Asymmetrical representation of auditory space in human cortex

The effect of spatial adaptation on auditory motion processing

“…Quite different from superior colliculus, the occurrence of a place code at cortical levels of the mammalian brain seems questionable (e.g., McAlpine et al, 2001). For the human auditory cortex, an alternative model has been proposed in which the auditory space is represented by a population rate code of two opponent, widely distributed populations of neurons, one preferentially activated by sound sources to the left and the other by those to the right of the listener (Salminen et al, 2010). Independently of the question of space coding, it is important to note that the location-specific adaptation described by Salminen et al (2010) may play a role in motion processing after motiononset delay, as in the experimental paradigm employed here.…”

“…For the human auditory cortex, an alternative model has been proposed in which the auditory space is represented by a population rate code of two opponent, widely distributed populations of neurons, one preferentially activated by sound sources to the left and the other by those to the right of the listener (Salminen et al, 2010). Independently of the question of space coding, it is important to note that the location-specific adaptation described by Salminen et al (2010) may play a role in motion processing after motiononset delay, as in the experimental paradigm employed here. Using an adaptation paradigm in which pairs of adaptor and probe sounds were presented, Salminen et al (2010) observed that the N1m response to the probe sound in one hemispace was more strongly attenuated when the preceding adaptor sound was in the same hemispace than when adaptor and probe sounds were in different hemispaces.…”

“…Whether comparable processes exist also in cortex is, on the one hand, debatable since a place code for auditory space, composed of location-tuned neurons, has so far not been found in cortical structures. On the other hand, in the human cortex, evidence of location-specific adaptation effects was provided by a recent MEG study revealing that the N1m response to a probe sound is substantially attenuated by a preceding adaptor sound presented in the same hemispace as the probe (Salminen et al, 2010). Using MEG, location-specific adaptation was also found in a task in which listeners attended to sound location; these featurespecific attention effects may arise from enhanced tuning of receptive fields of task-relevant neuronal populations (Ahveninen et al, 2006).…”

“…The rationale was that our hypothesis described above implied the involvement of location-specific ("stationary") neurons in the emergence of adaptation, but did not necessarily require the assumption of motion-specific neurons, that is, neurons exhibiting a preference for a specific direction of motion while being insensitive to stationary sound. Even though for the human auditory system the existence of specific motion sensitivity remains still a matter of debate (for further discussion, see Smith et al, 2004Smith et al, , 2007, single subcortical and cortical cells showing such response properties have been found in animal studies (e.g. Spitzer and Semple, 1991;Moiseff and Haresign, 1992).…”

Neuroplasticity-targeted Intervention for Idiopathic Sudden Sensorineural Hearing Loss: A New Therapeutic Direction

“…In that study, the hearing recovery of the CIST+SCT group far exceeded that of the SCT group. They also used MEG to analyze the neural activity of six patients from the CIST+SCT group, focusing on the following types of neural activity: N1m response (generated mainly in the belt and parabelt areas of the auditory cortex) [76] and the auditory steady state response (generated in the primary auditory cortex) [77]. They found that monaural stimulation induced contralateral dominance, which is indicative of normal hearing.…”