Long-term memory was impaired in one-trial passive avoidance task of day-old chicks hatching from hypo-magnetic field space

The retained curve in one-trial passive avoidance task (OTPAT) of day-old chicks hatching from natural geomagnetic field (control groups) is consistent with the acknowledged three-phase model. The two dips are at the 20th min and the 60 min, and the avoidance rates (AR) to the red bead in short- and intermediate-term memory are 68.4% on average, while that in the long-term momory was 74.8%. The OTPAT retained curve of day-old chicks hatching from hypomagnetic field space (experimental groups) presents the marked timing effect. The two dips were at the 25th min and the 50th min, the avoidance rates to the red bead (ARR) in the short- and intermediate-term memory was 74.1% on an average, which was resembled to that in control group; however, the long-term memory appeared an obvious fluctuation. Compared with that in control groups, ARR and the deviation coefficient in experimental groups were decreased by 25.3% and increased by 1.3 times, respectively. That is to say, both the memory ability and stability in the experimental chicks declined. The result shows that the hypomagnetic field space has a negative effect on the development of chick brain function, and that cannot be negligible.

Topography of acoustic response characteristics in the midbrain inferior colliculus of Kunming mouse

Topography of acoustic response characteris-tics of the midbrain inferior colliculus (IC) of the Kunming mouse was studied by using extracellular recording tech-niques. The characteristic frequency (CF) range represented in the different divisions of the IC differed markedly: 4—15 kHz in the dorsal cortex (DC), 10—70 kHz in the centralnucleus (CN), and 4—35 kHz in the external cortex (EC).The CF in the CN increased from dorsal and lateral to ven-tral and medial, higher CFs represented at its ventromedial part and lower CFs at its dorsal part. The isofrequency con-tours of CFs were incurvate. Minimum thresholds (MT) ofthe auditory neurons in DC and the central part of CN were lower (about 10 dB SPL), but considerably higher in thedorsal and ventral region of EC. Results suggest that each of the divisions in the mouse IC may have different auditory functions.

Role of frequency band integration in sharpening frequency tunings of the inferior colliculus neurons in the big brown bat, Eptesicus fuscus

By means of a particular two-tone stimulationparadigm in combination of using a pair of electrodes forsimultaneously recording from two inferior colliculus (IC)neurons, the current in vivo study is undertaken to explorethe role of frequency band integration (FBI) in sharpening offrequency tuning in the big brown bat, Eptesicus fuscus.Three major results are found: (1) The paired neurons cor-related to FBI are located not only within the same frequencyfilter bandwidth (FFB), but also across different FFBs. Therelations of their frequency tuning curves (FTCs) are mainlyof two types: the flank-overlapped and overlaid patterns. (2)Although the sharpness of FTCs between paired neurons ismutual, the sharpening efficiency of neurons located withinthe same FFB is higher than that of neurons across FFBs,and the FTCs of neurons with the best frequencies (BF) of 20--30 kHz are most strongly sharpened. (3) The strength ofFBI is weak near the BF but gradually increased with fre-quencies away from the BF of sound stimuli. This suggeststhat the dynamical FBI of the IC neurons located within and across the FFBs might be involved in the formation of func-tional FFB structures.

Interaction of Neuronal Tau with DNA in Nano-Space

In this study, the binding oftau to DNA is investi-gated by the electrophoretic mobility shift assay. Using polynucleotide as probe, we find that tau bound to dou-ble-stranded DNA but not to single-stranded DNA. For-mation of tau-polynucleotide complex is interfered at alkaline pH and high concentration of NaCl, but is not affected by dithiothreiotol. Electron microscopy reveals that the protein associated with the nucleic acid in a necklace manner. Nevertheless,