Monday, 21 November 2011

Cognitive Neuropsychology - Blog 8 - Frontal Lobes

As outlined by (Martin, 2006) the frontal lobes are the most recently developed out of the four lobes (Occipital lobe, temporal cortex, parietal cortex & the frontal lobes) and hold approximately 1/3 of the cerebral cortex. The frontal lobes are split into the 'orbito-frontal cortex' which is responsible for decision making and behavioural self regulation and the 'dorso-lateral region' which is responsible for cognitive & executive functioning, working memory and attention. The frontal lobes have been described as being the leader and are massively connected to other brain regions suggesting that the frontal lobes play a big part in the communication to the rest of the brain and support the notion that it is the master brain region. The frontal lobe is responsible for most types of our behaviour such as social behaviour, personality and motor movement and its roles include; engaging in abstract thought, planning and organisation, inhibiting inappropriate social and emotional responses. But more specifically the frontal lobes are involved in; working memory, encoding and retrieval of information, motor movement, attention and executive functions. Damage to the frontal lobes can destruct executive functioning which Banich (2009) said is vital to be able to live an independent life. A great example of this is the story of Phineas Gage who suffered major personality changes after a lateralization to his left frontal area (Damasio etal, 1994). Evidence shows that the frontal lobes play a crucial and perhaps master role in the brain, therefore damage to this area of the brain could consequently cause the inhibitoriest disorders. Many tests can be performed to test whether a patient has frontal lobe damage; the most frequently used test is the Wisconsin card sorting task where an examiner will change the rules without informing the patient and the patient will not adapt to this but will continue using the old and now inappropriate rule to sort out the cards.

Notes from article - Executive function: The search for an integrated account.

- Brian damage can damage the frontal lobes which in turn can damage executive functioning which is said to be required to live an independent life.

Banich (2009) suggests that executive functioning is necessary to 'effortfully guide behaviour toward a goal' and is especially needed for nonroutine situations. Executive function is sad to be required for; prioritising, sequencing behaviour, inhibiting familiar or stereotyped behaviours, creating and maintaining an idea, switching between task goals, decision making and categorizing.

- Executive functioning covers a wide amount of skills so there is not one general test but many different ways to test executive functioning.

- The Wisconsin card sorting test is most frequently used. This involves the participant learning a rule and then the examiner will change the rule without telling the participant. Patients with frontal lobe damage will still try and sort the cards out using the old and inappropriate rule.

- Stroop task (Decisions made on task relevant information when faced with distracting information.) the task involves identifying a word's colour and ignoring the word. Executive functioning is needed here because word reading is automatic so it's needed to over-ride this automatic response and instead name the colour.

- Many psychiatric illnesses involve executive functioning these are; schizophrenia, bipolar disorder, depression and attention deficit hyperactivity disorder.

-There seems to be little knowledge about how the frontal lobes support executive functioning although it is clear that damage to the frontal lobes is associated with executive functioning. Therefore making this a hard problem to prevent or treat.

Notes from lecture

- Wisconsin card sorting task - needs a shift in strategy after an unexpected rule change. Patients with lateral prefrontal cortex damage show 'perseveration'

Frontal lobes function (tests)

- Error correction & trouble shooting (entails sorting cards by shape, colour or numbers and then changing the rules.

Executive functions of the frontal lobes

Divided attention, sustained attention, processing speed, initiation, sequencing, self-shifting, cognitive flexibility & planning.

-Important for planning & controlling behaviour.

-Frontal lobes are needed to enhance performance in situations that involve coordination between a series of cognitive processes.

- It is not domain specific but is more of a supervisory role to memory, perception and language.

- The frontal lobes are linked to prefrontal cortex.

- Five general situations that require the frontal lobes executive functions as stated by Norman & Shallice (1986) are;

- Planning or decision making
-Error correction or trouble shooting
-When responses are not well learned or contain novel sequences of actions
-Situations that are judged to be dangerous or technically difficult
- Also needed when overcoming a strong habitual response or resisting temptation.

What areas do what?

- Lateral prefrontal cortex = working memory.
- Ventromedial zone = emotions & decision making
- Anterior cingulate (ACC) = monitoring behaviour (conflict & error detection).

(ACC) Anterior cingulate cortex

- Is vital for reward, anticipation, decision-making, empathy and emotion.
- Dorsal ACC is related to rational cognition & ventral is related to emotional cognition.

- OCD sufferers have high ACC activation.

- Depression can be as a result from low ACC activity.

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