Establishment of the FMRFamide-immunoreactive olfacto-retinalis pathway during ontogeny of the rainbow trout (Oncorhynchus mykiss).

Migration of neurons is one of the mechanisms establishing normal central nervous system connectivity during ontogeny. Proper timing of axonal sprouting is relevant in the same context. In the present study, we used the immunoreactivity of the tetrapeptide FMRFamide (Phe-Met-Arg-Phe-NH2) to visualize the olfacto-retinalis projection during trout ontogeny. It starts to innervate the retina two to four weeks after hatching, in contrast to reports on salmon where it only appears after the fish are imprinted on their natal stream.

Learning of suckling odors by newborn rabbits declines with age and suckling experience.

After being nursed just once for 4-5 min by an artificially scented doe, newborn rabbits show the full pattern of nipple-search behavior when placed on a fur scented with the same odor as their mother. It was the aim of the present study to test whether such rapid learning is dependent on age. In Experiment 1 in which normally raised pups were nursed by a scented doe either on Days 1, 3 or 5, conditionability was found to decline markedly by postnatal Day 5. In Experiment 2 conditionability was maintained in pups deprived of suckling experience by bottle feeding from Days 1-4, but not in hand-raised pups allowed to search on a doe for 4 min daily without milk intake. Possible mechanisms underlying the decline in conditionability to suckling odors, as well as the potential functional significance of this early learning for immediate postnatal and later life are discussed.

Involvement of the olfactory bulb in consolidation processes associated with long-term memory in rats.

In a daily training paradigm, rats were trained to discriminate between spatially distinct electrical stimulations delivered to one olfactory bulb. Xylocaine injections were used to disrupt the olfactory bulb functioning in the region close to the electrode tips for 1 hr after training session. The treatment started either just after the session or 2 hr later. When compared with the performance of saline-injected rats, the performance of Xylocaine-injected rats was unimpaired except when the treatment started just after the daily session. In that case, acquisition of the task was slightly altered, and retention over a 5-day period was dramatically impaired. We therefore concluded that, within about 1 hr following training, the olfactory bulb is engaged in consolidation processes critical for long-term retention of learned olfactory cues.

Intracerebral chloroma complicating acute monocytic leukemia.

We present the case of a 21-year-old woman with an acute monocytic leukemia. When she was in complete hematological remission, she developed rapid progressive hemiparesis on the right caused by a left frontoparietal chloroma as confirmed by surgery and histological examination. Postoperatively, the patient recovered completely, and x-ray therapy followed. Since intracerebral myeloblastic tumors are extremely rare and since the neurosurgeon may be involved in treatment of these lesions, we are encouraged to present our findings.

Rapid odor conditioning in newborn rabbits: amnesic effect of hypothermia.

Rabbit pups are completely dependent on a maternal pheromone for the release of suckling behavior. However, if the mother is perfumed prior to nursing, pups will learn to respond to the novel odor with the characteristic nipple-search behavior in just one 3-4 min nursing episode. In a first investigation of the processes underlying this recently developed learning paradigm, time-dependent effects of hypothermia on retention of the task could be demonstrated. Thus pups whose whole body was cooled to a mouth temperature of 7 degrees C immediately after conditioning (n = 10) and tested 24 h later for 3 min on a perfumed fur did not differ significantly in their search response from naive, untreated controls (n = 10). In contrast, pups cooled 4 h after conditioning (n = 10) demonstrated clear retention of the learned response and searched as vigorously as conditioned but uncooled animals (n = 10). As pups of all groups demonstrated normal nipple-search behavior when tested on a lactating doe, the deficits associated with immediate cooling appear to have been specific to the learning task and time of treatment.

Importance of beta-noradrenergic receptors in the olfactory bulb of sheep for recognition of lambs.

Within a 4-hr period after parturition, the ewe learns the odor of her lamb that will allow later recognition of her offspring from alien lamb. This study investigated the importance of the activation of olfactory bulb (OB) beta-noradrenergic receptors in establishing this olfactory memory. Pregnant ewes (n = 24) were cannulated bilaterally in the OB. Two days before parturition, OB were perfused continuously (10 microliters/hr) with either a solution containing the selective beta-noradrenergic antagonist propranolol (10(-3) M) or vehicle. The results showed that, although 8 of 9 control ewes were still able to bond selectively to their lambs, only 7 of 15 propranolol-treated animals were able to bond (p = .04). These results suggest that activation of beta-noradrenergic receptors in the OB during the period surrounding parturition is required to establish olfactory recognition of the lamb.

A simple superimposition method for anatomical adjustments of CT and SPECT images.

A technique for superimposition of CT and single photon emission CT (SPECT) images is described. Regions of interest can be placed on SPECT images and projected to CT images. In this way, anatomical registration of regions of increased or decreased activity is possible. The equipment is easy to handle and available at low cost.