Corticocortical Interactions between and within Three Cortical Auditory Areas Specialized for Time-Domain Signal Processing

Abstract

In auditory cortex of the mustached bat, the FF (F means frequency modulation), dorsal fringe (DF), and ventral fringe (VF) areas consist of "combination-sensitive" neurons tuned to the pair of an emitted biosonar pulse and its echo with a specific delay (best delay: BD). The DF and VF areas are hierarchically at a higher level than the FF area. Focal electric stimulation of the FF area evokes "centrifugal" BD shifts of DF neurons, i.e., shifts away from the BD of the stimulated FF neurons, whereas stimulation of the DF neurons evokes "centripetal" BD shifts of FF neurons, i.e., shifts toward the BD of the stimulated DF neurons. In our current studies, we found that the feedforward projection from FF neurons evokes centrifugal BD shifts of VF neurons, that the feedback projection from VF neurons evokes centripetal BD shifts of FF neurons, that the contralateral projection from DF neurons evokes centripetal BD shifts of DF neurons, and that the centripetal BD shifts evoked by the DF and VF neurons are 2.5 times larger than the centrifugal BD shifts evoked by the FF neurons. The centrifugal BD shifts shape the selective neural representation of a specific target distance, whereas the centripetal BD shifts expand the representation of the selected specific target distance to focus on the processing of the target information at a specific distance. The centrifugal and centripetal BD shifts evoked by the feedforward and feedback projections promote finer analysis of a target at shorter distances.

Tuning shifts of the auditory system by corticocortical and corticofugal projections and conditioning

“…(g) The block diagram showing the projections evoking the centripetal (arrow) or centrifugal (line with a short bar at its end) BDe shifts. The short dashed lines indicate either centripetal or centrifugal BDe shifts that are speculated (Tang and Suga 2009). …”

“…5e). In other words, lateral, contralateral, feedforward and/or feedback modulations by the FF area are centrifugal but those of the DF area are centripetal (Xiao and Suga 2004; Tang et al 2007; Tang and Suga 2008, 2009). In addition, it has also been known that feedback modulation of the VF area to the FF area is centripetal (Fig.…”

Post-spike hyperpolarization participates in the formation of auditory behavior-related response patterns of inferior collicular neurons in Hipposideros pratti

“…For example, the CF-CF and FM-FM areas in the auditory cortex (AC) process the flying velocity and target range information, respectively (Suga, 1990(Suga, , 1994Xiao and Suga, 2004;Tang and Suga, 2009). These function areas could also be found in the inferior colliculus (IC) (Olsen and Suga, 1991;Mittmann and Wenstrup, 1995;Ma and Suga, 2008).…”

Low-Intensity Ultrasound Causes Direct Excitation of Auditory Cortical Neurons

“…The effects of US stimulation on auditory cortical neurons were examined in primary neuron cultures. Cultures of primary cortical neurons were prepared from the mouse auditory cortex on embryonic day (E) 17 [ 32 , 33 ]. Dissected cells were cultured in neurobasal medium for at least 14 days to remove the neuroglial cells.…”