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Biomedical subjects

D G Elmes

Publications and source records attributed to D G Elmes.

6 recordsLinked to original sources
PubMed1999

A computer-controlled olfactometer for fMRI and electrophysiological studies of olfaction.

A design for an inexpensive and reliable olfactometer is presented. The design has several advantages for fMRI and electrophysiology investigators. These advantages include relatively rapid odorant rise times, computer control, multiple odor administration, and no ferrous materials near the subjects. In addition, the device is contamination resistant, and, because the air is neither warmed nor humidified, it is unlikely to become an incubator for bacteria. The olfactometer is constructed of off-the-shelf chromatography parts that require little modification.

Computers↗
PubMed1998

Chemosensory alteration of information processing.

Previous research has found both facilitation and interference when odors are administered during the performance of cognitive tasks. The present research was designed to investigate the possibility that odors might differentially effect different varieties of cognitive tasks. Twelve subjects performed matched verbal, numeric, and spatial tasks as event-related potentials were measured. Odors and tones were introduced as subjects completed the tasks in a paradigm optimized to produce disruption of performance. Results indicated that P300 amplitude to the task stimuli depended upon the type of task and the modality of the distractor. P300 amplitude was relatively consistent across tasks for the tone distractor. During the olfactory distractor, P300 amplitude was greater for the symbolic stimuli (verbal and numeric) and lower for the spatial. Reaction times to the various tasks did not differ as a function of the modality of the distractor.

Adolescent↗
PubMed1998

Is there an inner nose?

Although behavioral and neuropsychological data regarding the existence of images for odors are inconclusive, reconsideration of earlier EEG work provides reasonably clear evidence for an inner nose. However, further EEG studies and neuroimaging data seem essential for conclusive demonstration of an inner nose.

Electroencephalography↗
PubMed1988

Interference in spatial memory.

Four experiments examined interference in human spatial memory. The first two tested for retroactive interference by varying the similarity between the interpolated task and the task that was learned originally. Retroactive interference was observed during relearning of a radial stylus maze and during relearning of the locations of pairs of playing cards in a concentration game. In the third and fourth experiments, proactive interference was tested during the relearning of the locations of pairs in a concentration game. Some proactive interference was observed when the number of proactive games was varied (Experiment 3), and substantial proactive interference was found when the similarity between the proactive and target tasks was the independent variable (Experiment 4). Although extensive evidence indicates that spatial memory differs from other types of memory, spatial memory is subject to interference effects, as are verbal memory, motor memory, visual discriminative memory in animals, and animal spatial memory.

Adult↗
PubMed1982

Role of retroactive interference in the spatial memory of normal rats and rats with hippocampal lesions.

The importance of retroactive interference (RI) in memory for spatial locations was studied by using a 12-arm radial maze and a standard RI paradigm. Animals in the RI condition first learned to choose 4 of the 12 arms, followed by training to a second set of 4 arms. In the control condition for interference, rats learned the first set of arms but were not trained to approach the second set. Thereafter, animals in each interference condition were assigned to groups (hippocampal, cortical control, unoperated control), the operations were carried out, and then all animals were tested for retention of the set of arms learned first. Contrary to predictions of the cognitive map theory, O'Keefe & Nadel, 1978), RI was found in control animals. The severe memory deficit found in hippocampals was not influenced by the interference variable. In addition to impaired performance early in relearning, rats with hippocampal lesions continued to make many errors throughout the 10 wk of testing, including choices to unbaited arms and repeated entries into baited arms. However, hippocampals eventually learned not to reenter unbaited arms. These data indicate a deficit in the selection and utilization of sets of responses and are interpreted as implicating the hippocampus in retrieval processes.

Animals↗