Balanced Noise-Evoked Excitation and Inhibition in Awake Mice CA3

Abstract

The hippocampus is known as a neuronal structure involved in learning, memory and spatial navigation using multi-sensory cues. However, the basic features of its response to acoustic stimuli without any behavioral tasks (conditioning) remains poorly studied. Here, we investigated the CA3 response to auditory stimuli using in vivo loose-patch recordings in awake and anesthetized C57 mice. Different acoustic stimuli in addition to broadband noise such as click, FM sound and pure tone were applied to test the response of CA3 in awake animals. It was found that the wakefulness of the animal is important for the recorded neurons to respond. The CA3 neurons showed a stronger response to broadband noise rather than the other type of stimuli which suggested that auditory information arrived at CA3 via broadband pathways. Finally, we investigated the excitatory and inhibitory inputs to CA3 neurons by using in vivo whole-cell voltage-clamp techniques with the membrane potential holding at −70 and 0 mV, respectively. In awake animals, the excitatory and inhibitory inputs CA3 neurons receive induced by noise are balanced by showing stable intervals and proportional changes of their latencies and peak amplitudes as a function of the stimulation intensities.

Increased hippocampal GABAergic inhibition after long-term high-intensity sound exposure

“…This pathway is implicated in the formation of long-term auditory memories [10], and auditory cues can be used in the formation of spatial memories [11]. Hippocampal place cells can be activated by a task using auditory dimension cues [12] and recently it was demonstrated that sound stimulation evoke excitatory and inhibitory currents in CA3 pyramidal neurons in vivo [13].…”

Mechanisms of high-intensity sound exposure on inhibiting hippocampal long-term potentiation: role of brain-derived neurotrophic factor

“…We found increased c-fos expression in the pyramidal layer, were the glutamatergic pyramidal neurons are located, however we cannot discard the activation of GABAergic interneurons located in the pyramidal layer or adjacent to it. Interestingly, in vivo hippocampal recordings showed that sound exposure evokes inhibitory currents on pyramidal neurons, accordingly to the activation of hippocampal inhibitory interneurons (Wang et al, 2017).…”

“…The hippocampus receives sensory information from several modalities, which are fundamental for its role in spatial navigation, learning and memory formation (Save et al, 2000;Jeffery, 2007;Ravassard et al, 2013). It is connected to the auditory system (Kraus and Canlon, 2012;Zhang et al, 2018) and sound stimulation triggers excitatory and inhibitory neurotransmission in hippocampal neurons in vivo (Wang et al, 2017). Also, the hippocampus is related to the formation of auditory memories (Squire et al, 2001), it uses auditory information for the formation of spatial memory (Tamura et al, 1990) and hippocampal place cells can be activated by auditory dimension cues (Aronov et al, 2017).…”

Impacto da estimulação sonora de alta intensidade na plasticidade sináptica de longo prazo e na neurotransmissão hipocampal

“…Abe e colaboradores em 2014 já haviam demostrado que neurônios piramidais registrados in vivo no modo wholle cell patch clamp apresentaram hiperpolarização concomitante a estimulação com tons puros com 110 dB durante 300 ms em intervalos de 6-8 segundos. Além disso, registros in vivo em animais acordados mostraram que a estimulação sonora produz correntes sináptica inibitórias e excitatórias em neurônios piramidais da região CA3 do hipocampo (Wang et al, 2017) demostrando a responsividade direta do hipocampo a estimulação auditiva.…”