prefrontal cortex prefrontal cortex in mammalian brain anatomy, the prefrontal cortex (pfc) covers the front part of the frontal lobe of the cerebral cortex. the pfc contains the brodmann areas ba8, ba9, ba10, ba11, ba12, ba13, ba14, ba24, ba25, ba32, ba44, ba45, ba46, and ba47. prefrontal cortexbrodmann areas, 8, 9, 10, 11, 12, 13, 14, 24, 25, 32, 44, 45, 46, and 47 are all in the prefrontal cortexdetailspart offrontal lobepartssuperior frontal gyrus middle frontal gyrus inferior frontal gyrusarteryanterior cerebral middle cerebralveinsuperior sagittal sinusidentifierslatincortex praefrontalismeshd017397neuronames2429neurolex idnlx_anat_090801fma224850anatomical terms of neuroanatomy the basic activity of this brain region is considered to be orchestration of thoughts and actions in accordance with internal goals. many authors have indicated an integral link between a person's will to live, personality, and the functions of the prefrontal cortex. this brain region has been implicated in executive functions, such as planning, decision making, working memory, personality expression, moderating social behavior and controlling certain aspects of speech and language. executive function relates to abilities to differentiate among conflicting thoughts, determine good and bad, better and best, same and different, future consequences of current activities, working toward a defined goal, prediction of outcomes, expectation based on actions, and social "control" (the ability to suppress urges that, if not suppressed, could lead to socially unacceptable outcomes). the frontal cortex supports concrete rule learning. more anterior regions along the rostro-caudal axis of frontal cortex support rule learning at higher levels of abstraction. structure definition there are three possible ways to define the prefrontal cortex: as the granular frontal cortex as the projection zone of the medial dorsal nucleus of the thalamus as that part of the frontal cortex whose electrical stimulation does not evoke movements granular frontal cortex the prefrontal cortex has been defined based on cytoarchitectonics by the presence of a cortical granular layer iv. it is not entirely clear who first used this criterion. many of the early cytoarchitectonic researchers restricted the use of the term prefrontal to a much smaller region of cortex including the gyrus rectus and the gyrus rostralis (campbell, 1905; g. e. smith, 1907; brodmann, 1909; von economo and koskinas, 1925). in 1935, however, jacobsen used the term prefrontal to distinguish granular prefrontal areas from agranular motor and premotor areas. in terms of brodmann areas, the prefrontal cortex traditionally includes areas 8, 9, 10, 11, 12, 13, 14, 24, 25, 32, 44, 45, 46, and 47, however, not all of these areas are strictly granular – 44 is dysgranular, caudal 11 and orbital 47 are agranular. the main problem with this definition is that it works well only in primates but not in nonprimates, as the latter lack a granular layer iv. projection zone to define the prefrontal cortex as the projection zone of the mediodorsal nucleus of the thalamus builds on the work of rose and woolsey, who showed that this nucleus projects to anterior and ventral parts of the brain in nonprimates, however, rose and woolsey termed this projection zone "orbitofrontal." it seems to have been akert, who, for the first time in 1964, explicitly suggested that this criterion could be used to define homologues of the prefrontal cortex in primates and nonprimates. this allowed the establishment of homologies despite the lack of a granular frontal cortex in nonprimates. the projection zone definition is still widely accepted today (e.g. fuster), although its usefulness has been questioned. modern tract tracing studies have shown that projections of the mediodorsal nucleus of the thalamus are not restricted to the granular frontal cortex in primates. as a result, it was suggested to define the prefrontal cortex as the region of cortex that has stronger reciprocal connections with the mediodorsal nucleus than with any other thalamic nucleus. uylings et al. acknowledge, however, that even with the application of this criterion, it might be rather difficult to define the prefrontal cortex unequivocally. electrically silent area of frontal cortex a third definition of the prefrontal cortex is the area of frontal cortex whose electrical stimulation does not lead to observable movements. for example, in 1890 david ferrier used the term in this sense. one complication with this definition is that the electrically "silent" frontal cortex includes both granular and non-granular areas. subdivisions according to striedter the pfc of humans can be delineated into two functionally, morphologically, and evolutionarily different regions: the ventromedial pfc (vmpfc) consisting of: the ventral prefrontal cortex (vpfc) the medial prefrontal cortex present in all mammals (mpfc) the lateral prefrontal cortex (lpfc), consisting of: the dorsolateral prefrontal cortex (dlpfc) the ventrolateral prefrontal cortex (vlpfc) present only in primates. the lpfc contains the brodmann areas ba8, ba9, ba10, ba45, ba46, and ba47. some researchers also include ba44. the vmpfc contains the brodmann areas ba12, ba25, ba32, ba33, ba24, ba11, ba13, and ba14. the table below shows different ways to subdivide parts of the human prefrontal cortex based upon brodmann areas. 8 9 10 46 45 47 44 12 25 32 33 24 11 13 14 lateral ventromedial dorsolateral ventrolateral medial ventral the dorsolateral prefrontal cortex is composed of the ba8, ba9, ba10, and ba46. the ventrolateral prefrontal cortex is composed of areas ba45, ba47, and ba44. the medial prefrontal cortex (mpfc) is composed of ba12, ba25, and anterior cingulate cortex: ba32, ba33, ba24. the ventral prefrontal cortex is composed of areas ba11, ba13, and ba14. (also see the definition of the orbitofrontal cortex.) the dorsolateral prefrontal cortex contains ba8, including the frontal eye fields. the ventrolateral prefrontal cortex contains ba45 which is part of broca's area. some researchers also include ba44 the other part of broca's area. interconnections the prefrontal cortex is highly interconnected with much of the brain, including extensive connections with other cortical, subcortical and brain stem sites. the dorsal prefrontal cortex is especially interconnected with brain regions involved with attention, cognition and action, while the ventral prefrontal cortex interconnects with brain regions involved with emotion. the prefrontal cortex also receives inputs from the brainstem arousal systems, and its function is particularly dependent on its neurochemical environment. thus, there is coordination between our state of arousal and our mental state. the interplay between the prefrontal cortex and socioemotional system of the brain is relevant for adolescent development, as proposed by the dual systems model. the medial prefrontal cortex has been implicated in the generation of slow-wave sleep (sws), and prefrontal atrophy has been linked to decreases in sws. prefrontal atrophy occurs naturally as individuals age, and it has been demonstrated that older adults experience impairments in memory consolidation as their medial prefrontal cortices degrade. in monkeys, significant atrophy has been found as a result of neuroleptic or antipsychotic psychiatric medication. in older adults, instead of being transferred and stored in the neocortex during sws, memories start to remain in the hippocampus where they were encoded, as evidenced by increased hippocampal activation compared to younger adults during recall tasks, when subjects learned word associations, slept, and then were asked to recall the learned words. the ventrolateral prefrontal cortex (vlpfc) has been implicated in various aspects of speech production and language comprehension. the vlpfc is richly connected to various regions of the brain including the lateral and medial temporal lobe, the superior temporal cortex, the infertemporal cortex, the perirhinal cortex, and the parahippoccampal cortex. these brain areas are implicated in memory retrieval and consolidation, language processing, and association of emotions. these connections allow the vlpfc to mediate explicit and implicit memory retrieval and integrate it with language stimulus to help plan coherent speech. in other words, choosing the correct words and staying “on topic” during conversation come from the vlpfc. function executive function the original studies of fuster and of goldman-rakic emphasized the fundamental ability of the prefrontal cortex to represent information not currently in the environment, and the central role of this function in creating the "mental sketch pad". goldman-rakic spoke of how this representational knowledge was used to intelligently guide thought, action, and emotion, including the inhibition of inappropriate thoughts, distractions, actions, and feelings. in this way, working memory can be seen as fundamental to attention and behavioral inhibition. fuster speaks of how this prefrontal ability allows the wedding of past to future, allowing both cross-temporal and cross-modal associations in the creation of goal-directed, perception-action cycles. this ability to represent underlies all other higher executive functions. shimamura proposed dynamic filtering theory to describe the role of the prefrontal cortex in executive functions. the prefrontal cortex is presumed to act as a high-level gating or filtering mechanism that enhances goal-directed activations and inhibits irrelevant activations. this filtering mechanism enables executive control at various levels of processing, including selecting, maintaining, updating, and rerouting activations. it has also been used to explain emotional regulation. miller and cohen proposed an integrative theory of prefrontal cortex function, that arises from the original work of goldman-rakic and fuster. the two theorize that “cognitive control stems from the active maintenance of patterns of activity in the prefrontal cortex that represents goals and means to achieve them. they provide bias signals to other brain structures whose net effect is to guide the flow of activity along neural pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task”. in essence, the two theorize that the prefrontal cortex guides the inputs and connections, which allows for cognitive control of our actions. the prefrontal cortex is of significant importance when top-down processing is needed. top-down processing by definition is when behavior is guided by internal states or intentions. according to the two, “the pfc is critical in situations when the mappings between sensory inputs, thoughts, and actions either are weakly established relative to other existing ones or are rapidly changing”. an example of this can be portrayed in the wisconsin card sorting test (wcst). subjects engaging in this task are instructed to sort cards according to the shape, color, or number of symbols appearing on them. the thought is that any given card can be associated with a number of actions and no single stimulus-response mapping will work. human subjects with pfc damage are able to sort the card in the initial simple tasks, but unable to do so as the rules of classification change. miller and cohen conclude that the implications of their theory can explain how much of a role the pfc has in guiding control of cognitive actions. in the researchers' own words, they claim that, “depending on their target of influence, representations in the pfc can function variously as attentional templates, rules, or goals by providing top-down bias signals to other parts of the brain that guide the flow of activity along the pathways needed to perform a task”. experimental data indicate a role for the prefrontal cortex in mediating normal sleep physiology, dreaming and sleep-deprivation phenomena. when analyzing and thinking about attributes of other individuals, the medial prefrontal cortex is activated, however, it is not activated when contemplating the characteristics of inanimate objects. studies using fmri have shown that the medial prefrontal cortex (mpfc), specifically the anterior medial prefrontal cortex (ampfc), may modulate mimicry behavior. neuroscientists are suggesting that social priming influences activity and processing in the ampfc, and that this area of the prefrontal cortex modulates mimicry responses and behavior. as of recent, researchers have used neuroimaging techniques to find that along with the basal ganglia, the prefrontal cortex is involved with learning exemplars, which is part of the exemplar theory, one of the three main ways our mind categorizes things. the exemplar theory states that we categorize judgements by comparing it to a similar past experience within our stored memories. a 2014 meta-analysis by professor nicole p.yuan from the university of arizona found that larger prefrontal cortex volume and greater pfc cortical thickness were associated with better executive performance. attention and memory lebedev et al. experiment that dissociated representation of spatial attention from representation of spatial memory in prefrontal cortex a widely accepted theory regarding the function of the brain's prefrontal cortex is that it serves as a store of short-term memory. this idea was first formulated by jacobsen, who reported in 1936 that damage to the primate prefrontal cortex caused short-term memory deficits. karl pribram and colleagues (1952) identified the part of the prefrontal cortex responsible for this deficit as area 46, also known as the dorsolateral prefrontal cortex (dlpfc).