Brain Changes in EEG and Brain Pulsatility to Novel Stimuli (Electro-PulCe)
Condition: Healthy Volunteers
Study type: Observational

Summary: 
      The oddball paradigm is one of the most widely used methods of brain exploration for the
      study of attentional processes. It allows the measurement, by means of an
      Electro-Enchephalogram (EEG), of evoked potentials reflecting the electrophysiological
      reactivity to the detection of novel stimuli within a stream of standard stimuli.

      Other studies have recently suggested that, in addition to neuronal activation, certain other
      physiological processes related to cerebrovascular reactivity, such as the Brain Tissue
      Pulsatility (BTP), could also be sensitive to various cognitive processes and in particular
      to attentional processes.

      In one of the latest studies published in collaboration with our group, it was shown that the
      amplitude of the electrophysiological response classically associated with attentional
      activity (P300 wave) was significantly correlated with the amplitude of BTP, suggesting the
      involvement of cerebrovascular processes in attentional functions. Nevertheless, in this
      study, the two methods of EEG and Tissue Pulsatility Imaging (TPI) were not synchronized,
      since TPI was performed at rest and not during the oddball task itself, and to date no study
      has sought to couple the methods of EEG and ultrasound TPI in an oddball paradigm, for a
      simultaneous characterization of neuronal and cerebrovascular responsiveness during
      attentional processes.

      The general objective of this study will be to evaluate changes in BTP during the detection
      of novel stimuli in an oddball task in healthy volunteers, in which the two methods of TPI
      and EEG will be coupled and synchronized.
    

Detailed description: 
      The oddball paradigm is one of the most widely used methods of brain exploration for the
      study of attentional processes. It allows the measurement, by means of an
      Electro-Enchephalogram (EEG), of evoked potentials reflecting the electrophysiological
      reactivity to the detection of novel stimuli within a stream of standard stimuli. Numerous
      studies have thus used the oddball paradigm to identify the neuronal reactivity involved in
      attentional orientation towards target stimuli.

      Other studies have recently suggested that, in addition to neuronal activation, certain other
      physiological processes related to cerebrovascular reactivity, such as the Brain Tissue
      Pulsatility (BTP), could also be sensitive to various cognitive processes and in particular
      to attentional processes. Ultrasound measurement of BTP is made possible by recent advances
      in both the development of ultrasound equipment and ultrasound signal processing. Our team
      and others have validated the measurement of BTP by ultrasound (Tissue Pulsatility Imaging -
      TPI) in healthy volunteers and clinical populations, and our results suggest that the
      mechanisms of BTP are significantly influenced by cerebrovascular physiology.

      In one of the latest studies published in collaboration with our group, it was shown that the
      amplitude of the electrophysiological response classically associated with attentional
      activity (P300 wave) was significantly correlated with the amplitude of BTP, suggesting the
      involvement of cerebrovascular processes in attentional functions. Nevertheless, in this
      study, the two methods of EEG and TPI were not synchronized, since TPI was performed at rest
      and not during the oddball task itself, and to date no study has sought to couple the methods
      of EEG and ultrasound TPI in an oddball paradigm, for a simultaneous characterization of
      neuronal and cerebrovascular responsiveness during attentional processes.

      The general objective of this study will be to evaluate changes in BTP during the detection
      of novel stimuli in an oddball task in healthy volunteers, in which the two methods of TPI
      and EEG will be coupled and synchronized.
    

Intervention name(s): Registration; Auditive oddball task
Intervention type(s): Other; Other
Intervention description(s): Synchronized recording of BTP in ultrasound, brain activity by EEG, heart rate and blood pressure.; Presentation of an auditory sequence, comprising 'Standard' (probability of occurrence: p = 0.90) and 'Deviants' (p = 0.10, targets) sounds via loudspeakers.
Observational model: Other
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Healthy volunteer
      
Keywords: Brain Tissue Pulsatility (BTP); Electroencephalogram (EEG); Auditive oddball task; Tissue Pulsatility Imaging (TPI)