Intracortical processing and psychophysical detectability of electrically evoked single-neuron activity

• Applicant: Professor Dr. Maik C. Stüttgen
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: from 2016 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 315227418

In contrast to the long-standing notion that the role of any single brain cell for neural processing is vanishingly small, recent studies have demonstrated that electrical activation of only one cortical neuron can have measurable effects on global brain state, movement, and perception. However, it is largely unknown how single-neuron spiking triggers the cascade of activity which eventually leads to the observed phenomena. Here, I propose two experiments to begin to elucidate some of the processes involved in translating electrically induced single-neuron activity in somatosensory cortex to perception. In the first experiment, the effect of single-neuron spiking parameters (patterning of action potential output) on nearby neurons will be investigated. To that end, the spiking activity of multiple neurons will be recorded across all layers of somatosensory cortex using multi-electrode arrays (silicon probes) while precisely controlling one individual neuron's spiking activity. Recent advances in the methodology of nanostimulation allow to reliably evoke arbitrary patterns of spiking in single neurons, with a temporal jitter of induced actions potentials in the range of only 0.5 ms. Systematic parametric variation of spike patterns with concomitant multiple unit recordings will answer the question which kind of activity pattern in which type of neuron in a given cortical layer exerts an effect on local network activity. In the second experiment, a subset of effective and ineffective spike patterns identified in Experiment 1 will be tested in awake animals trained to report electrical neuron activation in a psychophysical detection task. It is hypothesized that efficacy of a given stimulation configuration (spiking pattern, cell type, and cortical layer) determined in Experiment 1 is predictive of psychophysical efficacy in Experiment 2. The data obtained on the spatiotemporal spread of induced single-cell activity across layers and columns will yield novel insights into intracortical processing and can be used as a benchmark for biologically inspired artificial neural networks of cortical columns.

• DFG Programme: Research Grants