Biology subjects

Missey, F.

Publications and source records attributed to Missey, F..

4 recordsLinked to original sources

bioRxiv2025

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

Visual memory relies on synchronized interactions and rhythms between the medial temporal lobes and neocortical brain regions. Non-invasive manipulation of memory-related brain regions, specifically deeper temporal lobe regions, has been limited by the lack of precision of non-invasive neuromodulation - when targeting deeper structures, the cortex is always stimulated, never deeper structures in isolation. Temporal Interference (TI) stimulation, a novel non-invasive technique, uses high-frequency carrier fields to deliver targeted, physiologically relevant neuromodulation via amplitude-modulated envelopes at specific brain regions. Here, we investigate TIs impact on figure memory encoding in 70 healthy participants using the Rey-Osterrieth and Taylor Complex Figure tasks, with TI applied in several brain regions independently and simultaneously - allowing investigation of combinations of medial temporal lobe and neocortical brain regions. Interestingly, higher frequency TI envelopes (130 Hz offset) targeting bilateral hippocampi and temporal cortices significantly impair recall (p = 6.54e-04), while lower frequency TI envelopes (5 Hz offset) targeting only the bilateral hippocampi significantly enhance recall (p = 0.0447). Stimulation using other combinations of medial temporal lobe and neocortical regions showed no effect, underscoring the critical role of frequency and focality of non-invasive brain stimulation and correct target selection. Finally, functional MRI reveals strong differences between the effects of 130 Hz and 5 Hz envelopes, specifically in hippocampal BOLD signals, brain connectivity, default mode, and attentional networks. These findings demonstrate TIs ability to bidirectionally modulate memory encoding through precise frequency and target tuning, offering a powerful tool for cognitive neuroscience and potential therapeutic applications for memory disorders. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/677714v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@8e9db3org.highwire.dtl.DTLVardef@1135a3corg.highwire.dtl.DTLVardef@189345dorg.highwire.dtl.DTLVardef@ccca8f_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract:C_FLOATNO Temporal Interference stimulation for bidirectional memory modulation assessed via behavioral testing and MRI scanning. C_FIG

neuroscience↗

bioRxiv2023

Multipair phase-modulated temporal interference electrical stimulation combined with fMRI.

Temporal Interference stimulation (TIS) is a promising non-invasive brain stimulation technique exploiting frequency-shifted kHz fields to modulate oscillatory neural activity without invasive procedures. While human studies suggest TIS efficacy in targeting relatively deep brain structures, recent computational modeling and animal studies indicate potential off-target stimulations via the application of standard TIS protocols. Here, we computationally optimized TIS targeting for the prefrontal cortex (PFC) in mice. Combining in vivo electrophysiological recordings, intracellular calcium dynamics with fiber photometry, and functional MRI, we confirmed TIS-induced amplitude modulation, neuronal entrainment and hemodynamic responses in the PFC, while also identifying off-target modulations. To mitigate off-target effects, we propose a novel configuration with three electrode pairs, one of which is actively phase-shifted by 180 degrees. This cancelling field significantly enhanced TIS focality, reducing off-target effects without compromising the TIS efficacy in the target area. This work effectively addresses one of TIS most critical shortcomings and opens new avenues for research and clinical applications. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=178 SRC="FIGDIR/small/571679v2_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@b04067org.highwire.dtl.DTLVardef@154549aorg.highwire.dtl.DTLVardef@17e63c3org.highwire.dtl.DTLVardef@c7a341_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2022

Focal Non-invasive Deep-brain Stimulation with Temporal Interference for the Suppression of Epileptic Biomarkers

Neurostimulation applied from deep brain stimulation (DBS) electrodes is an effective therapeutic intervention in patients suffering from intractable drug-resistant epilepsy when resective surgery is contraindicated or failed. Inhibitory DBS to suppress seizures and associated epileptogenic biomarkers could be performed with high-frequency stimulation (HFS), typically between 100 -165Hz, to various deep-seated targets such as for instance the Mesio-temporal lobe (MTL) which leads to changes in brain rhythms, specifically in the hippocampus. The most prominent alterations concern high-frequency oscillations (HFOs), namely increase in ripples, a reduction in pathological Fast Ripples (FRs), and a decrease in pathological interictal epileptiform discharges (IEDs). In the current study, we use Temporal Interference stimulation to provide a non-invasive focal DBS (130 Hz) of the MTL, specifically the hippocampus, which increases physiological ripples, and decreases the number of FRs and IEDs in a mouse model of epilepsy. Similarly, we show the inability of 130 Hz transcranial current stimulation (TCS) to achieve similar results. The method could potentially revolutionize how DBS, certainly in epilepsy, is performed, and we therefore further demonstrate the translatability to human subjects via measurements of the TI stimulation vs TCS in human cadavers. Results show the better penetration of TI fields into the human hippocampus as compared with TCS. Finally, we provide evidence of the efficacy of the specific form of Pulse-width Modulated TI (PWM-TI), implemented with square waves, which is used in this study. One Sentence SummaryA non-invasive deep brain stimulation applied via temporal interference achieves the suppression of biomarkers of epilepsy in mice and is scaled to humans.

neuroscience↗

bioRxiv2020

Orientation of Temporal Interference for Non-Invasive Deep Brain Stimulation in Epilepsy

In patients with focal drug-resistant epilepsy, electrical stimulation from intracranial electrodes is frequently used for the localization of seizure onset zones and related pathological networks. The ability of electrically stimulated tissue to generate beta and gamma range oscillations, called rapid-discharges, is a frequent indication of an epileptogenic zone. However, a limit of intracranial stimulation is the fixed physical location and number of implanted electrodes, leaving numerous clinically and functionally relevant brain regions unexplored. Here, we demonstrate an alternative technique relying exclusively on nonpenetrating surface electrodes, namely an orientation-tunable form of temporally-interfering (TI) electric fields to target the CA3 of the mouse hippocampus which focally evokes seizure-like events (SLEs) having the characteristic frequencies of rapid-discharges, but without the necessity of the implanted electrodes. The orientation of the topical electrodes with respect to the orientation of the hippocampus is demonstrated to strongly control the threshold for evoking SLEs. Additionally, we demonstrate the use of square waves as an alternative to sine waves for TI stimulation. An orientation-dependent analysis of classic implanted electrodes to evoke SLEs in the hippocampus is subsequently utilized to support the results of the minimally-invasive temporally-interfering fields. The principles of orientation-tunable TI stimulation seen here can be generally applicable in a wide range of other excitable tissues and brain regions, overcoming several limitations of fixed electrodes which penetrate tissue.

neuroscience↗