| 31. |
- Nordin, Kristin
(författare)
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Aging Along the Hippocampal Axis : Structure, Function and Whole-brain Connections in Association with Memory
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hippocampus-dependent functions display marked reductions in older age, an observation that has led to the extensive study of age effects on hippocampal properties. Even though research indicates that the hippocampus is structurally and functionally heterogeneous along its longitudinal axis, its anterior and posterior regions differentially supporting episodic and spatial memory representations, few studies explicitly consider age effects in relation to axis. Relatedly, as men and women commonly differ in episodic and spatial memory performance, and sometimes also in rates of age-related hippocampal atrophy, sex could be a potential modifier of age effects. The aim of this thesis was therefore to assess age effects on the hippocampus and its role in episodic and spatial memory across young (20-35 years), middle-aged (40-50 years) and older (60-70 years) adults, adopting a longitudinal-axis approach while considering interactions with sex. Study I evaluated hippocampal volume and activation in relation to associative memory across middle-aged and older adults. Age differences in associative memory were largest in men and paralleled by smaller volumes and less activation in the anterior hippocampus. Study II assessed hippocampus-dependent network-like organization of gray matter by measures of structural whole-brain covariance. The anterior and posterior hippocampus showed shared and distinct patterns of covariance, which were qualitatively comparable across age groups. However, participants’ expression of these patterns decreased as a function of age, comparably for men and women, and showed significant associations with episodic memory. Study III investigated age effects on resting-state functional connectivity and demonstrated that both the anterior and posterior hippocampus decreased in connectivity with several brain regions across middle-aged and older adults. Memory was only associated with age-related connectivity of the posterior hippocampus: episodic memory negatively with connectivity increasing as a function of age, and spatial memory positively with connectivity that decreased. These studies demonstrate distinct effects of age on the anterior and posterior hippocampus, and show that age-related decline of these regions differentially relates to episodic and spatial memory. Overall, findings highlight the importance of explicitly considering the heterogeneity of the hippocampal axis in the assessment of its role in age-related memory decline.
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| 32. |
- Nordin, Kristin, et al.
(författare)
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Overlapping effects of age on associative memory and the anterior hippocampus from middle to older age
- 2017
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Ingår i: Behavioural Brain Research. - : Elsevier BV. - 0166-4328 .- 1872-7549. ; 317, s. 350-359
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Tidskriftsartikel (refereegranskat)abstract
- The anterior hippocampus has been implicated in associative memory, and along with hippocampal volume, this type of memory declines with age. However, few cross-sectional studies include middle-aged samples, making it unclear at what point these age-related changes occur. In addition, although men and women have been shown to differ in associative memory and rates of age-related hippocampal atrophy, sex-differences in aging are rarely studied. To address these issues, we assessed memory for word-pairs, hippocampal volume and activation during encoding and retrieval, across middle-aged (n=39) and older (n=44) participants, specifically in relation to sex. Older adults showed significantly poorer associative memory compared to middle-aged adults, paralleled by smaller anterior hippocampi and less activation during successful retrieval. The age-by-sex interaction observed in memory performance was also mirrored in the volume and activation of the hippocampus, indicating more pronounced age-effects in men as compared to women. These results indicate a specific role of the anterior hippocampus in verbal associative memory and suggest they both decline between middle-age and older age.
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| 33. |
- Nordin, Kristin, et al.
(författare)
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Structural whole-brain covariance of the anterior and posterior hippocampus : Associations with age and memory
- 2018
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Ingår i: Hippocampus. - : John Wiley & Sons. - 1050-9631 .- 1098-1063. ; 28:2, s. 151-163
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Tidskriftsartikel (refereegranskat)abstract
- The hippocampus (HC) interacts with distributed brain regions to support memory and shows significant volume reductions in aging, but little is known about age effects on hippocampal whole-brain structural covariance. It is also unclear whether the anterior and posterior HC show similar or distinct patterns of whole-brain covariance and to what extent these are related to memory functions organized along the hippocampal longitudinal axis. Using the multivariate approach partial least squares, we assessed structural whole-brain covariance of the HC in addition to regional volume, in young, middle-aged and older adults (n = 221), and assessed associations with episodic and spatial memory. Based on findings of sex differences in both memory and brain aging, we further considered sex as a potential modulating factor of age effects. There were two main covariance patterns: one capturing common anterior and posterior covariance, and one differentiating the two regions by capturing anterior-specific covariance only. These patterns were differentially related to associative memory while unrelated to measures of single-item memory and spatial memory. Although patterns were qualitatively comparable across age groups, participants' expression of both patterns decreased with age, independently of sex. The results suggest that the organization of hippocampal structural whole-brain covariance remains stable across age, but that the integrity of these networks decreases as the brain undergoes age-related alterations.
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| 34. |
- Nyberg, Lars, 1966-, et al.
(författare)
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Biological and environmental predictors of heterogeneity in neurocognitive ageing : Evidence from Betula and other longitudinal studies
- 2020
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Ingår i: Ageing Research Reviews. - : Elsevier. - 1568-1637 .- 1872-9649. ; 64
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Forskningsöversikt (refereegranskat)abstract
- Individual differences in cognitive performance increase with advancing age, reflecting marked cognitive changes in some individuals along with little or no change in others. Genetic and lifestyle factors are assumed to influence cognitive performance in aging by affecting the magnitude and extent of age-related brain changes (i.e., brain maintenance or atrophy), as well as the ability to recruit compensatory processes. The purpose of this review is to present findings from the Betula study and other longitudinal studies, with a focus on clarifying the role of key biological and environmental factors assumed to underlie individual differences in brain and cognitive aging. We discuss the vital importance of sampling, analytic methods, consideration of non-ignorable dropout, and related issues for valid conclusions on factors that influence healthy neurocognitive aging.
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| 35. |
- Persson, Jonas, et al.
(författare)
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Remembering our origin : Gender differences in spatial memory are reflected in gender differences in hippocampal lateralization
- 2013
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Ingår i: Behavioural Brain Research. - : Elsevier. - 0166-4328 .- 1872-7549. ; 256, s. 219-228
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Tidskriftsartikel (refereegranskat)abstract
- Gender differences in spatial memory favoring men are frequently reported, and the involvement of the hippocampus in these functions is well-established. However, little is known of whether this behavioral gender difference is mirrored in a gender difference in hippocampal function. Here we assessed hippocampal activity, using functional MRI, while 24 men and women moved through three-dimensional virtual mazes (navigation phase) of varying length, and at the end-point estimated the direction of the starting-point (pointing phase). Men were indeed more accurate than women at estimating direction, and this was especially true in longer mazes. Both genders activated the posterior hippocampus throughout the whole task. During the navigation phase, men showed a larger activation in the right hippocampus than women, while in the pointing phase, women showed a larger activation in the left hippocampus than men. Right-lateralized activation during the navigation phase was associated with greater task performance, and may reflect a spatial strategy that is beneficial in this task. Left-sided activation during the pointing phase might reflect a less efficient post hoc verbal recapitulation of the route. This study is the first to identify neural correlates of the commonly observed male advantage in recalling one's original position, and points to hippocampal lateralization as a possible explanation for this behavioral gender difference. (C) 2013 Elsevier B.V. All rights reserved.
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| 36. |
- Persson, Jonas, et al.
(författare)
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Sex differences in volume and structural covariance of the anterior and posterior hippocampus
- 2014
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Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; :99, s. 215-25
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Tidskriftsartikel (refereegranskat)abstract
- Sex differences in episodic and spatial memory are frequently observed, suggesting that there may be sex-related structural differences in the hippocampus (HC). Earlier findings are inconsistent, possibly due to a known variability along the hippocampal longitudinal axis. Here, we assessed potential sex differences in hippocampal volume and structural covariance with the rest of the brain in young men and women (N=76), considering the anterior (aHC) and posterior (pHC) hippocampus separately. Women exhibited a larger pHC than men adjusted for brain size. Using partial least squares, we identified two significant patterns of structural covariance of the aHC and pHC. The first included brain areas that covaried positively and negatively in volume with both the aHC and pHC in men, but showed greater covariance with the aHC than pHC in women. The second pattern revealed distinct structural covariance of the aHC and pHC that showed a clear difference between men and women: in men the pHC showed reliable structural covariance with the medial and lateral parietal lobes and the prefrontal cortex, whereas in women the aHC showed reliable structural covariance with the anterior temporal lobe bilaterally. This pattern converges with resting state functional connectivity of the aHC and pHC and suggests that these hippocampal sections interact with different brain regions, consistent with a division of labor with regards to episodic and spatial memory. Our findings lend support to a division of the HC into an anterior and posterior part and identify sex as a potential moderating factor when investigating hippocampal structure and connectivity.
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| 37. |
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| 38. |
- Rehnman, Jenny, 1971-
(författare)
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The role of gender in face recognition
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Faces constitute one of the most important stimuli for humans. Studies show that women recognize more faces than men, and that females are particularly able to recognize female faces, thus exhibiting an own-sex bias. In the present thesis, three empirical studies investigated the generality of sex differences in face recognition and the female own-sex bias. Study I explored men’s and women’s face recognition performance for Bangladeshi and Swedish female and male faces of adults and children. Result showed sex differences, favoring women, for all face categories. Study II assessed boys’ and girls’ ability to recognize female and male faces from two age- and ethnic groups. The result demonstrated that girls recognize more faces than boys do, but that no sex differences were present for Swedish male faces. The results from Study I and II consistently demonstrate that females show reliable own-sex biases independent of whether the female faces were young, old, or of Bangladeshi or Swedish origin. In an attempt to explain the mechanisms of sex differences in face recognition and the female own-sex bias, Study III investigated men’s and women’s recognition performance for androgynous faces, either labeled “men”, “women”, or “faces”. The result showed that women told to remember “women” recognized more faces than women told to remember faces labeled “men” or “faces”, and that sex differences were present for androgynous faces, regardless of the label. Based on these findings, it is suggested that females’ attention is in particular directed towards other females, resulting in an own-sex bias. It is also suggested that there may be a difference in females’ and males’ orientation toward other individuals. This difference can have a biological base, which together with socialization may result in sex differences in face recognition.
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| 39. |
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| 40. |
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