Brain sensory processing is not passive, but is rather modulated by our internal state. Different research methods such as non-invasive imaging methods and intracranial recording of the local field potential (LFP) have been used to study to what extent sensory processing and the auditory cortex in particular are modulated by selective attention. However, at the level of the single- or multi-units the selective attention in humans has not been tested. In addition, most previous research on selective attention has explored externally-oriented attention, but attention can be also directed inward (i.e., internal attention), like spontaneous self-generated thoughts and mind-wandering. In the present study we had a rare opportunity to record multi-unit activity (MUA) in the auditory cortex of a patient. To complement, we also analyzed the LFP signal of the macro-contact in the auditory cortex. Our experiment consisted of two conditions with periodic beeping sounds. The participants were asked either to count the beeps (i.e., an “external attention” condition) or to recall the events of the previous day (i.e., an “internal attention” condition). We found that the four out of seven recorded units in the auditory cortex showed increased firing rates in “external attention” compared to “internal attention” condition. The beginning of this attentional modulation varied across multi-units between 30–50 msec and 130–150 msec from stimulus onset, a result that is compatible with an early selection view. The LFP evoked potential and induced high gamma activity both showed attentional modulation starting at about 70–80 msec. As the control, for the same experiment we recorded MUA activity in the amygdala and hippocampus of two additional patients. No major attentional modulation was found in the control regions. Overall, we believe that our results provide new empirical information and support for existing theoretical views on selective attention and spontaneous self-generated cognition.
|Number of pages||20|
|State||Published - Dec 2022|
Bibliographical noteFunding Information:
We thank the patients for participating in this study. This study was supported by an Alon Fellowship for outstanding young faculty members by the Israeli Council for Higher Education ( VA ), and the program “Investissements d'avenir” ANR-10-IAIHU-06 and the ICM-OCIRP. We thank three anonymous reviewers for their insightful comments. The authors declare no competing interests.
© 2022 Elsevier Ltd
- Auditory cortex
- Early selection
- Internal attention
- Multi-unit (MUA) recording in humans
- Selective attention