Executive functions
Furthermore, in their review, Alvarez and Emory state that:[6]The frontal lobes have multiple connections to cortical, subcortical and brain stem sites.[20] The executive system is thought to be heavily involved in handling novel situations outside the domain of some of our 'automatic' psychological processes that could be explained by the reproduction of learned schemas or set behaviors.[22][page needed] Executive functions are often invoked when it is necessary to override prepotent responses that might otherwise be automatically elicited by stimuli in the external environment.However, where such behavior conflicts with internal plans (such as having decided not to eat chocolate cake while on a diet), the executive functions might be engaged to inhibit that response.[23][page needed] Although research into the executive functions and their neural basis has increased markedly over recent years, the theoretical framework in which it is situated is not new.[26] The British neuropsychologist Tim Shallice similarly suggested that attention is regulated by a "supervisory system", which can override automatic responses in favour of scheduling behaviour on the basis of plans or intentions.[31] Inhibitory control and working memory are among the earliest executive functions to appear, with initial signs observed in infants, 7 to 12 months old.[29][30] During preadolescence, children display major increases in verbal working memory;[34] goal-directed behavior (with a potential spurt around 12 years of age);[35] response inhibition and selective attention;[36] and strategic planning and organizational skills.Changing one's behavioral response to meet a new goal or modify an objective is a higher level skill that requires a fusion of executive functions including self-regulation, and accessing prior knowledge and experiences.According to this model, the executive system of the human brain provides for the cross-temporal organization of behavior towards goals and the future and coordinates actions and strategies for everyday goal-directed tasks.Thus, executive function deficits pose serious problems for a person's ability to engage in self-regulation over time to attain their goals and anticipate and prepare for the future.[51] Yet another model of executive functions is a problem-solving framework where executive functions are considered a macroconstruct composed of subfunctions working in different phases to (a) represent a problem, (b) plan for a solution by selecting and ordering strategies, (c) maintain the strategies in short-term memory in order to perform them by certain rules, and then (d) evaluate the results with error detection and error correction.[59] This framework proposes four broad domains of volition, planning, purposive action, and effective performance as working together to accomplish global executive functioning needs.While this model may broadly appeal to clinicians and researchers to help identify and assess certain executive functioning components, it lacks a distinct theoretical basis and relatively few attempts at validation.[60] In 2001, Earl Miller and Jonathan Cohen published their article "An integrative theory of prefrontal cortex function", in which they argue that cognitive control is the primary function of the prefrontal cortex (PFC), and that control is implemented by increasing the gain of sensory or motor neurons that are engaged by task- or goal-relevant elements of the external environment.The aggregate effect of these bias signals is to guide the flow of neural activity along pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task.Miller and Cohen draw explicitly upon an earlier theory of visual attention that conceptualises perception of visual scenes in terms of competition among multiple representations – such as colors, individuals, or objects.According to Miller and Cohen, this selective attention mechanism is in fact just a special case of cognitive control – one in which the biasing occurs in the sensory domain.According to Miller and Cohen's model, the PFC can exert control over input (sensory) or output (response) neurons, as well as over assemblies involved in memory, or emotion.[63] A cornerstone of this theoretical framework is the understanding that individual differences in executive functions reflect both unity (i.e., common EF skills) and diversity of each component (e.g., shifting-specific).[73] Assessment of executive functions involves gathering data from several sources and synthesizing the information to look for trends and patterns across time and settings.The executive system has been traditionally quite hard to define, mainly due to what psychologist Paul W. Burgess calls a lack of "process-behaviour correspondence".They exhibited disorganized actions and strategies for everyday tasks (a group of behaviors now known as dysexecutive syndrome) although they seemed to perform normally when clinical or lab-based tests were used to assess more fundamental cognitive functions such as memory, learning, language, and reasoning.[citation needed] Other evidence from single-cell electrophysiology in monkeys implicates ventrolateral PFC (inferior prefrontal convexity) in the control of motor responses.Early studies employed event-related potentials to reveal that electrical brain responses recorded over left and right visual cortex are enhanced when the subject is instructed to attend to the appropriate (contralateral) side of space.[103] The advent of bloodflow-based neuroimaging techniques such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) has more recently permitted the demonstration that neural activity in a number of sensory regions, including color-, motion-, and face-responsive regions of visual cortex, is enhanced when subjects are directed to attend to that dimension of a stimulus, suggestive of gain control in sensory neocortex.[106] Indeed, the only direct evidence comes from studies in which a portion of frontal cortex is damaged, and a corresponding effect is observed far from the lesion site, in the responses of sensory neurons.Other methods for measuring connectivity between distant brain regions, such as correlation in the fMRI response, have yielded indirect evidence that the frontal cortex and sensory regions communicate during a variety of processes thought to engage executive functions, such as working memory,[109] but more research is required to establish how information flows between the PFC and the rest of the brain when executive functions are used.A growing body of research demonstrates that bilinguals might show advantages in executive functions, specifically inhibitory control and task switching.[118] The study of executive function in Parkinson's disease suggests subcortical areas such as the amygdala, hippocampus and basal ganglia are important in these processes.One widely cited review article[124] emphasizes the role of the medial part of the PFC in situations where executive functions are likely to be engaged – for example, where it is important to detect errors, identify situations where stimulus conflict may arise, make decisions under uncertainty, or when a reduced probability of obtaining favourable performance outcomes is detected.
Executive (government)Adaptive behaviorSelf-controlNeuropsychologyBrain regionsClinical neuropsychologyCognitive neuropsychologyCognitive neuroscienceDementiaHuman brainNeuroanatomyNeurophysiologyNeuropsychological assessmentNeuropsychological rehabilitationTraumatic brain injuryBrain functionsArousalAttentionConsciousnessDecision makingNatural languageLearningMemoryMotor coordinationPerceptionPlanningProblem solvingThoughtAlan BaddeleyArthur L. BentonDavid BohmAntonio DamasioPhineas GageNorman GeschwindElkhonon GoldbergPatricia Goldman-RakicDonald O. HebbKenneth HeilmanEric KandelEdith KaplanMuriel LezakBenjamin LibetRodolfo LlinásAlexander LuriaBrenda MilnerKarl H. PribramPasko RakicOliver SacksMark RosenzweigRoger W. SperryHans-Lukas TeuberHenry Molaison ("H.M.", patient)K.C. (patient)Benton Visual Retention TestContinuous Performance TaskHalstead-Reitan Neuropsychological BatteryHayling and Brixton testsLexical Decision TaskLuria-Nebraska neuropsychological batteryMini–mental state examinationRey–Osterrieth complex figureStroop TestWechsler Adult Intelligence ScaleWechsler Memory ScaleWisconsin Card Sorting Taskcognitive sciencecognitive processesbehaviorattentional controlcognitive inhibitioninhibitory controlworking memorycognitive flexibilityfluid intelligencereasoningproblem-solvingneuropsychological testsBehavior Rating Inventory of Executive Functionmore comprehensive assessmentstimulus controloperantclassical conditioningprefrontal cortexcaudate nucleussubthalamic nucleusaddictionattention deficit hyperactivity disorderautismcentral nervous system disordersrewarding stimulussensitivityspecificityNeuroimaginglesiondorsolateral prefrontal cortexshift setanterior cingulate cortexapathyabuliaakinetic mutismorbitofrontal cortexcerebellumventral tegmental areasubstantia nigracannabinoid receptor 1neocorticalposterior cingulateschemasDon NormanTim Shallicereinforcementchocolate cakeDonald BroadbentShiffrinselective attentionMichael PosnerJoaquin FusterTrevor RobbinsBob KnightDon Stussneuropsychologistshort-term memorymental arithmeticmyelinatedinhibitory mechanismstheory of mind