Table 2.
Proposed DBS Effects on Structures and Circuits Within the Limbic Basal Ganglia Pathways
| Structure/Circuit | Function | Proposed DBS Effect |
|---|---|---|
| Limbic-Motor Association | Fibers in the genu that connect to VII and when stimulated lead to a contralateral limbic smile | Contralateral limbic smile |
| Accumbens | Reward Center; Calculates probability and magnitude of expected reward and decides to initiate movement | Output fibers may activate limbic smile |
| Modulates excitatory input from subiculum, prefrontal cortex and amygdala | Output tract VII, OFC/cingulate Possible OCD/Depression/Anxiety benefit | |
| Orbitofrontal Cortex (OFC) | Facial emotional expressions, probable connection with accumbens in basal ganglia non-motor loop | Happiness, Giddiness |
| Cingulate Cortex | Assigns reward value to gustatory, olfactory, auditory, somatosensory stimuli | Potential to give feedback for smile |
| Involved in the emotion of winning or losing money; Cingulate also with facial areas—output to capsule | ||
| Medial Olfactory Stria | Axons from olfactory tract pass through on their way to medial or lateral olfactory areas | Olfactory/Gustatory Hallucination |
| Olfactory input may enter this area prior to crossing the anterior commissure to contralateral olfactory bulb | ||
| Anterior Commissure | Rostral olfactory portion—connects to anterior olfactory nucleus | Olfactory/Gustatory Hallucination |
| Caudal temporal portion—connects to bed nucleus, amygdala, temporal isocortex | ||
| There are both axons and neurons in anterior commissure; can be integration of impulses | ||
| Anterior Hypothalamus | Indistinct group of cells between supraoptic and paraventricular nucleus | Nausea |
| Nucleus Tractus Solitarious connects to central pattern generator to medulla and hypothalamus | Potential changes in heart rate, BP | |
| Anterior Limb | Fibers may connect to orbitofrontal or cingulate cortex through nonmotor basal ganglia loops | Possible OCD benefit |
| May be fronto-pontine connections | ||
| Internal Capsule | Probable connections to anterior genu and corticobulbar fibers (fibers from cingulate facial areas) | Possible anxiety/depression benefit Facial Fibers of VII |
| Probable connection to nucleus accumbens | ||
| Potential Fibers to OFC/Cingulate |