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Visual events have 100 m/s to hit brain target or go unnoticed

on 10 April 2020
The amazing brain

Imagine, you are having a great day, when, all of a sudden you have this overwhelming feeling of foreboding, your pulse starts racing, your chest is pounding and you say; for no reason, I became very anxious! Hmmm, the brain doesn't become anxious for no reason, so what is going on . . .

This research highlights what happens, or perhaps doesn't, when, a perceptual visual stimulus is not activated within 100 milliseconds (1/10th of a second) by a small area of the midbrain called the superior colliculus (SC). Superior relates to its position, not its authority, meaning above or at the top, as opposed to inferior, below, at the bottom. The midbrain (embryonic mesencephalon) is a relatively small part of the brain sitting atop of the brainstem, although, it plays a very significant role in how we function, physically, emotionally and psychologically! The major part of the visual pathway, the optic nerve/tract first passe through the optic chiasm, where part of it crosses over, decussates, right eye/left hemisphere (contralateral) etc. It is mostly the inner part of the visual field (towards the nose) that crosses over to the opposite hemisphere (contralateral). The outer part of the visual field (towards the temple) is processed by the same hemisphere (ipsilateral), right eye/right hemisphere etc. The part of the visual field that crosses over, travels through the pulvinar (part of the thalamus), which has connections to the amygdala and aspects of the extended amygdala. The part that stays within the same hemisphere, passes through the lateral geniculate nucleus, also part of the thalamus. But there is a secondary part of the ipsilateral (same side) visual field that passes through the superior colliculus and it is this part that the research below addresses.

As well as the circuitry mentioned in the research below. and detailed above, i.e. the pathways of the retina to the superior colliculus, there is the other circuit mentioned above, that between the visual field and the amygdala. It is useful to consider these structures and pathways, at least for those who suffer from an anxiety disorder because they go some way towards explaining how the brain responds to things it sees but of which, we have no awareness! Of course, it is not sufficient to just know about this circuitry, in order to help those who suffer from an anxiety disorder but it can be a useful part of the process towards finding a resolution for it! If we are oblivious to the workings of our brain, I believe we will more heavily rely upon hypothetical/philosophical structures, e.g. the subconscious mind!

An important part of this overall circuitry is the thalamus (part of the diencephalon), which is a division of the forebrain and sits between the midbrain the forebrain. The thalamus is a major sensory relay hub, which is involved in the processing of sensory inputs. Many of our sensory areas have secondary regions that play both major and minor roles in keeping us functioning. One such region is the amygdala, which plays an important role in both memory and emotion. The amygdala has to (afferent) and fro (efferent) connections with the thalamus, hypothalamus and hippocampus, among others and is mostly involved in detecting threats and/or danger ahead of conscious or cognitive awareness. So, even before the superior colliculus rolls into action, the amygdala has already recognised and initiated some form of reaction. Some of these amygdalae responses can be so fast that we react even before we are aware. A reaction that can lead us to be somewhat bewildered because we are aware that we have reacted, e.g. out of the path of a speeding car, but think ourselves lucky because we didn't see it . . . or so we thought!

These amygdalae responses are an aspect of our defensive mechanisms that hypnotherapy can actually help with, in resolving an anxiety disorder. The resultant, dysfunctional, anxiety is often a consequence of the brain being conditioned to respond to an unclear and non-present danger, that is, a danger that is, or not, actually present; or maybe one that is no longer so! This phenomenon is better understood and explained by classical or Pavlovian conditioning, aka Hebbian plasticity. One of the hallmarks of an anxiety disorder is avoidance and this can lull us into a false sense of security or achievement. The achievement, being, the nonresponse to an avoided stimuli. Avoidance can lead us to believe we have overcome the problem. whereas we are merely avoiding it, as in, no stimulus; no response! So, the takeaway from this article is, what you do not see, at least consciously, could save your life! That moment when you suddenly jump back from the kerb, just in time to save you from a speeding car; maybe with an exclamation . . . that was lucky! In reality, it was less likely to have been a case of luck and more likely to be the result of a highly evolved defence mechanism; tuned in to real avoidance. This is what the fear mechanism was really designed to do but we, being human, have developed it to beyond its real purpose and have perfected it to an art form of effective dysfunction! Hypnotherapy, as an alternative art form, is a really effective solution to a modern problem; you should try it!

Hypnotherapy stands out as one of the most effective strategic life management methods there is, especially in its ability to promote clear thinking and good states of mental wellness. The behaviours that make life challenging are often a result of too much stress, too little or poor quality sleep and too little by way of mental and emotional clarity! So, to get or take back control of your mind and your life, it makes perfect sense to use a methodology that addresses the subconscious brain's role in perpetuating negative, vague and ambiguous states of mind. Hypnosis helps us to create calm relaxing states of mind that make life work better! If you would like to address any concerns you have in this direction, or, if you just want the ability to make your life feel better, then why not make an appointment for a Free Consultation? Hypnosis gives you the ability to have a good life! 

My objective is to help people understand how and why we become illogically trapped into emotional experiences that may actually be happening but for reasons, we may never have imagined! If you want to know more about Hypnotherapy, why not make an appointment for a Free Consultation?

For more information on the Free Consultation - Go Here Or, to book your Free Consultation today, you can do so here


The Research: 

Researchers at the National Eye Institute (NEI) have defined a crucial window of time that mice need to key in on visual events. As the brain processes visual information, an evolutionarily conserved region known as the superior colliculus notifies other regions of the brain that an event has occurred. Inhibiting this brain region during a specific 100-millisecond window inhibited event perception in mice. Understanding these early visual processing steps could have implications for conditions that affect perception and visual attention, like schizophrenia and attention deficit hyperactivity disorder (ADHD). The study was published online in the Journal of Neuroscience. NEI is part of the National Institutes of Health.

"One of the most important aspects of vision is fast detection of important events, like detecting threats or the opportunity for a reward. Our result shows this depends on visual processing in the midbrain, not only the visual cortex," said Richard Krauzlis, Ph.D., chief of the Section on Eye Movements and Visual Selection at NEI and senior author of the study.

Visual perception -- one's ability to know that one has seen something -- depends on the eye and the brain working together. Signals generated in the retina travel via retinal ganglion cell nerve fibres to the brain. In mice, 85% of retinal ganglion cells connect to the superior colliculus. The superior colliculus provides the majority of early visual processing in these animals. In primates, a highly complex visual cortex takes over more of this visual processing load, but 10% of retinal ganglion cells still connect to the superior colliculus, which manages basic but necessary perceptual tasks.

One of these tasks is detecting that a visual event has occurred. The superior colliculus takes in information from the retina and cortex, and when there is sufficient evidence that an event has taken place in the visual field, neurons in the superior colliculus fire. Classical experiments into perceptual decision-making involve having a subject, like a person or a monkey, look at an image of the vertical grating (a series of blurry vertical black and white lines) and decide if or when the grating rotates slightly. In 2018, Krauzlis and Wang adapted these classic experiments for mice, opening up new avenues for research.

"Although we have to be cautious in translating data from mice to humans, because of the difference in visual systems, mice have many of the same basic mechanisms for event detection and visual attention as humans. The genetic tools available for mice allow us to study how specific genes and neurons are involved in controlling perception," said Lupeng Wang, Ph.D., first author of the study.

In this study, Wang and colleagues used a technique called optogenetics to tightly control the activity of the superior colliculus over time. They used genetically modified mice so that they could turn neurons in the superior colliculus on or off using a beam of light. This on-off switch could be timed precisely, enabling the researchers to determine exactly when the neurons of the superior colliculus were required for detecting visual events. The researchers trained their mice to lick a spout when they'd seen a visual event (a rotation in the vertical grating) and to avoid licking the spout otherwise.

Inhibiting the cells of the superior colliculus made the mice less likely to report that they'd seen an event, and when they did, their decision took longer. The inhibition had to occur within a 100 millisecond (one-tenth of a second) interval after the visual event. If the inhibition was outside that 100-millisecond timeframe, the mouse's decisions were mostly unaffected. The inhibition was side-specific: because the retinal cells cross over and connect to the superior colliculus on the opposite side of the head (the left eye is connected to the right superior colliculus and vice versa), inhibiting the right side of the superior colliculus depressed responses to stimuli on the left side, but not on the right.

"The ability to temporarily block the transmission of neural signals with such precise timing is one of the great advantages of using optogenetics in mice and reveals exactly when the crucial signals pass through the circuit," said Wang.

Interestingly, the researchers found that the deficits with superior colliculus inhibition were much more pronounced when the mice were forced to ignore things happening elsewhere in their visual field. Essentially, without the activity of the superior colliculus, the mice were unable to ignore distracting visual events. This ability to ignore visual events, called visual attention, is critical for navigating the complex visual environments of the real world.

"The superior colliculus is a good target for probing these functions because it has a neatly organized map of the visual world. And it is connected to less neatly organized regions, like the basal ganglia, which are directly implicated in a wide range of neuropsychiatric disorders in humans," said Krauzlis. "It's sort of like holding the hand of a friend as you reach into the unknown."


Story Source:

Materials provided by NIH/National Eye InstituteNote: Content may be edited for style and length.

Journal Reference:

  1. Lupeng Wang, Kerry McAlonan, Sheridan Goldstein, Charles R. Gerfen, Richard J. Krauzlis. A causal role for mouse superior colliculus in visual perceptual decision-makingThe Journal of Neuroscience, 2020; JN-RM-2642-19 DOI: 10.1523/JNEUROSCI.2642-19.2020

Cite This Page:

NIH/National Eye Institute. "It's now or never: Visual events have 100 milliseconds to hit brain target or go unnoticed: Mouse study reveals key details about visual processing." ScienceDaily. ScienceDaily, 7 April 2020. <www.sciencedaily.com/releases/2020/04/200407170742.htm>