Neuronal activity in primate auditory cortex during the performance of audiovisual tasks

Abstract

This study aimed at a deeper understanding of which cognitive and motivational aspects of tasks affect auditory cortical activity. To this end we trained two macaque monkeys to perform two different tasks on the same audiovisual stimulus and to do this with two different sizes of water rewards. The monkeys had to touch a bar after a tone had been turned on together with an LED, and to hold the bar until either the tone (auditory task) or the LED (visual task) was turned off. In 399 multiunits recorded from core fields of auditory cortex we confirmed that during task engagement neurons responded to auditory and non-auditory stimuli that were task-relevant, such as light and water. We also confirmed that firing rates slowly increased or decreased for several seconds during various phases of the tasks. Responses to non-auditory stimuli and slow firing changes were observed during both the auditory and the visual task, with some differences between them. There was also a weak task-dependent modulation of the responses to auditory stimuli. In contrast to these cognitive aspects, motivational aspects of the tasks were not reflected in the firing, except during delivery of the water reward. In conclusion, the present study supports our previous proposal that there are two response types in the auditory cortex that represent the timing and the type of auditory and non-auditory elements of a auditory tasks as well the association between elements.

Task rule and choice are reflected by layer-specific processing in rodent auditory cortical microcircuits

“…Motor initiation has been reported before to enhance or suppress sensory-driven activity in other (primary) sensory cortices depending on region, system and taskengagement (Busse et al, 2017;Steinmetz et al, 2019). From our data we hypothesize, that, during the detection, the tone-evoked activity in the primary auditory cortex may be modulated by auditory-guided motor initiation (Brosch et al, 2015;Huang et al, 2019;Niwa et al, 2012a). The distinct sound frequency of a pure tone seems less determining on the activity strength.…”

Integration of visual information in auditory cortex promotes auditory scene analysis through multisensory binding

“…properties of a visual stimulus can be exploited to detect correspondence between auditory and 33 visual streams (Crosse et al, 2015;Denison et al, 2013;Rahne et al, 2008), can bias the perceptual 34 organisation of a sound scene (Brosch et al, 2015), and can enhance or impair listening performance 35 depending on whether the visual stimulus is temporally coherent with a target or distractor sound 36 stream (Maddox et al, 2015). Together, these behavioural results suggest that temporal coherence 37 between auditory and visual stimuli can promote binding of cross--modal features to enable the 38 formation of an auditory--visual (AV) object (Bizley et al, 2016b).…”

Neuronal correlates of auditory streaming in the auditory cortex of behaving monkeys

“…Thus, our approach potentially has a confound similar to that of all previous studies on neurophysiological correlates of auditory streaming in mammals, in which different auditory percepts were induced with different (auditory) stimulations (Fishman et al., ; Kanwal, Medvedev, & Micheyl, ; Micheyl, Tian, Carlyon, & Rauschecker, ; Scholes, Palmer, & Sumner, ). Indeed, in contrast to the traditional view of primary auditory cortex as a unisensory brain structure (Brosch & Scheich, ), there is converging evidence in different species that some auditory cortical neurons respond to visual stimuli (Bizley, Nodal, Bajo, Nelken, & King, ; Brosch et al., , ; Li et al., ), or that their auditory responses are modulated by concurrent visual stimuli (Bizley et al., ; Falchier, Clavagnier, Barone, & Kennedy, ; Kayser, Petkov, & Logothetis, ; Schroeder & Foxe, ; Schroeder & Lakatos, ). Despite these observations we can rule out that the variations in response ratio observed here resulted merely from comparing neuronal responses to different sensory stimuli.…”

“…With the aid of a bootstrap analysis, we assessed whether the amplitude of a target frequency was significantly ( p < 0.001) greater than the corresponding value of the amplitude spectrum of surrogate PSTHs. For the latter, we generated 10,000 simulated spike trains that had the same mean firing rate as the original spike train but with randomly distributed interspike intervals (as in Brosch et al., ). In the visual condition, the target frequencies were 2.78 and 4.17 Hz in monkey W and monkey E (corresponding to flash periods of 360 and 240 ms), respectively, and 2.38 and 3.57 Hz in monkey C (corresponding to flash periods of 420 and 280 ms).…”

“…We focused on primary auditory cortex because the original observations on neuronal correlates of auditory stream formation were made in this part of auditory cortex (Fishman et al., ). This area is also known to be affected by visual stimuli (Brosch, Selezneva, & Scheich, , ; Schroeder & Lakatos, ). Here we report results from experiments that were optimized to compare response ratios when the perceptual organization of the tone sequence was modified by the flash sequences.…”