Acquisition of discrimination learning of patterns identical in configuration in macaques (Macaca mulatta and M. fuscata)

The acquisition of discrimination of five pairs of pattern cues in a Wisconsin General Testing Apparatus by 223 naive macaque monkeys was compared. The pairs of discriminanda were identical in configuration but varied slightly in either the size of the cue or the size of the background plaque; thus, the degree of separation of the cue from the fringe of the plaque, the response site, was slightly different for each pair of discriminanda. These small differences in cue-response separation had marked effects on the rate of acquisition of the discriminations. Even an increment of separation as small as 0.5 cm resulted in a remarkable retardation of the acquisition. This retardation was due entirely to prolonged performance at the chance level, and not to a slow rate of improvement from the chance to a criterion level. The finding indicates that the difficulty in the acquisition learning on pattern tasks depends largely on the difficulty of attending to the pattern cues at small cue-response separations.     

A System for Relational Reasoning in Human Prefrontal Cortex

The integration of multiple relations between mental representations is critical for higher level cognition. For both deductive- and inductive-reasoning tasks, patients with prefrontal damage exhibited a selective and catastrophic deficit in the integration of relations, whereas patients with anterior temporal lobe damage, matched for overall IQ but with intact prefrontal cortex, exhibited normal relational integration. In contrast, prefrontal patients performed more accurately than temporal patients on tests of both episodic memory and semantic knowledge. These double dissociations suggest that integration of relations is a specific source of cognitive complexity for which intact prefrontal cortex is essential. The integration of relations may be the fundamental common factor linking the diverse abilities that depend on prefrontal function, such as planning, problem solving, and fluid intelligence.     

Scientific misconduct: Present problems and future trends

Substantial progress in handling scientific misconduct cases has been made since the first cases were investigated by the NIH Office of Scientific Integrity in 1989. The successor Office of Research Integrity (ORI) has simultaneously reduced the backlog of cases and increased the professionalism with which they are handled. However, a spate of lawsuits against universities, particularly those brought under the federal False Claims Act, threatens to undermine the ORI by encouraging use of the courts as an alternate route for resolving claims of research misconduct. Next steps should include establishing a government-wide definition of scientific misconduct, providing immunity from lawsuits for institutions that follow proper procedures in investigating charges of scientific misconduct, and participating in the development of international guidelines for maintaining scientific integrity. An earlier version of this paper was presented at the symposium entitled “Misconduct in Science: A Decade of Progress or Merely Years of Controversy” held during the Annual Meeting of the American Association for the Advancement of Science, Philadelphia, Pennsylvania, 13 February, 1998.     

Brain and cognitive-behavioural development after asphyxia at term birth

Perinatal asphyxia occurs in approximately 1-6 per 1000 live full-term births. Different patterns of brain damage can result, though the relation of these patterns to long-term cognitive-behavioural outcome remains under investigation. The hippocampus is one brain region that can be damaged (typically not in isolation), and this site of damage has been implicated in two different long-term outcomes, cognitive memory impairment and the psychiatric disorder schizophrenia. Factors in addition to the acute episode of asphyxia likely contribute to these specific outcomes, making prediction difficult. Future studies that better document long-term cognitive-behavioural outcome, quantitatively identify patterns of brain injury over development and consider additional variables that may modulate the impact of asphyxia on cognitive and behavioural function will forward the goals of predicting long-term outcome and understanding the mechanisms by which it unfolds.     

The effects of physostigmine and scopolamine on recognition memory in monkeys

The visual recognition of rhesus monkeys was evaluated by means of a delayed nonmatching-to-sample task with trial-unique objects. Each daily session consisted of two lists of 20 objects each, which untreated animals were able to recognize at approximately 75% accuracy. When they were performing at this level reliably, doses of physostigmine (0.32, 1.0, 3.2, 10.0, 32.0, 56.0 micrograms/kg), scopolamine (1.0, 3.2, 5.6, 10.0, 17.8, 32.0 micrograms/kg), or saline were administered 20 min prior to the session. Physostigmine and scopolamine produced dose-related increases and decreases, respectively, in the number of objects correctly remembered. The systematic changes in performance support the view that cholinergic mechanisms contribute to recognition memory and suggest that tasks with trial-unique objects may be particularly useful for studying the mnemonic effects of cholinergic drugs.