A brief and incomplete history of the study of brain and behaviour

Greek mythology The hypothesis that the mind, soul or psyche is responsible for behaviour has roots in Greek mythology Psyche was a human who became immortal after completing a number of almost impossible tasks Her psyche became separate from her body

Greek mythology Aristotle (350 BC) alluded to Greek mythology when he suggested that all human intellectual functions were carried out by the mind (psyche) However, Aristotle thought that the mind was located in the heart - he thought the brain was just there to cool the blood

Other Greek thinkers, such as Hippocrates and Galen, did regard the brain to be the seat of intellect and the organ that controls behaviour: Not only our pleasure, our joy and our laughter but also our sorrow, pain, grief and tears rise from the brain, and the brain alone. With it we think and understand, see and hear, and we discriminate between the ugly and the beautiful, between what is pleasant and what is unpleasant and between good and evil (Hippocrates, 400 BC).

Independent bodies and brains Rene Descartes ( ) wrote an influential book on mind and brain He took a philosophical position that both a nonmaterial mind and the material body contribute to behaviour Cartesian dualism

Accidental neuroscience In 1838 Phineas Gage was the foreman of a railway construction gang in New England, USA He was responsible for laying new tracks which involves blasting hard rocks to provide a more level path Gage was considered ‘an efficient and capable man’ by his employers and was well liked by his colleagues One day a rock charge blows up in his face An iron rod entered Gage’s cheek and penetrated the base of his skull, leaving through the top of his head.

Gage survives, is able to walk without assistance, could touch, hear, see (through his right eye) and speak However, some aspects of his personality were changed He became ‘fitful, irreverent, and indulged in the grossest profanity’ This resulted in him losing his job and his friends Gage was no longer Gage

Localisation of function The concept of functional localization began with Franz Gall and the phrenologists in the early 19th century Phrenology (reading personality from bumps on the head) is a discredited science but...

Localisation of function Phrenology did suggest that the brain could be divided up into many separate organs that were responsible for different behavioural faculties Support for the concept of localization came from neurologists who demonstrated that brain lesions had specific effects on behaviour

Localisation of function John Hughlings Jackson, an English neurologist, was one of the first to recognise the localizational view He noted that lesions to the right side of the brain affected visual-spatial processes more than lesions to the left side of the brain

Localisation of function Pierre Paul Broca and Carl Wernike showed how lesions to other parts of the brain (left hemisphere) affected language capability

Parts of the brain

Protection The brain is well protected Bony skull 3 protective sheets of tissue Space in the brain is filled with fluid: –Cerebrospinal fluid (CSF) –Acts as a shock absorber –Blood-brain barrier protects the brain from blood-borne pathogens.

A brain of two halves Left hemisphere and right hemisphere They are joined by the corpus callosum Made up of axons of neurons that communicate information between hemispheres

Wrinkles Cerebral cortex forms the outer layer of the forebrain Made up of grey matter (lots of cell bodies for integration) It appears wrinkled as it is folded Folding allows more outer cortex to be fitted into a smaller space A groove is called a sulcus (pl sulci) Between grooves is a gyrus (pl gyri)

Major parts

Brain stem Mid brain: Nerve pathway of cerebral hemispheres/Auditory and Visual reflex centers Pons: Respiratory Center, swallowing and equilibrium Medulla Oblongata: Crossing of motor tracts/Cardiac Center/Respiratory Center

Cerebellum – Plays a role in commands for motor action Organization of action including language production Integrates information from external and internal sources Lesions cause difficulty in voluntary muscle movement and balance. Toates p119 Major parts

Occipital lobe: visual perception system E.g., visuospatial processing, discrimination of movement and colour discrimination Some forms of epilepsy originate here. Lesions can also cause visual hallucinations

Major parts Parietal lobe – Several portions are important in language processing Also, somatosensation: touch, pain, temperature sense, and limb proprioception (limb position) Damage to the right hemisphere of this lobe results in the loss of imagery, visualization of spacial relationships and neglect of left side space and left side of the body. Damage to the left hemisphere of this lobe will result in problems in mathematics, long reading, writing and understanding symbols.

Major parts Temporal lobe – Contains sensory areas associated with hearing Also, memory and interpretation of what your senses are telling you Wernicke’s aphasia: language comprehension issue

Major parts Frontal lobe – emotional control centre and home to our personality Motor function, problem solving, spontaneity, memory, language, initiation, judgement, impulse control, and social and sexual behaviour Effects of frontal damage can be a dramatic change in social behaviour (i.e Phineas Gage)

Memory Hippocampus Involved in the formation of memory, both long and short term. Alzheimer's Disease is associated with deterioration of this area of the brain.