INS NYC 2024 Program

Poster	Poster Session 04 Program Schedule 02/15/2024 12:00 pm - 01:15 pm Room: Shubert Complex (Posters 1-60) Poster Session 04: Neuroimaging \| Neurostimulation/Neuromodulation \| Teleneuropsychology/Technology Final Abstract #55 Hippocampal Subfields Mediate Differential Effects of Age on Pattern Separation and Recognition Memory Savana Jurgens, The Ohio State University, Columbus, United States Michael Melville, The Ohio State University, Columbus, United States Ann Lee, The Ohio State University, Columbus, United States Erica Howard, The Ohio State University, Columbus, United States Scott Hayes, The Ohio State University, Columbus, United States Jasmeet Hayes, The Ohio State University, Columbus, United States Category: Aging Keyword 1: neuroimaging: structural Keyword 2: aging (normal) Keyword 3: hippocampus Objective: Pattern separation and recognition memory are integral to the encoding, storage, and retrieval of information. These processes have been linked to the hippocampus, a region composed of several subfields which differentially contribute to memory function. More specifically, the dentate gyrus (DG) is critical to pattern separation, the process by which similar, yet discreet, stimuli are made more distinct at encoding. By contrast, the CA3 is recruited for recognition memory, or the ability to determine whether stimuli have been previously encountered. Recent studies have demonstrated that decline in these memory facets over the lifespan may be explained by age-related changes in hippocampal subfields. The purpose of this study was to examine whether DG and CA3 morphometry explain age-dependent decline in pattern separation and recognition memory, respectively. Participants and Methods: Data were obtained from the Fitness, Aging, Stress, TBI Exposure Repository (FASTER) and included 80 participants aged 19-86 years. Participants completed the Mnemonic Similarity Task (MST; Stark et al., 2013) which tests the ability to discriminate between similar objects and recognize previously seen objects. Raw data from this task were used to generate a measure of pattern separation known as the Lure Discrimination Index (LDI), as well as an index of Recognition Memory. Participants then underwent structural imaging where a whole-brain T1-weighted (T1w) scan and a high-resolution T2-weighted (T2w) scan of the medial temporal lobes were obtained. Data were processed through FreeSurfer’s automated hippocampal subfield segmentation program, providing volume estimates for the CA3 and DG. Subfield volumes were adjusted for estimated intracranial volume (eICV) prior to analysis. The PROCESS macro (Hayes, 2013) was then used to examine whether the DG and CA3 act as indirect pathways linking age to deficits in pattern separation and recognition memory, respectively. Analyses were adjusted for sex and years of education. Results: Results indicated that DG volume mediates the relationship between age and LDI scores (B =-0.074, SE = 0.038, Bootstrapped 95% CI [-0.154, -0.008]), such that older age was associated with lower DG volume which in turn was associated lower LDI scores. By contrast, the mediating effect of CA3 volume on the relationship between age and recognition memory was not significant (B =-0.0009, SE = 0.032, Bootstrapped 95% CI [-0.080, 0.057]). Further examination of these relationships revealed there was no effect of age on recognition memory (B =0.009, SE = 0.115, Bootstrapped 95% CI [-0.219, 0.238]) or CA3 volume (B =-0.183, SE = 0.107, Bootstrapped 95% CI [-0.397, 0.031]). Conclusions: The results demonstrate that age-related decline in pattern separation is mediated through DG volume. Specifically, age was associated with reduced DG volume and in turn lower pattern separation performance. By contrast, age effects on CA3 volume and recognition memory were not observed. These findings highlight that the ability to discriminate between overlapping representations may become impaired with age while the ability to recognize familiar information is spared. Future work may examine whether these findings translate to early clinical markers of neurodegenerative disease.

Poster

02/15/2024
12:00 pm - 01:15 pm
Room: Shubert Complex (Posters 1-60)

Poster Session 04: Neuroimaging | Neurostimulation/Neuromodulation | Teleneuropsychology/Technology

Final Abstract #55

Hippocampal Subfields Mediate Differential Effects of Age on Pattern Separation and Recognition Memory

Savana Jurgens, The Ohio State University, Columbus, United States
Michael Melville, The Ohio State University, Columbus, United States
Ann Lee, The Ohio State University, Columbus, United States
Erica Howard, The Ohio State University, Columbus, United States
Scott Hayes, The Ohio State University, Columbus, United States
Jasmeet Hayes, The Ohio State University, Columbus, United States

Category: Aging

Keyword 1: neuroimaging: structural
Keyword 2: aging (normal)
Keyword 3: hippocampus

Objective:

Pattern separation and recognition memory are integral to the encoding, storage, and retrieval of information. These processes have been linked to the hippocampus, a region composed of several subfields which differentially contribute to memory function. More specifically, the dentate gyrus (DG) is critical to pattern separation, the process by which similar, yet discreet, stimuli are made more distinct at encoding. By contrast, the CA3 is recruited for recognition memory, or the ability to determine whether stimuli have been previously encountered. Recent studies have demonstrated that decline in these memory facets over the lifespan may be explained by age-related changes in hippocampal subfields. The purpose of this study was to examine whether DG and CA3 morphometry explain age-dependent decline in pattern separation and recognition memory, respectively.

Participants and Methods:

Data were obtained from the Fitness, Aging, Stress, TBI Exposure Repository (FASTER) and included 80 participants aged 19-86 years. Participants completed the Mnemonic Similarity Task (MST; Stark et al., 2013) which tests the ability to discriminate between similar objects and recognize previously seen objects. Raw data from this task were used to generate a measure of pattern separation known as the Lure Discrimination Index (LDI), as well as an index of Recognition Memory. Participants then underwent structural imaging where a whole-brain T1-weighted (T1w) scan and a high-resolution T2-weighted (T2w) scan of the medial temporal lobes were obtained. Data were processed through FreeSurfer’s automated hippocampal subfield segmentation program, providing volume estimates for the CA3 and DG. Subfield volumes were adjusted for estimated intracranial volume (eICV) prior to analysis. The PROCESS macro (Hayes, 2013) was then used to examine whether the DG and CA3 act as indirect pathways linking age to deficits in pattern separation and recognition memory, respectively. Analyses were adjusted for sex and years of education.

Results:

Results indicated that DG volume mediates the relationship between age and LDI scores (B =-0.074, SE = 0.038, Bootstrapped 95% CI [-0.154, -0.008]), such that older age was associated with lower DG volume which in turn was associated lower LDI scores. By contrast, the mediating effect of CA3 volume on the relationship between age and recognition memory was not significant (B =-0.0009, SE = 0.032, Bootstrapped 95% CI [-0.080, 0.057]). Further examination of these relationships revealed there was no effect of age on recognition memory (B =0.009, SE = 0.115, Bootstrapped 95% CI [-0.219, 0.238]) or CA3 volume (B =-0.183, SE = 0.107, Bootstrapped 95% CI [-0.397, 0.031]).

Conclusions:

The results demonstrate that age-related decline in pattern separation is mediated through DG volume. Specifically, age was associated with reduced DG volume and in turn lower pattern separation performance. By contrast, age effects on CA3 volume and recognition memory were not observed. These findings highlight that the ability to discriminate between overlapping representations may become impaired with age while the ability to recognize familiar information is spared. Future work may examine whether these findings translate to early clinical markers of neurodegenerative disease.