Introduction
Introduction
Anatomy
Function
Deficits
Assessment
Anatomy
Functions
Deficits
Assessment
Anatomy
Functions
Deficits
Supplementary Motor Area (SMA) Syndrome
Testing; Grasp Reflex
Anatomy
Functions
Assessment
Dorsolateral Prefrontal Cortex
Dysfunctions
Cognitive Estimates
Judgment
Working memory
Mental (cognitive) flexibility
Decision making
Metamemory
Fluid Intelligence
Motivation and drive
Planning
Motor Sequencing (programming)
Free Will
The Frontal Operculum
Anatomy
Orbitofrontal cortex
Anatomy
Functions, deficits, and assessment
Inhibitory Control
Self-control (response inhibition)
Environmental Autonomy
Imitation Behavior
Utilization Behavior
Environment-Dependency Syndrome
Prehension Behavior
Learning
Decision-making
Reversal Learning
Olfactory Information Processing
Emotional Regulation
Hedonic Processing
Decision-making
The Iowa Gambling Task
Trail-making test (TMT)
Intra-Extra Dimensional Set Shift (IED)
The Flanker Task
Anterior Cingulate Cortex
Anterior Cingulate Rough
The primary motor cortex is a key brain structure involved in the acquisition and performance of the skilled movement.
Kleim JA. Synaptic Mechanisms of Learning. In: Encyclopedia of Neuroscience. Elsevier Ltd; 2009:731-734. doi:10.1016/B978-008045046-9.01316-4
On the precentral gyrus just rostral to the central sulcus. Posteriorly bordered by the primary somatosensory cortex.
the primary motor cortex is part of the Broadman's Area four
It is part of Brodmann's area six and is located just anterior to the primary motor cortex.
It lies superficially on the lateral aspect of the cerebral hemisphere, occupying the middle and lateral portions of the prefrontal surface. Its corresponding Broadman’s areas area 46 (within the middle frontal gyrus) and area 9 (portions of the superior and middle frontal gyri) caudal to area forty-six.
Dysfunctions of the dorsolateral prefrontal cortex include the following:
To assess problem-solving hypothesis generation, it also correlates with crystallized and fluid intelligence, generativity, self-monitoring, and cognitive dysfunction in adults with schizophrenia. “What is the average human height”? “How many cities in the world are there?” See Gansler et al 2014.
No excellent tests exist for these functions other than observation. Patients can score high on the WAIS or other cognitive tests and still cannot behave appropriately. Acquired sociopathy can occur with individuals with orbitofrontal cortex injuries who may score highly on all cognitive measures and yet cannot hold a job, make, and maintain long-term personal relationships, and exercise judgment.
Actively and simultaneously holds multiple pieces of transitory information, received from sensory stimuli, in the mind for mental manipulation and processing. The dorsal dlPFC is involved in monitoring the information in the working memory. Researchers think ventral DLPFC to regulate the active encoding and retrieval of information stored in posterior cortical association regions based on selective judgments.
Verbal working memory (left DLPFC): Speak the following digits in the same order and ask the patient to reorder them ascendingly. 6,9,4,7 (to 4,6,7,9).
Visuospatial working memory (right DLPC): we test it formally tested with Corsi Block Test (formal test) in which a subject sees the tester touch a series of blocks, then the subject is to touch the blocks in the same order. N-back tasks are also often used to assess WM, although they require selective and sustained attention too. Digit span test does not require manipulation of the contents and is therefore not purely a test of the working memory, but of executive function.
The mental ability to switch between thinking about two different concepts, and to think about multiple concepts simultaneously or the readiness with which the person's concept system changes selectively in response to appropriate environmental stimuli. It is assessed by inviting the subject to expand the groups he has created on the original sorting task.
Task Switching or set-shifting: The ability to unconsciously shift attention between one task and another. Task switching allows a person to adapt to different situations rapidly and efficiently. Set is the preparation of neural resources for expected sensory input or motor response during executive performance. We commonly observe deficits in task switching in patients with Parkinson's disease and Autism spectrum. Most task-switching paradigms involve two tasks. For example, a letter is a vowel or consonant a number is even or odd, and pressing a key on the right or left, with each key mapped to one feature of each task (e.g., left might be for a consonant or an even number and right for a vowel or an odd number). The stimuli in most task-switching tasks are bivalent, they have a feature relevant to each of the two tasks, and the correct response for one task is incorrect for the other (e.g., for the stimulus “A2,” the correct response for the letter task would be to press right because A is a vowel, whereas the correct response for the number task would be to press left because 2 is an even number).
Dimensional Change Card Sort Test (DCCS): The simplest possible test of task switching. Stimuli are bivalent, and the correct response for one task is incorrect for the other, but only one switch occurs during the entire test. First, one is to sort all six cards by one dimension (color or shape), and then one is to sort all the cards according to the other dimension. Memory demands are intentionally minimized by an illustration at each response location of the features mapped to that response and by the experimenter reminding the child of the current sorting criterion on each trial. Children of 3 years can flawlessly sort by either color or shape but fail to switch even though they know the other dimension is now relevant and they know the rules for sorting by it. Errors seem to occur because of difficulty in inhibiting or overcoming what might be termed “attentional inertia,” the tendency to continue to focus attention on what had previously been relevant.
Cognitive Shifting: The mental process of consciously redirecting one's attention from one fixation to another. Deficits: Stuck-In-Set Perseveration (perseveration into a certain set) and Continuous Perseveration (to inappropriately pursue a behavior)
Wisconsin Card Sorting Task: Also used for set-shifting. Each card in this test can be sorted by color, shape, or number. The task for the participant is to deduce the correct sorting criterion based on feedback and to flexibly switch sorting rules whenever the experimenter gives feedback that the sorting criterion has changed. it is tested using Wisconsin Card Sorting Test, COWA tests. Patients with frontal lobe lesions have difficulties navigating non-routine situations.
Lexical/Verbal fluency (for mental flexibility) (2-4): The patient is asked to produce as many words as possible, in one minute, starting with F, then A, and then S. Proper nouns and previously used words with a different suffix are not accepted (inform the patient). Normal adults should be able to list fifteen words letters in one minute. Total FAS words > 30. For the elderly ten words, letter/minute is acceptable. Performance in verbal fluency tests show several consistent characteristics in both children and adults: There is a hyperbolic decline in the rate of production of novel items over the duration of the task. More typical category exemplars are produced with higher frequency (i.e. by more subjects), and earlier in lists, than less typical ones. Items are produced in bursts of semantically related words with the semantic version and phonetic with the phonetic version.
Categorical Fluency Tests: Include naming animals, fruits, and vegetables. Judges ability to generate categorical lists. Literal fluency tasks (like the naming words that begin with a letter) are unusual and require self-organized retrieval from semantic memory. Frontal lesions, regardless of side, tend to decrease verbal fluency. Left frontal lesions usually result in lower word production than right frontal lesions.
Both risky and moral decision making; when individuals must make moral decisions like how to distribute limited resources. Costs and benefits of alternative choices are of interest. When options for choosing alternatives are present, the DLPFC evokes a preference towards the most equitable option and suppresses the temptation to maximize personal gain.
Exerts executive control over the memory apparatus, for example, decides whether a retrieved memory is plausible for a context, does strategic searching of the memory store, and temporally orders memories. See Schmolke et al 2010.
Conceptualization, Abstract Thinking, Relational Reasoning, Logical Reasoning, Problem Solving.
“Ability to draw conclusions or conceptualize theoretical relationships among concepts (items or processes) in a way beyond their tangible characteristics.” Includes both inductive and deductive logical reasoning. Deficit: Concreteness i.e. Concrete interpretation of a concept involves a focus on the obvious characteristics e.g. when asked about the similarity in two (different) flowers, they will instead say both are red or round, etc. (which are both concrete properties) instead of categorizing them both as flowers.
Assessment: Check to compare against the patient’s educational background and baseline performance. Monitoring and individual’s daily functioning: The ability to complete complex tasks, resolve new situations as they arise, demonstrate adequate reasoning skills day-to-day.
Proverb interpretation (Hertler et al., 1978): Proverbs tap an individual’s ability to move from concrete sayings into abstract, metaphorical thought. The proverbs provided must be novel, otherwise, responses may be based on rote memory. A bird in hand is worth two in the bush. A drowning man will clutch at a straw.
Similarities: Asking a person to identify similarities between words assesses his or her ability to identify the broader conceptual relationships among words. Other neurological and neuropsychological conditions can negatively impact this task, such as aphasia. A table and a chair. A pen and a pencil. Ice and glass. We assess visually based abstract reasoning skills are often using category tasks, requiring a person to recognize conceptual categorical relationships among visual pictures. Pattern tasks can help assess an individual’s ability to identify symbolic relationships among items.
Patients with minor DLPFC damage display disinterest in their surroundings; they are deprived of spontaneity in language and behavior.
Deficits: avolition, amotivation. Severe damage to this region in a person also leads to the lack of motivation to do things for themselves and/or for others. Studies have associated impaired motivation with lesions of the anterior cingulate and dorsolateral prefrontal cortex.
The Apathetic-Abulic-Akinetic Syndrome (Chirchiglia et al., 2019): (Or pseudo-depression syndrome). Indifference, lethargy, lack of initiative, Inability to manifest emotions and reduced sexual interest, the Reduced capacity of organization and execution of complex behaviors, anticipation and planning, behavioral inconsistency.
Requires the ability to look ahead in time, generate hypotheses for future events, select relevant actions according to the context, and sequence the actions needed to carry out a specific goal.
ASSESSMENT: Is the patient able to make an appointment? Is he/she able to follow-up with the appointment? Is the patient able to recount current problems and the reason for the interview? Is there evidence of thought disorder?
Motor program was defined as “a set of muscle commands that are structured before a movement sequence begins, and that allows the sequence to be carried out uninfluenced by peripheral feedback” (Keele, 1968, p. 387). The word program denoted the set of commands within the central nervous system that allowed for such performance. Patients with frontal lobe lesions are impaired in tasks that require temporal organization, maintenance, and execution of successive actions. Motor programming involves the specification of time, space, and effector systems to be used for a particular action, to achieve a specific goal. People perform skilled actions every day, and many of these movements are quite complex and fast (e.g., writing, washing our hands), involving the coordination in space and time of many muscles and muscle groups.
Fist-Edge Palm test (Luria’s Three-Step test) (Umetsu et al., 2002; Weiner et al., 2011): Ask the patient to pay attention to your hand movements and then perform the fist, edge, palm movements five times in a series. Do not give verbal instructions while demonstrating. Then tell him to repeat the movements in the same sequence. Patients with some impairment cannot execute the “fist–palm–edge” series in the correct order. Patients who are severely impaired cannot learn the series at all. Patients may simplify the task (use two gestures instead of three) or show perseveration (repeating the same gesture). Helpful in distinguishing normal and MCI subjects from AD and FTD, but does not differentiate between FTD and AD. (Weiner et al., 2011) Patients without frontal lobe deficits may sometimes underperform on this test as well; probably because other brain areas are also participating in the task (Umetsu et al., 2002).
Alternating verbal sequences task: Ask the patient to copy a segment with alternating M's and N's. Perseveration may occur in patients with frontal lobe lesions.
Free will is an expression of individual freedom. It allows the human being to have and express own opinions as well as to respect those of others. Free will is related to the moral sense, a binomial which directs the individual towards a proper social conduct. The prefrontal dorsolateral syndrome is responsible for the reduction or abolition of free will.
The frontal operculum corresponds with Brodmann’s Areas 44 And 45, beginning at the anterior ramus of the lateral fissure and extends to the inferior portions of the precentral gyrus. It is part of the primary taste cortex [1]
Broca's area is a part of the dominant frontal operculum. It is the center for the expression of language.
Apart from expressive language function, the Broca's area also exerts control over other brain areas during an array of cognitive tasks. It may suddenly cease engagement in a task. It is partly responsible for the perception of taste as it is part of the primary taste cortex.
The following are the deficits that result from an injury to a part of the frontal operculum.
[1] The dorsal part of the anterior insula is the other part of it
Fuster JM defines the orbitofrontal cortex as the part of the prefrontal cortex that receives inputs from the magnocellular nucleus of the thalamus.
The ability to control one’s attention, behavior, thoughts, and/or emotions to override a strong internal predisposition or external lure, and instead do what’s more appropriate or needed. It has the following subcategories.
Interference control: Inhibitory control of attention (interference control at the level of perception). The ability to selectively attend, focusing on what we choose, and suppressing attention to other stimuli is also known by terms like elective or focused attention, attentional control or attentional inhibition, executive attention.
Assessment
Enquire if the patient faces any trouble with the ability to focus attention, especially in distractible environments, and whether there is any decline from a previous performance.
Formal testing
Cognitive Inhibition
Suppressing prepotent mental representations e.g., resisting extraneous or unwanted thoughts or memories, including intentional forgetting
Associated with lateral OFC, as assessed on reversal learning tasks.
Testing
Conflicting Instructions
This task assesses a patient's sensitivity to interference. When the verbal commands (Being told to “tap twice when I tap once”) conflict with sensory information (seeing the examiner tap twice and not once), deficits in behavioral self-regulation can be seen in patients with frontal lobe dysfunction. This task is similar to the Stroop Test. Patients with a frontal lobe lesion will usually fail to obey the verbal command and instead execute the chiropractic movements by imitating the examiner. Tell the patient: “Tap twice when I tap once. “To be sure that the patient has understood the instructions, do a series of three trials run first: 1-1-1. Tell the patient: “Tap once when I tap twice.” To ensure that the patient has understood the instructions, do a series of three trials to run first: 2-2-2. The examiner now performs the actual following series: 1-1-2-1-2-2-2-1-1-2
Go/No-Go Test (Iverson, 2011)
To assess
We ask the patient to make a response to one signal (the go signal) and not to respond to another signal (the no-go signal; non-targets; also called distractors or lures). This test is the reverse of conflicting instructions and should be performed only after it.
The subjects must now inhibit the response (”tap once when i tap twice. “) that we previously gave them (in the conflicting instructions task), for the same stimulus (seeing the examiner tap twice). The patient must now inhibit a response that was previously given to the same stimulus (i.e. - not tapping at all when the examiner taps twice).
Alternatively, previous responses or behaviors can interfere with subsequent behaviors within the context of an established set (recurrent perseveration). This type of perseveration is most common in aphasic patients, who repeat a previously given response to a subsequent item on a confrontation naming task. They have hypothesized this to represent a failure of the usual inhibition of memory traces. Recurrent perseveration seems sensitive to left hemisphere lesions, especially in the temporoparietal region.
Tell the patient: “Tap once when I tap once. “To be sure that the patient has understood the instructions, do a series of three trials run first: 1-1-1
Tell the patient: “Do not tap when I tap twice. “To be sure that the patient has understood the instruction, do a series of three trials run first: 2-2-2.
The examiner now performs the actual following series: 1-1-2-1-2-2-2-1-1-2
Scoring
Stroop Test
(Barbarotto et al., 1998; Scarpina et al., 2017)
It examines the ability of the patient to inhibit cognitive interference (sensitivity to interference). The subject/patient must say the color in which words are printed, AND NOT the words themselves, e.g., a bus may be printed in blue, or a door in red. This task is made even more challenging by presenting the name of colors printed in different colored ink (Stroop effect.) Here again, the task is to tell the color of the ink, NOT TO READ the word.
The Stroop Effect occurs when the processing of a stimulus feature impedes the concurrent processing of another attribute of the same stimulus
Because of impaired interference control, patients behave in unfamiliar surroundings as if they oversaw the situation and perform complex actions dictated not by their role, but by the environmental cues. Patterns of responses: Sensory stimuli can activate patterns of responses in these patients. These sensory stimuli and patterns of responses include:
The reproduction of gestures and utterances that the examiner makes in front of the patient without giving preliminary instructions.
Testing
The usage of an object under compulsion from the visual or visual-tactile presentation, by a patient, in an inappropriate situation. It is an extension of magnetic apraxia. Patients are compelled by the visual, visual-tactile presentation to grasp and use the object kept in front of them. The proposed mechanism is the suppression of the inhibitory effect of the frontal lobe on the parietal lobe.
Testing
Magnetic apraxia: Bilateral manual grasping behavior.
A stimulus-triggered behavior due to their inability to control interference from the environment. It is a more elaborate form of utilization behavior. As a result of impaired interference control, patients behave in unfamiliar surroundings as if they were in charge of the situation and perform complex actions dictated not by their role, but the environmental cues. A stimulus-triggered behavior due to their inability to control interference from the environment.
Prehension is the ability to reach and grasp. Prehension behavior refers to the tendency of the patients to display grasping behavior upon the sight or sensory perception of an object e.g. examiner’s hands may compel the patient to take them. Prehension is an object-oriented behavior that underlies many skilled actions of the hand. It is the key behavior that allows humans to change their environment. It continues to serve as a remarkable experimental test case for probing the cognitive architecture of goal-oriented action (in contrast to habit-based actions).
Testing
Tell the patient: “Do not take my hands.”—The examiner is seated in front of the patient. Place the patient’s hands palm up on his/her knees. Without saying anything or looking at the patient, the examiner brings his/her hands close to the patient’s hands and touches the palms of both the patient’s hands, to see if he/she will spontaneously take them. If the patient takes the hands, the examiner will try again after asking him/her: “Now, do not take my hands.”
Scoring (as in FAB)
The orbitofrontal cortex stores the reward value of primary as well as secondary reinforcers and punishers. This forms its basis for stimulus-reinforcement learning, including rapid reversal learning and extinction. Impaired decision-making is related to deficits in these domains.
Representation of rewards and punishers
Stimulus-Reinforcement Learning
The evaluation of multiple response options followed by the selection of the response that is considered optimal. It depends on emotion and feeling and correlates with reversal learning.
Deficits
Impairments in the decision-making process, seriously compromise the quality of decisions in daily life. There is an increased sensitivity to reward and reduced sensitivity to punishment. Delay-discounting, which also results from decision-making deficits refers to the preference for a small immediate reward over a larger but delayed reward. Impulsive behavior is a similar concept, that we define as the tendency to choose a small or inferior immediate reward over a larger delayed reward.
Testing
It's a shift from responding to a stimulus that is no longer rewarded, to a previously unrewarded stimulus. Studies have attributed impaired reversal learning to the loss of inhibitory control of affective responding.
The reversal deficit correlates with socially inappropriate behavior and decision making. Analyses correlate impaired reversal-learning with lesions in the inferior convexity.
Testing
There is some evidence for a dissociation of function within the orbitofrontal cortex, in that lesions to the inferior convexity produce the go-no-go and object reversal deficits, whereas damage to the caudal orbitofrontal cortex, area 13, produces the extinction deficit (Rosenkilde, 1979).
The two studies did not find any deficits in the reversal-learning task. From an anatomical perspective, an answer for this disparity could be the rough way of expressing the orbitofrontal lesion, for example using Brain MRI. Research reveals that impairment in the reversal-learning task is more correlated with the medial part of the orbitofrontal cortex, whereas the lateral part of the orbitofrontal cortex is more concerned with the perception of inappropriate social behavior and emotional regulation. Deficits in reversal learning might be linked with ‘behavioral disinhibition,’
Conscious olfactory perception i.e. the ability to discriminate between odors.
Deficits
Olfactory perceptual dysfunction i.e. an inability to discriminate between odors
Assessment
Enquire about the sense of smell
Testing
A ‘‘scratch-and-sniff’’ test that requires matching each of 40 different odors to different lists of 4 verbal descriptors.
This function is associated with the lateral orbitofrontal cortex (Blair 2000). It includes both suppression and a generation of emotion, perhaps because of differential mechanisms.
Suppression of negative emotions: Such as fear response, fear extinction, and suppression of fear generalization. Suppression of the amygdala is the underlying mechanism as patients with VLPFC lesions show increased amygdala activity.
Generation of negative emotions: Patients with VMPC lesions show blunting of affect and reduced physiological responsivity to stressful events. Specific damage to white matter and area-32 are suggested explanations.
The anterior cingulate cortex corresponds with Broadman Are 24. It is in the medial portion of the cortex, just superior to the corpus callosum.
Regulates motivation by modulating inhibitory input in the supplemental motor area, through its own stimuli which maintain wakefulness and alertness states.
See João RB et al 2018, and Miller et al 2007.
A feeling that a body part is separate from the rest of the body and has a mind of its own. The patient does not recognize the limb as one that he/she owns and believes it to be a foreign object which he cannot control. AHS can involve damage to the anterior cingulate gyrus, the medial prefrontal cortex, and the anterior corpus callosum when a patient has frontal AHS. The other type of AHS, callosal AHS, is due to an anterior callosal lesion and affects dominant hemisphere control. See Goldberg et, al. 1990.
It emphasises the learning of reward and punishment associations to guide ongoing decision-making. Healthy subjects learn to avoid risky card decks. High immediate rewards with a risk of occasional remarkably high punishment. They grow a preference for safe card decks. The immediate rewards are smaller, but there is a lower risk of punishment. Patients with bilateral damage to the ventromedial PFC do not acquire a preference for the safe decks on the Iowa Gambling Task but prefer the risky decks for the duration of the task. See Bichara et al 1990.
This test is widely used as a diagnostic tool for eliciting shifts between cognitive sets. The TMT consists of 2 parts. In part A (TMTA), subjects must connect twenty-five numbered circles, and in part B (TMTB), numbers (1-13) and letters (A-M) must be connected in alternating progression, from 1-A to M-13. The total score is the time in seconds spent to complete each part. A family of tasks that taps cognitive flexibility includes design fluency (also called the unusual uses task e.g., for example, how many uses you can think of for a table), verbal fluency, and category (or semantic) fluency.
It is a computerized analog of the Wisconsin Card Sorting Test and tests set-shifting. The extra-dimensional shift using the dorsolateral prefrontal cortex and reversal-learning.
the extra-dimensional reversal learning orbitofrontal cortex.
It requires selective attention. You are to attend to the centrally presented stimulus and ignore the flanking stimuli surrounding it. When the flanking stimuli are mapped to the opposite response from the center stimulus (incompatible trials). Subjects respond more slowly because of the need to exercise top-down control.