Task Engagement Selectively Modulates Neural Correlations in Primary Auditory Cortex

Abstract

Noise correlations (r noise ) between neurons can affect a neural population's discrimination capacity, even without changes in mean firing rates of neurons. r noise , the degree to which the response variability of a pair of neurons is correlated, has been shown to change with attention with most reports showing a reduction in r noise . However, the effect of reducing r noise on sensory discrimination depends on many factors, including the tuning similarity, or tuning correlation (r tuning ), between the pair. Theoretically, reducing r noise should enhance sensory discrimination when the pair exhibits similar tuning, but should impair discrimination when tuning is dissimilar. We recorded from pairs of neurons in primary auditory cortex (A1) under two conditions: while rhesus macaque monkeys (Macaca mulatta) actively performed a threshold amplitude modulation (AM) detection task and while they sat passively awake. We report that, for pairs with similar AM tuning, average r noise in A1 decreases when the animal performs the AM detection task compared with when sitting passively. For pairs with dissimilar tuning, the average r noise did not significantly change between conditions. This suggests that attention-related modulation can target selective subcircuits to decorrelate noise. These results demonstrate that engagement in an auditory task enhances population coding in primary auditory cortex by selectively reducing deleterious r noise and leaving beneficial r noise intact.

Intracranial Electrophysiology of Auditory Selective Attention Associated with Speech Classification Tasks

“…In contrast to current findings and previous human intracranial studies (Steinschneider et al, 2014; Nourski et al, 2015), animal studies show considerable attentional and task-related effects at the level of primary auditory cortex (e.g., Fritz et al, 2003; Brosch et al, 2005; Atiani et al, 2009; Downer et al, 2015; but see Atiani et al, 2014). Two possible explanations may account for this discrepancy.…”

Contextual modulation of sound processing in the auditory cortex

“…While changes in rate and phase-locking are both correlated with behavioral performance, changes in rate are more affected by task engagement and are more correlated with behavior, implicating a multiplexed temporal- and rate-code that is dominated by firing rate changes during behavior (Figure 4) [74,75]. On a population level, neurons with similar AM tuning decrease their noise correlations during active engagement, while noise correlations in neurons with dissimilar AM tuning are unaffected, suggesting that AC selectively modulates population variability to maximize sensory discrimination [76]. Taken together, these results demonstrate that auditory cortex is highly plastic, rapidly adjusting its single-unit and population response properties to optimally encode stimulus features that are relevant to the current behavioral task.…”

Feedforward and feedback sources of choice probability in neural population responses

“…46–48 task engagement 49 , task difficulty 50 , learning 51 , or anesthesia 52 . Most of these studies observed uniform changes in noise correlation, not changes in the structure of the noise correlations, and would therefore not influence CPs.…”