Pathological laughter and crying: a link to the cerebellum

Area of Science:

• Neuroscience
• Neurology
• Psychiatry

Background:

• Pathological laughter and crying (PLC) is characterized by uncontrollable emotional outbursts.
• It is considered a disorder of emotional expression, distinct from mood disorders.
• The traditional view attributes PLC to disinhibition of a brainstem center due to cortical pathway damage.

Observation:

• A recent patient study and new neurobiological insights prompted a re-evaluation of PLC's origins.
• The study examined the neuroanatomical underpinnings of pathological emotional expression.

Findings:

• The study proposes that critical lesions in pathological laughter and crying occur in the cerebro-ponto-cerebellar pathways.
• This damage leads to cerebellar dysfunction in adjusting emotional expression to situational context.
• Consequently, emotional responses become inadequate or chaotic due to incomplete contextual information.

Implications:

• This finding challenges the traditional view of PLC etiology.
• It suggests a new neuroanatomical model for understanding and potentially treating pathological laughter and crying.
• Understanding these pathways is crucial for differentiating emotional expression disorders from mood disorders.