cerebellum and its function with relevance to psychiatry

1. CEREBELLUM-ITS
FUNCTION AND
RELEVANCE IN
PSYCHIATRY

3. The cerebellum, which lies just dorsal to the pons and medulla, consists of two highly
convoluted lateral cerebellar hemispheres and a narrow medial portion, the vermis. It is
connected to the brain by three pairs of dense fiber bundles called the peduncles.

4. CEREBELLAR STRUCTURE

5. CEREBELLAR CIRCUIT
Cerebellum receives inputs from the spinal cord and from many
regions of both the cortical and subcortical brain.
In this way, the cerebellum receives extensive information from
somesthetic, vestibular, visual, and auditory sensory systems, as
well as from motor and nonmotor areas of the cerebral cortex.
Disorders of the Cerebellum and Its
Connections

7. Cerebellum seems to work as an ”internal
clock”, which comes into play during the
control of movement, as well as during
perceptual processing.

8. CEREBELLUM FUNCTIONS
• For many years, functions related only to movement, gait,
posture, and balance were attributed to the cerebellum.
• Cerebellum promotes the synchrony and accuracy of
movement required for purposeful motor activity.
• However, some studies have suggested a possible involvement
of the cerebellum in cognition, emotion processing and
behaviour.
Rev Bras Psiquiatr. 2008;30(3):281-9
Disorders of the Cerebellum and Its
Connections

9. SIGNS AND SYMPTOMS OF
CEREBELLAR DAMAGE
• Loss of muscle tone
• Incoordination of volitional movement, with abnormalities in
the rate, range, and force of movement, so that there is
irregular acceleration and deceleration of the movement
resulting in an intention tremor
• Minor muscle weakness, fatigability, and impairment of
associated movements problems maintaining equilibrium.
Psychiatry (Edgemont) 2010;7(9):38–43

10. BALANCE
• Lesions that involve the superior cerebellar peduncle, which
ascends to the thalamus, or the dentate nucleus, which
indirectly projects to the premotor cortex, cause the most
severe and enduring cerebellar symptoms.
• However, lesions of the cerebellar vermis, which is in the
midline, cause more severe disturbances of equilibrium and
gait.

11. HYPOTONIA
• Hypotonia can be tested by tapping the wrists of the
outstretched arms.
• The affected limb will be displaced through a wider range than
normal, due to the hypotonic muscles reduced ability to fixate
the arms.
• Pendularity in the knee-jerk reflex due to defective tonic
contraction of the quadriceps

12. CEREBELLUM AND PSYCHIATRIC
DISORDERS
• Although the cerebellum has an important role in gait and motor
function, the importance of the cerebellum to psychiatric disorders
has recently been the subject of focus and debate.
• There is increasing evidence that the cerebellum is not only
connected with motor pathways but also with other cortical and
association areas involved in superior mental functions, suggesting
the involvement of the cerebellum in cognition in the
pathophysiology of psychiatric disorders.
Rev Bras Psiquiatr. 2008;30(3):281-9

13. AUTISM SPECTRUM DISORDERS
• Autism is associated with repetitive and stereotypic movement, impaired
communication, and profound difficulties with social reciprocity.
• Patients with autism have been found to have a reduction of Purkinje cell
density in the cerebellar cortex.
• Patients with autism also have cytoplasmic inclusions in their Purkinje cells,
a reduction in the number of cells, and ectopic grey matter in the deep
cerebellar nuclei, as well as an intense neuroinflammatory process
extending to the cerebellar white matter.
Psychiatry (Edgemont) 2010;7(9):38–43

14. SCHIZOPHRENIA
• Alteration in cortico-cerebellar activity
• Cerebellar atrophy
• Patients with schizophrenia have decreased blood flow in the
cerebellum leads to diverse functional systems of the brain, including
memory, attention, social cognition, and emotion.
• Soft neurological signs suggestive of cerebellar dysfunction, such as
subtle ataxia, difficulties in coordination, dysdiadochokinesia,
intentional tremor, dysmetria of the ocular saccadic movements are
frequent in patients with schizophrenia
Rev Bras Psiquiatr. 2008;30(3):281-9

15. SCHIZOPHRENIA
• Additionally, emergence of positive symptomatology
(especially delusions), as well as cognitive deficits and negative
symptomatology, including flattened affect, thought disorder,
avolition, social isolation, and poor speech, have frequently
been reported in individuals with cerebellar lesions.
• Thus Converging evidence from neuroimaging and cognitive
studies suggests cerebellar abnormalities in schizophrenia,
leads to some of the positive, negative, and cognitive
symptoms present in this disease.
Rev Bras Psiquiatr. 2008;30(3):281-9

16. BIPOLAR DISORDER
• Cerebellar atrophy & reduction in blood flow
• Yates et al. found a greater rate of cerebellar atrophy in
patients with bipolar disorder who were over 50 years old, but
not in younger bipolar patients compared with healthy
volunteers.
• Alcohol abuse may contribute to abnormal cerebellar anatomy
in bipolar patients
• posterior-inferior cerebellar vermal abnormalities are present
in patients with multiple-episode bipolar disorder
Rev Bras Psiquiatr. 2008;30(3):281-9

17. DEPRESSION
• Cerebellar atrophy
• Cognitive deficits in depressed patients were related to lower
cerebellar cortex activity.
• Impairment in emotion expression might be, part, due to a
disruption in the functional connection between the
cerebellum and frontal lobe.
Rev Bras Psiquiatr. 2008;30(3):281-9

18. ANXIETY DISORDERS
• Cerebellum might play a role in anxiety manifestations like
posttraumatic stress disorder (PTSD) and generalized anxiety
disorder (GAD).
• The cerebellum seems to be reduced in its volume but more
activated in some tasks in patients with anxiety disorders.
Rev Bras Psiquiatr. 2008;30(3):281-9

19. NEURODEGENERATIVE
DISORDERS
• Cerebellar volume seems to be reduced in patients with dementia.
• In Alzheimer’s disease (AD), cerebral structures interconnected with
cerebellum are affected by neurofibrillary tangles and neuronal loss
in later stages of the disease. Additionally, although cerebellum is
virtually free of neurofibrillary pathology, the magnitude of
cerebellar atrophy strongly correlates with duration and stage of
illness.
• In most of the of studies, cerebellum atrophy is evident only in late
stages of disease
Rev Bras Psiquiatr. 2008;30(3):281-9

20. CEREBELLAR-COGNITIVE AFFECTIVE
SYNDROME (CCAS)