Disorders of Reasoning

Reasoning depends upon intact brain systems across the lifespan. There are a variety of levels of impairment that people experience based on what region of the brain is damaged. Reasoning can involve the intake of new information, identifying and representing the context of the situation, manipulating information, recalling previous solutions, and projecting into the future to imagine the effectiveness of a solution. Attention and memory are important for the representation of the current premises and context in a reasoning task. Once information is attended to, it must be maintained in working memory and possibly transformed depending upon the nature of the task. The ability to recall relevant information from long-term memory at the appropriate time can also determine how we reason. Intact prefrontal cortex (PFC) and parietal cortex are essential for effective attention and working memory performance. Strokes and traumatic brain injuries can impair these areas. Dementias can lead to decline in attention, working memory, inhibitory control, and retrieval of long-term memories. Social and emotional processing are important for reasoning about other people's behavior, making appropriate decisions based on risk, and moral reasoning. Frontal lobe impairments in the medial and orbitofrontal regions can lead to impaired decision making and excessive risk taking. Intact frontal regions are also important for advancing our moral development in addition to carrying out appropriate social behavior.