Executive functions

Clinic

• Executive functions = Executive function + Cognitive control
• They are a set of cognitive processes that are necessary for the cognitive control of behavior: selecting and successfully monitoring behaviors that facilitate the attainment of chosen goals.

Types

Attentional control

• It colloquially referred to as concentration, refers to an individual's capacity to choose what they pay attention to and what they ignore.
• It is also known as endogenous attention or executive attention.
• Attentional control can be described as an individual's ability to concentrate.
• Primarily mediated by the frontal areas of the brain including the anterior cingulate cortex,
• It is thought to be closely related to other executive functions such as working memory.

• Low attentional control is more common among those with ADHD
• Also low attentional control is common in individuals with schizophrenia and  Alzheimer's disease, those with social anxiety, trait anxiety stroke. Individuals also respond quicker, and have better overall executive control when they have low levels of anxiety and depression.
• Attention problems are also characteristic of anxiety disorders like PTSD.

Cognitive inhibition

• It refers to the mind's ability to tune out stimuli that are irrelevant to the task/process at hand or to the mind's current state.
• Patients with OCD can experience the effects of reduced cognitive inhibition.
• Suicidal behavior may also be related to cognitive inhibition impairment.
• In ADHD, there is an impaired cognitive inhibition ability and find it difficult to suppress irrelevant stimuli.

Inhibitory control

• Also known as response inhibition, is a cognitive process – and, more specifically, an executive function – that permits an individual to inhibit their impulses and natural, habitual, or dominant behavioral responses to stimuli (a.k.a. prepotent responses) in order to select a more appropriate behavior that is consistent with completing their goals.
• Self-control is an important aspect of inhibitory control
• PFC, caudate nucleus, and subthalamic nucleus are known to regulate inhibitory control cognition.
• Inhibitory control is impaired in both addiction and ADHD

Working memory

• It s a cognitive system with a limited capacity that can hold information temporarily.
• It is important for reasoning and the guidance of decision-making and behavior.
• Working memory is often used synonymously with short-term memory, but some theorists consider the two forms of memory distinct, assuming that working memory allows for the manipulation of stored information, whereas short-term memory only refers to the short-term storage of information.
• ADHD arise from a primary deficit in a specific executive function (EF) domain such as working memory, response inhibition or a more general weakness in executive control.
• Patients with Parkinson's show signs of a reduced verbal function of working memory.
• As Alzheimer's disease becomes more serious, less working memory functions. In addition to deficits in episodic memory, Alzheimer’s disease is associated with impairments in visual short-term memory, assessed using delayed reproduction tasks.

Cognitive flexibility

• Cognitive flexibility is an intrinsic property of a cognitive system often associated with the mental ability to adjust its activity and content, switch between different task rules and corresponding behavioral responses, maintain multiple concepts simultaneously and shift internal attention between them.
• Certain conditions such as OCD are associated with reduced cognitive flexibility.
• Cognitive flexibility is a vital component of learning, deficits in this area might have other implications.
• These regions include the prefrontal cortex (PFC), basal ganglia, anterior cingulate cortex (ACC), and posterior parietal cortex (PPC).

Higher-order executive functions

• They require the simultaneous use of multiple basic executive functions and include planning and fluid intelligence (e.g., reasoning and problem-solving).

Many people with autism have difficulty with executive functioning. They may have trouble with certain skills like planning, staying organized, sequencing information, and self-regulating emotions. Some people pay attention to minor details, but have trouble seeing how these details fit into a bigger picture.

Neuroanatomy

Neuroimaging and lesion studies have identified the functions which are most often associated with the particular regions of the prefrontal cortex and associated areas.

• The dorsolateral prefrontal cortex (DLPFC) is involved with "on-line" processing of information such as integrating different dimensions of cognition and behavior. As such, this area has been found to be associated with verbal and design fluency, ability to maintain and shift set, planning, response inhibition, working memory, organisational skills, reasoning, problem-solving, and abstract thinking.Side view of the brain, illustrating dorsolateral prefrontal and orbitofrontal cortex

• The anterior cingulate cortex (ACC) is involved in emotional drives, experience and integration. Associated cognitive functions include inhibition of inappropriate responses, decision making and motivated behaviors. Lesions in this area can lead to low drive states such as apathy, abulia or akinetic mutism and may also result in low drive states for such basic needs as food or drink and possibly decreased interest in social or vocational activities and sex.
• The orbitofrontal cortex (OFC) plays a key role in impulse control, maintenance of set, monitoring ongoing behavior and socially appropriate behaviors. The orbitofrontal cortex also has roles in representing the value of rewards based on sensory stimuli and evaluating subjective emotional experiences. Lesions can cause disinhibition, impulsivity, aggressive outbursts, sexual promiscuity and antisocial behavior.

The cerebellum also appears to be involved in mediating certain executive functions, as do the ventral tegmental area and the substantia nigra.