Withdrawal seizures vs on-medication seizures:an intracranial EEG recording case report

Background It has long been an interesting question of whether withdrawal seizures in epileptic patients differ from habitual seizures in terms of semiology and electrophysiology.Case presentation Here,we addressed this issue in a 40 year-old woman with drug-resistant focal epilepsy monitored by presurgical intracranial EEG.As a part of this routine pre-operative investigation,anti-seizure medications(ASMs)were halted;as a result,multiple withdrawal seizures were recorded before ASM readministration.During 4 days of invasive monitoring,we noticed three different phases in seizure organization:Acute withdrawal seizure(AWS):The first recorded seizure 10h after the implantation;the stabilized withdrawal seizures(SWS):seven habitual seizures recorded from 24h post implantation to readministration of ASMs;and the Non-withdrawal seizures(NWS):ten seizures recorded 24h after readministration of ASMs.AWS and SWS had the same semiology and same epileptic network,but the propagation time from the temporal pole to the para-hippocampal gyrus(PHG)and hippocampus ranged from no latency in AWS to up to 50 s in SWS.NWS were electrographic seizures,without any apparent clinical manifestation.Seizure onset in this type of seizure,as in the first two types,was in the temporal pole.However,NWS could last up to 3 min without involving the PHG or hippocampus.Conclusions We concluded that in acute withdrawal seizures the propagation time of epileptic activity is significantly reduced without affecting ictal organization network or semiology.Furthermore,ASM in this case had a remarkable influence on propagation rather than initiation of epileptic activity.

Local field potentials,spiking activity,and receptive fields in human visual cortex

The concept of receptive field(RF) is central to sensory neuroscience. Neuronal RF properties have been substantially studied in animals,while those in humans remain nearly unexplored. Here, we measured neuronal RFs with intracranial local field potentials(LFPs) and spiking activity in human visual cortex(V1/V2/V3). We recorded LFPs via macro-contacts and discovered that RF sizes estimated from lowfrequency activity(LFA, 0.5–30 Hz) were larger than those estimated from low-gamma activity(LGA, 30–60 Hz) and high-gamma activity(HGA, 60–150 Hz). We then took a rare opportunity to record LFPs and spiking activity via microwires in V1 simultaneously. We found that RF sizes and temporal profiles measured from LGA and HGA closely matched those from spiking activity. In sum, this study reveals that spiking activity of neurons in human visual cortex could be well approximated by LGA and HGA in RF estimation and temporal profile measurement, implying the pivotal functions of LGA and HGA in early visual information processing.

Face-Specific Activity in the Ventral Stream Visual Cortex Linked to Conscious Face Perception

When presented with visual stimuli of face images,the ventral stream visual cortex of the human brain exhibits face-specific activity that is modulated by the physical properties of the input images.However,it is still unclear whether this activity relates to conscious face perception.We explored this issue by using the human intracranial electroencephalography technique.Our results showed that face-specific activity in the ventral stream visual cortex was significantly higher when the subjects subjectively saw faces than when they did not,even when face stimuli were presented in both conditions.In addition,the face-specific neural activity exhibited a more reliable neural response and increased posterior-anterior direction information transfer in the“seen”condition than the“unseen”condition.Furthermore,the face-specific neural activity was significantly correlated with performance.These findings support the view that face-specific activity in the ventral stream visual cortex is linked to conscious face perception.