Postersession 3
Poster #: 93
Topic: Neuronal models
Friday, Sep 11, 2015
1st floor

Topographic distribution of stimulus-specific adaptation in the rat auditory cortex

Javier Nieto1 & Manuel S. Malmierca2

1Auditory Neurophysiology Laboratory, Institute of Neuroscience of Castilla y León (INCyL), University of Salamanca, Salamanca, Spain
2Cellular Biology and Pathology, University of Salamanca, Salamanca, Spain

SSA is known to be a widespread property of neurons in the primary auditory cortex (AC Ulanovsky et. al, 2003), but its anatomical distribution remains unexplored. The present study aims at characterizing the distribution of SSA in the rat AC.

Multiunit activity to pure tone stimulation was collected across the whole AC of anesthetized rats under an oddball paradigm (deviant probability: 10%, frequency contrast: 0.5 octaves, interstimulus interval: 300 ms). Stereotaxic coordinates were determined for each electrode penetration, and the limits between the putative fields were outlined for each animal using the characteristic frequency gradient as the main reference landmark.

Our results show that SSA is topographically distributed throughout the AC (Topological product statistic, C=0.32, p<0.01). Specifically, median CSI was lowest in the primary fields A1 (0.49) and AAF (0.56) and highest in secondary fields SRAF (0.75) and PAF (0.72) (Kruskal-Wallis test, p<1e-6). These differences are present throughout the whole neural response, and are due to differential adaptation to the standard stimuli. Moreover, this adaptation was faster in secondary fields, where the response to the standard quickly reaches a steady state of virtually no response.

In conclusion, A1 is confirmed to be the first station in the lemniscal auditory pathway where SSA is present, but neurons in the non-primary fields are much more sensitive to repetition as they completely filter out repetitive stimuli, thus enhancing the contrast between deviant and standard.

Supported Spanish-MINECO(BFU2013-43608) and JCYL(SA343U14) to MSM and a JCYL- fellowship(ERIDI2007-2013) to JN.