Related Experiment Video
Updated: May 24, 2026
14:27
Investigating Long-term Synaptic Plasticity in Interlamellar Hippocampus CA1 by Electrophysiological Field Recording
Published on: August 11, 2019
Hippocampal volume and memory in narcoleptics with cataplexy
Eun Yeon Joo1, Sun Hwa Kim, Sung-Tae Kim
1Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Sleep Medicine
|February 25, 2012
Summary
Narcoleptics exhibit reduced hippocampal volume (HV) compared to controls, linked to sleep patterns but not memory deficits. This suggests anatomical changes in narcolepsy severity.
Area of Science:
- Neuroscience
- Neurology
- Sleep Medicine
Background:
- Narcolepsy is a chronic neurological disorder affecting sleep-wake regulation.
- The role of structural brain changes, specifically hippocampal volume (HV), in narcolepsy is not fully understood.
Purpose of the Study:
- To compare hippocampal volume (HV) between individuals with narcolepsy and healthy controls.
- To investigate the association between HV and memory function in narcoleptics.
Main Methods:
- Magnetic resonance imaging (MRI) was used to manually measure left and right hippocampal volumes (HV) and intracranial volumes (ICV).
- 36 drug-naïve narcoleptics with cataplexy and 36 matched controls underwent MRI scans.
- Verbal and visual memory were assessed using the Korean California Verbal Learning Test and Rey Complex Figure Test.
Main Results:
- Narcoleptics had significantly smaller bilateral hippocampal volumes (HV) compared to controls, even after adjusting for age, sex, and ICV.
- No significant differences in absolute memory scores were found between narcoleptics and controls.
- In narcoleptics, HV showed a positive correlation with mean sleep and REM sleep latencies.
Conclusions:
- Individuals with narcolepsy demonstrate reduced bilateral hippocampal volumes.
- Hippocampal volume (HV) is significantly related to sleep and REM sleep latencies in narcoleptics.
- Findings support the presence of functional and anatomical deficits in medial temporal areas associated with narcolepsy severity.
Related Concept Videos
01:07Narcolepsy
Narcolepsy is a chronic sleep disorder characterized by pervasive, uncontrolled sleepiness and other sleep disturbances. One of its hallmark symptoms is an abrupt transition to REM sleep upon falling asleep, which causes symptoms typically associated with this phase to occur unexpectedly during wakefulness. These include the following symptoms, which typically last from a minute or two to half an hour.
01:19Role of Hippocampus in Memory
The hippocampus, a critical brain structure, plays an essential role in memory processing, particularly in the formation and retrieval of memory. This small, seahorse-shaped region is located within the medial temporal lobe, with one hippocampus in each brain hemisphere. Experimental studies involving lesions in the hippocampi of rats have demonstrated significant impairments in tasks such as object recognition and maze navigation, indicating the hippocampus involvement in both recognition and...
01:24Sleep-Wake Cycles
Sleep is an essential physiological process vital to maintaining overall well-being. The reticular activating system (RAS), a network of neurons in the brainstem, regulates wakefulness and sleep. While it may seem passive, sleep consists of distinct cycles, each with its unique characteristics and functions. Two key sleep phases are non-rapid eye movement (NREM) and rapid eye movement (REM).
NREM Sleep
NREM sleep comprises four progressive stages that seamlessly merge:
NREM Sleep
NREM sleep comprises four progressive stages that seamlessly merge: