Activity-dependent increases in [Ca2+]i contribute to digital-analog plasticity at a molluscan synapse
In a type of short-term plasticity that is observed in a number of systems, synaptic transmission is potentiated by depolarizing changes in the membrane potential of the presynaptic neuron before spike initiation. This digital-analog form of plasticity is graded. The more depolarized the neuron, the greater the increase in the efficacy of synaptic transmission. In a number of systems, including the system presently under investigation, this type of modulation is calcium dependent, and its graded nature is presumably a consequence of a direct relationship between the intracellular calcium concentration ([Ca2+]i) and the eff...
Source: Journal of Neurophysiology - June 1, 2017 Category: Neurology Authors: Ludwar, B. C., Evans, C. G., Cambi, M., Cropper, E. C. Tags: Research Articles Source Type: research
Perceptual and categorical decision making: goal-relevant representation of two domains at different levels of abstraction
To date it has been unclear whether perceptual decision making and rule-based categorization reflect activation of similar cognitive processes and brain regions. On one hand, both map potentially ambiguous stimuli to a smaller set of motor responses. On the other hand, decisions about perceptual salience typically concern concrete sensory representations derived from a noisy stimulus, while categorization is typically conceptualized as an abstract decision about membership in a potentially arbitrary set. Previous work has primarily examined these types of decisions in isolation. Here we independently varied salience in bot...
Source: Journal of Neurophysiology - June 1, 2017 Category: Neurology Authors: Shankar, S., Kayser, A. S. Tags: Research Articles Source Type: research
Probing phase- and frequency-dependent characteristics of cortical interneurons using combined transcranial alternating current stimulation and transcranial magnetic stimulation
Paired-pulse transcranial magnetic stimulation (TMS) and peripheral stimulation combined with TMS can be used to study cortical interneuronal circuitry. By combining these procedures with concurrent transcranial alternating current stimulation (tACS), Guerra and colleagues recently showed that different cortical interneuronal populations are differentially modulated by the phase and frequency of tACS-imposed oscillations (Guerra A, Pogosyan A, Nowak M, Tan H, Ferreri F, Di Lazzaro V, Brown P. Cerebral Cortex 26: 3977–2990, 2016). This work suggests that different cortical interneuronal populations can be characterize...
Source: Journal of Neurophysiology - June 1, 2017 Category: Neurology Authors: Hussain, S. J., Thirugnanasambandam, N. Tags: Neuro Forum Source Type: research
mTOR regulates peripheral nerve response to tensile strain
While excessive tensile strain can be detrimental to nerve function, strain can be a positive regulator of neuronal outgrowth. We used an in vivo rat model of sciatic nerve strain to investigate signaling mechanisms underlying peripheral nerve response to deformation. Nerves were deformed by 11% and did not demonstrate deficits in compound action potential latency or amplitude during or after 6 h of strain. As revealed by Western blotting, application of strain resulted in significant upregulation of mammalian target of rapamycin (mTOR) and S6 signaling in nerves, increased myelin basic protein (MBP) and β-actin level...
Source: Journal of Neurophysiology - May 16, 2017 Category: Neurology Authors: Love, J. M., Bober, B. G., Orozco, E., White, A. T., Bremner, S. N., Lovering, R. M., Schenk, S., Shah, S. B. Tags: Research Articles Source Type: research
Reflex wind-up in early chronic spinal injury: plasticity of motor outputs
This report is a continuation of our previous paper on reflex wind-up in the intact and acutely spinalized cat. To evaluate reflex wind-up in both studies, we recorded electromyographic signals from the following left hindlimb muscles: lateral gastrocnemius (LG), tibialis anterior (TA), semitendinosus (ST), and sartorius (Srt), in response to 10 electrical pulses to the tibial or superficial peroneal nerves. Two distinct components of the reflex responses were considered, a short-latency compound action potential (CAP) and a longer duration bout of sustained activity (SA). These two response types were shown to be differen...
Source: Journal of Neurophysiology - May 16, 2017 Category: Neurology Authors: Johnson, M. D., Frigon, A., Hurteau, M.-F., Cain, C., Heckman, C. J. Tags: Research Articles Source Type: research
