Recording Cortical and Subcortical Neuronal Activity Using Electrode Systems

Begin with a human participant with DBS electrodes implanted deep within the brain's neuron-rich subcortical region.

Mark the positions on the scalp for the EEG electrode placement.

Clean the marked positions with a disinfectant and apply a conductive paste for electrode contact.

Attach the EEG electrodes to the scalp markings to monitor cortical neurons.

Connect the DBS electrodes and the EEG electrodes to an EEG control box for signal amplification and recording.

Perform a visual test where the participant focuses on a pattern of arrows.

A change in the pattern is detected by the eyes, providing visual stimulation to the brain.

This stimulus activates the neurons in both cortical and subcortical regions, generating electrical signals.

The DBS electrode records the neuronal electrical activity from the subcortical neurons, while the EEG electrode records neuronal activity from the cortical region.

Begin by setting up the electroencephalography or EEG equipment in the testing room. Connect the recording computer to the EEG system, and start the EEG recording software. Click File and then New Workspace to define the workspace in the EEG recording software by specifying a sampling frequency of 5 kilohertz, a low cutoff and high cutoff frequency EEG channels according to the International 10-20 system, and local field potential or LFP channels. Click Monitor to verify that the specified channels are now set up for recording.

Next, set up the stimulus computer, and check the connection to the parallel port of the EEG system. Start the Stimulus software. Click Run to check the paradigm's functionality on the computer monitor.

Ensure triggers from the stimulus computer are sent to the recording system by checking their appearance on the EEG recording software during presentation of stimuli as well as during the subject's response. Mark the vertex of the patient's head as the midpoint between the nasion and inion by using a skin marker pen. Then, mark the chosen EEG electrode positions according to the 10-20 system.

Clean each selected location with an isopropyl alcohol pad and abrasive paste. Then, attach the EEG surface electrodes to the scalp. Connect the percutaneous extension cable from deep brain stimulation or DBS electrodes to an external cable connector. Connect each electrode provided by the external cable connector to the EEG control box according to the EEG recording setup. Connect the EEG scalp electrodes to the EEG control box.

Next, provide the patient with instructions about the flanker task. Ensure that the patient is comfortable, and instruct him to stop the experiment at any time for discomfort. Click Run on the stimulus software so that the patient is able to see the paradigm on the monitor. Perform a training session with the patient until they are comfortable with the task. Finally, start simultaneous recording of subcortical LFP and cortical EEG brain activity while the patient performs the flanker task.