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Cognitive Neuropsychology II Cognitive Control

Terms in this set (43)

executive functions
complex control processes that are needed to optimize performance in situations that require coordination between a number of basic cognitive processes. Imagine it as a conductor of an orchestra.
Linked to the prefrontal cortex.
prefrontal cortex
Important for associations between actions and their consequences, reason, moral judgements, etc.
We will focus on the non-social functions such as devising rules and plans, stitching between tasks, manipulating information in working memory, avoiding habitual responses etc.
lateral prefrontal cortex
What focuses attention, selects what is noticed and is responsible for planning and decision-making?
brodmann's areas
Map of cortex, different numbers divided by different areas; Area 17- primary visual cortex, in occipital lobe
anterior cingulate cortex
This is the part of the brain responsible for error detection, anticipation of tasks, and modulation of emotional responses.

Monitoring in situations of response conflict and error detection.
Also evaluating response conflict - supressing the prepotent response.
ventro-lateral prefrontal cortex
related with rule changes following an incorrect response.
in left hemisphere:
retrieval and maintenance of semantic and/or linguistic information (also called Broca's area)
in right hemisphere:
retrieval and maintenance of visual and/or spatial information
dorso-lateral prefrontal cortex
related with associating feedback (right or wrong), this was interpreted as monitoring.
in left hemisphere:
Selecting a possible range of responses and suppressing inappropriate ones; manipulating the contents of working memory; shaping the response space
in right hemisphere:
Monitoring and checking of information held in conditions of uncertainty; vigilance and sustained attention
anterior prefrontal cortex
Multi-tasking; maintaining future intentions/goals whilst currently performing other tasks or sub-goals. (the medial portion has been implicated in "theory of mind")
situations requiring executive functions
(1) situations involving planning or decision making
(2) Situations involving error correction or trouble shooting
(3) situations where responses are not well-learned or contain novel sequences of actions
(4) Situations judged as dangerous or technically difficult
(5) situations that require overcoming of a strong habitual response or resisting remptation
tower of london task
a task that requires the participant to move beads from an initial position to a specific end-point
Patients with damage to the left anterior frontal lobe take significantly more moves, which implies that they perform by trial and error rather than planning their moves.
ecological validity
the extend to which a task relates to everyday situations outside of the laboratory
six-element-test
the patient is given six open-ended tasks to perform within a 15-minute period. Patients are instructed to attempt each task. However they will be unable to switch tasks, they spend too much time planning but never execute plans-
wisconsin card sorting
The shapes on the cards are different in color, quantity, and design. The person administering the test decides whether the cards are to be matched by color, design or quantity. The participant is then given a stack of additional cards and asked to match each one to one of the stimulus cards, thereby forming separate piles of cards for each. The participant is not told how to match the cards; however, he or she is told whether a particular match is right or wrong. During the course of the test the matching rules are changed and the time taken for the participant to learn the new rules, and the mistakes made during this learning process are analysed to arrive at a score

Patients with lesion of the prefrontal cortex often fail to correct errors that are pointed out to them and instead stick to a previously correct response (perseveration)
FAS-test
requires people to generate words (no names) with a specified letter in a one-minute period. Patients with left lateral frontal lesion show even here perseveration.
stroop test
If the word BLUE is printed in red ink and participants are asked to say the ink color ("red") they are slowed relative to a control condition, in which the printed word is not a color name or the congruent color name.
functional imaging and lesion studies suggest involvement of anterior cingulate cortex
crystallized intelligence
based on previously acquired knowledge
fluid intelligence
relies on the current ability to solve problems/ novelty, flexible thinking and problem solving

damage to prefrontal lobe results in significantly lower IQ scores.
common characteristics of executive functions
ability to override automatic behaviour in order to deal with novel situations, plan for the future rather than live for the moment.
the type of processing must be inherently flexible in order to cope with the changing tasks from moment to moment (infinite range of if-then type mappings)
executive functions have biasing influence (making a certain behavious more or less likely) rather than dictating to the rest of the brain.
different models to explain executive functions
the extend to which the model assumes that executive functions can be decomposed into several modular-like processes vs. executive functions construed as a more unitary idea
degree of specialization for different kinds of material (words vs. scenes), operations (manipulation vs. maintenance)
goldman-rakies working memory model
assumes a unitary executive, ie PFC not divided into seperate processes.
Assumes some division into spatial and object-based working memory, although recent research is inconsistent with this. Rao et al. (1997) report that neurons shift their responsiveness from object to location based n task demands irrespective of their location in the DLPFC or VLPFC.
petrides' theory of working memory
assumes division of the pfc into at least two seperate processes - maintenance and manipulation
DLPFC: manipulation and monitoring
VLPFC: maintain activity and retrieve information
self-ordered pointing task
participants are asked to point to a new object on each trial and thus maintaining a working memory for previously selected items and update this information
Patients with PFC damage are impaired at this (which does kind of support petrides theory only it doesn't)
revised SAS model
retains elements of the original model (i.e. biasing activation schemas) but decompose executive functions into several modular like processes
Shallice & Burgess suggest eight partially independent executive sub-processes
These different processes are grouped into three different stages: one for specifying a new schema, one for implementing, and one for monitoring the results of schema implementation
although this is controversial there is eviddence from brain lesions and fMRI to some degree of relative specialisation of the prefrontal cortex.
prospective memory
remember to do things in the future (e.g. to deliver something or to take medication)
integrative model
Like the original SAS-model assumes biasing signals that enable novel and non-automatic mappings to be set up between sensory inputs, internal states and response outputs.
But doesn't endorse modular-like decomposition of executive functions. allows for functional differences: e.g. emotional, social and appetitive stimuli may be harder to control and require a different mechanism. they argue that the pfc maintains the goals and rules rather than the information itself
not only workingmemory but also prospective memory
summary to the models
models differ in the extent to which they propse the number of specialised sub-routines, a single working memory or a network of associations that are reconfigured from task to task

they all assume that the pfc has a biasing influence on the more specialised routines in the brain, enables control over automatic/habitual responses.

the notion that executive functions may contain several distinct subprocesses implies different neural substrates within the PFC
monitoring
The process of relating information currently held in mind back to the task requirement. It is also a checking mechanism for whether retrieved and perceived information is valid.
sustained attention
retaining focus on the task requirements over a period of time.
n-back task
working memory task; the participant must decide whether the currently presented stimulus is the same as the one presented immediately before (1-back), or two items before (2-back), or three items before (3-back).
DLPFC activity only in 2- or 3-back judgements. Especially these conditions are associated with greater uncertainty and require more monitoring.
rule induction
patient is shown a sequence of cards and has to deduce a general rule from the way the colored circles change.
patients with left frontal lesions have difficulties with this task in general, they fail to deduce anything. patients with right frontal lesions fail to revert back to a different rule even if told to do so.
goal-oriented behaviour
in order to achieve a goal, we develop action plans (hierarchy of subgoals).
problems can easily arise because:
Filtering irrelevant information
Focussing on the goal
Selecting the best way to achieve a subgoal
according to duncan (1995) successful execution of an action plan requires:
Identification of the goal and developing subgoals
When choosing among the goals, consequences must be anticipated
Determining what is required to achieve the subgoals
financial planning task
the participant has to develope a financial plan for a family that wants to save money. They are presented with an overview of their spendings.
while a healthy participant focuses on the realistic reduction of costs,
frontal lobe patients suggests to lower annual renting cost even if told that family has to live somewhere.
This hints at some disability to shift their focus fom one subgoal of the action plan to another.
multitasking
carrying out multiple different tasks in succession & also maintaining future goals whilst dealing with current ones.
anterior PFC activation.
explanations for different models
there could be inte-species differences between humans and other primates
finding that a region is activated by many different tasks doesn't rule out functional specialisation
functional specialisation may be relative rather than absolute
It is not possible to find tasks that tap only executive functions or one supposed type of executive function
ERN
error-related negativity, 100ms after the production of a noticed incorrect response. central prefrontal electrodes.
dynamic filtering theory
model suggested by shimamura (2000) to explain cognitive control.
assumes four aspects - selecting, maintaining , updating , rerouting (ascending complexitiy)

neuronal basis: dynamic filtering mechanism in prefrontal cortex that gates transient representations of semantic associations to the goal

tested in high-filtering/low-filtering situations
updating
manipulating information that is currently operated on (e.g. ordering information).
rerouting
ability to switch from one cognitive process or response to another
task switching
discarding a previous schema and establishing a new one

possible contributions:

1)Deliberate retrieval from memory of the alternative goals and responses
2)previous schemas may be triggered automatically
3)supression of the old task set
4)setting up the new task set

studies with bilinguals indicate that its number 3 (medial frontal lobe is involved)
switch cost
the latency difference that occurs when multiple sources of information compete for attention and cognitive control is needed to filter the goal related information
task set
configuration of ones mental state (e.g. attention) to be in accordance with the specific operations demanded by the task.
eriksen-flanker task
measuring the effect of distractor inhbition and response conflict. 5 letters are presented the central one is the target letter, the 4 flankers are either response congruent or incongruent to the target letter
conflict effect
incongruent reaction time minus congruent reaction time
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