Cross-Sensory Modulation of Primary Sensory Cortex Is Developmentally Regulated by Early Sensory Experience

Abstract

The presence of cross-sensory influences on neuronal responses in primary sensory cortex has been observed previously using several different methods. To test this idea in rat S1 barrel cortex, we hypothesized that auditory stimuli combined with whisker stimulation ("cross-sensory" stimuli) may modify response levels to whisker stimulation. Since the brain has been shown to have a remarkable capacity to be modified by early postnatal sensory activity, manipulating postnatal sensory experiences would be predicted to alter the degree of cross-sensory interactions. To test these ideas, we raised rats with or without whisker deprivation and with or without postnatal exposure to repeated auditory clicks. We recorded extracellular responses under urethane anesthesia from barrel cortex neurons in response to principal whisker stimulation alone, to auditory click stimulation alone, or to a cross-sensory stimulus. The responses were compared statistically across different stimulus conditions and across different rearing groups. Barrel neurons did not generate action potentials in response to auditory click stimuli alone in any rearing group. However, in cross-sensory stimulus conditions the response magnitude was facilitated in the 0 -15 ms post-whisker-stimulus epoch in all rearing conditions, whereas modulation of response magnitude in a later 15-30 ms post-whisker-stimulus epoch was significantly different in each rearing condition. The most significant cross-sensory effect occurred in rats that were simultaneously whisker deprived and click reared. We conclude that there is a modulatory type of cross-sensory auditory influence on normal S1 barrel cortex, which can be enhanced by early postnatal experiences.

Rate and Temporal Coding Convey Multisensory Information in Primary Sensory Cortices

“…2 E ). These temporal differences in unisensory responses are in line with previous results (Wang et al, 2008; Ghoshal et al, 2011) and reflect preprocessing differences along the anatomic pathways (Petersen, 2007; Cruz-Martín et al, 2014). As expected, for both S1 and V1, the shortest response onset was detected in G layers.…”

“…Only few neurons responded differently to bi- versus unimodal stimulation. The high prevalence of additive multisensory neurons confirms previous data showing that multisensory interactions in rodents are modulatory (Ghoshal et al, 2011). In V1, the distribution of PYRs and INs across different classes was similar to S1.…”

Integrative Neuronal Functions in Deafness

“…Such a finding compares well with previous findings demonstrating more uniform poststimulus time histograms in congenitally deaf cats and near absence of long-latency activity (Klinke et al, 1999). Long-latency activity is generally considered a sign of corticocortical interactions (Klinke et al, 1999;Ghoshal et al, 2011) and in this circumstance a sign of functionally deficient corticocortical networks.…”

Developmental neuroplasticity after cochlear implantation

“…Long-latency activity is known to be dependent on corticocortical interactions [102], indicating that deafness impairs corticocortical interactions. This deficit is reversible by chronic electrostimulation with cochlear implants [63].…”