Cross-species comparisons of the retrosplenial cortex in primates: Through time and neuropil space

Chronesthesia, or mental time travel (MTT), is the ability to be conscious of both past experiences and possible future scenarios. Behavioral studies have demonstrated that some non-human animals are capable of episodic-like memory, yet there exists no scientific consensus on the extent of memory abilities, including complex future thinking or planning, among non-human species. The retrosplenial cortex (Brodmann’s areas 29 and 30) plays a critical role in episodic memory, which is vital for MTT. Because MTT appears to be a uniquely human capacity, this region is of major interest for evolutionary studies. However, comparative neuroanatomical data for these regions are scarce. The goal of the present analysis was to compare neuropil space among capuchins, macaques, chimpanzees, and humans to determine if humans significantly differ from the other species. The amount of neuropil space provides a proxy measure of connectivity because a large component of the neuropil is comprised of dendrites, synapses, and axons. Digital images were analyzed using ImageJ software to obtain a neuropil fraction. The results showed significantly higher neuropil fractions in humans relative to the other species examined. Further analysis showed that this difference could not be attributed to a decrease in cell volume. These results demonstrate a unique neuroanatomical reorganization of the human retrosplenial cortex. If it is true that an increase in neuropil space is indicative of an increase in connectivity, then it may be that this is a neuroanatomical substrate that evolved to support complex mental time travel in humans.

Name thesis:degree_name

MA

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

College of Arts and Sciences / Department of Anthropology

Grantor dc:publisher

Kent State University

Year dc:date

2013

Author dc:creator

• Sumner, Mitch A.

Contributors dc:contributor

• Raghanti, Mary Ann

• Physical Anthropology
• episodic memory
• mental time travel
• neuropil
• primates
• brain
• evolution

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=kent1364987439

OAI identifier oai:identifier

oai:etd.ohiolink.edu:kent1364987439