Astrocytes and developmental white matter disorders

There is an increasing awareness that the astrocytes in the immature periventricular white matter are vulnerable to ischemia and respond to inflammation. Here we provide a synopsis of the articles that have evaluated the causes and consequences of developmental brain injuries to white matter astrocytes as well as the consequences of several genetic mutations that result in abnormal astrocyte development. Emerging data suggest that the astrocytes are not simply responding to the injury but are likely victims as well as culprits. Given the important roles that astrocytes play in maintaining ionic, neurotransmitter, and metabolic homeostasis in the brain, a more thorough understanding of the mechanisms that lead to their incapacitation, demise, or reactions as well as a better understanding of the stimuli that regulate their neuroprotective and regenerative properties will enable these cells to be manipulated to preserve the integrity of white matter and to potentially provide therapeutics to enhance neonatal regeneration and recovery from brain injury.     

Invalid results from the method of constant stimuli

The Method of Constant Stimuli was shown to produce constant errors in the direction expected by E. In an experiment, 89 Ss compared variable lines with a standard, each S producing a psychometric function and Point of Subjective Equality (PSE). Four groups differed in the particular range of variable stimuli used; whether the stimuli averaged longer or shorter than the standard, and whether they had a wide or narrow range. All sets of variable stimuli encompassed the standard. PSE was consistently between the standard and the mean of the variables, as predicted by Adaptation Level Theory. In many experiments, the set of variables is chosen on the basis of theory or pilot studies; the present study shows that PSE will be spuriously drawn toward the center of the variables, hence toward E’s pre-experimental expectations.     

PREDICTION OF WORK RELEASE SUCCESS AT A FEDERAL CORRECTIONAL INSTITUTION USING THE MMPI

A pilot study was conducted at a federal correctional institution to determine the extent to which personality factors, as measured by the Minnesota Multiphasic Personality Inventory (MMPI), were related to work release success. The results indicated that only one MMPI scale (Pa) was significantly related to an inmate's success in the work release program. Implications for further research are discussed in the article.     

Capacity and limits of associative memory in pigeons

How much information can a brain store over a lifetime’s experience? The answer to this important, but little researched, question was investigated by looking at the long-term visual memory capacity of 2 pigeons. Over 700 sessions, the pigeons were tested with an increasingly larger pool of pictorial stimuli in a two-alternative discrimination task (incremented in sets of 20 or 30 pictures). Each picture was randomly assigned to either a right or a left choice response, forcing the pigeons to memorize each picture and its associated response. At the end of testing, 1 pigeon was performing at 73% accuracy with a memory set of over 1,800 pictures, and the 2nd was at 76% accuracy with a memory set of over 1,600 pictures. Adjusted for guessing, models of the birds’ performance suggested that the birds had access, on average, to approximately 830 memorized picture—response associations and that these were retained for months at a time. Reaction time analyses suggested that access to these memories was parallel in nature. Over the last 6 months of testing, this capacity estimate was stable for both birds, despite their learning increasingly more items, suggesting some limit on the number of picture—response associations that could be discriminated and retained in the long-term memory portion of this task. This represents the first empirically established limit on long-term memory use for any vertebrate species. The existence of this large exemplar-specific memory capacity has important implications for the evolution of stimulus control and for current theories of avian and human cognition.     

Psychometric properties of the revised UCLA Loneliness Scale and two short-form measures of loneliness in Zimbabwe.

The cross-cultural reliability in Zimbabwe of the Revised University of California at Los Angeles (UCLA) Loneliness Scale and two short forms of the Revised UCLA Loneliness Scale were investigated. Subjects comprised a sample of 1,354 adolescents and another sample of 754 adults. The reliability of the Revised UCLA Loneliness Scale was acceptable. The internal consistency of an eight-item short form of the Revised UCLA Loneliness Scale was adequate, but the reliability of a four-item short form was low. Factor analysis of the Revised UCLA Loneliness Scale, which yielded two factors similar to those reported in North America by Zakahi and Duran (1982) supported the construct validity of the Revised UCLA Loneliness Scale in Zimbabwe. The Revised UCLA Loneliness Scale and the eight-item short form were highly correlated, but this association was spuriously elevated by the fact the eight-item short form is part of the full scale. Factor analysis of the eight-item short form suggested that this scale does not consistently reflect the factor structure of the full scale. We concluded that the Revised UCLA Loneliness Scale possesses acceptable reliability and factorial validity in Zimbabwe and that the eight-item version is superior to the four-item form of the Revised UCLA Loneliness Scale as a short loneliness measure. However, additional refinements may be needed to further improve the eight-item short version.