1. An integrated self-contained recorder of biological data for a small animal comprising: a recorder, comprising: a converter for conversion of at least one biological signal to digital data, a data storage unit for storing the digital data, a data output for transporting the stored digital data from the recorder after a recording session, a power source, and, an electrical connector; and a head connector adapted to attach to a head of a small animal, the head connector containing at least one sensor of a biological signal from the small animal, wherein the biological signal comprises electrical brain activity, the electrical connector has a complementary structure to receive and connect to the head connector, and the recorder removably connects to the head connector at the complementary structure of the electrical connector; wherein the recorder is mechanically affixed to the head connector via the electrical connector to fixate the recorder over the animal's head, wherein the recorder is adapted to be carried over the animal's head, wherein the recorder is adapted to disconnect from the head connector by disconnecting the electrical connector; wherein the recorder or another recorder is adapted to reconnect to the head connector, and the head connector transfers electronic signals from the sensor to the recorder by the electrical connector.