Spontaneous recovery of excitation and inhibition.

In two conditioned suppression experiments with rats as subjects, the authors examined two classes of accounts of spontaneous recovery of excitation and inhibition. One view suggests that spontaneous recovery occurs due to greater temporal instability of inhibitory associations, whereas the other posits that spontaneous recovery occurs due to greater temporal instability of second-learned associations. These accounts diverge in predictions concerning spontaneous recovery when the first-learned association is inhibitory and the second-learned association is excitatory.

Overshadowing and CS duration: counteraction and a reexamination of the role of within-compound associations in cue competition.

In the present experiments, we examined the role of within-compound associations in the interaction of the overshadowing procedure with conditioned stimulus (CS) duration, using a conditioned suppression procedure with rats. In Experiment 1, we found that, with elemental reinforced training, conditioned suppression to the target stimulus decreased as CS duration increased (i.e.

Overexpectation and trial massing.

Three experiments were conducted to examine the interaction of overexpectation treatment and trial massing using a Pavlovian fear conditioning procedure with rats. In first-order conditioning, Experiment 1 found the overexpectation effect (i.e.

Fibrogenesis imperfecta ossium (Baker's disease): a case studied at autopsy.

A man aged 40 years showed radiographic changes in the form of generalized increased bone density and patchy rarefaction. Urinary calcium was increased and serum alkaline phosphatase was elevated; serum calcium and phosphate levels were normal. Multiple fractures developed.

Fibrous dysplasia of bone: case report with autopsy study 80 years after the original clinical recognition of the bone lesions.

We present a report of the histological features of the bone lesions in a case of polyostotic fibrous dysplasia studied at autopsy in a patient aged 88 years. While much of the fibrous tissue of the lesions contained the trabeculae of non-lamellar bone that are a feature of fibrous dysplasia in young patients, other parts of the lesions showed evidence of osteoclastic remodelling of bone trabeculae, and even of the replacement of some of these structures by mature lamellar bone.