Location of cells giving phase-locked responses to pure tones in the primary auditory cortex.
Phase-locked responses to pure tones have previously been described in the primary auditory cortex (AI) of the guinea pig. They are interesting because they show that some cells may use a temporal code for representing sounds of 60-300 Hz rather than the rate or place mechanisms used over most of AI. Our previous study had shown that the phase-locked responses were grouped together, but it was not clear whether they were in separate minicolumns or a larger macrocolumn. We now show that the phase-locked cells are arranged in a macrocolumn within AI that forms a subdivision of the isofrequency bands. Phase-locked responses were recorded from 158 multiunits using silicon based multiprobes with four shanks. The phase-locked units gave the strongest response in layers III/IV but phase-locked units were also recorded in layers II, V and VI. The column included cells with characteristic frequencies of 80 Hz-1.3 kHz (0.5-0.8 mm long) and was about 0.5 mm wide. It was located at a constant position at the intersection of the coronal plane 1 mm caudal to bregma and the suture that forms the lateral edge of the parietal bone.
Wallace
M N
MN
MRC Institute of Hearing Research, University Park, Nottingham NG7 2RD, UK. markw@ihr.mrc.ac.uk
Coomber
B
B
Sumner
C J
CJ
Grimsley
J M S
JM
Shackleton
T M
TM
Palmer
A R
AR
D000161:Acoustic Stimulation; D000818:Animals; D001299:Audiometry / Q000379:methods*; D001303:Auditory Cortex / Q000166:cytology / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D004566:Electrodes; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006168:Guinea Pigs; D006309:Hearing; D008297:Male; D008954:Models, Biological; D009474:Neurons / Q000502:physiology; D013788:Thalamus / Q000502:physiology; D013997:Time Factors