2,419 research outputs found
Multi-alternative decision-making with non-stationary inputs
One of the most widely implemented models for multialternative
decision-making is the multihypothesis sequential
probability ratio test (MSPRT). It is asymptotically optimal,
straightforward to implement, and has found application in
modelling biological decision-making. However, the MSPRT
is limited in application to discrete (‘trial-based’), non-timevarying
scenarios. By contrast, real world situations will
be continuous and entail stimulus non-stationarity. In these
circumstances, decision-making mechanisms (like the MSPRT)
which work by accumulating evidence, must be able to discard
outdated evidence which becomes progressively irrelevant. To
address this issue, we introduce a new decision mechanism
by augmenting the MSPRT with a rectangular integration
window and a transparent decision boundary. This allows
selection and de-selection of options as their evidence changes
dynamically. Performance was enhanced by adapting the
window size to problem difficulty. Further, we present an
alternative windowing method which exponentially decays
evidence and does not significantly degrade performance,
while greatly reducing the memory resources necessary. The
methods presented have proven successful at allowing for the
MSPRT algorithm to function in a non-stationary environment
Is the short-latency dopamine response too short to signal reward error?
Unexpected stimuli that are behaviourally significant have the capacity to elicit a short-latency, short-duration burst of firing in mesencephalic dopaminergic neurones. An influential interpretation of the experimental data that characterize this response proposes that dopaminergic neurones have a crucial role in reinforcement learning because they signal error in the prediction of future reward. In this article we propose a different functional role for this ‘short-latency dopamine response’ in the mechanisms that underlie associative learning. We suggest that the initial burst of dopaminergic-neurone firing could represent an essential component in the process of switching attentional and behavioural selections to unexpected, behaviourally important stimuli. This switching response could be a crucial prerequisite for associative learning and might be part of a general short-latency response that is mediated by catecholamines and prepares the organism for an appropriate reaction to biologically significant events.
Any act which in a given situation produces satisfaction becomes associated with that situation so that when the situation recurs the act is more likely than before to recur also. E.L. Thorndike (1911)
The basal ganglia: A vertebrate solution to the selection problem?
A selection problem arises whenever two or more competing systems seek simultaneous access
to a restricted resource. Consideration of several selection architectures suggests there are significant
advantages for systems which incorporate a central switching mechanism. We propose that the vertebrate
basal ganglia have evolved as a centralized selection device, specialized to resolve conflicts over access to
limited motor and cognitive resources. Analysis of basal ganglia functional architecture and its position
within a wider anatomical framework suggests it can satisfy many of the requirements expected of an
efficient selection mechanism
TELLUS: A combined surface temperature, soil moisture and evaporation mapping approach
There are no author-identified significant results in this report
Reply to Bone mineral density in young adult survivors of acute lymphoblastic leukemia
No abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/64309/1/24456_ftp.pd
Agent architecture for adaptive behaviours in autonomous driving
Evolution has endowed animals with outstanding adaptive behaviours which are grounded in the organization of their sensorimotor system. This paper uses inspiration from these principles of organization in the design of an artificial agent for autonomous driving. After distilling the relevant principles from biology, their functional role in the implementation of an artificial system are explained. The resulting Agent, developed in an EU H2020 Research and Innovation Action, is used to concretely demonstrate the emergence of adaptive behaviour with a significant level of autonomy. Guidelines to adapt the same principled organization of the sensorimotor system to other agents for driving are also obtained. The demonstration of the system abilities is given with example scenarios and open access simulation tools. Prospective developments concerning learning via mental imagery are finally discussed
A Model for an Angular Velocity-Tuned Motion Detector Accounting for Deviations in the Corridor-Centering Response of the Bee
We present a novel neurally based model for estimating angular velocity (AV) in the bee brain, capable of quantitatively reproducing experimental observations of visual odometry and corridor-centering in free-flying honeybees, including previously unaccounted for manipulations of behaviour. The model is fitted using electrophysiological data, and tested using behavioural data. Based on our model we suggest that the AV response can be considered as an evolutionary extension to the optomotor response. The detector is tested behaviourally in silico with the corridor-centering paradigm, where bees navigate down a corridor with gratings (square wave or sinusoidal) on the walls. When combined with an existing flight control algorithm the detector reproduces the invariance of the average flight path to the spatial frequency and contrast of the gratings, including deviations from perfect centering behaviour as found in the real bee's behaviour. In addition, the summed response of the detector to a unit distance movement along the corridor is constant for a large range of grating spatial frequencies, demonstrating that the detector can be used as a visual odometer
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