Below please find information in regards to Psychology (Behavioral and Cognitive Neuroscience) PhD student lvan Iotzov’s second exam (defense of research proposal), which is open to all and will take place on Tuesday, May 25th at 11:00am via Zoom (email iiotzov@gradcenter.cuny.edu for Zoom ID). Ivan's abstract is also below.

Neural Speech Tracking: Mechanisms and Practical Applications

Speech signals have a strong and consistent effect on brain activity. Many previous studies have demonstrated the ability to find correlations between the amplitude envelope of ongoing speech and evoked responses measured through EEG or MEG. This correlation appears to be modulated by attention, as well as other high-level factors. It is of particular interest because of the possible practical applications of speech tracking in the steering of hearing aid devices and other assistive hearing devices. These devices are typically difficult to tune and the ability to use an objective neural signal as the basis for their tuning would be a great advancement in comfort and efficacy for their users. In this proposal, investigate the correlation between speech intelligibility and the neural tracking of a speech segment. We show a link between the neural tracking of speech and performance on a behavioral word-recognition task. We also develop a novel behavioral paradigm for the investigation of these effects and show preliminary data demonstrating the validity of this new paradigm. Additionally, we propose further experiments to illuminate the mechanisms behind this speech tracking phenomenon using novel manipulations of speech stimuli. Together, these aims and methods provide a basis for the use of speech tracking as an objective neural measure of intelligibility of speech and look to shed light on the oscillatory mechanisms that create the speech tracking phenomenon.

Forouzan V. Farahani, a PhD student in the lab of Dr. Lucas Parra will present her defense of her research proposal on Tuesday, March 9, 2021 at 9:30am. A copy of her abstract is below. If you would like to attend, please contact Forouzan at fvasheg000@citymail.cuny.edu for the Zoom meeting ID.

Abstract

Transcranial direct current stimulation (tDCS) involves low-intensity electrical current applied to the brain via electrodes placed over the scalp. This technique has gained attention due to putative improvements in brain function and the potential to treat brain-related disorders. Various aspects of tDCS, including safety, simplicity, and affordability, have drawn interest as an alternative treatment. Nonetheless, the efficacy of this technique is open to discussion. An important question about the effectiveness of tDCS is whether its effects can last after the period of stimulation. The lasting effects of this technique are thought to be mediated by synaptic plasticity. Several studies have found DCS-induced effects on synaptic plasticity in animal models. Yet, there is no direct evidence associating neuronal excitability to synaptic plasticity.

One promising application of tDCS is the modulation of motor excitability and motor learning. Functional and structural changes in the primary motor cortex (M1) have been associated with motor skill learning. Therefore, human and animal tDCS studies have targeted this region to modulate motor learning. However, there are ongoing debates about the efficacy of low-intensity tDCS, the underlying mechanism explaining the results, and the importance of online versus offline tDCS with learning. This dissertation provides the first direct in vitro evidence linking the effects of DCS on neuronal membrane potential and excitability to Hebbian synaptic plasticity. While this mechanism now has some support, we also uncovered that it could not fully account for the effects of DCS on plasticity. We propose that DCS also affects plasticity via the propagation of its effects over recurrent excitatory connections combined with a homeostatic plasticity mechanism. We plan to study the effect of anodal tDCS on enhancing motor skill learning in rats in vivo. We will investigate whether the effects are due to sensation or stress. Moreover,