Related Experiment Video
Updated: Jan 15, 2026
10:37
Transcranial Direct Current Stimulation tDCS for Memory Enhancement
Published on: September 18, 2021
15.5K
Effect of fornix stimulation on acute memory encoding
Anna R Kimata1,2,3, Matthew Chan1, Bryan Zheng2,3
1Department of Neuroscience and The Carney Institute, Brown University, Providence, Rhode Island, United States.
Journal of Neurophysiology
|October 13, 2025
Summary
Deep brain stimulation (DBS) of the fornix in early Alzheimer's disease patients impaired acute memory encoding. Higher stimulation frequencies worsened memory performance, suggesting fornix stimulation directly impacts memory formation.
Area of Science:
- Neuroscience
- Cognitive Science
- Neurology
Background:
- Electrical stimulation of the Circuit of Papez for memory enhancement has yielded inconsistent results.
- The precise effects of fornix stimulation on memory encoding remain unclear, with potential variability due to stimulation protocols.
Purpose of the Study:
- To investigate the acute effects of fornix deep brain stimulation (DBS) on memory function in early Alzheimer's disease.
- To determine if stimulation protocols influence memory outcomes and if effects are specific to memory encoding.
Main Methods:
- Conducted memory experiments during awake DBS surgery and postoperatively in 5 patients with early Alzheimer's disease.
- Utilized a parametric episodic memory task with distinct encoding, attention, and delayed recall phases.
- Tested various stimulation frequencies and protocols to assess impact on memory performance.
Main Results:
- Fornix stimulation generally impaired memory performance across both intraoperative and postoperative settings.
- Higher stimulation frequencies were associated with greater detriments in memory recall.
- Stimulation specifically affected trial-by-trial memory encoding, not attention or working memory.
Conclusions:
- Open-loop fornix stimulation directly impairs acute, item-specific memory encoding in individuals with early Alzheimer's disease.
- The findings suggest that fornix stimulation, particularly at higher frequencies, negatively impacts memory formation.
- Further research is needed to determine the chronic effects of fornix stimulation on memory and cognition.
Related Concept Videos
01:23Role of Neurotransmitters in Memory
2.5K
Neurotransmitters are integral to the brain's communication system, enabling neurons to transmit signals across synapses. This chemical exchange underpins various cognitive functions, including memory processes. The role of neurotransmitters in memory is multifaceted, influencing the encoding, consolidation, and retrieval of memories through their action on different neural circuits.
Glutamate and Synaptic Plasticity
Glutamate, the brain's main excitatory neurotransmitter, is...
Glutamate and Synaptic Plasticity
Glutamate, the brain's main excitatory neurotransmitter, is...
2.5K
01:25Long-term Potentiation
3.4K
Long-term potentiation, or LTP, is one of the ways by which synaptic plasticity—changes in the strength of chemical synapses—can occur in the brain. LTP is the process of synaptic strengthening that occurs over time between pre and postsynaptic neuronal connections. The synaptic strengthening of LTP works in opposition to the synaptic weakening of long-term depression (LTD) and together are the main mechanisms that underlie learning and memory.
Hebbian LTP
LTP can occur when...
Hebbian LTP
LTP can occur when...
3.4K
01:35Long-term Potentiation
58.3K
Long-term potentiation, or LTP, is one of the ways by which synaptic plasticity—changes in the strength of chemical synapses—can occur in the brain. LTP is the process of synaptic strengthening that occurs over time between pre- and postsynaptic neuronal connections. The synaptic strengthening of LTP works in opposition to the synaptic weakening of long-term depression (LTD) and together are the main mechanisms that underlie learning and memory.
58.3K
01:14Role of Cerebellum and Prefrontal Cortex in Memory
1.0K
The cerebellum, while traditionally associated with motor control, also plays a crucial role in memory, particularly in procedural memory, which involves learning motor tasks that become automatic through repetition. For example, studies have shown that when the cerebellum is damaged, individuals or animals lose the ability to learn conditioned motor responses, such as the conditioned eye-blink response in classical conditioning experiments with rabbits. This study demonstrates the...
1.0K
01:18Long-Term Memory
648
Long-term memory is a relatively permanent type of memory, capable of storing vast amounts of information over extended periods. Its storage capacity is generally considered unlimited.
Long-term memory can be categorized into two primary types: explicit and implicit memory. Explicit memory, also known as declarative memory, involves the conscious recollection of information that we deliberately try to remember, recall, and articulate. This type of memory encompasses specific facts, events, and...
Long-term memory can be categorized into two primary types: explicit and implicit memory. Explicit memory, also known as declarative memory, involves the conscious recollection of information that we deliberately try to remember, recall, and articulate. This type of memory encompasses specific facts, events, and...
648
01:26Higher Mental Functions of Brain: Learning and Memory
1.9K
Memory is one of the most vital higher mental functions of the brain. Memory is closely related to learning because it enables us to retain information and experiences from our past to use them in our present life. It also helps us to remember facts, events, and skills, such as riding a bike or swimming. There are two types of memory — declarative memory, which involves memorizing facts or events, and procedural memory, which enables us to remember how to do something like writing or...
1.9K