Transient Memories
- two types
(1) sensory memories
= brief, transient sensation of what you have just perceived when you have seen, heard , or tasted something
- visual sensory memory = temporary storage for information perceived by visual system
- iconic memory = rapidly defying visual sensory memory
- unlimited capacity
Transient Memories
- two types
(2) short-term memory
- limited in capacity
- limited to what you can pay attention to
Transient Memories
- Atkinson-Shiffrin Model
- three distinct memory stores
- serial position effect (primacy and regency effect)
(1) iconic (sensory) memory
(2) short-term memory (STM)
(3) long-term memory (LTM)
- serial position effect = pattern for what we typically remember
- primacy effect = beginning of the list: memory system has enough space to successfully transfer from short- to long-term memory by rehearsing the items
- regency effect = end of the list: items are available in short-term memory, having recently been seen
Transient Memories
- transfer from STM to LTM
- repeated rehearsal
- depth of processing
Working Memory
- Baddeley’s Working-Memory Model
- two independent short-term memory buffers
- Visuo-spatial sketchpad
- two independent short-term memory buffers
- Visuo-spatial sketchpad = holds visual and spatial images for manipulation
- limited capacity
- two sorts: spatial and visual
Working Memory
- Baddeley’s Working-Memory Model
- two independent short-term memory buffers
- phonological loop
- two independent short-term memory buffers
- phonological loop = same for auditory memories
- internal, unspoken speech used during rehearsal is key
- word-length effect
- subcomponents: phonological store (max. 2 seconds); articulatory rehearsal process
- phonological similarity effect
Working Memory
- Baddeley’s Working-Memory Model
- Central Executive
- central executive = monitors and manipulates both of these working-memory buffers
(1) determines when information is deposited in the storage buffers
(2) determines which buffer is selected for storage
(3) integrates and coordinates information between the two buffers
(4) provides a mechanism by which information held int he buffers can be inspected, transformed, and otherwise cognitively manipulated
Working Memory
- Tasks to assess working memory
- N-back test
e. g. 3456 –> “4”
- to be tested: control updating of working memory & buffers
- requirements: active maintainability of many kinds of items: continuous updating of working memory
Working Memory
- Tasks to assess working memory
- self-ordered memory tasks
- cards with different random order
- study working memory (good for comparison to monkeys)
Working Memory
- Tasks to assess working memory
- Tower of Hanoi
- great deal of manipulation of working memory (remember at least 3 things at all times)
Working Memory
- Tasks to assess working memory
- Stroop Task
- e.g. “green” written in red
Working Memory
- Tasks to assess working memory
- Wisconsin card sort test
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Brain Substrates
- prefrontal cortex
- prefrontal cortex (PFC) –> critical for working memory and executive control
- orbital prefrontal cortex
- medial prefrontal cortex
- lateral prefrontal cortex
- dorsolateral PFC
- ventrolateral PFC
Brain Substrates
- Behavioral Consequences of Frontal-Lobe Damage
- dysexecutive syndrome: disrupted ability to think, plan and organize
Brain Substrates
- Behavioral Consequences of Frontal-Lobe Damage
- Functional Neuroanatomy of PFC
- orbital and medial prefrontal cortex: not visible; involved in memory functions
- lateral prefrontal cortex: dorsolateral and ventrolateral PFC
Brain Substrates
- Frontal Brain Activity during Working-memory Tasks
- many PFC-neurons only fire during delay period when animals are required to maintain information about spatial location of object
- suggested that PFC holds information needed to make later response
- use of eye-tracking technology in monkeys to test
- “delay neurons” –> fire when animal was remembering the stimulus location
Brain Substrates
- Baddeley’s Model and PFC Anatomy
- Dorsolateral PFC = central executive (e.g. monitoring and manipulating stored information)
- Ventrolateral PFC
- Left Ventrolateral PFC = phonological loop
- anterior: semantic information
- posterior: phonological information
- Right Ventrolateral PFC = visuo-spatial sketchpad
- Left Ventrolateral PFC = phonological loop
Clinical Perspectives
- Shizophrenia
= characterized by hallucinations and delusions; bizarre and paranoid beliefs; also: disturbances in cognition and memory, especially in working memory and executive control (dorsolateral prefrontal cortex)
Clinical Perspectives
- ADHD
= great difficulty with executive-control processes such as planning, organizing their time, keeping attention focused on a task, and inhibiting responses to distracting stimuli
- dysfunction in prefrontal cortex and its comical and subcortical connections (including cerebellum and basal ganglia)
- medications: alter dopamine function in cortex
Fuster - Historical Paper –> Neuron Activity Related to Short-Term Memory
- Rhesus monkeys and single-unit recording
- evidence of a role of frontothalamic circuits in the attentive process involved in short-term memory
