Working Memory and Cognitive Control (ch. 9)

Strong activation of DLPFC during:

- Retrieval of past memories - Remembering the source of past memories

Dorsolateral Prefrontal Cortex (DLPFC)

- Supports central executive function (manipulation) Supports higher-order executive-control functions such as monitoring and manipulating stored information, thus doing the job of Baddeley's central executive.

Identify the three main regions of the prefrontal cortex.

1) Orbital Prefrontal Cortex 2) Medial Prefrontal Cortex 3) Lateral Prefrontal Cortex -Lateral PFC further divided into 2 components: a) Dorsolateral prefrontal cortex (DLPFC) b) Ventrolateral Prefrontal cortex (VLPFC)

Describe the three basic memory components of the Atkinson and Shiffrin model of memory.

1) Sensory memory—where information automatically and rapidly decays 2) Short-term memory (STM)—where information can be maintained as long as it is rehearsed or consciously attended to. 3) Long-term memory (LTM)—where memories can be retained for long periods, possibly permanently, without requiring ongoing maintenance or conscious attention.

Which of the 3 PFC regions is most involved in working memory?

Lateral PFC

3 components of Working Memory (according to Baddeley)

Phonological loop (inner voice) Visuospatial sketchpad (inner eye) Central Executive (attention)

What are the 2 types of Transient memory?

Sensory memory Short-term memory (STM)

Ventrolateral Prefrontal Cortex (VLPFC)

Supports encoding and retrieval of information (including rehearsal for maintenance), performing as the visuospatial sketchpad and phonological rehearsal loop proposed by Baddeley - Supports storage - Supports active maintenance of auditory and visual information.

How can you measure the central executive's manipulation of working memory?

The manipulation and use of working memory for cognitive control can be measured through neuropsychological tests that assess such function as controlled updating of short-term memory, setting goals & planning, task switching, and stimulus attention & response inhibition.

Short-term memory

a temporary memory that is maintained through active rehearsal. •Multimodal (general for senses) •Small capacity •Quick decay (<1 min) and over-writing •Rehearsal - preserves info in STM •Transfer to/from LTM

Phonological loop (inner voice)

an auditory memory maintained by internal (subvocal) speech rehearsal. ➢ Stores about 2 s of auditory information ➢ Rehearsal is primarily directed at this component. ➢ Seems to literally be a "hearing" in the mind: o Word-length effect: less capacity to memorize lists of multi-syllable words compared to single-syllable words o Those who speak faster can rehearse longer lists of words

Prefrontal Cortex (PFC)

essential for working memory & executive control

Visuospatial sketchpad (inner eye)

holds visual and spatial images for manipulation. ➢ Delayed Non-Matching to Sample Task o Requires visual memory of object to be held in mind during short delay - a function of the visuospatial sketchpad o With short delays, the task can be used to assess working memory. With longer delays, the same task has been used to study LTM.

Transient memory

nonpermanent memory that lasts seconds or minutes.

Cognitive Control required for switching between tasks

o In the Wisconsin Card Sorting Test: Patients try to learn a rule governing the sorting of cards. After they catch on, however, the rule is changed, requiring an updating of memory and behavior.

Long-term memory

permanent, or near-permanent, storage of memory that lasts beyond a period of conscious attention.

Working Memory

the active maintenance and manipulation of STM.

Visual Sensory Memory

the initial temporary storage for information perceived by the visual system. ***also called "iconic memory"***

Cognitive Control

the manipulation and application of working memory for planning, task switching, attention, stimulus selection, and the inhibition of inappropriate reflexive behaviors.

Central Executive (attention)

the working part of the mind that monitors and manipulates the two working memory buffers ➢ Exerts cognitive control over behavior; providing complex organization in response to environmental demands ➢ The defining activity of the central executive is the manipulation of remembered information. ➢ Researchers use a variety of tasks to study central executive function... o Self-ordered memory task: At each step, choose an item not yet selected; this requires monitoring of memory for each prior step. ➢ The central executive also sets goals, makes plans, and monitors completion. ➢ The central executive also plays a role in selecting appropriate behaviors and inhibiting inappropriate behaviors.

Describe the relationship between schizophrenia and prefrontal cortical dysfunction, including how dopamine is involved.

• Schizophrenia affects many behaviors and many brain regions, but two prominent symptoms include: - Poor working memory, especially tasks involving central executive function (manipulation) - Altered frontal lobe function, especially in the DLPFC - Evidence suggests that DLPFC is dysfunctional in schizophrenia patients; however, functions in the VLPFC seem relatively unimpaired. • Some evidences suggest that deficits in working memory and executive control found in schizophrenia may be linked to deficiencies in cortical dopamine processing. - Dopamine—is a neuromodulator that alters neuron-to-neuron communication, and most pharmacological treatments for schizophrenia work by altering the transmission of dopamine. - Genetic mutations affecting dopamine activity in the PFC are related to the emergence of the cognitive deficits seen in schizophrenia.

Describe the evidence of frontal lobe involvement in working memory tasks. (pictures on study guide)

• Ventrolateral PFC supports active maintenance of auditory (left) and visual (right) information. - Brain activity in self-ordered memory task using words (left) vs. images (right) - each selectively activates one side of PFC. • Neurons of the DLPFC fire while memories are being maintained in working memory. - Goldman-Rakic's delayed-response eye-gaze task - If delay neurons don't maintain activity throughout delay, errors usually occur! - Different delay neurons seem to encode different memory locations. - Imaging studies suggest human DLPFC also shows delay-specific activity during working memory tasks.

Describe Sperling's classic study of iconic memory.

•Sperling Task = three rows of four letters are presented in a visual array, he then played one of three tones and had - High tone = highest row - Mid tone = middle row - Low tone = lowest row ➢ Suggests that sensory storage holds a complete snapshot of the world but that it fades rapidly.

Describe several ways in which the central executive is able to manipulate the content of the working memory.

➢ Switching between tasks also requires cognitive control. o In the Wisconsin Card Sorting Test: • Patients try to learn a rule governing the sorting of cards. • After they catch on, however, the rule is changed, requiring an updating of memory and behavior. ➢ In the Stroop task, participants name the color of the ink used to print a set of words. **Tables on slides/study guide**

Sensory Memory

Brief, transient sensations of what has just been perceived when someone sees, hears, or tastes something. •One for each sense •Very large storage •Extremely rapid decay (~1s) and rapidly over-written by new incoming sensory information •Transfers to STM

Explain how prefrontal cortical dysfunction can contribute to the symptoms of attention-deficit/hyperactivity disorder.

Difficulties with: - Planning, organizing time - Keeping attention focused on a task - Inhibiting response to distracting stimuli May involve dysfunction in PFC cortical and subcortical connections, including cerebellum and basal ganglia. •Children with ADHD may have smaller right PFC •Genes associated with ADHD may be involved in dopamine regulation in the brain. •People with ADHD show deficits in mental calculations that require use of working memory. •Neuroimaging of people with ADHD indicates that they have a smaller PFC as well as noisy input signals from the basal ganglia that prevent the basal ganglia from accurately indicating what is or is not important to attend to.

Describe common behavioral and cognitive consequences of frontal lobe damage.

Humans with frontal cortex damage often have dysexecutive syndrome, a decrease in working memory and executive function. This causes problems both in real life and during psychiatric evaluation. Loss of ability to plan and to organize Deficits on all of working-memory and cognitive control-tasks. In animal models, lesions to the prefrontal cortex produce similar disruptions of short-term memory. Subsequent work has shown that the lateral PFC seems to be most involved in working memory and executive function ...

Describe the relationship between working memory and intelligence.

Intelligence - capacity to learn, reason, and understand. - What, specifically, is it that makes someone intelligent? - One possibility: excellent working memory function •Evidence suggests that general intelligence appears to be associated with a strong working memory, especially the control and manipulation of larger numbers of rules, concepts, goals, and ideas.