Speech processing while unconscious: Sleep inhibits action but not preparation and meaning

In a team effort between the Medical Research Council Cognition and Brain Sciences Unit (Cambridge, UK) and the Laboratory of Cognitive and Psycholinguistics Sciences, Ecole Normale Superiore (Paris), part of what we are capable of while sleeping has been unravelled.

People were asked to classify words belonging to one of two categories – animals or objects – by pressing buttons with the left or the right hand, and continued to do so until they have fallen asleep. Their brain activity indicated that they were able to decode the meaning of the words and intended to act but the unconscious state during sleep prevented them from responding (no movement of the fingers).

This result indicates that once a rule (animals press left/objects press right) is established during wakefulness it can still be implemented even during sleep. This means that the decoding networks in the brain process the spoken words and that information (if it is an animal or an object for instance) is passed to a motor plan signaling the intention and subsequent action. During sleep that action is inhibited (we do not purposefully move during sleep) but this study has found that the meaning extraction and subsequent action preparation remained but was slower and lasted longer.

To confirm this result a second study tested whether people could classify word or nonwords (like boat or foat). A similar pattern emerged, showing appropriate brain preparation activity for left or right button presses even if responses were inhibited by the sleep mechanisms.

So what we can do while we’re sleeping is quite an interesting question. If we still have language processing at this point, how much can we retain? Or is it that it’s linked to action, even if it’s surpressed? I’d be interested to know more about if we can do more processing than just word categorization – like, could you plan acting on given sentences while sleeping, except again be inhibited from acting on them?

If we mapped particular kinds of imagined actions to particular brain patterns while awake, it’d then be interesting to see if we can reproduce those while asleep, too. I’d love to do this, but… neuroling is a lot of money. ^^;

My sleeping self DEFINITELY has learned the patterns of where my alarm clock is and how to turn it off

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s