The Neuropsychology of Memory

Milton J. Dehn, Ed.D., NCSPSchoolhouse Educational Services

April 2015

Notice of Copyright 2015

This PowerPoint presentation and accompanying materials are copyrighted by Milton J. Dehn and Schoolhouse Educational Services, LLC. The PowerPoint and materials are not to be reprinted, copied, presented, or electronically disseminated without written permission. To obtain permission, email milt@psychprocesses.com.

Workshop Information Sources

1. Working Memory and Academic Learning2. Long-Term Memory Problems in Children3. Essentials of Working Memory Assessment4. Working Memory in the Classroom5. Essentials of Processing Assessment, 2nd Ed.6. www.psychprocesses.com7. www.SchoolhouseEducationalServices.com8. Presenter Contact: milt@psychprocesses.com

Essentials of Working Memory

Working Memory Definition

1. ST retention + processing = WM2. “WM: the limited capacity to retain

information while simultaneously manipulating the same or other information for a short period of time”

3. Keeping information in mind from moment to moment

4. STM is part of WM; WM “manages” STM as needed

WM Capacity

1. STM adult span of 7; Digit span of 80?2. WM limit of 4 “chunks”3. Can be as little as one chunk in children4. Processing & storage use same WM resource5. Duration affected by rehearsal & amount of

interference 6. See ABC News Chimps vs Humans

Dehn’s Integrated Model of WMIntegrated Model of Working Memory

Verbal WM

Executive WM

Visual-spatial

WM

Active Verbal LTM

Visual-spatial STM

Phono-logical STM

Active Visual LTM

The Big Three Executive WM Processes

1. Inhibiting: Suppressing distractors and interference

2. Shifting: Alternating between different processing tasks or between processing and storage (rehearsal)

3. Updating: Continual replacement of no longer relevant information with current information

Activated LTM

1. Recently activated LTM representations2. WM works with these, going back and forth3. Up to 20 at a time4. Effectively expands capacity of WM because

these are not stored in STM/WM5. Is part of verbal and visual-spatial WM6. WM may draw from these more than STM7. Problem: No way to easily assess this

Working Memory and RelatedCognitive Processes

Should be considered when WM is deficient:1. Attention2. Executive functions3. Fluid Reasoning4. Language5. Long-term memory6. Processing speed7. Phonological processing

What WM and AttentionHave in Common

1. Both are in dorsolateral prefrontal cortex2. Both part of general executive functions3. Both involve controlled attention4. Inhibition deficit underlies both ADHD and WM5. Both respond to Ritalin6. Problems manifest in similar ways7. When a student has a WM deficit, the number

one thing reported by teachers is that the student has an attention problem

WM and Attention

1. The control of attention is part of WM2. Paying attention is a necessary but

insufficient condition for processing and retention in STM and WM

3. If child is paying attention and still can’t remember in the moment, it’s probably WM

4. Attention problems diminish WM performance in a normal WM

WM vs ADHD

1. The majority with ADHD have a WM problem2. ADHD behavior issues have little to do with

WM, except for poor decision-making3. Attention involves arousal & motor inhibition4. WM deficit closely related to Inattentive

ADHD, not Hyperactive/Impulsive type5. ADHD involves mainly visuospatial WM6. Divided attention closest to WM7. As WM load increases, hyperactivity increases

Neuroanatomy

Occipital Lobe

1. Dedicated to vision and visual-spatial processing

2. Receives sensory data from the thalamus3. Visual and spatial processing are separate4. Dorsal stream (upper) sends spatial

information to parietal lobe5. Ventral stream (lower) sends visual

information to temporal lobe

Temporal Lobe

1. Auditory processing2. Long-term memory processing in the

hippocampus3. Some visual processing4. Semantic memory storage

Parietal Lobe

1. Integrates sensory information2. Language processing3. Phonological processing

Frontal Lobe

1. The “output” lobe; others are input2. Executive functions---prefrontal cortex3. Working memory---prefrontal cortex4. Attentional control---prefrontal cortex5. Fluid reasoning6. Fine motor7. Oral expression8. No storage of long-term memories

Prefrontal Cortex Image

Brain Lobes and STM & WM

1. Frontal (Dorsolateral Prefrontal Cortex): Executive WM

2. Temporal: Episodic WM (especially during LTM encoding and retrieval)

3. Parietal Lobes: Phonological STM and Verbal WM in language processing areas

4. Occipital Lobes: Visuospatial STM and WM

Neuropsychology of WM

“working memory can be viewed as neither a unitary nor a dedicated system. Thus, working memory is not localized to a single brain region but probably is an emergent property of the functional interactions between the PFC and the rest of the brain” (D’Esposito, 2007)

WM Neurological Basis

1. Individual differences in WM capacity are correlated with the structural integrity of white matter pathways connecting domain general regions with the fronto-parietal network

2. Thus, WM is related to integrity (strength) and extent of myelinated axons

3. WM training increases the integrity of white matter (Takeuchi et al., 2010)

Phonological STM and Verbal WM

1. Left-hemisphere inferior parietal areas2. Brodmann’s area 40 in parietal lobe is the

storage area; Brodmann’s is involved in phonological processing; part of #3 below

3. Supramarginal gyrus in parietal lobe is also involved; supramarginal gyrus is involved in language processing

4. Broca’s area (language function) in inferior left frontal lobe is subvocal rehearsal area

Visuospatial STM and WM

1. Right hemisphere2. Occipital lobe3. Inferior frontal areas4. Visual is occipital5. Spatial is more parietal (dorsal stream)

Other Brain Involvement in General WM

1. Striatum: part of the forebrain and the basal ganglia system. Mainly involved with planning movement.

2. Anterior cingulate: a “collar” around the corpus callosum involved in decision making

3. Dopamine level is important for WM. A deficiency in dopamine can impair WM performance.

Long-Term Memory

Mem

Implicit Memory

Explicit Memory

Semantic Episodic Priming Procedural Learning

Classical Conditioning

LTM Processes

1. Encoding2. Consolidation3. Storage4. Retrieval

Consolidation

1. Memories become more stable and resistant to interference over time

2. Memories are forgotten because they are not consolidated

3. LT memories are initially and temporarily stored in the hippocampus and adjoining medial temporal lobe structures

4. Over time they are transferred to the cortex for more “permanent” storage

Consolidation Details

1. Neuroscience construct; not cognitive psych.2. Evidence from TBI, amnesia, & sleep studies

1. Ribot’s gradient3. Takes time: hours to several days4. Unconscious mostly5. Much of it occurs during sleep6. Especially important for semantic memory7. Reactivations improve consolidation

Sleep and Consolidation

1. During both types of sleep2. Hippocampus “replays” experiences/learning

1. “Organizes” information; Strengthens connections2. “Moves” information to cortical areas

3. Sleep also reduces interference4. Sleep accounts for 69% of next day

improvement in procedural tasks5. Immediate sleep: 81% recall; delayed: 66%

LTM and the Brain Lobes

1. Temporal lobes---encoding, retrieval, consolidation, temporary storage of long-term episodic memories, semantic storage

2. Frontal lobes---memory strategies for encoding and retrieval (no actual storage of long-term memories)

3. Parietal---auditory and spatial storage4. Occipital---visuospatial storage

The Hippocampus

Hippocampus Image

The Hippocampus

1. Horseshoe shape in temporal lobe2. Necessary for STM-LTM transfer3. Encodes, consolidates, retrieves,

reintegrates4. May hold some episodic permanently5. Explicit memory only6. Sensitive to injury, glucose, oxygen, &

cortisol levels

The Hippocampus

1. Responsible for transferring memories to cortex (consolidation); active during sleep

2. Has a spatial side and a verbal side3. Spatial memory depends on it (more than

verbal memory); London’s taxi drivers4. Large EEG signals5. High levels of glucocorticoid receptors6. Size matters; bigger is better

The Hippocampus

1. Clearly necessary for episodic memory2. May not be as essential for semantic memory3. More involved with automatic retrieval;

conscious retrieval may depend more on the prefrontal cortex

4. The hippocampus primarily stores associations between memories rather than the memories themselves; holds the key to the connections

The Hippocampus

1. Hippocampus contains stem cells2. Hippocampus can grow (London taxi drivers)3. New neurons can be created from stem cells;

up to six weeks to mature4. Rats given Prozac had a 70 percent increase

in hippocampi cells after three weeks5. Humans who recover from depression have

more hippocampal volume than those who are chronically depressed

What the Hippocampus Needs

1. Oxygen2. Glucose3. Sleep (no permanent damage from lack of)4. No cortisol5. No impact6. No electricitySee YouTube Video: “Hippocampus Damage”

Non-Hippocampal LTM Structures

1. Thalamus (sensory relay station)2. Amygdala (emotions strengthen memories)3. Ventral visual stream (RAN)4. Parahippocampal cortex (surrounds

hippocampus; memory encoding)5. Entorhinal cortex (interface between

hippocampus and neocortex) 6. Perirhinal cortex (visual recognition)

Thalamus

1. Relay station for sensory information2. Near the hippocampus3. Involved in procedural memory formation4. Damage can cause amnesia

Amygdala

1. Is next to the hippocampus2. Recognizes stimuli with strong emotional

content or survival value3. Involved in classical conditioning4. May be involved in processing cross-modal

associations5. Does not actually store memories

Implicit Memory

1. Does not appear to depend on the hippocampus

2. Not consciously accessible3. Demonstrated through performance, not

recall4. Precedes development of explicit memory5. Example of implicit memory without explicit

Priming (Type of Implicit Memory)

1. Performance or recall is enhanced by recent, prior exposure

2. A form of very specific cueing; might be considered a memory process

3. Thought to be more perceptual processing than an actual memory function

4. “Milk” example5. Conceptual priming, such as an advance

organizer, is more explicit memory

Implicit Memory Structures

1. Generally not in medial temporal lobe but parietal and occipital

2. Cerebellum---conditioning3. Striatum---procedural learning4. Also, temporal cortices, amygdala, basal

ganglia, and motor cortex5. Range of structures may serve a protective

function

HM: Classic Case of No Hippocampus

1. Hippocampus, parahippocampal gyrus, entorhinal cortex, and amygdala were surgically removed in 1957 at age 27 because of epilepsy

2. Anterograde amnesia but STM and WM fine; could modify some semantic knowledge, such as celebrities’ names, but no new episodic memory

3. Some retrograde amnesia: Most events 1-2 years prior to surgery forgotten but prior semantic memory was good

HM

1. Performed normally on intellectual tests2. Could learn new motor skills (implicit, procedural

memory) but could not remember that he had learned them

3. He could draw a map of the house he was living in (that he moved to after the surgery), maybe from locomotion recall

4. His case had strong influence on memory theories and brain mapping of memory

5. https://youtu.be/KkaXNvzE4pk

Organization of LTM Memories from Cognitive Perspective

1. Schemas1. Logical linking at the neurological level may

result from thinking about two things at the same time (associations) (“fire together; wire together”)

2. Scripts3. Memory traces4. Associations

Organization and Storage of Memories

1. The connections more important and better understood than the cellular changes

2. Memory traces (pathways): synapses1. New memories: new synapses or changes in strength

3. In networks of interconnected neurons, with associated items linked more closely

4. Memories end up being stored in same areas that sensed, perceived, and processed info

5. Different components of a memory stored separately; then reintegrated during retrieval

Summary: The Neurological Sequence of LT Memory

1. Encoding, automatic or effortful1. Associations with related networks2. Strengthening, building, altering synapses3. Changing neurons and building neural networks

2. Temporary storage in hippocampus and medial temporal lobe

3. Consolidation and “permanent” storage in the cortex4. Memories end up being stored in same areas that

sensed, perceived, processed5. Recall

1. Uncued or minimally cued retrieval2. Cued retrieval or recognition