Correlating MRI-Based Brain Volumetry and Cognitive Assessment in Down Syndrome Patients

INTRODUCTIONDown syndrome (DS) is the most common genetic cause of intellectual disability. Children and adults with DS show deficits in various aspects of language performance and explicit memory. Here we use magnetic resonance imaging (MRI) on children and adults with DS to characterize changes in the volume of specific brain structures involved in memory and language and their relationship to features of cognitive-behavioral phenotypes.METHODSThirteen children and adults with the DS phenotype and 12 age- and gender-matched healthy controls were analyzed by MRI and underwent a psychological evaluation for language and cognitive abilities.RESULTSThe neuropsychological profile of DS patients showed deficits in different cognition and language domains in correlation with reduced volumes of specific regional and subregional brain structures. Intriguingly, our DS patients showed also a reduced parahippocampal gyrus volume, in contrast with the results found by other researchers.CONCLUSIONSThe memory functions and language skills affected in our DS patients correlate significantly with the reduced volume of specific brain regions, allowing us to understand DS's cognitive-behavioral phenotype. Our results provide an essential basis for early intervention and the design of rehabilitation management protocols.

Judgments of Learning Reveal Conscious Access to Stimulus Memorability

Despite the massive capacity of visual long-term memory, individuals do not successfully encode all visual information they wish to remember. This variability in encoding success has been traditionally ascribed to fluctuations in individuals’ cognitive states (e.g., sustained attention) and differences in memory encoding processes (e.g., depth of encoding). However, recent work has shown that a considerable amount of variability in encoding success stems from intrinsic stimulus properties that determine the ease of encoding across individuals. While researchers have identified several perceptual and semantic properties that contribute to this stimulus memorability phenomenon, much remains unknown, including whether individuals are aware of the memorability of stimuli they encounter. In the present study, we investigated whether individuals have conscious access to the memorability of real-world stimuli while forming self-referential judgments of learning (JOL) during explicit memory encoding (Experiments 1A-B) and when asked about the perceived memorability of a stimulus in the absence of attempted encoding (Experiments 2A-B). We found that both JOLs and perceived memorability estimates were consistent across individuals and reliably predicted stimulus memorability. However, this apparent access to the properties that define memorability was not comprehensive. Individuals unexpectedly remembered and forgot consistent sets of stimuli as well. Thus, our findings demonstrate that individuals have conscious access to some—but not all—aspects of stimulus memorability and that this access exists regardless of the present demands on stimulus encoding.

Do naps benefit novel word learning? Developmental differences and white matter correlates

Behavioural and neuroimaging data suggest that memory representations of newly learned words undergo changes during nocturnal sleep, including improvements in explicit recall and lexical integration (i.e., after sleep, novel words compete with existing words during online word recognition). Some studies have revealed larger sleep-benefits in children relative to adults. However, whether daytime naps play a similar facilitatory role is unclear. We investigated the effect of a daytime nap (relative to wake) on explicit memory (recall/recognition) and lexical integration (lexical competition) of newly learned novel words in young adults and children aged 10-12 years, also exploring white matter correlates of the pre- and post-nap effects of word learning in the child group with diffusion weighted MRI. In both age groups, a nap maintained explicit memory of novel words and wake led to forgetting. However, there was an age group interaction when comparing change in recall over the nap: children showed a slight improvement whereas adults showed a slight decline. There was no evidence of lexical integration at any point. Although children spent proportionally more time in slow-wave sleep (SWS) than adults, neither SWS nor spindle parameters correlated with over-nap changes in word learning. For children, increased fractional anisotropy (FA) in the uncinate fasciculus and arcuate fasciculus were associated with the recognition of novel words immediately after learning, and FA in the right arcuate fasciculus was further associated with changes in recall of novel words over a nap, supporting the importance of these tracts in the word learning and consolidation process. These findings point to a protective role of naps in word learning, and emphasize the need to advance theories of word learning by better understanding both the active and passive roles that sleep plays in supporting vocabulary consolidation over development.

Finding the Drastic: Exploring Forms of Attention in Piano Performance

<p>While Carolyn Abbate’s essay “Music – Drastic or Gnostic” sets provocative parameters for considering performance, she also makes a bold stand on the mutual exclusivity of the knowing or gnostic mind and active or drastic body in performance. Abbate suggests that when one is involved in the real-time experience of music (i.e. performance) there is no room for thought because conceptual awareness interrupts the real-time experience. Thus, drastic precludes gnostic. Yet many performers speak about the need to negotiate a balance between mind and body in performance. This implies that an imbalance can occur in either direction, that over-thinking the execution is not conducive to flow but that the ultimate experience of the music ‘playing itself’ may also incur an undesirable sense of not being in conscious control. This paper aims to explore the limits of a gnostic approach and the parameters for a drastic performance. My own experience has demonstrated the ways in which too much conscious control - or rather, too much conscious attention on certain tactile aspects of playing - can end up hampering the physical execution. Indeed, Science Daily has summarised recent research in the Journal of Neuroscience that confirms scientifically that over-thinking can be detrimental to performance. Implicit memory (unconscious and expressed by means other than words) and explicit memory (which is conscious and can be described in words) each operate from different parts of the brain; and the implication is that physical performance in most cases requires the deployment of implicit as well as explicit memory. For a pianist, in other words, on the one hand the ‘action’ must become instinctive at some point because one’s attention cannot focus simultaneously on the fingers prior to every sound and on the sound itself. On the other hand, it is also not desirable simply to deliver the action to some level of drastic, or pure ‘doing’ (as the ancient meaning of the word suggests), even to a meta-drastic point where the music ‘plays itself’. Thus it would seem that Abate’s stipulation gnostic or drastic requires further reflection. Through my critical analysis of this discussion, I would like finally to be able to redress the balance between a gnostic and drastic approach in my own performance. Resituating the mind-body balance itself requires a shift in consciousness: a shift that effectively distracts me from overt tactile awareness and places my foreground attention to sound. This shift, ironically, requires an immense conscious effort: in other words, my shift towards the drastic is launched by the gnostic. Through documenting the process of my own journey from gnostic/explicit performance to drastic/implicit performance, I will propose that a specific balanced blend is ideal: that is, I need to move from a cognitive or conscious process that focuses on physical aspects of performance, in order to bring an unfettered consciousness of sound to the foreground attention. If I can suppress my conscious attention to the kinetics of playing the piano and this very suppression permits a focus on sound itself, will that be a shutting down of one kind of excessive cognitive effort and signal a release of the drastic, or simply resituate the gnostic? For myself, finding my way to trusting a drastic approach and yet balance it with a gnostic input is imperative if I am to find music making a pleasure.</p>

Finding the Drastic: Exploring Forms of Attention in Piano Performance

<p>While Carolyn Abbate’s essay “Music – Drastic or Gnostic” sets provocative parameters for considering performance, she also makes a bold stand on the mutual exclusivity of the knowing or gnostic mind and active or drastic body in performance. Abbate suggests that when one is involved in the real-time experience of music (i.e. performance) there is no room for thought because conceptual awareness interrupts the real-time experience. Thus, drastic precludes gnostic. Yet many performers speak about the need to negotiate a balance between mind and body in performance. This implies that an imbalance can occur in either direction, that over-thinking the execution is not conducive to flow but that the ultimate experience of the music ‘playing itself’ may also incur an undesirable sense of not being in conscious control. This paper aims to explore the limits of a gnostic approach and the parameters for a drastic performance. My own experience has demonstrated the ways in which too much conscious control - or rather, too much conscious attention on certain tactile aspects of playing - can end up hampering the physical execution. Indeed, Science Daily has summarised recent research in the Journal of Neuroscience that confirms scientifically that over-thinking can be detrimental to performance. Implicit memory (unconscious and expressed by means other than words) and explicit memory (which is conscious and can be described in words) each operate from different parts of the brain; and the implication is that physical performance in most cases requires the deployment of implicit as well as explicit memory. For a pianist, in other words, on the one hand the ‘action’ must become instinctive at some point because one’s attention cannot focus simultaneously on the fingers prior to every sound and on the sound itself. On the other hand, it is also not desirable simply to deliver the action to some level of drastic, or pure ‘doing’ (as the ancient meaning of the word suggests), even to a meta-drastic point where the music ‘plays itself’. Thus it would seem that Abate’s stipulation gnostic or drastic requires further reflection. Through my critical analysis of this discussion, I would like finally to be able to redress the balance between a gnostic and drastic approach in my own performance. Resituating the mind-body balance itself requires a shift in consciousness: a shift that effectively distracts me from overt tactile awareness and places my foreground attention to sound. This shift, ironically, requires an immense conscious effort: in other words, my shift towards the drastic is launched by the gnostic. Through documenting the process of my own journey from gnostic/explicit performance to drastic/implicit performance, I will propose that a specific balanced blend is ideal: that is, I need to move from a cognitive or conscious process that focuses on physical aspects of performance, in order to bring an unfettered consciousness of sound to the foreground attention. If I can suppress my conscious attention to the kinetics of playing the piano and this very suppression permits a focus on sound itself, will that be a shutting down of one kind of excessive cognitive effort and signal a release of the drastic, or simply resituate the gnostic? For myself, finding my way to trusting a drastic approach and yet balance it with a gnostic input is imperative if I am to find music making a pleasure.</p>

Implicit and Explicit Memory in Depression/ Dysphoria: an Analysis of the Contribution of Perceptual and Conceptual Processes

<p>Earlier studies have shown impaired explicit test and normal implicit test performance in participants classified as depressed. A number of different models have been put forward to explain this 'typical' test dissociation including the memory systems, processing, and activation - elaboration models. Blaxton (1989, 1992) has pointed out that to date most test designs have confounded the memory systems and processing models. The aim of this series of experiments was to systematically compare the effects of depression on the processing and memory systems models and in so doing provide a more precise explanation for the effects of depression on human memory. Across Experiments 1 - 4 the performance of participants with depression or dysphoria were examined on implicit and explicit memory tests which were designed to tap either predominantly perceptual or conceptual processes. In Experiment 1 the conceptual tests of category association (implicit) and semantic cued recall (explicit) were compared with the perceptual tests of word fragment completion (implicit) and graphemic cued recall (explicit). In Experiment 2 the perceptual tests of perceptual identification (implicit) and the 'mixed' test of anagram solution (implicit) were compared with the conceptual free recall test (explicit). Both experiments used dysphoric university students and found no effects of dysphoria in comparison to normal controls matched for age, sex and education levels. Experiment 3 compared the conceptual category association (implicit) and free recall (explicit) tests with the perceptual word fragment completion test (implicit) using participants diagnosed with major depression disorder. This revealed significant impairments in both the conceptual tests while the perceptual test was intact. Experiment 4 compared the implicit word association test with the explicit word association test using dysphoric university students. Experiment 4 found that dysphoric participants were impaired in performing the explicit test while the implicit test remained intact. These findings suggest that dysphoria has no effect on implicit tests, but can effect conceptual explicit test measures. Clinical depression effects both conceptual implicit and conceptual explicit test measures. While these results support aspects of both the memory systems and processing models these findings may be best accommodated by a model which combines these models. The revised memory systems model is discussed as one means of achieving this.</p>

Implicit and Explicit Memory in Depression/ Dysphoria: an Analysis of the Contribution of Perceptual and Conceptual Processes

<p>Earlier studies have shown impaired explicit test and normal implicit test performance in participants classified as depressed. A number of different models have been put forward to explain this 'typical' test dissociation including the memory systems, processing, and activation - elaboration models. Blaxton (1989, 1992) has pointed out that to date most test designs have confounded the memory systems and processing models. The aim of this series of experiments was to systematically compare the effects of depression on the processing and memory systems models and in so doing provide a more precise explanation for the effects of depression on human memory. Across Experiments 1 - 4 the performance of participants with depression or dysphoria were examined on implicit and explicit memory tests which were designed to tap either predominantly perceptual or conceptual processes. In Experiment 1 the conceptual tests of category association (implicit) and semantic cued recall (explicit) were compared with the perceptual tests of word fragment completion (implicit) and graphemic cued recall (explicit). In Experiment 2 the perceptual tests of perceptual identification (implicit) and the 'mixed' test of anagram solution (implicit) were compared with the conceptual free recall test (explicit). Both experiments used dysphoric university students and found no effects of dysphoria in comparison to normal controls matched for age, sex and education levels. Experiment 3 compared the conceptual category association (implicit) and free recall (explicit) tests with the perceptual word fragment completion test (implicit) using participants diagnosed with major depression disorder. This revealed significant impairments in both the conceptual tests while the perceptual test was intact. Experiment 4 compared the implicit word association test with the explicit word association test using dysphoric university students. Experiment 4 found that dysphoric participants were impaired in performing the explicit test while the implicit test remained intact. These findings suggest that dysphoria has no effect on implicit tests, but can effect conceptual explicit test measures. Clinical depression effects both conceptual implicit and conceptual explicit test measures. While these results support aspects of both the memory systems and processing models these findings may be best accommodated by a model which combines these models. The revised memory systems model is discussed as one means of achieving this.</p>

Limbic System

Unlike the lobes of the cortex, which are regionally defined, the limbic “lobe” includes highly interconnected circuits that span cortical, subcortical, and brainstem components. The major functions of the limbic system include mediating emotional and behavioral responses, memory, and learning. From a functional standpoint, the limbic system can be conceptualized as including an anterior circuit, centered in the amygdala and primarily involved in emotion and behavioral drive, and a posterior circuit, centered in the hippocampus and crucial for encoding and retrieving declarative (explicit) memory.

Implicit and Explicit Memory in Youths with High-Functioning Autism Spectrum Disorder: A Case-Control Study

Individuals with autism spectrum disorder (ASD) usually manifest heterogeneous impairments in their higher cognitive functions, including their implicit memory (IM) and explicit memory (EM). However, the findings on IM and EM in youths with ASD remain debated. The aim of this study was to clarify such conflicting results by examining IM and EM using two comparable versions of the Serial Reaction Time Task (SRTT) in the same group of children and adolescents with ASD. Twenty-five youths with high-functioning ASD and 29 age-matched and IQ-matched typically developing youths undertook both tasks. The ability to implicitly learn the temporal sequence of events across the blocks in the SRTT was intact in the youths with ASD. When they were tested for EM, the participants with ASD did not experience a significant reduction in their reaction times during the blocks with the previously learned sequence, suggesting an impairment in EM. Moreover, the participants with ASD were less accurate and made more omissions than the controls in the EM task. The implications of these findings for the establishment of tailored educational programs for children with high-functioning ASD are discussed.