Biomedical subjects

Lewis Bott

Publications and source records attributed to Lewis Bott.

3 recordsLinked to original sources

PubMed2005

Modulations in the degree of synchronization during ongoing oscillatory activity in the human brain.

When a subject is asked to respond as quickly as possible to a stimulus he/she responds much faster if this stimulus is preceded by a warning cue. This cue enables the subject to anticipate the forthcoming stimulus, initiating neural processes subserving the future perception and processing of the target stimulus and the motor preparation of the associated response action. It has recently been suggested that neuronal activity before such an anticipated target stimulus could be associated with modulations in neuronal synchronization and oscillatory activity. Here we recorded electrical brain activity whilst subjects performed a choice reaction time task, in which one of the stimuli could be predicted with 90% certainty. We show that the prediction of a forthcoming stimulus was associated with an increase in gamma oscillations overlying occipital areas and a decrease in beta oscillations overlying sensorimotor cortex before the stimulus was presented. We suggest that these regionally specific modulations in oscillatory activity reflect the establishment of neural networks that are 'primed' for the future processing of the forthcoming predictable visual stimulus.

Adult↗

PubMed2004

Nonmonotonic extrapolation in function learning.

This article reports the results of an experiment addressing extrapolation in function learning, in particular the issue of whether participants can extrapolate in a nonmonotonic manner. Existing models of function learning, including the extrapolation association model of function learning (EXAM; E. L. DeLosh, J. R. Busemeyer, & M. A. McDaniel, 1997), cannot account for this type of extrapolation pattern. We present the results of an experiment in which participants were shown a series of paired stimulus-response magnitudes where the relationship between these 2 dimensions conformed to a cyclic function. Participants were shown to extrapolate from these training data in a nonmonotonic way, contrary to predictions from EXAM. A new model of function learning is presented, which predicts responses more accurately than EXAM.

Cognition↗

PubMed2004

Modeling the effects of prior knowledge on learning incongruent features of category members.

The authors conducted 3 experiments addressing the issue of how observations and multiple sources of prior knowledge are put together in category learning. In Experiments 1 and 2, learning was faster for critical features, which were predictable on the basis of prior knowledge, than for filler features, and this advantage increased as more observations were made. In addition, learning was fastest for incongruent features that could only be predicted using knowledge from other domains. In Experiment 3, presenting contradictory features that violated prior knowledge led to rote learning rather than use of prior knowledge. The results were simulated with the Baywatch model, which addresses how observations of category members lead to recruitment and selection of sources of prior knowledge.

Cognition↗