Orbitofrontal sulcogyral morphology in patients with cocaine use disorder

Abstract

Orbitofrontal cortex (OFC) is thought to be involved in appropriate processing of rewarding stimuli, and abnormal OFC structure and function has been found in patients with substance use disorders. Atypical patterns of the H-sulcus in the OFC have been primarily identified with schizophrenia, but also with bipolar disorder, both of which are associated with comorbid substance use. Given the high rates of substance use within Axis I psychiatric disorders, it is reasonable to consider how frequencies of OFC patterns in populations with only substance use compare to controls. This information is crucial to disentangle whether atypical frequencies of H-sulcus sulcogyral patterns within psychopathology are associated with the psychiatric or substance use phenotype. Here, we present the first analysis of H-sulcus sulcogyral patterns in a population of adult black men with (n = 84) and without (n = 24) cocaine use disorder (CUD). We find that OFC sulcogyral patterns are not significantly different from the control group, indicating that OFC sulcogyral patterns are not disrupted in patients with CUD. As exploratory analyses, we describe OFC sulcogyral pattern subtypes in this cohort as well as an additional control group (n = 52), in order to add to the growing body of literature on OFC sulcogyral pattern characterization.

Keywords: Gyrification; OFC; Sulcus; Ventromedial prefrontal cortex.

Fig. 1.. Depictions of each pattern type.

Axial slices from the right hemisphere T1 image of example subjects depicting each pattern type, with tracing overlaid to illustrate each sulcus. Type I pattern is distinguished by its discontinuous Medial Orbital Sulcus (MOS) and continuous Lateral Orbital Sulcus (LOS). Type II is defined by a continuous MOS and LOS. Type III is distinguished by a discontinuous MOS and discontinuous LOS. Type IV is defined by a continuous MOS and discontinuous LOS. Red line indicates MOS. Blue line indicates LOS. Yellow line indicates Transverse Orbital Sulcus (TOS). Green line indicates Intermediate Orbital Sulcus (IOS). Pink line indicates orientation of the orbitofrontal cortex from the sagittal plane.

Fig. 2.. Frequency distributions for pattern types.

Pattern frequencies plotted for each pattern Type across all hemispheres (top panel) and for the left and right hemispheres (bottom panel). Black bar indicates cocaine use patient group, gray bar indicates no cocaine use group, and white bar indicates independent control group. Frequencies of pattern type for each group add up to a total frequency of 1. Please note that within the same participant, pattern types may differ between the left and right hemisphere.

Fig. 3.. Sulcogyral pattern subtype variation for all patients and controls.

Pattern Type cartoon exemplar on left for each of four panels, depicting a canonical pattern for each Type. Individual subtypes are labeled with letters, with the first 6 letters (A-F) matching the original pattern subtypes identified by Chiavaras and Petrides for pattern Types I, II, and III. Note that in this original descriptive paper, pattern Type IV (and corresponding subtypes) were not identified and therefore not included. Any new subtypes that we identified for pattern Types I, II, and III were labeled with the next alphabetical letter. Please note that not all previously identified pattern subtypes were identified in the sample described here, as reflected in the frequency graphs. See supplementary figures and descriptions for complete description of methods and individual cartoon examplars and descriptions of each pattern subtype.