Biology subjects

Sommer, V. R.

Publications and source records attributed to Sommer, V. R..

4 recordsLinked to original sources

bioRxiv2021

Age-related declines in neural selectivity manifest differentially during encoding and recognition

The authors have withdrawn the preprint due to two errors in the analyses: The first error was a failure to account for three dummy volumes (TR = 2s) collected at the beginning of each experimental run. The second error was a coding error related to the definition of the category-selective clusters. Since correcting for these errors drastically altered the results and conclusions of this paper, the authors have withdrawn the preprint and retracted the published paper (https://doi.org/10.1016/j.neurobiolaging.2021.12.001). A report comparing original and corrected results can be found on https://osf.io/7n3mz/. If you have any questions please contact the corresponding author (sander@mpib-berlin.mpg.de).

neuroscience↗

bioRxiv2020

Memory specificity is linked to repetition effects in event-related potentials across the lifespan

The specificity with which past experiences can be remembered varies across the lifespan, possibly due to differences in how precisely information is encoded. Memory formation can be investigated through repetition effects, the common finding that neural activity is altered when stimuli are repeated. However, whether differences in this indirect measure of memory formation relate to lifespan differences in memory specificity has not yet been established. In the present study, we examined repetition effects in event-related potentials and their relation to recognition. During incidental encoding, children (aged 7-9 years), young adults (18-30 years), and older adults (65-76 years) viewed repeated object images from different categories. During subsequent recognition, we distinguished memory for the specific items versus the general categories. We identified repetition suppression in all age groups, and repetition enhancement for adults. Furthermore, individual item recognition performance comprising lure discrimination was positively associated with the magnitude of the neural repetition effects, which did not differ between groups, indicating common neural mechanisms of memory formation. Our findings demonstrate that neural repetition effects reflect the formation of highly specific memory representations and highlight their significance as a neural indicator of individual differences in episodic memory encoding across the lifespan.

neuroscience↗

bioRxiv2020

Tracking age differences in neural distinctiveness across representational levels

The authors have withdrawn the preprint due to two errors in the analyses: The first error was a failure to account for three dummy volumes (TR = 2s) collected at the beginning of each experimental run. The second error was a coding error related to the definition of the category-selective clusters. Since correcting for these errors drastically altered the results and conclusions of this paper, the authors have withdrawn the preprint and retracted the published paper. More information as well as a report comparing original and corrected results can be found on https://osf.io/t8dpv/. If you have any questions please contact the corresponding author (sander@mpib-berlin.mpg.de).

neuroscience↗

bioRxiv2019

Neural pattern similarity differentially affects memory performance of younger and older adults

Age-related memory decline is associated with changes in neural functioning but little is known about how aging affects the quality of information representation in the brain. Whereas a long-standing hypothesis of the aging literature links cognitive impairments to less distinct neural representations in old age, memory studies have shown that high similarity between activity patterns benefits memory performance for the respective stimuli. Here, we addressed this apparent conflict by investigating between-item representational similarity in 50 younger (19-27 years old) and 63 older (63-75 years old) human adults (male and female) who studied scene-word associations using a mnemonic imagery strategy while electroencephalography was recorded. We compared the similarity of spatiotemporal frequency patterns elicited during encoding of items with different subsequent memory fate. Compared to younger adults, older adults memory representations were more similar to each other but items that elicited the most similar activity patterns early in the encoding trial were those that were best remembered by older adults. In contrast, young adults memory performance benefited from decreased similarity between earlier and later periods in the encoding trials, which might reflect their better success in forming unique memorable mental images of the joint picture-word pair. Our results advance the understanding of the representational properties that give rise to memory quality as well as how these properties change in the course of aging. Significance statementDeclining memory abilities are one of the most evident limitations for humans when growing older. Despite recent advances of our understanding of how the brain represents and stores information in distributed activation patterns, little is known about how the quality of information representation changes during aging and thus affects memory performance. We investigated how the similarity between neural representations relates to subsequent memory quality in younger and older adults. We present novel evidence that the interaction of pattern similarity and memory performance differs between age groups: Older adults benefited from increased similarity during early encoding whereas young adults benefited from decreased similarity between early and later encoding. These results provide insights into the nature of memory and age-related memory deficits.

neuroscience↗