The multifaceted impact of frontal lobe lesions on behaviour: Lessons from history

The frontal lobe (FL) occupies a third of the human brain with extensive net workconnections and neuronal circuits with other parts of the brain as well as the spinal cord.Lesions varying from head trauma to tumours, neurodegenerative and infectious diseasesin the FL have been associated with post-injury manifestations of behavioural andpersonality changes leading to imbalance in emotion processing and even moraljudgments. Moreover, injury in the FL reportedly leads to speech difficulties, dementiaand physical abnormalities such as loss of motor skills. This chapter explores thecontradicting studies regarding the relationship between injured FL and abnormalbehaviours, which have been thoroughly discussed in the scientific literatures. Thischapter investigates the actual role of the FL in determining human behaviours byanalysing historical data and comparing them with more recent findings fromneuropsychiatric disorders. The wide range of possible outcomes and most likely, theunpredictable prognosis after FL injury limit the success rate of our current therapeuticinterventions, although, approaches using Cognitive Behaviour Therapy, Comprehensive-Holistic Rehabilitation Programs and other psychological treatments have been tried torestore balance in the altered behaviours. Although most of the mechanisms of FL lesionsaltering human behaviours are still unclear, converging lines of evidences suggested thatspecific regions within the FL are responsible for selective behavioural changes. One and half century after the first description of acquired behavioural changesfollowing FL trauma in Phineas Gage, we are still at a starting point for research touncover the exact mechanisms for brain-behaviour interaction and develop effectivetreatments.