HANDSHAKES MAY ENGAGE OUR SENSE OF SMELL

Why do people shake hands? A new Weizmann Institute study suggests one of the reasons for this ancient custom may be to check out each other's odors. Even if we are not consciously aware of this, handshaking may provide people with a socially acceptable way of communicating via the sense of smell

Not only do people often sniff their own hands, but they do so for a much longer time after shaking someone else's hand, the study has found. As reported today in the journal eLife, the number of seconds the subjects spent sniffing their own right hand more than doubled after an experimenter greeted them with a handshake.

"Our findings suggest that people are not just passively exposed to socially-significant chemical signals, but actively seek them out," said Idan Frumin, the research student who conducted the study under the guidance of Prof. Noam Sobel of Weizmann's Neurobiology Department. "Rodents, dogs and other mammals commonly sniff themselves, and they sniff one another in social interactions, and it seems that in the course of evolution, humans have retained this practice -- only on a subliminal level."

To examine whether handshakes indeed transfer body odors, the researchers first had experimenters wearing gloves shake the subjects' bare hands, then tested the glove for smell residues. They found that a handshake alone was sufficient for the transfer of several odors known to serve as meaningful chemical signals in mammals. "It's well known that germs can be passed on through skin contact in handshakes, but we've shown that potential chemical messages, known as chemosignals, can be passed on in the same manner," Frumin says.

Next, to explore the potential role of handshakes in communicating odors, the scientists used covert cameras to film some 280 volunteers before and after they were greeted by an experimenter, who either shook their hand or didn't. The researchers found that after shaking hands with an experimenter of the same gender, subjects more than doubled the time they later spent sniffing their own right hand (the shaking one). In contrast, after shaking hands with an experimenter of the opposite gender, subjects increased the sniffing of their own left hand (the non-shaking one). "The sense of smell plays a particularly important role in interactions within gender, not only across gender as commonly assumed," Frumin says.

The scientists then performed a series of tests to make sure the hand-sniffing indeed served the purpose of checking out odors and was not merely a stress-related response to a strange situation. First, they measured nasal airflow during the task and found that subjects were truly sniffing their hands and not just lifting them to their nose. It turned out that the amount of air inhaled by the volunteers through the nose doubled when they brought their hands to their face. Next, the scientists found they could manipulate the hand-sniffing by artificially introducing different smells into the experimental setting. For example, when experimenters were tainted with a commercial unisex perfume, the hand-sniffing increased. In contrast, when the experimenters were tainted with odors derived from sex hormones, the sniffing decreased. These final tests confirmed the olfactory nature of the hand-sniffing behavior.

Taking part in the study were Ofer Perl, Yaara Endevelt-Shapira, Ami Eisen, Neetai Eshel, Iris Heller, Maya Shemesh, Aharon Ravia, Dr. Lee Sela and Dr. Anat Arzi, all of Prof. Sobel's lab

"Handshakes vary in strength, duration and posture, so they convey social information of various sorts," says Prof. Sobel. "But our findings suggest that at its evolutionary origins, handshaking might have also served to convey odor signals, and such signaling may still be a meaningful, albeit subliminal, component of this custom."

Why Do Our Hands And Or Feet Tingle

Today's post from webmd.com (see link below) is a thorough answer to the question why our hands and feet tingle. Many people ask this question long before having heard the word neuropathy and for many people, the symptoms are temporary but equally, for millions across the world, the symptoms never go away and become progressively worse. They then have a form of neuropathy or nerve damage. This article will set you on the right path as regards opening information; after that, you need to discuss your problem with your doctor and do as much further research of your own until you have built up sufficient knowledge to be best able to live with the disease.

Tingling in Hands and Feet
WebMD Medical Reference View Article Sources
Reviewed by Varnada Karriem-Norwood, MD on September 26, 2014

Tingling hands, feet, or both is an extremely common and bothersome symptom. Such tingling can sometimes be benign and temporary. For example, it could result from pressure on nerves when your arm is crooked under your head as you fall asleep. Or it could be from pressure on nerves when you cross your legs too long. In either case, the "pins and needles" effect -- which is usually painless -- is soon relieved by removing the pressure that caused it.

In many cases, however, tingling in the hands, feet, or both can be severe, episodic, or chronic. It also can accompany other symptoms. such as pain, itching, numbness, and muscle wasting. In such cases, tingling may be a sign of nerve damage, which can result from causes as varied as traumatic injuries or repetitive stress injuries, bacterial or viral infections, toxic exposures, and systemic diseases such as diabetes.

Such nerve damage is known as peripheral neuropathy because it affects nerves distant from the brain and spinal cord, often in the hands and feet. There are more than 100 different types of peripheral neuropathy. Over time, peripheral neuropathy can worsen, resulting in decreased mobility and even disability. More than 20 million Americans, most of them older adults, are estimated to have peripheral neuropathy.

It's important to seek prompt medical evaluation for any persistent tingling in your hands, feet, or both. The earlier the underlying cause of your tingling is identified and brought under control, the less likely you are to suffer potentially lifelong consequences.

Causes of Tingling in the Hands and Feet

Diabetes is one of the most common causes of peripheral neuropathy, accounting for about 30% of cases. In diabetic neuropathy, tingling and other symptoms often first develop in both feet and go up the legs, followed by tingling and other symptoms that affect both hands and go up the arms. About two-thirds of people with diabetes have mild to severe forms of nerve damage. In many cases, these symptoms are the first signs of diabetes.

In another 30% of peripheral neuropathy cases, the cause is unknown or "idiopathic."

The remaining 40% of cases have a variety of causes such as:

Nerve entrapment syndromes. These include carpal tunnel syndrome, ulnar nerve palsy, peroneal nerve palsy, and radial nerve palsy.

Systemic diseases. These include kidney disorders, liver disease, vascular damage and blood diseases, amyloidosis, connective tissue disorders and chronic inflammation, hormonal imbalances (including hypothyroidism), and cancers and benign tumors that impinge on nerves.

Vitamin deficiencies. Vitamins E, B1, B6, B12, and niacin are essential for healthy nerve function. A B12 deficiency, for example, can lead to pernicious anemia, an important cause of peripheral neuropathy. But too much B6 also can cause tingling in the hands and feet.

Alcoholism. Alcoholics are more likely to have a thiamine or other important vitamin deficiencies because of poor dietary habits, a common cause of peripheral neuropathy. It's also possible that alcoholism itself can cause nerve damage, a condition that some researchers call alcoholic neuropathy.

Toxins. These include heavy metals such as lead, arsenic, mercury, and thallium, and some industrial and environmental chemicals. They also include certain medications -- especially chemotherapy drugs used for lung cancer -- but also some antiviral and antibiotic drugs.

Infections. These include Lyme disease, shingles (varicella-zoster), cytomegalovirus, Epstein-Barr, herpes simplex, and HIV/AIDS.

Autoimmune diseases. These include Guillain-Barre syndrome, lupus, and rheumatoid arthritis.

Inherited disorders. These include a group of disorders collectively known as Charcot-Marie-Tooth disease.

Injury. Often related to trauma, nerves can be compressed, crushed, or damaged, resulting in nerve pain. Examples include nerve compression caused by a herniated disc or dislocated bone.

Diagnosis of Tingling Hands and Feet

If you seek care for your tingling hands or feet, your health care provider will do a physical exam and take an extensive medical history addressing your symptoms, work environment, social habits (including alcohol use), toxic exposure, risk of HIV or other infectious diseases, and family history of neurological disease.

He or she also may perform additional tests such as:
Blood tests. These can include tests to detect diabetes, vitamin deficiencies, liver or kidney dysfunction, other metabolic disorders, and signs of abnormal immune system activity.
An examination of cerebrospinal fluid. This can identify antibodies associated with peripheral neuropathy.
An electromyogram (EMG), a test of the electrical activity of muscle
Nerve conduction velocity (NCV)

Other tests may include:
Computed tomography (CT)
Magnetic resonance imaging (MRI)
Nerve biopsy
Skin biopsy to look at nerve fiber endings

Treatments for Tingling Hands and Feet

Successful treatment depends on an accurate diagnosis and treatment of the underlying cause of the tingling. As long as the peripheral nerve cells have not been killed, they have the ability to regenerate.

Although no treatments are available for inherited types of peripheral neuropathy, many of the acquired types can be improved with treatment. For example, good blood sugar control in diabetes can slow the progression of diabetic neuropathy; vitamin supplementation can correct peripheral neuropathy in people with vitamin deficiencies.

General lifestyle recommendations include maintaining an optimal weight, avoiding exposure to toxins, following a doctor-supervised exercise program, eating a balanced diet, and avoiding or limiting alcohol consumption. Recommendations also include quitting smoking, which constricts blood supply to blood vessels supplying nutrients to peripheral nerves.

In some cases, tingling and other symptoms of peripheral neuropathy may be reduced with prescriptions originally developed for treating seizures and depression.

http://www.webmd.com/brain/tingling-in-hands-and-feet

How We Perceive Our Neuropathic Pain

Another interesting article from sciencedaily.com (see link below)looks once more at the science behind pain and in this case, the molecular science involved with how the body responds to pain. Apparently, removing what was thought to be the main pain receptor in mice, didn't remove the problem and the pain returned. Not reaaly surprising after it was discovered that even simple organisms like flatworms have back-up plans and fail-safes involving multiple pain receptors. If pain receptors are 'switched off' then others will jump in to save the day. Who knew we were so much like our computers!

An Airbag for Perceiving Pain: Basic Mechanisms Governing the Perception of Pain Discovered
ScienceDaily (Apr. 4, 2012)

Everyone knows how it feels to bite into a hot chili pepper or burn the roof of one's mouth with a hot drink. This activates nerve cells that relay the potential threat to the brain, which then causes the person in question to perceive pain. Over 14 years ago, researchers discovered the first receptor molecule that reacts to heat as well as to capsaicin, the active substance in chili extracts. At the time it was believed that science had come a big step closer to understanding the emergence of pain and its treatment with medicine.

The disappointment was great when it was found several years later that laboratory mice from whom the gene of this receptor had been artificially removed still perceived pain. Despite repeated attempts to explain the causes of this observation, it has remained a mystery until now. Researchers at the University of Freiburg have now deciphered basic mechanisms governing the perception of pain. Their findings, published in the current issue of the journal PLoS One, demonstrate that even simple organisms possess sensor systems with multiple safeguards for the perception of painful stimuli like heat.

"When we discovered that the roundworm C. elegans, which can be found in every shovelful of earth, has the same receptor genes as humans, we were optimistic that this model could help us to reveal the secret of the perception of pain," says Prof. Dr. Ralf Baumeister from the Laboratory for Bioinformatics and Molecular Genetics of the Faculty of Biology of his research team's experiments over the past years. This potentially life-saving mechanism is exceptionally well safeguarded even in such a simple animal as a roundworm. The roundworm only has 302 nerve cells at its disposal, but this small number is sufficient for complex behaviors and even for learning processes. Much as modern automobiles are equipped with electronic backup systems designed to take over and prevent fatal consequences for the passengers when a part fails, the study shows that the worm uses at least six of these cells as sensors to detect dangerous heat. In order to perceive pain, however, the worm needs to use more than one of them at a time.

In addition, one and the same cell can react to the painful stimulus with two different molecular mechanisms. Team members Shu Liu and Dr. Ekkehard Schulze thus had to apply a combination of microsurgical techniques and methods from microsystems engineering and genetics in order to grasp the mechanisms the worm uses to perceive dangerous levels of heat in all of their complexity. According to the researchers, the findings can now be used to discover and understand the interactions between the various mechanisms for these processes in humans. At least every tenth person in the Federal Republic of Germany suffers regularly from strong to very strong pain. Hence, the team's research on the tiny laboratory worm C. elegans is something everyone will ultimately profit from.

http://www.sciencedaily.com/releases/2012/04/120404102539.htm

DOGS HEAR OUR WORDS AND HOW WE SAY THEM

When people hear another person talking to them, they respond not only to what is being said--those consonants and vowels strung together into words and sentences--but also to other features of that speech--the emotional tone and the speaker's gender, for instance. Now, a report in the Cell Press journal Current Biology on November 26 provides some of the first evidence of how dogs also differentiate and process those various components of human speech.

"Although we cannot say how much or in what way dogs understand information in speech from our study, we can say that dogs react to both verbal and speaker-related information and that these components appear to be processed in different areas of the dog's brain," says Victoria Ratcliffe of the School of Psychology at the University of Sussex.

Previous studies showed that dogs have hemispheric biases--left brain versus right--when they process the vocalization sounds of other dogs. Ratcliffe and her supervisor David Reby say it was a logical next step to investigate whether dogs show similar biases in response to the information transmitted in human speech. They played speech from either side of the dog so that the sounds entered each of their ears at the same time and with the same amplitude.

"The input from each ear is mainly transmitted to the opposite hemisphere of the brain," Ratcliffe explains. "If one hemisphere is more specialized in processing certain information in the sound, then that information is perceived as coming from the opposite ear."

If the dog turned to its left, that showed that the information in the sound being played was heard more prominently by the left ear, suggesting that the right hemisphere is more specialized in processing that kind of information.

The researchers did observe general biases in dogs' responses to particular aspects of human speech. When presented with familiar spoken commands in which the meaningful components of words were made more obvious, dogs showed a left-hemisphere processing bias, as indicated by turning to the right. When the intonation or speaker-related vocal cues were exaggerated instead, dogs showed a significant right-hemisphere bias.

"This is particularly interesting because our results suggest that the processing of speech components in the dog's brain is divided between the two hemispheres in a way that is actually very similar to the way it is separated in the human brain," Reby says.

Of course, it doesn't mean that dogs actually understand everything that we humans might say or that they have a human-like ability of language--far from it. But, says Ratcliffe, these results support the idea that our canine companions are paying attention "not only to who we are and how we say things, but also to what we say."

All of this should come as good news to many of us dog-loving humans, as we spend considerable time talking to our respective pups already. They might not always understand you, but they really are listening.