870 research outputs found
Predecessor Features
Any reinforcement learning system must be able to identify which past events
contributed to observed outcomes, a problem known as credit assignment. A
common solution to this problem is to use an eligibility trace to assign credit
to recency-weighted set of experienced events. However, in many realistic
tasks, the set of recently experienced events are only one of the many possible
action events that could have preceded the current outcome. This suggests that
reinforcement learning can be made more efficient by allowing credit assignment
to any viable preceding state, rather than only those most recently
experienced. Accordingly, we examine ``Predecessor Features'', the fully
bootstrapped version of van Hasselt's ``Expected Trace'', an algorithm that
achieves this richer form of credit assignment. By maintaining a representation
that approximates the expected sum of past occupancies, this algorithm allows
temporal difference (TD) errors to be propagated accurately to a larger number
of predecessor states than conventional methods, greatly improving learning
speed. The algorithm can also be naturally extended from tabular state
representation to feature representations allowing for increased performance on
a wide range of environments. We demonstrate several use cases for Predecessor
Features and compare its performance with other approaches.Comment: Accepted to RLDM 202
Effect of Aqueous and Ethanolic Extracts of Tribulus terrestris, Phoenix dactylifera and Nasturtium officinale Mixture on Some Reproductive Parameters in Male Mice
The present investigation was conducted to evaluate the effect of the crude extracts mixture of three plants (Tribulus terrestris, Phoenix dactylifera and Nasturtium officinale) on semen quality,sex hormones and reproductive performance of mature male mice. A group of 25 male mice given 150mg/kg/day of the powder of the plants mixture with the food for four weeks and another three groups of 25 animals each given intraperitoneal injection from each of the aqueous and ethanolic extracts with a doses 75, 150, and 300mg/kg/day for two weeks. A remarkable increase in sperm concentration and motility with a decreased abnormal morphology was obtained in the experimental groups. A significant increase in hormones level were recognized in most groups. The results of mating untreated females with treated males of the four experimental groups revealed a decreased gestation period and an increased litter size. The results showed a dose dependent pattern of activity and the effect of the extracts were enhanced with increasing the dose level. The ethanolic extract being the more effective extract in all parameters
Influence of Peri-duodenal Non-constrictive Cuff on the Body Weight of Rats
Background
Weight loss has been found to improve or re-
solve cardiovascular comorbidities. There is a significant need
for reversible device approaches to weight loss.
Methods
Non-constrictive cuff (NCC) is made of implantable
silicone rubber with an internal diameter greater than the
duodenum. Ten or 11 NCC were individually mounted along
the duodenum from the pyloric sphincter toward the distal
duodenum to cover ~22 mm in the length. Twelve Wistar rats
were implanted with NCC, and six served as sham, and both
groups were observed over 4 months. Six rats with implant
had their NCC removed and were observed for additional
4weeks.
Results
The food intake decreased from 40.1 to 28.1 g/day
after 4 months of NCC implant. The body weight gain
decreased from 1.76 to 0.46 g/day after 4 months of NCC
implant. The fasting glucose decreased from 87.7 to 75.3 mg/
dl at terminal day. The duodenal muscle layer covered by the
NCC increased from 0.133 to 0.334 mm. After 4 weeks of
NCC removal, the food intake, body weight gain, and fasting
glucose recovered to 36.2, 2.51 g/day, and 83.9 mg/dl. The
duodenal muscle layer covered by the NCC decreased to
0.217 mm.
Conclusion
The NCC implant placed on the proximal duode-
num is safe in rats for a 4-month period. The efficacy of the
NCC implant is significant for decrease in food intake, body
weight gain, and fasting glucose in a normal rat model. The
removal of NCC implant confirmed a cause-effect relation
with food intake and hence body weight
Emergence and reconfiguration of modular structure for synaptic neural networks during continual familiarity detection
While advances in artificial intelligence and neuroscience have enabled the
emergence of neural networks capable of learning a wide variety of tasks, our
understanding of the temporal dynamics of these networks remains limited. Here,
we study the temporal dynamics during learning of Hebbian Feedforward (HebbFF)
neural networks in tasks of continual familiarity detection. Drawing
inspiration from the field of network neuroscience, we examine the network's
dynamic reconfiguration, focusing on how network modules evolve throughout
learning. Through a comprehensive assessment involving metrics like network
accuracy, modular flexibility, and distribution entropy across diverse learning
modes, our approach reveals various previously unknown patterns of network
reconfiguration. In particular, we find that the emergence of network
modularity is a salient predictor of performance, and that modularization
strengthens with increasing flexibility throughout learning. These insights not
only elucidate the nuanced interplay of network modularity, accuracy, and
learning dynamics but also bridge our understanding of learning in artificial
and biological realms
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