Glennon 2022 - Cochear Implant Performance.

 

The paper discussed in my Multisensory Integration seminar class this week. 

Locus coeruleus activity improves cochlear implant performance  Glennon et al, 2022 

 

Takeaways

Key takeaway is that there is a lot of variability in CI outcomes (the time taken for hearing to be restored and perceptual accuracy after long-term CI use) with the researchers thinking this could be due to differences in neuroplasticity. 

Neuroimaging studies found that target tones selectively activated LC on correct trials after learning, suggesting a potential link between this area and CI performance. So a potent factor enabling plasticity was the neuromodulator noradrenaline from LC.

• This  study used optogenetics to study how LC neuron activity affects CI performance. Rats were trained on a reward-based auditory task and showed considerable individual differences of learning rates and maximum performance.
• LC stimulation predicted when CI subjects began responding to sounds and longer-term perceptual accuracy. Essentially, stimulating LC improved auditory responses and increased spiking output from cortical neurons when compared with control animals without LC stimulation. 

In short, there was faster learning and higher long-term accuracy when you stimulated the LC. 

Additionally, behavioral outcomes were found to be correlated with variability of foil channel responses, meaning different foils had similar evoked responses and thus shared a common behavioral meaning.

The implications from this paper are.

• Cortical responses to CI stimulation can be shaped by mechanisms of neuromodulator-enabled plasticity.
• Different stimuli associated with CI will evoke distinct neural responses in the auditory cortex, allowing for better classification and behavioral regulation of input signals.

Terms explained

• LC or Locus coeruleus is a part of the brainstem which plays an important role in regulating attention, arousal and other cognitive functions.
• Optogenetics. A technique that uses light-sensitive proteins to control neuronal activity with precise timing and spatial resolution.
• CI or Cochear Implant: neuroprosthetic devices that can provide hearing to deaf people
• Neuromodulation is the process of altering the activity of neurons in the brain by using electrical or chemical stimulation.
• Plasticity is the ability of the brain to change and adapt in response to experience.