Inhibition of Intermediate-Term Memory Following Passive Avoidance Training in Neonate Chicks by a Presynaptic Cholinergic Blocker

The effects of a specific presynaptic cholinergic antagonist, toosendanin, on memory formation following a passive avoidance training experience in day-old chicks was investigated. Bilateral injection of toosendanin into the neostriatal/hyperstriatal region of the chick forebrain produced memory impairment in a dose-dependent manner. Retention deficits were apparent from 20 min following training in chicks treated with toosendanin, regardless of the injection time relative to training. Chicks that received injections of the drug at corresponding times prior to retention tests showed normal retention levels, suggesting that toosendanin has no effect on performance and memory retrieval. These results indicate an involvement of cholinergic transmission during an early stage of memory formation.     

Leader-Member Exchange and Transformational Leadership: An Empirical Examination of Innovative Behaviors in Leader-Member Dyads

This paper evoked leader-member exchange (LMX) and transformational leadership theories to explain innovative behavior in leader-member dyads. Data from 225 leader-member dyads in a Fortune 500 manufacturing plant found exchange quality to be positively related to follower autonomy, leader support of followers, and follower commitment to the organization. Further, followers who were supported by their leaders and who were committed to the organization were more likely to be innovative. Also, exchange quality was directly related to innovative behaviors. Contrary to expectations, transformational leadership was negatively related to innovative behaviors of followers.     

Differential effects of oral reading to improve comprehension with severe learning disabled and educable mentally handicapped students

The purpose of this study was to evaluate the effectiveness of oral reading as a teaching technique for improving reading comprehension of 11 Educable Mentally Handicapped or Severe Learning Disabled adolescents. Students were tested on their ability to answer comprehension questions from a short factual article. Comprehension improved following the oral reading for students with a reading grade equivalent of less than 5.5 (measured from the Wide Range Achievement Test) but not for those students having a grade equivalent of greater than 5.5. This association was statistically significant (p = less than .01). Oral reading appeared to improve comprehension among the poorer readers but not for readers with moderately high ability.     

Gastric pathology and feeding deficits induced by hypothalamic damage in rats: effects of lesion type, size, and placement.

Three doses each of cathodal or anodal direct current were delivered to coagulate lateral hypothalamic tissue bilaterally in rats. Increases in hypothalamic tissue damage were associated with more instances of aphagia, greater amounts of glandular, but not rumenal, gastric pathology, and greater weight loss. Both anodal and cathodal lesions produced aphagia and similar amounts of gastric pathology, but anodal lesions also appeared to facilitate weight loss independently of the tissue damage. Extensive chromatolysis surrounding anodal lesion cavities may be importantly related to the postoperative effects. In additional experiments, anodal electrolytic lesions or cortical suction ablations were used to vary the location of neural damage. Fedding deficits and gastric pathology resulted from the destruction of several brain areas. In particular, eating of dry food in the presence of high gastric pathology was observed in rats with lesions ventral and medial to an area in the dorsolateral hypothalamus that was associated with aphagia. When aphagia was accompained by severe gastric pathology, the brain lesions typically encroached extensively on more ventromedial areas. Moreover, aphagia sometimes was observed with only negligible gastric pathology. It is suggested that gastric pathology is not primary to the expression of the aphagia that follows lateral hypothalamic damage.     

Preliminary findings with a new Vietnamese Stroop test.

Stroop performance was compared in primary Vietnamese- vs English-speaking individuals (age range 19-68 years), currently living in the USA. A modified Vietnamese Stroop task mimicked word, color, and interference effects of an English-language Stroop test. Stroop performance (items correctly completed and interference "cost") did not differ significantly between 30 Vietnamese Americans whose first language was Vietnamese (M age 34.3 yr.) vs 30 American-born individuals whose first language was English (M age 31.2 yr.). Expected performance decrements with aging were observed in English-language Stroop performance but not in Vietnamese-language Stroop performance, which instead exhibited a trend towards the opposite pattern. Unexpected group differences associated with age in Stroop performance may reflect subtle differences in task demands, not evident in simple category performance scores, or alternatively, cultural or neuropsychological differences in the study groups.     

Scale of attentional focus in visual search

The effects of the spatial scale of attention on feature and conjunction search were examined in two experiments. Adult participants in three age groups—young, young-old, and old-old—were given precues of varying validity and precision in indicating the location of a target letter subsequently presented in a visual array. Systematic decreases in the size of a valid precue (toward the size of the target) progressively facilitated both feature and conjunction search, with a greater benefit accruing to conjunction search. Age-related slowing in conjunction search was mitigated by precise (small and valid) precues, presumably because they reduced the need for participants in the young-old group to focus and to shift attention. Nevertheless, this benefit was reduced in the old-old group. The effects of valid location precue size varied with cue-target stimulus onset asynchrony (SOA) in a manner that interacted with search difficulty: Effects of cue size developed more rapidly in feature search but more slowly in conjunction search. Finally, when precues were invalid for target location, search was faster with larger sized precues. Thus, in both easy feature search and hard conjunction search, the scale of visuospatial attention modulates the speed of visual search. Furthermore, when the SOA is sufficiently long for cue effects to develop, the ability to dynamically adjust the scale of visuospatial attention appears to decline in advanced age. These results go beyond current models in suggesting that visuospatial attention possesses two dynamic properties—shifting in space and varying in scale—that are deployed independently, depending on task demands.