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William W Lytton

Publications and source records attributed to William W Lytton.

5 recordsLinked to original sources
PubMed2006

Neural Query System: Data-mining from within the NEURON simulator.

We have developed a simulation tool within the NEURON simulator to assist in organization, verification, and analysis of simulations. This tool, denominated Neural Query System (NQS), provides a relational database system, a query function based on the SELECT function of Structured Query Language, and data-mining tools. We show how NQS can be used to organize, manage, verify, and visualize parameters for both single cell and network simulations. We demonstrate an additional use of NQS to organize simulation output and relate outputs to parameters in a network model. The NQS software package is available at http://senselab. med.yale.edu/senselab/SimToolDB.

Animals↗
PubMed2005

Computer simulation of epilepsy: implications for seizure spread and behavioral dysfunction.

Hippocampal area CA3 has been one of the most intensively studied brain regions for computer models of epileptiform activity. As physiological studies begin to extend outward to other hippocampal and parahippocampal areas, we must extend these models to understand more complex circuitry containing diverse elements. Study of subiculum is of particular interest in this context, as it is a structure of intermediate complexity, with an inchoate columnar and laminar organization. In addition to helping us understand seizures, modeling of these structures will also help us understand the genesis of physiological activity patterns that are below threshold for seizure generation. Such modeling can also serve as a basis for speculation regarding the nonictal behavioral consequences of epilepsy.

Behavior↗
PubMed2005

Independent variable time-step integration of individual neurons for network simulations.

Realistic neural networks involve the coexistence of stiff, coupled, continuous differential equations arising from the integrations of individual neurons, with the discrete events with delays used for modeling synaptic connections. We present here an integration method, the local variable time-step method (lvardt), that uses separate variable-step integrators for individual neurons in the network. Cells that are undergoing excitation tend to have small time steps, and cells that are at rest with little synaptic input tend to have large time steps. A synaptic input to a cell causes reinitialization of only that cell's integrator without affecting the integration of other cells. We illustrated the use of lvardt on three models: a worst-case synchronizing mutual-inhibition model, a best-case synfire chain model, and a more realistic thalamocortical network model.

Action Potentials↗
PubMed2003

Computer model of passive signal integration based on whole-cell in vitro studies of rat lateral geniculate nucleus.

Computer models were used to investigate passive properties of lateral geniculate nucleus thalamocortical cells and thalamic interneurons based on in vitro whole-cell study. Two neurons of each type were characterized physiologically and morphologically. Thalamocortical cells transmitted 37% of steady-state signal orthodromically (distal dendrite to soma) and 93% antidromically (soma to distal dendrite); interneurons transmitted 18% orthodromically and 53% antidromically. Lowering membrane resistance caused a dramatic drop in steady-state signal transmission. Simulation of brief signals such as orthodromically transmitted postsynaptic potentials and antidromically transmitted action potentials showed relatively poor transmission due to the low-pass filtering property of dendrites. This attenuation was particularly pronounced in interneurons. By contrast, bursts of postsynaptic potentials or action potentials were relatively well transmitted as the temporal summation of these recurring signals gave prolonged depolarizations comparable to prolonged current injection. While synaptic clustering, active channels and reduction of membrane resistance by ongoing synaptic activity will have additional profound effects in vivo, the present in vitro modelling suggests that passive signal transmission in neurons will depend on type of signal conveyed, on directionality and on membrane state. This will be particularly important for thalamic interneurons, whose presynaptic dendrites may either work independently or function in concert with each other and with the soma. Our findings suggest that bursts may be particularly well transmitted along dendrites, allowing firing format to alter the functional anatomy of the cell.

Action Potentials↗