As mentioned by others thats the default setup in MATLAB.
Coming to comparision between different activation functions.
It is generally recommended to use ReLU as the activation function. If your model suffers form dead neurons during training we should use leaky ReLu or Maxout function.
The Sigmoid and Tanh are generally not preferred as they suffer with vanishing Gradient Problem which causes a lots of problems to train,degrades the accuracy and performance of a deep Neural Network Model.