Limits...
Across-ear stimulus-specific adaptation in the auditory cortex.

Xu X, Yu X, He J, Nelken I - Front Neural Circuits (2014)

Bottom Line: The ability to detect unexpected or deviant events in natural scenes is critical for survival.In the auditory system, neurons from the midbrain to cortex adapt quickly to repeated stimuli but this adaptation does not fully generalize to other rare stimuli, a phenomenon called stimulus-specific adaptation (SSA).Most studies of SSA were conducted with pure tones of different frequencies, and it is by now well-established that SSA to tone frequency is strong and robust in auditory cortex.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biophysics, Chinese Academy of Sciences Beijing, China ; University of Chinese Academy of Sciences Beijing, China.

ABSTRACT
The ability to detect unexpected or deviant events in natural scenes is critical for survival. In the auditory system, neurons from the midbrain to cortex adapt quickly to repeated stimuli but this adaptation does not fully generalize to other rare stimuli, a phenomenon called stimulus-specific adaptation (SSA). Most studies of SSA were conducted with pure tones of different frequencies, and it is by now well-established that SSA to tone frequency is strong and robust in auditory cortex. Here we tested SSA in the auditory cortex to the ear of stimulation using broadband noise. We show that cortical neurons adapt specifically to the ear of stimulation, and that the contrast between the responses to stimulation of the same ear when rare and when common depends on the binaural interaction class of the neurons.

Show MeSH
Population responses of subgroups of EO neurons. (A) PSTH showing the mean responses of EO/I (top), EO/N (middle) and EO/F (bottom) neurons in the oddball paradigm when presented to the contralateral ear. (B) The scatter plots the SI of three kinds of EO neurons vs. BII (binaural interaction index). There are three dots of which x value equaling 0 because they did not respond at all when the stimuli were presented to binaural ears. (C) Average SI of the classes of EO neurons (mean ± s.e.m., 0.224 ± 0.043, p < 10−5; 0.097 ± 0.024, p < 10−3; 0.084 ± 0.079, p = 0.312 for EO/I, EO/N and EO/F respectively, t-test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4115630&req=5

Figure 4: Population responses of subgroups of EO neurons. (A) PSTH showing the mean responses of EO/I (top), EO/N (middle) and EO/F (bottom) neurons in the oddball paradigm when presented to the contralateral ear. (B) The scatter plots the SI of three kinds of EO neurons vs. BII (binaural interaction index). There are three dots of which x value equaling 0 because they did not respond at all when the stimuli were presented to binaural ears. (C) Average SI of the classes of EO neurons (mean ± s.e.m., 0.224 ± 0.043, p < 10−5; 0.097 ± 0.024, p < 10−3; 0.084 ± 0.079, p = 0.312 for EO/I, EO/N and EO/F respectively, t-test).

Mentions: To classify the responses recorded from each unit, a three-letter code used in previous studies was employed with the first two letters expressing contralateral and ipsilateral responses respectively and the third the binaural interaction (Goldberg and Brown, 1969; Reale and Kettner, 1986; Kelly and Judge, 1994; Irvine et al., 1996). Neurons were classified as EE, EO, OE and PB (predominantly binaural, neurons that did not respond to stimulation of either ear, or only very weakly, but responded strongly to binaural stimulation). E represents the presence of an excitatory response to the corresponding ear while O represents poor or no response. Similar to earlier studies (Zhang et al., 2004), a criterion level of a 20% change in response was used to define the type of binaural interaction though it seems arbitrary. For EE neurons, the binaural interaction was classified as inhibition (I) if the binaural response was less than 80% of the monaural response to the dominant ear. It was classified as occlusion (O) if the binaural response was between 80% of the sum of the two monaural responses and 80% of the monaural response to the dominant ear. A binaural response that was within 20% of the sum of the respective monaural responses was considered to be no significant binaural interaction (N). A binaural interaction that produced a response to a binaural stimulus that was >120% of the sum of the monaural responses was classified as facilitation (F). For EO or OE neurons, inhibition (I) was considered to be present when the binaural response was less than 80% of the response to monaural stimulation of the dominant ear. The dominant ear was either contralateral ear for EO neurons or ipsilateral ear for OE neurons. A binaural response within ±20% of the response of the dominant ear was considered as indicative of no interaction (N). A binaural response greater than 120% of the monaural response to the dominant ear was classified as facilitation (F). We defined the binaural interaction index (BII) as the ratio of the binaural response to the contralateral response of EO neurons. The subclasses as defined here were somewhat arbitrary since a 20% increase or decrease could be statistically significant or not, and since the degree of binaural effects varied continuously over a continuum (e.g., Figure 4). However, the classification is still useful since it allows comparison with previous studies, and since it correlated with other features of the neuronal responses studied here, notably the SI.


Across-ear stimulus-specific adaptation in the auditory cortex.

Xu X, Yu X, He J, Nelken I - Front Neural Circuits (2014)

Population responses of subgroups of EO neurons. (A) PSTH showing the mean responses of EO/I (top), EO/N (middle) and EO/F (bottom) neurons in the oddball paradigm when presented to the contralateral ear. (B) The scatter plots the SI of three kinds of EO neurons vs. BII (binaural interaction index). There are three dots of which x value equaling 0 because they did not respond at all when the stimuli were presented to binaural ears. (C) Average SI of the classes of EO neurons (mean ± s.e.m., 0.224 ± 0.043, p < 10−5; 0.097 ± 0.024, p < 10−3; 0.084 ± 0.079, p = 0.312 for EO/I, EO/N and EO/F respectively, t-test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4115630&req=5

Figure 4: Population responses of subgroups of EO neurons. (A) PSTH showing the mean responses of EO/I (top), EO/N (middle) and EO/F (bottom) neurons in the oddball paradigm when presented to the contralateral ear. (B) The scatter plots the SI of three kinds of EO neurons vs. BII (binaural interaction index). There are three dots of which x value equaling 0 because they did not respond at all when the stimuli were presented to binaural ears. (C) Average SI of the classes of EO neurons (mean ± s.e.m., 0.224 ± 0.043, p < 10−5; 0.097 ± 0.024, p < 10−3; 0.084 ± 0.079, p = 0.312 for EO/I, EO/N and EO/F respectively, t-test).
Mentions: To classify the responses recorded from each unit, a three-letter code used in previous studies was employed with the first two letters expressing contralateral and ipsilateral responses respectively and the third the binaural interaction (Goldberg and Brown, 1969; Reale and Kettner, 1986; Kelly and Judge, 1994; Irvine et al., 1996). Neurons were classified as EE, EO, OE and PB (predominantly binaural, neurons that did not respond to stimulation of either ear, or only very weakly, but responded strongly to binaural stimulation). E represents the presence of an excitatory response to the corresponding ear while O represents poor or no response. Similar to earlier studies (Zhang et al., 2004), a criterion level of a 20% change in response was used to define the type of binaural interaction though it seems arbitrary. For EE neurons, the binaural interaction was classified as inhibition (I) if the binaural response was less than 80% of the monaural response to the dominant ear. It was classified as occlusion (O) if the binaural response was between 80% of the sum of the two monaural responses and 80% of the monaural response to the dominant ear. A binaural response that was within 20% of the sum of the respective monaural responses was considered to be no significant binaural interaction (N). A binaural interaction that produced a response to a binaural stimulus that was >120% of the sum of the monaural responses was classified as facilitation (F). For EO or OE neurons, inhibition (I) was considered to be present when the binaural response was less than 80% of the response to monaural stimulation of the dominant ear. The dominant ear was either contralateral ear for EO neurons or ipsilateral ear for OE neurons. A binaural response within ±20% of the response of the dominant ear was considered as indicative of no interaction (N). A binaural response greater than 120% of the monaural response to the dominant ear was classified as facilitation (F). We defined the binaural interaction index (BII) as the ratio of the binaural response to the contralateral response of EO neurons. The subclasses as defined here were somewhat arbitrary since a 20% increase or decrease could be statistically significant or not, and since the degree of binaural effects varied continuously over a continuum (e.g., Figure 4). However, the classification is still useful since it allows comparison with previous studies, and since it correlated with other features of the neuronal responses studied here, notably the SI.

Bottom Line: The ability to detect unexpected or deviant events in natural scenes is critical for survival.In the auditory system, neurons from the midbrain to cortex adapt quickly to repeated stimuli but this adaptation does not fully generalize to other rare stimuli, a phenomenon called stimulus-specific adaptation (SSA).Most studies of SSA were conducted with pure tones of different frequencies, and it is by now well-established that SSA to tone frequency is strong and robust in auditory cortex.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biophysics, Chinese Academy of Sciences Beijing, China ; University of Chinese Academy of Sciences Beijing, China.

ABSTRACT
The ability to detect unexpected or deviant events in natural scenes is critical for survival. In the auditory system, neurons from the midbrain to cortex adapt quickly to repeated stimuli but this adaptation does not fully generalize to other rare stimuli, a phenomenon called stimulus-specific adaptation (SSA). Most studies of SSA were conducted with pure tones of different frequencies, and it is by now well-established that SSA to tone frequency is strong and robust in auditory cortex. Here we tested SSA in the auditory cortex to the ear of stimulation using broadband noise. We show that cortical neurons adapt specifically to the ear of stimulation, and that the contrast between the responses to stimulation of the same ear when rare and when common depends on the binaural interaction class of the neurons.

Show MeSH