13,934 research outputs found
Theoretical and computational tools to model multistable gene regulatory networks
The last decade has witnessed a surge of theoretical and computational models
to describe the dynamics of complex gene regulatory networks, and how these
interactions can give rise to multistable and heterogeneous cell populations.
As the use of theoretical modeling to describe genetic and biochemical circuits
becomes more widespread, theoreticians with mathematics and physics backgrounds
routinely apply concepts from statistical physics, non-linear dynamics, and
network theory to biological systems. This review aims at providing a clear
overview of the most important methodologies applied in the field while
highlighting current and future challenges, and includes hands-on tutorials to
solve and simulate some of the archetypical biological system models used in
the field. Furthermore, we provide concrete examples from the existing
literature for theoreticians that wish to explore this fast-developing field.
Whenever possible, we highlight the similarities and differences between
biochemical and regulatory networks and classical systems typically studied in
non-equilibrium statistical and quantum mechanics.Comment: 73 pages, 12 figure
Eligibility Traces and Plasticity on Behavioral Time Scales: Experimental Support of neoHebbian Three-Factor Learning Rules
Most elementary behaviors such as moving the arm to grasp an object or
walking into the next room to explore a museum evolve on the time scale of
seconds; in contrast, neuronal action potentials occur on the time scale of a
few milliseconds. Learning rules of the brain must therefore bridge the gap
between these two different time scales.
Modern theories of synaptic plasticity have postulated that the co-activation
of pre- and postsynaptic neurons sets a flag at the synapse, called an
eligibility trace, that leads to a weight change only if an additional factor
is present while the flag is set. This third factor, signaling reward,
punishment, surprise, or novelty, could be implemented by the phasic activity
of neuromodulators or specific neuronal inputs signaling special events. While
the theoretical framework has been developed over the last decades,
experimental evidence in support of eligibility traces on the time scale of
seconds has been collected only during the last few years.
Here we review, in the context of three-factor rules of synaptic plasticity,
four key experiments that support the role of synaptic eligibility traces in
combination with a third factor as a biological implementation of neoHebbian
three-factor learning rules
Essay: Developing Appropriate Standards for Achieving Diversity in Faculty Appointments
I am writing today to talk about diversity within law school faculties. And when I say “diversity,” I mean all sorts of diversities, not just the ones that most of those who address the issue tend to focus on. I have, for many years, been thinking about the different types of diversities that seem crucial to a law school, and the appropriate ways of achieving them. Part I lists the categories of diversity that I think are important to considering diversity within law school faculties. It then indicates a problem that inheres with this list. Part II suggests how different schools may view the appropriateness of achieving some of these diversities. And finally, in Part III, I will come to the main thesis of this piece and propose how schools can achieve the diversities they deem desirable
- …