Short- and long-term effects of cannabinoids on the extinction of contextual fear memory in rats

Facilitation of memory extinction by manipulation of the endocannabinoid (eCB) system has been recently studied in several paradigms. Our previous results pointed to facilitation of contextual fear memory extinction by a low dose of a cannabinoid agonist, with a suggestion of short-term effects. The aim of the present study was to further investigate the effects of cannabinoid drugs in the short- and long-term extinction of conditioned fear using an extended extinction protocol. Male Wistar rats were placed in a conditioning chamber and after 3 min received a footshock (1.5 mA, 1 s). On the next day, they received i.p. drug treatment (WIN55212-2 0.25 mg/kg, AM404 10 mg/kg, SR141716 A 1 mg/kg) and were re-exposed to the conditioning chamber for 30 min (extinction training). No-Extinction groups received the same drug treatment, but were exposed for 3 min to the conditioning chamber. A drug-free test of contextual memory (3 min) was performed 7 days later. The cannabinoid agonist WI55212-2 and the inhibitor of eCB metabolism/uptake AM404 facilitated short-term extinction. In addition, long-term effects induced by treatments with WIN55212 and AM404 were completely divergent to those of SR141716A treatment. The present results confirm and extend previous findings showing that the eCB system modulates short-term fear memory extinction with long-lasting consequences.     

Men and women holding hands: II. Whose hand is uppermost?

Sex differences in the way men and women hold hands were investigated in a series of six studies. Specifically, it was hypothesized that men would have the uppermost hand in male-female couples holding hands in public significantly more often than women. Also, the American couples observed in Study 1 were classified by height, those in Study 2 by age, those in Study 3 by hand preference, those in Study 4 by ethnic group, and those in Study 6 by sex of initiator of the handholding; the handholding couples in Study 5 were Japanese adults. A combined total of 15,008 handholding couples were observed in these six studies, and across differences in height, age, hand preference, ethnicity, culture, and sex of the initiator of handholding in public, men were significantly more likely than women to have the uppermost hand.     

A quantitative near-infrared spectroscopy study: a decrease in cerebral hemoglobin oxygenation in Alzheimer's disease and mild cognitive impairment

A newly developed quantitative near-infrared spectroscopy (NIRS) system was used to measure changes in cortical hemoglobin oxygenation during the Verbal Fluency Task in 32 healthy controls, 15 subjects with mild cognitive impairment (MCI), and 15 patients with Alzheimer's disease (AD). The amplitude of changes in the waveform, which was quantitatively calculated by a signal processing method, was significantly lower in the frontal, and the bilateral parietal areas in the AD group, whereas that in the MCI group was significantly lower only in the right parietal area. The NIRS system may be a potential tool for the primary screening of AD.     

Effect of unpleasant loud noise on hippocampal activities during picture encoding: an fMRI study

The functional link between the amygdala and hippocampus in humans has not been well documented. We examined the effect of unpleasant loud noise on hippocampal and amygdaloid activities during picture encoding by means of fMRI, and on the correct response in humans. The noise reduced activity in the hippocampus during picture encoding, decreased the correct response and increased the activity of the amygdala. A path diagram using structural equation modeling suggested that hippocampus activity might be depressed by high amygdala activity. Therefore, noise should diminish memory by reducing hippocampal activity, which might be depressed by high amygdala activity.     

Japanese normative set of 359 pictures

This study provides Japanese normative measures for 359 line drawings, including 260 pictures (44 redrawn) taken from Snodgrass and Vanderwart (1980). The pictures have been standardized on voice key naming times, name agreement, age of acquisition, and familiarity. The data were compared with American, Spanish, French, and Icelandic samples reported in previous studies. In general, the correlations between variables in the present study and those in the other studies were relatively high, except for name agreement. Naming times were predicted in multiple regression analyses by name agreement. The full set of the norms and the new pictures may be downloaded from www.psychonomic.org/archive/.     

Formal reasoning in Japanese older adults: The role of metacognitive strategy,task content,and social factors

This study investigated the availability of deductive reasoning competence in late adulthood. Forty-six Japanese older (mean age =71 years) and 58 Japanese young adults (mean age =19.6 years) were assessed for formal or deductive reasoning using Overton's (1990) revision of the four-card selection task. For older adults, metacognitive strategy—operating as a procedure designed to access reasoning competence—resulted in enhanced performance levels. When the semantic content of the reasoning task involved emotional issues, however, the metacognitive strategy failed to facilitate reasoning performance. This suggests that reasoning competence is available in late adulthood but that performance is susceptible to contextual variables. Social factors were not significantly related to older adults' reasoning performance. Thus, assessment of these factors may have been based on too broad a definition to describe adequately the status of the older adults. For the young, only semantic task content was related to reasoning performance.     

Sequential effects in face-attractiveness judgment

A number of studies have shown that current-trial responses are biased toward the response of the preceding trial in perceptual decisionmaking tasks (the sequential effect-Holland and Lockhead, 1968 Perception & Psychophysics 3 409-414). The sequential effect has been widely observed in evaluation of the physical properties of stimuli as well as more complex properties. However, it is unclear whether subjective decisions (e.g., attractiveness judgments) are also susceptible to the sequential effect. Here, we examined whether the sequential effect would occur in face-attractiveness judgments. Forty-eight pictures of male and female faces were presented successively. Participants rated the attractiveness of each face on a 7-point scale. The results showed that the attractiveness rating of a given face assimilated toward the rating of the preceding trial. In a separate experiment, we provided the average attractiveness rating by others for each trial as feedback. The feedback weakened the sequential effect. These findings suggest that attractiveness judgment is also biased toward the preceding judgment, and hence the sequential effect can be extended into the domain of subjective decisionmaking.     

Temporal characteristics of the effects of visual pattern redundancy on encoding and storage processes: evidence from rapid serial visual presentation

Pattern redundancy is a key concept for representing the amount of internal mental load (encoding efficiency) needed for pattern perception/recognition. The present study investigated how pattern redundancy influences encoding and memory processes in the visual system using a rapid serial visual presentation (RSVP) paradigm. With RSVP, it is well known that participants often fail to detect repetitions of words (repetition blindness, RB). We used this phenomenon as an index of the encoding and storage of visual patterns. In three experiments, we presented patterns with higher and lower redundancy, as defined by Garner’s equivalent set size (ESS). The results showed that RB occurred more frequently for higher redundancy patterns when the temporal distance between the targets was less than 500 ms; this tendency was reversed with longer temporal distances of over 500 ms. Our results suggest that pattern redundancy modulates both the early encoding and subsequent memory processes of a representation.     

Atomistic study of structural fluctuations during radiation-induced amorphization in the ordered intermetallic compound NiTi

We have carried out an atomistic study of electron-induced amorphization of an ordered intermetallic compound NiTi by means of in-situ high-resolution high-voltage electron microscopy observations and molecular dynamics simulations. Both theoretical and experimental results show that metastable nanometre-size atomic clusters form and disappear during irradiation, so that a spatiotemporal fluctuation under amorphization is induced. Mean-lifetime measurements of these clusters demonstrate that high-energy particle irradiation provides a useful tool to study dynamic fluctuations of the local atomic structure in the non-equilibrium open systems.