the brain

The Cerebral Cortex - Functional zones

The cortex is divided into two zones based on their function:

• I - Projection areas – serve as receiving areas for sensory information and as dispatching centers for motor commands

• II - Association areas – the remaining 2/3rds of the cortex is devoted to higher mental functions like planning, perceiving, remembering, thinking, and speech

I - projection areas

Motor projection areas of the cortex are linked with control parts of the body

• These can be mapped with a high degree of accuracy to create a motor homonculus, or a schema of the body as it is represented on the cortex

sensory areas

Each part of our body also has a designated area of the cortex devoted to sensation – called the somatosensory area

• This map can be used to create a sensory homunculus of the region of the brain devoted to sensation

• Other parts of the cortex are devoted to the different senses

• These are the visual cortex, and the auditory cortex

II - association areas

Association areas are related to complex mental functions like speech, thinking, and remembering

• The precise locations of these activities can be discovered through lesions (damaged tissue) in the brain

localization

Prior to the 20th century – main source of research into brain function – case studies

• Lacked cause effect analysis

• Eg. Phineas Gage, Broca’s Area, Wernicke’s aphasia

broca’s aphasia

a form of expressive aphasia generally caused by lesions in a region of the left frontal lobe

• An association area that borders on the part of the motor projection zone that controls speech muscles

wernicke’s aphasia

• A form of receptive aphasia caused by lesions near the auditory projection zones of the parietal and temporal lobes impairing comprehension and production of language

• Patients can make out words and sound patterns but cannot fully grasp their meaning

reorganization & neurogenesis

While much of the nervous system does not regenerate itself after damage and some areas seem preassigned to specific functions, the brain can exhibit changes in structure in response to new patterns of use resulting from the loss of these areas and functions

plasticity

the brain's ability to modify itself after damage

barrinaga & sadato

Blind people who read Braille grow the area of their cortex devoted to that finger

neurogenesis

production of new pyrimidal cells in the brain in response to damage

sperry & gazzaniga - lateralization

Severing the corpus callosum – the wide band of axon fibers connecting the two hemispheres of the brain and transmitting information between them – is a treatment for drug resistant seizure disorders

• Results in unique neurological behaviours that hint at clues to the functioning of the brain

Define lateralization and give two examples

Specific behaviours or cognitive functions are localized to one half of the cerebral cortex.

Left – reading, writing, speaking, arithmetic, and understanding