Neurophysiological evidence for categorical perception of color

The aim of this investigation was to examine the time course and the relative contributions of perceptual and post-perceptual processes to categorical perception (CP) of color. A visual oddball task was used with standard and deviant stimuli from same (within-category) or different (between-category) categories, with chromatic separations for within- and between-category stimuli equated in Munsell Hue. CP was found on a behavioral version of the task, with faster RTs and greater accuracy for between- compared to within-category stimuli. On a neurophysiological version of the task, event-related potentials (ERPs) showed earlier latencies for P1 and N1 components at posterior locations to between- relative to within-category deviants, providing novel evidence for early perceptual processes on color CP. Enhanced P2 and P3 waves were also found for between- compared to within-category stimuli, indicating a role for later post-perceptual processes.     

LTP in hippocampal area CA1 is induced by burst stimulation over a broad frequency range centered around delta

Long-term potentiation (LTP) is typically studied using either continuous high-frequency stimulation or theta burst stimulation. Previous studies emphasized the physiological relevance of theta frequency; however, synchronized hippocampal activity occurs over a broader frequency range. We therefore tested burst stimulation at intervals from 100 msec to 20 sec (10 Hz to 0.05 Hz). LTP at Schaffer collateral–CA1 synapses was obtained at intervals from 100 msec to 5 sec, with maximal LTP at 350–500 msec (2–3 Hz, delta frequency). In addition, a short-duration potentiation was present over the entire range of burst intervals. We found that N-methyl-d-aspartic acid (NMDA) receptors were more important for LTP induction by burst stimulation, but L-type calcium channels were more important for LTP induction by continuous high-frequency stimulation. NMDA receptors were even more critical for short-duration potentiation than they were for LTP. We also compared repeated burst stimulation with a single primed burst. In contrast to results from repeated burst stimulation, primed burst potentiation was greater when a 200-msec interval (theta frequency) was used, and a 500-msec interval was ineffective. Whole-cell recordings of postsynaptic membrane potential during burst stimulation revealed two factors that may determine the interval dependence of LTP. First, excitatory postsynaptic potentials facilitated across bursts at 500-msec intervals but not 200-msec or 1-sec intervals. Second, synaptic inhibition was suppressed by burst stimulation at intervals between 200 msec and 1 sec. Our data show that CA1 synapses are more broadly tuned for potentiation than previously appreciated.Long-term potentiation (LTP) is used as a model for studying synaptic events during learning and memory (Bliss and Collingridge 1993; Morris 2003; Lynch 2004). At most synapses, LTP is triggered by postsynaptic Ca²⁺ influx through N-methyl-d-aspartic acid (NMDA) glutamate receptors (Collingridge et al. 1983; Harris et al. 1984; Herron et al. 1986) and, under some conditions, through L-type voltage-gated Ca²⁺ channels (Grover and Teyler 1990, 1994; Morgan and Teyler 1999). LTP was discovered in the dentate gyrus (Bliss and Lomo 1973) following several seconds of 10–100 Hz stimulation of the perforant path. Since then, many LTP studies have used similar long, high-frequency stimulation (HFS) protocols, most typically 100 Hz, 1 sec (Bliss and Collingridge 1993). Although effective, HFS does not resemble physiological patterns of activity (Albensi et al. 2007). Patterned stimulation resembling physiological activity, in particular theta burst stimulation, is also effective for LTP induction (Larson et al. 1986; Staubli and Lynch 1987; Capocchi et al. 1992; Nguyen and Kandel 1997). Theta burst stimulation consists of short bursts (4–5 stimuli at 100 Hz) repeated at 5 Hz, which lies within the hippocampal theta frequency range (4–12 Hz) (Bland 1986; Buzsáki 2002). Primed burst stimulation, another form of patterned stimulation, involves delivery of a priming stimulus followed by a single short burst (Larson and Lynch 1986; Rose and Dunwiddie 1986). The temporal requirements for primed burst LTP are quite precise (Diamond et al. 1988; Greenstein et al. 1988; Larson and Lynch 1989): Intervals less than 140 msec or greater than 200 msec are ineffective.The mechanisms underlying theta frequency-dependent LTP have been studied primarily using the primed burst protocol (Larson and Lynch 1986, 1988, 1989; Pacelli et al. 1989; Davies and Collingridge 1996). Activation of GABA_B autoreceptors during the priming stimulus suppresses GABA release during the following burst (Davies et al. 1990; Lambert and Wilson 1994; Olpe et al. 1994), allowing greater postsynaptic depolarization (Larson and Lynch 1986; Pacelli et al. 1989) and more effective NMDA receptor activation (Davies and Collingridge 1996). Consequently, temporal requirements for primed burst potentiation match the time course of GABA_B autoreceptor-mediated suppression of GABA release (Davies et al. 1990; Davies and Collingridge 1993; Mott et al. 1993).Besides theta, hippocampal activity is observed at other frequencies, notably sharp waves (0.01–5 Hz) (Buzsáki 1986, 1989; Suzuki and Smith 1987) and low-frequency oscillations (≤1 Hz) (Wolansky et al. 2006; Moroni et al. 2007). These lower frequencies dominate during slow wave sleep (Buzsáki 1986; Suzuki and Smith 1987; Wolansky et al. 2006; Moroni et al. 2007), and contribute to hippocampal memory processing (Buzsáki 1989; Pennartz et al. 2002). While synchronized population activity over frequencies from <1 Hz to 12 Hz is associated with hippocampal memory function, previous LTP studies have focused on theta. We therefore investigated burst stimulation at frequencies from 0.05 Hz to 10 Hz. We found that CA1 synapses potentiate to some degree over this entire range and that maximal potentiation occurs around delta frequency rather than theta.     

Adaptive training leads to sustained enhancement of poor working memory in children

Working memory plays a crucial role in supporting learning, with poor progress in reading and mathematics characterizing children with low memory skills. This study investigated whether these problems can be overcome by a training program designed to boost working memory. Children with low working memory skills were assessed on measures of working memory, IQ and academic attainment before and after training on either adaptive or non‐adaptive versions of the program. Adaptive training that taxed working memory to its limits was associated with substantial and sustained gains in working memory, with age‐appropriate levels achieved by the majority of children. Mathematical ability also improved significantly 6 months following adaptive training. These findings indicate that common impairments in working memory and associated learning difficulties may be overcome with this behavioral treatment.     

Assessment of stress-buffering effects of social networks on psychological symptoms in an inner-city elderly population

Social network researchers have been divided into two camps: those who propose that social networks have a direct effect on subsequent psychological symptoms and those who posit a stress-buffering effect as well. Previous research has been limited by rudimentary measures of social interaction and the absence of longitudinal data as well as by different approaches to the assessment of possible buffering effects. In the present study, using 19 social network variables, the authors followed 133 elderly residents of mid-Manhattan SRO hotels for 1 year. Three different methods of determining buffering effects were examined: Dividing the sample into high- and low-stress groups and contrasting differences in percentage variance accounted for by social networks between the two groups; Examining the group as a whole to assess if any Network Variable X Stress interactional terms are significant; Examining the group as a whole to assess whether there is a reduction in the beta value of stress with respect to psychological symptoms when network variables are added to the analysis. Method 1 indicated a direct network effect, but none of the methods indicated a buffering effect. Of clinical relevance was the nonlinearity of the network effects, that is, depending upon a person's stressor level, different network dimensions must be emphasized and strengthened.     

The timing of psychosocial transitions and changes in women's lives: an examination of women aged 45 to 60

Sixty-four middle-class women from four cohorts aged 45, 50, 55, and 60 participated in a retrospective interview concerning psychosocial changes in their adult lives. Their responses provided self-report data relating to specific psychosocial changes, and judges who read the interview protocols provided independent ratings of major psychosocial transitions. The results indicated that major psychosocial transitions were more likely to be associated with phases of the family cycle than with chronological age; within the family cycle, transitions were more likely to occur during the preschool (28% of the women), launching (42% of the women), and postparental (33% of the women) phases than during the no children, school-age, or adolescent phases; transitions associated with the preschool and launching phases were characterized by dissatisfaction, personal disruption, marital unhappiness, and decreased personal development, whereas transitions associated with the postparental phase were characterized by personal mellowing and improved marital relations; and finally, numerous self-reported psychosocial changes were associated with family cycle phase, and a small number of changes was associated with chronological age.     

RELIGION IN AN AGE OF SCIENCE; METAPHYSICS IN AN ERA OF HISTORY

Abstract. Ian Barbour's Religion in an Age of Science is a welcome systematic, theoretical overview of the relations between science and religion, culminating his long career with a balanced and insightful appraisal. The hallmarks of his synthesis are critical realism, holism, and process thought. Barbour makes even more investment in process philosophy and theology than in his previous works. This invites further inquiry about the adequacy of a highly general process metaphysics in dealing with our particular, deeply historical world; also further inquiry about the adequacy of its panexperientialism and incrementalism.     

Supervisory styles index: Examining supervisees' perceptions of Supervisory Style

The goal of this research was to develop an instrument, the Supervisory Styles Index (SSI), that would examine supervisory style. Style has been described as the way in which the personality and convictions of the supervisor are demonstrated in the supervisory relationship (Leighton, 1991). This study focuses on the interplay between supervisory style and the influence of sex and gender. The findings of this study reveal that female supervisees discern their supervisors to be more self-disclosing than do male supervisees. Implications of the findings and utilization of the index are discussed.Portions of this paper were presented at the 52nd annual conference of the American Association for Marriage and Family Therapy, Chicago, Illinois, November, 1994.     

Culture change: A training program for recent immigrant professionals from the former Soviet Union

The article describes a training program in structural/integrative family therapy for immigrant professionals from the former Soviet Union at the Training Center of the Shiluv Institute for Family and Couple Therapy in Jerusalem. The program was instituted to meet the pressing needs of a mass immigration of half a million people that came to Israel between 1990 and 1992. This is a retrospective look at the journey of the initial group of psychiatrists and psychologists who changed country, culture, language, and professional orientation in just two years. The authors state their conclusions as to the most expedient way to organize therapy for families from the former Soviet Union — a population in need of help but lacking an awareness of therapy and suspicious of the outsider.