1. Click train elicited local gamma synchrony: differing performance and pharmacological responsivity of primary auditory and prefrontal cortices.
- Author
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Gautam D, Shields A, Krepps E, Ummear Raza M, and Sivarao DV
- Subjects
- Animals, Female, Rats, Excitatory Amino Acid Antagonists pharmacology, Auditory Perception physiology, Auditory Perception drug effects, Electroencephalography methods, Prefrontal Cortex physiology, Prefrontal Cortex drug effects, Auditory Cortex physiology, Auditory Cortex drug effects, Rats, Sprague-Dawley, Dizocilpine Maleate pharmacology, Gamma Rhythm drug effects, Gamma Rhythm physiology, Acoustic Stimulation methods, Evoked Potentials, Auditory drug effects, Evoked Potentials, Auditory physiology
- Abstract
Auditory neural networks in the brain naturally entrain to rhythmic stimuli. Such synchronization is an accessible index of local network performance as captured by EEG. Across species, click trains delivered ∼ 40 Hz show strong entrainment with primary auditory cortex (Actx) being a principal source. Imaging studies have revealed additional cortical sources, but it is unclear if they are functionally distinct. Since auditory processing evolves hierarchically, we hypothesized that local synchrony would differ between between primary and association cortices. In female SD rats (N = 12), we recorded 40 Hz click train-elicited gamma oscillations using epidural electrodes situated at two distinct sites; one above the prefrontal cortex (PFC) and another above the Actx, after dosing with saline (1 ml/kg, sc) or the NMDA antagonist, MK801 (0.025, 0.05 or 0.1 mpk), in a blocked crossover design. Post-saline, both regions showed a strong 40 Hz auditory steady state response (ASSR). The latencies for the N1 response were ∼ 16 ms (Actx) and ∼ 34 ms (PFC). Narrow band (38-42 Hz) gamma oscillations appeared rapidly (<40 ms from stim onset at Actx but in a more delayed fashion (∼200 ms) at PFC. MK801 augmented gamma synchrony at Actx while dose-dependently disrupting at the PFC. Event-related gamma (but not beta) coherence, an index of long-distance connectivity, was disrupted by MK801. In conclusion, local network gamma synchrony in a higher order association cortex performs differently from that of the primary auditory cortex. We discuss these findings in the context of evolving sound processing across the cortical hierarchy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)
- Published
- 2024
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