Temporal Interference Stimulation Can Enhance or Disrupt Human Memory Encoding as a Function of Brain Location and...

Area of Science:

• Neuroscience
• Cognitive Science
• Neuromodulation

Background:

• Visual memory involves synchronized activity between medial temporal lobes and neocortical regions.
• Non-invasive neuromodulation struggles to precisely target deeper brain structures like the temporal lobes without stimulating the cortex.

Purpose of the Study:

• To investigate the impact of Temporal Interference (TI) stimulation on figure memory encoding.
• To explore the effects of TI on combinations of medial temporal lobe and neocortical brain regions.
• To determine the role of frequency and focality in non-invasive brain stimulation for memory.

Main Methods:

• Utilized Temporal Interference (TI) stimulation, a novel non-invasive technique using high-frequency carrier fields.
• Applied TI with varying frequency envelopes (130 Hz and 5 Hz offsets) to bilateral hippocampi and temporal cortices in 70 healthy participants.
• Assessed memory encoding using the Rey-Osterrieth and Taylor Complex Figure tasks, complemented by functional MRI.

Main Results:

• Higher frequency TI (130 Hz offset) targeting hippocampi and temporal cortices significantly impaired recall (p = 6.54e-04).
• Lower frequency TI (5 Hz offset) targeting only hippocampi significantly enhanced recall (p = 0.0447).
• Functional MRI showed distinct hippocampal BOLD signals, connectivity, and network differences between 130 Hz and 5 Hz TI.

Conclusions:

• TI stimulation can bidirectionally modulate memory encoding through precise frequency and target selection.
• Demonstrates the critical role of frequency and focality in non-invasive brain stimulation for cognitive functions.
• Highlights TI as a promising tool for cognitive neuroscience research and potential therapeutic interventions for memory disorders.