bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neural correlates of memory retrieval in the prefrontal cortex
Authors: Nácher Verónica , Ojeda Sabiela , Cadarso‐Suárez Carmen , Roca‐Pardiñas Javier , Acuña Carlos 
Published: August 2006

AbstractWorking memory includes short‐term representations of information that were recently experienced or retrieved from long‐term representations of sensory stimuli. Evidence is presented here that working memory activates the same dorsolateral prefrontal cortex neurons that: (a) maintained recently perceived visual stimuli; and (b) retrieved visual stimuli from long‐term memory (LTM). Single neuron activity was recorded in the dorsolateral prefrontal cortex while trained monkeys discriminated between two orientated lines shown sequentially, separated by a fixed interstimulus interval. This visual task required the monkey to compare the orientation of the second line with the memory trace of the first and to decide the relative orientation of the second. When the behavioural task required the monkey to maintain in working memory a first stimulus that continually changed from trial to trial, the discharge in these cells was related to the parameters − the orientation − of the memorized item. Then, what the monkey had to recall from memory was manipulated by switching to another task in which the first stimulus was not shown, and had to be retrieved from LTM. The discharge rates of the same neurons also varied depending on the parameters of the memorized stimuli, and their response was progressively delayed as the monkey performed the task. These results suggest that working memory activates dorsolateral prefrontal cortex neurons that maintain parametrical visual information in short‐term and LTM, and that the contents of working memory cannot be limited to what has recently happened in the sensory environment.
A thalamo‐cortico‐amygdala pathway mediates auditory fear conditioning in the intact brain
Authors: Boatman Jeffrey A. , Kim Jeansok J. 
Published: August 2006

AbstractThe neural substrates of fear conditioning in rats have been well characterized, with converging lines of evidence indicating that conditioned stimulus (CS) and unconditioned stimulus (US) information form a CS–US association in the amygdala. Auditory CS information can reach the amygdala via two routes: a direct thalamo‐amygdala pathway, and an indirect thalamo‐cortico‐amygdala pathway. Although either pathway can fully support learning when the alternate pathway is disrupted, many studies to date have argued that the thalamo‐amygdala pathway is the principal auditory CS pathway in intact brains. To test this hypothesis, we trained rats in auditory fear conditioning, and 24 h later lesioned either pathway, leaving the alternate pathway intact. Later, animals were tested for conditioned freezing to the auditory CS. We report that lesions of the thalamo‐amygdala pathway produced severe but incomplete deficits in freezing during the tone retention test, while lesions of the thalamo‐cortico‐amygdala pathway completely abolished freezing during tone presentation. These results suggest that the thalamo‐cortico‐amygdala pathway is the principal auditory CS pathway when the brain is intact.
Local and descending circuits regulate long‐term potentiation and zif268 expression in spinal neurons
Authors: Rygh Lars Jørgen , Suzuki Rie , Rahman Wahida , Wong Yuk , Vonsy Jean Laurent , Sandhu Hardip , Webber Mark , Hunt Stephen , Dickenson Anthony H. 
Published: August 2006

AbstractLong‐term potentiation (LTP), a use dependent long‐lasting modification of synaptic strength, was first discovered in the hippocampus and later shown to occur in sensory areas of the spinal cord. Here we demonstrate that spinal LTP requires the activation of a subset of superficial spinal dorsal horn neurons expressing the neurokinin‐1 receptor (NK1‐R) that have previously been shown to mediate certain forms of hyperalgesia. These neurons participate in local spinal sensory processing, but are also the origin of a spino‐bulbo‐spinal loop driving a 5‐hydroxytryptamine 3 receptor (5HT3‐R)‐ mediated descending facilitation of spinal pain processing. Using a saporin‐substance P conjugate to produce site‐specific neuronal ablation, we demonstrate that NK1‐R expressing cells in the superficial dorsal horn are crucial for the generation of LTP‐like changes in neuronal excitability in deep dorsal horn neurons and this is modulated by descending 5HT3‐R‐mediated facilitatory controls. Hippocampal LTP is associated with early expression of the immediate‐early gene zif268 and knockout of the gene leads to deficits in long‐term LTP and learning and memory. We found that spinal LTP is also correlated with increased neuronal expression of zif268 in the superficial dorsal horn and that zif268 antisense treatment resulted in deficits in the long‐term maintenance of inflammatory hyperalgesia. Our results support the suggestion that the generation of LTP in dorsal horn neurons following peripheral injury may be one mechanism whereby acute pain can be transformed into a long‐term pain state.
Cocaine‐induced locomotor activity and Fos expression in nucleus accumbens are sensitized for 6 months after repeated cocaine administration outside the home cage
Authors: Hope Bruce T. , Simmons Danielle E. , Mitchell Tim B. , Kreuter Justin D. , Mattson Brandi J. 
Published: August 2006

AbstractInduction of the immediate early gene protein product Fos has been used extensively to assess neural activation in the striatum after repeated cocaine administration to rats in their home cages but rarely after repeated administration outside the home cage, which produces more robust locomotor sensitization. In the present study, we found cocaine‐induced Fos expression in nucleus accumbens, but not caudate‐putamen, was enhanced 1 and 6 months after repeated drug administration in locomotor activity chambers. Double‐labelling of Fos protein and enkephalin mRNA indicated that Fos expression in nucleus accumbens was enhanced in enkephalin‐positive, but not enkephalin‐negative, medium spiny neurons. In contrast, cocaine‐induced Fos expression was absent altogether in nucleus accumbens and unaltered in caudate‐putamen 1 month after repeated cocaine administration in the home cage. As cocaine‐induced locomotor activity was also enhanced 1 and 6 months after repeated cocaine administration in locomotor activity chambers, we wanted to confirm that neuronal activity in nucleus accumbens mediates cocaine‐induced locomotor activity using our particular treatment regimen. Bilateral infusions of the GABA agonists baclofen and muscimol (1 µg/side) into nucleus accumbens of sensitized rats blocked cocaine‐induced Fos expression and locomotor activity. Thus, while neuronal activity in both D1‐ and D2‐type neurons in nucleus accumbens can mediate acute cocaine‐induced locomotor activity, the enhanced activation of enkephalinergic D2‐type neurons suggests that these latter neurons mediate the enhancement of cocaine‐induced locomotor activity for up to 6 months after repeated drug administration outside the home cage.
Genetic or pharmacological inactivation of the dopamine D1 receptor differentially alters the expression of regulator of G‐protein signalling (Rgs) transcripts
Authors: Stanwood Gregg D. , Parlaman Joshua P. , Levitt Pat 
Published: August 2006

AbstractDysregulation of dopamine (DA) receptor signalling induces specific changes in behaviour, neuronal circuitry and gene expression in the mammalian forebrain. In order to better understand signalling adaptations at the molecular level, we used high‐density oligonucleotide microarrays (Codelink Mouse 20K) to define alterations in the expression of transcripts encoding regulator of G‐protein coupled receptor signalling in dopamine D1 receptor knockout mice (Drd1a‐KO). Regulator of G‐protein signalling (Rgs) 2, Rgs4, and Rgs9 were significantly decreased in the striatum (STR) of Drd1a‐KO mice. These changes were confirmed by in situ hybridization, and were also observed in the nucleus accumbens (NAc). In contrast, analysis of the medial frontal cortex (MFC) revealed a significant decrease in Rgs17 expression exclusively, and a modest up‐regulation of Rgs5 transcript. The expression of these gene products were not significantly altered in the dopamine‐poor visual cortex (VC). The Drd1a‐KO mouse, and a rabbit model of in utero cocaine exposure, in which D1R signalling is permanently reduced, possess analogous morphological and functional alterations in dopamine‐modulated brain circuits; thus we also examined long‐lasting changes in RGS transcript expression following prenatal exposure to cocaine. In sharp contrast to the Drd1a‐KO, Rgs2 and Rgs4 were unchanged, and Rgs9 and Rgs17 transcripts were increased in prenatal cocaine‐exposed progeny. These data suggest that an absolute absence of D1R signalling (Drd1a‐KO) and hypomorphic D1R signalling (prenatal cocaine) produce common alterations in neuronal morphology, but distinct outcomes in molecular neuroadaptations.
Receptive field structure–function correlates in developing turtle retinal ganglion cells
Authors: Mehta Vandana , Sernagor Evelyne 
Published: August 2006

AbstractMature retinal ganglion cells (RGCs) have distinct morphologies that often reflect specialized functional properties such as On and Off responses. But the structural correlates of many complex receptive field (RF) properties (e.g. responses to motion) remain to be deciphered. In this study, we have investigated whether motion anisotropies (non‐homogeneities) characteristic of embryonic turtle RGCs arise from immature dendritic arborization in these cells. To test this hypothesis, we have looked at structure–function correlates of developing turtle RGCs from Stage 23 (S23) when light responses emerge, until 15 weeks post‐hatching (PH). Using whole cell patch clamp recordings, RGCs were labelled with Lucifer Yellow (LY) while recording their responses to moving edges of light. Comparison of RF and dendritic arbor layouts revealed a weak correlation. To obtain a larger structural sample of developing RGCs, we have looked at dendritic morphology in RGCs retrogradely filled with the tracer horseradish peroxidase (HRP) from S22 (when RGCs become spontaneously active, shortly before they become sensitive to light) until two weeks PH. We found that there was intense dendritic growth from S22 onwards, reaching peak proliferation at S25 (a week before hatching), while RGCs are still exhibiting significant motion anisotropies. Based on these observations, we suggest that immature anisotropic RGC RFs must originate from sparse synaptic inputs onto RGCs rather than from the immaturity of their growing dendritic trees.
Pain management in fulminating ulcerative colitis
Authors: WHITE MICHELLE , SHAH NEIL , LINDLEY KEITH , LLOYD‐THOMAS ADRIAN , THOMAS MARK 
Published: August 2006

SummaryBackground:  Toxic megacolon is a life‐threatening complication of ulcerative colitis (UC) characterized by systemic toxicity, loss of blood per rectum and severe pain. Pain management is challenging in these patients because nonsteroidal anti‐inflammatory drugs may exacerbate bleeding and opioids are contraindicated because they adversely affect bowel peristalsis causing an increased risk of colonic perforation.Methods:  We describe three episodes of fulminating UC in two children in whom ketamine analgesia was used. Our protocol for a low‐dose continuous ketamine infusion with either nurse‐controlled analgesia (NCA) or patient‐controlled analgesia (PCA) bolus administration is presented and a review of the literature regarding the use of ketamine analgesia in children is discussed.Results:  Low‐dose ketamine N/PCA with a continuous background infusion provided satisfactory analgesia and none of our children reported adverse effects.Conclusions:  We have demonstrated the safe and effective use of ketamine analgesia in children with toxic megacolon, a condition in which the child is in severe pain and morphine is contraindicated.
Prolonged use of dexmedetomidine in an infant with respiratory failure following living donor liver transplantation
Authors: ENOMOTO YUKI , KUDO TOYOICHIRO , SAITO TAKASHI , HORI TETSUO , KANEKO MICHIO , MATSUI AKIRA , MIZUTANI TARO 
Published: August 2006

SummaryWe used dexmedetomidine for more than 2 months in a mechanically ventilated infant without serious adverse effects. An infant with liver cirrhosis of unknown cause underwent living donor liver transplantation at the age of 9 months. Long‐term mechanical ventilation was required postoperatively, and midazolam with fentanyl had been used to sedate the patient. They required increase to 1.7 mg·kg−1·h−1 and 3.5 μg·kg−1·h−1, respectively, which were still inadequate. On postoperative day 29, dexmedetomidine was added. The rate of dexmedetomidine infusion was increased gradually to 1.4 μg·kg−1·h−1. It was discontinued temporarily to exclude drug‐induced liver dysfunction. However, without dexmedetomidine, adequate sedation level was unattainable. Liver dysfunction was likely to be attributed to cytomegalovirus infection and after restarting dexmedetomidine, the respiratory condition improved. He was extubated 10 weeks after the operation. Dexmedetomidine was successfully tapered off over the following 2 weeks with no signs of withdrawal. Dexmedetomidine was a useful sedative for an infant who required mechanical ventilation for a prolonged period of time.
A comparison of bilateral infraorbital nerve block with intravenous fentanyl for analgesia following cleft lip repair in children
Authors: RAJAMANI ARVIND , KAMAT VIJAYLAKSHMI , RAJAVEL VARDARAJA PONNAMBALAM , MURTHY JYOTSNA , HUSSAIN SYED ALTAF 
Published: August 2006

SummaryBackground:  The efficacy of analgesia with bilateral infraorbital nerve block and intravenous (i.v.) fentanyl were compared for cleft lip surgery in children.Methods:  Eighty‐two children aged 3 months to 10 years undergoing cleft lip repair were prospectively randomized to one of two groups: bilateral infraorbital nerve block (Group B), or i.v. fentanyl (Group F). Group B (n = 41) received bilateral infraorbital injection of 1 ml 0.25% bupivacaine and 2 ml i.v. saline as control. Group F (n = 41) received 2 μg·kg−1 i.v. fentanyl, and bilateral infraorbital injection of 1 ml saline as control. Pain was evaluated by the incidence of tachycardia, hypertension, and/or modified pain score ≥4. The time to awakening, time to first cry and time to feeding were noted.Results:  Thirty four children (82.9%) in Group B had adequate analgesia compared with 15 (36.6%) in Group F (P < 0.0001, RR of failure 0.27 for Group B). Group B had a mean time to awakening of 5.65 ± 2.52 min (Group F: 9.37 ± 4.50 min; P < 0.0001), time to first cry 32.14 ± 18.22 min (Group F: 28.00 ± 16.27 min; P = 0.3), time to feed 62.05 ± 20.06 min (Group F: 72.44 ± 17.72; P = 0.015), and pain score 2.81 ± 1.38 (Group F: 4.71 ± 1.89; P < 0.0001). There were no major complications.Conclusions:  Bilateral infraorbital block is superior to fentanyl in terms of analgesia, and time to awakening and feeding.
Comparative evaluation of Bispectral Index and Narcotrend Index in children below 5 years of age
Authors: WALLENBORN JAN , KLUBA KARSTEN , OLTHOFF DERK 
Published: August 2006

SummaryBackground:  The use of electroencephalogram (EEG) monitoring devices for assessing the depth of hypnosis is most difficult in children under 5 years of age.Methods:  Forty five children aged 0–60 months were included in a prospective observational study. A direct comparison of the processed EEG variables Bispectral IndexTM (BIS, version 3.4) and Narcotrend® Index (NI, version 2.0AF) was to be achieved by simultaneous recording. The ability of these parameters to differentiate between various clinical states was evaluated by using the prediction probability (Pk). Age‐related effects on the BIS and NI were analyzed by dividing the children into three age groups: 0–6, 7–18 and 19–60 months.Results:  The preanesthesia, conscious children were differentiated from anesthetized patients by the BIS and NI with no overlap (Pk = 1.0). In the awake period the BIS was superior to the NI (Pk to differentiate ‘end of anesthesia’ from ‘awakening’ was 0.97 vs 0.73 respectively; P = 0.002). Patients aged 7–18 months showed higher BIS and NI values in the course of anesthesia than the younger and older children (P = 0.001). On awakening, children aged 0–6 months showed the lowest mean BIS (n.s.) and NI (P = 0.006) values.Conclusions:  The BIS currently seems to be superior to the NI, but age‐related processing algorithms of the raw EEG must be implemented in both BIS and NI in order to be useful in children younger than 5 years of age.
Recombinant activated factor VII (rFVIIa) treatment in infants with hemorrhage
Authors: BRADY KENNETH M. , BLAINE EASLEY R. , TOBIAS JOSEPH D. 
Published: August 2006

SummaryBackground:  Recombinant activated factor VII (rFVIIa) is approved by the FDA for the treatment of bleeding episodes in patients with hemophilia A or B with inhibitors to factor VIII or factor IX. In addition to the FDA‐approved indications, rFVIIa has been anecdotally reported effective for profound bleeding episodes in adult patients without hemophilia, and proven beneficial for adults with intracranial hemorrhage. In the pediatric literature, case reports have been made with apparent clinical improvement seen after the use of rFVIIa for acute life‐threatening bleeding; however, there are limited data regarding its use in infants <4 months of age. We report our experience with rFVIIa in nine infants with severe hemorrhage of diverse etiologies.Methods:  This case series of infants under 4 months with coagulopathy and bleeding treated with rFVIIa was collected from two institutions. We report the age, weight and pre‐rFVIIa laboratory values of the patients as well as the clinical scenario and outcomes.Results:  The nine infants all suffered acute life‐threatening hemorrhage. Two patients were postoperative from cardiac surgery, two with Vitamin K deficiency and intracranial hemorrhage, three with suspected necrotizing enterocolitis and abdominal hemorrhage, and two with pulmonary hemorrhage. The patients ranged in age from 2 days to 4 months, (average age 1 month and average weight 3.3 ± 1.0 kg). Seven of the nine patients had frozen plasma, cryoprecipitate, or platelet administration in failed attempts to correct the coagulation defect prior to receiving rFVIIa. The dose range used in this series was 90–100 μg·kg−1, with 90 μg·kg−1 being the most commonly used dose. The average pre‐rFVIIa INR was 8.7 ± 5.1. Four patients had an immeasurably high INR. All patients had clinical resolution of bleeding after receiving rFVIIa, and seven of nine patients survived.Conclusions:  rFVIIa is a powerful hemostatic drug whose mechanism of action provides a theoretical specificity to sites of tissue injury. In addition to its FDA‐approved uses in hemophiliac patients, this drug has a potential role in the treatment of life‐threatening hemorrhage from multiple causes.
Tracheal intubating conditions and pharmacodynamics following cisatracurium in infants and children undergoing halothane and thiopental‐fentanyl anesthesia
Authors: MEAKIN GEORGE H. , MERETOJA OLLI  A. , PERKINS RUSSELL J. , WAITE IAN , TAIVAINEN TOMI , WIRTAVUORI KARI , MURPHY ANTHONY K. , RAIHA LEENA 
Published: August 2006

SummaryBackground:  The aims of the present study were to determine the tracheal intubating conditions, onset time, duration of action, and hemodynamic responses following the administration of cisatracurium 0.15 mg·kg−1 to infants and children.Methods:  One hundred and eighty‐one infants and children aged 1 month to 12 years were randomized to two groups to receive anesthesia with nitrous oxide–oxygen–halothane (group H) or nitrous oxide–oxygen–thiopental‐fentanyl (group TF). Intubation conditions were assessed 120 s after cisatracurium administration using a 4‐part scale. Neuromuscular transmission was monitored by recording the evoked compound electromyogram of the adductor pollicis.Results:  The proportion of patients with excellent or good intubating conditions was similar in both groups (88 of 90, 98% in group H; 85 of 90, 94% in group TF). However, there was a significantly greater proportion of excellent intubating conditions in group H (79 of 90, 88%) compared with group TF (65 of 90, 72%) (P = 0.01) and recovery time was significantly longer in group H compared with group TF (P < 0.001). There was also a higher proportion of excellent intubating conditions in infants compared with older subjects (P = 0.02) and a shorter onset time (P < 0.001) and longer recovery time (P < 0.001) in younger compared with older patients. Changes in heart rate and arterial pressure were negligible 1 min following the cisatracurium administration.Conclusions:  Cisatracurium 0.15 mg·kg−1 produces acceptable intubating conditions at 120 s in the great majority of infants and children. Anesthesia background and age have significant effects on intubating conditions and duration of action of cisatracurium.
Anesthesia‐related morbidity and mortality after surgery for muscle biopsy in children with mitochondrial defects
Authors: DRIESSEN JACQUES , WILLEMS SIMONE , DERCKSEN SANDER , GIELE JANNEKE , VAN DER STAAK FRANS , SMEITINK JAN 
Published: August 2006

SummaryBackground:  Children with mitochondrial defects (MD) may have an increased risk for cardiorespiratory and neurological complications from anesthesia. The aim of this study was to determine the incidence of perioperative complications and adverse events in children with MD.Methods:  We performed a retrospective review of the anesthesia, surgical and medical records of 155 children up to 10 years who underwent a diagnostic surgical muscle biopsy for suspected mitochondrial and muscle disorders between 1999 and 2003. The data of the 122 patients where a definite MD diagnosis was found were analyzed. Anesthesia was conducted according to the discretion of the attending staff. In children with MD the activity of the different complexes of the oxidative phosphorylation system was measured.Results:  From the preoperative assessment, signs of encephalopathy were most frequent (n = 93), followed by muscle weakness (n = 32), lactic acidosis (n = 15), cardiomyopathy and/or conduction defects (n = 10) and chronic respiratory problems (n = 7). The mean age of the children with MD was 32.4 months (SD = 26.9). The mean duration of anesthesia was 36.0 min (SD = 12.6) and the mean length of stay in the recovery room was 33.0 min (SD = 24.0). There were no major changes in heart rate or blood pressure which required pharmacological intervention during anesthesia or postanesthesia care unit (PACU) stay. A short episode of SpO2 <80% with airway obstruction occurred once in the PACU. Biochemical analysis in the children with a MD showed an isolated deficiency of one of the five protein complexes of oxidative phosphorylation in 42 children, a combination of complex deficiencies in 41 and no definite localization in 39 children.Conclusion:  With standard preoperative assessment, monitoring and anesthesia management, there were no major peroperative and postoperative anesthesia‐related complications in children undergoing surgical muscle biopsy with a MD diagnosis.