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Hippocampal activity during the transverse patterning task declines with cognitive competence but not with age.

Leirer VM, Wienbruch C, Paul-Jordanov I, Kolassa S, Elbert T, Kolassa IT - BMC Neurosci (2010)

Bottom Line: Better performance in several tests of verbal memory, verbal fluency and executive function was indeed associated with higher hippocampal neural activity.Age, however, was not related to the strength of hippocampal neural activity: elderly participants responded slower than younger individuals but on average produced the same neural mass activity.Our results suggest that in non-pathological aging, hippocampal neural activity does not decrease with age but is rather related to cognitive competence.

View Article: PubMed Central - HTML - PubMed

Affiliation: Clinical Psychology & Neuropsychology, University of Konstanz, Universitätsstr, 10, Konstanz, Germany. vera.leirer@uni-konstanz.de

ABSTRACT

Background: The hippocampus is a brain region that is particularly affected by age-related morphological changes. It is generally assumed that a loss in hippocampal volume results in functional deficits that contribute to age-related cognitive decline. In a combined cross-sectional behavioural and magnetoencephalography (MEG) study we investigated whether hippocampal-associated neural current flow during a transverse patterning task - which requires learning relational associations between stimuli - correlates with age and whether it is modulated by cognitive competence.

Results: Better performance in several tests of verbal memory, verbal fluency and executive function was indeed associated with higher hippocampal neural activity. Age, however, was not related to the strength of hippocampal neural activity: elderly participants responded slower than younger individuals but on average produced the same neural mass activity.

Conclusions: Our results suggest that in non-pathological aging, hippocampal neural activity does not decrease with age but is rather related to cognitive competence.

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Source waveforms of the hippocampal sources for two age groups found by median split. Source waveforms of the hippocampal sources for the left and right hemispheres during the transverse patterning task plotted separately for the two age groups found by median split (median: 54,5 years; young group: 18-54 years; old group: 55-89 years).
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Figure 4: Source waveforms of the hippocampal sources for two age groups found by median split. Source waveforms of the hippocampal sources for the left and right hemispheres during the transverse patterning task plotted separately for the two age groups found by median split (median: 54,5 years; young group: 18-54 years; old group: 55-89 years).

Mentions: Since the RPS task was chosen as a training task in order to familiarize subjects with the transverse patterning design and the MEG environment, data analysis was solely conducted for the transverse patterning task. After noise-reduction of environmental magnetic noise (noise reduction procedure, 4 D Neuroimaging), using the reference channels of the WH2500 data were analyzed using BESA (Brain Electrical Source Analyses; MEGIS Software GmbH) software version 5.2.4.. Cardiac activity and eye movements were removed with a semi-automated procedure implemented in BESA. For each subject, epochs with a 200 ms baseline and a post trigger (stimulus presentation) window of 800 ms were generated. After baseline correction, a bandpass-filter of 1-40 Hz (Low Cutoff filter: 1 Hz, forward, 6 dB/oct; High Cutoff filter: 40 Hz, zero phase, 24 dB/oct) was applied to the resulting data epochs. Afterwards, data epochs were averaged separately for correct and incorrect trials. In order to transform surface MEG into brain source activity, a source montage with 51 fixed regional dipoles in a homogeneous sphere was defined [69]. In the case of MEG a regional dipole consists of two perpendicular, fixed equivalent current dipoles describing the two tangential components of a source, while the radial component does not contribute to the magnetic field outside the volume conductor. As we were interested in brain activity originating from hippocampal regions, the source montage consisted of 2 regional dipoles (Talairach coordinates: x = ± 42.4; y = -9.5; z = -23.9 for the right/left hemisphere) for assessing activity from the medial temporal lobes and 49 other regional dipoles that represented other brain areas, thus increasing the sensitivity of the fixed sources that had been positioned in the hippocampal region. All dipoles of the source montage were set by hand with fixed location and orientation in similar distance to the head surface to minimize differences in the sources' explanation of variance. In order to explore the time window for further analyses of dipole strength, a grand average of the correct trials of all subjects was generated. The time segment of 130-220 ms after stimulus presentation, containing the peak amplitude of the hippocampal source waveforms in both hemispheres, was chosen for further analyses (Figure 3 and 4). After selecting the time window of interest, dipole analysis was carried out on each participant. By using the source montage in the individual headframe, the mean of the norm of the dipole moment of the hippocampal-associated sources was calculated for the above-mentioned time segment per person and then analyzed statistically.


Hippocampal activity during the transverse patterning task declines with cognitive competence but not with age.

Leirer VM, Wienbruch C, Paul-Jordanov I, Kolassa S, Elbert T, Kolassa IT - BMC Neurosci (2010)

Source waveforms of the hippocampal sources for two age groups found by median split. Source waveforms of the hippocampal sources for the left and right hemispheres during the transverse patterning task plotted separately for the two age groups found by median split (median: 54,5 years; young group: 18-54 years; old group: 55-89 years).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2944355&req=5

Figure 4: Source waveforms of the hippocampal sources for two age groups found by median split. Source waveforms of the hippocampal sources for the left and right hemispheres during the transverse patterning task plotted separately for the two age groups found by median split (median: 54,5 years; young group: 18-54 years; old group: 55-89 years).
Mentions: Since the RPS task was chosen as a training task in order to familiarize subjects with the transverse patterning design and the MEG environment, data analysis was solely conducted for the transverse patterning task. After noise-reduction of environmental magnetic noise (noise reduction procedure, 4 D Neuroimaging), using the reference channels of the WH2500 data were analyzed using BESA (Brain Electrical Source Analyses; MEGIS Software GmbH) software version 5.2.4.. Cardiac activity and eye movements were removed with a semi-automated procedure implemented in BESA. For each subject, epochs with a 200 ms baseline and a post trigger (stimulus presentation) window of 800 ms were generated. After baseline correction, a bandpass-filter of 1-40 Hz (Low Cutoff filter: 1 Hz, forward, 6 dB/oct; High Cutoff filter: 40 Hz, zero phase, 24 dB/oct) was applied to the resulting data epochs. Afterwards, data epochs were averaged separately for correct and incorrect trials. In order to transform surface MEG into brain source activity, a source montage with 51 fixed regional dipoles in a homogeneous sphere was defined [69]. In the case of MEG a regional dipole consists of two perpendicular, fixed equivalent current dipoles describing the two tangential components of a source, while the radial component does not contribute to the magnetic field outside the volume conductor. As we were interested in brain activity originating from hippocampal regions, the source montage consisted of 2 regional dipoles (Talairach coordinates: x = ± 42.4; y = -9.5; z = -23.9 for the right/left hemisphere) for assessing activity from the medial temporal lobes and 49 other regional dipoles that represented other brain areas, thus increasing the sensitivity of the fixed sources that had been positioned in the hippocampal region. All dipoles of the source montage were set by hand with fixed location and orientation in similar distance to the head surface to minimize differences in the sources' explanation of variance. In order to explore the time window for further analyses of dipole strength, a grand average of the correct trials of all subjects was generated. The time segment of 130-220 ms after stimulus presentation, containing the peak amplitude of the hippocampal source waveforms in both hemispheres, was chosen for further analyses (Figure 3 and 4). After selecting the time window of interest, dipole analysis was carried out on each participant. By using the source montage in the individual headframe, the mean of the norm of the dipole moment of the hippocampal-associated sources was calculated for the above-mentioned time segment per person and then analyzed statistically.

Bottom Line: Better performance in several tests of verbal memory, verbal fluency and executive function was indeed associated with higher hippocampal neural activity.Age, however, was not related to the strength of hippocampal neural activity: elderly participants responded slower than younger individuals but on average produced the same neural mass activity.Our results suggest that in non-pathological aging, hippocampal neural activity does not decrease with age but is rather related to cognitive competence.

View Article: PubMed Central - HTML - PubMed

Affiliation: Clinical Psychology & Neuropsychology, University of Konstanz, Universitätsstr, 10, Konstanz, Germany. vera.leirer@uni-konstanz.de

ABSTRACT

Background: The hippocampus is a brain region that is particularly affected by age-related morphological changes. It is generally assumed that a loss in hippocampal volume results in functional deficits that contribute to age-related cognitive decline. In a combined cross-sectional behavioural and magnetoencephalography (MEG) study we investigated whether hippocampal-associated neural current flow during a transverse patterning task - which requires learning relational associations between stimuli - correlates with age and whether it is modulated by cognitive competence.

Results: Better performance in several tests of verbal memory, verbal fluency and executive function was indeed associated with higher hippocampal neural activity. Age, however, was not related to the strength of hippocampal neural activity: elderly participants responded slower than younger individuals but on average produced the same neural mass activity.

Conclusions: Our results suggest that in non-pathological aging, hippocampal neural activity does not decrease with age but is rather related to cognitive competence.

Show MeSH
Related in: MedlinePlus