The hyperexcitable brain: two papers published

Jason Braithwaite

New evidence for brain hyperexcitability underlying hallucinations in non-clinical samples 

A new paper from Dr Jason Braithwaite and colleagues from the School of Psychology, has been published in the top international journal 'Cortex'.

This study, the first of its kind, reported findings from a trans-cranial direct current stimulation (tDCS) protocol applied to the visual cortex of individuals predisposed to anomalous / hallucinatory experiences.

It was found that the brains of those predisposed to hallucinatory experiences responded more strongly to excitatory tDCS stimulation of the visual cortex, and less well to inhibitory tDCS stimulation of the visual cortex (relative to a control group).

Both findings are consistent with the idea that those individuals predisposed to anomalous hallucinatory experiences have a cortex that is indeed hyperexcitable.  This latent hyperexcitability is one factor that underlies the predisposition to spontaneous anomalous perceptions - even in non-clinical or neurological groups.

This research was funded by the Leverhulme Trust [RPG-2012-500] with contributions from the Bial Foundation [#21/12].

Reference:

Braithwaite, J.J., Mevorach, C., & Takahashi, C (2015). Stimulating the aberrant brain: Evidence for increased cortical hyperexcitability from a transcranial Direct Current Stimulation (tDCS) study of individuals predisposed to anomalous perceptions. Cortex, 69, doi:10.1016/j.cortex.2015.03.023. 

 

New measure of brain hyperexcitability

A new study from a collaboration between midlands universities (Birmingham / Warwick) led by Dr Jason Braithwaite, has been published in the interdisciplinary journal 'Cognitive Neuropsychiatry'.

This research has developed the first verified proxy measure for cortical hyperexcitability - termed the "Cortical Hyperexcitability index (CHi)".  The study was based on 250 participants and used the latest techniques in Exploratory Factor Analysis and Parallel Analysis to develop the measure.

These procedures revealed three separate factors as the most parsimonious solution underlying the concept of cortical hyperexcitability.  The 3 factors were defined as;

  1. heightened visual sensitivity and discomfort
  2. negative aura-type visual aberrations
  3. positive aura-type visual aberrations

The identification of three factors suggests that multiple mechanisms underlie the notion of cortical hyperexcitability, providing researchers with new and greater precision in delineating these underlying features.

The three-factor structure of the CHi, and the increased precision could aid the interpretation of findings from neuroscientific (i.e., brain-imaging / stimulation) examinations of cortical processes underlying aberrant perceptions across a host of clinical, neurological, and pathological conditions.  As a consequence, the CHi is a useful and comprehensive proxy measure of cortical hyperexcitability with considerable scientific and clinical utility.

This research was funded by the Leverhulme Trust [RPG-2012-500] with contributions from the Bial Foundation [#21/12].    

Reference:

Braithwaite, J.J., Marchant, R., Takahashi, C., Dewe, H., & Watson, D (2015).  The Cortical Hyperexcitability Index (CHi): A new measure for quantifying correlates of visually driven cortical hyperexcitability.  Cognitive Neuropsychiatry (20), 4, 330-348. doi:10.1080/13546805.2015.1040152.