Non-invasive Deep Brain Stimulation to Improve Spatial Navigation Abilities in Individuals Following Traumatic Brain Injury

Investigation of the Plasticity of Deep Brain Structures in Mild Cognitive Impairment and Healthy Aging (PlasMA)

Impairments in spatial memory and spatial navigation are commonly reported amongst patients presenting post-traumatic brain injury (TBI). In this study, the investigators examine the effect of non-invasive deep brain stimulation of the hippocampal-entorhinal complex (HC-EC), a key region supporting navigation abilities, on spatial navigation performance in TBI patients. Using a virtual reality task where participants must first encode and later recall the location of objects in a virtual arena, the investigators contrast performance while active versus control stimulation is applied to the HC-EC. The investigators additionally record brain activity using electroencephalography (EEG) prior to, during, and after task performance to characterize the neural correlates of spatial navigation abilities in TBI patients, and how they are affected by stimulation.

Patients will perform a virtual reality spatial navigation task comparable to that used previously by Beanato and colleagues (2024; DOI: 10.1126/sciadv.ado4103). Patients will perform 4 blocks of task, each lasting approximately 10 minutes; during the full duration of each block, either active or control transcranial temporal interference stimulation (tTIS) will be applied in an interleaved manner, and EEG recordings will be collected. Resting-state EEG recordings will also be collected prior to and following task performance.

Structural, diffusion-weighted, and resting-state MRI scans will additionally be performed during a prior baseline session.

Inclusion Criteria:

• Age ≥ 18 years
• Clinical diagnosis of TBI
• No history of other severe neurological or psychiatric disorders

Exclusion Criteria:

• Unable to consent

• Severe neuropsychiatric (e.g., major depression, severe dementia) or unstable systemic diseases (e.g., severe progressive and unstable cancer, life threatening infectious diseases)

• Severe sensory or cognitive impairment or musculoskeletal dysfunctions prohibiting to understand instructions or to perform the experimental tasks

• Inability to follow or non-compliance with the procedures of the study

• Contraindications for NIBS or MRI:

  • Electronic or ferromagnetic medical implants/device, non-MRI compatible metal implant
  • History of seizures
  • Medication that significantly interacts with NIBS being benzodiazepines, tricyclic antidepressants and antipsychotics

• Regular use of narcotic drugs

• Pregnancy

• Request of not being informed in case of incidental findings

• Concomitant participation in another trial involving probing of neuronal plasticity