Lane Yoder
Lane Yoder
Institution:
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The networks proposed here show how neurons can be connected to form flip-flops, the basic building blocks in sequential logic systems. The novel neural flip-flops (NFFs) are explicit, dynamic, and can generate known phenomena of short-term memory. For each network design, all neurons, connections, ...
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The networks proposed here show how neurons can be connected to form flip-flops, the basic building blocks in sequential logic systems. The novel neural flip-flops (NFFs) are explicit, dynamic, and can generate known phenomena of short-term memory. For each network design, all neurons, connections, and types of synapses are shown explicitly. The neurons’ operation depends only on explicitly stated, minimal properties of excitement and inhibition. This operation is dynamic in the sense that the level of neuron activity is the only cellular change, making the NFFs’ operation consistent with the speed of most brain functions. Memory tests have shown that certain neurons fire continuously at a high frequency while information is held in short-term memory. These neurons exhibit seven characteristics associated with memory formation, retention, retrieval, termination, and errors. One of the neurons in each of the NFFs produces all of the characteristics. This neuron and a second neighboring neuron together predict eight unknown phenomena. These predictions can be tested by the same methods that led to the discovery of the first seven phenomena. NFFs, together with a decoder from a previous paper, suggest a resolution to the longstanding controversy of whether short-term memory depends on neurons firing persistently or in brief, coordinated bursts. Two novel NFFs are composed of two and four neurons. Their designs follow directly from a standard electronic flip-flop design by moving each negation symbol from one end of the connection to the other. This does not affect the logic of the network, but it changes the logic of each component to a logic function that can be implemented by a single neuron. This transformation is reversible and is apparently new to engineering as well as neuroscience.
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2 days ago
W. Penny
W. Penny
Institution:
Email:
This paper investigates models of working memory in which memory traces evolve according to stochastic attractor dynamics. These models have previously been shown to account for response-biases that are manifest across multiple trials of a visual working memory task. Here we adapt this approach by m...
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This paper investigates models of working memory in which memory traces evolve according to stochastic attractor dynamics. These models have previously been shown to account for response-biases that are manifest across multiple trials of a visual working memory task. Here we adapt this approach by making the stable fixed points correspond to the multiple items to be remembered within a single-trial, in accordance with standard dynamical perspectives of memory, and find evidence that this multi-item model can provide a better account of behavioural data from continuous-report tasks. Additionally, the multi-item model proposes a simple mechanism by which swap-errors arise: memory traces diffuse away from their initial state and are captured by the attractors of other items. Swap-error curves reveal the evolution of this process as a continuous function of time throughout the maintenance interval and can be inferred from experimental data. Consistent with previous findings, we find that empirical memory performance is not well characterised by a purely-diffusive process but rather by a stochastic process that also embodies error-correcting dynamics.
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2 days ago
Saman Hazany,
Saman Hazany
Institution: Keck School of Medicine of USC Radiology Department, Neuroradiology Division,
Email: samanh26@gmail.com
Brittany DeClouette
Brittany DeClouette
Institution: Keck School of Medicine of USC
Email: samanh26@gmail.com
In patients with Medial Temporal Lobe Epilepsy (MTLE), more severe impairment in the ipsilateral than
the contralateral hemisphere white matter tracts, including Superior Longitudinal Fasciculus (SLF), are
demonstrated on diffusion tensor imaging (DTI). Many clinicians and researchers conclude tha...
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In patients with Medial Temporal Lobe Epilepsy (MTLE), more severe impairment in the ipsilateral than
the contralateral hemisphere white matter tracts, including Superior Longitudinal Fasciculus (SLF), are
demonstrated on diffusion tensor imaging (DTI). Many clinicians and researchers conclude that drawing
regions of interest (ROI) in the white matter can demonstrate these asymmetries. In this study we
demonstrate that fractional anisotropy (FA) values derived from manually drawing ROI’s on diffusion
tensor imaging (DTI) of SLF differ between the side of seizure onset compared to the contralateral side
in each individual patient with MTLE does not demonstrate these previous conclusions. We therefore
believe that clinicians should recognize that this method of measurement can be inaccurate and should
not be interpreted independently
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2 years ago