You know that crap that we don’t timeslice or multitask?  Do you not walk around and talk on the phone?  What about when you are cooking?  (You DO cook, right?)  You are thinking of the next ingredient to add as you tend to the dissolution, sautéing, or mixing of what is in front of you.

In truth, every second of (almost) every minute of the day, your brain reacts to and inferfaces with two sets of data- the input from your surroundings (you know those ‘five senses’ things- the smells, the light, the noise) and the thoughts and memories that teem around your brain.

This is the nature of normal cognitive function.  Which, should we succumb to – or were born with- mental illness is not the normal situation. The ability to maintain and react with internal and external stimuli would be impaired- or totally absent.

Dr. Michael Halassa (NYU) knew that interactions between the cortex and the thalamus are vital to this ability to interact with external and internal stimuli.  His hunch that the thalamic reticular nucleus (TRN) was the key pathway proved to be true- as he demonstrated in his mouse studies.  In this current study, the results of which were presented in Cell (with co-authors Drs. Chen, Wimmer, Brunetti, Zhoa, Zikopoulos, Wang, Brown, and Wilson), it was demonstrated that the external sensory and internal limbic processing is critical for normal cognitive function.

The brain’s cortex is the key for our higher cognitive function; the thalamus directs the information flow of internal and external information- including that which will find its way to the cortex. The TRN, the layer between these two brain  segments, seems to be the gateway.  To study this gateway’s function, Dr. Halassa relied on sleep modes, when the bulk of the brain activity is internally focused.  During sleep, visual information is precluded from reaching the cortex- but once we are awake, that pathway is open and functional.

Halassa’s group managed to find a way to flip this switch while the mice were awake. In so doing, the group was able to determine that sleep-deprived mice had difficulty finding food- until the switch was flipped on- and then they could more readily find their meals. Conversely, well-rested mice failed to find their food when that same switch was turned off.

Of course, there is no data to indicate if similar circuitry exists in humans. But, if it does, it presents great promise in the treatment of schizophrenia or autism. Drugs could be developed that target the relevant neurons- similar to the deep brain stimulation that is used now- but now in a non-invasive fashion.

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