The Frontal lobes

Executive functions and Impulse control

MOTIVATION/EMOTION and the FRONTAL LOBES

Remember that the thalamus projects to both the amygdala ….and to sensory cortex areas.. Where it is eventually processed by the frontal lobes

The Dual Process theory

• 1. sensory event via sense mode pathways to THALAMUS

• 2. From Thalamus to Amygdala ( fast)

• 3. from Thalamus to cortex/Frontal lobes (slower)

• 4. Amygdala triggers “ automatic affective responses

• 5. Amygdala input to frontal lobes inhibits rational thought …..And may produce “cognitive bias

• 6. Frontal lobes project to Amygdala and may suppress affective impulses

The amygdala also projects to the frontal lobes mainly to the “Prefrontal cortex” …the frontal cortical areas found anterior to the 2nd and primary motor areas

The Amygdala also projects to the Anterior Cingulate cortex (ACC) of the frontal lobes…

(sometimes referred to as the “limbic lobe” )

The frontal lobes also project to amygdala

EVIDENCECortex Dampens Subcortical Affect

• sham rage—occurs following removal of the cerebral cortex from experimental animals..

• In Cats:– lashing of the tail, vigorous arching of the back, clawing and attempts to

– bite, and autonomic responses. It is called sham rage because unlike

– genuine rage ( or predatory aggression)

the rage occurs spontaneously or can be triggered by

mild tactile or other non-noxious stimuli.

Evidence that the frontal lobes Regulate Subcortical Affective

impulses• Phineas Gage- • Emotional lability

emotional outbursts• irrationality

(Deficits in emotional Impusle control)

Prefrontal lobotomy

The effects of this procedure varied considerably

Early treatment

Perhaps due to differences in procedure- two general syndromes associated with frontal lobotomy (as well as naturally incurred frontal lobe damage)

-Pseudopsychopathy- (indicates loss of regulatory functions)

• Immature impulsive behavior, aggressive outbursts, Inappropriate jocular affect , Poor judgment and insight , coarse language, promiscuity, general loss of social skills, euphoria, Emotional lability, Distractibility (see Phineas Gage, orbito-frontal cortex; see fronto-temporal dementia )

Pseudodepression – (loss of M&E influences of PFC)

– Apathy, indifference, loss of initiative, loss of libido (see ventromedial ACC)

Confabulation

• Patients with severe frontal lobe lesions tend to fabricate quick, impulsive answers to questions. Some responses may be quite fanciful and imaginative. The patient cannot inhibit a response in order to check its validity. This tendency to fabricate an answer is called confabulation.

• Confabulation and Reduplication Syndrome• Patients with severe frontal lobe lesions tend to fabricate quick, impulsive answers

to questions. Some responses may be quite fanciful and imaginative. The patient cannot inhibit a response in order to check its validity. For example, when asked, "How did you get to the hospital?", the patient may respond with an imaginative tale that has very little relationship to the truth. This tendency to fabricate an answer is called confabulation. It is most common among patients with basal forebrain lesions and among patients with additional impairment of memory ability.

• Another syndrome that is similar to confabulation is reduplication. Here, the patient with a frontal lobe lesion confabulates that the current environment, usually the hospital, is actually another place that is similar to the current setting but has a different name and location. The patient may even claim that the current hospital is a university dormitory or an apartment building. The confabulated place is always somewhere else and it is usually familiar to the patient, such as the hospital in the patient's home town. The patient will often maintain this confabulation even when confronted with salient, contradictory information.

Frontal Lobe Damage- Misc..

• Frontal lobe stroke

• Frontotemporal dementia

A seizure is usually defined as a sudden alteration of behavior due to a temporary change in the electrical functioning of the brain, in particular the outside rim of the brain called the cortex. Below you will find some of the symptoms people with epilepsy may experience before, during and after a seizure. Seizures can take on many different forms and seizures affect different people in different ways. It is not implied that every person with seizures will experience every symptom described below.

Seizures have a beginning, middle, and end When an individual is aware of the beginning, it may be thought of as a warning or aura. On the other

hand, an individual may not be aware of the beginning and therefore have no warning. Sometimes, the warning or aura is not followed by any other symptoms. It may be considered a

simple partial seizure by the doctor. The middle of the seizure may take several different forms. For people who have warnings, the aura

may simply continue or it may turn into a complex partial seizure or a convulsion. For those who do not have a warning, the seizure may continue as a complex partial seizure or it may evolve into a convulsion.

The end to a seizure represents a transition from the seizure back to the individual’s normal state. This period is referred to as the “post-ictal period” (an ictus is a seizure) and signifies the recovery period for the brain. It may last from seconds to minutes to hours, depending on several factors including which part(s) of the brain were affected by the seizure and whether the individual was on anti-seizure medication. If a person has a complex partial seizure or a convulsion, their level of awareness gradually improves during the post-ictal period, much like a person waking up from anesthesia after an operation. There are other symptoms that occur during the post-ictal period and are detailed below.

Frontal lobeSeizures Seizures 2

Frontal Lobe SyndromesFrontal lobe epileptic seizures

• likely to involve brief episodes of screaming, bicycling movements, or even movements suggestive of sexual activity.

FL epilepsy inter-ictal characteristics

• hebephrenic characteristics (i.e. emotional withdrawal and blunted effect).

Executive effects of Frontal Lobe Damage

-difficulty formulating common rules and goals. if a rule or goal is given to the patient there is great difficulty in using it

to guide behavior. ..perhaps related to social motivations/perseveration

• Actions are motivated by immediate gratification of simple impulses… Relates to circumstantiality

• dissociation between the discriminative and affective aspects of pain. When stuck with a pin, such a patient reports that it hurts, but it doesn't bother him.

“Executive Functions” particularly affected by damage to dorsal parts of the ACC

EXECUTIVE FUNCTIONS

Frontal Lobes and Emotion

The Anterior Cingulate Cortex (esp

ventromedial) may be critical in frontal generation of emotion

The Anterior Cingulate

Frontal Lobes and Emotion- The Anterior Cingulate Cortex

• neuroimaging studies have implicated the. the dorsal ACC has been considered critical for cognitive and motor control (Posner and DiGirolamo, 1998 ).

-whereas the the ventral ACC has been implicated in-

transient mood changes (Mayberg et al., 1999 ).

depression and anxiety disorders (Mayberg et al., 2000 ; Brody et al., 2001 )

perception of pain (Rainville et al., 1997 ).

• lesion of the ventral ACC - patients have been described as apathetic and

unconcerned when significant events occur, such as making mistakes

(Eslinger and Damasio, 1985 ; Rylander, 1947 ). 

Ventromedial frontal cortex

lesion of the ventral ACC

• - patients described as apathetic and

unconcerned when significant events occur, such as making mistakes (Eslinger and Damasio, 1985 ; Rylander, 1947 )…like

pseudodepression

ACC- and Self-reflection

• Moran et. al.

• subjects judged the personal relevance of personality characteristics that were

either favorable (e.g., "honest") or unfavorable (e.g., "lazy"), they found that distinct neural circuits in adjacent regions of the prefrontal cortex subserve cognitive and emotional aspects of self-reflection.

• When material is judged to be self-relevant, the emotional valence of the material was associated with activity in the ventral anterior cingulate.

The Frontal Poles (OrbitoFrontal cortex)

The Frontal Poles/ORIBITO-FRONTAL CORTEX

The frontopolar cortex (FPC), the most anterior part of the frontal lobes,

The FPC long-term mental plans Generation of new, possibly more rewarding, behavioral or cognitive sequences.

These areas have interconnections with the amygdala and hypothalamus.

Counterfactual processing -The consequence of a decision/behavior can lead to feelings such as: satisfaction, relief, or regret… evaluation of the potential outcomes of alternative decisions.

Testing the role of the orbito-frontal cortex in counterfactual reactions- a simple gambling task was used- subject’s choices were categorized in terms of their anticipated and actual emotional impact.

Normal subjects reported emotional responses consistent with counterfactual thinking;they chose to minimize future regret and learned from their emotional experience. (also associated with increased activity in the orbito-frontal regions)

Patients with orbitofrontal cortical lesions, however, did not report regret or anticipate negative consequences of their choices.

The Frontal Poles/ORIBITO-FRONTAL CORTEXcounterfactual processing/ Regret?

Damage to the orbito-frontal cortex? May partially account for the pseudopsychopathic syndrome

• “Like pseudopsychopathy”-Emotional disturbance most often results from lesion of the orbital frontal areas.

• superficial emotional expression like laughing, crying etc in situations inappropriate to the emotion. The patient usually has no awareness that their emotional response is incorrect or extreme.

When we interact with another person we create a mental model of how that persons thinks and feels. We are likely to have initial, quick intuitions about the person, which are then followed by slower, more reasoned judgments.

Both intuition and deliberation are influencedby emotional value judgments.

Von Economo neurons (VENs) are a recently evolved cell type which may be involved in the fast intuitive assessment of complex situations.

We propose that the VENs relay an output offronto-insular and anterior cingulate cortex to the parts of frontal and temporal cortex associated with deliberative judgments. The VENs emerge mainly after birth and increase in number until age 4 yrs.

VON ECONOMO NEURONS

VENs• ACC are activated when subjects view an image of a loved one compared with that of an

acquaintance, suggesting that there might be an involvement of these structures in bonding [15].

• areas are also active when subjects experience guilt, embarrassment and engage in deception [26–28].

• ACC are also active in humor (Watson and Allman,unpublished fMRI data),

• trust, empathy, and the discrimination

• of the mental states of others [25,29,30].

• VENs probably serve to relay output of the processing within ACC

• to other brain structures.

Other interesting links to frontal lobe functions

• Cotard’s syndrome

• Mirror Neurons

DRUG CRAVING

• An important factor that contributes to drug-seeking in addicted individuals is the dopamine input pathways that arise from midbrain structures such as the VTA

• Dopamine and the frontal lobes

Amygdala and the frontal lobes• Amygdala stimulation can have a direct effect on personality including

increasing social withdrawl and defensiveness (Cain, 1992) as well as increasing sensitivity to dopamine. PTSD

• These amygdala dopamine neurons project to frontal lobes and are believed to play an inhibitory role on neocortical information processing (Stevens, 1992), which in turn is important in selective attention.

• The limbic/emotional brain generally refers to amygdala, hippocampal formation, hypothalamus, thalamus, and nearby “paralimbic” cortex, such as the anterior cingulate cortex, orbitofrontal cortex insula, and temporal poles

• Given the role of aberrant, intrusive, emotional memory in PTSD symptomatology, the limbic brain defines an obvious target of investigation; however, evidence linking these structures to specific PTSD symptoms is just emerging.

PTSD Brain Activity

Frontal lobes and Pain

• There is the well-known suppression of pain sensations that occurs as an everyday event, but is more prominent during military battles. A person may be wounded seriously and not be aware of it, or he may suppress being aware of it during concentration on some other activity. Whether this sort of suppression is of cerebral cortical origin is unknown, but it could be.

• prefrontal lobotomy or lobectomy, results in a dissociation between the discriminative and affective aspects of pain. When stuck with a pin, such a patient reports that it hurts, but it doesn't bother him.

FRONTAL CORTEX• Empirical studies suggests that broadly speaking,

• preferences, drives and choices are respectively processed in the ventral, medial and lateral sector of the frontal lobes [1].