Crossmodal Induction of Thalamocortical Potentiation Leads to Enhanced Information Processing in the Auditory Cortex

Abstract

Summary Sensory systems do not work in isolation; instead they show interactions that are specifically uncovered during sensory loss. To identify and characterize these interactions, we investigated whether visual deprivation leads to functional enhancement in primary auditory cortex (A1). We compared sound-evoked responses of A1 neurons in visually-deprived animals to those from normally-reared animals. Here we show that visual deprivation leads to improved frequency selectivity as well as increased frequency and intensity discrimination performance of A1 neurons. Furthermore, we demonstrate in vitro that in adults, visual deprivation strengthens thalamocortical (TC-) synapses in A1, but not in primary visual cortex (V1). Because deafening potentiated TC-synapses in V1 but not A1, cross-modal TC-potentiation seems to be a general property of adult cortex. Our results suggest that adults retain the capability for cross-modal changes while such capability is absent within a sensory modality. Thus multimodal training paradigms might be beneficial in sensory processing disorders.

Shape Perception and Navigation in Blind Adults

“…Psychophysical evidence suggests that some tactile and audio skills in congenital blind individuals result enhanced (e.g., Lessard et al, 1998; Roder et al, 1999; Goldreich and Kanics, 2003; Gougoux et al, 2004; Tinti et al, 2006; Fortin et al, 2008), such as the ability to localize a sound source in the horizontal plane (Lessard et al, 1998; Gougoux et al, 2004; Doucet et al, 2005) or discriminate between different sounds (Gougoux et al, 2004). Studies of animals confirm this view by suggesting that sound processed by neurons in auditory cortical areas can be enhanced following visual deprivation (Korte and Rauschecker, 1993; Petrus et al, 2014). …”

Cross-Modality Sharpening of Visual Cortical Processing through Layer-1-Mediated Inhibition and Disinhibition

“…As such, barely detectable images of predators in a dim environment may be better perceived by rodents when there are sounds coincidentally associated with the threats. Arising from the current results are several intriguing questions: how this top-down circuit is formed during development; whether it is hardwired or if it can be shaped by visual or auditory experience (Petrus et al, 2014; Petrus et al, 2015). Studying the A1-V1 circuit in the developing brain of both naïve and experientially manipulated animals will thus be an exciting future research direction.…”

Intracortical Circuits in Thalamorecipient Layers of Auditory Cortex Refine after Visual Deprivation

“…Because thalamorecipient layer 4 (L4) cells receive input from the superficial layers (Barbour and Callaway, 2008; Kratz and Manis, 2015), multisensory inputs might thus sculpt circuits in thalamorecipient layers. Indeed, after the critical period, depriving mice of vision by dark exposure (DE) for ∼ 1 week alters the sound-evoked responses in layer 4 (L4) of primary auditory cortex (A1; Petrus et al, 2014). L4 cells responded more robustly to sounds, consistent with increased thalamocortical transmission after DE (Petrus et al, 2014).…”

“…Indeed, after the critical period, depriving mice of vision by dark exposure (DE) for ∼ 1 week alters the sound-evoked responses in layer 4 (L4) of primary auditory cortex (A1; Petrus et al, 2014). L4 cells responded more robustly to sounds, consistent with increased thalamocortical transmission after DE (Petrus et al, 2014). L4 neurons also showed increased frequency selectivity (Petrus et al, 2014).…”