Every so often a new neural network makes headlines for solving a computation problem. It is sometimes hard for me to judge how impressive these achievements are without diving into the details of the models. But my criteria are always the same and it should be easy for those who are familiar with their models to evaluate based on these criteria. For this purpose I have made a flowchart for how impressed I would be at a neural network. If you know of a new neural net that reaches “wow” please let me know about it, and if it reaches “mind-blown” you have permission to wake me up in the middle of the night – since I know no examples.Continue reading “The Researcher’s Guide for Being Mind Blown by a Neural Network”
How does the brain keep track of time? This question has been intriguing neuroscientists for decades. Circadian clocks, which oscillate every 24 hours, are known to be implemented at the level of molecules and genes. But it is widely believed that keeping track of time for shorter durations (e.g. seconds and minutes) arise from electrical/synaptic activity patterns, not from molecular activity. The idea is that cells can be connected in ways that result in oscillations or sequential activity (e.g. one neuron fires at the 1s mark, the next fires at the 2s mark, etc.). As with most of our theories of short-term memory, if all the cells in a network go silent for a moment the timer falls apart. The spiking activity is what keeps the clock going. This theory has had its opponents, but I think it is fair to say that it has been a commonly held view in neuroscience.
A recent study, however, has made a serious crack in this paradigm. In a series of two papers from the Crickmore lab at Harvard University (one published last year and another last month), Thornquist and colleagues show that a single neuron can keep track of time in a completely silent manner. The time interval they studied was a 7 minute period in mating fruit flies. I believe this is a landmark study that every neuroscientist should know about. So here is my attempt at explaining it in simple terms.Continue reading “A 7 Minute Timer Has Been Discovered in Neurons”