neděle 4. prosince 2011
Thalamic deactivation at sleep onset precedes that of the cerebral cortex in humans
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2840430/
Why Daydreamers Are More Creative
http://www.psychologytoday.com/blog/beautiful-minds/201102/why-daydreamers-are-more-creative
When most of us fall asleep, the brain network that involves attention to the outside world (the working memory network consisting primarily of the lateral frontal and parietal cortices) deactivates and our default brain network (medial prefrontal and posterior cingulate cortices) takes over. The discovery of the default brain network is important, as it involves various aspects of our self, such as our self-representations, dreams, imagination, current concerns, autobiographical memory and perspective-taking ability. Those with higher default network activity during rest have a tendency to daydream more frequently, which makes sense if one thinks of the default network as involving our inner stream of consciousness.
. In most people, the working memory network and the default network "anticorrelate" with each other,
Creative folks and those with schizophrenia tend to have an overactive default network. Prior research has suggested that the thing that seems to differentiate creative but functional individuals from those in a mental institution is that the functional folks appear to have the ability to engage both brain networks, and they can use their working memory network to control their attention. Those who lose grip on reality and become paranoid and delusional have let the floodgates down, so to speak, letting too much of their default network control their attention
The creativity test they used has been linked in prior studies to Openness to Experience and frequency of visual hypnagogic experiences (e.g. lucid dreaming, hallucinations), which in turn have been associated with vividness of mental imagery.
The researchers found that the more creative the participant, the more activity in their default-mode network was altered. Particularly, creative individuals had difficulty suppressing the precuneus area of their default network while engaging in the more effortful working memory task. The precuneus is the area of the default network that typically displays the highest levels of activation during rest (when a person is not focusing on an external task). The precuneus has been linked to self-related mental representations and episodic memory retrieval.
When most of us fall asleep, the brain network that involves attention to the outside world (the working memory network consisting primarily of the lateral frontal and parietal cortices) deactivates and our default brain network (medial prefrontal and posterior cingulate cortices) takes over. The discovery of the default brain network is important, as it involves various aspects of our self, such as our self-representations, dreams, imagination, current concerns, autobiographical memory and perspective-taking ability. Those with higher default network activity during rest have a tendency to daydream more frequently, which makes sense if one thinks of the default network as involving our inner stream of consciousness.
. In most people, the working memory network and the default network "anticorrelate" with each other,
Creative folks and those with schizophrenia tend to have an overactive default network. Prior research has suggested that the thing that seems to differentiate creative but functional individuals from those in a mental institution is that the functional folks appear to have the ability to engage both brain networks, and they can use their working memory network to control their attention. Those who lose grip on reality and become paranoid and delusional have let the floodgates down, so to speak, letting too much of their default network control their attention
The creativity test they used has been linked in prior studies to Openness to Experience and frequency of visual hypnagogic experiences (e.g. lucid dreaming, hallucinations), which in turn have been associated with vividness of mental imagery.
The researchers found that the more creative the participant, the more activity in their default-mode network was altered. Particularly, creative individuals had difficulty suppressing the precuneus area of their default network while engaging in the more effortful working memory task. The precuneus is the area of the default network that typically displays the highest levels of activation during rest (when a person is not focusing on an external task). The precuneus has been linked to self-related mental representations and episodic memory retrieval.
pátek 2. prosince 2011
lidske-chovani-nemusi-vyplyvat-z-hodnot-ale-naopak
http://scienceworld.cz/clovek/lidske-chovani-nemusi-vyplyvat-z-hodnot-ale-naopak-6581
středa 30. listopadu 2011
Cognitive Load
Light intensity affects pupil diameter: the pupil contracts in bright
environments and it dilates in the dark. Interestingly, cognitive load
also affects pupil diameter, with the pupil dilating in response to
increased cognitive load. This effect is called the task evoked
pupillary response (TEPR) [1]. Thus, changes in pupil diameter are
physiological measures of cognitive load; however changes in lighting
introduce noise into the estimate.
Game Transfer Phenomena
Vidění obrazů ze hry při mrknutí - zjistit přoč jak to funguje a jak to udělat i bez něj.
Při mrknutí obraz kvalitnejší než při zavřených očích . Někdy je obaz lépe vidět při otveřenejch než zavřenejch.
tetris efekt jak zvětšit ?
-pozornost , zájem , nová věc , délka
hypokampus to cortex ?
vrsty?
Mrkání ?
LTP?
visual cortex ?
cílená aktivace ?
Při mrknutí obraz kvalitnejší než při zavřených očích . Někdy je obaz lépe vidět při otveřenejch než zavřenejch.
tetris efekt jak zvětšit ?
-pozornost , zájem , nová věc , délka
hypokampus to cortex ?
vrsty?
Mrkání ?
LTP?
visual cortex ?
cílená aktivace ?
How and when people see pieces from the computer game in their sleep tells of the role dreaming plays in learning
17 subjects they
trained to play Tetris, more than 60 percent reported dreaming of images
associated with the game. And the researchers found that when and how
the study�s sleeping participants saw these images helps confirm the
idea that the brain uses dreaming to reinforce learning. They reported
their findings in the
During slow-wave sleep, the hippocampus--a region of the brain that stores recent, episodic memories about discrete events--replays its files for the neocortex, home to more permanent memories. The communication between the two brain areas at this time is one way, from the hippocampus to the neocortex. During the REM dreaming that follows, though, the flow of information flips, from the neocortex back to the hippocampus. Stickgold suggested that once the neocortex connects the new memories to others in storage, it sends a message back to the hippocampus to erase them.
In this latest round of experimentation, Stickgold and his team probed yet a third phase of dreaming--the hypnagogic period that occurs within the first hour of sleep. They studied three different sets of subjects who all played Tetris over the course of three days--playing for two hours in the morning and in the evening on the first day, and for an hour each morning and evening on the following days of the study. Twelve of their subjects had never before played the game. Another 10 were experts who had logged between 50 and 500 hours of Tetris prior to the experiment. And the remaining five were amnesiacs, having no short-term memory due to lesions in the hippocampus.
Seventeen of these 27 subjects reported seeing the same images during
hypnagogic sleep--namely falling geometric pieces that, if placed
properly, rack up points in Tetris. And, interestingly, most of these
reports occurred after the second night of the study. This delay
suggests to the researchers that the need to learn may in part prod the
brain into dreaming. �It�s as if the brain needs more time or more play
before it decides, �Okay, this is something that I really need to deal
with at sleep onset,� Stickgold says.
In fact, the learning curve for the game--measured by total points earned--was quite different for the three groups. Whereas both the experts and the novices showed considerable improvement, the amnesiacs did not. And this progress was somewhat reflected in the dream reports. The nine novices who were initially worst at the game were the very same who reported seeing falling pieces during sleep onset--suggesting again that the more a subject needed to learn, the more his or her brain reviewed the material. Only five experts saw the imagery. Two of them, however, described Tetris images associated not with the version they played in the lab but with the version they had played on Nintendo machines--a twist that Stickgold attributes to the integrative process.
Perhaps most surprising, three of the five amnesiacs described having the same kinds of hypnagogic dreams as the normal subjects. The researchers had assumed that the amnesiacs� dreams--especially those during the hypnagogic phase--would have nothing to do with recent events, if they occurred at all, due to the damage to their short-term memory centers. �We thought that if there�s one part of sleep that depends on episodic memories, which amnesiacs lack, it's sleep onset,� Stickgold says.
But even for these individuals, most of whom did not remember the game from one day to the next and had to be taught all over again, the Tetris dreams seemed to affect their waking behavior. Co-author David Roddenberry, an undergraduate at Harvard, noticed that one of the amnesiacs who didn�t remember the game nevertheless placed her fingers on the computer keys used in playing at the start of a session. �She did not quite know what she was doing and yet she did know what she was doing,� Stickgold comments. �In a way, this is Freud�s unconscious--things activated in our brain that are in fact memories that guide our behavior but are not conscious.�
To try to understand this barrier between waking and sleep, the researchers also compared the differences in reports of images or thoughts of Tetris both before sleep onset and right after. Curiously, thoughts about Tetris not associated with seeing falling pieces were more prevalent before sleep, whereas reports of images were more common during sleep. �What was most striking about the data,� the researchers write in the Science paper, �was the strong similarity in reports from different individuals.� All the subjects dreamed of pieces falling and sometimes rotating or fitting into empty spaces--and none reported seeing the picture surrounding the pieces, the scoreboard or the keyboard.
During slow-wave sleep, the hippocampus--a region of the brain that stores recent, episodic memories about discrete events--replays its files for the neocortex, home to more permanent memories. The communication between the two brain areas at this time is one way, from the hippocampus to the neocortex. During the REM dreaming that follows, though, the flow of information flips, from the neocortex back to the hippocampus. Stickgold suggested that once the neocortex connects the new memories to others in storage, it sends a message back to the hippocampus to erase them.
In this latest round of experimentation, Stickgold and his team probed yet a third phase of dreaming--the hypnagogic period that occurs within the first hour of sleep. They studied three different sets of subjects who all played Tetris over the course of three days--playing for two hours in the morning and in the evening on the first day, and for an hour each morning and evening on the following days of the study. Twelve of their subjects had never before played the game. Another 10 were experts who had logged between 50 and 500 hours of Tetris prior to the experiment. And the remaining five were amnesiacs, having no short-term memory due to lesions in the hippocampus.
Image: after STICKGOLD et al., Science
THOUGHTS AND IMAGES.
Reports about Tetris differed depending on when they occurred. Thoughts
alone were more common among subjects before sleep, and images were
more prevalent after sleep. In all, though, the reports were
astonishingly similar.
|
In fact, the learning curve for the game--measured by total points earned--was quite different for the three groups. Whereas both the experts and the novices showed considerable improvement, the amnesiacs did not. And this progress was somewhat reflected in the dream reports. The nine novices who were initially worst at the game were the very same who reported seeing falling pieces during sleep onset--suggesting again that the more a subject needed to learn, the more his or her brain reviewed the material. Only five experts saw the imagery. Two of them, however, described Tetris images associated not with the version they played in the lab but with the version they had played on Nintendo machines--a twist that Stickgold attributes to the integrative process.
Perhaps most surprising, three of the five amnesiacs described having the same kinds of hypnagogic dreams as the normal subjects. The researchers had assumed that the amnesiacs� dreams--especially those during the hypnagogic phase--would have nothing to do with recent events, if they occurred at all, due to the damage to their short-term memory centers. �We thought that if there�s one part of sleep that depends on episodic memories, which amnesiacs lack, it's sleep onset,� Stickgold says.
But even for these individuals, most of whom did not remember the game from one day to the next and had to be taught all over again, the Tetris dreams seemed to affect their waking behavior. Co-author David Roddenberry, an undergraduate at Harvard, noticed that one of the amnesiacs who didn�t remember the game nevertheless placed her fingers on the computer keys used in playing at the start of a session. �She did not quite know what she was doing and yet she did know what she was doing,� Stickgold comments. �In a way, this is Freud�s unconscious--things activated in our brain that are in fact memories that guide our behavior but are not conscious.�
To try to understand this barrier between waking and sleep, the researchers also compared the differences in reports of images or thoughts of Tetris both before sleep onset and right after. Curiously, thoughts about Tetris not associated with seeing falling pieces were more prevalent before sleep, whereas reports of images were more common during sleep. �What was most striking about the data,� the researchers write in the Science paper, �was the strong similarity in reports from different individuals.� All the subjects dreamed of pieces falling and sometimes rotating or fitting into empty spaces--and none reported seeing the picture surrounding the pieces, the scoreboard or the keyboard.
Game Transfer Phenomena - Tetris effect
The Tetris effect occurs when people devote sufficient time and attention to an activity that it begins to overshadow their thoughts, mental images, and dreams
Stickgold et al. (2000) have proposed that Tetris imagery is a separate form of memory, likely related to procedural memory. This is from their research in which they showed that people with anterograde amnesia, unable to form new declarative memories, reported dreaming of falling shapes after playing Tetris during the day, despite not being able to remember playing the game at all.[3] A recent Oxford study (2009) suggests Tetris-like video games may help prevent the development of traumatic memories. If the video game treatment is played soon after the traumatic event, the preoccupation with Tetris shapes is enough to prevent the mental recitation of traumatic images, thereby decreasing the accuracy, intensity, and frequency of traumatic reminders. "We suggest it specifically interferes with the way sensory memories are laid down in the period after trauma and thus reduces the number of flashbacks that are experienced afterwards," summarizes Dr. Emily Holmes, who led the study.[4][5]
Stickgold et al. (2000) have proposed that Tetris imagery is a separate form of memory, likely related to procedural memory. This is from their research in which they showed that people with anterograde amnesia, unable to form new declarative memories, reported dreaming of falling shapes after playing Tetris during the day, despite not being able to remember playing the game at all.[3] A recent Oxford study (2009) suggests Tetris-like video games may help prevent the development of traumatic memories. If the video game treatment is played soon after the traumatic event, the preoccupation with Tetris shapes is enough to prevent the mental recitation of traumatic images, thereby decreasing the accuracy, intensity, and frequency of traumatic reminders. "We suggest it specifically interferes with the way sensory memories are laid down in the period after trauma and thus reduces the number of flashbacks that are experienced afterwards," summarizes Dr. Emily Holmes, who led the study.[4][5]
The role of the right temporoparietal junction in intersensory conflict: detection or resolution?
The right temporoparietal junction (rTPJ) is a polysensory cortical area
that plays a key role in perception and awareness. Neuroimaging
evidence shows activation of rTPJ in intersensory and sensorimotor
conflict situations, but it remains unclear whether this activity
reflects detection or resolution of such conflicts. To address this
question, we manipulated the relationship between touch and vision using
the so-called mirror-box illusion. Participants’ hands lay on either
side of a mirror, which occluded their left hand and reflected their
right hand, but created the illusion that they were looking directly at
their left hand. The experimenter simultaneously touched either the
middle (D3) or the ring finger (D4) of each hand. Participants judged,
which finger was touched on their occluded left hand. The visual
stimulus corresponding to the touch on the right hand was therefore
either congruent (same finger as touch) or incongruent (different finger
from touch) with the task-relevant touch on the left hand. Single-pulse
transcranial magnetic stimulation (TMS) was delivered to the rTPJ
immediately after touch. Accuracy in localizing the left touch was worse
for D4 than for D3, particularly when visual stimulation was
incongruent. However, following TMS, accuracy improved selectively for
D4 in incongruent trials, suggesting that the effects of the conflicting
visual information were reduced. These findings suggest a role of rTPJ
in detecting, rather than resolving, intersensory conflict.
Remote Excitation of Neuronal Circuits Using Low-Intensity, Low-Frequency Ultrasound
Article
Notes:
By transmitting US waveforms through hippocampal slice cultures and ex vivo mouse brains, we determined LILFU is capable of remotely and noninvasively exciting neurons and network activity. Our results illustrate that LILFU can stimulate electrical activity in neurons by activating voltage-gated sodium channels, as well as voltage-gated calcium channels. The LILFU-induced changes in neuronal activity were sufficient to trigger SNARE-mediated exocytosis and synaptic transmission in hippocampal circuits. Because LILFU can stimulate electrical activity and calcium signaling in neurons as well as central synaptic transmission we conclude US provides a powerful tool for remotely modulating brain circuit activity.
*Transcranial ultrasonography of the basilar artery has been shown to trigger auditory sensations in human subjects Other studies have reported similar observations in animals during delivery of transcranial US and at least one underlying mechanism is thought to involve the direct stimulation of auditory nerve fibers by US
*The frequency of US we chose for the construction of LILFU waveforms (0.44–0.67 MHz) represents a range where optimal gains have been previously reported between transcranial US transmission and brain absorption. Based on modeling data of transmission and attenuation coefficients, as well as experimental data examining the transmission of US through ex vivo human skulls, the optimal gain for the transcranial US transmission and brain absorption is between 0.60 and 0.70 MHz [25], [26]. Based on our observations and the findings of others, it is likely that LILFU fields can be transmitted through skulls into the intact brain for gross neurostimulation purposes similar to methods using rTMS. In order to achieve targeted neurostimulation however, it will be necessary to focus LILFU fields.
*It is possible to focus US fields using a variety of approaches. Pulsed US (<1 MHz) can be focused through human skulls to points within 1 mm of intended loci using phased US transducer arrays [6], [8], [59]. Based on observations reported in studies designed to investigate US field focusing through human skulls [6], [8], [59], US may be able to confer a spatial resolution similar to those achieved by currently implemented neuromodulation strategies such as vagal nerve stimulation and DBS, which have been shown to possess high therapeutic value [1], [60].
Notes:
low-intensity, low-frequency ultrasound (LILFU)
By transmitting US waveforms through hippocampal slice cultures and ex vivo mouse brains, we determined LILFU is capable of remotely and noninvasively exciting neurons and network activity. Our results illustrate that LILFU can stimulate electrical activity in neurons by activating voltage-gated sodium channels, as well as voltage-gated calcium channels. The LILFU-induced changes in neuronal activity were sufficient to trigger SNARE-mediated exocytosis and synaptic transmission in hippocampal circuits. Because LILFU can stimulate electrical activity and calcium signaling in neurons as well as central synaptic transmission we conclude US provides a powerful tool for remotely modulating brain circuit activity.
*Transcranial ultrasonography of the basilar artery has been shown to trigger auditory sensations in human subjects Other studies have reported similar observations in animals during delivery of transcranial US and at least one underlying mechanism is thought to involve the direct stimulation of auditory nerve fibers by US
*The frequency of US we chose for the construction of LILFU waveforms (0.44–0.67 MHz) represents a range where optimal gains have been previously reported between transcranial US transmission and brain absorption. Based on modeling data of transmission and attenuation coefficients, as well as experimental data examining the transmission of US through ex vivo human skulls, the optimal gain for the transcranial US transmission and brain absorption is between 0.60 and 0.70 MHz [25], [26]. Based on our observations and the findings of others, it is likely that LILFU fields can be transmitted through skulls into the intact brain for gross neurostimulation purposes similar to methods using rTMS. In order to achieve targeted neurostimulation however, it will be necessary to focus LILFU fields.
*It is possible to focus US fields using a variety of approaches. Pulsed US (<1 MHz) can be focused through human skulls to points within 1 mm of intended loci using phased US transducer arrays [6], [8], [59]. Based on observations reported in studies designed to investigate US field focusing through human skulls [6], [8], [59], US may be able to confer a spatial resolution similar to those achieved by currently implemented neuromodulation strategies such as vagal nerve stimulation and DBS, which have been shown to possess high therapeutic value [1], [60].
Ethics of neural enhancement using noninvasive brain stimulation
Article
Notes:
Another area where the potential of cognitive enhancement
holds great promise is language learning.
Anodal tDCS over Broca’s area has been shown to
improve the ability of subjects to learn new object
names and may also enhance the ability to learn
novel grammar.14,15.In other investigations, TMS
and tDCS of language-related regions of the left
hemisphere has been shown to induce faster object
naming,16,17 and anodal tDCS applied to the left prefrontal
cortex has been shown to transiently improve
verbal fluency.18
-----------------------------------------------------------
After inhibitory noninvasive brain
stimulation of the right DLPFC, subjects were more
likely to accept low offers, even though they still perceived
them as being unfair. It seems as though subjects
were more motivated to act in their self-interest
than to abstain from a reward for the sake of fairness.
TMS and tDCS of the DLPFC have also been shown
to manipulate behavior on a variety of other rewardseeking
tasks.38
prefrontal cortex. Science 2006;314:829–832.
activity in the prefrontal cortex: a direct current stimulation
study. J Neurosci 2007;27:12500–12505.
Notes:
Another area where the potential of cognitive enhancement
holds great promise is language learning.
Anodal tDCS over Broca’s area has been shown to
improve the ability of subjects to learn new object
names and may also enhance the ability to learn
novel grammar.14,15.In other investigations, TMS
and tDCS of language-related regions of the left
hemisphere has been shown to induce faster object
naming,16,17 and anodal tDCS applied to the left prefrontal
cortex has been shown to transiently improve
verbal fluency.18
- 14. Flo¨el A, Ro¨sser N, Michka O, Knecht S, Breitenstein C.
Noninvasive brain stimulation improves language learning.
J Cogn Neurosci 2008;20:1415–1422.
J Cogn Neurosci 2008;20:1415–1422.
- 15. de Vries MH, Barth AC, Maiworm S, Knecht S, Zwisterlood
P, Flo¨el A. Electrical stimulation of Broca’s area enhances
implicit learning of an artificial grammar. J Cogn
Neurosci Epub 2009 Nov 19.
implicit learning of an artificial grammar. J Cogn
Neurosci Epub 2009 Nov 19.
- 17. Sparing R, Dafotakis M, Meister IG, Thirugnanasambandam
N, Fink GR. Enhancing language performance with
non-invasive brain stimulation: a transcranial direct current
non-invasive brain stimulation: a transcranial direct current
-----------------------------------------------------------
After inhibitory noninvasive brain
stimulation of the right DLPFC, subjects were more
likely to accept low offers, even though they still perceived
them as being unfair. It seems as though subjects
were more motivated to act in their self-interest
than to abstain from a reward for the sake of fairness.
TMS and tDCS of the DLPFC have also been shown
to manipulate behavior on a variety of other rewardseeking
tasks.38
- 37. Knoch D, Pascual-Leone A, Meyer K, Treyer V, Fehr E.
prefrontal cortex. Science 2006;314:829–832.
- 38. Fecteau S, Knoch D, Fregni F, Sultani N, Boggio P, Pascual-
activity in the prefrontal cortex: a direct current stimulation
study. J Neurosci 2007;27:12500–12505.
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