David L. Macmillan

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The capacity to associate stimuli underlies many cognitive abilities, including recognition, in humans and other animals. Vertebrates process different categories of information separately and then reassemble the distilled information for unique identification, storage and recall. Invertebrates have fewer neural networks and fewer neural processing options(More)
Touch is a principal sense in all animals. It is potentially important in species of freshwater crayfish that encounter murky waters or are nocturnal. Little is known about how tactile (touch) stimuli affect exploratory behaviour under these conditions. We placed animals in different tactile situations at the start of an exploration in a dark arena and(More)
The normal, unrestrained, forward walking of the lobster was studied with a closed-circuit television system and a video-tape recorder. A frame-by-frame analysis was undertaken and measurements made of unilateral stepping sequences, contralateral and ipsilateral phase relations between pairs of legs, the movements at the leg joints primarily involved in(More)
Many crayfish species inhabit murky waters or have a crepuscular lifestyle, which forces them to rely on chemical and mechanical information rather than visual input. Information on how they use one form of mechanical information-tactile cues-to explore their local environment is limited. We observed the exploratory behavior of the crayfish Cherax(More)
Periods of isolation during which animals have no social contact are common in the design of behavioral experiments. They are used, for example, to test memory and recognition responses, or to ensure a baseline condition before experimental manipulations commence. We investigated the effect of isolation periods on the aggressive behavior of matched pairs of(More)
How does an animal adjust its motor output to generate the same movement despite changing environmental load? The neuromuscular system that controls postural movements of the crayfish abdomen has attracted interest as a system well-suited for the study of load compensation. The motor neurones and superficial muscles that control the movement of each(More)
SUMMARY 1. High-speed cinematography of the escape behaviour of freely-moving crayfish showed that the thoracic and abdominal appendages exhibit stereotyped movements in giant axon-mediated tail flips and in non-giant flips. Three distinct classes of non-giant tail flips were recognized in this study: linear, pitching and twisting flips. 2. In medial giant(More)
We examined the escape behavior of larvae and postlarvae of the American lobster (Homarus americanus) and of adult immature (stage ADI) crayfish (Cherax destructor). Responses to standardized water jet stimuli delivered through a pipette were observed and analyzed. Lobster larvae did not respond to stimuli within 60 ms, indicating that they do not have(More)
The serial homology of arthropods, together with our ability to identify individual neurons from segment to segment, and from animal to animal, provides opportunities for studying the changes wrought by natural selection on specific neural elements when functional requirements change in different parts of the trunk. Using this concept as a guide, we studied(More)