Sequence Sensitivity of Neurons in Cat Primary Auditory Cortex

Coleman Laboratory, W.M. Keck Center for Integrative Neuroscience, University of California at San Francisco, San Francisco, CA 94143-0732, USA.
Cerebral Cortex (Impact Factor: 8.67). 01/2001; 10(12):1155-67. DOI: 10.1093/cercor/10.12.1155
Source: PubMed


Properties of sequence-sensitive neurons in primary auditory cortex of cats were explored in detail. Stimuli were sequences of two tones, in which the frequency and intensity of the first tone and the temporal separation between the first and second, or probe, tone were parametrically varied. After presentation of the first tone, the responses of 32 single units and 48 multiunits to the probe tone were found to be enhanced up to 140-5270% (median 340%) above the response obtained in the single-tone condition. Probe tone enhancement was induced from a considerable number of sequence conditions and depended on the frequency and intensity of the first tone and on the temporal separation between the onsets of the first and the probe tone. On average, the maximally enhanced response occurred when the first tone was 1 octave below or above the probe tone and its intensity was 14 dB louder than the probe tone. The most effective temporal separation of the tones for an enhancement effect was approximately 100 ms. The range of enhancing tones was largely outside the excitatory tuning curve of a neuron. Results extend previous findings of properties of sequence-sensitive neurons in the auditory cortex of echolocating bats and non-echolocating mammals, and suggest that sequence-sensitive neurons are quite common and involved in the cortical representation of spectrotemporal patterns of acoustic signals.

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    • "Neuroimaging studies have demonstrated that multiple cortical regions are involved in temporal sequence processing (Clegg et al., 1998; Mauk and Buonomano, 2004). Recent neurophysiology studies have shown that even neurons in primary visual cortex can learn to recognize and predict spatiotemporal sequences (Xu et al., 2012; Gavornik and Bear, 2014) and that neurons in primary visual and auditory cortex exhibit sequence sensitivity (Brosch and Schreiner, 2000; Nikolić et al., 2009). These studies suggest that sequence learning is an important problem that is solved by many cortical regions. "
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    • "Bartlett & Wang, 2005; Brosch & Scheich, 2008; Sadagopan & Wang, 2009). With both fast-and slowly-decaying synaptic adaptation , 16% of columns in the model showed facilitation – a lower proportion than the 40–60% values found in single-unit measurements in primates (Brosch & Schreiner, 2000; Bartlett & Wang, 2005; Brosch & Scheich, 2008). Irrespective of the time constant of synaptic adaptation, the magnitude of facilitation peaked in the lower range (110–140%), resembling the results from primate studies . "
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    • "Brosch et al. (1999) observed maximal enhancement of multi-unit responses in A1 of anesthetized macaque monkeys when a pair of tones were delivered with a stimulus-onset-asynchrony of 120 ms and a frequency separation of about one octave. A similar observation was made in A1 of anesthetized cats where the maximally enhanced responses occurred when the first tone was above one octave below or above the subsequently delivered second tone (Brosch and Schreiner, 2000). Brosch et al. (2013) reported that, in the caudomedial field of anesthetized macaque monkey auditory cortex, the likelihood of synchronization between spontaneous firings of a pair of simultaneously recorded multi-unit clusters was highest when the best frequencies of the two clusters were about an octave apart. "
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