A (sub)field guide to quality control in hippocampal subfield segmentation on high-resolution T-weighted MRI.

Inquiries into properties of brain structure and function have progressed due to developments in magnetic resonance imaging (MRI). To sustain progress in investigating and quantifying neuroanatomical details in vivo, the reliability and validity of brain measurements are paramount. Quality control (QC) is a set of procedures for mitigating errors and ensuring the validity and reliability of brain measurements.

The Effect of Segmentation Method on Medial Temporal Lobe Subregion Volumes in Aging.

Early stages of Alzheimer's disease (AD) are associated with volume reductions in specific subregions of the medial temporal lobe (MTL). Using a manual segmentation method-the Olsen-Amaral-Palombo (OAP) protocol-previous work in healthy older adults showed that reductions in grey matter volumes in MTL subregions were associated with lower scores on the Montreal Cognitive Assessment (MoCA), suggesting atrophy may occur prior to diagnosis of mild cognitive impairment, a condition that often progresses to AD. However, current "gold standard" manual segmentation methods are labour intensive and time consuming.

Impaired perceptual discrimination of complex objects in older adults at risk for dementia.

Tau pathology accumulates in the perirhinal cortex (PRC) of the medial temporal lobe (MTL) during the earliest stages of the Alzheimer's disease (AD), appearing decades before clinical diagnosis. Here, we leveraged perceptual discrimination tasks that target PRC function to detect subtle cognitive impairment even in nominally healthy older adults. Older adults who did not have a clinical diagnosis or subjective memory complaints were categorized into "at-risk" (score <26; n = 15) and "healthy" (score ≥26; n = 23) groups based on their performance on the Montreal Cognitive Assessment.

The impact of aging and repetition on eye movements and recognition memory.

The modulation of gaze fixations on neural activity in the hippocampus, a region critical for memory, has been shown to be weaker in older adults compared to younger adults. However, as such research has relied on measures of memory, it remains unclear whether the relationship between visual exploration and measures of memory is similarly disrupted in aging. The current study tested older and younger adults on a face memory eye-tracking task previously used by our group that showed that recognition memory for faces presented across variable, but not fixed, viewpoints relies on a hippocampal-dependent binding function.