LOCALIZATION & LATERALIZATION OF BRAIN FUNCTION

INTRODUCTION:  The Brain is the only body organ to exhibit both localisation and lateralisation of function.  Localization = Different areas of the brain do different things.  Lateralization = Each brain hemisphere is adapted to certain functions better than the other.

Structure of the Cortex Why do our brains have so many folds in them?

Four lobes of the cerebral cortex Frontal Motor activity Higher level intelligence Planning Problem solving Emotions Self-awareness Parietal Bodily sensations, e.g., pain, heat Body movement Temporal Hearing Vision Smell Memory Occipital Primary visual area of the brain

Four lobes of the cerebral cortex Frontal Parietal Temporal Occipital

AN EXAMPLE OF BRAIN LOCALIZATION:  Different areas of brain associated with same functions.  Broca's area: Articulation of speech. Patients with Broca's aphasia can understand speech but cannot articulate it themselves.  Wernicke's area: Understanding language. Patients with Wernicke's aphasia can understand language and reply in fluent, yet garbled or meaningless sentences.

Functions of the Cortex The motor cortex – controls movement of the Body. The motor cortex sends messages from The brain to the body. Right side of the brain controls the left side of the body, and vice versa. Sensory Functions - Receive information from from different senses and in different areas of the brain the information is processed.

THE CORTEX > Emotion and experience, association areas, frontal motor area. > Sense of touch in different parts of the body. > Hearing, language and memory for objects. > Vision. The cortex is the part of the brain which is most strongly associated with the mind and general consciousness.

BRAIN LATERALIZATION & THE CEREBRAL HEMISPHERES  Each hemisphere responsible for the opposite side of the body.  Left hemisphere receives information from right field of view and vice versa  Work with split brain patients helped to identify differences in function of the two hemispheres of the brain.  Hemispheric specialization also linked with handedness, in that right handed people have a dominant left hemisphere and so on.

STUDYING THE BRAIN  EEG (electroencephalogram)  Brain Scans (MRI, PET, CAT)  Electrical Stimulation

3 EARLY INVESTIGATORS OF BRAIN FUNCTION 1) Franz Josef Gall ( )  Cranioscopy, or phrenology Size + shape cranium = Size + shape brain Mental abilities innate and fixed Level of development of ability reflection of size of cerebral organ

2) Jean-Pierre Flourens ( )  First experimental lesions in brain.  Not precise; severe brain damage occurred in some cases.  No specific areas found, but different lesions caused different problems.

3) Paul Broca ( )  First put forward for specific language centre In the brain.  Patient with brain damage understood everything said to him, but could only say 'tan' in reply (Broca's aphasia).  Patient with similar symptoms found to have brain damage in same area in post mortem examination.