Measuring consciousness -how an anesthetic puts us to sleep.

Ferrarelli et al. show what is happening when we are zonked out by an anesthetic like the benzodiazepine midazolam. They use an array of EEG electrodes on the head to measure how much the activities of different areas of the cortex are coordinated with each other when a magnetic pulse is applied to stir things up (transcranial magnetic stimulation, or TMS). When we are awake TMS triggers responses in multiple cortical areas lasting for more than 300 ms, during midazolam-induced loss of consciousness, TMS-evoked activity is shorter and more local, i.e. areas of the cortex stop talking to each other. Here is their abstract:

By employing transcranial magnetic stimulation (TMS) in combination with high-density electroencephalography (EEG), we recently reported that cortical effective connectivity is disrupted during early non-rapid eye movement (NREM) sleep. This is a time when subjects, if awakened, may report little or no conscious content. We hypothesized that a similar breakdown of cortical effective connectivity may underlie loss of consciousness (LOC) induced by pharmacologic agents. Here, we tested this hypothesis by comparing EEG responses to TMS during wakefulness and LOC induced by the benzodiazepine midazolam. Unlike spontaneous sleep states, a subject’s level of vigilance can be monitored repeatedly during pharmacological LOC. We found that, unlike during wakefulness, wherein TMS triggered responses in multiple cortical areas lasting for >300 ms, during midazolam-induced LOC, TMS-evoked activity was local and of shorter duration. Furthermore, a measure of the propagation of evoked cortical currents (significant current scattering, SCS) could reliably discriminate between consciousness and LOC. These results resemble those observed in early NREM sleep and suggest that a breakdown of cortical effective connectivity may be a common feature of conditions characterized by LOC. Moreover, these results suggest that it might be possible to use TMS-EEG to assess consciousness during anesthesia and in pathological conditions, such as coma, vegetative state, and minimally conscious state.

Are kids overmedicated?

Zuger reviews a book by Judith Warner on a topic that I and many others have had a knee jerk reflex type opinion on:  "Yes, of course kids are overmedicated by lazy parents and pill popping psychologists."  Warner began her study with that attitude, intending to prove her point,  and found quite the opposite.   She:

...sallied forth to interview all the pushy parents, irresponsible doctors and overmedicated children she could find — and lo, she could barely find any. After several years of dead ends, missed deadlines and worried soul-searching, she was forced to reconsider her premise and start all over again.

“A couple of simple truths have become clear,” she writes with the passion of a new convert. “That the suffering of children with mental health issues (and their parents) is very real. That almost no parent takes the issue of psychiatric diagnosis lightly or rushes to ‘drug’ his or her child; and that responsible child psychiatrists don’t, either. And that many children’s lives are essentially saved by medication, particularly when it’s combined with evidence-based forms of therapy.”

The power of touch.

I've been meaning to point to an interesting article by Benedict Carey on our voluntary momentary touches that can - whether an exuberant high five, a warm hand on the shoulder, or a creepy touch to the arm — communicate an even wider range of emotion than gestures or expressions, and sometimes do so more quickly and accurately than words. He focuses on work of Dacher Keltner, Hertenstein, and collaborators, the subject of previous posts (PDF here, also, enter Keltner in the search box in the left column). In their experiments volunteers tried to communicate a list of emotions by touching a blindfolded stranger. The participants were able to communicate eight distinct emotions, from gratitude to disgust to love, some with about 70 percent accuracy. Here is their abstract:

The study of emotional communication has focused predominantly on the facial and vocal channels but has ignored the tactile channel. Participants in the current study were allowed to touch an unacquainted partner on the whole body to communicate distinct emotions. Of interest was how accurately the person being touched decoded the intended emotions without seeing the tactile stimulation. The data indicated that anger, fear, disgust, love, gratitude, and sympathy were decoded at greater than chance levels, as well as happiness and sadness, 2 emotions that have not been shown to be communicated by touch to date. Moreover, fine-grained coding documented specific touch behaviors associated with different emotions.

A forthcoming publication from Kraus, Huang, and Keltner finds that, with a few exceptions, good basketball teams tended to be touchier than bad ones. Another slightly edited clip:

If a high five or an equivalent can in fact enhance performance, on the field or in the office, that may be because it reduces stress. A warm touch seems to set off the release of oxytocin, a hormone that helps create a sensation of trust, and to reduce levels of the stress hormone cortisol...In the brain, prefrontal areas, which help regulate emotion, can relax, freeing them for another of their primary purposes: problem solving. In effect, the body interprets a supportive touch as “I’ll share the load.”...“We think that humans build relationships precisely for this reason, to distribute problem solving across brains,” said James A. Coan, a a psychologist at the University of Virginia. “We are wired to literally share the processing load, and this is the signal we’re getting when we receive support through touch.”

The same is certainly true of partnerships, and especially the romantic kind, psychologists say. In a recent experiment, researchers led by Christopher Oveis of Harvard conducted five-minute interviews with 69 couples, prompting each pair to discuss difficult periods in their relationship...The investigators scored the frequency and length of touching that each couple, seated side by side, engaged in... "it looks so far like the couples who touch more are reporting more satisfaction in the relationship,” he said.  Again, it’s not clear which came first, the touching or the satisfaction. But in romantic relationships, one has been known to lead to the other. Or at least, so the anecdotal evidence suggests.

Food and Flying

An interesting tidbit from the Random Samples section of the 19 Feb. issue of Science Magazine:

German scientists have figured out why tomato juice tastes better aboard an airplane than on the ground (and coffee tastes worse). Low atmospheric pressure dampens the experience of sweet and salty tastes whereas sour comes through unchanged and bitter is slightly intensified, says flavor chemist Andrea Burdack-Freitag of the Frauenhofer Institute for Building Physics in Holzkirchen.

She and her colleagues asked 30 taste testers to rate their perceptions of different foods and wine while sitting in a partial Airbus A310 in a chamber with adjustable pressure. At ground pressures, tasters perceived tomato juice as musty, but at a low pressure typical in flight they found it fruitier, with cool notes. The complex aromas picked up by the nose that give coffee its flavor were barely perceived at low pressure, unmasking caffeine's bitterness, Burdack-Freitag says. Lufthansa's catering arm, which sponsored the study, wants to use the data to improve its menus.

Damage to our amygdala can eliminate monetary loss aversion

Here is an interesting open access article from Ralph Adolphs and his colleagues:

Losses are a possibility in many risky decisions, and organisms have evolved mechanisms to evaluate and avoid them. Laboratory and field evidence suggests that people often avoid risks with losses even when they might earn a substantially larger gain, a behavioral preference termed “loss aversion.” The cautionary brake on behavior known to rely on the amygdala is a plausible candidate mechanism for loss aversion, yet evidence for this idea has so far not been found. We studied two rare individuals with focal bilateral amygdala lesions using a series of experimental economics tasks. To measure individual sensitivity to financial losses we asked participants to play a variety of monetary gambles with possible gains and losses. Although both participants retained a normal ability to respond to changes in the gambles’ expected value and risk, they showed a dramatic reduction in loss aversion compared to matched controls. The findings suggest that the amygdala plays a key role in generating loss aversion by inhibiting actions with potentially deleterious outcomes.

Oxytocin may improve autism

I have done a large number of posts on behavioral effects of oxytocin, the 'trust hormone', notably in human studies that use an oxytocin inhaler (enter oxytocin in the blog search box in the left column to display them).  Recent studies are now suggesting that when some autistic people (who have difficulty interacting with others) inhale oxytocin, they began looking at people in the eye and recognizing social concepts like fairness in a computer game.

Behavioral Addictions in the proposed DSM-V

I am increasingly amazed at the creeping "pathologicalization" of behaviors that vary a bit from the 'normal'.  Almost any repetitive activity or habit could be construed as a behavioral addition (Tiger Wood's golf and sex?).  I might well be considered an alcoholic sociopathic sex addict by some, given my one a day knockout happy hour drink, my extremely active libido, and my ability to observe the generation of my emotional and social behaviors and halt or detach from them when necessary. I though this article by Constance Holden had some interesting chunks, which I pass on here (see also the related previous post yesterday on the Bonkers institute):

"...proposed revisions for the American Psychiatric Association's (APA's) Diagnostic and Statistical Manual of Mental Disorders (DSM) include for the first time "behavioral addictions"—a change some say is long overdue and others say is still premature...

"Sex addiction" has received a lot of press lately, but O'Brien [University of Pennsylvania, chair of the addictions work group for DSM-V] says his work group found "no scientific evidence" that sex qualifies. APA psychiatrist Darrel Regier, co-chair of the DSM task force, says "it's not clear that reward circuitry is operative in the same way as in addictive areas." Nonetheless, a near equivalent may make it into the sexual disorders section of DSM: That work group is proposing a controversial new diagnosis of "hypersexual disorder."

The DSM teams have also tussled with the often-blurry line between addictions and compulsions. "I used to think [addictions] overlapped with OCD [obsessive-compulsive disorder]," says O'Brien. But new data from both brain-imaging and treatment studies suggest "more dissimilarities than similarities."

In another major change, O'Brien's group recommends dropping categories of "abuse" and "dependence" and labeling all problems major and minor as substance "use disorders" (or "disordered gambling"). Since the late 1980s, says O'Brien, "numerous large population studies" have shown there's no "breakpoint" where "abuse" becomes something more serious. He also says the term "dependence" only implies physiological dependence, which is not the same as the psychological obsession of addiction.

Some longtime addiction researchers, such as psychiatrist Victor Hesselbrock of the University of Connecticut, Farmington, have qualms about the direction DSM is moving. Hesselbrock believes behavioral addictions are dicey territory and prefers to limit the term "addiction" to substances, which are "pathogens we can identify." He also objects to fusing all drinking problems into "alcohol use disorder." Hesselbrock says he and others think there are proven subcategories of alcoholism that would aid both in treatment and discovering causes. "When you do a one-size-fits-all type of classification system," he says, "that will fit a lot of people but not so well."

Our thalamus goes to sleep before our cerebral cortex

Magnin et al. have recorded thalamic and cortical activities simultaneously in epileptic patients chronically implanted with intracerebral electrodes to address the issue of when these two regions of the brain go to sleep. (The thalamus is the main gateway through which information from our bodies flows to the cortex.) They find, contrary to the common view, that the thalamus deactivates well before the cortex during sleep onset, leaving the cortex to spin its stories without input from the world during a hypnagogic or half-awake state during which illusions or inspirations sometimes occur, giving us the impression that it is taking us longer to get to sleep than is actually the case. Here is their abstract:

Thalamic and cortical activities are assumed to be time-locked throughout all vigilance states. Using simultaneous intracortical and intrathalamic recordings, we demonstrate here that the thalamic deactivation occurring at sleep onset most often precedes that of the cortex by several minutes, whereas reactivation of both structures during awakening is synchronized. Delays between thalamus and cortex deactivations can vary from one subject to another when a similar cortical region is considered. In addition, heterogeneity in activity levels throughout the cortical mantle is larger than previously thought during the descent into sleep. Thus, asynchronous thalamo-cortical deactivation while falling asleep probably explains the production of hypnagogic hallucinations by a still-activated cortex and the common self-overestimation of the time needed to fall asleep.

Depression's Upside

Jonah Lehrer (a really bright guy, author of "How We Decide", "Proust was a Neuroscientist", and the blog "The Frontal Cortex") has made his first New York Times Magazine contribution, an excellent article on depression that focuses on work of Andrews and Thomson who suggest that depression is a evolved behavior that has the function of removing us from normal daily behaviors to focus on and hopefully solve a pressing life issue.  They describe their model as the "analytic-rumination hypothesis." A few clips from the article:

Several studies found an increase in brain activity (as measured indirectly by blood flow) in the VLPFC of depressed patients. Most recently, a paper to be published next month by neuroscientists in China found a spike in “functional connectivity” between the lateral prefrontal cortex and other parts of the brain in depressed patients, with more severe depressions leading to more prefrontal activity. One explanation for this finding is that the hyperactive VLPFC underlies rumination, allowing people to stay focused on their problem...the reliance on the VLPFC doesn’t just lead us to fixate on our depressing situation; it also leads to an extremely analytical style of thinking. That’s because rumination is largely rooted in working memory, a kind of mental scratchpad that allows us to “work” with all the information stuck in consciousness. When people rely on working memory — and it doesn’t matter if they’re doing long division or contemplating a relationship gone wrong — they tend to think in a more deliberate fashion, breaking down their complex problems into their simpler parts.

The bad news is that this deliberate thought process is slow, tiresome and prone to distraction; the prefrontal cortex soon grows exhausted and gives out. Andrews and Thomson see depression as a way of bolstering our feeble analytical skills, making it easier to pay continuous attention to a difficult dilemma. The downcast mood and activation of the VLPFC are part of a “coordinated system” that, Andrews and Thomson say, exists “for the specific purpose of effectively analyzing the complex life problem that triggered the depression.” If depression didn’t exist — if we didn’t react to stress and trauma with endless ruminations — then we would be less likely to solve our predicaments. Wisdom isn’t cheap, and we pay for it with pain.

....the analytic-rumination hypothesis is merely the latest attempt to explain the prevalence of depression. There is, for example, the “plea for help” theory, which suggests that depression is a way of eliciting assistance from loved ones. There’s also the “signal of defeat” hypothesis, which argues that feelings of despair after a loss in social status help prevent unnecessary attacks; we’re too busy sulking to fight back. And then there’s “depressive realism”: several studies have found that people with depression have a more accurate view of reality and are better at predicting future outcomes. While each of these speculations has scientific support, none are sufficient to explain an illness that afflicts so many people. The moral, Nesse says, is that sadness, like happiness, has many functions.

To say that depression can be useful doesn't mean it is always going to be useful. While it might explain patients reacting to an acute stressor, it can’t account for those whose suffering has no discernible cause or whose sadness refuses to lift for years at a time.

In the last section of the article Lehrer notes a number of studies indicating a correlation of depression with better artistic creativity and improved analytical abilities.

Asymptomatic Depression - hidden disease and untapped market

The distinguished Dr. Methodius Bonkers has emailed me to point out his institute's most recent study.  It is a hoot.

A Mozart Presto

Here is another of the rehearsal recordings we make to critique, to be eventually replaced by a final version. It is a run through of the Presto (last movement) of Mozart's Piano Sonata for 4-hands, K. 358. I'm playing base, David Goldberger is playing treble.

Evidence for a geometric brain module suggested by William's syndrome defect

Context from the introduction by Lakusta et al.

When rats, human toddlers, or adults are disoriented in a chamber, they search for targets using geometric properties of the layout, often ignoring quite salient nongeometric cues. This pattern has led scientists to hypothesize that reorientation in animals (including humans) is guided by a cognitive module that engages geometric properties of layouts such as the lengths of surfaces, the angles of their intersections, and geometric sense (i.e., “left-” and “right-ness”), but does not engage nongeometric information such as surface color.

The authors find that geometric reorientation abilities are specifically impaired in Williams Syndrome patients. (Williams syndrome results from a microdeletion in chromosome 7q11.23. People with the syndrome have mild to moderate retardation and highly selective but severe impairment in a range of spatial tasks that normally engage parietal and other dorsal stream functions of the brain.)  Here is their abstract:

The capacity to reorient in one’s environment is a fundamental part of the spatial cognitive systems of both humans and nonhuman species. Abundant literature has shown that human adults and toddlers, rats, chicks, and fish accomplish reorientation through the construction and use of geometric representations of surrounding layouts, including the lengths of surfaces and their intersection. Does the development of this reorientation system rely on specific genes and their action in brain development? We tested reorientation in individuals who have Williams syndrome (WS), a genetic disorder that results in abnormalities of hippocampal and parietal areas of the brain known to be involved in reorientation. We found that in a rectangular chamber devoid of surface feature information, WS individuals do not use the geometry of the chamber to reorient, failing to find a hidden object. The failure among people with WS cannot be explained by more general deficits in visual-spatial working memory, as the same individuals performed at ceiling in a similar task in which they were not disoriented. We also found that performance among people with WS improves in a rectangular chamber with one blue wall, suggesting that some individuals with WS can use the blue wall feature to locate the hidden object. These results show that the geometric system used for reorientation in humans can be selectively damaged by specific genetic and neural abnormalities in humans.

Human pheromones - androstenol activates hypothalamus in women.

There is continuing debate over whether, and to what extent, we humans (like other mammals) might use body odors secreted from our skin in signaling sexual attraction, aggression, submission, etc.  Several progesterone derivatives have been shown to activate regions of the thalamus and hypothalamus, and the activations are differentiated with respect to sex and sexual orientation of the smeller in relation to the respective compounds.   Slavic et al. asked whether compounds actually released by our bodies have pheromone properties, and focused on highly volatile androstenol, which is found (primarily in males), in sweat, urine, plasma and saliva. They found that smelling androstenol (unlike several common odors) causes activation of a portion of the hypothalamus in women that animal data suggests mediates pheromone triggered mating behavior. (The article is open access, and you can see the brain imaging data there.)

Reward centers in men activated by optimal hip-to-waist ratio in women

Observations from Platek and Singh add to the evolutionary psychologists' discussion of determinants of men's sexual preferences. They take male preference for lower hip waist ratio in females (as indicative of reproductive quality) to be culturally universal, but I recall debate on this point, and indeed find that debate covered by cited references (17,18) at the end of the article. Their core observation is that when men view photographs of women after and before plastic surgery to achieve an optimal (~0.7) waist to hip ratio (with redistributed body fat but relatively unaffected body mass index), an increase in activation of brain rewards centers can be observed. They suggest their observations "are the first description of a neural correlate implicating waist to hip ratio as a putative honest biological signal of female reproductive viability and its effects on men's neurological processing."

Is the internet making us smarter or dumber?

During happy hour at my local watering hole, I frequently pull out my iPhone and do a bit of random web cruising. Several nights ago this yielded this piece on effects of internet use on our intelligence, suggesting extensive internet use makes us different, but not dumb. The article cites a Pew Study reporting, contra an influential article by Nicholas Carr, that 76 percent of the respondents said they agree that by 2020, "people’s use of the Internet has enhanced human intelligence; as people are allowed unprecedented access to more information, they become smarter and make better choices. The article also relays the opinions of a number of other futurists.

Universal nonverbal vocal communication of negative, but not positive, emotions.

Here is a fascinating open access article well worth having a look at:

Emotional signals are crucial for sharing important information, with conspecifics, for example, to warn humans of danger. Humans use a range of different cues to communicate to others how they feel, including facial, vocal, and gestural signals. We examined the recognition of nonverbal emotional vocalizations, such as screams and laughs, across two dramatically different cultural groups. Western participants were compared to individuals from remote, culturally isolated Namibian villages. Vocalizations communicating the so-called “basic emotions” (anger, disgust, fear, joy, sadness, and surprise) were bidirectionally recognized. In contrast, a set of additional emotions was only recognized within, but not across, cultural boundaries. Our findings indicate that a number of primarily negative emotions have vocalizations that can be recognized across cultures, while most positive emotions are communicated with culture-specific signals.

Holy surgery and the spiritual brain.

Over the past several years I've done a number of posts on brain correlates of spirituality, in particular work on lesions or temporal lobe seizures that induce mystical or spiritual states (click the religion topic in the left column to find them). Urgesi et al. have now done a clinical study on selective cortical lesions that modulate human self transcendence. They 88 brain cancer patients to fill out a widely used personality questionnaire before and after surgery to remove their tumors. One section of the test measured "self transcendence." It asked respondents, for example, about their tendency to become so absorbed in an activity that they lose track of time and place and whether they feel a strong spiritual connection with other people or with nature. They found that selective damage to left and right inferior posterior parietal regions induced a specific increase of self-transcendence. Other studies have found that some of the same regions become active during prayer and meditation. These posterior parietal brain regions have been implicated in providing awareness of the body's position and location in space.

Figure - Lesion Correlates of Increased and Decreased Self Transcendence. The authors found two clusters of voxels located in the left inferior parietal lobe (L-IPL; A) and in the right angular gyrus (R-AG; B) whose damage was associated with a significant ST increase.

The 'cutaneous rabbit' hops outside of the body!

A well known demonstration of how our brain makes assumptions about what is happening 'out there' on the basis of very limited input is the 'Cutaneous Rabbit' demonstration. If rapid sequential taps are delivered to two points on our skin, we also feel sequential taps at points intermediate between the two, as if a small rabbit were hopping along our skin. The assumption has been that this illusion is link to our somatotopic sensory cortex, which continuously maps the skin surface. Miyazaki et al. show that this illusion can be moved to an external object - a stick held between our left and right index fingers. Here is the abstract from their open access article:

Rapid sequential taps delivered first to one location and then to another on the skin create the somatosensory illusion that the tapping is occurring at intermediate locations between the actual stimulus sites, as if a small rabbit were hopping along the skin from the first site to the second (called the "cutaneous rabbit"). Previous behavioral studies have attributed this illusion to the early unimodal somatosensory body map. A functional magnetic resonance imaging study recently confirmed the association of the illusion with somatotopic activity in the primary somatosensory cortex. Thus, the cutaneous rabbit illusion has been confined to one's own body. In the present paper, however, we show that the cutaneous rabbit can "hop out of the body" onto an external object held by the subject. We delivered rapid sequential taps to the left and right index fingers. When the subjects held a stick such that it was laid across the tips of their index fingers and received the taps via the stick, they reported sensing the illusory taps in the space between the actual stimulus locations (i.e., along the stick). This suggests that the cutaneous rabbit effect involves not only the intrinsic somatotopic representation but also the representation of the extended body schema that results from body–object interactions.

Some friday morning Mozart

Working with retired professional pianist David Goldberger, I'm preparing for a 4-hands recital on Sunday, March 7 in Fort Lauderdale. I decided to make a few rehearsal recordings, to be eventually replaced by a final version. The video below is of a palatable, but we think much less than optimal, run through of the Allegro (first movement) of Mozart's Piano Sonata for 4-hands, K. 358. We will also be doing the Schubert Fantasy for 4-hands.

Effect of socioeconomic status on increase in stress hormones over time.

A sobering account from Chen et al.:

Disparities by socioeconomic status (SES) are seen for numerous mental and physical illnesses, and yet understanding of the pathways to health disparities is limited. We tested whether SES alters longitudinal trajectories of cortisol output and what types of psychosocial factors could account for these links. Fifty healthy children collected saliva samples (four times per day for 2 days) at 6-month intervals for 2 years. At baseline, families were interviewed about SES and psychosocial factors. Lower-SES children displayed greater 2-year increases in daily cortisol output compared with higher-SES children. These effects were partially mediated by children’s perceptions of threat and by family chaos. These findings may help explain, and provide some first steps toward ameliorating, low-SES children’s vulnerability to health problems later in life by identifying the tendency to perceive threat in ambiguous situations and experiences of chaos as factors that link low SES to 2-year hormonal trajectories.