title: In vivo evidence for neuroplasticity in older adults.
abstract: Neuroplasticity can be conceptualized as an intrinsic property of the brain that enables modification of function and structure in response to environmental demands. Neuroplastic strengthening of synapses is believed to serve as a critical mechanism underlying learning, memory, and other cognitive functions. Ex vivo work investigating neuroplasticity has been done on hippocampal slices using high frequency stimulation. However, in vivo neuroplasticity in humans has been difficult to demonstrate. Recently, a long-term potentiation-like phenomenon, a form of neuroplastic change, was identified in young adults by differences in visual evoked potentials (VEPs) that were measured before and after tetanic visual stimulation (TVS). The current study investigated whether neuroplastic changes in the visual pathway can persist in older adults. Seventeen healthy subjects, 65 years and older, were recruited from the community. Subjects had a mean age of 77.4 years, mean education of 17 years, mean MMSE of 29.1, and demonstrated normal performance on neuropsychological tests. 1Hz checkerboard stimulation, presented randomly to the right or left visual hemi-field, was followed by 2min of 9Hz stimulation (TVS) to one hemi-field. After 2min of rest, 1Hz stimulation was repeated. Temporospatial principal component analysis was used to identify the N1b component of the VEPs, at lateral occipital locations, in response to 1Hz stimulation pre- and post-TVS. Results showed that the amplitude of factors representing the early and late N1b component was substantially larger after tetanic stimulation. These findings indicate that high frequency visual stimulation can enhance the N1b in cognitively high functioning old adults, suggesting that neuroplastic changes in visual pathways can continue into late life. Future studies are needed to determine the extent to which this marker of neuroplasticity is sustained over a longer period of time, and is influenced by age, cognitive status, and neurodegenerative disease.
authors: Laboratory of Healthy Cognitive Aging, Division of Cognitive and Behavioral Neurology and Center for Brain/Mind Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: portofhg@gmail.com.
authors: Fábio Henrique de Gobbi
authors: FH
authors: Porto
authors: Laboratory of Healthy Cognitive Aging, Division of Cognitive and Behavioral Neurology and Center for Brain/Mind Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: afox4@partners.org.
authors: Anne Murphy
authors: AM
authors: Fox
authors: Laboratory of Healthy Cognitive Aging, Division of Cognitive and Behavioral Neurology and Center for Brain/Mind Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: etusch@partners.org.
authors: Erich S
authors: ES
authors: Tusch
authors: Division of Stroke and Cerebrovascular Disease, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: fsorond@partners.org.
authors: Farzaneh
authors: F
authors: Sorond
authors: Department of Psychology, Linnaeus University, Växjö, Sweden; Center for Alzheimer Research, Department of NVS, Karolinska Institutet, Huddinge, Sweden. Electronic address: Abdul.mohammed@lnu.se.
authors: Abdul H
authors: AH
authors: Mohammed
authors: Laboratory of Healthy Cognitive Aging, Division of Cognitive and Behavioral Neurology and Center for Brain/Mind Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: kdaffner@partners.org.
authors: Kirk R
authors: KR
authors: Daffner
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology*; D009483:Neuropsychological Tests; D010775:Photic Stimulation / Q000379:methods; D025341:Principal Component Analysis; D012815:Signal Processing, Computer-Assisted
keywords: Neuroplasticity; Normal cognitive aging; Tetanic visual; Visual evoked potentials (VEPs)