Basic Neuroscience · Neuroanatomy
Basal Ganglia & Brainstem Nuclei
Basal ganglia circuitry plus the key deep grey-matter and brainstem nuclei, and the cerebellar fiber components.
Summary of the basal ganglia
- Putamen and caudate are the input nuclei.
- Globus pallidus (GP) is the main output nucleus.
- SNpc → dopaminergic fibers to the putamen.
- STN receives inhibitory fibers from GPe and sends excitatory fibers to GPi.
Basal ganglia nuclei
| Nucleus | Role | Connections / clinical |
|---|---|---|
| Caudate | Movement processing; cognitive executive functions; working memory, learning and language; responds to visual beauty (neural correlate for romantic love) | Dorsolateral prefrontal cortex → dorsolateral caudate → dorsomedial nucleus of thalamus → back to prefrontal cortex |
| STN | Part of the indirect (inhibitory) loop of the BG (sends glutamatergic fibers to stimulate GPi) | Lesion → hemiballismus, impulsivity |
| GP | Main output nucleus | Input from putamen and STN (no direct cortical afferent) |
Other brain & brainstem nuclei
| Nucleus | Function |
|---|---|
| Amygdala | Limbic system — memory, emotions and decision-making. Efferents via 3 pathways: (1) stria terminalis (main) from medial nucleus → nucleus of stria terminalis → thalamus & hypothalamus; (2) amygdalofugal from lateral nucleus → thalamus (dorsomedial nucleus), hypothalamus, BG and brainstem; (3) anterior commissure → opposite temporal lobe |
| Nucleus accumbens | Anticipating reward and habit formation |
| Red nucleus | Motor coordination (mainly shoulder and upper arm), arm movements during walking/crawling, movement initiation |
| Locus ceruleus | Located in pons. Reaction to stress and panic, attention and memory. Principal site for brain synthesis of norepinephrine |
| Nucleus basalis of Meynert | Basal forebrain; principal site for brain synthesis of ACh. Widespread projections to neocortex; lesion → marked decrease in mental capacity and learning (Alzheimer and PD) |
| Raphe nuclei | Medial brainstem from medulla to pons. Major source of serotonin; involved in sleep–wake cycle and circadian rhythm |
Cerebellar components
| Fiber | Description |
|---|---|
| Mossy fibers | From DSCT, CCT, VCT & PCT; on reaching the cerebellum form mossy fibers that terminate in granular cells, which project to Purkinje cells (indirect) |
| Climbing fibers | Glutamatergic fibers from the inferior olivary nucleus → Purkinje cells (direct) |
| Purkinje fibers | The only fibers that project from cerebellar cortex to cerebellar nuclei |
LIGHTS on RITE by Ahmed Koriesh