post-sleep recognition performance

e182

Abstracts / Neuroscience Research 68S (2010) e109–e222

P1-m04 Sema4D/CD100 deficiency leads to superior performance in mouse motor behavior

Takuji Ito 1 , Tetsuji Tanaka 2 , Kenji Yoshida 1 , Noriko Takeuchi 1 , Hitoshi Kikutani 3 , Atsushi Kumanogoh 4 , Kazunori Yukawa 1 1

Dept Physiol, Fac of Pharm, Meijo Univ, Nagoya 2 Dep. of Obstetrics & Gynecology, Wakayama Med. Univ 3 Dep. of Molecular Immunology, Research Institute for Microbial Diseases, Osaka Univ 4 Dep. of Immunopathology, Research Institute for Microbial Diseases, Osaka Univ Sema4D/CD100 is a type of class 4 semaphorin, exhibiting crucial roles in growth cone guidance in developing neurons. However, direct evidence of the actual involvement of Sema4D in the neuronal network development crucial for neurobehavioral performance is still lacking. To examine whether Sema4D deficiency leads to abnormal behavioral development, both wild-type and Sema4D-deficient mice were subjected to behavioral analyses including open-field, adhesive tape removal, rotarod tests and a water maze task. Open-field tests revealed increased locomotor activity in Sema4D-deficient mice with less percentage of time spent in the center of the field. In both the adhesive tape removal and rotarod tests, which examine motor coordination and balance, Sema4D-deficient mice showed significantly superior performance, suggesting facilitated motor behavior. Both Sema4D-deficient and wild-type mice successfully learnt the water maze task, locating a hidden escape platform, and also showed precise memory for the platform position in probe tests. However, the swimming speed of Sema4D-deficient mice was significantly faster than that of wildtype mice, providing further evidence of their accelerated motor behavior. Thus our mouse behavioral analyses revealed enhanced motor activity in Sema4D-deficient mice, suggesting the crucial involvement of Sema4D in the neurodevelopmental processes of the central structures mediating motor behavior in mice. doi:10.1016/j.neures.2010.07.2377

P1-m05 Development of a rat model for transcranial direct current stimulation (tDCS): effectiveness measurement using fMRI Yuji Takano 1 , Takashi Yokawa 3 , Asami Masuda 3 , Jun Niimi 3 , Satoshi Tanaka 4 , Naoyuki Hironaka 1,2 1 Human and Information Science Laboratory, NTT Communication Science Laboratories, Kanagawa, Japan 2 CREST, Japan Science and Thechnology Agency, Kanagawa, Japan 3 BioView, Inc., Tokyo, Japan 4 National Institute for Physiological Sciences, Aichi, Japan

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique and has been received a lot of attention in recent years. However, the mechanism of action of tDCS remains unclear. Then we developed a rat model of tDCS and measured its effectiveness with functional magnetic resonance imaging (fMRI). Rats were anesthetized with urethane, sheared around their head and neck, and placed in a stereotaxic apparatus. Carbon fiber electrodes were placed on the front head and neck, and we started recording of fMRI. After baseline recording, we stimulated by passing 400 ␮A (n = 6) or 40 ␮A (n = 6) current for 10 min (an electrode on front head was positive). The averaged signal intensity of fMRI was calculated before and after stimulation, and compared between 400 ␮A and 40 ␮A. As a result, the signal intensities in the frontal cortex and the nucleus accumbens were significantly increased by 400 ␮A stimulation. This finding suggests that front head simulation induce neural activities in the proximate and its connected brain region. The rat model of tDCS we developed is useful to investigate more detailed mechanisms and clinical effectiveness of tDCS. doi:10.1016/j.neures.2010.07.2378

P1-m06 No association between the COMT polymorphism and Beck youth inventories scores in a Chinese cohort Chun-Yen Chang 1 , Ting-Kuang Yeh 1 , Chung-Yi Hu 2 , Chien-Hua Hsiao 1 , Fu-Tai Chuang 1 1

Science Education Center, National Taiwan Normal University Taiwan University

2

National

The COMT 158Met allele may be advantageous for PFC-related cognitive abilities; however, it is also associated with increased emotional vulnerability in response to stress or educational adversity. Previously, we found that students who were homozygous for the Met allele tended to perform more poorly in all components of the Taiwanese Basic Competency Test, a national

standardized test that measures educational achievement, than students who were homozygous or heterozygous for the Val allele. We speculated that affective factors might overwhelm cognitive abilities in high-stake tests. In this study, we present our preliminary attempts to explore the association between COMT polymorphism and emotion of students. Totally, 703 Taiwanese tenth-grade volunteers were recruited. Scores from the Beck youth inventories were used to evaluate students’ self-concept, anxiety, depression, delinquency, and anger. The three genotype groups did not show any significant differences with respect to all subscales in BYI. However, COMT 158Met/Met homozygous students showed a trend towards better performance in all subscales of the BYI. These findings provide evidence that COMT polymorphism might not be a major determinant of students’ affect behaviors of BYI as previously thought. doi:10.1016/j.neures.2010.07.2379

P1-m07 Long-term appetitive memory in the nematode C. elegans Saori Nishijima , Hisayuki Amano, Ichiro Maruyama Information Process Biology Unit, Okinawa Institute of Science and Technology, Okinawa Learning and memory are essential for all animals to survive and reproduce. C. elegans is an excellent model organism for the study of learning and memory for a number of reasons. For instance, the C. elegans nervous system consists of only 302 neurons. The neural circuits of these invariant neurons have completely been reconstructed from serial thin sections using electron microscopy. The body is transparent throughout the life so that neural activities can be observed using Ca2+ - and voltage-sensitive fluorescent proteins in living animals. In this study, we developed a paradigm for the study on learning and memory in C. elegans by classical conditioning of worms with nonanol, as a conditioned stimulus (CS), and potassium chloride (KCl) as an unconditioned stimulus (US). Before the training, worms avoided nonanol, an aversive olfactory stimulus, and were attracted by KCl, an appetitive gustatory stimulus, in chemotaxis assay. In contrast, trained worms were attracted to nonanol after eight-cycle massed (without intertrial intervals, ITI) or spaced (with 10-min ITI) training. Memory induced by the massed training was extinguished within an hour, while the spaced training induced the memory which was retained for 24 h. Worms treated with cycloheximide or actinomycin D failed to form the long-lasting memory by the spaced training, whereas the memory induced by the massed training was not significantly affected. These results indicated that the memory formation by the spaced training, but not by the massed training, required protein synthesis and mRNA transcription. Therefore, the memories induced by the massed and spaced training are classified as short-term and longterm memories, respectively. In support of this, C. elegans mutants defective in nmr-1 encoding an NMDA receptor subunit failed to form both of the shortterm and long-term memory, while mutations in crh-1 encoding the CREB transcription factor affected only on the formation of the long-term memory. doi:10.1016/j.neures.2010.07.2380

P1-m08 Event-related potential during memory encoding of words analyzed by pre/post-sleep recognition performance Ayumi Sashi 1 , Naoyuki Emata 1 , Satoshi Fujii 2 , Takeshi Aihara 1,3 , Hiroshi Sasaki 3 1

Graduate School of Engineering, Tamagawa Univ, Tokyo 2 Dept Physiol, Yamagata Univ, Yamagata 3 College of Engineering, Tamagawa Univ, Tokyo

Event related potential (ERP) during memory encoding of words was investigated by means of the analysis with pre/post-sleep recognition performance. Eight normal right-handed volunteers (mean age = 21.1, four males and four females) gave written informed consent to participate in this study. ERP data was acquired while participants saw and incidentally memorized visually presented words each of which was composed of two kanji characters (encoding phase). Participants had a 0–90 min sleep during 120 min period after encoding phase. Two hundreds words were presented every 2500–2900 ms during encoding phase. Immediately after (pre-sleep recognition phase) and 120 min after (post-sleep recognition phase) the encoding phase, recognition test for one hundred memorized words visually displayed with additional one hundred novel words (also composed of two kanji characters) in each recognition phase were carried out. Thirty-three recording Ag/AgCl sintered electrodes were placed on the scalp based on the 10-20 international standard. ERP signals referenced to left earlobe were amplified

Abstracts / Neuroscience Research 68S (2010) e109–e222

and band pass filtered from 0.05 Hz to 200 Hz, and acquired at sampling rate of 1 kHz by using SynAmps2. Recorded potentials were classified according to whether each word was later remembered or not. This procedure was applied to both recognition phases. Differences in potentials related to later remembered words in pre-sleep recognition phase and post-sleep recognition phase were analyzed. Larger ERP component around 500 ms post-stimulus elicited by later remembered words in post-sleep recognition phase was found compared to pre-sleep recognition phase. These data suggested that the neural activities around 500 ms post-stimulus may predict later remembered or forgotten, and these activities might play an important role in sleep related memory consolidation processes. doi:10.1016/j.neures.2010.07.2381

P1-m09 Difference of functional connectivity of the hippocampo-prefrontal pathway between quiescent and urethane-anesthetized states in rats Sei-etsu Fujiwara , Tatsuo Akema, Yoshinori Izaki Department of Physiology, St. Marianna University School of Medicine Functional connectivity is an important aspect for understanding information representation in the brain’s neuronal networks. The functional connection between the posterior hippocampus (HPC) and the medial prefrontal cortex (PFC) can play a salient role in information processing because of these regions involvements in learning and memory, direct anatomical connection. Based on results of some learning experiments, their functional relation has been reported. Previously, we reported that significant peak of cross-correlogram(CC) between HPC and PFC can be detected based on multiple unit activities (MUAs) in urethane-anesthetized rats. The CCs can be classified into 2 types by the shapes: type HP (the HPC mainly fired before the PFC) and type PH (the PFC mainly fired before the HPC), and can be useful as a measure of functional connectivity between the HPC and PFC. Urethane anesthesia induces slow wave oscillation in the cortical neuronal activities mimicking cortical up/down state as seen in slow wave sleep. And synchronous firing between the HPC and PFC occurring in the up state is thought to information flow for memory function. In the present study, MUAbased CCs were analyzed in awake-quiescent rats, and which was compared with urethane-anesthetized rats. In quiescent state rats, significant peaks of CCs were also observed, however, only type HP was observed. The peak width and height of CCs were significantly narrow and low than those of urethane anesthetized rats. Furthermore, there were significant short peak lags in quiescent rats compared with urethane-anesthetized rats. These differences of the CCs between anesthetized and quiescent states suggest that the functional connectivity between HPC and PFC during quiescent states is different in information processing manor from urethane anesthesia.

e183

more effort to recall them with time. The time-dependent increase of the delta-alpha activity with correctly judged words may reflect increasing ambiguity in the recall process. The hypothesis is consistent with larger power of the delta-alpha activity with the words that subjects failed to correctly judge, since with those words they were more likely to be ambiguous regardless of time interval. Getting together, our results suggest that the delta-alpha activity reflect ambiguity in the recall of memorized items, as well as ambiguity of once memorized items which increases with time. doi:10.1016/j.neures.2010.07.2383

P1-m11 Roles of intra-hippocampal de novo mRNA and protein synthesis in long-term spatial working memory in rats Takaaki Ozawa , Kazuo Yamada, Yukio Ichitani Dept of Behav Neuro, Univ of Tsukuba,Ibaraki We examined the roles of intra-hippocampal de novo mRNA and protein synthesis in each process of long-term spatial working memory including encoding, consolidation, retention and retrieval using delay-interposed radial arm maze task (dRAM). In experiment 1, male rats were trained to perform accurately on 8-arm radial arm maze task (RAM) in which a delay of 6 h was interposed after the fourth correct choice, then we tested the effects of intra-hippocampal administration of 5,6-dichloro-1-␤ribofuranosylbenzimidazole (DRB), a mRNA synthesis inhibitor, in various timings within a trial. DRB before the second-half of the trial impaired the subsequent performance, while that before the first-half did not, suggesting that hippocampal de novo mRNA synthesis is required for the retrieval process, but not for encoding/consolidation processes. In experiment 2, we tested the effects of intra-hippocampal emetine (EME), a protein synthesis inhibitor, in the dRAM using the rats tested in experiment 1. In contrast to DRB, EME before the first-half and that before the second-half impaired the second-half performance suggesting that hippocampal de novo protein synthesis is required both for encoding/consolidation and retrieval processes in dRAM. However, EME before the trial did not impair the non-delayed RAM performance, which requires only encoding and short-term maintenance of spatial information. Therefore, de novo protein synthesis is suggested to be important for consolidation rather than encoding process. Further, EME immediately after the first-half did not impair the second-half performance. This suggests that de novo protein synthesis-dependent consolidation process may finish rapidly after the first-half performance. In conclusion, these results suggest that (1) rapid memory consolidation in dRAM depends on hippocampal de novo protein synthesis, but not on mRNA synthesis, and (2) memory retrieval in dRAM requires hippocampal de novo mRNA and protein synthesis. doi:10.1016/j.neures.2010.07.2384

doi:10.1016/j.neures.2010.07.2382

P1-m10 Increasing gamma-alpha band activity with recall of ambiguous long-term memory Tetsu Jyo 1,2 , Minoru Kawasaki 1,2 , Hideki Ishiyama 1,2 , Naoko Kasai 1,2 , Yumie Ono 1,2

Nojo 1,2 , Atushi

1

School of Advanced Science and Engineering, WASEDA UNIVERSITY 2 Dept. of Physiology a Neuroscience Kanagawa Dental College

We studied evoked EEG reflecting long-term memory recall. Five healthy young subjects participated in the experiment. Subjects first memorized 60 English words (TARGET), each of which was randomly shown on the screen six times. Each subject participated word-recall test with recording EEG three times immediately, one week, and two week after they memorized a TARGET words. In the word-recall test, we used a word list consisted with TARGET and the other 90 English words (DUMMY). Each word in the list was randomly presented to the subject and they were asked to judge whether the presented word is TARGET or DUMMY. We separately averaged the evoked EEG with four conditions of TARGET-correct, TARGET-false, DUMMY-correct, and DUMMY-false. There was no clear relationship between the condition and the time-related change in amplitude and time-frequency analysis using short-time Fourier transform (STFT) of P300 component. However, STFT showed the power of delta-alpha activity 150-300 ms in the parietal lobe tends to increase with the time interval after they memorized TARGET when they correctly judged the word. By contrast, when they failed to correctly judge the word, the power of the delta-alpha activity was much larger than that in the former case and did not change with the time interval. Since the memory of memorized words gradually become obscure, subjects required

P1-m12 Directed forgetting in radial maze behavior in rats: Analysis of activated brain areas by c-Fos immunohistochemistry Kaku Masami 1,2 , Kazuo Yamada 1 , Yukio Ichitani 1 1

Dept Behav Neurosci, Univ of Tsukuba, Ibaraki 2 Med Sci, Ibaraki Pref Univ of Health Sciences, Ibaraki “Directed forgetting (DF)” is shown as impaired performance on a memory test following an instruction that the presented item(s) will not be tested. This phenomenon may reflect the ability of organisms to actively suppress memory or forget previously acquired information. Evidence of DF has been obtained from studies using human and pigeons, but very few studies have been conducted on DF in rats. Here we show rats can actively control previously acquired spatial information using radial arm maze (RAM). After rats made four correct choices in the first-half of a trial in room A, a 2h delay was interposed. In this period rats were placed in a white or black box, which signaled whether the second-half in room A would (remember (R)-trial) or would not (forget (F)-trial) occur after the delay. In R-trials, rats were required to choose the four arms that had not been chosen in the first-half. In F-trials, rats were required to perform a standard RAM task in another room (room B). After R- and F-trials were repeated, a “probe test” in which rats were required to choose the rest arms in the second-half in room A (as in the R-trial) even after the F-cue was presented in delay period was conducted. As a result, rats made more errors in the probe test than in the R-trial. These results demonstrate that DF occurs in rats and suggest rats can control long-term working memory. Next, we examined expression of the