Spatio-temporal components of stimulus-related activity in the inferior colliculus

Dominika Lyzwa, Dmitry Bibichkov, Hugh H Lim, J. Michael Herrmann

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The inferior colliculus (IC) is an important stage in the auditory processing pathway. Understanding its encoding mechanism is currently specifically relevant since the IC has become a target for auditory prosthesis (Auditory Midbrain Implant - AMI). Knowledge of the spatio-temporal encoding taking place in the IC would enable development of an algorithm for mapping auditory signals onto 3d electric stimulation patterns. This could help to improve the acoustic perception in AMI-patients. We analyzed multi-unit activity recorded from the IC in cats during acoustic stimulation with pure tones of varying frequency and intensity. Multi-dimensional data were studied using principal and independent component analysis. We studied the correlations between these components and the raw traces with respect to the stimulus parameters. The recordings were classified into stimulus categories using linear discriminant analysis. The first components, contributing most to the variance of the data and characterizing most significant neural activity were sufficient to verify the tonotopic arrangement of the IC [see figure 1]. Separability of neural responses into stimulus classes depended critically on the filter range used for preprocessing. While low-frequency bands of the response carried information about the stimulus parameters, frequency bands above 1 kHz did not improve the classification. Furthermore, the separability varied strongly for different time windows within the time course of the neural response. For a time window starting 5-10 ms after stimulus onset the classification performance was optimal, indicating the short latency of neural response in the IC. We found that the classification performance was also affected by the position of the recording site along the tonotopic axis in the IC, and observed a higher information density in layers best responsive for middle stimulus-frequencies. Components obtained by PCA of multiunit activity reflect the tonotopic organization of the feline IC. Furthermore, the information is mostly contained in the first component of the response and at early latencies. Figure 1. Each bin shows the projection of the neural response obtained for a specific stimulus frequency in one channel onto the first component obtained by PCA. Best correlation for different stimulus-frequencies varies systematically with electrode position. The channels are aligned linearly along the tonotopic arrangement of the IC, with channel 1 and 32 recording in the layer most responsive for high and respectively low frequencies.
Original languageEnglish
JournalFrontiers in Computational Neuroscience
Issue number135
DOIs
Publication statusPublished - 2010

Fingerprint

Dive into the research topics of 'Spatio-temporal components of stimulus-related activity in the inferior colliculus'. Together they form a unique fingerprint.

Cite this