Cerebellum

Anatomy

• In the posterior cranial fossa, below the tentorium cerebelli; the vermis in the midline and two hemispheres. Anterior, posterior and flocculonodular lobes; folia.
• Cortex: molecular, Purkinje and granular layers. Deep nuclei: dentate, interposed (emboliform + globose), fastigial.
• Peduncles: superior (output — dentato-rubro-thalamic), middle (pontine input), inferior (spinal and olivary input).
• About 80% of the brain’s neurons (granule cells) are here. Blood supply: SCA, AICA, PICA.

Substructures

11 substructures; each has its own page.

Surface parts (lobules)

• Anterior Lobe (Lobules I–V) I–VThe sensorimotor anterior lobe of the cerebellum: the first somatotopic map of the trunk and limbs; regulates gait and posture.
• Lobule VI VIA transitional lobule between sensorimotor and cognitive regions: active in movement, language and attention tasks.
• Crus I Crus IThe cognitive core of the cerebellum: forms loops with prefrontal and parietal cortex and supports executive function and language.
• Crus II Crus IIA posterior lobe region involved in social and cognitive processing: connected with mentalizing and executive networks.
• Lobule VIIb VIIbA posterior lobe lobule between Crus II and lobule VIII, connected with attention and working memory networks.
• Lobule VIII (VIIIa–VIIIb) VIIIThe lobule carrying the second sensorimotor body map; also connected with attention networks.
• Lobule IX (Tonsil) IXA posterior lobe region connected with the default mode network; its hemispheric part is the cerebellar tonsil.
• Flocculonodular Lobe (Lobule X) XThe vestibulocerebellum: regulates balance, eye–head coordination and holding gaze steady.
• Posterior Vermis (Lobules VI–IX) VermisThe midline “limbic cerebellum”: linked to emotion regulation, eye movements and autonomic responses.

Inner structures (deep nuclei)

• Dentate Nucleus DNThe largest deep cerebellar nucleus: carries the output of the lateral hemispheres via the thalamus to motor and prefrontal cortex.
• Interposed Nucleus (Emboliform and Globose) IPThe output of the paravermal region: corrects limb movements on the fly; plays a role in conditioned eyeblink learning.

Functions

• Motor coordination, balance and posture (vermis, flocculonodular lobe).
• Timing and prediction of movement (internal models), motor learning.
• Eye movements and adaptation of the vestibulo-ocular reflex.
• Cognitive functions: the lateral posterior hemispheres (Crus I/II) form loops with the PFC — working memory, language, timing.
• Emotional regulation (posterior vermis — the “limbic cerebellum”), social cognition.

Connections and chemistry

• Pons (corticopontocerebellar input)
• Inferior olive (climbing fibers)
• Dentate → thalamus VL → motor and prefrontal cortex
• Red nucleus
• Vestibular nuclei

Development

Developmental course through childhood and adolescence.

• Grows very rapidly in the last trimester and the first years; its volume increases by about 240% in the first year (Knickmeyer et al., 2008).
• Peak volume comes later than in the cortex, in adolescence (Tiemeier et al., 2010).
• Cerebellar injury after preterm birth has been linked to positive ASD screening (Limperopoulos et al., 2007).

Clinical

• ASD: postmortem loss of Purkinje cells, vermis hypoplasia; early cerebellar injury has been proposed as one of the strongest risk factors (Wang, Kloth & Badura, 2014).
• ADHD: reduced posterior-inferior vermis volume, timing difficulties.
• Posterior fossa syndrome (cerebellar mutism): developed in 24% of 450 children after medulloblastoma surgery; preoperative brainstem involvement was the only risk factor. At one year, speech-language and cognitive problems and ataxia persisted in a large share (Robertson et al., 2006). A
• Cerebellar cognitive affective syndrome (Schmahmann).
• Joubert syndrome (the “molar tooth” sign), FASD (vermis), “cognitive dysmetria” in schizophrenia (Andreasen).
• Negative symptoms in schizophrenia: the weaker the connectivity between the right DLPFC and the cerebellum, the more severe the negative symptoms; in 11 patients, 5 days of TMS to the vermis (lobule VIIb) restored connectivity, and the increase related to symptom improvement (Brady et al., 2019). A later sham-controlled study found no difference between arms (Basavaraju et al., 2021; 60 patients; connectivity increased, symptoms improved in both arms); the target is promising but not proven. C

Treatment

This region from the perspective of medication, psychotherapy and neuromodulation. Letter badges are evidence levels.

• In posterior fossa syndrome: intensive speech-language therapy and neuropsychological rehabilitation; families are told that the mutism is temporary. B
• Cerebellar TMS (vermis) for negative symptoms in schizophrenia is investigational (Brady et al., 2019). C
• In ASD and ADHD the cerebellum is not a treatment target; occupational therapy for motor and timing difficulties.

Assessment

Neuropsychological tasks and measures that probe this region's function.

• Finger–nose, heel–shin, rapid alternating movements (dysdiadochokinesia)
• Tandem gait, Romberg
• Rhythm and timing tasks; eyeblink conditioning

Lesions and damage

Clinical findings expected with damage or dysfunction.

• Ipsilateral ataxia, dysmetria, intention tremor, dysdiadochokinesia, nystagmus, scanning dysarthria, hypotonia.
• Vermis: truncal ataxia.
• Posterior lobe: executive, visuospatial, language and affective disturbances (flat affect, disinhibition).

In the model

How this structure is defined in the 3D model, and the data source.

CerebrA cerebellar gray and white matter and vermis labels. Folia are not distinct in the average template. When selected, the surface is colored by SUIT lobules (Diedrichsen et al., 2009); the dentate and interposed nuclei lie inside. The fastigial nucleus is not shown because it is only a few voxels in the atlas’s most-probable label map.

References

Full citations for the card; links go to the paper (DOI) or a PubMed search.

1. Robertson PL et al. Incidence and severity of postoperative cerebellar mutism syndrome in children with medulloblastoma: a prospective study by the Children's Oncology Group. J Neurosurg 2006;105(6 Suppl):444–451. Search PubMed
2. Brady RO et al. Cerebellar-prefrontal network connectivity and negative symptoms in schizophrenia. Am J Psychiatry 2019;176(7):512–520. Search PubMed