A comparison of visual working memory and episodic memory performance in younger and older adults

Item does not contain fulltextWorking memory and episodic memory decline with age.  However, as they are typically studied separately, it is largely unknown whether age-associated differences are similar. A task design was developed in which visual working memory and episodic memory performances were measured using the same stimuli, with both tasks involving context binding. A 2-back working memory task was followed by a surprise subsequent recognition memory task that assessed incidental encoding of object locations of the 2-back task. The study compared performance of younger (N=30; Mage=23.5, SDage=2.9, range=20-29) and older adults (N=29; Mage=72.1, SDage=6.8, range=62-90). Older adults performed worse than younger adults, without an interaction effect. In younger, but not in older adults, performance on the two tasks was related. We conclude that although age differences (Young>Older) are similar in the working memory and incidental associative memory tasks, the relationship between the two memory systems differs as a function of age group.20 p

Are visual working memory and episodic memory distinct processes? Insight from stroke patients by lesion-symptom mapping

Working memory and episodic memory are two different processes, although the nature of their interrelationship is debated. As these processes are predominantly studied in isolation, it is unclear whether they crucially rely on different neural substrates. To obtain more insight in this, 81 adults with sub-acute ischemic stroke and 29 elderly controls were assessed on a visual working memory task, followed by a surprise subsequent memory test for the same stimuli. Multivariate, atlas- and track-based lesion-symptom mapping (LSM) analyses were performed to identify anatomical correlates of visual memory. Behavioral results gave moderate evidence for independence between discriminability in working memory and subsequent memory, and strong evidence for a correlation in response bias on the two tasks in stroke patients. LSM analyses suggested there might be independent regions associated with working memory and episodic memory. Lesions in the right arcuate fasciculus were more strongly associated with discriminability in working memory than in subsequent memory, while lesions in the frontal operculum in the right hemisphere were more strongly associated with criterion setting in subsequent memory. These findings support the view that some processes involved in working memory and episodic memory rely on separate mechanisms, while acknowledging that there might also be shared processes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00429-021-02281-0

Mid-range visual deficits after stroke:Prevalence and co-occurrence

Visual deficits are common after stroke and are powerful predictors for the chronic functional outcome. However, while basic visual field and recognition deficits are relatively easy to assess with standardized methods, selective deficits in visual primitives, such as shape or motion, are harder to identify, as they often require a symmetrical bilateral posterior lesion in order to provoke full field deficits. Therefore, we do not know how often they occur. Nevertheless, they can have severe repercussions for daily-life functioning. We aimed to investigate the prevalence and co-occurrence of hemifield “mid-range” visual deficits (i.e. color, shape, location, orientation, correlated motion, contrast, texture and glossiness), using a novel experimental set-up with a gaze-contingent presentation of the stimuli. To this end, a prospective cohort of 220 ischemic (sub)cortical stroke patients and a healthy control group was assessed with this set-up. When comparing performance of patients with controls, the results showed that deficits in motion-perception were most prevalent (26%), followed by color (22%), texture (22%), location (21%), orientation (18%), contrast (14%), shape (14%) and glossiness (13%). 63% of the stroke patients showed one or more mid-range visual deficits. Overlap of deficits was small; they mostly occurred in isolation or co-occurred with only one or two other deficits. To conclude, it was found that deficits in “mid-range” visual functions were very prevalent. These deficits are likely to affect the chronic post-stroke condition. Since we found no strong patterns of co-occurrences, we suggest that an assessment of deficits at this level of visual processing requires screening the full range of visual functions

Neurocognitive mechanisms of visual working memory and episodic memory in healthy aging and after stroke

Item does not contain fulltextOur surroundings consist of scenes and objects that have a multitude of visual features: shape, color, texture, size, orientation, and location. We are able to remember which object was where and what features belong to it by forming an internal representation of features and their conjunctions. Some representations only last for a brief period, they are kept in working memory, while other representations remain over a longer period of time, known as episodic memory. The aim of this thesis was to investigate how memory subsystems relate at a behavioral and neural level using novel behavioral paradigms, lesion-symptom mapping, and computational modeling, in healthy adults and stroke patients. Lesions studies in this thesis support the notion of a widely distributed frontoparietal network underlying memory, with a suggestion of specialization for memory subsystems (working memory and episodic memory; feature reporting and binding) and multiple visual representations in the brain. Representations in different areas might compensate for impaired encoding in lesioned areas explaining mostly subtle visual memory impairments following stroke. Experimental studies in this thesis showed that, at a group level, controls outperform patients and younger adults perform better than older adults. At the same time, selective deficits in different subsystems of visual memory are prevalent. This indicates that different neural mechanisms may be involved. It also stresses the need for broad memory examination, as selective memory deficits might easily be missed in standard clinical assessment where testing mainly with verbal materials and with a maximum delay of 30 minutes is the standard.University of Amsterdam, 25 september 2020Promotores : Haan, E.H.F. de, Kessels, R.P.C., Leeuw, H.F. de Co-promotor : Geerligs, L.215 p

Neurocognitive mechanisms of visual working memory and episodic memory in healthy aging and after stroke

Our surroundings consist of scenes and objects that have a multitude of visual features: shape, color, texture, size, orientation, and location. We are able to remember which object was where and what features belong to it by forming an internal representation of features and their conjunctions. Some representations only last for a brief period, they are kept in working memory, while other representations remain over a longer period of time, known as episodic memory. The aim of this thesis was to investigate how memory subsystems relate at a behavioral and neural level using novel behavioral paradigms, lesion-symptom mapping, and computational modeling, in healthy adults and stroke patients. Lesions studies in this thesis support the notion of a widely distributed frontoparietal network underlying memory, with a suggestion of specialization for memory subsystems (working memory and episodic memory; feature reporting and binding) and multiple visual representations in the brain. Representations in different areas might compensate for impaired encoding in lesioned areas explaining mostly subtle visual memory impairments following stroke. Experimental studies in this thesis showed that, at a group level, controls outperform patients and younger adults perform better than older adults. At the same time, selective deficits in different subsystems of visual memory are prevalent. This indicates that different neural mechanisms may be involved. It also stresses the need for broad memory examination, as selective memory deficits might easily be missed in standard clinical assessment where testing mainly with verbal materials and with a maximum delay of 30 minutes is the standard