Recent neuroimaging research indicates that people with OCD show increased levels of grey matter in the _____ and the _____ relative to those who do not have OCD.

1)splenium; corpus collosum
2)locus ceruleus; hypothalamus
3)thalamus; left frontal cortex
4)thalamus; right temporal cortex

To determine the correct answer, we can break it down and look at recent neuroimaging research on OCD. Neuroimaging techniques such as magnetic resonance imaging (MRI) are commonly used to study the brain and identify structural differences. In this case, researchers have found that people with OCD tend to exhibit increased levels of grey matter in certain areas compared to those without OCD.

Let's examine each answer choice and see if it aligns with recent findings:

1) Splenium; corpus collosum: The splenium is a part of the corpus collosum, which connects the two hemispheres of the brain. While there might be structural differences associated with OCD, recent research does not specifically suggest increased grey matter in this region.

2) Locus ceruleus; hypothalamus: The locus ceruleus is a small region in the brainstem involved in regulating arousal and stress response. The hypothalamus is responsible for numerous functions, including hormone secretion and behavior regulation. Although it's possible that changes in these regions could be associated with OCD, recent findings do not indicate increased levels of grey matter specifically in these areas.

3) Thalamus; left frontal cortex: The thalamus serves as a relay station for sensory information and is linked to various brain functions. The frontal cortex, specifically the left frontal cortex, is associated with executive functions and decision-making processes. Recent studies have indeed found increased levels of grey matter in the thalamus and left frontal cortex of individuals with OCD, making this a plausible answer.

4) Thalamus; right temporal cortex: As mentioned above, the thalamus has been implicated in OCD research. The right temporal cortex is involved in language, memory, and emotional processing. Although there might be changes in these regions associated with OCD, recent research does not indicate increased levels of grey matter specifically in the right temporal cortex.

Based on recent neuroimaging studies, the most accurate answer choice is option 3) thalamus; left frontal cortex.