Why Wolves Are Forever Wild, but Dogs Can Be Tamed

Dogs and wolves are genetically so similar, it's been difficult for biologists to understand why wolves remain fiercely wild, while dogs can gladly become "man's best friend." Now, doctoral research by evolutionary biologist Kathryn Lord at the University of Massachusetts Amherst suggests the different behaviors are related to the animals' earliest sensory experiences and the critical period of socialization. Details appear in the current issue of Ethology.

When the socialization window is open, wolf and dog pups begin walking and exploring without fear and will retain familiarity throughout their lives with those things they contact. Domestic dogs can be introduced to humans, horses and even cats at this stage and be comfortable with them forever. But as the period progresses, fear increases and after the window closes, new sights, sounds and smells will elicit a fear response.  Through observations, Lord confirmed that both wolf pups and dogs develop the sense of smell at age two weeks, hearing at four weeks and vision by age six weeks on average. However, these two subspecies enter the critical period of socialization at different ages. Dogs begin the period at four weeks, while wolves begin at two weeks. Therefore, how each subspecies experiences the world during that all-important month is extremely different, and likely leads to different developmental paths, she says.
Science Daily, Jan. 17, 2013

Kathryn Lord.

A Comparison of the Sensory Development of Wolves (Canis lupus lupus) and Dogs (Canis lupus familiaris). 

Ethology, 2013; 119 (2): 110 DOI:10.1111/eth.12044

New Implant Replaces Impaired Middle Ear

Functionally deaf patients can gain normal hearing with a new implant that replaces the middle ear. The unique invention from the Chalmers University of Technology has been approved for a clinical study. The first operation was performed on a patient in December 2012.

Jan. 14, 2013 — Science Daily

Regenerate Sensory Hair Cells, Restore Hearing to Noise-Damaged Ears

Hearing loss is a significant public health problem affecting almost 50 million people in the United States alone. Sensorineural hearing loss is the most common form and is caused by the loss of sensory hair cells in the cochlea. Hair cell loss results from a variety of factors including noise exposure, aging, toxins, infections, and certain antibiotics and anti-cancer drugs. Although hearing aids and cochlear implants can ameliorate the symptoms somewhat, there are no known treatments to restore hearing, because auditory hair cells in mammals, unlike those in birds or fish, do not regenerate once lost. Auditory hair cell replacement holds great promise as a treatment that could restore hearing after loss of hair cells.

In the Jan. 10 issue of Neuron, Massachusetts Eye and Ear and Harvard Medical School researchers demonstrate for the first time that hair cells can be regenerated in an adult mammalian ear by using a drug to stimulate resident cells to become new hair cells, resulting in partial recovery of hearing in mouse ears damaged by noise trauma. This finding holds great potential for future therapeutic application that may someday reverse deafness in humans.

Notch Inhibition Induces Cochlear Hair Cell Regeneration and Recovery of Hearing after Acoustic Trauma
Kunio Mizutari, et al.
Neuron, Volume 77, Issue 1, 58-69, 9 January 2013, 10.1016/j.neuron.2012.11.032

Ion Channels | TRP Channels in Drosophila Auditory Transduction

In this study, Lehnert et al. record spikes and subthreshold activity from a genetically defined population ofDrosophila auditory receptor neurons. These recordings reveal that several TRP family members play distinct roles in converting movement to transduction currents.

Lehnert et al.
Neuron, Volume 77, Issue 1, 115-128, 9 January 2013
10.1016/j.neuron.2012.11.030

Hearing Impairment: A Panoply of Genes and Functions

Research in the genetics of hearing and deafness has evolved rapidly over the past years, providing the molecular foundation for different aspects of the mechanism of hearing. Considered to be the most common sensory disorder, hearing impairment is genetically heterogeneous. The multitude of genes affected encode proteins associated with many different functions, encompassing overarching areas of research. These include, but are not limited to, developmental biology, cell biology, physiology, and neurobiology. In this review, we discuss the broad categories of genes involved in hearing and deafness. Particular attention is paid to a subgroup of genes associated with inner ear gene regulation, fluid homeostasis, junctional complex and tight junctions, synaptic transmission, and auditory pathways. Overall, studies in genetics have provided research scientists and clinicians with insight regarding practical implications for the hearing impaired, while heralding hope for future development of therapeutics.

Amiel A. Dror, et al.
Neuron, Volume 68, Issue 2, 293-308, 21 October 2010
10.1016/j.neuron.2010.10.011