Tremor-mediating thalamic zone studied in humans and in monkeys

Area of Science:

• Neuroscience
• Neurology
• Movement Disorders

Background:

• Tremor is a common neurological symptom characterized by involuntary rhythmic oscillations.
• The precise brain circuitry underlying tremor generation remains incompletely understood.
• Previous research has implicated the thalamus in motor control and tremor pathophysiology.

Purpose of the Study:

• To pinpoint the specific thalamic nucleus and its subregion involved in mediating rhythmic burst activity associated with tremor.
• To investigate similarities in tremor-related neural activity between human clinical cases and animal models.

Main Methods:

• Microelectrode recordings were utilized in both human patients experiencing tremor and in monkeys with experimentally induced tremor.
• The study focused on identifying rhythmic burst activity time-locked with the tremor.
• Localization of the active neuronal populations within specific thalamic nuclei was performed.

Main Results:

• A restricted area within the ventrointermedius nucleus (Vim) in humans exhibited rhythmic burst activity correlated with tremor.
• In monkeys, the VPLo nucleus showed similar tremor-related rhythmic burst activity.
• In both species, the involvement was confined to the lateral and ventrocaudal portions of these nuclei, termed the kinesthetic zone.

Conclusions:

• The kinesthetic zone of the thalamus, specifically the Vim in humans and VPLo in monkeys, plays a crucial role in generating tremor-related rhythmic activity.
• These findings suggest a conserved neural substrate for tremor across species.
• A potential neural circuit mediating tremor is proposed based on these results.