TWISP: A Transgenic Worm for Interrogating Signal Propagation in C. elegans

Genetically encoded optical indicators and actuators of neural activity allow for all-optical investigations of signaling in the nervous system. But commonly used indicators, actuators and expression strategies are poorly suited for systematic measurements of signal propagation at brain scale and cellular resolution. Large scale measurements of the brain require indicators and actuators with compatible excitation spectra to avoid optical crosstalk. They must be highly expressed in every neuron but at the same time avoid lethality and permit the animal to reach adulthood. Their expression must also be compatible with additional fluorescent labels to locate and identify neurons, such as those in the NeuroPAL cell identification system. We present TWISP, a Transgenic Worm for Interrogating Signal Propagation, that addresses these needs and enables optical measurements of evoked calcium activity at brain scale and cellular resolution in the nervous system of the nematode Caenorhabditis elegans. We express in every neuron a non-conventional optical actuator, the gustatory receptor homolog GUR-3 + PRDX-2 under the control of a drug-inducible system QF + hGR, and calcium indicator GCAMP6 s, in a background with additional fluorophores of the NeuroPAL cell ID system. We show that this combination, but not others tested, avoids optical-crosstalk, creates strong expression in the adult, and generates stable transgenic lines for systematic measurements of signal propagation in the worm brain.

Fertility in seasonal-calving pasture-based lactating dairy cows following timed artificial insemination or timed embryo transfer with fresh or frozen in vitro-produced embryos

The objective was to compare pregnancy per service event (P/S) in lactating dairy cows following timed artificial insemination (AI) or timed embryo transfer (ET) using either fresh or frozen in vitro-produced embryos. Oocytes were collected once per week for up to 9 wk using transvaginal ovum pick-up from elite dairy donors (ET-DAIRY; n = 40; Holstein-Friesian and Jersey) and elite beef donors (ET-ELITE-BEEF; n = 21; Angus). Both ET-DAIRY and ET-ELITE-BEEF donors consisted of heifers and cows. In addition, oocytes were collected from the ovaries of beef heifers of known pedigree following slaughter at a commercial abattoir (ET-COMM-BEEF; n = 119). Following in vitro maturation and fertilization, presumptive zygotes were cultured in vitro to the blastocyst stage. Grade 1 blastocysts were either transferred fresh or frozen for on-farm thawing and direct transfer. A total of 1,106 recipient cows (all lactating, predominantly Holstein-Friesian) located on 16 herdlets were blocked based on parity, calving date, and Economic Breeding Index, and randomly assigned to receive AI (n = 243) or ET (n = 863) after estrous synchronization with a 10-d Progesterone-synch protocol. Cows assigned to ET were further randomized to receive fresh (n = 187) or frozen (n = 178) ET-ELITE-BEEF embryos, fresh (n = 169) or frozen (n = 162) ET-DAIRY embryos, or fresh (n = 80) or frozen (n = 87) ET-COMM-BEEF embryos. Pregnancy was diagnosed using transrectal ultrasound on d 32 to 35 after synchronized ovulation and confirmed on d 62 to 65, at which time fetal sex was determined. Pregnancy per service event at d 32 was not different between AI (48.8%) and ET (48.9%) and did not differ between dairy and beef embryos (50.3% vs. 48.1%, respectively). However, P/S was less on d 32 following transfer of frozen embryos (41.6%) compared with fresh embryos (56.1%). Pregnancy loss between d 32 and 62 was greater for ET (15.1%) compared with AI (4.7%), with greater losses observed for frozen beef (18.5%), fresh beef (17.3%), and frozen dairy (19.2%) compared with fresh dairy (6.0%) embryos. Serum progesterone (P4) concentration on d 7 was associated with P/S at d 32 and 62. Cows in the quartile with the least serum P4 concentrations (quartile 1) had less probability of being pregnant on d 32 (33.4%) compared with cows in the 3 upper quartiles for serum P4 (45.7%, 55.6%, and 61.2% for quartile 2, quartile 3, and quartile 4, respectively). Sex ratio (male:female) at d 62 was skewed toward more male fetuses following ET (61.1:38.9) compared with AI (43.2:56.8) and was consistent with the sex ratio among in vitro blastocysts (61.2:38.8). In conclusion, P/S was similar for AI and ET, although pregnancy loss between d 32 and 62 was greater for ET than for AI.

Light evokes stereotyped global brain dynamics in Caenorhabditis elegans

Stereotyped oscillations in population neural activity recordings from immobilized Caenorhabditis elegans have garnered interest for their striking low dimensionality and their evocative state-space trajectories or manifolds. Previously these oscillations have been interpreted as intrinsically driven global motor commands. Here we test whether these oscillations are intrinsic. We show that similar oscillations are evoked by high-intensity blue light commonly used for calcium imaging. Oscillations are reduced or absent and have a lower frequency when a longer imaging wavelength is used. Under the original blue light illumination, oscillations are reduced or have a lower frequency in animals that lack GUR-3, an endogenous light- and hydrogen-peroxide-sensitive gustatory receptor. Additional experiments with hydrogen peroxide are consistent with GUR-3's involvement. We therefore propose that blue light evokes global oscillations in part through the creation of reactive oxygen species that activate the hydrogen-peroxide-sensing receptor GUR-3.

Neural signal propagation atlas of Caenorhabditis elegans

Establishing how neural function emerges from network properties is a fundamental problem in neuroscience1. Here, to better understand the relationship between the structure and the function of a nervous system, we systematically measure signal propagation in 23,433 pairs of neurons across the head of the nematode Caenorhabditis elegans by direct optogenetic activation and simultaneous whole-brain calcium imaging. We measure the sign (excitatory or inhibitory), strength, temporal properties and causal direction of signal propagation between these neurons to create a functional atlas. We find that signal propagation differs from model predictions that are based on anatomy. Using mutants, we show that extrasynaptic signalling not visible from anatomy contributes to this difference. We identify many instances of dense-core-vesicle-dependent signalling, including on timescales of less than a second, that evoke acute calcium transients-often where no direct wired connection exists but where relevant neuropeptides and receptors are expressed. We propose that, in such cases, extrasynaptically released neuropeptides serve a similar function to that of classical neurotransmitters. Finally, our measured signal propagation atlas better predicts the neural dynamics of spontaneous activity than do models based on anatomy. We conclude that both synaptic and extrasynaptic signalling drive neural dynamics on short timescales, and that measurements of evoked signal propagation are crucial for interpreting neural function.

Comparison of three reproductive management strategies for lactating dairy cows using combination of estrus detection or ovulation synchronization and Fixed-Timed Artificial Insemination

The objective of this study was to compare the reproductive performance of lactating dairy cows submitted to first AI after combination of estrus detection and fixed timed AI (FTAI) and FTAI only. Cows were randomly assigned to receive AI at detected estrus between 50 and 70 d in milk (DIM), if not detected in estrus, were enrolled in either Ovsynch (ED-Ov, n = 485) or PRIDsynch (ED-PR, n = 505) protocols; or received FTAI at 80 DIM after Double-Ovsynch protocol (DO, n = 501). Cows were body condition scored (BCS) at calving and at 43 DIM; and evaluated for postpartum disorders within 7 d postpartum; clinical mastitis, lameness and bovine respiratory disease were recorded until first AI. Ovarian cyclicity was monitored at 43 and 50 DIM, and at 70 and 77 DIM. Pregnancy diagnoses (PD) were performed at 32 and 63 d after AI. Overall prevalence of postpartum anovulation was 7.8%. Pregnancy per AI (P/AI) did not differ between reproductive strategies at 32 d PD (ED-Ov = 43.2%; ED-PR = 41.7%; DO= 45.3%). Primiparous cows had greater P/AI than multiparous cows (53.7% vs 36.8%). Cows on farm 1 had lower P/AI compared with their counterparts on farm 2 (42.1% vs 45.4%). Cows with BCS > 2.5 at 43 DIM had greater P/AI compared with cows with BCS ≤ 2.5 (44.5% vs 34.7%). Similar P/AI for cow's receiving AI at detected estrus and FTAI, low prevalence of disease anovulation may have contributed to the similar performance of ED-Ov, ED-PR and DO.

Effect of delayed timing of artificial insemination with sex-sorted semen on pregnancy per artificial insemination in synchronized dairy heifers managed in a seasonal-calving pasture-based system

The objective of this study was to evaluate the timing of artificial insemination (AI) with frozen-thawed sex-sorted semen on pregnancy per AI (P/AI) in dairy heifers. A 6-d progesterone Co-Synch protocol was used for ovulation synchronization of dairy heifers, with timed AI (TAI) coincident with (TAI-0) or 8 h (TAI-8) after the second injection of GnRH, corresponding to either 48 h or 56 h after removal of the progesterone-releasing intravaginal device. Pregnancy diagnosis was conducted by transrectal ultrasound scanning of the uterus 34 d after TAI (n = 816 records available for analysis). Generalized linear mixed models were used to examine the effects of treatment on P/AI. Treatment (n = 2), herd (n = 11), and treatment × herd were included as categorical fixed effects. Heifer body weight and Economic Breeding Index values for milk production, fertility, calving performance, beef carcass, cow maintenance, cow management, and health were included as continuous fixed effects. Heifer ID was included as a random effect. Pregnancy per AI was greater for TAI-8 heifers (59%) compared with TAI-0 heifers (50%). Pregnancy per AI ranged from 38% to 75% between herds but there was no treatment × herd interaction. The fertility subindex (positive) and the cow management subindex (negative) were the only continuous animal variables associated with P/AI. Delaying the timing of AI with frozen-thawed sex-sorted semen by 8 h in dairy heifers enrolled on a 6-d progesterone Co-Synch protocol improved P/AI.

TWISP: A Transgenic Worm for Interrogating Signal Propagation in C. elegans

Genetically encoded optical indicators and actuators of neural activity allow for all-optical investigations of signaling in the nervous system. But commonly used indicators, actuators and expression strategies are poorly suited for systematic measurements of signal propagation at brain scale and cellular resolution. Large scale measurements of the brain require indicators and actuators with compatible excitation spectra to avoid optical crosstalk. They must be highly expressed in every neuron but at the same time avoid lethality and permit the animal to reach adulthood. And finally, their expression must be compatible with additional fluorescent labels to locate and identify neurons, such as those in the NeuroPAL cell identification system. We present TWISP, a Transgenic Worm for Interrogating Signal Propagation, that address these needs and enables optical measurements of evoked calcium activity at brain scale and cellular resolution in the nervous system of the nematode Caenorhabditis elegans. We express in every neuron a non-conventional optical actuator, the gustatory receptor homolog GUR-3+PRDX-2 under the control of a drug-inducible system QF+hGR, and calcium indicator GCAMP6s, in a background with additional fluorophores of the NeuroPAL cell ID system. We show that this combination, but not others tested, avoids optical-crosstalk, creates strong expression in the adult, and generates stable transgenic lines for systematic measurements of signal propagation in the worm brain.

Effect of a progesterone-releasing intravaginal device (PRID) for 8 days during a modified Ovsynch protocol on pregnancy outcomes in lactating Holstein cows

Our objective was to evaluate the effect of a progesterone-releasing intravaginal device (PRID) in a 7-d Ovsynch protocol on pregnancy per artificial insemination (P/AI) and pregnancy loss, compared with a standard 7-d Ovsynch protocol without progesterone supplementation. We hypothesized that progesterone supplementation during an Ovsynch protocol would increase P/AI and decrease pregnancy loss. Data were collected on lactating Holstein cows (n = 716) that either received a 7-d Ovsynch protocol (control: d 0, 100 µg of GnRH; d 7, 500 µg of cloprostenol; d 9, µg of GnRH; n = 360) or a modified Ovsynch protocol with addition of a PRID (PRIDsynch; d 0, 100 µg of GnRH + PRID; d 7, 25 mg of dinoprost; d 8, PRID removal; d 9, 100 µg of GnRH; n = 356). All cows received timed artificial insemination (TAI) approximately 16 h after the second GnRH treatment. Pregnancy diagnosis was performed via ultrasonography on d 38 ± 3 after TAI and rechecked on d 80 ± 7 after TAI. Reproductive performance differed between treatments, with PRIDsynch cows having greater (38.9%) P/AI compared with control cows (31.7%) at d 38 ± 3 and also at d 80 ± 7 (34.6% vs. 28.9%, for PRIDsynch and control cows, respectively). Pregnancy loss did not differ among treatments.

Decoding locomotion from population neural activity in moving C. elegans

We investigated the neural representation of locomotion in the nematode C. elegans by recording population calcium activity during movement. We report that population activity more accurately decodes locomotion than any single neuron. Relevant signals are distributed across neurons with diverse tunings to locomotion. Two largely distinct subpopulations are informative for decoding velocity and curvature, and different neurons’ activities contribute features relevant for different aspects of a behavior or different instances of a behavioral motif. To validate our measurements, we labeled neurons AVAL and AVAR and found that their activity exhibited expected transients during backward locomotion. Finally, we compared population activity during movement and immobilization. Immobilization alters the correlation structure of neural activity and its dynamics. Some neurons positively correlated with AVA during movement become negatively correlated during immobilization and vice versa. This work provides needed experimental measurements that inform and constrain ongoing efforts to understand population dynamics underlying locomotion in C. elegans.

Fast deep neural correspondence for tracking and identifying neurons in C. elegans using semi-synthetic training

We present an automated method to track and identify neurons in C. elegans, called 'fast Deep Neural Correspondence' or fDNC, based on the transformer network architecture. The model is trained once on empirically derived semi-synthetic data and then predicts neural correspondence across held-out real animals. The same pre-trained model both tracks neurons across time and identifies corresponding neurons across individuals. Performance is evaluated against hand-annotated datasets, including NeuroPAL (Yemini et al., 2021). Using only position information, the method achieves 79.1% accuracy at tracking neurons within an individual and 64.1% accuracy at identifying neurons across individuals. Accuracy at identifying neurons across individuals is even higher (78.2%) when the model is applied to a dataset published by another group (Chaudhary et al., 2021). Accuracy reaches 74.7% on our dataset when using color information from NeuroPAL. Unlike previous methods, fDNC does not require straightening or transforming the animal into a canonical coordinate system. The method is fast and predicts correspondence in 10 ms making it suitable for future real-time applications.

Nonequilibrium Green's Functions for Functional Connectivity in the Brain

A theoretical framework describing the set of interactions between neurons in the brain, or functional connectivity, should include dynamical functions representing the propagation of signal from one neuron to another. Green's functions and response functions are natural candidates for this but, while they are conceptually very useful, they are usually defined only for linear time-translationally invariant systems. The brain, instead, behaves nonlinearly and in a time-dependent way. Here, we use nonequilibrium Green's functions to describe the time-dependent functional connectivity of a continuous-variable network of neurons. We show how the connectivity is related to the measurable response functions, and provide two illustrative examples via numerical calculations, inspired from Caenorhabditis elegans.

Measuring and modeling whole-brain neural dynamics in Caenorhabditis elegans

The compact nervous system of the nematode Caenorhabditis elegans makes it a powerful playground to study how neural dynamics constrained by neuroanatomy generate neural function and behavior. The ability to record neural activity from the whole brain simultaneously in this worm has opened several research avenues and is providing insights into brain-wide neural coding of locomotion, sleep, and other behaviors. We review these findings and the development of new methods, including new microscopes, new genetic tools, and new modeling approaches. We conclude with a discussion of the role of theory in interpreting or driving new experiments in C. elegans and potential paths forward.

Evaluation of delayed timing of artificial insemination with sex-sorted sperm on pregnancy per artificial insemination in seasonal-calving, pasture-based lactating dairy cows

The objective was to use ovulation synchronization with timed artificial insemination (TAI) to evaluate the effect of timing of artificial insemination (AI) with frozen sex-sorted sperm on fertility performance in pasture-based compact calving herds. Ejaculates from 3 Holstein-Friesian bulls were split and processed to provide frozen sex-sorted sperm (SS) at 4 × 10⁶ sperm per straw, and frozen conventional sperm at 15 × 10⁶ sperm per straw (CONV). A modified Progesterone-Ovsynch protocol was used for estrous synchronization, with TAI occurring 16 h after the second GnRH injection for cows assigned to CONV, and either 16 h (SS-16) or 22 h (SS-22) for cows assigned to SS. Pregnancy diagnosis was conducted by transrectal ultrasound scanning of the uterus 35 to 40 d after TAI (n = 2,175 records available for analysis). Generalized linear mixed models were used to examine the effects of treatment on pregnancy per artificial insemination (P/AI). Fixed effects included treatment (n = 3), bull (n = 3), treatment by bull interaction, parity (n = 4), days-in-milk category (n = 3), and treatment by days-in-milk category, with herd (n = 24) included as a random effect. Pregnancy per AI was greater for CONV compared with both SS-16 and SS-22 (61.1%, 49.0%, and 51.3%, respectively), and the SS treatments did not differ from each other (relative P/AI for SS-16 and SS-22 vs. CONV were 80.2% and 84.0%, respectively). There were significant bull and treatment by bull interaction effects. Additional analysis was undertaken using a model that included herd as a fixed effect. This analysis identified marked herd-to-herd variation (within-herd relative P/AI for the combined SS treatments vs. CONV ranged from 48-121%). The tertile of herds with the best performance achieved a mean relative P/AI of 100% (range = 91-121%), indicating that P/AI equivalent to CONV is achievable with SS. Conversely, the tertile of herds with the poorest performance achieved a mean relative P/AI of 67% (range = 48-77%). We found that SS resulted in poorer overall P/AI compared with CONV sperm regardless of timing of AI. Marked variation existed between herds; however, one-third of herds achieved P/AI results equal to CONV. Identification of factors responsible for the large herd-to-herd variation in P/AI with SS, and development of strategies to reduce this variation, warrant further research.

Searching for collective behavior in a small brain

In large neuronal networks, it is believed that functions emerge through the collective behavior of many interconnected neurons. Recently, the development of experimental techniques that allow simultaneous recording of calcium concentration from a large fraction of all neurons in Caenorhabditis elegans-a nematode with 302 neurons-creates the opportunity to ask whether such emergence is universal, reaching down to even the smallest brains. Here, we measure the activity of 50+ neurons in C. elegans, and analyze the data by building the maximum entropy model that matches the mean activity and pairwise correlations among these neurons. To capture the graded nature of the cells' responses, we assign each cell multiple states. These models, which are equivalent to a family of Potts glasses, successfully predict higher statistical structure in the network. In addition, these models exhibit signatures of collective behavior: the state of single cells can be predicted from the state of the rest of the network; the network, despite being sparse in a way similar to the structural connectome, distributes its response globally when locally perturbed; the distribution over network states has multiple local maxima, as in models of memory; and the parameters that describe the real network are close to a critical surface in this family of models.

Signatures of Enhanced Superconducting Phase Coherence in Optimally Doped Bi_{2}Sr_{2}Y_{0.08}Ca_{0.92}Cu_{2}O_{8+δ} Driven by Midinfrared Pulse Excitations

Optimally doped cuprate are characterized by the presence of superconducting fluctuations in a relatively large temperature region above the critical transition temperature. We reveal here that the effect of thermal disorder, which decreases the condensate phase coherence at equilibrium, can be dynamically contrasted by photoexcitation with ultrashort midinfrared pulses. In particular, our findings reveal that light pulses with photon energy comparable to the amplitude of the superconducting gap and polarized in plane along the copper-copper direction can dynamically enhance the optical response associated with the onset of superconductivity. We propose that this effect can be rationalized by an effective d-wave BCS model, which reveals that midinfrared pulses result in a transient increase of the phase coherence.

Probing the Fluctuations of Optical Properties in Time-Resolved Spectroscopy

We show that, in optical pump-probe experiments on bulk samples, the statistical distribution of the intensity of ultrashort light pulses after interaction with a nonequilibrium complex material can be used to measure the time-dependent noise of the current in the system. We illustrate the general arguments for a photoexcited Peierls material. The transient noise spectroscopy allows us to measure to what extent electronic degrees of freedom dynamically obey the fluctuation-dissipation theorem, and how well they thermalize during the coherent lattice vibrations. The proposed statistical measurement developed here provides a new general framework to retrieve dynamical information on the excited distributions in nonequilibrium experiments, which could be extended to other degrees of freedom of magnetic or vibrational origin.

Effect of combined exogenous progesterone with luteotrophic support via equine chorionic gonadotrophin (eCG) on corpus luteum development, circulating progesterone concentrations and embryo development in cattle

The aim was to examine the effect of a single intramuscular (i.m.) injection of equine chorionic gonadotrophin (eCG) on Day 3 after oestrus on corpus luteum (CL) development, circulating progesterone and conceptus development in cross-bred beef heifers. In Experiment 1, heifers received: (1) saline, or a single i.m. injection of eCG on Day 3 at (2) 250 IU (3) 500 IU (4) 750 IU or (5) 1000 IU. Administration of eCG resulted in increased luteal tissue area and progesterone and oestradiol concentrations compared with controls. In Experiment 2, heifers received (1) a progesterone-releasing intravaginal device (PRID Delta) from Day 3 to 5 or (2) a PRID Delta from Day 3 to 5 plus a single injection of 750 IU eCG on Day 3. In vitro-produced blastocysts (n = 10 per recipient) were transferred on Day 7 and heifers were slaughtered on Day 14 to assess conceptus development. Administration of eCG reduced the number of short cycles (6.3% vs 31.3%) and increased mean luteal tissue weight (P = 0.02). Insertion of a PRID Delta on Day 3 resulted in an elevation (P < 0.05) in serum progesterone until removal on Day 5. Administration of eCG at the time of PRID Delta insertion resulted in higher progesterone levels (P < 0.05) from Day 10 onwards. Conceptus dimensions were not affected. In conclusion, a single injection of eCG on Day 3 increased CL size and progesterone concentrations and, when given in conjunction with a progesterone-releasing device, appeared to reduce the number of short cycles, presumably due to its luteotrophic nature. The implications of the elevated oestradiol concentrations for embryo quality require further study.

100 EMBRYO SURVIVAL AND CONCEPTUS ELONGATION FOLLOWING ASYNCHRONOUS EMBRYO TRANSFER IN CATTLE

Maternal progesterone (P4) regulates early conceptus growth and development in ruminants. Early embryo transfer studies in sheep and cattle demonstrated a need for close synchrony between the embryo and the uterine environment of the recipient. However, manipulating P4 may be one way of strategically regulating the temporal changes that normally occur in the uterine environment in order to allow flexibility in the timing of embryo transfer. For example, previous studies have demonstrated that P4 administration during the first few days of the oestrous cycle facilitates pregnancy establishment with older embryos. The aim of this study was to examine the effect of embryo-uterine synchrony on conceptus elongation in cattle. Oestrous cycles of crossbred beef heifers were synchronised using an 8-day P4-Releasing Intravaginal Device (PRID Delta®, CEVA, Mountain View, CA, USA) with administration of a prostaglandin F2α analogue (Enzaprost®, CEVA; 5 mL equivalent to 25 mg of dinoprost) given on the day before PRID removal. Heifers were checked for signs of oestrus 4 times per day commencing 30 h after PRID withdrawal. Only those seen in standing oestrus (n = 50) were randomly assigned to 1 of 5 treatment groups to receive Day 7 in vitro-produced blastocysts (n = 10 per recipient) (1) on Day 5 post-oestrus; (2) on Day 5, with P4 supplementation via PRID from Day 3 to 5 + 750 IU of eCG at PRID insertion; (3) on Day 5, PRID Delta from Day 3 to 5 plus 3000 IU of hCG at PRID insertion; (4) on Day 7, or (5) on Day 9. At embryo age Day 14, all heifers were slaughtered and the uterus was flushed to recover and measure conceptuses. Data are summarised in Table 1. Fewer recipients yielded conceptuses (P < 0.05) and fewer conceptuses overall were recovered (P < 0.05) following transfer on Day 5 compared with Day 7 or Day 9. Supplementation with P4 resulted in short cycles (evidenced by corpus luteum regression and/or a recent ovulation at slaughter) in 33.3 to 54.5% of recipients receiving embryos on Day 5. Mean conceptus length was greater (P < 0.05) following transfer to an advanced uterus. In conclusion, transfer of embryos to a retarded (Day 5) uterine environment results in poor embryo survival. Supplementation with P4 shortened the interoestrous period in a significant number of heifers. Transfer to an advanced uterine environment promotes conceptus elongation, presumably driven by P4. Table 1.Embryo survival and conceptus length data

EEG patterns and epileptic seizures in acute phase stroke

BACKGROUND

The rate of early post-stroke epileptic seizures ranges from 2 to 33%. This wide range is likely due to differences in study design, patient selection and type of neurophysiological monitoring. Electroencephalography (EEG), which is not used in the routine work-up of acute stroke, is the best neurodiagnostic technique for detecting epileptic activity, especially in patients with non-convulsive post-stroke epileptic activity. The aim of this study was to analyze patterns on EEGs performed within 24 h of stroke onset, and to investigate correlations between these patterns and the occurrence of early epileptic seizures and status epilepticus (SE), vascular risk factors, stroke subtypes and short-term outcome.

METHODS

We prospectively studied 232 patients (mean age 71 ± 12 years; 177 ischemic strokes and 55 hemorrhagic). EEG recording was performed within 24 h from hospitalization. The follow-up lasted 1 week.

RESULTS

Fifteen patients (6.5%) had early seizures within 24 h; 10 of these patients had focal SE with or without secondary generalization. EEG revealed sporadic epileptiform focal abnormalities in 10% and periodic lateralized epileptiform discharges (PLEDs) in 6%. SE was recorded in 71.4% of patients with PLEDs. At the multivariate analysis, only early epileptic manifestations (p < 0.001) were independently associated with PLEDs.

CONCLUSIONS

Our study confirms that seizures are not frequent in the early phase of acute stroke and occur prevalently as focal SE at onset. EEG may help to detect specific patterns, such as PLEDs, that are closely related to early seizures. EEG monitoring should be performed in order to detect purely electrographic seizures.

Transcranial Doppler for brain death in infants: the role of the fontanelles

OBJECTIVE

Transcranial Doppler (TCD) is a sensitive technique for circulatory arrest diagnosis in brain death when patterns such as reverberant flow and short systolic spikes are observed. In infants, the nonossified fontanelles compensate for intracranial hypertension. We describe TCD patterns in infants with brain death, different from adults, with the hemodynamic modifications induced by anterior fontanelle compression.

METHOD

TCD was performed in 2 infants with diagnosed brain death admitted to the neonatal intensive care unit.

RESULTS

TCD showed a large peak 'reverberant' flow, with a high peak systolic velocity and a consistent retrograde component, away from the brain. Compression of the anterior fontanelle induced, at first, a reduction in systolic flow with the subsequent appearance of the characteristic short systolic spikes. Upon compression removal, a brief increase in the systolic flow was observed before the prompt reappearance of the reverberant flow.

CONCLUSION

TCD for brain death diagnosis should be done cautiously in infants. In these cases, reverberating flow may be indicative of circulatory arrest even if with a large peak and with a high peak systolic velocity. Heavy fontanelle compression may reproduce the classical adult TCD patterns of brain death, thus supporting the diagnosis of cerebral circulatory arrest.