Biological Rhythms; Circadian, Infradian and Ultradian.

The role of endogenous pacemakers is to set the free-running internal rhythm. It is an internal biological ‘clock’ that allows organisms to control their internal rhythms and helps animals to anticipate cyclical events (e.g., the coming of night). These are innate. The SCN is the endogenous pacemaker that controls the circadian sleep/wake cycle. The SCN sends signals to the pineal gland, directing it to increase melatonin production at night. Melatonin induces sleep by inhibiting brain mechanisms that keep us awake. The SCN therefore maintains the link between light and melatonin production.

Ways of Studying the Brain: Scanning Techniques, including Functional Magnetic Resonance Imaging (fMRI); Electroencephalogram (EEGs) and Event-Related Potentials (ERPs); Post-Mortem Examinations.

The brain is the main focus of neuroscience. Studying the brain gives us important insights into the underlying foundations of our behaviour and mental processes. A variety of methods are used by scientists in order to study the different areas and functions of the brain. Some involve scanning the living brain, looking for patterns of electrical activity associated with performance of particular tasks. Other methods involve studying sections of a deceased brain to investigate anatomical reasons for behaviour observed when the patient was alive.

The Process of Synaptic Transmission

• Initially, the electrical nerve impulse travels down the neuron and prompts the release of neurotransmitters (chemicals in the brain) at the presynaptic terminal.
• These chemicals are then released into the synaptic fluid of the synapse.
• The adjacent neuron must then quickly take up the neurotransmitter from the fluid and convert this into an electrical impulse to travel down the terminal to the next pre-synaptic terminal (allowing the impulse to be transmitted on).
• This process occurs at high speed.

The structure and function of sensory, relay and motor neurons.

The nervous system is composed of specialised cells called neurons. The neurons form pathways in the brain and throughout the body by being connected to one another by synapses.

There are about 100 billion neurons or nerve cells in the average nervous system. Neurons vary in size and shape. The neurons are specialised for communication whether this is between other neurons or with other organs in the body such as the heart or stomach.

There are three main neurons, all of which have different roles to play – Sensory, Relay and Motor Neuron.