Growing evidence suggests that distributed spatial attention may invoke theta (3–9 Hz) rhythmic sampling processes. The neuronal basis of such attentional sampling is, however, not fully understood. ...Here we show using array recordings in visual cortical area V4 of two awake macaques that presenting separate visual stimuli to the excitatory center and suppressive surround of neuronal receptive fields (RFs) elicits rhythmic multi-unit activity (MUA) at 3–6 Hz. This neuronal rhythm did not depend on small fixational eye movements. In the context of a distributed spatial attention task, during which the monkeys detected a spatially and temporally uncertain target, reaction times (RTs) exhibited similar rhythmic fluctuations. RTs were fast or slow depending on the target occurrence during high or low MUA, resulting in rhythmic MUA-RT cross-correlations at theta frequencies. These findings show that theta rhythmic neuronal activity can arise from competitive RF interactions and that this rhythm may result in rhythmic RTs potentially subserving attentional sampling.
•Receptive field interactions induce theta rhythmic activation in visual cortex•The neuronal rhythm does not depend on small fixational eye movements•Reaction time fluctuations lock to the neuronal rhythm under distributed attention
Kienitz et al. show that receptive field interactions induce theta rhythmic neuronal activity in visual area V4 that is independent of eye movements. Under distributed attention, periodic reaction times were locked to the neuronal rhythm. Rhythmic modulation of neuronal sensitivity could thus explain attentional dynamics during visual competition.
When the SARS-CoV-2 pandemic reached Europe in 2020, a German governmental order forced clinics to immediately suspend elective care, causing a problem for patients with chronic illnesses such as ...epilepsy. Here, we report the experience of one clinic that converted its outpatient care from personal appointments to telemedicine services.
Documentations of telephone contacts and telemedicine consultations at the Epilepsy Center Frankfurt Rhine-Main were recorded in detail between March and May 2020 and analyzed for acceptance, feasibility, and satisfaction of the conversion from personal to telemedicine appointments from both patients' and medical professionals' perspectives.
Telephone contacts for 272 patients (mean age: 38.7 years, range: 17–79 years, 55.5% female) were analyzed. Patient-rated medical needs were either very urgent (6.6%, n = 18), urgent (23.5%, n = 64), less urgent (29.8%, n = 81), or nonurgent (39.3%, n = 107). Outpatient service cancelations resulted in a lack of understanding (9.6%, n = 26) or anger and aggression (2.9%, n = 8) in a minority of patients, while 88.6% (n = 241) reacted with understanding, or relief (3.3%, n = 9). Telemedicine consultations rather than a postponed face-to-face visit were requested by 109 patients (40.1%), and these requests were significantly associated with subjective threat by SARS-CoV-2 (p = 0.004), urgent or very urgent medical needs (p = 0.004), and female gender (p = 0.024). Telemedicine satisfaction by patients and physicians was high. Overall, 9.2% (n = 10) of patients reported general supply problems due to SARS-CoV-2, and 28.4% (n = 31) reported epilepsy-specific problems, most frequently related to prescriptions, or supply problems for antiseizure drugs (ASDs; 22.9%, n = 25).
Understanding and acceptance of elective ambulatory visit cancelations and the conversion to telemedicine consultations was high during the coronavirus disease 2019 (COVID-19) lockdown. Patients who engaged in telemedicine consultations were highly satisfied, supporting the feasibility and potential of telemedicine during the COVID-19 pandemic and beyond.
•Health care systems worldwide had to face reorganization during SARS-CoV-2 pandemic•Acceptance of the SARS-CoV-2-related conversion to telemedicine services was high•Urgent concerns, perception of SARS-CoV-2-associated threats, and female gender were associated with use of telemedicine•Patient and physician satisfaction with telemedicine services was high•Supply problems severely affected epilepsy patients during the SARS-CoV-2 pandemic
Abstract
Introduction
Delta power is a clinically established biomarker for abnormal brain processes. However, in patients with unilateral focal epilepsy (FE) it is still not well understood, how it ...relates to the epileptogenic zone and to neurocognitive functioning. The aim of the present study was thus to assess how delta power relates to the affected hemisphere, whether lateralization strength differs between the patients, and how changes in delta power correlate with cognitive functioning.
Method
We retrospectively studied patients with left (LFE) and right FE (RFE) who had undergone a resting‐state magnetoencephalography measurement. We computed global and hemispheric delta power and lateralization indices and examined whether delta power correlates with semantic and letter verbal fluency (former being a marker for language and verbal memory, latter for executive functions) in 26 FE patients (15 LFE, 11 RFE) and 10 healthy controls.
Results
Delta power was increased in FE patients compared to healthy controls. However, the increase across hemispheres was related to the site of the epileptic focus: On group level, LFE patients showed higher delta power in both hemispheres, whereas RFE patients primarily exhibited higher delta power in the ipsilateral right hemisphere. Both groups showed co‐fluctuations of delta power between the hemispheres. Besides, delta power correlated negatively only with letter verbal fluency.
Conclusion
The findings confirm and provide further evidence that delta power is a marker of pathological activity and abnormal brain processes in FE. Delta power dynamics differ between patient groups, indicating that delta power could offer additional diagnostic value. The negative association of delta power and letter verbal fluency suggests that executive dysfunctions are related to low frequency abnormalities.
Recent research indicates that attentional stimulus selection could be a rhythmic process. In monkey, neurons in V4 and IT exhibit rhythmic spiking activity in the theta range in response to a ...stimulus. When two stimuli are presented together, the rhythmic neuronal responses to each occur in anti-phase, a result indicative of competitive interactions. In addition, it was recently demonstrated that these alternating oscillations in monkey V4 modulate the speed of saccadic responses to a target flashed on one of the two competing stimuli. Here, we replicate a similar behavioral task in humans (7 participants, each performed 4000 trials) and report a pattern of results consistent with the monkey findings: saccadic response times fluctuate in the theta range (6 Hz), with opposite phase for targets flashed on distinct competing stimuli.
Sampling of information is thought to be an important aspect of explorative behaviour. Evidence for it has been gained in behavioural assessments of a variety of overt and covert cognitive domains, ...including sensation, attention, memory, eye movements and dexterity. A common aspect across many findings is that sampling tends to exhibit a rhythmicity at low frequencies (theta, 4–8 Hz; alpha, 9–12 Hz). Neurophysiological investigations in a wide range of species, including rodents, non‐human primates and humans have demonstrated the presence of sampling related neural oscillations in a number of brain areas ranging from early sensory cortex, hippocampus to high‐level cognitive areas. However, to assess whether rhythmic sampling represents a general aspect of exploratory behaviour one must critically evaluate the task parameters, and their potential link with neural oscillations. Here we focus on sampling during attentive vision to present an overview on the experimental conditions that are used to investigate rhythmic sampling and associated oscillatory brain activity in this domain. This review aims to (1) provide guidelines to efficiently quantify behavioural rhythms, (2) compare results from human and non‐human primate studies and (3) argue that the underlying neural mechanisms of sampling can co‐occur in both sensory and high‐level areas.
Rhythmic sampling of information is thought to be an important aspect of explorative behaviour. This review presents an overview on experimental conditions that are used to study rhythmic sampling and associated oscillatory brain activity during attentive vision. It provides guidelines to efficiently quantify behavioural rhythms, compares results from human and non‐human primate studies and argues that the underlying neural mechanisms of sampling can co‐occur in both sensory and high‐level areas.
Neuronal activity in visual area V4 is well known to be modulated by selective attention, and there are reports on V4 lesions leading to attentional deficits. However, it remains unclear whether V4 ...microstimulation can elicit attentional benefits. To test this hypothesis, we performed local microstimulation in area V4 and explored its spatial and time dynamics in two macaque monkeys performing a visual detection task. Microstimulation was delivered via chronically implanted multi-electrode arrays. We found that microstimulation increases average performance by 35% and reduces luminance detection thresholds by −30%. This benefit critically depends on the onset of microstimulation relative to the stimulus, consistent with known dynamics of endogenous attention. These results show that local microstimulation of V4 can improve behavior and highlight the critical role of V4 for attention.
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•Microstimulation of visual area V4 improves visual stimulus detection•Effects of V4 microstimulation extend to the other hemifield•Microstimulation effects are time dependent and consistent with attention dynamics
Kienitz et al. report that microstimulation of visual area V4 improves visual stimulus detection in macaque monkeys. This faciliatory effect extends to the other hemifield and is time dependent, consistent with dynamics of endogenous attention. These results highlight the critical role of V4 for visual processing and attention.
•Withdrawal of valproate (VPA) increases the alpha peak frequency (APF) in patients with epilepsy who have a normal baseline posterior dominant frequency.•APF correlates inversely with the daily dose ...of VPA in the absence of overt clinical or electroencephalographic signs of encephalopathy.•No significant change in APF occurs in patients withdrawn from levetiracetam (LEV).
Studies of the effect of valproate (VPA) on the background EEG have shown varying results. Therefore, we compared the effect of VPA and levetiracetam (LEV) on the EEG alpha peak frequency (APF).
We retrospectively examined the APF in resting-state EEG of patients undergoing inpatient video-EEG monitoring (VEM) during withdrawal of VPA or LEV. We assessed APF trends by computing linear fits across individual patients’ APF as a function of consecutive days, and correlated the APF and daily antiseizure medication (ASM) doses on a single-patient and group level.
The APF in the VPA-group significantly increased over days with falling VPA doses (p = 0.005, n = 13), but did not change significantly in the LEV-group (p = 0.47, n = 18). APF correlated negatively with daily ASM doses in the VPA-group (average of r = −0.74 ± 0.12 across patients, p = 0.0039), but not in the LEV-group (average of r = −0.17 ± 0.18 across patients, p = 0.4072).
Our results suggest that VPA treatment slows the APF. This APF reduction correlates with the daily dose of VPA and is not present in LEV treatment.
Our study identifies a VPA-related slowing of the APF even in patients without electroencephalographic or overt clinical signs of encephalopathy.
Status epilepticus (SE) is an acute, life-threatening medical condition that requires immediate, effective therapy. Therefore, the acute care of prolonged seizures and SE is a constant challenge for ...healthcare professionals, in both the pre-hospital and the in-hospital settings. Benzodiazepines (BZDs) are the first-line treatment for SE worldwide due to their efficacy, tolerability, and rapid onset of action. Although all BZDs act as allosteric modulators at the inhibitory gamma-aminobutyric acid (GABA)
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receptor, the individual agents have different efficacy profiles and pharmacokinetic and pharmacodynamic properties, some of which differ significantly. The conventional BZDs clonazepam, diazepam, lorazepam and midazolam differ mainly in their durations of action and available routes of administration. In addition to the common intravenous, intramuscular and rectal administrations that have long been established in the acute treatment of SE, other administration routes for BZDs—such as intranasal administration—have been developed in recent years, with some preparations already commercially available. Most recently, the intrapulmonary administration of BZDs via an inhaler has been investigated. This narrative review provides an overview of the current knowledge on the efficacy and tolerability of different BZDs, with a focus on different routes of administration and therapeutic specificities for different patient groups, and offers an outlook on potential future drug developments for the treatment of prolonged seizures and SE.
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