and ventral visual pathways harbor several areas sensitive to gradients of binocular disparity (i.e., higher-order disparity). Although a wealth of information exists about disparity processing in early visual (V1, V2, and V3) and end-stage areas, TE in the ventral stream, and the anterior intraparietal area (AIP) in the dorsal stream, little is known about midlevel area TEO in the ventral pathway. We recorded single-unit responses to disparity-defined curved stimuli in a functional magnetic resonance imaging (fMRI) activation elicited by curved surfaces compared with flat surfaces in the macaque area TEO. This fMRI activation contained a small proportion of disparity-selective neurons, with very few of them second-order disparity selective. Overall, this population of TEO neurons did not preserve its three-dimensional structure selectivity across positions in depth, indicating a lack of higher-order disparity selectivity, but showed stronger responses to flat surfaces than to curved surfaces, as predicted by the fMRI experiment. The receptive fields of the responsive TEO cells were relatively small and generally foveal. A linear support vector machine classifier showed that this population of disparity-selective TEO neurons contains reliable information about the sign of curvature and the position in depth of the stimulus. NEW & NOTEWORTHY We recorded in a part of the macaque area TEO that is activated more by curved surfaces than by flat surfaces at different disparities using the same stimuli. In contrast to previous studies, this functional magnetic resonance imaging-defined patch did not contain a large number of higher-order disparity-selective neurons. However, a linear support vector machine could reliably classify both the sign of the disparity gradient and the position in depth of the stimuli.
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Goelen N, Morales J, Varon C, Van Huffel S, Augustijns P, Mols R, Vanuytsel T, de Hoon J, Herbots M, Tack J, Janssen P. Opening the black box: Gastric motility, as assessed by the novel vipun gastric monitoring system, is a surrogate measurement for gastric emptying. Clin Nutr 2018. [DOI: 10.1016/j.clnu.2018.06.1173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Caprara I, Janssen P, Romero MC. Investigating Object Representations in the Macaque Dorsal Visual Stream Using Single-unit Recordings. J Vis Exp 2018. [PMID: 30124646 DOI: 10.3791/57745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Previous studies have shown that neurons in parieto-frontal areas of the macaque brain can be highly selective for real-world objects, disparity-defined curved surfaces, and images of real-world objects (with and without disparity) in a similar manner as described in the ventral visual stream. In addition, parieto-frontal areas are believed to convert visual object information into appropriate motor outputs, such as the pre-shaping of the hand during grasping. To better characterize object selectivity in the cortical network involved in visuomotor transformations, we provide a battery of tests intended to analyze the visual object selectivity of neurons in parieto-frontal regions.
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Cleeren E, Casteels C, Goffin K, Koole M, Van Laere K, Janssen P, Van Paesschen W. Positron emission tomography imaging of cerebral glucose metabolism and type 1 cannabinoid receptor availability during temporal lobe epileptogenesis in the amygdala kindling model in rhesus monkeys. Epilepsia 2018; 59:959-970. [DOI: 10.1111/epi.14059] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2018] [Indexed: 01/31/2023]
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Sinnathamby G, Henderson G, Umair S, Janssen P, Bland R, Simpson H. Correction: The bacterial community associated with the sheep gastrointestinal nematode parasite Haemonchus contortus. PLoS One 2018. [PMID: 29529069 PMCID: PMC5846782 DOI: 10.1371/journal.pone.0194378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Sinnathamby G, Henderson G, Umair S, Janssen P, Bland R, Simpson H. The bacterial community associated with the sheep gastrointestinal nematode parasite Haemonchus contortus. PLoS One 2018; 13:e0192164. [PMID: 29420571 PMCID: PMC5805237 DOI: 10.1371/journal.pone.0192164] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 01/17/2018] [Indexed: 11/23/2022] Open
Abstract
Culture-independent methods were used to study the microbiota of adult worms, third-stage larvae and eggs, both in faeces and laid in vitro, of Haemonchus contortus, a nematode parasite of the abomasa of ruminants which is a major cause of production losses and ill-health. Bacteria were identified in eggs, the female reproductive tract and the gut of adult and third-stage larvae (L3). PCR amplification of 16S rRNA sequences, denaturing gradient gel electrophoresis (DGGE) and clone libraries were used to compare the composition of the microbial communities of the different life-cycle stages of the parasites, as well as parasites and their natural environments. The microbiomes of adult worms and L3 were different from those in the abomasum or faeces respectively. The H. contortus microbiota was mainly comprised of members of the phyla Proteobacteria, Firmicutes and Bacteroidetes. Bacteria were localised in the gut, inside eggs and within the uterus of adult female worms using the universal FISH Eub338 probe, which targets most bacteria, and were also seen in these tissues by light and transmission electron microscopy. Streptococcus/Lactococcus sp. were identified within the distal uterus with the probe Strc493. Sequences from the genera Weissella and Leuconostoc were found in all life-cycle stages, except eggs collected from faeces, in which most sequences belonged to Clostridium sp. Bacteria affiliated with Weissella/Leuconostoc were identified in both PCR-DGGE short sequences and clone libraries of nearly full length 16S rRNA bacterial sequences in all life-cycle stages and subsequently visualised in eggs by fluorescent in situ hybridisation (FISH) with group-specific probes. This strongly suggests they are vertically transmitted endosymbionts. As this study was carried out on a parasite strain which has been maintained in the laboratory, other field isolates will need to be examined to establish whether these bacteria are more widely dispersed and have potential as targets to control H. contortus infections.
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Alizadeh AM, Van Dromme I, Verhoef BE, Janssen P. Caudal Intraparietal Sulcus and three-dimensional vision: A combined functional magnetic resonance imaging and single-cell study. Neuroimage 2018; 166:46-59. [DOI: 10.1016/j.neuroimage.2017.10.045] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 09/28/2017] [Accepted: 10/21/2017] [Indexed: 11/30/2022] Open
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Romero M, Janssen P, Davare M. Neural effects of continuous Theta-Burst Stimulation on single neurons in macaque parietal cortex. Front Neurosci 2018. [DOI: 10.3389/conf.fnins.2018.95.00019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Verhoef BE, Vogels R, Janssen P. Binocular depth processing in the ventral visual pathway. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0259. [PMID: 27269602 DOI: 10.1098/rstb.2015.0259] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2016] [Indexed: 11/12/2022] Open
Abstract
One of the most powerful forms of depth perception capitalizes on the small relative displacements, or binocular disparities, in the images projected onto each eye. The brain employs these disparities to facilitate various computations, including sensori-motor transformations (reaching, grasping), scene segmentation and object recognition. In accordance with these different functions, disparity activates a large number of regions in the brain of both humans and monkeys. Here, we review how disparity processing evolves along different regions of the ventral visual pathway of macaques, emphasizing research based on both correlational and causal techniques. We will discuss the progression in the ventral pathway from a basic absolute disparity representation to a more complex three-dimensional shape code. We will show that, in the course of this evolution, the underlying neuronal activity becomes progressively more bound to the global perceptual experience. We argue that these observations most probably extend beyond disparity processing per se, and pertain to object processing in the ventral pathway in general. We conclude by posing some important unresolved questions whose answers may significantly advance the field, and broaden its scope.This article is part of the themed issue 'Vision in our three-dimensional world'.
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Devenport S, Penton C, Salgado N, Wang H, Flanigan K, Janssen P, Montanaro F. Reduced Hedgehog signalling in Duchenne muscular dystrophy impairs muscle regeneration and function. Neuromuscul Disord 2017. [DOI: 10.1016/s0960-8966(17)30255-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Janssen P, Verhoef BE, Premereur E. Functional interactions between the macaque dorsal and ventral visual pathways during three-dimensional object vision. Cortex 2017; 98:218-227. [PMID: 28258716 DOI: 10.1016/j.cortex.2017.01.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 01/23/2017] [Accepted: 01/25/2017] [Indexed: 11/18/2022]
Abstract
The division of labor between the dorsal and the ventral visual stream in the primate brain has inspired numerous studies on the visual system in humans and in nonhuman primates. However, how and under which circumstances the two visual streams interact is still poorly understood. Here we review evidence from anatomy, modelling, electrophysiology, electrical microstimulation (EM), reversible inactivation and functional imaging in the macaque monkey aimed at clarifying at which levels in the hierarchy of visual areas the two streams interact, and what type of information might be exchanged between the two streams during three-dimensional (3D) object viewing. Neurons in both streams encode 3D structure from binocular disparity, synchronized activity between parietal and inferotemporal areas is present during 3D structure categorization, and clusters of 3D structure-selective neurons in parietal cortex are anatomically connected to ventral stream areas. In addition, caudal intraparietal cortex exerts a causal influence on 3D-structure related activations in more anterior parietal cortex and in inferotemporal cortex. Thus, both anatomical and functional evidence indicates that the dorsal and the ventral visual stream interact during 3D object viewing.
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Alizadeh AM, Janssen P. Functional magnetic resonance imaging (fMRI) - guided single unit recordings reveal higher order disparity selectivity in area PIP of the macaque brain. Front Neurosci 2017. [DOI: 10.3389/conf.fnins.2017.94.00019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Premereur E, Janssen P, Vanduffel W. Functional MRI of macaque monkeys during task switching. Front Neurosci 2017. [DOI: 10.3389/conf.fnins.2017.94.00022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Premereur E, Taubert J, Janssen P, Vogels R, Vanduffel W. Effective Connectivity Reveals Largely Independent Parallel Networks of Face and Body Patches. Curr Biol 2016; 26:3269-3279. [DOI: 10.1016/j.cub.2016.09.059] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/04/2016] [Accepted: 09/28/2016] [Indexed: 10/20/2022]
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Janssen P. The functional organization of the intraparietal sulcus in the macaque monkey. J Vis 2016. [DOI: 10.1167/16.12.1302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Janssen P, Melenhorst J, Breukink S, Temel Y. EP 94. Fecal incontinence treated by sacral neuromodulation: Worldwide largest single center study. Clin Neurophysiol 2016. [DOI: 10.1016/j.clinph.2016.05.142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Deloose E, Janssen P, Lannoo M, Van der Schueren B, Depoortere I, Tack J. Higher plasma motilin levels in obese patients decrease after Roux-en-Y gastric bypass surgery and regulate hunger. Gut 2016; 65:1110-8. [PMID: 25986945 DOI: 10.1136/gutjnl-2015-309242] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/30/2015] [Indexed: 12/08/2022]
Abstract
OBJECTIVE Motilin-induced phase III contractions of the migrating motor complex (MMC) signal hunger in healthy volunteers. The current aim was to study the role of motilin as a hunger-inducing factor in obese patients and to evaluate the effect of Roux-en-Y gastric bypass (RYGB) surgery on plasma motilin levels and hunger scores. DESIGN Motilin and ghrelin plasma levels were determined during a complete MMC cycle in controls and obese patients selected for RYGB before, 6 months and 1 year after surgery. 20 min after the end of the second phase III, obese patients received an intravenous infusion of 40 mg erythromycin. Hunger was scored every 5 min. Hedonic hunger was assessed in obese patients with the Power of Food Scale questionnaire. RESULTS Obesity caused a switch in the origin of phase III from antrum to duodenum. Obese patients had significantly higher motilin levels compared with controls during the MMC but tended to lack the motilin peak prior to phase III necessary to trigger hunger. Hunger scores during phase III were significantly lower in obese patients, but could be restored to control levels through the administration of a low dose of the motilin agonist, erythromycin. After RYGB surgery motilin, but not ghrelin, levels decreased in parallel with hedonic hunger scores. CONCLUSIONS Motilin may be an important regulator involved in the pathogenesis of obesity.
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Cleeren E, Premereur E, Casteels C, Goffin K, Janssen P, Van Paesschen W. The effective connectivity of the seizure onset zone and ictal perfusion changes in amygdala kindled rhesus monkeys. NEUROIMAGE-CLINICAL 2016; 12:252-61. [PMID: 27489773 PMCID: PMC4959940 DOI: 10.1016/j.nicl.2016.05.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 04/04/2016] [Accepted: 05/31/2016] [Indexed: 12/22/2022]
Abstract
Epileptic seizures are network-level phenomena. Hence, epilepsy may be regarded as a circuit-level disorder that cannot be understood outside this context. Better insight into the effective connectivity of the seizure onset zone and the manner in which seizure activity spreads could lead to specifically-tailored therapies for epilepsy. We applied the electrical amygdala kindling model in two rhesus monkeys until these animals displayed consistent stage IV seizures. At this stage, we investigated the effective connectivity of the amygdala by means of electrical microstimulation during fMRI (EM-fMRI). In addition, we imaged changes in perfusion during a seizure using ictal SPECT perfusion imaging. The spatial overlap between the connectivity network and the ictal perfusion network was assessed both at the regional level, by calculating Dice coefficients using anatomically defined regions of interest, and at the voxel level. The kindled amygdala was extensively connected to bilateral cortical and subcortical structures, which in many cases were connected multisynaptically to the amygdala. At the regional level, the spatial extents of many of these fMRI activations and deactivations corresponded to the respective increases and decreases in perfusion imaged during a stage IV seizure. At the voxel level, however, some regions showed residual seizure-specific activity (not overlapping with the EM-fMRI activations) or fMRI-specific activation (not overlapping with the ictal SPECT activations), indicating that frequently, only a part of a region anatomically connected to the seizure onset zone participated in seizure propagation. Thus, EM-fMRI in the amygdala of electrically-kindled monkeys reveals widespread areas that are often connected multisynaptically to the seizure focus. Seizure activity appears to spread, to a large extent, via these connected areas.
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Van Dromme IC, Premereur E, Verhoef BE, Vanduffel W, Janssen P. Posterior Parietal Cortex Drives Inferotemporal Activations During Three-Dimensional Object Vision. PLoS Biol 2016; 14:e1002445. [PMID: 27082854 PMCID: PMC4833303 DOI: 10.1371/journal.pbio.1002445] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 03/18/2016] [Indexed: 11/18/2022] Open
Abstract
The primate visual system consists of a ventral stream, specialized for object recognition, and a dorsal visual stream, which is crucial for spatial vision and actions. However, little is known about the interactions and information flow between these two streams. We investigated these interactions within the network processing three-dimensional (3D) object information, comprising both the dorsal and ventral stream. Reversible inactivation of the macaque caudal intraparietal area (CIP) during functional magnetic resonance imaging (fMRI) reduced fMRI activations in posterior parietal cortex in the dorsal stream and, surprisingly, also in the inferotemporal cortex (ITC) in the ventral visual stream. Moreover, CIP inactivation caused a perceptual deficit in a depth-structure categorization task. CIP-microstimulation during fMRI further suggests that CIP projects via posterior parietal areas to the ITC in the ventral stream. To our knowledge, these results provide the first causal evidence for the flow of visual 3D information from the dorsal stream to the ventral stream, and identify CIP as a key area for depth-structure processing. Thus, combining reversible inactivation and electrical microstimulation during fMRI provides a detailed view of the functional interactions between the two visual processing streams.
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van Heukelum S, Kelderhuis J, Janssen P, van Luijtelaar G, Lüttjohann A. Timing of high-frequency cortical stimulation in a genetic absence model. Neuroscience 2016; 324:191-201. [PMID: 26964688 DOI: 10.1016/j.neuroscience.2016.02.070] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 02/27/2016] [Accepted: 02/29/2016] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Seizure control is one of the ultimate aims of epileptology: here acute and prolonged effects of closed loop high-frequency stimulation of the somatosensory cortex on the expression of spontaneously occurring spike-wave discharges (SWD) were investigated in a genetic absence model. Effects of closed loop stimulation in the experimental group were compared with a yoked control group allowing to investigate the effect of timing related to SWD occurrence, while controlling for amount and intensity of stimulation. METHODS WAG/Rij rats were implanted with stimulation electrodes in the deep layers of the somatosensory cortex, and recording electrodes in the cortex and thalamus. Closed-loop and yoked stimulation (1 sec trains, biphasic 0.4 msec pulses, 130 Hz) sessions lasted 24h. The stimulation sessions were preceded and followed by baseline and post stimulation 24-h recordings. RESULTS Closed-loop stimulation interrupted SWD and duration of SWD was shortened. Both types of stimulation resulted in a reduction in SWD number during stimulation sessions. Closed-loop stimulation also resulted in less SWD during the last eight hours of the post-stimulation recording session. Sometimes yoked stimulation induced low-frequency afterdischarges. DISCUSSION SWD can be aborted by closed-loop stimulation of the somatosensory cortex, and at the same time the number of SWD was reduced. It can be regarded as a relatively safe neuromodulatory technique without habituation. The reduction of SWD during yoked stimulation session might be caused by 3 Hz afterdischarges. The reduction of SWD on the stimulation and post-stimulation sessions demonstrates the critical relevance of timing for the induction of longer lasting neuromodulatory effects: it suggests that absence seizures themselves might be involved in their reoccurrence.
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