Auditory Neuroplasticity: Not what we are Thinking it is

Nothing is more frustrating to a productive scientist than the unshakable paradigm! Often, it seems that popular theories are more than justly influenced by politics, economics, the media, or by the mistaken mindset of the scientific community. An example that illustrates this is in the book, Predictably Irrational: The Hidden Forces That Shape Our Decisions, by author Dan Ariely [1]. This work offers an amusing description of one of the many human tendencies, that is, the tendency toward ownership (chapter 8, The High Price of Ownership) and how this tendency leads to fallible decision making. Ariely describes several “peculiarities” of ownership, including the one: “the harder we work on something, the more we start feeling about [it] as our own.” Certainly, we can draw a parallel between this and what seems to be a persistent problem in science; that is, the more time researchers spend forming theories, the more likely they are to become attached to them. This is perhaps most evident in fields of study where hypothesis testing and theory forming are constrained by the complexity, delicacy, or absolute mystery, of the subject at hand.

The articles presented in this special issue, Auditory Neuroplasticity, effectively distill a few of the mysteries related to the difficult study of the neurological processing of sound. Of particular interest, esteemed researcher Norman M. Weinberger, from the Center for Neurobiology of Learning and Memory, University of California, poses a provocative argument that the function of the primary auditory cortex (A1), in humans and animals, is more involved in learning, memory and other complex processes than what is popularly thought. His review article, “Plasticity in the Primary Auditory Cortex, Not What You Think IT IS: Implications for Basic and Clinical Auditory Neuroscience,” is an exemplary thought-piece that resonates with a tone of true academic discourse. Herein, Dr. Weinberger provides support for his argument with a concise, though not exhaustive, review of the literature. He purports that there is a growing body of evidence that A1 is “deeply involved in ‘cognitive’ functions,” which the author says are attention, learning, memory concept formation, and problem solving. In fact, Dr. Weinberger carries on suggesting that the last twenty years of discovery and elaboration of Associative Representational Plasticity (ARP) in the A1 has produced a “crisis for this standard model.”

The standard model, according to Dr. Weinberger, holds that A1 function is purely (and solely) one of acoustic analyzer, responding selectively to the particular physical parameters of sound. First evidence of this stretches back to the early 20^th century and was supposedly confirmed in successive electrophysiological studies, which were performed on anesthetized animals. He says that as “experiments were extended to waking subjects; it became obvious that the fixed relationship between a stimulus parameter and a cortical response was not as rigid as had been assumed.”

So, what did the researchers find when working with nonanesthetized subjects? Essentially, one group, and many who would follow, found an increase in the amplitude of A1 evoked potentials in the cat when a click stimulus was paired with a mild shock, giving way to speculation that A1 plasticity could be altered by anticipation and memory. This, and many similar experiments that followed until the mid-1980s, apparently demonstrated ‘associative neural plasticity’ in the primary auditory cortex (A1), according to Dr. Weinberger. And, here lies the controversy. Simply, we learn from Dr. Weinberger’s argument that the two models of A1 function, the “standard model” and the alternative, which views A1 as having associative representational plasticity, continue on parallel paths, never intersecting. This is disappointing, as integration of these competing models into a single, unified one could arguably lead to a more accurate translation of theory into useful clinical application.

The issues raised in Dr. Weinberger’s article highlight the reality that we must remain willing to sometimes challenge popular beliefs in lieu of new observations. It is my view that open access journals, such as this one, are an important, emerging component of current scientific discourse. This format ensures that new, meritorious studies can be published in a timely manner and openly shared with the community, irrespective of controversy or author pedigree. Open access journals may provide a new avenue in which hypotheses can be more directly challenged and modified.