The connectivity-based architecture of the human piriform cortex
F. Zahnert,
U. Kleinholdermann,
M. Belke,
B. Keil,
K. Menzler,
D.J. Pedrosa,
L. Timmermann,
T. Kircher,
I. Nenadić,
S. Knake
Affiliations
F. Zahnert
Epilepsy Center Hesse, Department of Neurology, University Hospital Marburg, Philipps-University Marburg, Germany; Corresponding author at: Abteilung für Neurologie, Baldingerstraße, 35043 Marburg, Germany.
U. Kleinholdermann
Department of Neurology, University Hospital Marburg, Philipps University Marburg, Germany; Department of Psychiatry and Psychotherapy, University Hospital Marburg, Philipps University Marburg, Germany
M. Belke
Epilepsy Center Hesse, Department of Neurology, University Hospital Marburg, Philipps-University Marburg, Germany; Center for Personalized Translational Epilepsy Research, Goethe University Frankfurt, Germany
B. Keil
Institute of Medical Physics and Radiation Protection, Mittelhessen University of Applied Sciences, Giessen, Germany; Department of Diagnostic and Interventional Radiology, University Hospital Marburg, Philipps University of Marburg, Marburg, Germany; Center for Mind, Brain and Behavior, Philipps University Marburg, Germany
K. Menzler
Epilepsy Center Hesse, Department of Neurology, University Hospital Marburg, Philipps-University Marburg, Germany; Center for Mind, Brain and Behavior, Philipps University Marburg, Germany
D.J. Pedrosa
Department of Neurology, University Hospital Marburg, Philipps University Marburg, Germany
L. Timmermann
Department of Neurology, University Hospital Marburg, Philipps University Marburg, Germany; Center for Mind, Brain and Behavior, Philipps University Marburg, Germany
T. Kircher
Department of Psychiatry and Psychotherapy, University Hospital Marburg, Philipps University Marburg, Germany; Center for Mind, Brain and Behavior, Philipps University Marburg, Germany
I. Nenadić
Department of Psychiatry and Psychotherapy, University Hospital Marburg, Philipps University Marburg, Germany; Center for Mind, Brain and Behavior, Philipps University Marburg, Germany
S. Knake
Epilepsy Center Hesse, Department of Neurology, University Hospital Marburg, Philipps-University Marburg, Germany; Center for Personalized Translational Epilepsy Research, Goethe University Frankfurt, Germany; Center for Mind, Brain and Behavior, Philipps University Marburg, Germany; Core Facility Brain Imaging, Philipps University Marburg, Germany
The anatomy of the human piriform cortex (PC) is poorly understood. We used a bimodal connectivity-based-parcellation approach to investigate subregions of the PC and its connectional differentiation from the amygdala.One hundred (55 % female) genetically unrelated subjects from the Human Connectome Project were included. A region of interest (ROI) was delineated bilaterally covering PC and amygdala, and functional and structural connectivity of this ROI with the whole gray matter was computed. Spectral clustering was performed to obtain bilateral parcellations at granularities of k = 2–10 clusters and combined bimodal parcellations were computed. Validity of parcellations was assessed via their mean individual-to-group similarity per adjusted rand index (ARI).Individual-to-group similarity was higher than chance in both modalities and in all clustering solutions. The amygdala was clearly distinguished from PC in structural parcellations, and olfactory amygdala was connectionally more similar to amygdala than to PC. At higher granularities, an anterior and ventrotemporal and a posterior frontal cluster emerged within PC, as well as an additional temporal cluster at their boundary. Functional parcellations also showed a frontal piriform cluster, and similar temporal clusters were observed with less consistency. Results from bimodal parcellations were similar to the structural parcellations. Consistent results were obtained in a validation cohort.Distinction of the human PC from the amygdala, including its olfactory subregions, is possible based on its structural connectivity alone. The canonical fronto-temporal boundary within PC was reproduced in both modalities and with consistency. All obtained parcellations are freely available.
