Jette Hannibal - Inthinking The nervous system NS: gathers and processes information, produces responses to stimuli, coordinates the workings of different cells CNS (brain + spinal cord): receives, processes, interprets, and stores incoming sensory information (e.g. Taste, state of internal organs) PNS: deals with input and output of CNS through sensory and motor neurons.

Jette Hannibal - Inthinking The nervous system Millions of neurons in different sizes and shapes organized in a network for transmission of information. Communication between neurons: electric conduction and chemical transmission A large concentration of neurons in the brain and the spinal cord. 80% are found in the brain’s Cerebral cortex Neurons: basic structural unit of NS

Jette Hannibal - Inthinking Structure of neurons Cell body or nucleus (contains DNA) Dendrites: information transmission Axons: the cell body. Terminal buttons: storage of neurotransmitters. Synaptic gap: between dendrites and terminal buttons. Where neurotransmitters “pass” information from neuron to neuron.

Jette Hannibal - Inthinking Neuron

Jette Hannibal - Inthinking Neuronal communication Within neurons: Action potential Between neurons: Synaptic transmission of neurotransmitters

Jette Hannibal - Inthinking Action potential Electro-chemical messages AP occurs when a neuron sends information down an axon AP caused by an exchange of Sodium and Potassium ions across the neural membrane

Jette Hannibal - Inthinking Neurotransmitters Chemical messengers from neuron to neuron. Messages may also travel from neurons to to muscles and organs in the body, such as lungs or the intestines.

Jette Hannibal - Inthinking Synaptic gap Synaptic vesicles with neurotransmitters at one side of the gap (terminal buttons): pre- synaptic gap. Like “keys” Receptor sites for neurotransmitters (like locks) at the other side of the gap: post- synaptic gap 1/10000 of a second to travel across the synaptic gap

Jette Hannibal - Inthinking Brain, neurons, neurotransmitters – how it works bSyc

Jette Hannibal - Inthinking Neurotransmitters Produced in the terminal buttons and diffused across the synaptic gap to bind to receptor sites. The neuron on the postsynaptic side of the gap more or less likely to fire as a result of synaptic transmission. Psychoactive drugs can change properties of neurotransmitter release, neurotransmitter reuptake and the availability of receptor binding sites.

Jette Hannibal - Inthinking Neurotransmitter processes Excitatory: increases the frequency of action potential Inhibitory: decreases the frequency of action potential De-activation: effect of neurotransmitter stopped (destroyed by special enzyme) Re-uptake: reabsorbed by the terminal buttons. Drugs can inhibit re-uptake so that the neurotransmitter remains longer in the synaptic gap

Jette Hannibal - Inthinking Brief intro to principles of neurotransmission Click here to see how neurotransmission works. Click here to see how neurotransmission works.

Jette Hannibal - Inthinking Examples of neurotransmitters Dopamine: (inhibitory) Controls arousal levels in the brain; vital for physical motivation (e.g. associated with craving in addiction) Dopamine Serotonin: (inhibitory) Controls mood and anxiety levels High levels of serotonin are associated with optimism. Acetylcholine (ACh): (excitatory) Controls activity in the brain connected with attention, learning and memory Noradrenaline: (excitatory) involved in mental arousal and elevated mood

Jette Hannibal - Inthinking Dopamine and serotonin

Jette Hannibal - Inthinking The reward pathway - dopamine Stimulation of the reward center is linked to release of dopamine Rats will continuously press a lever that gives a small electrical stimulation to the pleasure center