Can cortical plasticity be retained into adulthood?

Rejuvenation of plasticity in the brain: opening the critical period (BTW, pay attention to the role of the thalamus, which is also critically involved in language processing) https://t.co/3LNCrrYfpI pic.twitter.com/vBDJLVcFbk

— A.Benítez-Burraco (@abenitezburraco) October 6, 2018

From the article: Mary H Patton, Jay A Blundon, Stanislav S Zakharenko, Rejuvenation of plasticity in the brain: opening the critical period, Current Opinion in Neurobiology, Volume 54, February 2019, Pages 83-89, https://doi.org/10.1016/j.conb.2018.09.003.

Highlights

• Critical (sensitive) period for cortical plasticity can be extended into adulthood.
• Neuromodulators reopen the critical period for cortical plasticity in adults.
• Neuromodulators operate through cortical disinhibition and thalamic adenosine.
• Cortical disinhibition is mediated by layer 1 interneurons.
• Thalamic adenosine production and A1 receptor signaling gate the critical period.

Cortical circuits are particularly sensitive to incoming sensory information during well-defined intervals of postnatal development called ‘critical periods’. The critical period for cortical plasticity closes in adults, thus restricting the brain’s ability to indiscriminately store new sensory information. For example, children acquire language in an exposure-based manner, whereas learning language in adulthood requires more effort and attention. It has been suggested that pairing sounds with the activation of neuromodulatory circuits involved in attention reopens this critical period. Here, we review two critical period hypotheses related to neuromodulation: cortical disinhibition and thalamic adenosine. We posit that these mechanisms co-regulate the critical period for auditory cortical plasticity. We also discuss ways to reopen this period and rejuvenate cortical plasticity in adults.

Note that this research is about the auditory cortex with an orientation toward language acquisition. What about music? I'm thinking, in particular, about Walter Freeman's hypothesis about intense music-centered ritual and bonding among adults, “A Neurobiological Role of Music in Social Bonding, in The Origins of Music, eds. N. L. Wallin, B. Merker, and Steve Brown (Cambridge, MA: MIT Press, 2000), 411-424.

Abstract: Music is regarded in biological terms as originating in the brain, so that most explanations concentrate on the ways in which brains process information. Recent studies of the nonlinear dynamics of the primary sensory cortices have shown that the patterns that are constructed by chaotic nonlinear dynamics in cortical neuropil replace stimulus driven activity. This finding supports the concept that knowledge in brains is entirely constructed within them without direct transfer of information from outside. As knowledge increases by learning, brains of individuals grow progressively apart. The separation results from the uniqueness of the knowledge that is constructed within each brain. The resulting condition of isolation is known among philosophers as epistemological solipsism. This view is reinforced by the tenets of aesthetics, which emphasize the deeply personal experiences of individuals, not as active listeners but as passive recipients of beauty in music and other arts. Neither conventional neuroscience nor aesthetics can explain the deep emotional power of music to move humans to action.

An alternative view is presented, in which human brains are seen to have evolved primarily in response to environmental pressures to bridge the solipsistic gulf between individuals, and to form integrated societies. An evolutionary origin is found in the neurohumoral mechanisms of parental bonding to altricial infants. A case is made that music together with dance have co-evolved biologically and culturally to serve as a technology of social bonding. Findings of anthropologists and psychiatrists are reviewed to show how the rhythmic behavioral activities that are induced by drum beats and music can lead to altered states of consciousness, through which mutual trust among members of societies is engendered.