LOCALIZATION LATERALIZATION OF BRAIN FUNCTION INTRODUCTION The Brain

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.

3 EARLY INVESTIGATORS OF BRAIN FUNCTION 1) Franz Josef Gall (1758 -1828) 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 (1794 -1867) 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 (1824 -1880) 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.

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 articulate speech but are unable to understand it. Other brain areas concerned with speech double up with other functions; e. g. memory, emotions, concentration

THE CORTEX Emotion, experience, planning, initiative, language production , frontal motor area. > Senses, touch , monitoring of body parts > Vision. Hearing, language comprehension and memory The cortex is the part of the brain which is most strongly associated with the mind and general consciousness.

THE LIMBIC SYSTEM Hypothalamus - basic drives; temperature control, hunger, thirst & sex Hippocampus - memory function and learning Amygdala - basic emotions (fear & rage), forming emotional memories.

THE CEREBELLUM & THE BRAIN STEM Cerebellum- movement and balance. Medulla - regulation of vital function (breathing, circulation). Pons – plays role in sleep and arousal Reticular formation - relay network controlling sensory input and regulating arousal, alertness and sleep.

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, CA Electrical Stimulation