News on working memory

Glia cells are the Cinderella’s of neuroscience – mostly ignored but sometimes making it, to be the hit of the party. In the cortex, the neurons live in a sea of glia cells. Lately there is another hint that they have important functions, an item in the Scientific American (here) says they are important to working memory. It may also explain stoned-type-logic-thinking.

To study how marijuana impairs working memory, Giovanni Marsicano of the University of Bordeaux in France and his colleagues removed cannabinoid receptors—proteins that respond to marijuana’s psychoactive ingredient THC—from neurons in mice. These mice, it turned out, were just as forgetful as regular mice when given THC: they were equally poor at memorizing the position of a hidden platform in a water pool. When the receptors were removed from astrocytes, however, the mice could find the platform just fine while on THC. … this is one of the first studies to suggest that glia play a key role in conscious thought. “It’s very likely that astrocytes have many more functions than we thought,” Marsicano says. “Certainly their role in cognition is now being revealed.”

Attention and consciousness act separately

I have posted on this before (here and here) but I am going to again, prompted by Tallon-Baudry’s talk at the Turing 2012 Consciousness Event (video). The experimental detail covered in the talk is from a paper with Wyart and Dehaene (citation below). She reviewed this area of research recently (citation below). Abstract:

Consciousness, as described in the experimental literature, is a multi-faceted phenomenon, that impinges on other well-studied concepts such as attention and control. Do consciousness and attention refer to different aspects of the same core phenomenon, or do they correspond to distinct functions? One possibility to address this question is to examine the neural mechanisms underlying consciousness and attention. If consciousness and attention pertain to the same concept, they should rely on shared neural mechanisms. Conversely, if their underlying mechanisms are distinct, then consciousness and attention should be considered as distinct entities. This paper therefore reviews neurophysiological facts arguing in favor or against a tight relationship between consciousness and attention. Three neural mechanisms that have been associated with both attention and consciousness are examined (neural amplification, involvement of the fronto-parietal network, and oscillatory synchrony), to conclude that the commonalities between attention and consciousness at the neural level may have been overestimated. Last but not least, experiments in which both attention and consciousness were probed at the neural level point toward a dissociation between the two concepts. It therefore appears from this review that consciousness and attention rely on distinct neural properties, although they can interact at the behavioral level. It is proposed that a “cumulative influence model,” in which attention and consciousness correspond to distinct neural mechanisms feeding a single decisional process leading to behavior, fits best with available neural and behavioral data. In this view, consciousness should not be considered as a top-level executive function but should rather be defined by its experiential properties.

 

She outlines three ways of relating consciousness and attention.

Gateway hypothesis: attention and consciousness reflect related concepts, much as temperature and heat. The idea that attention acts as a gateway for consciousness has been formalized in influential theories of consciousness: those events that enter consciousness are those that have been selected and amplified by attention.

Reverse dependence hypothesis: alternatively, whether a stimulus has been detected or not at the neural level could trigger different attentional mechanisms.

Cumulative influence hypothesis: attention and consciousness would be implemented by distinct neural mechanisms, but would both influence, although with different weights, the final report of the subject on the presence or absence of a stimulus. This hypothesis postulates the existence of a decision variable that would accumulate mainly consciousness-related neural activity, but also, to a lesser extent, attention-related neural activity. Behavioral reports based on this decision variable could therefore show an interaction between attention and consciousness, whereas neural variables could be related solely to attention and consciousness.

 

Intuition favours the gateway model but Tallon-Baudry puts forward evidence for the cumulative model but looking for connections (or lack of connections) in the neural correlates of attention and consciousness. If they have no joint neural correlates then how can they influence one another. The obvious overlaps are neural amplification, involvement of the fronto-parietal network, and oscillatory synchrony; none of these appear solid.

To summarize, attention does operate in sensory regions, but neural amplification by attention appears functionally distinct from the neural amplification related to consciousness: attention does not shorten response latencies, as more contrasted objects would, attention-related and consciousness- related neural activities in retinotopic areas can be dissociated . There is growing evidence that events that do not reach consciousness nevertheless activate parietal and frontal regions, suggesting that they are not sufficient for consciousness to emerge. Because frontal regions are not always activated, one can even wonder whether they are necessary. An alternative possibility is that they reflect a consequence of consciousness, rather than a cause. Last, oscillatory synchrony is not associated exclusively with a single process, be it feature binding, memory and learning, attention, or consciousness, but should rather be considered as a generic mechanism governing neural interactions .

 

Tallon-Baudry points out a few of the weaknesses of the cummulative model (the place of decisional bias, the dangers of fMRI data, the other types of attention besides spatial) but insists that to the present it best fits the evidence.

Even if the cumulative influence hypothesis has its limitations, it is so far the model that fits best with experimental data. Interestingly this model points toward the existence of a sensory neural activity related to consciousness, uncontaminated by other cognitive processes such as attention. Such an activity could potentially be very close to the immediate subjective experience of the subject. This is reminiscent of the idea of phenomenal awareness, that could be distinct from cognitive access.

 

ResearchBlogging.org

V. Wyart, S. Dehaene, & C. Tallon-Baudry (2012). Early dissociation between neural signatures of endogenous spatial attention and perceptual awareness during visual masking Frontiers in Human Neuroscience DOI: 10.3389/fnhum.2012.00016

Catherine Tallon-Baudry (2012). On the neural mechanisms subserving consciousness and attention Frontiers in Psychology DOI: 10.3389/fpsyg.2011.00397

Hypnosis in the lab

    V Bell has a article in the Observer (here) on the scientific study of hypnosis.

Interesting thoughts:

The easy of suggestibility is partially inherited and is spread across the population in a bell curve (like height). You are easy to hypnotize or hard or in between. You can go into a deep trace or be only mildly affected.

There are differences in the brain that correlate with suggestibility. Scans can tell good faking from real hypnotic traces.

“it was possible to “switch off” automatic word reading and abolish the Stroop effect – a psychological phenomenon that demonstrates a conflict between meanings, such as where we are much slower to identify the ink colour of a word when the word itself describes a different hue. Furthermore, when this experiment was run in a brain scanner, participants showed much lower activation in both the anterior cingulate cortex, an area known to be particularly involved in resolving conflict between competing demands, and the visual cortex, which is crucial for recognising words. Although this may seem like a technicality, to the scientific world it was a strikingly persuasive demonstration that hypnosis could apparently disassemble an automatic and well-established psychological effect in a manner consistent with the brain processes that support it.”

Where are the genes for intelligence?

Kevin Mitchell has a posting at Wiring the Brain (here) on the genetics of intelligence. This is a little off the subject of this blog, consciousness, but it is an interesting inversion of thought which happens often in brain science – turning ideas on their heads, so to speak.

He points out that we have known for a long time that intelligence/IQ/g is inherited to a significant degree. And now that we have the human genome available, we should be able to figure out which genes are important to intelligence. But, we have found too many with some small effect on intelligence and too few, well none, with any sizable effect. So we cannot find the gene/s ‘for intelligence’ that we expected.

It seems like we have genes that together give us a healthy, fit, smart individual. No single outstanding genes ‘for healthy’, ‘for fit’ or ‘for smart’. Instead we have to deal with failure of a gene (from a large group) any one of which could leave us sick, unfit and/or stupid. No genes ‘for intelligence’ but rather alleles/mutations ‘for stupidity’.

If this subject interests you, read the original post linked above. If not than simply think of it as an example of how models have to sometimes by inverted or even turned inside out in the light of evidence.

Neural correlates of consciousness

Some say that ‘we are our connectome’ – but – it seems that what functionally connects is constantly changing. And according to Wolf Singer timing is important. The temporal is as significant as the spatial. This was the message of Singer’s presentation at Turing Consciousness 2012 in Montreal (video here). He points out that the brain has a small world structure, is massively parallel in communication with co-existance of local and global states. This implies that there must be a mechanism for dynamic routing and rapid reconfiguration of functional networks. This can be accomplish with temporal coordination.

 

The main material in this talk came from a 2007 paper (citation below). By comparing subliminal and conscious perception using EEG measuring both the power and the synchronization across the frequency range, time course, and scalp location they characterized the neural events that mark consciousness. Here are parts of the discussion section of the paper:

 

The first (80 ms) electrographic difference between conscious and non-conscious stimulus processing was increased phase-locking of induced gamma oscillations across widely distributed cortical regions. This suggests that early large-scale synchronization could be the event that triggers ignition of the global workspace of consciousness, as postulated by Dehaene and Naccache …

 

This is interesting because it is the phase-locking that stands out. It seems like local processing and global processing are going on at the same time but not interfering with one another.

Our results show similar activation patterns at individual electrodes in the visible (conscious) and invisible (subliminal) conditions, suggesting that the same neural generators are activated in both cases. In contrast, phase synchronization across electrodes clearly differentiated between conditions, suggesting enhanced long-range coordination of oscillatory activity only in the visible (conscious) condition. Several authors have proposed that conscious perception should be related to coordinated dynamical states of the cortical network, rather than to the activation of specific brain regions. Our results offer direct support for this notion … in line with a recent proposal relating unconscious processing of information with local coordination of neural activity in resonant loops of medium range and relating conscious perception with global coordination of distant neural activity by long-range synchronization. Interestingly, the global long-distance synchronization found in the visible condition was very transient and the earliest event differentiating conscious from nonconscious processing. After this, other electrophysiological measures, such as P3a and theta oscillations, continue to differentiate between consciously and nonconsciously perceived words. This suggests that long-distance synchronization plays a role in triggering the cognitive processes associated with conscious awareness. However, it remains to be clarified through which mechanism long-distance synchronization exerts an impact on subsequent cognitive processes.

 

The authors distinguish between different aspects of consciousness – its existence, sensory awareness, attentional effects, prediction of near future and connection to working memory.

In contrast to previous experiments, the results of which suggest a late wave of activation as correlate of sensory awareness, our results indicate that access to consciousness is triggered by an early coordination (synchronization) of widely distributed neuronal assemblies starting as early as 80 ms after stimulus presentation … Together, the data suggest that only consciously perceived stimuli give rise to a cascade of processes that have distinct electrophysiological signatures. In summary, these consisted of (1) an early and global phase-locking of gamma oscillations, (2) an enhancement of a P3a-like component of the ERP and of sustained theta oscillations over frontal areas that are likely to reflect transfer and maintenance of the perceived stimuli in working memory, and (3) an enhancement of power and phase-locking of gamma oscillations before test stimulus presentation that may be a correlate of the anticipation of the matching between short-term memory contents and sensory input. …It remains to be clarified whether the early large-scale synchronization is already the neuronal correlate of phenomenal awareness or whether awareness emerges only from the entirety of the processes following this coordinated state.

ResearchBlogging.org

Melloni L, Molina C, Pena M, Torres D, Singer W, & Rodriguez E (2007). Synchronization of neural activity across cortical areas correlates with conscious perception. The Journal of neuroscience : the official journal of the Society for Neuroscience, 27 (11), 2858-65 PMID: 17360907

Uniquely conjoined twins

There was a posting a while back in Wiley Life Sciences Blog (here) about conjointed twins that share some parts of the brain, a unique condition. It is from the NYT original article by Susan Dominue and worth a read and a look at the video.

From the standpoint of understanding consciousness it has some interest. Anatomically the twins have fused skulls. Brain images reveal a connecting line between the two brains, a thalamic bridge. The thalamus is involved in sensory input, levels of brain activation and consciousness. There is a possibility that sensory input to one twin can cross over to the other twins. “One girl drinks, another girl feels it.” And yet despite a level of shared awareness, they appear to by very separate people with no real shared ‘self’.

It is a little more complicated because they have unusually short corpus callosum (the large tract of nerves connecting the left and right hemispheres) and the hemispheres are not symmetrical. One twin has an unusually small left hemisphere and the other an unusually small right one. This is a little like partially split brain individuals each with a different strengths and weaknesses that complement each other, being somewhat connected. So it is difficult to know what effect this has on each twin’s mental processing as well as their shared processing.

Sometimes they appear to be very separate, doing their own thing and ignoring the other. At other times they appear to be close to a single individual with a very complex body. It will be interesting to hear how they describe their lives when they are a little older and better able to make such descriptions.

Those doggy-people

Those doggy-people keep saying that dogs are special and they communicate with their dogs who have feelings similar to their own. Non-doggy-people just shake their heads. With a few caveats, I’m with the doogy-people.

People differ and so do dogs. Some dogs are unbelievably dumb or uninterested in their human companions or just uncooperative. At the other end of the scales, there are some very smart dogs, some very caring dogs and some dogs very willing to please. I just read a review of an article (Hecht 2012 Behavioral assessment and owner perceptions of behaviors associated with guilt in dogs. Appl. Anim. Behav. Sci.) about whether dogs show guilt, and kept thinking about a dog I had that was just plain sneaky, always playing games of deception. That dog would never let on that she had done something wrong. We might be able to guess that something was amiss if she was exceptionally friendly in a carefree manner. I would think, what is she hiding? Of course, she looked contrite when she was caught red-handed but that was just to shorten her scolding. Now, of course, I know that this description, if anything, makes the dog appear more human-like then a similar description of a dog that appears to show guilt. The point I am making is that dogs are a very mixed lot. I have known dogs that followed where I was pointing and dogs that didn’t. I have had dogs that understand many words and ones that only had a handful. Some dogs are jealous, some not, and so on.

But there are three reasons to assume (as much as is reasonable for any particular dog) that they have similar emotions, moods. signals etc. to ourselves. The first reason is that all mammals have similar brain types, hormones, sense organs and so on. We have to have a reasons to assume that they work differently from humans, not reasons to think they work the same. So if they look guilty than the starting point should be that they are feeling guilty. We might (and do) want to check that assumption, but it is only good physiology to start with the assumption of similarity.

The second reason we are reasonable in assuming dogs are similar to us is that we have lived together long enough to have developed over that time behaviours that work for both dogs and humans. We could have bred dogs that had the capacity to some small amount of guilt if they did not start out with any.

But the third reason is different. We humans are better at dealing with others if we use the system that comes naturally to us. We are social animals and have ways of understanding each other. It is simply easier to understand a dog if they view dogs as similar to people, than it is to view it as unlike anything else, a black box machine-like thingy. This idea was well said by a sheepdog trialer quoted in a post by Greg Downey on Paul Keil’s work (here). There is a lot in this post and it is well worth following the link to read the rest and look at the video clips.

In the demonstration for Paul, Damian (the trialer) intentionally gave Whiskey (the dog) a bad command, encouraging the dog to move in a way that was likely to cause the sheep to bolt out of control. After the sheep got loose, Damian described his interaction with Whiskey: I made the dog come around this way [clockwise around the mob of three sheep]. He said, ‘They’re gonna get away.’ He didn’t want to come. He said, ‘I think it’s a bad call.’ And I argued with him, and I said, ‘No. Come!’ And he said, ‘Nah nah… I tell you, they’re gonna go.’ And then he started to come, and the sheep started to go, and then he went, ‘See, I told ya’…

Of course, at no time did Whiskey actually speak to Damian. And Damian’s signals were whistles, shouts, and gestures, much simpler than the elaborate interpretation that Damian offered in his post-interaction analysis… Damian was explaining his perceptions of his dog’s thoughts as the two of them, together, interacted with three other animals, the sheep.

While Damian’s recollection was no doubt intentionally anthropomorphised, and possibly better elaborated than usual – giving the dog a voice – because of the sympathetic audience, the interaction that had occurred only minutes earlier was far more complex than a novice like Paul could recognise. Sure, Paul heard Damian give the command and witnessed the sheepdog’s momentary hesitation to follow, but he thought little about it; Damian’s description revealed a reciprocal exchange, a negotiation between human and dog based upon each one’s perceptions of the sheep and their spatial and emotional relations. Paul was simply not privy to a lot of the detail of their communication because he couldn’t see it. Whiskey was a far more sophisticated social agent then Paul could initially grasp…

The dog was not simply a tool, or merely obedient to a guiding human intelligence; on some level, Whiskey grasped what needed to be done, and Damian had come to count on the dog’s ability to herd, including the dog’s perception of how stressed and liable to flight the sheep were. The key to being an expert dog trialer, then, included the ability, not just to train a dog to herd, but to perceive the dog’s intentions and perceptions, and to anticipate the animal’s next move (as well as those of the sheep)…

Being an expert at interacting with dogs not only means a brain that’s better attuned to how dogs communicate; in fact, experts and non-experts, in most respects, are quite similar. Expertise means having behaviour patterns that include knowing where to search the animal’s body for information and greater tendency to ‘mentalise’ or impute motives to the animals (whether those projections are accurate is a separate question)…

That is, anthropomorophism may not be neurologically or biologically accurate, but it may be cognitively and practically useful, helping handlers to projectively scenario-build as they interact with their sheep and dogs (who are also engaged in their own cognitive forms of anticipation and negotiation with each other). Part of ‘thinking like a dog’ or a sheep may be inaccurately assuming that dogs and sheep are ‘thinking like an (admittedly odd or not terribly bright) four-legged human.’…Trialers would be the first to admit that the minds of sheep and dog are not the same as that of humans. They believe anthropomorphising the animals is a grave mistake. Most veteran trialers believe that the boundary between dogs and humans is wide and should not be blurred, or the dogs’ performance will suffer.

Still, even sheepdog trialers who are acutely aware of their dogs’ limits attribute internal mental states and dispositions such as ‘confidence,’ ‘beliefs,’ and ‘thoughts,’ not hesitating to project human-like cognitive events to their animals. If humans recruit the same socio-cognitive, neurological mechanisms they use with fellow humans to engage in the same kinds of interactions with other organisms, the overlap between folk psychological language for animals and humans should not be surprising. That is, if we’re using the same equipment to perceive a dog’s or sheep’s intentions as that we use to figure out what each other are thinking, anthropomorphizing is likely, even in old-school dog trialers who have strictly instrumental relations with their dogs and sheep, much more so than most people with their companion animals.

Of course, if folk psychological language suggests we’re using the same cognitive or neurological mechanisms we use for reading humans, we would expect a degree of anthropomorphic ‘overshoot.’ Cognitive overlap in the ability to perceive animal intentionality would likely lead us to over-estimate the nonhuman animal’s capacities, over-anthropomorphising their cognition.

Sheepdog trials and that ‘man-sheep-dog’ configuration remind us that humans do not face other animals alone. Let’s not forget the dogs. As Shipman has pointed out, dogs are special. When our ancestors and the ancestors of dogs came into contact, two species with extraordinary social skills, and surprisingly similar pack hunting strategies, began a long relationship that arguably shaped the evolution of both over the next thousands of years. … Dogs may be ‘overshooting’ their attribution of dog-like responses when they interact with us. … Do dogs bring their own canine-morphistic tendencies to relationships with humans and other animals?

Whether their ‘readings’ of the animals’ states are accurate is less important than the fact that both species communicate in predictable, useful ways so that they can work together, anticipate each others’ actions, and live in stable inter-species communities.

But I have to say that if a model works well and is useful, it is unlikely to be completely wrong. When anthropomorphism works very well (as it does with dogs) then it is probably somewhat accurate. I am very inclined to view my dog as a conscious animal with similar emotions and low-voltage but similar thinker.

Affordance competition

Since the Libet experiment (and many following it), it has been difficult to assume that conscious intention causes motor action as the action decision is chronologically ahead of the conscious feeling of intention. But there was some who thought that the vetoing of a decision was still possibly caused by conscious intention – the ‘free-wont’ idea. A recent paper (citation below) looks at the mechanism of switching motor plans and makes ‘free-wont’ less attractive.

(The) “affordance competition” hypothesis stands in contrast to the classical serial model, in which decisions are made in higher cognitive centers and the resulting choice passed down to the sensorimotor system for execution. Instead, it suggests that decisions are determined when a competition between actions is resolved within the sensorimotor system – e.g., for reaching, within the fronto-parietal cortex and associated corticostriatal loops. This means that although the biases that influence the decision may come from many sources, including the activity of higher cognitive regions, it is in the sensorimotor system that the final decision is taken. … the same “forward models” useful for predicting the consequences of motor commands may also play a role in selecting the actions themselves by biasing activity in sensorimotor cortices. … The affordance competition hypothesis predicts that if we present a monkey with multiple reaching options associated with different rewards, neural activity in Pmd (dorsal premotor cortex) will be modulated by the relative value of those rewards. … However, the hypothesis also makes a complementary prediction: that the same cells involved in selecting the initial action will continue to be involved in adjusting and even switching between actions during overt behavior. In other words, if the environment changes and old opportunities are lost or new ones become available, the same integrated selection and sensorimotor guidance system should reflect the switch of the plan.

 

The question investigated was whether the very same cells that steer the initial decision will continue with their activities if an animal changes its mind and guide the new action.

It is plausible that once a decision is made and an action is launched toward a given target, the decision-related cells fall silent while a separate circuit becomes responsible for guiding movement toward the selected target. The results presented here suggest that this is not the case. We found that the very same PMd (dorsal premotor cortex) cells previously shown to reflect relative value during a delay period continue to update their activity to reflect when the monkey changes its plan during situations in which a previously selected action becomes unavailable. This argues against the distinction between regions responsible for choosing an action and those responsible for its guidance through on-line feedback, and in favor of the hypothesis that decisions emerge through a competition within the same circuit that guides movement execution. … This suggests a view whereby sensory information continuously flows into the motor system, as opposed to a view of separate computational stages involved in canceling one motor program and computing a new one.

 

Here is the abstract which outlines the method as well as the results:

Previous studies have shown that neural activity in primate dorsal premotor cortex (PMd) can simultaneously represent multiple potential movement plans, and that activity related to these movement options is modulated by their relative subjective desirability. These findings support the hypothesis that decisions about actions are made through a competition within the same circuits that guide the actions themselves. This hypothesis further predicts that the very same cells that guide initial decisions will continue to update their activities if an animal changes its mind. For example, if a previously selected movement option suddenly becomes unavailable, the correction will be performed by the same cells that selected the initial movement, as opposed to some different group of cells responsible for online guidance. We tested this prediction by recording neural activity in the PMd of a monkey performing an instructed-delay reach selection task. In the task, two targets were simultaneously presented and their border styles indicated whether each would be worth 1, 2, or 3 juice drops. In a random subset of trials (FREE), the monkey was allowed a choice while in the remaining trials (FORCED) one of the targets disappeared at the time of the GO signal. In FORCED-LOW trials the monkey was forced to move to the less valuable target and started moving either toward the new target (Direct) or toward the target that vanished and then curved to reach the remaining one (Curved). Prior to the GO signal, PMd activity clearly reflected the monkey’s subjective preference, predicting his choices in FREE trials even with equally valued options. In FORCED-LOW trials, PMd activity reflected the switch of the monkey’s plan as early as 100 ms after the GO signal, well before movement onset (MO). This confirms that the activity is not related to feedback from the movement itself, and suggests that PMd continues to participate in action selection even when the animal changes its mind on-line. These findings werereproduced by a computational model suggesting that switches between action plans can be explained by the same competition process responsible for initial decisions.

 

This doesn’t rule out ‘free-wont’ but it certainly weakens it.

 

ResearchBlogging.org

Pastor-Bernier A, Trembley E, & Cisek P (2012). Dorsal premotor cortex is involved in switching motor plans Frontiers in Neuroengineering, 5

Forcing attention

There is an idea that EB Bolles argued for in his blog, Babel’s Dawn (here), and his book by the same name. It is that words are in effect pointers than force the listener’s attention to a topic or element of a topic. So if I say ‘flag’ and there is a flag near by, your attention will shift to that flag, and, if there is no flag in sight, your attention with shift to the concept of flag in your mind. The shift would be automatic. Words steer attention and force it to find what matches the word; the meaning of a word is the collection of concepts that it can force into attention. This idea depends on whether attention can be steered and the usual example used the illustrate the effect is the way we follow a pointing finger or another person’ gaze.

 

A recent paper (see citation) confirms that both gaze and arrows can steer attention. Here is what they did:

…we aimed at testing a strong definition of resistance to suppression for orienting of attention elicited by these two cues. In five experiments, participants were informed with 100% certainty about the future location of a target they had to react to by presentation of either a direction word at the beginning of each trial or instructions at the beginning of each block. Gaze and arrows were presented before the target as uninformative distractors irrelevant for the task. The results showed similar patterns for gaze and arrows—namely, an interference effect when the distractors were incongruent with the upcoming target location. This suggests that the orienting of attention mediated by gaze and arrows can be considered as strongly automatic.

 

The finding that the information conveyed by distractors interfered with the task indicates that orienting of attention mediated by both gaze and arrows resists suppression and can be defined as strongly automatic. Indeed, even though participants were informed with 100% certainty about the upcoming target location, and, thus, they were motivated to voluntarily attend to that location, results showed that they could not ignore the information conveyed by the distractors.

 

The authors do not seem to view the arrow as a stand-in for pointing and therefore likely to be a similar cue to gaze – one that we are innately supplied with. My opinion is that it is likely to be closely related to pointing. Humans and some animals do follow pointing at an early age.

 

However, it is important to point out that the similar behavioural effect obtained for gaze and arrows—namely, the elicitation of an automatic attention shift—does not necessarily imply that the underlying processes are the same for these two cue types. Indeed, arrows are able to elicit an automatic attention shift probably because they are a well-learned symbol, which conveys a strong spatial information that is reinforced every day, for instance by means of road signs. On the contrary, gaze is likely to trigger an automatic attention orienting because it may represent a special cue characterized by a strong biological significance given its relevance in everyday life, and, for such reasons, humans would have developed a reflexive attention shift in response to the view of an averted gaze that would also be supported by a dedicated neural circuit. Moreover, the presence of gaze-mediated orienting of attention in both new-borns as young as 2 days old and several species of nonhuman primates suggests that this phenomenon can be defined as innate, thus reinforcing the special nature of gaze as compared to other cue types.

 

It is not easy to see how communication is possible unless there is some sort of ‘steering attention to x’ mechanism so that one brain could influence the events in another brain. That is after all what communication is. Studying the control of attention is important to many aspects of neuroscience (preception, consciousness, communication at least).

 

ResearchBlogging.org

Galfano G., Dalmaso M., Marzoli D., Pavan G., Coricelli C., & Castelli L. (2012). Eye gaze cannot be ignored (but neither can arrows) The Quarterly Journal of Experimental Psychology

Memory associations

ScienceDaily has an item (here) on a U of Pennsylvania press release about decoded neural patterns of memory recall. The research was done by M. Kahana, J. Manning and others. They took advantage of the opportunity presented by epileptic patients with implanted electrodes allowing experimentation on their brains during the wait for surgery. Recordings were made from the electrodes while the patients studied 15 words and than repeated them in any order.

The researchers examined the brain recordings as the participants studied each word to home in on signals in the participant’ brains that reflected the meanings of the words. About a second before the participants recalled each word, these same “meaning signals” that were identified during the study phase were spontaneously reactivated in the participants’ brains.

Because the participants were not seeing, hearing or speaking any words at the times these patterns were reactivated, the researchers could be sure they were observing the neural signatures of the participants’ self-generated, internal thoughts.

The subject’s patterns were individual. But there was a similarity between the how much patterns for different words overlapped and how close words were in order of their recall. The research implies that there is a neural signature in organizing of learned information by meaning.

“In addition to looking at memories organized by time, as in our previous study, or by meaning, as in our current study, one could use our technique to identify neural signatures of how individuals organize learned information according to appearance, size, texture, sound, taste, location or any other measurable property,” Manning said.