The Corpus Callosum is the broad band of fibres that exchange signals between the two hemispheres of the brain.

The Cingulate Cortex is a narrow ‘collar’ of cortex that lies along the top of the Corpus Callosum.

The Cingulate bends under the Callosum at its anterior end. This bend is called the genu (knee) and the part of below the knee is the Subgenual Anterior Cingulate, or sgACC. The part on or around the bend or genu is termed the perigenual ACC, or pgACC.

We can divide the sgACC into anterior and posterior parts, the posterior part being at the end of the ‘collar’. Both parts of the sgACC have strong connections to limbic areas.

The anterior sgACC is mainly involved in attention and emotion processing. (Also, in recall of memory and fear memory extinction). The anterior sgACC corresponds to the top half of the reflex area.

The posterior sgACC, the bottom half of the reflex area, is thought to be homogeneous to an area of the Prefrontal Cortex called the Infralimbic PFC, and for our purposes we will regard it as such. This is involved in the regulation of the Amygdala.