Mechanisms underlying working memory for novel information

In this Opinion article we describe a theory that the brain mechanisms underlying working memory for novel information include a buffer in parahippocampal cortices. Computational modeling indicates that mechanisms for maintaining novel information in working memory could differ from mechanisms for maintaining familiar information. Electrophysiological data suggest that the buffer for novel information depends on acetylcholine. Acetylcholine activates single-cell mechanisms that underlie persistent spiking of neurons in the absence of synaptic transmission, allowing maintenance of information without prior synaptic modification. fMRI studies and lesion studies suggest that parahippocampal regions mediate working memory for novel stimuli, and the effects of cholinergic blockade impair this function. These intrinsic mechanisms in parahippocampal cortices provide an important alternative to theories of working memory based on recurrent synaptic excitation.     

Same-sex couple perceptions of family support: a consensual qualitative study

Few studies have examined the family context in which same-sex couples negotiate their lives and relationships. Consensual qualitative research methods (Hill, Thompson, & Williams, 1997) were used to analyze 14 same-sex couples' conversations about family support. Couples perceived that their families are positively supportive, non-supportive, or ambivalent in their support. These perceptions led to positive or negative emotional reactions in the couple members and to specific coping. The majority of couples perceived that family support (or lack of support) had an effect on the quality of their couple relationship. No general or typical response strategies to lack of family of origin support emerged, suggesting a lack of models or norms for same-sex couples. The implications for psychotherapeutic interventions with same-sex couples are discussed.     

Attentional resource and processing speed limitations during sentence processing in Parkinson's disease

Several studies have suggested that patients with Parkinson's disease (PD) have sentence comprehension difficulty in part because of their limited executive resources. However, these assessments confound the executive resources contributing to sentence comprehension with the resources needed for task performance. In the present study, we used a word detection technique that minimizes task demands in order to evaluate attentional and processing speed resources during the comprehension of simple sentences without subordinate clauses and sentences containing subject-relative and object-relative center-embedded subordinate clauses. We found that PD patients have poor sensitivity to phonetic errors embedded in unbound grammatical morphemes, regardless of the clausal structure of the sentence, suggesting difficulty attending to grammatical morphemes. We also found that PD patients are significantly slowed in their sensitivity to phonetic errors in content words embedded in object-relative center-embedded sentences. Slowed sensitivity to content words in object-relative sentences was correlated with timed executive measures of planning. On a traditional measure of comprehension, these PD patients were impaired for sentences containing object-relative center-embedded clauses compared to sentences with subject-relative center-embedded clauses, and comprehension of object-relative sentences was correlated with executive measures. Our findings are consistent with the claim that limited executive resources for strategic attention and processing speed contribute to the sentence comprehension difficulties of PD patients.     

Medical Students' Perceptions of and Willingness to Treat Patients Who Are HIV Infected1

The purpose of this study is to examine the independent and joint influences of a patient's mode of acquisition of illness (blood transfusion vs. multiple sexual partners), attributions of responsibility (self-blame vs. chance blame), and sexual orientation (homosexual vs. heterosexual) on female and male medical students' attitudes toward and willingness to treat a patient who is HIV infected. One hundred nineteen 1st through internship-year medical students were randomly assigned to read and respond to case vignettes. Greater consistency between attribution of blame and mode of acquisition was related to more positive perceptions. Furthermore, the patient's sexual orientation influenced the providers' willingness to offer treatment, particularly for male medical students. Implications concerning health practices and medical education are considered.     

Evidence for frames of reference based on pursuit eye movements

Lighted points that moved as if located on the rim of a rolling wheel were displayed to subjects whose task was to describe the pattern they perceived. The perceived patterns could be classified into one of four categories ranging from cycloidal to circular motion. Pursuit eye movements were controlled by having subjects track a fixation point that moved in the direction of the rolling wheel on a path just above the wheel’s rim. With respect to the translatory velocity of the rolling wheel, the velocity of the fixation point was 100%, 67%, 33%, or 0% (i.e., stationary). The patterns traced out by the points on the wheel were perceived to become increasingly circular as pursuit eye movements more closely matched the translatory speed of the rolling wheel. This is taken to support Stoper’s hypothesis that pursuit eye movements can establish a frame of reference for motion analysis.     

Interal locus of control as a value

Internal and external subjects, who previously filled out Rotter's (1966) I-E scale, were asked to score the I-E scale of “another student”. Subjects were exposed to “an other's” score of either 0, 5, 10, 16, or 23, and were asked to rate themselves and the “other” on an evaluative questionnaire. It was predicted that ratings of the “other” would increase in positivity to the extent the “other” scored as an internal. A reverse direction was predicted for an index of negative evaluations. The predictions were confirmed. The results suggest that internal locus of control is a societal value. The findings did not support either Hannah's (1973) hypothesis that internals are more responsive to a need for social approval, or Byrne's (1969) similarity hypothesis.     

The time course of automatic lexical access and aging

This study addresses the issue of cognitive slowing in the elderly by examining the time course of automatic lexical access. College-aged subjects typically show a brief rise time (300-500 msec) for lexical access. In the present study, we examine whether there are changes in rapid, automatized access routines with age. Elderly and college-aged subjects performed a lexical decision task wherein semantically related words embedded in a continuous list were presented one at a time with a varying (300-1500 msec) inter-word interval. The use of a continuous list, a repeated word, and a very short inter-stimulus interval allowed automatic lexical access to be straightforwardly examined. The elderly subjects showed an onset of automatic lexical access that was similar in time frame to that for college-age subjects. These findings suggest that wherever the locus of age-related slowing may be, it is not in the early, language-specific processing devices that mediate lexical access.     

Blinks as an index of cognitive activity during reading

Horizontal and vertical EOG recordings of eye movements were analyzed to determine the spatial and temporal distribution of blinks and the patterns of eye movements (saccades and fixation pauses) exhibited by six subjects during the reading of stories presented in two formats (on paper and on a VDT). The frequency and placement of blinks was not affected by the presentation condition. Blinks were determined to be non-randomly distributed during reading. Significantly more blinks (36%) occurred in conjunction with saccades than the proportion of time consumed by saccades (12%) would predict. Significantly more blinks (36%) occurred in the vicinity of line change saccades, which accounts for 15% of reading time, and with fixation pauses associated with regressions (42%), which accounts for 26% of reading time, than with fixation pauses during normal reading (22%), which accounts for 60% of reading time. The results of the study suggest that blink behavior during reading is under perceptual and cognitive control.