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by Shaheen E Lakhan, MD, PhD, MEd, MS | February 8, 2016
National Geographic Channel will shortly air “Brain Games: Meet The Brain” (premiering Sunday, February 14 at 9 pm ET). As part of a virtual roundtable, Brain Blogger was selected to screen the episode and address the thought provoking question raised therein:
Do you think individuals can train their brain to respond in
a particular way to certain situations, or do you think
our brain’s innate “startle response” is too hardwired to alter?
I will address the roundtable question from a clinician’s standpoint. In short, yes we can “train” our brains to respond in very “particular” ways and yes our “startle response” is “hardwired.” The question was phrased to suggest that these two concepts are mutually exclusive, however, I will present an alternate reality in which both co-exist.
With the development of electroencephalography (EEG), we finally had a glimpse into the living brain without cracking it open. Using small electrodes over the scalp, we were able to detect the electrical activity of the brain without even breaking the skin. EEG still remains the golden standard for detecting epileptic seizure activity in neurology offices’ worldwide. And, from it’s advent, it has been used as the first modality in neurofeedback — a collection of techniques that train the brain and help improve its functions. It has most successfully been applied to ADHD, epilepsy, depression, anxiety, and Parkinson’s disease.
The technologies for neurofeedback expanded beyond EEG to other advanced modalities including functional magnetic resonance imaging (fMRI), functional near infrared spectroscopy (fNIRS), and magnetoencephalography (MEG). One just needs to read NeuroRegulation (formerly the Journal of Neurotherapy) for the plethora of clinical applications using neurofeedback.
With such mounting evidence that we can train our brains through EEG and other neurofeedback methods, we come back to the “startle response” — which is really a defensive reflex stemming from the brainstem aimed to protect the body from threats. It is best illustrated in infants in what is known as the Moro reflex. Watch this video of a baby’s normal response (the Moro reflex) to an unexpected touch:
As we age, this “primitive reflex” dampens and it takes a lot (like free falling in a roller coaster) to trigger it. It is only when problems arise in the brain do resemblants of the startle response return with great regularity. In the neurodegenerative disease Creutzfeldt–Jakob disease (CJD) responsible for a rapid onset of dementia, the startle response in heightened and may cause uncontrolled jerks of the body (myoclonus). The same can occur in juvenile myoclonic epilepsy — a very common form of epilepsy. Much rarer, the startle response may never go away in the case of hereditary hyperekplexia — a genetic neurological condition where patients experience a short period of rigidity and inability to move in response to threatening stimuli (e.g. loud noise).
After all, our brain’s have a finite number of processing units. So, when you touch, yell, or shine a bright light at someone, you are using up these limited projections in their brain. The threshold that “startles” someone is specific person-to-person and time-to-time — it depends on other things on the mind, our state of anxiousness, and the overall health of the brain (as we saw with epilepsy and dementia earlier). There is a great review article by Guirado and colleagues just published in Cerebral Cortex that outlines the research to date on how these signals compete for our attention.
In the end, we can train our minds to respond a certain way to stimuli and the startle response is hardwired, but, modulated by many biopsychosocial factors.
References
Kandemir M, Gündüz A, Uzun N, Yeni N, & K?z?ltan M (2015). Auditory startle response is normal in juvenile myoclonic epilepsy. Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology, 36 (7), 1247-9 PMID: 25805707
Guirado R, Umemori J, Sipilä P, & Castrén E (2016). Evidence for Competition for Target Innervation in the Medial Prefrontal Cortex. Cerebral cortex (New York, N.Y. : 1991), 26 (3), 1287-94 PMID: 26637448
Thibault RT, Lifshitz M, & Raz A (2016). The self-regulating brain and neurofeedback: Experimental science and clinical promise. Cortex; a journal devoted to the study of the nervous system and behavior, 74, 247-61 PMID: 26706052
Arns M, Heinrich H, & Strehl U (2014). Evaluation of neurofeedback in ADHD: the long and winding road. Biological psychology, 95, 108-15 PMID: 24321363
http://brainblogger.com/2016/02/08/training-the-brain-and-the-startle-response/
