Long‐term potentiation of human visual evoked responses

Abstract

Long-term potentiation (LTP) is a candidate synaptic mechanism underlying learning and memory that has been studied extensively at the cellular and molecular level in laboratory animals. To date, LTP has only been directly demonstrated in humans in isolated cortical tissue obtained from patients undergoing surgery, where it displays properties identical to those seen in non-human preparations. Inquiry into the functional significance of LTP has been hindered by the absence of a human model. Here we give the first demonstration that the rapid repetitive presentation of a visual checkerboard (a photic 'tetanus') leads to a persistent enhancement of one of the early components of the visual evoked potential in normal humans. The potentiated response is largest in the hemisphere contralateral to the tetanized visual hemifield and is limited to one component of the visual evoked response (the N1b). The selective potentiation of only the N1b component makes overall brain excitability changes unlikely and suggests that the effect is due instead to an LTP process. While LTP is known to exist in the human brain, the ability to elicit LTP from non-surgical patients will provide a human model system allowing the detailed examination of synaptic plasticity in normal subjects and may have future clinical applications in the assessment of cognitive disorders.

Augmenting NMDA receptor signaling boosts experience-dependent neuroplasticity in the adult human brain

“…It persists into adulthood, is frequently NMDAR dependent, and has been observed at subcortical and sensory cortex synapses (1-6). Although classical LTP studies used high-frequency electrical stimulation to induce LTP, HFvS also induces lasting potentiation of neural responses (8)(9)(10)(11)(12)(13)(14), and potentiated neural responses following HFvS show cardinal features of synaptic LTP (7,8). In the current study, participants who received DCS showed greater potentiation of the VEP following HFvS compared with participants who received placebo.…”

“…Furthermore, these LTP-like changes can be measured noninvasively as changes in sensory evoked potentials, which are stimulus-synchronized electroencephalograph (EEG) signals that result from postsynaptic potentials in populations of sensory neurons. High-frequency sensory stimulation has thus been shown to induce lasting potentiation of visual and auditory evoked potentials in human adults (9,10) and has been used to demonstrate that Significance Experience-dependent plasticity is the capacity of the brain to undergo changes following environmental input and use, and is a primary means through which the adult brain enables new behavior. In the current study, we provide evidence that enhancing signaling at the glutamate N-methyl-D-aspartate receptor (NMDAR) can enhance the mechanism underlying many forms of experiencedependent plasticity (i.e., long-term potentiation of synaptic currents) and also enhance experience-dependent learning in healthy adult humans.…”

Long-Term Plasticity in Mouse Sensorimotor Circuits after Rhythmic Whisker Stimulation

“…To our knowledge, this is the first study that reports on the spatiotemporal dynamics of such stimulus-induced and frequency-specific plasticity in the mature somatosensory-motor cortex. Overall, our data, along with earlier reports in other sensory modalities and species (Clapp et al, , 2006Teyler et al, 2005), suggest that rhythmically patterned natural stimuli can change the cerebral processing of sensory information and that this type of plasticity might be a widespread feature of the mammalian brain. Future studies could focus on the physiological relevance of our findings.…”

“…It might also be that this activity facilitates the generation of long-term adaptive changes in cortical function that underlie perception (Gilbert et al, 2001). Recent evidence suggests that periods of rhythmical visual or auditory stimulation can induce properties of synaptic plasticity such as long-term potentiation of cortical responses evoked by sensory inputs (Clapp et al, , 2006Teyler et al, 2005). Whether similar mechanisms could be related to whisking activity and whether such changes could be behaviorally relevant is not known.…”

Inhibition de l’apprentissage et de la mémoire par les anesthésiques généraux

“…[94][95][96] Long-term potentiation may account for many types of learning, from the relatively simple classical conditioning that occurs in all animals [97][98][99] to the more complex higher-level cognition observed in humans. 94,100 The opposite process, long-term depression of synaptic strength, is also necessary and is normally involved in memory storage. 101,102 Both the strengthening and weakening of synapses between neurons are involved in the reshaping of the neural network and the encoding of a novel engram.…”