Table 3.

Neuroimaging findings

Source	Imaging technique	Paradigm/analysis method	Contrast of interest	Hemisphere	Brain area
1. Abé et al. (2014)	MRI2	Cortical thickness	HeM > HoM	R	Inferior temporal gyrus
				R	Lateral orbitofrontal cortex
				R	Pars triangularis
				R	Lingual gyrus
				R	Cuneus
				R	Pericalcarine cortex
		Subcortical volumes	HeM > HoM	L	Thalamus
				R	Thalamus
2. Burke et al. (2017)	MRI/DTI2	Fractional anisotropy	HoM & HoF vs. HeM & HeF		ns
3. Eckstrand et al. (2019)	fMRI1	Brain activation during social reward task (perception of being liked)	Sexual minorities < heterosexuals (positive > neutral feedback)	R	Medial prefrontal cortex
				L	Anterior insula
				R	Temporoparietal junction
		Brain activation during monetary reward	Sexual minorities vs. heterosexuals (reward anticipation > neutral)		ns
		Negative correlation between depression scores and brain activation during social reward task	Sexual minorities < heterosexuals (positive > neutral feedback)	R	Temporoparietal junction
		Positive correlation between depression scores and brain activation during social reward task	Sexual minorities < heterosexuals (positive > neutral feedback)	L	Anterior insula
4. Folkierska-Żukowska et al. (2020)	fMRI1	ROI activation (mental rotation task vs. baseline)	GC HoM vs. GC HeM		ns
			GNC HoM < GC HeM	R	Angular gyrus
				R	Middle temporal gyrus
				L	Middle temporal gyrus
5. Hu et al. (2013)	fMRI1	Resting state; ReHo	HoM > HeM	L	Rectal gyrus
				L	Midbrain
				R	Midbrain
				L	Temporal lobe
				R	Extranuclear white matter
			HoM < HeM	L	Inferior occipital gyrus
				R	Middle occipital gyrus
				L	Cuneus
				R	Superior occipital gyrus
				R	Precuneus
		Resting state; functional connectivity of left inferior occipital gyrus (seed)	HoM < HeM	L	Middle temporal gyrus
				L	Supramarginal gyrus
				L	Inferior occipital gyrus
				R	Cuneus
6. Hu et al., (2014)	fMRI1	Resting state; fALFF	HoM > HeM	R	Anterior cerebellar lobe
				R	Middle frontal gyrus
				L	Inferior parietal gyrusa
			HoM < HeM	L	Postcentral gyrus
				L	Lingual gyrus
				R	Pallidum
				R	Postcentral gyrus
				R	Superior temporal gyrus
				L	Cuneus
				L	Inferior frontal gyrus
		Resting state; functional connectivity of the left postcentral gyrus (seed)	HoM < HeM	R	Precuneus
				L	ACC
				L	Cuneus
				R	Putamen
				R	Middle temporal gyrus
				L	Lingual gyrus
				L	Gyrus rectus
		Resting state; functional connectivity of the left cuneus (seed)	HoM < HeM, *indicates significant positive correlation with sexual orientation	R	Paracentral lobule
				L	Superior parietal gyrus*
				L	Postcentral gyrus
				R	Precentral gyrus
				L	Middle cingulate cortex
				L	Inferior parietal gyrus
				R	Postcentral gyrus
7. Kinnunen et al. (2004)	PET1	Metabolic changes after administration of 40 mg fluoxetine as compared to placebo	HoM > HeM smaller decrease in glucose metabolism in response to fluoxetine relative to placebo		Hypothalamus
			HoM > HeM greater increase in glucose metabolism in response to fluoxetine relative to placebo		Prefrontal association cortex
					Cingulate cortex
			HoM < HeM greater increase in glucose metabolism in response to fluoxetine relative to placebo		Lateral anterior cingulate
					Hippocampus/parahippocampal gyrus
					Cuneate gyrus
8. Manzouri and Savic (2018a)	MRI2	Cortical thickness	HoM < HeM	R	Cuneus
			HoM > HeM	L	Precuneus
			HoM > HeM	R	Rostral-anterior cingulate
			HoF vs. HeF		ns
		Subcortical volume	HoM & HoF vs. HeM & HeF		ns
	fMRI1	Resting state; functional connectivity of the DMN	HoM & HoF < HeM & HeF		mPFC/ACC
					Precuneus
	DTI2	Fractional anisotropy	HoM & HoF vs. HeM & HeF		ns
9. Manzouri & Savic (2018b)	MRI2	Cortical thickness	HoM > HeM	R	ACC
				R	Superior frontal gyrus
				R	Precuneus
				L	Occipito-temporal cortex
				L	Superior parietal cortex
			HoM < HeM	R	Cuneus
		Cortical thickness; covariation in cortical thickness of precuneus (seed)	HoM > HeM		ACC
					Mid cingulate
					Occipital cortex
					Inferior frontal cortex
					Insular cortex
		Surface area	HoM < HeM	L	Cuneus
		Subcortical volume	HoM vs. HeM		ns
	fMRI1	Resting state; functional connectivity of the DMN	HoM < HeM		Posterior cingulate and precuneus
		Resting state; functional connectivity of the left thalamus (seed)	HoM > HeM	L	Mediodorsal thalamus nucleus, anterior hypothalamus
		Resting state; functional connectivity of the right thalamus (seed)	HoM > HeM	R	Mediodorsal thalamus nucleus, left pulvinar, anterior hypothalamus
		Resting state; functional connectivity of the hypothalamus (seed)	HoM vs. HeM		ns
10. Ponseti et al. (2007)	MRI2	Global brain volume	HoM > HeM		Cerebrospinal fluid
			HoF vs. HeF		ns
		Regional grey matter volume	HoM vs. HeM		ns
			HoF < HeF	L	Perirhinal cortex
				L	Ventral premotor cortex
				L	Cerebellum
				R	Cerebellum
				R	Perirhinal cortex
11. Savic & Lindström (2008)	PET1	Resting state; functional connectivity of the left amygdala (seed)	HoM > HeM		ACC
				R	Amygdala/ insula
				L	Parahippocampus
			HoM < HeM	L	Parietal cortex/ posterior cingulate cortex
			HoF < HeF	R	Anterior cingulate (subcallosum)
				R	Amygdala/ insula
			HoF > HeF		ns
		Resting state; functional connectivity of the right amygdala (seed)	HoM > HeM		ACC
					Hypothalamus + portion of left amygdala
			HoM < HeM		ns
			HeF > HoF	L	Amygdala
			HoF > HeF	L	Frontopolar cortex
				R	Parietal cortex
	MRI2	Hemisphere volume asymmetry	HeM and HoF had significant hemisphere asymmetry as compared to HoM and HeF who did not have asymmetry.
12. Wang et al. (2020)	MRI/DTI2	Anatomical connectome analysis	HoM < HeM	L	Connectivity between left postcentral gyrus and left supramarginal gyrus
13. Witelson et al. (2008)	MRI2	Corpus callosum volume	HoM > HeM		ns (trending) isthmus

HeM = heterosexual males; HeF = heterosexual females; HoM = homosexual males; HoF = homosexual females. GNC = gender non-conforming, GC = gender conforming, ACC = anterior cingulate cortex, mPFC = medial prefrontal cortex, DMN= default mode network. ¹Denotes functional neuroimaging results. ²Denotes structural neuroimaging results. ^aCoding based on results presented in Figure 2/Table 2 in Hu et al. (2014).