Neuronal mechanisms of learning in teleost fish / Mecanismos neuronales del aprendizaje en los peces teleósteos

Se revisaron dos aproximaciones al estudio de la neurobiología del aprendizaje en peces teleósteos: lesiones cerebrales y estimulación química. Respecto al efecto de lesiones cerebrales, la literatura reporta que las ablaciones del telencéfalo producen deficiencias en habituación, mientras que las lesiones en el cerebelo afectan el condicionamiento clásico de retracción ocular y aprendizaje espacial (efectos similares observados en mamíferos sugieren que las funciones del cerebelo pudieron haber evolucionado tempranamente en la historia de los vertebrados). Áreas del Medium Pallium (MP) parecen ser vitales en el aprendizaje emocional de los peces; más aún, las funciones del MP aparentan ser similares a las de la amígdala en mamíferos. Con respecto a procesos neuroquímicos, los antagonistas de los receptores NMDA, mostraron afectar la adquisición de condicionamiento de evitación y miedo. Por último, el óxido nítrico y el guanosín monofosfato cíclico han sido relacionados con los procesos de consolidación del aprendizaje emocional.

Two predominant approaches for studying the neurobiology of learning in fish are reviewed: brain lesions and chemical stimulation. Habituation, sensitization, Pavlovian Conditioning, spatial behavior, and emotional learning are the specific processes analyzed. Regarding the effect of brain lesions, telencephalic ablations produced impairment of habituation learning; conversely, cerebellum lesions caused deficiencies in classical conditioning of eye-retraction and spatial learning (similar effects observed in mammals suggest that the functions of the cerebellum may have evolved early in vertebrate history). Medium Pallium (MP) areas have been identified as critical for emotional learning in fish. Furthermore, neurobehavioral functions of MP seem to be similar to the functions of the amygdala in mammals. Relating to neurochemical processes, NMDA receptor antagonists affected the acquisition of avoidance and fear conditioning in a dose-dependent manner. Alternatively, Nitric Oxide (NO) and cyclic Guanosine Monophosphate (cGMP) seem to be involved in the consolidation process of emotional learning.

Microstructure and ultrastructure changes of multiple organ tissue and hemodynamic effects in swine after cardiopulmonary resuscitation / 中华急诊医学杂志

Objective To investigate the microstructure and ultrastructure changes of cardiac muscle, pallium, lung, liver and kidney tissue and hemodynamic effects after the success of cardiac arrest (CA)-cardiopulmonary resuscitation(CPR) of swine. Method A total of 16 Beijing swine(weight 29 ～ 35 kg)were randomly (random number) divided into normal-control group ( n = 8) and standard CPR group ( n = 8). The swine of the former group were only given anesthetized and intubated, without ventricular fibrillation and CPR. The swine of the latter group were given standard CPR after 4 min of untreated VF, from 10 min after restoration of spontaneous cirkg) and keep for 6 h. And cardiac output (CO), left ventricular maximal rate of systolic pressure ( + dp/dtmax),maximum reduction of left ventricular diastolic velocity ( - dp/dtmax), heart rate (HR) and mean arterial pressure (MAP) of these animals before ventricular fibrillation and 0.5 h, 2 h, 4 h, 6 h after ROSC have been monitored.All swine were put to death after 6 h,and got their cardiac apex, pallium, left lung, right lobe of liver and upper pole of left kidney quickly for microstructure and ultrastructure studies. Statistical analysis was performed using two paired samples t test. Results At different time points after restoration of spontaneous circulation, the cardiac output (CO),left ventricular maximal rate of systolic pressure ( + dp/dtmax), maximum reduction of left ventricular diastolic velocity (- dp/dtmax) were significantly lower than before ventricular fibrillation, with significant difference ( P ＜ 0.05). And HR of different time points were increased significantly ( P ＜ 0.05), with no significantly difference between MAP of each time points ( P ＞ 0.05). Compared with the normal-control group, the cardiac muscle, pallium, lung, liver and kidney tissue of the swine in standard CPR group were found different degree of damages in their microstructure and ultrastructure sections. The damages of the cardiac muscle, pallium, and lung tissue were more obviously. Conclusions Sudden cardiac arrest(CA)-cardiopulmonary resuscitation(CPR) could cause different degree of damages and hemodynamic effects on the body, through our ROSC 6 h model, the damages of the cardiac muscle, pallium and lung were more severity, the damages of liver and kidney were lighter.

L-histidine reduces inhibitory avoidance in Carassius auratus submitted to cerebellar ablation

The effect of post-training treatment with L-histidine (LH) on the memory consolidation of inhibitory avoidance was investigated in Carassius auratus submitted to cerebellar ablation. The inhibitory avoidance procedure included 3 days: one habituation day, one training day (5 trials, T1-T5) and one test day. On the training day, each fish was placed individually in a white compartment separated from a black compartment by a sliding door. When the fish crossed into the black compartment, a weight was dropped in front of it (aversive stimulus) and the time to cross was recorded. Saline or LH (100 mg/kg) was injected intraperitoneally 10 min after the trials. Data were log10 transformed and analyzed by ANOVA and the Student-Newman-Keuls test (P < 0.05). In T5, all groups [ablation/LH (N = 15; 189.60 ± 32.52), ablation/saline (N = 14; 204.29 ± 28.95), sham/LH (N = 14; 232.36 ± 28.15), and sham/saline (N = 15; 249.07 ± 25.82)] had similar latencies that were significantly higher than T1 latencies [ablation/LH (89.33 ± 20.41), ablation/saline (97.00 ± 25.16), sham/LH (73.86 ± 18.42), and sham/saline (56.71 ± 17.59)], suggesting acquisition of inhibitory avoidance. For the test, there was a significant reduction in latencies of ablation/LH (61.53 ± 17.70) and sham/saline (52.79 ± 25.37) groups compared to the ablation/saline (213.64 ± 29.57) and sham/LH (199.43 ± 24.48) groups, showing that cerebellum ablation facilitated retention of inhibitory avoidance and LH reversed the effect of ablation. The results support other evidence that LH impairs memory consolidation and/or reduces the interpretation of aversion value.

Gastric Syphilis Mimicking Adenocarcinoma: A Case Report

Syphilis is an unexpected diagnosis in the stomach, and the reduced incidence of syphilis has made its clinical presentation less widely appreciated. We report a 43-yr-old man suffering from epigastric tenderness with an initial diagnosis of gastric carcinoma; gastric syphilis was confirmed by demonstrating spirochetes in a gastric biopsy specimen by silver impregnation. Excessive lymphoplasmacytic infiltration with diffuse thickening of gastric rugae should raise suspicion of gastric syphilis, which should be considered in the differential diagnosis of diffuse erosive gastritis and infiltrative lesions of the stomach.

The effects of infrasound on the ultrastructure of the rat pallium / 中华物理医学与康复杂志

Objective To further investigate the threshold value and the dose-effect relationship of infrasound on the rat pallium, and to observe the effects on the pallium's ultrastructure. Methods Rats were exposed to 16 Hz, 90 dB infrasound for 2 hours daily. With a transmission electron microscope, changes in the ultrastructure of the cortex of the rats' parietal lobes were observed 2 hours, 3 days and 7 days after the treatment. Results There were no changes in the ultrastructure of the pallium in rats which had been exposed for 7 days or 14 days. Denaturation appeared when the rats had been exposed for 21 days, 28 days or 35 days. Denaturation become more serious as the exposure time increased beyond 21 days. Denaturation and damage gradually returned to normal with time after exposure. Conclusion 16 Hz, 90 dB infrasound exposure over an extended time may cause denaturation and other changes in the ultrastructure of the pallium in rats. Such changes can return to normal with time.