Lecture11 Flashcards
What functions are the frontal lobes responsible for?
Supervisory/executive functions (working memory, inhibition, control, decision making, interacting with social & physical environment); personality & behaviour
What were some of the behavioural/personality changes expressed by Phineas Gage after a steel rod penetrated the front of his skull?;
What began occurring a few months before his death?
Fitful, irreverent & grossly profane; impatient & obstinate, yet capricious & vacillating, unable to settle on any future plans; irritable, often confused & unable to perform foreman duties;
Epileptic seizures
What symptoms were present in Arnold Pick’s life?;
What was found in his brain after he died?;
How is this feature different to Alzheimer’s disease?
Progressive loss of speech & dementia;
A shrinkage caused by brain cells dying in localised areas;
The atrophy is more generalised in AD
Describe the neuropathology associated with Pick’s disorder
Frontotemporal atrophy with “knife-like” thinning of the gyri in frontal lobes & temporal lobes; marked atrophy with ventricular dilation; swollen brain cells with abnormal tau protein inclusions
Describe the abnormal spontaneous behaviours associated with Frontotemporal dementia (FTD/Pick’s) during examination;
What other behavioural symptoms are present?
Inappropriate jocularity; echolalia (repeating examiner’s words); echopraxia (repeating examiner’s gestures); disinhibited approach or utilisation behaviours;
Unkempt; depressed in early stages; primitive reflexes such as grasp, suck, snout & toes
Clinically, during the first 2 years of Pick’s disease, psychiatric abnormalities related to the classic frontal lobe syndromes occur. What do these include?
Orbitofrontal dysfunction: aggressive & social inappropriateness (may steal or demonstrate obsessive or repetitive stereotyped behaviours) apathy & disinhibition; dorsomedial or dorsolateral frontal dysfunction: lack of concern, apathy, or decreased spontaneity
What speech & language abnormalities can occur with Pick’s disorder?;
Memory impairment is relatively…;
What kind of movement disorders can occur?
Verbal output is often non-fluent, with poor naming of objects (abnormalities often appear early & progress fast);
Less severe than speech/language & behavioural changes;
Akinesia, plastic rigidity, or paratonia on motor examination (involuntary resistance to movement) & perseveration (repetitive responses)
How was a frontal lobotomy performed?
Leucotome inserted 6 times into the patient’s brain with the cutting wire retracted; after each insertion the cutting wire was extruded & the leucotome rotated to cut out a core of tissue
What was reported in patients after receiving a frontal lobotomy?
Patients were “stimulus-bound”; they reacted to whatever was in front of them & didn’t respond to imaginary situations, rules or plans for the future; some gained significant weight &/or became sexually promiscuous; could not form/sustain goals; distracted by circumstances
Patient W.R (the man who lost his ego) suffered a seizure in his last year of college. Although PET & CT scans found no identifiable cause at the time, what did they find when a CT was re-done?;
What was the prognosis?;
What was W.R’s response?
An extremely large Astrocytoma transversing along the callosal fibres, invading extensively the lateral prefrontal cortex in the left hemisphere, & considerably in the right;
Death within a year;
Passive, detached, no rage, minimal anguish, general absence of concern; dissociation of what he could describe & feel emotionally
What are the most common types of brain tumours?;
What do they arise from?
Gliomas (40-50% of all brain tumours);
Any type of glial cells, hence gliomas, astrocytomas & oligodendrogliomas (they’re relatively fast growing)
What range of behaviours can occur from frontal lobe damage?
Apathy, irritability, aggression, poor social control, inappropriateness, poor planning & self-direction, distractibility, stimulus-bound (hyper-sensitive to stimuli in the environment)
On the face of it, unilateral damage to the lateral prefrontal cortex presents what kind of deficits?;
But behaviour is…
Mild, with intact intelligence & language;
Reflexive, elicited by environmental circumstances & purposeless: stimulus-driven; & cannot keep interpreting the environment based on previous knowledge; struggles with on-line manipulations
What does the lateral prefrontal cortex focus on?
Working memory; stimulus-driven behaviour (utilisation); concept formation; shifting concepts; temporal organisation; goal-oriented behaviour
How did Baddeley & Hitch come up with the Working Memory model?
Unitary STM concept was not enough to explain how information is maintained & worked on over short periods; limited capacity over the short term; performing mental operations (more than just rehearsal) on contents of store; contents may be new sensory info &/or retrieved info (can manipulate past experiences & reorganise)
On-line manipulation of information is conceptualised as what?
Working memory (e.g. reorganising alphanumeric orders)
In McCarthy et al.’s spatial vs. working memory task, what responses were recorded via fMRI scans in each task?;
What were the results?;
What does this suggest about the lateral prefrontal cortex?
Control colour task: red object appears; spatial working memory task: stimulus appears at a location previously used; same stimulus, only instructions/higher cognitive task differed (accessing previous experience)
Much greater activation in the lateral prefrontal cortex during the working memory task;
It is involved with concept formation, shifting & perseveration
Describe a “normal” performance on the Wisconsin Card Sorting Task;
How does a person with prefrontal cortical damage perform on this test?
When administrator changes the rules (i.e correct sorting category changes to shape, colour or number) they can shift to the new category
Impaired ability to “find” category &/or shift to new category; perseveration with same category even after changed conditions
What was found with the lateral prefrontal cortex & working memory in regards to the Wisconsin card sorting task?
Information must be integrated with information that was relevant in previous trials; subject must retain knowledge about the relevance of features & manipulate this information on-line
In a computerised version of the WCST, Konishi et al. found what about the function of the prefrontal cortex in regards to switching performance?
It inhibits dimension that is not relevant; dynamically sifts & filters through possible alternatives
In Konishi et al.’s WCST, more dimensions used in the task, led to greater activations of what?;
What area does this subserve?
Inferior frontal sulci in both hemispheres (larger activations with 3 dimensions rather than 1 or 2);
Concept formations & concept shifts
What is chronogenesis?
Temporal organisation & segregation of memory representations (the way we organise memories of life events)
Patients with frontal lobe lesions can perform well on recognition & recall of events but cannot…
Arrange the events in correct temporal order (recency judgement)
Jasper had a patient with frontal lobe lesions, arrange a sequence for cooking meals. Though she could remember the ingredients, what couldn’t she do?
Arrange her actions into a proper sequence, switch preparation from one dish to another, or mix up which ingredients belonged together; she couldn’t generate a plan to achieve a coherent goal
Shallice & Burgess had traumatic brain injury patients perform realistic day-to-day tasks, such as running errands (with a list - so no memory component). How did the patients perform?;
This study was assessing what?
Failed the tasks (went outside designated shopping area, failed to pay for item or to buy alternative when favourite was unavailable);
Goal-oriented behaviour
What is Duncan’s theory on goal-oriented behaviour?
We identify /select goal & develop appropriate subgoals; anticipate consequences; determine what is required to achieve subgoals
When selecting appropriate subgoals, it is necessary to…
Filter irrelevant information & keep eyes on the prize; select the best way to achieve a goal (evaluate); simultaneously accept/reject other options & plans of actions (e.g. to save for a holiday, cut out buying new clothes but keep paying rent)
The Anterior Cingulate Cortex was thought to be part of the…;
But has now shown to…
Limbic system (modulation of autonomic responses); Have attentional /monitoring functions
From where does the Anterior Cingulate Cortex receive its input?;
Where does it send its output?
From limbic structures, including amygdala, thalamus & striatum, as well as brainstem;
To prefrontal cortical areas
Corbetta et al. asked participants to selectively attend to a single visual feature, i.e. colour, shape, motion (passive), or to monitor changes in all 3 at the same time (divided attention). What differences in activity were found between conditions?
Passive - enhanced activity in feature-specific regions; divided attention - anterior cingulate cortex activation
In studies on Utilisation behaviour, with patients suffering frontal lobe damage, actions to individual objects are intact but…;
Wolpert et al. found that in contrast with alien/anarchic hand syndrome (where the action is disowned), the patient will…
They’re made inappropriately in the context of a particular task; irrelevant objects disrupt performance to relevant objects;
Justify the action; there is no perceived discrepancy between actions & intentions
What is a crucial deficit of utilisation behaviour?
Poor generation of intentions; actions are triggered by affordances in the environment; efference copy is generated, parietal lobe intact, action “feels” right
What is the Orbitofrontal cortex responsible for?;
What does it integrate?;
Changes in personality, as seen by Gage & W.R., are associated with damage in what regions?
Social & emotional judgement; social & emotional decision-making (choosing how to act);
Incoming info with pre-existing info about goals, values & current social situation;
Ventromedial prefrontal cortex & lateral-orbital prefrontal cortex
According to Damasio, the orbitofrontal cortex is involved with…;
His patient Elliot, who had a tumour invading the OBC bilaterally, showed what kind of behaviour?;
Post-surgically, what was his state?
Emotion, affect, rational thinking, underlying neurobiology; antisocial behaviours (stealing, violent outbursts)
Lack of concern for social rules; decreased social awareness & empathy;
Above normal intellect, but no schedule or motivation; initiated risky ventures against advice (couldn’t judge); couldn’t shift from mundane task; bankrupt (w/o concern)
In Bechara et al.’s gambling task, assessing anticipation of rewards & punishments by measuring skin conductance, what was found with patients suffering damage in the orbitofrontal cortex?;
Patients’ skin conductance was much lower than controls in all conditions, particularly in anticipatory condition (they didn’t care about receiving either reward or punishment)
Explain how patient J.S., previously quiet & withdrawn, with no psychiatric history, acquired sociopathy
After suffering right frontal trauma (including OBC), he displayed high levels of aggression, callous, disregard for others & lack of remorse
In Blair & Cipolotti’s study, how did patient J.S perform compared to other subjects on emotion/perception tasks?
This behaviour was attributed to an impaired ability to what?
Poor recognition of visually presented emotions (& reduced autonomic response); poor identification of social behaviour violations; lower GSR’s & disgust than controls; poor attribution of emotions, theory of mind & judgement of moral vs. social transgressions;
Generate expectations of negative reactions in others, thus suppressing inappropriate behaviour
