Combined Invasive Subcortical and Non-invasive Surface Neurophysiological Recordings for the Assessment of Cognitive and Emotional Functions in Humans

Summary

The present protocol aims at assessing cognitive-emotional functions in the basal ganglia by simultaneous neurophysiological recording of local field potentials and non-invasive brain cortical activity (EEG). The procedure is exemplified by the use of paradigms involving speech stimuli with emotional connotation or the Flanker task involving cognitive control.

Abstract

In spite of the success in applying non-invasive electroencephalography (EEG), magneto-encephalography (MEG) and functional magnetic resonance imaging (fMRI) for extracting crucial information about the mechanism of the human brain, such methods remain insufficient to provide information about physiological processes reflecting cognitive and emotional functions at the subcortical level. In this respect, modern invasive clinical approaches in humans, such as deep brain stimulation (DBS), offer a tremendous possibility to record subcortical brain activity, namely local field potentials (LFPs) representing coherent activity of neural assemblies from localized basal ganglia or thalamic regions. Notwithstanding the fact that invasive approaches in humans are applied only after medical indication and thus recorded data correspond to altered brain circuits, valuable insight can be gained regarding the presence of intact brain functions in relation to brain oscillatory activity and the pathophysiology of disorders in response to experimental cognitive paradigms. In this direction, a growing number of DBS studies in patients with Parkinson's disease (PD) target not only motor functions but also higher level processes such as emotions, decision-making, attention, memory and sensory perception. Recent clinical trials also emphasize the role of DBS as an alternative treatment in neuropsychiatric disorders ranging from obsessive compulsive disorder (OCD) to chronic disorders of consciousness (DOC). Consequently, we focus on the use of combined invasive (LFP) and non-invasive (EEG) human brain recordings in assessing the role of cortical-subcortical structures in cognitive and emotional processing trough experimental paradigms (e.g. speech stimuli with emotional connotation or paradigms of cognitive control such as the Flanker task), for patients undergoing DBS treatment.

Introduction

Invasive neurophysiological recordings in humans date back to seminal studies targeting electrocorticographic recordings from cortical areas and the cerebellum during epilepsy surgery and tumor research¹. A critical milestone into further development of such recording procedure has been the introduction of the stereotactic technique that provides safe and efficient access to deep structures of the human brain². Apart from clinical treatment, brain invasive approaches in humans provide a rather unique opportunity to study brain function in relation to recorded activity patterns modulated by external stimuli, notably the case of intra- and post-ope....

Protocol

The DBS procedure and invasive recordings were approved by the Ethics Commission of the University Clinic Düsseldorf, Germany.

1. Experimental Paradigm Design and Patient's Consent

NOTE: Design an experimental paradigm or select an existing experimental paradigm to target a cognitive/emotional aspect of interest.

1. Select patients that will undergo DBS-treatment. Ask if the DBS-Patient meets the study's inclusion criteria. If yes, obtain signed informed consent from patient and/or ethical commission (if applicable) to carry out a post-operative recording and application of the respective cognitive parad....

Results

For the DBS-DOC case (Example 2), we now provide data on target localization for DBS implantation, schematic diagrams of LFP electrode and EEG set up, exemplary recordings of EEG and LFP activity (raw data) and representative analysis results:

Figure 2A shows planned trajectory (black line) projected on an anatomic atlas³⁶, section 30, coronary, 10.7 mm behind the anterior commissure (AC) (red line: A.......

Discussion

In contrast to non-invasive brain recording techniques like scalp-EEG and MEG, the proposed combined invasive and non-invasive neurophysiological recording framework provides a remarkable opportunity to extract information from cortical and subcortical areas in relation to cognitive-emotional tasks. Such information is reflected by brain oscillatory activity at multiple frequency bands and different levels of organization in relation to brain functioning⁴⁴. Brain oscillatory patterns that are relevant in our r.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
BrainAmp Amplifier	Brain Products GmbH, Gilching Germany		Quantity: 2
BrainVision Recorder Software	Brain Products GmbH, Gilching Germany		1 License
BrainVision Analyzer Software	Brain Products GmbH, Gilching Germany		1 License
Fiber Optic cables and USB connectors	Brain Products GmbH, Gilching Germany		These come with the above listed equipment
Electrode Input box (64 channels)	Brain Products GmbH, Gilching Germany		Quantity: 1
EEG gel	Natus Inc		Quantity: 1
Isopropyl alcohol	Schülke & Mayr GmbH, Germany		Quantity: 1
Skin preparation gel	Weaver and Co, USA		Quantity: 1
MATLAB	Math-Works, Natick, Massachusetts, USA		1 License
FieldTrip toolbox	http://www.fieldtriptoolbox.org/		Open Source
Macroelectrodes (model 3387 quadripolar DBS lead)	Medtronic Inc., Minneapolis, MN, USA		Quantity: 2
Sterile percutaneous extension wires (model 3550-05)	Medtronic Inc., Minneapolis, MN, USA		Quantity: 2
Twist lock cable (model 3550-03)	Medtronic Inc., Minneapolis, MN, USA		Quantity: 2
custom made connectors to DIN 428092 touch proof connectors			Quantity: 2
Vercise Lead kit DB -2201	Boston Scientific		Quantity: 2
Contact extension kit NM-3138	Boston Scientific		Quantity: 2
O.R. cabel & extension SC-4100 A	Boston Scientific		Quantity: 2
connector to touch proof	Twente Medical Systems International B.V.		Quantity: 2
CT scanner Modell PQ2000 (Postoperative CT scans)	Philips Healthcare GmbH Hamburg		Quantity: 1
Presentation Software (Flanker Task)	Neurobehavioral systems Inc.		1 License
MEG System	Elekta Neuromag Inc		Alternatively
High-density EEG sensor net (128 or 256 channels)	Electrical Geodesics Inc (EGI), USA		Alternatively