Spatio-temporal filtering properties of a dendritic cable with active spines: a modeling study in the spike-diffuse-spike framework

The spike-diffuse-spike (SDS) model describes a passive dendritic tree with active dendritic spines. Spine-head dynamics is modeled with a simple integrate-and-fire process, whilst communication between spines is mediated by the cable equation. In this paper we develop a computational framework that allows the study of multiple spiking events in a network of such spines embedded on a simple one-dimensional cable. In the first instance this system is shown to support saltatory waves with the same qualitative features as those observed in a model with Hodgkin-Huxley kinetics in the spine-head. Moreover, there is excellent agreement with the analytically calculated speed for a solitary saltatory pulse. Upon driving the system with time varying external input we find that the distribution of spines can play a crucial role in determining spatio-temporal filtering properties. In particular, the SDS model in response to periodic pulse train shows a positive correlation between spine density and low-pass temporal filtering that is consistent with the experimental results of Rose and Fortune [1999, Mechanisms for generating temporal filters in the electrosensory system. The Journal of Experimental Biology 202, 1281-1289]. Further, we demonstrate the robustness of observed wave properties to natural sources of noise that arise both in the cable and the spine-head, and highlight the possibility of purely noise induced waves and coherent oscillations.

Future Selves: Career choices of young disabled people

There is growing recognition that gaining the views of young people is crucial for understanding issues that affect their lives. However, to date, very little is known about the way in which disabled children, make sense of their identities, and create a sense of their past and their imagined futures over time. This three year study, funded by the European Social Fund, and conducted by Dr Sonali Shah and colleagues at the University of Nottingham, used various methods to explore how physically disabled students, in full-time special or mainstream education, make choices concerning their occupational futures. It identified the factors that shape their educational and career related choices and chances, and explored how social relations, social processes, and social policies influenced the extent to which their aspirations were achieved. This study presents disabled children and young people as critical social actors who are telling their own stories of how social structures and processes shape their choices and aspirations for their future selves. It illustrates the importance of consulting children and young people about issues concerning their lives, and not rely solely on adults’ conceptions of childhood. The young disabled people’s experiences and views can be used to develop a new flexible system which offers the benefits of mainstream and special education, and facilitates young disabled people’s self-determination to make choices to participate in and contribute to their independent futures.