Hannover Medical School, Institute of AudioNeuroTechnology and Department of Experimental Otology of the ENT Clinics, Hannover, Germany; Faculty of Medicine University of Indonesia, Department of Medical Physiology and Biophysics / Medical Technology IMERI, Jakarta, Indonesia.
Hannover Medical School, Institute of AudioNeuroTechnology and Department of Experimental Otology of the ENT Clinics, Hannover, Germany.
Hear Res. 2024 Aug;449:109032. doi: 10.1016/j.heares.2024.109032. Epub 2024 May 17.
Neurons within a neuronal network can be grouped by bottom-up and top-down influences using synchrony in neuronal oscillations. This creates the representation of perceptual objects from sensory features. Oscillatory activity can be differentiated into stimulus-phase-locked (evoked) and non-phase-locked (induced). The former is mainly determined by sensory input, the latter by higher-level (cortical) processing. Effects of auditory deprivation on cortical oscillations have been studied in congenitally deaf cats (CDCs) using cochlear implant (CI) stimulation. CI-induced alpha, beta, and gamma activity were compromised in the auditory cortex of CDCs. Furthermore, top-down information flow between secondary and primary auditory areas in hearing cats, conveyed by induced alpha oscillations, was lost in CDCs. Here we used the matching pursuit algorithm to assess components of such oscillatory activity in local field potentials recorded in primary field A1. Additionally to the loss of induced alpha oscillations, we also found a loss of evoked theta activity in CDCs. The loss of theta and alpha activity in CDCs can be directly related to reduced high-frequency (gamma-band) activity due to cross-frequency coupling. Here we quantified such cross-frequency coupling in adult 1) hearing-experienced, acoustically stimulated cats (aHCs), 2) hearing-experienced cats following acute pharmacological deafening and subsequent CIs, thus in electrically stimulated cats (eHCs), and 3) electrically stimulated CDCs. We found significant cross-frequency coupling in all animal groups in > 70% of auditory-responsive sites. The predominant coupling in aHCs and eHCs was between theta/alpha phase and gamma power. In CDCs such coupling was lost and replaced by alpha oscillations coupling to delta/theta phase. Thus, alpha/theta oscillations synchronize high-frequency gamma activity only in hearing-experienced cats. The absence of induced alpha and theta oscillations contributes to the loss of induced gamma power in CDCs, thereby signifying impaired local network activity.
神经元网络中的神经元可以通过神经元振荡的同步性，根据自上而下和自下而上的影响进行分组。这就从感觉特征中创建了感知对象的表示。振荡活动可以分为刺激相位锁定（诱发）和非相位锁定（诱导）。前者主要由感觉输入决定，后者由更高层次（皮质）处理决定。使用人工耳蜗（CI）刺激研究了先天性耳聋猫（CDC）中听觉剥夺对皮质振荡的影响。在 CDC 的听觉皮层中，CI 诱导的 alpha、beta 和 gamma 活动受损。此外，在听力猫中，由诱导 alpha 振荡传递的次级和初级听觉区域之间的自上而下信息流在 CDC 中丢失。在这里，我们使用匹配追踪算法来评估初级场 A1 中记录的局部场电位的这种振荡活动的成分。除了诱导 alpha 振荡的丢失之外，我们还发现 CDC 中的诱发 theta 活动也丢失了。CDC 中 theta 和 alpha 活动的丢失可以直接与由于交叉频率耦合导致的高频（gamma 波段）活动减少相关。在这里，我们在成年 1）有听觉经验、声学刺激的猫（aHCs），2）有听觉经验、急性药理学失聪后和随后的 CI 的猫（eHCs），以及 3）电刺激的 CDC 中量化了这种交叉频率耦合。我们在所有动物组中超过 70%的听觉反应部位都发现了显著的交叉频率耦合。在 aHCs 和 eHCs 中，主要的耦合是 theta/alpha 相位和 gamma 功率之间的耦合。在 CDC 中，这种耦合丢失了，被 alpha 振荡耦合到 delta/theta 相位所取代。因此，只有在有听觉经验的猫中，alpha/theta 振荡才会同步高频 gamma 活动。诱导 alpha 和 theta 振荡的缺失导致 CDC 中诱导 gamma 功率的丢失，从而表明局部网络活动受损。
