Parcellation of the Hippocampus According to Its Connection Probability with Prefrontal Cortex Subdivisions in a Malaysian Malay Population: Preliminary Findings.

Aimi Nadhiah Abdullah,Sofina Tamam,Jafri Malin Abdullah,Asma Hayati Ahmad,Rahimah Zakaria

doi:10.21315/mjms2021.28.3.6

Abstract

BackgroundLesion studies have shown distinct roles for the hippocampus, with the dorsal subregion being involved in processing of spatial information and memory, and the ventral aspect coding for emotion and motivational behaviour. However, its structural connectivity with the subdivisions of the prefrontal cortex (PFC), the executive area of the brain that also has various distinct functions, has not been fully explored, especially in the Malaysian population.MethodsWe performed diffusion magnetic resonance imaging with probabilistic tractography on four Malay males to parcellate the hippocampus according to its relative connection probability to the six subdivisions of the PFC.ResultsOur findings revealed that each hippocampus showed putative connectivity to all the subdivisions of PFC, with the highest connectivity to the orbitofrontal cortex (OFC). Parcellation of the hippocampus according to its connection probability to the six PFC subdivisions showed variability in the pattern of the connection distribution and no clear distinction between the hippocampal subregions.ConclusionHippocampus displayed highest connectivity to the OFC as compared to other PFC subdivisions. We did not find a unifying pattern of distribution based on the connectivity-based parcellation of the hippocampus.

Highlights

The hippocampus, a medial temporal lobe structure found in all species of mammals, plays a key role in spatial navigation as well as in various modes of learning and memory [1– 3]
Lesion studies have shown that tasks usually associated with the hippocampus are mostly subserved by its dorsal subregion, while the ventral hippocampus is more involved in emotional and motivational behaviours such as anxiety [6]
The biggest mask was the one for the dorsolateral prefrontal cortex (DLPFC); right side, mean [SD] = 29,659.00 [5,482.86]) and the smallest was the one for hippocampus

Summary

Introduction

The hippocampus, a medial temporal lobe structure found in all species of mammals, plays a key role in spatial navigation as well as in various modes of learning and memory [1– 3]. The hippocampus is divided into many subfields including the regions of dentate gyrus and cornum ammonis areas 1 and 3. It is arranged along a longitudinal axis that stretches from an anterior to a posterior pole in primates, as well as in humans [5]. Lesion studies have shown that tasks usually associated with the hippocampus (i.e. the processing of spatial information and memory) are mostly subserved by its dorsal subregion, while the ventral hippocampus is more involved in emotional and motivational behaviours such as anxiety [6]. Lesion studies have shown distinct roles for the hippocampus, with the dorsal subregion being involved in processing of spatial information and memory, and the ventral aspect coding for emotion and motivational behaviour. Its structural connectivity with the subdivisions of the prefrontal cortex (PFC), the executive area of the brain that has various distinct functions, has not been fully explored, especially in the Malaysian population

Methods

Results

Discussion

Conclusion