Long Trace Eyeblink Conditioning Is Largely Preserved in Essential Tremor

Area of Science:

• Neuroscience
• Clinical Neurology
• Cognitive Psychology

Background:

• Essential tremor (ET) is a neurological disorder impacting motor control.
• The cerebellum and prefrontal cortex (PFC) are implicated in ET pathophysiology.
• Trace eyeblink conditioning, particularly with long interstimulus intervals, requires intact hippocampus, PFC, and cerebellar function.

Purpose of the Study:

• To investigate whether long trace eyeblink conditioning is impaired in patients with essential tremor.
• To assess the role of the prefrontal cortex and cerebellum in essential tremor using a cognitive task.

Main Methods:

• A long trace conditioning paradigm was employed with 18 ET patients and 18 controls.
• Participants underwent 100 paired conditioned-unconditioned response trials followed by 30 extinction trials.
• Clinical scales assessed tremor severity and the presence of cerebellar signs.

Main Results:

• Essential tremor patients did not exhibit significant impairment in acquiring conditioned eyeblink responses compared to controls (23.3% vs. 24.1%).
• A subgroup of ET patients with cerebellar signs showed numerically lower, though not statistically significant, conditioning (16.4%) versus those without (26.8%).
• These findings suggest that the PFC areas involved in long trace eyeblink conditioning are largely unaffected in ET.

Conclusions:

• Long trace eyeblink conditioning is not impaired in essential tremor patients.
• While not statistically significant, reduced conditioning was observed in ET patients with clinical cerebellar signs.
• The prefrontal cortex's role in this specific conditioning paradigm appears preserved in essential tremor.