Structural Stability within the Lateral Cerebellar Nucleus of the Rat Following Complex Motor Learning

Complex motor learning, but not mere motor activity, has been previously shown to induce structural modifications within the cerebellar cortex. The present experiment examined whether similar changes occur within one of the primary output targets of the region of the cerebellar cortex in which these structural changes were described, the lateral cerebellar nucleus (LCN; dentate nucleus). Adult female rats were randomly allocated to one of three training conditions. Acrobatic condition (AC) rats were trained to complete a complex motor learning task consisting of a series of elevated obstacles while motor control (MC) condition animals were forced to traverse a flat obstacle-free runway equal in length to the AC task. Inactive condition (IC) animals received no motor training. Unbiased stereological techniques and electron microscopy were used to obtain estimates of synapse number and postsynaptic density (PSD) length within the LCN. Results showed that neither synapse number nor PSD length was significantly altered as a function of training condition. These results indicate that complex motor skill learning is associated with structural plasticity within the cerebellar cortex and with structural stability within the lateral cerebellar nucleus.     

Mapping symbols to response modalities: Interference effects on Stroop-like tasks

Attention, Perception, & Psychophysics - Response compatibility effects were assessed with a Stroop-like task which involved arrow and word stimuli. The subjects were required to respond to one...     

Disinhibition of return: Unnecessary and unlikely

Recently, from data obtained with a temporal order judgment (TOJ) task, Gibson and Egeth (1994) concluded that inhibition of return (IOR; a response time effect that reveals slower responding to targets at previously cued versus uncued locations) reflects impaired perceptual processing. By replotting their data, we demonstrate that the perception of temporal order is influenced only by the facilitatory effect of a cue at short stimulus onset asynchronies (SOAs) and is unaffected by IOR at long SO As. The target paper proposed that, when extra stimuli are presented at task-relevant locations (i.e., in the TOJ task), IOR is prevented by a hypothetical process that is known as disinhibition of return (DOR). We argue that the assumptions that IOR affects perceptual processing and that DOR exists are unnecessary, as a more parsimonious response-based interpretation of IOR is consistent with their data. Further, we summarize recent results and present new data that demonstrate that DOR is unlikely.     

A Feminist Analysis of Seventeen Magazine: Content Analysis from 1945 to 1995

This study is an extension of the contentanalysis conducted by K. Peirce [(1990) AFeminist Theoretical Perspective on the Socialization ofTeenage Girls Through Seventeen Magazine, SexRoles, Vol. 23, pp. 491-500]. Her study examined thecontent of Seventeen magazine for the years 1961, 1972,and 1985, and the impact of the feminist movement fromthe 1960s through the 1980s. The present study explored the content of Seventeen magazine in the years1945, 1955, 1965, 1975, 1985, and 1995 to determine ifthe articles that are presented have changed in responseto the feminist movement from the 1940s to the present day. These results would supportthe contention that there is a relationship between thecontent of Seventeen magazine, in terms of traditionalvs. feminist messages, and the women's movement. However, these changes are slight and still donot reflect the various roles of teenage girls.Implications for further research arediscussed.     

Relationship between vomiting and taste aversion learning in the ferret: studies with ionizing radiation, lithium chloride, and amphetamine.

The relationship between emesis and taste aversion learning was studied in ferrets (Mustela putorius furo) following exposure to ionizing radiation (50-200 cGy) or injection of lithium chloride (1.5-3.0 mEq/kg, ip). When 10% sucrose or 0.1% saccharin was used as the conditioned stimulus, neither unconditioned stimulus produced a taste aversion, even when vomiting was produced by the stimulus (Experiments 1 and 2). When a canned cat food was used as the conditioned stimulus, lithium chloride, but not ionizing radiation, produced a taste aversion (Experiment 3). Lithium chloride was effective in producing a conditioned taste aversion when administration of the toxin was delayed by up to 90 min following the ingestion of the canned cat food, indicating that the ferrets are capable of showing long-delay learning (Experiment 4). Experiment 5 examined the capacity of amphetamine, which is a qualitatively different stimulus than lithium chloride or ionizing radiation, to produce taste aversion learning in rats and cats as well as in ferrets. Injection of amphetamine (3 mg/kg, ip) produced a taste aversion in rats and cats but not in ferrets which required a higher dose (> 5 mg/kg). The results of these experiments are interpreted as indicating that, at least for the ferret, there is no necessary relationship between toxin-induced illness and the acquisition of a CTA and that gastrointestinal distress is not a sufficient condition for CTA learning.     

Reason in Teaching: Scheffler's Philosophy of Education “A Maximum of Vision and a Minimum of Mystery”

This discussion cocnentrates on the distinctive conception of teaching which Scheffler develops, one in which teachers recognize and obligation both to offer reasons for their beliefs and to accept questions and objections raised by their students; and it shows how this conception is rooted in ethical and epistemological considerations. It emerges that Scheffler has anticipated, and answered, various arguments currently being raised against an approach to teaching which values critical reflection by students, and that he has also succeeded in avoiding the excesses of neutralism and relativism. It is argued too that his work exemplifies his own belief in maintaining a linkage between philosophy and practical concerns