Synaptic Plasticity Shapes Brain Connectivity: Implications for Network Topology

Abstract

Studies of brain network connectivity improved understanding on brain changes and adaptation in response to different pathologies. Synaptic plasticity, the ability of neurons to modify their connections, is involved in brain network remodeling following different types of brain damage (e.g., vascular, neurodegenerative, inflammatory). Although synaptic plasticity mechanisms have been extensively elucidated, how neural plasticity can shape network organization is far from being completely understood. Similarities existing between synaptic plasticity and principles governing brain network organization could be helpful to define brain network properties and reorganization profiles after damage. In this review, we discuss how different forms of synaptic plasticity, including homeostatic and anti-homeostatic mechanisms, could be directly involved in generating specific brain network characteristics. We propose that long-term potentiation could represent the neurophysiological basis for the formation of highly connected nodes (hubs). Conversely, homeostatic plasticity may contribute to stabilize network activity preventing poor and excessive connectivity in the peripheral nodes. In addition, synaptic plasticity dysfunction may drive brain network disruption in neuropsychiatric conditions such as Alzheimer’s disease and schizophrenia. Optimal network architecture, characterized by efficient information processing and resilience, and reorganization after damage strictly depend on the balance between these forms of plasticity.

Differentiating Responders and Non-responders to rTMS Treatment for Disorder of Consciousness Using EEG After-Effects

“…Fast Fourier transform (2 s Hamming) was applied to estimate the EEG power at different frequency bands. Absolute power was obtained for the delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), beta (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), and gamma (30-40 Hz) bands of the whole brain and all electrodes (24). The relative power calculated from absolute power was used to measure the EEG after-effects induced by rTMS at the delta, theta, alpha, beta, and gamma bands.…”

“…Koch et al (11) demonstrated the impairment of LTPlike together with normal LTD-like cortical plasticity in patients with Alzheimer's Disease (AD) and TMS has been introduced as a novel therapeutic approaches in AD (12). In the neural system, the LTP/LTD-like mechanism is thought to play important roles in brain network recovery, and is considered a promising way for improving DOC outcome (13).…”

Mal de Debarquement Syndrome: A Matter of Loops?

“…The mathematical analysis of our neural loop system shows that the tendency to oscillate increases for increasing strength of inhibitory pathways, while it reaches its maximum when the strength of both inhibitory and excitatory pathways is high. Such a result strongly suggests that the over-synchronization of the internal oscillator may be found in synaptic plasticity (56), which can induce variations of connection strength in the neural loop system. Most notably, a typical example of this kind of neuronal rearrangement is long-term potentiation (LTP) (57).…”

The Role of Acupuncture Improving Cognitive Deficits due to Alzheimer’s Disease or Vascular Diseases through Regulating Neuroplasticity

“…For example, some rapidly and reversibly increased or decreased strengths of brain network connections, also known as altered recruitments of functional connections normally devoted to performing a given task or the recruitment of additional network connections that are not typically activated by healthy people. And the alteration of network connectivity is a form of neuroplasticity that could indicate compensatory mechanisms engaged to maintain a normal level of cognitive function or promote the recovery from cognitive dysfunction due to the primary white matter lesions and neuronal loss [ 14 , 114 , 115 ].…”