Informal Seminar - Jonathan Wolpaw
Breakfast: 10:30 am
Seminar: 11 am
Abstract: Recent recognition that the CNS is ubiquitously plastic through life creates the need for a new paradigm that can explain how skilled behaviors (skills) are acquired and maintained in the continually changing CNS. The paradigm's core is a newly recognized CNS entity, now given the name "heksor" (from the ancient Greek term "hexis") (JPhysiol 2022 DOI:10.1113/JP283291). A heksor is the substrate of a skill; it is a distributed network of neurons and synapses that may extend from cortex to spinal cord. A heksor has two essential properties. First, it changes itself as needed to maintain the key features of its skill, the attributes that make the skill satisfactory. For example, the CNS activity, muscle activity, and kinematics of locomotion may change, but its key features (e.g., upright posture, good balance, right/left symmetry, acceptable metabolic cost) are maintained. Second, through their concurrent changes, the many heksors that share the CNS negotiate the properties of the neurons and synapses they all use. Heksors keep the CNS in a state of negotiated equilibrium that enables each to maintain its skill. In the context of this new paradigm, the term "memory" applies to the key features that a heksor maintains. The neurons and synapses comprising a heksor change continually through life. The key features of the skill that the heksor produces do not change. These key features are the memory; it is recognizable primarily in the skill that is produced. As the CNS changes with new learning, growth, aging, and other life events, the plasticity of the heksor ensures the stability of the memory. Animal and human studies support this new paradigm; and it can explain otherwise inexplicable results. The paradigm also underlies new strategies for rehabilitation that are now proving successful in studies of people with spinal cord injury, stroke, and other disorders. Furthermore, the paradigm offers new answers to questions such as generation and function of spontaneous neuronal activity, etiology of muscle synergies, and control of homeostatic plasticity. The paradigm makes predictions that are testable in humans and/or animals. The first of these studies are yielding positive results.