Dorsolateral prefrontal cortex

The dorsolateral prefrontal cortex (DLPFC or DL-PFC) is an area in the prefrontal cortex of the brain of humans and non-human primates. It is one of the most recently derived parts of the human brain. It undergoes a prolonged period of maturation which lasts until adulthood. The DLPFC is not an anatomical structure, but rather a functional one. It lies in the middle frontal gyrus of humans (i.e., lateral part of Brodmann's area (BA) 9 and 46). In macaque monkeys, it is around the principal sulcus (i.e., in Brodmann's area 46). Other sources consider that DLPFC is attributed anatomically to BA 9 and 46 and BA 8, 9 and 10. The dorsolateral prefrontal cortex (DLPFC or DL-PFC) is an area in the prefrontal cortex of the brain of humans and non-human primates. It is one of the most recently derived parts of the human brain. It undergoes a prolonged period of maturation which lasts until adulthood. The DLPFC is not an anatomical structure, but rather a functional one. It lies in the middle frontal gyrus of humans (i.e., lateral part of Brodmann's area (BA) 9 and 46). In macaque monkeys, it is around the principal sulcus (i.e., in Brodmann's area 46). Other sources consider that DLPFC is attributed anatomically to BA 9 and 46 and BA 8, 9 and 10. The DLPFC has connections with the orbitofrontal cortex, as well as the thalamus, parts of the basal ganglia (specifically, the dorsal caudate nucleus), the hippocampus, and primary and secondary association areas of neocortex (including posterior temporal, parietal, and occipital areas). The DLPFC is also the end point for the dorsal pathway (stream), which is concerned with how to interact with stimuli. An important function of the DLPFC is the executive functions, such as working memory, cognitive flexibility, planning, inhibition, and abstract reasoning. However, the DLPFC is not exclusively responsible for the executive functions. All complex mental activity requires the additional cortical and subcortical circuits with which the DLPFC is connected. The DLPFC is also the highest cortical area that is involved in motor planning, organization and regulation. As the DLPFC is composed of spatial selective neurons, it has a neural circuitry that encompasses the entire range of sub-functions necessary to carry out an integrated response, such as: sensory input, retention in short-term memory, and motor signaling. Historically, the DLPFC was defined by its connection to: the superior temporal cortex, the posterior parietal cortex, the anterior and posterior cingulate, the premotor cortex, the retrosplenial cortex, and the neocerebellum. These connections allow the DLPFC to regulate the activity of those regions, as well as to receive information from and be regulated by those regions. The DLPFC is known for its involvement in the executive functions, which is an umbrella term for the management of cognitive processes, including working memory, cognitive flexibility, and planning. A couple of tasks have been very prominent in the research on the DLPFC, such as the A-not-B task, the delayed response task and object retrieval tasks. The behavioral task that is most strongly linked to DLPFC is the combined A-not-B/delayed response task, in which the subject has to find a hidden object after a certain delay. This task requires holding information in mind (working memory), which is believed to be one of the functions of DLPFC. The importance of DLPFC for working memory was strengthened by studies with adult macaques. Lesions that destroyed DLPFC disrupted the macaques’ performance of the A-not-B/delayed response task, whereas lesions to other brain parts did not impair their performance on this task. DLPFC is not required for the memory of a single item. Thus, damage to the dorsolateral prefrontal cortex does not impair recognition memory. Nevertheless, if two items must be compared from memory, the involvement of DLPFC is required. People with damaged DLPFC are not able to identify a picture they had seen, after some time, when given the opportunity to choose from two pictures. Moreover, these subjects also failed in Wisconsin Card-Sorting Test as they lose track of the currently correct rule and persistently organize their cards in the previously correct rule. In addition, as DLPFC deals with waking thought and reality testing, it is not active when one is asleep. Likewise, DLPFC is most frequently related to the dysfunction of drive, attention and motivation. Patients with minor DLPFC damage display disinterest in their surroundings and are deprived of spontaneity in language as well as behavior. Patients may also be less alert than normal to people and events they know. Damage to this region in a person also leads to the lack of motivation to do things for themselves and/or for others. The DLPFC is involved in both risky and moral decision making; when individuals have to make moral decisions like how to distribute limited resources, the DLPFC is activated. This region is also active when costs and benefits of alternative choices are of interest. Similarly, when options for choosing alternatives are present, the DLPFC evokes a preference towards the most equitable option and suppresses the temptation to maximize personal gain. Working memory is the system that actively holds multiple pieces of transitory information in the mind, where they can be manipulated. The DLPFC is important for working memory; reduced activity in this area correlates to poor performance on working memory tasks. However, other areas of the brain are involved in working memory as well. There is an ongoing discussion if the DLPFC is specialized in a certain type of working memory, namely computational mechanisms for monitoring and manipulating items, or if it has a certain content, namely visuospatial information, which makes it possible to mentally represent coordinates within the spatial domain.