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The case of Tatiana And Krista Hogan

17 Nov

Tatiana And Krista Hogan are co-joined twins who share brain tissue. According to Wikipedia they are joined at the thalamus, brain structure that projects sensory information onto the cerebral cortex. According to a post on the CBC website:

Neurological studies have stunned the doctors. Tatiana can see out of both of Krista’s eyes, while Krista can only see out of one of Tatiana’s. They also share the senses of touch and taste and the connection even extends to motor control. Tatiana controls 3 arms and a leg, while Krista controls 3 legs and an arm.
Amazingly, the girls say they also know one another’s thoughts without needing to speak. “We talk in our heads” is how they describe it.

The CBC has produced a documentary about the twins, unfortunately not yet available in the U.S.

Psychiatric Disorders and Brain pH

27 Oct

From Scientific American:

There were earlier hints of the acid-disorder link: studies that directly measured pH—a metric of how acidic or basic something is—in dozens of postmortem human brains revealed lower pH (higher acidity) in patients with schizophrenia and bipolar disorder. Multiple studies in the past few decades have found that when people with panic disorder are exposed to air with a higher than normal concentration of carbon dioxide—which can combine with water in the body to form carbonic acid—they are more likely to experience panic attacks than healthy individuals are. Other research has revealed that the brains of people with panic disorder produce elevated levels of lactate, an acidic source of fuel that is constantly generated and consumed in the energy-hungry brain.

If these findings hold up, there may be new avenues for treatment.


“Tympanic Membrane Temperature and Hemispheric Cognitive Style”

4 Oct

I am a co-author on this paper, just published in The Journal of Genetic Psychology:

The authors tested the hypothesis that there is a correlation between hemispheric cognitive style and ear temperature. A sample of 100 participants completed a measure of hemispheric cognitive style, the Hemispheric Consensus Prediction Profile. Ear temperatures were taken in 2 sessions, 2 times for each ear at each session. Average left ear temperature was subtracted from average right ear temperature as an index of dominant temperature. Only 56 of the participants showed a stable dominant ear temperature. For these 56 participants, there was a statistically significant positive correlation between scores on the Hemispheric Consensus Prediction Profile and tympanic member temperature (Spearman’s ρ =.29, 95% CI [.04,.51]). Individuals with a left hemispheric cognitive style tended to have a warmer left tympanic membrane temperature while those with a right hemispheric cognitive style tended to have a warmer right tympanic membrane temperature. Tympanic membrane temperatures are easily obtained using inexpensive and noninvasive technology. The relationship suggested by these findings may open new opportunities for the study of cerebral asymmetry.

The Higher Efficiency of the Bilingual Brain

2 Jun

A paper in The Journal of Neurolinguistics: “Interference Control at the Response Level: Functional Networks Reveal Higher Efficiency in the Bilingual Brain.” Here is the abstract:

The bilingual advantage in interference control tasks has been studied with the Simon task, among others. The mixed evidence from the existing studies has led to contradictions in the literature regarding the bilingual advantage. Moreover, fMRI evidence on the neural basis of interference control mechanisms with the Simon task is limited. Previous work by our team showed that equivalent performance on the Simon task was associated with different activation maps in elderly bilinguals and monolinguals. This study aims to provide a more in-depth perspective on the neural bases of performance on the Simon task in elderly bilinguals and monolinguals, by adopting a network perspective for the functional connectivity analysis. A node-by-node analysis led to the identification of the specific topology that characterized the bilingual and monolingual functional networks and the degree of connectivity between each node across groups. Results showed greater connectivity in bilinguals in the inferior temporal sulcus, which plays a role in visuospatial processing. On the other hand, in monolinguals, brain areas involved in visual, motor, executive functions and interference control were more connected to resolve the same task. In other words, in comparison to the monolingual brain, the bilingual brain resolves visuospatial interference economically, by allocating fewer and more clustered regions. These results demonstrate a larger global efficiency in task performance in bilinguals as compared to monolinguals. Also, the provided evidence filters out the task-specific so-called bilingual advantage discussed in the literature and posits that bilinguals are strategically more efficient in a given performance than monolinguals, thus enhancing our understanding of successful aging.

You can read about the Simon Task here.


High Blood Pressure and Dementia

21 Apr

Dr. Greger has the details:

Crows Outperform Pigeons and Primates in Learning a Basic Concept

24 Feb

A paper just published in Psychological Science:

Corvids (birds of the family Corvidae) display intelligent behavior previously ascribed only to primates, but such feats are not directly comparable across species. To make direct species comparisons, we used a same/different task in the laboratory to assess abstract-concept learning in black-billed magpies (Pica hudsonia). Concept learning was tested with novel pictures after training. Concept learning improved with training-set size, and test accuracy eventually matched training accuracy—full concept learning—with a 128-picture set; this magpie performance was equivalent to that of Clark’s nutcrackers (a species of corvid) and monkeys (rhesus, capuchin) and better than that of pigeons. Even with an initial 8-item picture set, both corvid species showed partial concept learning, outperforming both monkeys and pigeons. Similar corvid performance refutes the hypothesis that nutcrackers’ prolific cache-location memory accounts for their superior concept learning, because magpies rely less on caching. That corvids with “primitive” neural architectures evolved to equal primates in full concept learning and even to outperform them on the initial 8-item picture test is a testament to the shared (convergent) survival importance of abstract-concept learning.

The article’s conclusion contains this passage:

So, how did the apparently primitive bird brain that evolved from dinosaurs become competitive with, and even initially outperform, the abilities of what has been considered a more elaborate primate brain to perform abstract-concept learning, which involves thoughts and processes considered to be of the highest cognitive order? The answer most certainly lies in evolution itself, a multimillion-year process. Environmental pressures (social and otherwise) undoubtedly selected for and shaped these different neural architectures to successfully accomplish many of the same essential and intelligent behaviors for survival, an example of convergent evolution in which organisms not closely related (i.e., not monophyletic) independently evolved similar traits or functions as a result of having to adapt to similar environments or ecological niches. But the example of convergent evolution presented in the current study is comparatively novel and unique because its identification required special tests of the cognitive ability (trait) for the cognitive function of fully learning a same/different abstract concept to be revealed. Other examples of convergent evolution have been based on some obvious physical trait, such as wings, which typically can be identified from fossil records and have an obvious function of flying (some insects, birds, and bats).

Atypical neural oscillation as a cause of dyslexia?

15 Feb

Neural oscillation refers to the rhythmic activity of large numbers of the brains neurons. It is these oscillations that produce the brain waves that are measured on a EEG. Here’s a recent paper suggesting that dyslexia may be caused by abnormal neural oscillation in parts of the brain related to auditory and visual processing. Here is the abstract:

It has been proposed that atypical neural oscillations in both the auditory and the visual modalities could explain why some individuals fail to learn to read and suffer from developmental dyslexia. However, the role of specific oscillatory mechanisms in reading acquisition is still under debate. In this article, we take a cross-linguistic approach and argue that both the phonological and orthographic specifics of a language (e.g., linguistic rhythm, orthographic depth) shape the oscillatory activity thought to contribute to reading development. The proposed theoretical framework should allow future research to test cross-linguistic hypotheses that will shed light on the heterogeneity of auditory and visual disorders and their underlying brain dysfunction(s) in developmental dyslexia, and inform clinical practice by helping us to diagnose dyslexia across languages.


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