Upgrade to remove ads
Executive function and working memory
Terms in this set (21)
What is executive function?
a set of processes needed to organize behavior to achieve a goal
Flexibility is vital
- relate current action to future goal
- how a particular step relates to overall goal (part to whole)
- change actions when conditions warrant
Processes of executive function
1) Working memory
- maintain, manipulate, update info needed to achieve goal
2) Selective attention
- represent information relevant to task (excitation)
- prevent representation of information irrelevant to task (inhibition)
- motor programming
- temporal sequencing
- put together set of actions/thoughts in correct order
4) Response monitoring
- error detection
- refine next action based on previous action
5) Decision making and conflict resolution
- between stimuli
- between responses
- between competing goals
Perception-action cycle (Fuster 2004)
Effects of prefrontal lesions in humans
Task switching, or set-shifting, is an executive function and a kind of cognitive flexibility that involves the ability to shift attention between one task and another.
1) Visual attention
2) Set Shifting
1) provide information about visual search speed, scanning, speed of processing, mental flexibility, as well as executive functioning.
2) detecting several cognitive impairments such as Alzheimer's disease and dementia.
ability to adopt a new rule
-tested by Wisconsin card sorting test
Wisconsin card sorting test
1) Set Shifting
Most common in frontal lobe lesions
Delayed response task
A series of lesion studies assessed the role of the hippocampus on retrospective memory. In the first delayed response task, nonhuman primates were shown two food wells. For the primates to get a reward, they had to remember which food well was baited. However, the primate had to retain the information about the two prospects until an apparatus was lowered and raised after a delay interval. The results showed that lesions to the hippocampus impaired performance on this task.
Prefrontal and parietal neural interactions
Dorsolateral prefrontal and posterior parietal cortex share reciprocal projections.
They also share nearly identical patterns of neuronal activation during performance of memory-guided saccades. To test the hypothesis that the reciprocal projections between parietal and prefrontal neurons may entrain their parallel activation, the present experiments have combined cortical cooling in one cortical area with single-unit recording in the other to more precisely determine the physiological interactions between the two during working memory performance.
Oculomotor delayed response task
-mean firing rates of 71% of the prefrontal neurons during ODR performance changed significantly when parietal cortex was cooled.
-data suggest that prefrontal and parietal neurons achieve matched activation during ODR performance through a symmetrical exchange of neuronal signals between them; in both cortical areas, neurons activated during the cue, delay, and also saccade epochs of the ODR task participate in reciprocal neurotransmission; and the output of each cortical area produces a mixture of excitatory and inhibitory drives within its target.
Regional activations during working memory (Schumacher 1996)
working memory maintenance and manipulation
Pet: Study, task vs rest
the "n-back" task in which subjects must decide for each letter in a series whether it matches the one presented n items back in the series.
Superior parietal, premotor cortex, posterior parietal, and dorsolateral prefrontal cortex active during working memory
Accomplished by varying the value of n. As n increased, subjects showed poorer behavioral performance as well as monotonically increasing magnitudes of brain activation in a large number of sites that together have been identified with verbal working-memory processes. By contrast, there was no reliable increase in activation in sites that are unrelated to working memory.
These results validate the use of parametric manipulation of task variables in neuroimaging research, and they converge with the subtraction paradigm used most often in neuroimaging. In addition, the data support a model of working memory that includes both storage and executive processes that recruit a network of brain areas, all of which are involved in task performance.
Prefrontal cortex and memory load (Braver et al)
Found same regions as Schumacher's study plus right caudate, bilateral inferior prefrontal gyrus
total amount of mental effort being used in the working memory based on the number of associations
fMRI results of memory load
health subjects produce one associate to a given picture for low selection items and the number of associates (active brain regions) increases with increased load
-prefrontal lesions imaired at high but not low selection
Stroop task experiment 1 and 2
Stroop task results
most trouble identifying the color of color letters (words says blue but its actually red)
Flanker vs Stroop
-both measured by response time and accuracy
-both involve selective attention (selecting compatible stimuli, inhibiting incompatible stimuli)
-Flanker relied on motor memory aspect along with motor laterality, also spatial memory
-Stroop relies more ons semantic memory
Working memory model (Baddeley and Hitch)
Phonological similarity effect
phonologically similar words in a short-term memory test are more difficult to recall than phonologically dissimilar words is a well-known phenomenon.
The effect of Articulatory suppresion
The effect of phonological similarity:
Lists of words that sound similar are more difficult to remember than words that sound different.
1) articulatory suppression:
Memory for verbal material is impaired when people are asked to say something irrelevant aloud. This is assumed to block the articulatory rehearsal process, thereby leaving memory traces in the phonological loop to decay.
2)Irrelevant sound effect:
With visually presented items, adults usually name and sub-vocally rehearse them, so the information is transferred from a visual to an auditory code. Articulatory suppression (irrelevant speech) prevents this transfer, and in that case the above mentioned effect of phonological similarity is erased for visually presented items
THIS SET IS OFTEN IN FOLDERS WITH...
Speech and Language
YOU MIGHT ALSO LIKE...
Individual Differences Lecture 16
Memory Pre Test
PSY 383 Exam 3
OTHER SETS BY THIS CREATOR