Central nervous system Psychology Additional information

Frontal lobe Responsible for our most complex mental behaviours, such as planning, problem-solving, thinking, memory, learning and analysing. Responsible for the control of voluntary movement. Contains the primary motor cortex, which directs the body’s skeletal muscles.

Frontal lobe: Broca’s Area Named after Paul Broca who identified it Found in the left frontal lobe and is an important language centre. Broca’s area directs the part of the primary motor cortex that controls muscles of the throat, mouth, jaw, tongue and face. By controlling the movement of these muscles, Broca’s area is primarily responsible for the production of articulate (clear and fluent) speech. It is also involved in the structuring sentences and analysing grammar. If Broca’s area is damaged, a person may be unable to produce clear and articulate speech.

Frontal lobe – motor cortex

Parietal lobe Responsible for processing bodily (somatic) sensations. Touch, temperature, pressure and other somatic sensations are registered in the parietal lobe’s primary somatosensory cortex.

Temporal lobe – somatosensory cortex

Occipital lobe Registering and processing visual information transmitted from the retinas of both eyes through the optic nerve The primary visual cortex contains a variety of neurons specialised to respond to specific features of visual information – colour, shape, motion Damage to the occipital lobe may result in visual impairment even if the eyes and the optic nerve are uninjured. Example: individuals who experience a tumour in one of their occipital lobes may experience blind spots in their vision.

Temporal lobe Responsible for processing auditory (sound) information received by both ears Right temporal lobe is specialised to process non-verbal sounds (for example, the sound of a siren or a door slamming). Left temporal lobe processes verbal sounds that are associated with language.

Temporal lobe - Wernicke’s Area Identified by Carl Wernicke Generally found in the left temporal lobe It is connected to Broca’s area by nerve fibres (arcuate fasciculus). Responsible for accessing words stored in memory and the comprehension of speech and formulation of meaningful sentences. People with damage to Wernicke’s area can hear words or see them when written, but they do not understand their meaning. They can pronounce strings of words but their grammatical errors make their speech meaningless

Association areas Association areas integrate information. They combine and process sensory information and link it with pre-existing ideas, concepts and memories. This role is crucial to our ability to recognise familiar objects, people and experiences. Example if you see a rose, the primary visual cortex would register the shape, colour, size and texture of the rose; and the association cortex near the visual cortex would link that information with past knowledge of a rose (its name, the fact it has thorns, a mental comparison with other flowers)

Corpus callosum A thick band of nerve fibres in the middle of the brain that connects the left and right hemispheres and transfers information registered in one hemisphere to the other. Although each hemisphere can perform specialised functions, most of our thoughts, feelings and behaviours involve both hemispheres working together.

Roger Sperry & split brain studies Sperry received the Nobel prize in physiology of medicine for his discoveries concerning the functional specialization of the cerebral hemispheres. With the help of so called "split brain" patients, he carried out experiments, increasing our knowledge about the left and right hemispheres was revealed. The studies demonstrated that the left and right hemispheres are specialized in different tasks.

Left and right hemispheres Left side Responsible for analytical and verbal tasks. The left side speaks much better than the right side Right side Responsible for space perception tasks and music, the creative part. Example: making a map or giving directions on how to get to your home from the bus station. It can only produce rudimentary words and phrases, but contributes emotional context to language. Without the help from the right hemisphere, you would be able to read the word "pig" for instance, but you wouldn't be able to imagine what it is.

Psychology Additional information Action potentials Psychology Additional information

Steps in an action potential When a neuron is at ‘rest’, the inside is negatively charged in relation to the outside. This is called the resting potential The resting potential of a neuron is -70mV Steps in an action potential A stimulus occurs The dendrites receive the signal and this results in depolarisation of the neuron. Depolarisation means that the resting potential moves toward 0mV.

Steps in an action potential When depolarisation reaches -55 mV, the neuron will ‘fire’ an action potential. This occurs through the movement of ions across the cell membrane. This is called the threshold. If the neuron does not reach the critical threshold level, then no action potential will fire. The neuron will depolarise from -70mV to 30mV Once the action potential has been conducted and transmitted, the neuron will repolarise to -70mv

All or none principle ‘All or none’ principle When the threshold potential of -55mV is reached, an action potential of a fixed size will always fire. The size of the action potential is always the same. There are no big or small action potentials in one nerve cell - all action potentials are the same size. Therefore, the neuron either does not reach the threshold or a full action potential is fired