A dedicated insertion tool has been fabricated to achieve a precise insertion of the microprobes and their subsequent mechanical decoupling.
Due to the geometry and the mechanical stability of these microprobes, insertions are possible without the need for prior opening of the dura mater. Crosstalk between the channels is investigated, as well as the electrode stability for a time period of one month in vitro. The hybrid integration of a ribbon cable with high flexibility provides the connection of the electrodes to external instrumentation. Silicon microprobes with 36 electrodes arranged on four shafts are fabricated using MEMS technology. more This paper reports on a neural device for chronic implantation into the cerebral cortex. This paper reports on a neural device for chronic implantation into the cerebral cortex. In both areas, 3D-shape selective neurons were co-localized with neurons showing motor-related activity during object grasping in the dark, indicating a close convergence of visual and motor information on the same clusters of neurons. Furthermore, F5a neurons were more sensitive to small amplitudes of 3D curvature and could detect subtle differences in 3D structure more reliably than AIP neurons. In both areas neurons respond selectively to 3D shape defined by binocular disparity, but the latency of the neural selectivity is approximately 10 ms longer in F5a compared to AIP, consistent with its higher position in the hierarchy of cortical areas. The representation of three-dimensional (3D) shape has been studied in two interconnected areas known to be critical for object grasping: area AIP and area F5a in the ventral premotor cortex (PMv), to which AIP projects. These findings challenge the current understanding of area AIP as a critical stage in the dorsal stream for the extraction of object affordances. A number of studies have investigated the coding of 2D shape in the anterior intraparietal area (AIP), one of the end-stage areas of the dorsal stream which has been implicated in the extraction of affordances for the purpose of grasping. Recent research has demonstrated that object shape is also processed in the dorsal visual stream, which is specialized for spatial vision and the planning of actions.
more The primate visual system extracts object shape information for object recognition in the ventral visual stream. The primate visual system extracts object shape information for object recognition in the ventral. Our data indicate that the different mesial temporal lobe seizure types occur within a common network affecting several parts of the brain, and that seizure severity may be determined by seizure-induced epileptogenesis within a bihemispheric network that is implicated from the start of the process. A large portion of the ictal network was involved in the early stages of epileptogenesis and subsequently expanded over time as seizure severity evolved. Ictal SPECT perfusion imaging showed well-localized but widely distributed regions of hyperperfusion and hypoperfusion, in both cortical and subcortical structures, at every seizure stage. During this time, the animals progressed through four clinical stages ranging from interrupting ongoing behavior to bilateral convulsions. Afterdischarge duration increased slowly over 477 days for monkey K and 515 days for monkey S (18 ± 8 s in stage I 52 ± 13 s in stage IV). Ictal perfusion single photon emission computed tomography (SPECT) imaging was performed during each of the four predefined clinical stages. Two rhesus monkeys were electrically kindled through chronically implanted electrodes in the right amygdala over a period of 16 and 17 months.
In the macaque monkey, electrical amygdala kindling develops slowly and provides an opportunity for investigating ictal perfusion changes during epileptogenesis. more Amygdala kindling is a widely used animal model for studying mesial temporal lobe epileptogenesis. Amygdala kindling is a widely used animal model for studying mesial temporal lobe epileptogenesis.
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