Neuropsychology of Memory Types of memory problems a

Neuropsychology of Memory • Types of memory problems – a pure amnesia is relatively rare – memory problems commonly occur after a traumatic brain injury (TBI) äTBI results in brain damage of two sorts: älesions ätwisting and shearing of brain structures and damage from bony protuberances of brain, particularly of the temporal lobes

Neuropsychology of Memory • Memory problems following TBI – post-traumatic amnesia – retrograde amnesia – anterograde amnesia

Neuropsychology of Memory • Memory problems following TBI – post-traumatic amnesia äafter severe TBI, individuals typically lose consciousness äafter they begin to regain consciousness, there is often a gradual recovery during which patients have difficulty keeping tracking of and remembering ongoing events, though there may be islands of lucidity and memory

Neuropsychology of Memory • Memory problems following TBI – retrograde amnesia ärefers to difficulty remembering events that occurred prior to injury äthe duration of amnesia varies but can extend back for several years äduration of retrograde amnesia typically shrinks as time passes

Neuropsychology of Memory • retrograde amnesia – duration of retrograde amnesia typically shrinks as time passes äe. g. , Russell (1959) described case of TBI as a result of a motorcycle accident ä 1 week post accident patient had lost 11 years of memory extending back from injury ä 2 weeks post accident patient had lost 2 years of memory äabout 10 weeks post injury memories of the last two years gradually returned

Neuropsychology of Memory • Memory problems following TBI • retrograde amnesia – formal testing of amnesics using famous faces/famous events has shown that there appears to be recall and recognition for old faces/events

Neuropsychology of Memory • retrograde amnesia – Butters & Cermak (1986) reported a case study of an eminent scientist (born 1914) who had written his autobiography only two years prior to becoming amnesic – tested him by asking him questions all drawn from his autobiography

Neuropsychology of Memory

Neuropsychology of Memory • retrograde amnesia – the pattern of results in some individuals appear to depend upon the nature of the retrieval cue presented – Warrington and Mc. Carthy (1988) showed that an amnesic patient was impaired when shown faces of famous people and asked to recall them – however, performance was normal when tested using recognition procedures

Neuropsychology of Memory • Memory problems following TBI • retrograde amnesia – this pattern of results suggests that retrograde amnesia is a retrieval problem – the pattern of damage/recovery -- from most distant to most recent -- has been argued by some to reflect a failure of consolidation (Ribot’s Law)

Neuropsychology of Memory • retrograde amnesia (RA) – pattern of memory gradient varies across patients (See Moscovitch et al. 2006) – If lesion restricted to hippocampus, RA extends back a few years only – When lesion includes entire hippocampal formation or extends to adjacent regions, severe ungraded RA (ungraded means that memory loss is equivalent at all time periods since acquisition); some labs have reported graded retroactive amnesia (recent memories are poorer than more remote memories)

Neuropsychology of Memory • Memory problems following TBI – anterograde amnesia ärefers to problems of learning new facts äalthough sometimes amnesia is specific to learning of verbal material (following LHD) or visuo -spatial material (following RHD) amnesia usually affects learning of many types of new information

Neuropsychology of Memory • Amnesic syndrome – dense form of memory deficit (as assessed by standardized testing) – relatively spared performance in other domains

Neuropsychology of Memory • Causes of amnesia äKorsakoff’s syndrome: drinking too much, eating too little, resulting in a thiamine deficiency and brain damage ädamage to brain following viral infection (e. g. , viral encephalitis) älesion to critical brain regions -- e. g. , HM äanoxia following heart attack, suicide attempt, etc.

Neuropsychology of Memory • Korsakoff’s syndrome – History ä 1881, a neurologist Carl Wernicke described a syndrome involving ataxia, oculomotor problems (gaze palsies and nystagmus), peripheral neuropathy, and confusion. This condition came to be known as Wernicke's encephalopathy äKorsakoff identified several patients with confusion, confabulation, sensory loss (especially of the feet), and anterograde amnesia

Neuropsychology of Memory • Korsakoff’s syndrome – Terminology äAtaxia– problems of muscular coordination; e. g. , people ‘duck walk’, feet apart, stiff-legged ä oculomotor problems (gaze palsies and nystagmus); abnormal eye movements—palsy = paralysis; nystagmus = involuntary rapid eye movements ä peripheral neuropathy = functional disturbance of peripheral nervous system

Neuropsychology of Memory • Korsakoff’s syndrome – History ä 1901 Bonhoffer realized Korsakoff’s patients had passed through the Wernicke's encephalopathy stage ätoday syndrome is called alcoholic Korsakoff syndrome. There are seven primary defining features of this disease:

Neuropsychology of Memory • Defining features of alcoholic Korsakoff syndrome äa. a retrograde amnesia with a temporal gradient (i. e. , better preserved memories from the remote than from the more recent past) äb. anterograde amnesia, meaning a nearly complete inability to learn new information from the time of the disease onset onward.

Neuropsychology of Memory äc. confabulation, which is a tendency to "fill in the gaps" of one's memories with plausible madeup stories. äconfabulations are rare among chronic Korsakoff patients who've had the disease for more than 5 years. Patients in the chronic stage are more likely to say "I don't know" or remain silent when faced with memory failures rather than to invent stories.

Neuropsychology of Memory äd. generally preserved IQ, including a normal digit span. äe. personality changes, the most common of which is apathy, passivity and indifference äinability to formulate and follow through a series of plans äf. lack of insight into their condition.

Neuropsychology of Memory – Korsakoff’s syndrome äworst impairments are on episodic memory tests, including list learning of words, figures, or faces, paragraph recall. ärelatively preserved semantic memory, including normal verbal fluency, vocabulary, rules of syntax, and basic arithmetic operations äintact sensori-motor memory (mirror tracing, mirror reading, pursuit rotor) äintact performance on implicit memory tests

Neuropsychology of Memory – Neuropathology of Korsakoff’s syndrome ämost sources attribute the amnesia to combined lesions in two diencephalic structures: regions of the thalamus and the mammillary bodies of the hypothalamus

Neuropsychology of Memory – HM, Hippocampal man – prototype of amnesia attributable to hippocampal damage äbilateral mesial temporal lobe resection extending 8 cm. back from the temporal tips, including the uncus and amygdala, and destroying the anterior two-thirds of the hippocampus and hippocampal gyrus, for the treatment of intractable epilepsy in 1954. äsurgery led to a permanent, severe anterograde amnesia, limited retrograde amnesia, and normal intelligence.

Neuropsychology of Memory • HM, Hippocampal man • Perceptual, motor, and cognitive functioning – IQ above average; language function intact, speech fluency slightly impaired; spelling poor – Appreciation of puns and linguistic ambiguities – Difficulty with some spatial tasks (e. g. , could not use spatial floor plan to navigate through a novel building, but could reproduce a floor plan of family home)

Neuropsychology of Memory • HM, Hippocampal man • Memory – Almost no capacity for new learning regardless of materials (short stories, word lists, pictures, etc. ) – But there are certain tasks requiring memory that are intact in H. M. – Mirror drawing

Neuropsychology of Memory • Multiple memory systems perspective • HM also had a retrograde amnesia; that is, he forgets events that occurred prior to surgery • His retrograde amnesia is temporally graded: The closer the event to surgery the less likely he was able to recall it • This finding suggests that the medial temporal lobes are not always required to retrieve memories

Neuropsychology of Memory • Multiple memory systems perspective • In 1962 Milner and colleagues showed that HM improved on tasks requiring skilled movements • HM’s improvement was comparable to controls • Skill was called ‘mirror tracing’ because it requires participants to draw the outline of a star while looking at the reflection of his hand the star on the mirror • HM had no conscious recollection of having done this task in the past • This is now viewed as a form of non-declarative or implicit memory task

H. M. ’s skilled learning performance

Encoding and Retrieval from longterm memory (LTM) • Multiple memory systems perspective • Other forms of implicit memory include priming effects that were reported by Warrington & Weiskrantz (1968) • In this study amnesics shown list of words (e. g. , absent); at test participants were given word stem completion task (e. g. , abs_____), and instructed to complete with first word that comes to mind • Results showed that amnesics (and controls) were more likely to complete word stems with previously studied words

Neuropsychology of Memory • HM, Hippocampal man • Gollins partial picture task – Task involves recognition of fragmented line drawings of 20 objects – 5 cards for each object with each card showing more and more fragments of the completed drawings – Participants are shown the 20 most difficult cards, then the next-most-difficult cards etc.

Neuropsychology of Memory • HM, Hippocampal man • Gollins partial picture task – Task involves recognition of fragmented line drawings of 20 objects – 5 cards for each object with each card showing more and more fragments of the completed drawings as shown in Figure – Participants are shown the 20 most difficult cards, then the next-most-difficult cards etc.

Neuropsychology of Memory • HM, Hippocampal man • Gollins partial picture task (Warrington & Weiskrantz, 1968 Nature, 217, 972 -974 – HM and normal controls performed this task, and then after an hour of intervening activity performed the task again – Results shown in next figure show that H. M. and controls made fewer errors on immediate tests as figures became more complete and when tested after a 1 hour delay there was memory retention – Conclusion. Perceptual memory is intact in H. M. ; perceptual memory does not appear to be mediated by medial temporal structures

Neuropsychology of Memory • HM, Hippocampal man • Dot pattern study (Gabrieli, 1990, Neuropsychologia, 28, 417 -427) – H. M. and controls were shown a series of 5 dots arranged in a unique pattern – Baseline draw. Participants (Ps) were instructed to draw any pattern they wanted (to control for pre-existing biases) – Experiment. Ps were shown a target pattern & copied that pattern on dots – After 6 hour delay, Ps were shown dots and were instructed to draw on dots any pattern they wanted

Neuropsychology of Memory • HM, Hippocampal man • Dot pattern study (Gabrieli, 1990, Neuropsychologia, 28, 417 -427) – H. M. and controls were shown a series of 5 dots arranged in a unique pattern – Baseline draw. Participants (Ps) were instructed to draw any pattern they wanted (to control for pre-existing biases) – Experiment. Ps were shown a target pattern & copied that pattern on dots – After 6 hour delay, Ps were shown dots and were instructed to draw on dots any pattern they wanted

Neuropsychology of Memory • HM, Hippocampal man • Dot pattern study (Gabrieli, 1990, Neuropsychologia, 28, 417 -427) – Implicit memory – percentage of target figures drawn that were identical to the copied target pattern (dots drawn in the baseline condition were not scored) – Explicit memory – Recognition memory – Ps were shown 4 dot patterns that drawn on the dots and selected the dot pattern that had been copied

Dot pattern • Top figure shows dot pattern and target stimuli • Left panel of bottom figure shows explicit performance and right panel shows implicit performance of H. M. and Controls

Neuropsychology of Memory • HM, Hippocampal man • Dot pattern study (Gabrieli, 1990, Neuropsychologia, 28, 417 -427) – Implicit memory – dot pattern priming equivalent for H. M. and controls – Explicit memory – H. M. impaired on recognition memory test compared to controls

Neuropsychology of Memory • HM, Hippocampal man • Dot pattern study (Gabrieli, 1990, Neuropsychologia, 28, 417 -427) – Gabrieli and colleagues argued that this finding cannot be attributable to activation of a preexisting memory (e. g. , a semantic representation) – Proposed that it is attributable to a type of perceptual priming, perhaps of a non-semantic structural description of a pattern

Artificial grammar learning • Amnesics can have intact capacity for learning certain cognitive skills • E. g. , artificial grammar such as shown in Figure • Participants were shown novel letter strings one at a time and were asked to classify the strings as grammatical or nongrammatical

Artificial grammar learning • Participants were then tested to determine whether they could distinguish between grammatical and nongrammatical letter strings • Results showed that amnesics and normal controls could classify correctly about twothirds of the letter strings •

Artificial Grammar • Top panel shows an example of an artificial grammar • Bottom panel shows examples of grammatical and nongrammatical strings • Knowlton et al. (1992). Psychological Science, 3, 172 -179

Artificial grammar learning • Conclusions – Declarative memory and MTL not required to encode in memory those processes associated with the encoding into memory artificial grammars

Recognition memory: dualprocess models • Several lines of evidence support the idea that two distinct processes (recollection, familiarity) mediated by different brain regions underlie recognition memory – Example. See face of a person – you recognize the person as familiar but are unable to recollect anything about the person, when or where you met that person – Recollection – you recognize that person and can recollect details about that person –

Recognition memory: dualprocess models • Evidence for dual process models (behavioral) – Speeded recognition tests have shown that item recognition tests (was this item studied) are made more quickly than associative recognition tests (when or where was this item studied) – Analysis of confidence intervals has shown that when hit rate is plotted against false alarm rate, curves are different for associative recognition (linear) versus item recognition (curvilinear) – also two different parameters are required to account for shape of curve suggesting that two distinctly different cognitive processes are operating

Recognition memory: dualprocess models • Evidence for dual process models (behavioral) – Yonelinas has proposed that familiarity reflects the strength of the memory trace (an is quantitative) – Recollection reflects retrieval of qualitative, contextual information

Recognition memory: dualprocess models • Evidence for dual process models (lesion) – Amnesics are much more impaired on associative recognition tests than on item recognition tests – Analysis of confidence intervals has shown that only 1 type of process (curvilinear) is required to account for recognition performance – See Yonelinas (2002) for further details

Neuropsychology of Memory • Functional characteristics of amnesia – working memory is intact – semantic memory is spared (controversial) – episodic memory is impaired – procedural memory is intact

Neuropsychology of Memory • Theoretical implications of amnesia – provides evidence for STM versus LTM distinction – supports the notion that there are different systems mediating explicit (episodic) and implicit (procedural memory) – may indicate that semantic and episodic memory can be fractionated – may provide insight into nature of consciousness

Neuropsychology of Memory • Memory and Consciousness – Tulving has proposed that different memory systems have associated with them different levels of consciousness änoetic -- awareness äepisodic memory -- autonoetic, self awareness äsemantic memory -- noetic, aware of the information, but not aware of event äprocedural memory -- anoetic no conscious awareness

Neuropsychology of Memory Episodic Autonoetic Semantic Noetic Procedural Anoetic

Neuropsychology of Declarative Memory Brain regions mediating declarative memory – what is common appears to be the circuit linking regions in the temporal lobes, the hippocampus, the mammiliary bodies and regions of the thalamus (note: review Korsakoff’s) – Next slides will review this in more detail – See Eichenbaum (2002). The cognitive neuroscience of memory and Moscovitch et al. (2005). 207, 35 -66. Journal of Anatomy

Neuropsychology of Declarative Memory • Medial temporal lobe structures viewed from the side (saggital section) • Moscovitch et al. (2005)

Recollective and familiarity memory systems

Neuropsychology of Declarative Memory Brain regions mediating declarative memory – 3 major component brain regions involved in declarative memory – Cerebral cortex, parahippocampal region – Hippocampus – Parahippocampal region consists of perirhinal cortex, parahippocampal cortex, and entorhinal cortex

Neuropsychology of Declarative Memory Brain regions mediating declarative memory: flow of information – Bidirectional connections between cortex and parahippocampal region – Bidirectional connections between parahippocampal region and hippocampus – Highly processed information comes from association areas of the cortex – Info further processed by the parahippocampal region and hippocampus before being projected back to regions that provided the information

Neuropsychology of Declarative Memory Brain regions mediating declarative memory: flow of information – Aside: Background info about how sensory and motor processing makes its way to association areas – Sensory info ->primary cortical areas (e. g. , visual cortex) -> secondary and tertiary unimodal sensory regions -> multimodal association areas located in temporal, parietal, and frontal lobes as well as in cingulate area

Neuropsychology of Declarative Memory Brain regions mediating declarative memory: flow of information – Aside: Background info about how sensory and motor processing makes its way to association areas – Motor ->primary cortical area (e. g. , motor cortex) ultimately projects to prefrontal and cingulate areas

Neuropsychology of Declarative Memory Brain regions mediating declarative memory: flow of information – Association areas of the temporal -- object identification using info from multiple sensory modalities – Association areas parietal lobes – process spatial info about visual and other sensory inputs – Prefrontal and cingulate areas – process info about the significance of stimuli, rules of tasks, and plans for tasks – Each of these association areas provides input to the parahippocampal region

Neuropsychology of Declarative Memory Parahippocampal region – Consists of 3 distinct areas ä Perirhinal cortex ä Parahippocampal cortex ä Entorhinal cortex – Inputs to parahippocampal region come from virtually every higher-order association area – Perirhinal and parahippocampal cortices project to the parts of the entorhinal cortex

Neuropsychology of Declarative Memory Parahippocampal region – Anterior cortical inputs from prefrontal cortex and anterior cingulate project to the perirhinal cortex and entorhinal cortex – Posterior cortical inputs (temporal and parietal regions) project to the perirhinal and parahippocampal cortices

Neuropsychology of Declarative Memory Hippocampus – Consists of several subfields including the äCA 1, CA 3 äDentate gyrus äSubiculum – Connected bidirectionally to the fornix, the prefrontal cortex and the parahippocampal region – Also connected to regions of the thalamus (anterior)

Neuropsychology of Declarative Memory Linking brain and memory – Distinct memory systems reviewed in this lecture include – Recollective memory – conscious recollection of experiences (autonoetic) – Familiarity memory – memory for stimuli rather than for events; stimuli are recognized as familiar wthout being placed in spatial/temporal context (noetic) – Semantic memory – memory for noncontextual content of experience or knowledge about the world (facts, concepts, word meanings, objects, tools etc. ) – It includes knowledge about ourselves (DOB, where we lived, our jobs, facts about family etc.

Neuropsychology of Declarative Memory Linking brain and memory – Recollective memory äRelies on hippocampus, mamiliary bodies, and anterior thalamic nuclei via the fornix (see solid lines in Figure) – Familiarity memory äRelies on circuit involving perirhinal cortex and medial dorsal thalamus äDamage to this circuit will impair recognition of even single items (see dotted lines in Figure) – Parahippocampal cortex may mediate place memory

Recollective and familiarity memory systems

Neuropsychology of Declarative Memory Linking brain and memory – Semantic memory äDoes not depend on medial temporal lobe and diencephalic structures äSemantic memory relies on a network of anterior and posterior neocortical structures äPrecise structures depend upon attributes of memory (see next slide—different colors represent site of different memory attributes – (e. g. , form, motion) äBrain regions include lateral and anterior temporal lobe regions and the lateral inferior prefrontal cortex particularly in the left hemisphere (see next slide)

Martin & Chao (2001). Current Opinion in Neurobiology (a) Ventral brain regions from occipital to temporal lobes—represent color and shape properties (fusiform gyrus) (b) Left lateral areas– motor areas in prefrontal cortex and parietal areas represent manipulation of objects; posterior temporal lobes represent motion properties of objects

Semantic Memory