Interrogation of Thalamocortical Circuits during Ketamine/Xylazine-Induced Slow-Waves with High-Resolution Electrophysiological Methods
Horváth Csaba Gyula
János Szentágothai Neurosciences
Dr. Bereczki Dániel
MTA TTK földszinti kis előadóterem
2025-01-30 10:00:00
Dr. Fiáth Richárd
Dr. Ujma Przemyslaw Péter
Dr. Slézia Andrea
Dr. Bereczki Dániel
Dr. Szalárdy Orsolya
Dr. Horváth Domonkos
Recent studies have shown that slow-waves (SWs), prominent during anesthesia and deep sleep,
shows complex dynamics and propagate across neocortical areas. However, it is unclear if similar
propagation occurs within the thalamus. This dissertation explores the propagation of population
activity within the thalamus of ketamine/xylazine-anesthetized rats and mice, using high-density
silicon probes. Propagating activity is predominantly detected in dorsal thalamic nuclei, including
the posterior (Po), lateral posterior (LP), and laterodorsal (LD) nuclei. Activity most of the time
propagate along the dorsoventral axis, with over half of the upstates showing ventral-to-dorsal
propagation. Simultaneous recordings from the neocortex and thalamus under anesthesia revealed
a weak but noticeable correlation between cortical and thalamic propagation patterns. In vivo
recordings from naturally sleeping rats showed propagating activity patterns in the thalamus during
slow-wave sleep, but they exhibited patterns with a lower frequency and faster propagation than
those under anesthesia. These findings suggest that spontaneous population activity propagation is
intrinsic to the thalamocortical network during synchronized brain states like deep sleep or
anesthesia. This research could contribute to a deeper understanding of these states as intricate
neural processes. Subsequent studies should examine how different anesthetics influence
thalamocortical activity and the distinct functions of various thalamic nuclei across different brain
states. Analyzing single-unit activities from each thalamic nucleus might offer valuable insights
into some of the unresolved questions.
A significant limitation in neuroscience is the scarcity of publicly available high-resolution neural
recordings. This thesis also presents a dataset recorded from the neocortex of twenty rats
anesthetized with ketamine/xylazine. The dataset contains raw neural recordings, spike times,
extracellular spike waveforms, and unit properties in a standardized format. We provide technical
validation, presenting distributions of derived unit properties and various spike sorting quality
metrics. This dataset offers numerous benefits, such as facilitating detailed analyses of neuronal
firing patterns, aiding neuron classification, and serving input for spike-sorting algorithms and data
processing methods. Additionally, it may be used to investigate laminar-specific neuronal activity
during slow oscillations.
