Biomedical subjects

J G Boal

Publications and source records attributed to J G Boal.

4 recordsLinked to original sources

PubMed2000

The effect of early experience on learning and memory in cuttlefish.

The effect of early experience on the growth and ontogeny of memory in cuttlefish (Sepia officinalis) was studied using an associative learning protocol. Five groups of cuttlefish were reared in different conditions (standard conditions, SC; impoverished conditions, IC; enriched conditions, EC; impoverished then enriched conditions, I/EC; enriched then impoverished conditions, E/IC) from birth to the 3rd month of postembryonic life. Acquisition and retention of the learning task were assessed at 1 and 3 months. Growth was slower and maturation of memory abilities occurred later in cuttlefish from Group IC than in cuttlefish from Group EC, with the maturation rate of memory in cuttlefish from Group SC intermediate between these two groups. Retention performances of cuttlefish from Groups I/EC and E/IC indicated that the environment of rearing during the 2nd and/or 3rd months of life was crucial for the development of memory.

Age Factors↗

PubMed2000

Cuttlefish use polarization sensitivity in predation on silvery fish.

Cephalopods are sensitive to the linear polarization characteristics of light. To examine if this polarization sensitivity plays a role in the predatory behavior of cuttlefish, we examined the preference of Sepia officinalis when presented with fish whose polarization reflection was greatly reduced versus fish whose polarization reflection was not affected. Cuttlefish preyed preferably on fish with normal polarization reflection over fish that did not reflect linearly polarized light (n = 24, chi 2 = 17.3, P < 0.0001), implying that polarization sensitivity is used during predation. We suggest that polarization vision is used to break the countershading camouflage of light-reflecting silvery fish.

Animals↗

PubMed2000

Experimental evidence for spatial learning on octopuses (octopus bimaculoides).

Octopuses forage far from temporary home dens to which they return for shelter. Spatial tasks may assess learning. Octopuses (Octopus bimaculoides) were placed in a novel arena, and their movements were tracked for 72 hr. Movements around the arena decreased across time, consistent with exploratory learning. Next, octopuses were given 23 hr to move around an arena; after a 24-hr delay, their memory of a burrow location was tested. Most remembered the location of the open burrow, demonstrating learning in 1 day. Finally, octopuses were trained to locate a single open escape burrow among 6 possible locations. Retention was tested after a week and was immediately followed by reversal training (location rotated 180 degrees ). Octopuses learned the original location of the burrow, remembering it for a week. Path lengths increased significantly after reversal, gradually improving and showing relearning. Octopuses show exploratory behavior, learning, and retention of spatial information.

Animals↗

PubMed1996

A review of simultaneous visual discrimination as a method of training octopuses.

I have presented a review and critique of the procedures employed in simultaneous discrimination training experiments using octopuses as subjects. Procedural variables were analyzed statistically for their influence on experimental outcome. The variables most significantly associated with successful discriminations included use of a specific start location for subjects, shock as negative reinforcement, fewer trials per session, more sessions per day, and discriminations based on stimulus brightness. No experiment controlled all potential sources of inadvertent cues, and subjects' performances appeared to be sensitive to exact procedural details. The most common practice diminishing evidence for learning involved reward that coincided with the subject's pre-existing preferences. I found no evidence that sub-optimal experimental designs biased experimental outcomes in any significant and systematic way. Although there is sufficient reason for rejecting results of published simultaneous discrimination training experiments, careful conclusive experiments remain to be performed.

Animals↗