We investigated the representation of four typical guinea pig vocalizations in the auditory cortex (AI) in anesthetized guinea pigs with the aim to compare cortical data to the data already published for identical calls in subcortical structures - the inferior colliculus (IC) and medial geniculate body (MGB). Like the subcortical neurons also cortical neurons typically responded to many calls with a time-locked response to one or more temporal elements of the calls. The neuronal response patterns in the AI correlated well with the sound temporal envelope of chirp (an isolated short phrase), but correlated less well in the case of chutter and whistle (longer calls) or purr (a call with a fast repetition rate of phrases). Neuronal rate vs. characteristic frequency profiles provided only a coarse representation of the calls' frequency spectra. A comparison between the activity in the AI and those of subcortical structures showed a different transformation of the neuronal response patterns from the IC to the AI for individual calls: i) while the temporal representation of chirp remained unchanged, the representations of whistle and chutter were transformed at the thalamic level and the response to purr at the cortical level; ii) for the wideband calls (whistle, chirp) the rate representation of the call spectra was preserved in the AI and MGB at the level present in the IC, while in the case of low-frequency calls (chutter, purr), the representation was less precise in the AI and MGB than in the IC; iii) the difference in the response strength to natural and time-reversed whistle was found to be smaller in the AI than in the IC or MGB.

• MeSH
• Acoustic Stimulation MeSH
• Species Specificity MeSH
• Guinea Pigs MeSH
• Neurons physiology   MeSH
• Evoked Potentials, Auditory MeSH
• Auditory Cortex physiology   MeSH
• Vocalization, Animal physiology   MeSH
• Animals MeSH
• Check Tag
• Guinea Pigs MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Individual nuclei of the auditory pathway contribute in a specific way to the processing of complex acoustical signals. We investigated the responses of single neurons to typical guinea pig vocalizations (purr, chutter, chirp and whistle) in the ventral part of the medial geniculate body (MGB) of anesthetized guinea pigs. The neuronal and population peristimulus time histograms (PSTHs) reflected the repetition frequency of individual phrases in the calls. The patterns of PSTHs correlated well with the sound temporal envelope in calls with short phrases (purr, chirp). The dominant onset character of the neuronal responses resulted in a lower correlation between the sound envelope and the PSTH pattern in the case of longer calls (chutter and whistle). A time-reversed version of whistle elicited on average a 13% weaker response than did the natural whistle. The rate-characteristic frequency (CF) profile provided only a coarse representation of the sound frequency spectrum without detailed information about the individual spectral peaks and their relative magnitudes. In comparison with the inferior colliculus (Suta et al. in J Neurophysiol 90:3794-3808, 2003), the processing of species-specific vocalizations in the MGB differs in: (1) a less precise representation of the temporal envelope in the case of longer calls, but not in the case of calls consisting of one or more short phrases; (2) a less precise rate-CF representation of the spectral envelope in the case of low-frequency calls, but not in the case of broad-band calls; (3) a smaller difference between the responses to natural and time-reversed whistle.

• MeSH
• Action Potentials physiology   MeSH
• Acoustic Stimulation MeSH
• Time Factors MeSH
• Species Specificity MeSH
• Geniculate Bodies cytology   physiology   MeSH
• Guinea Pigs MeSH
• Neurons physiology   MeSH
• Reaction Time physiology   MeSH
• Auditory Perception physiology   MeSH
• Spectrum Analysis MeSH
• Vocalization, Animal physiology   MeSH
• Dose-Response Relationship, Radiation MeSH
• Animals MeSH
• Check Tag
• Guinea Pigs MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH