Development of a new tissue-friendly head implant for use in awake, behaving monkey studies

Project background

The understanding of both normal and disordered brain function relies on recording electrical signals generated by single neurons. These recordings are made in awake, behaving experimental animals performing movements similar to the human movements of interest. For example, the understanding of neural control of skilled hand movements and how these are disrupted by stroke or spinal injury is often studied in non-human primates. Stable recordings of individual cells require head restraint during the period of recording. Conventionally, this is achieved by surgically implanting an inert metal restraint device onto the animal’s skull.

Why we funded it

This Project Grant aims to develop a refined custom-fitted head-holding device for macaque monkeys using a non-invasive MRI-based approach.

The conventional restraint devices suffer persistent issues with infection and instability. The metal device is not tissue friendly and infected tissue can lead to tissue necrosis, requiring long periods of antibiotic treatment or euthanasia of the animal. Instability of the device impacts on data quality and can require further surgical intervention to stabilise the device or replace the device entirely.

Research methods

The restraint device to be developed in this project will be made from a bone-friendly synthetic that promotes natural bonding with bone regrowing from beneath the implant. This material is already used in human applications such as eye orbital reconstruction and is currently in development for the construction of artificial bone needed in brain surgery. Characteristics of the novel device will be evaluated throughout the study to compare against the conventional metal device ensuring its suitability and efficacy as well as comparing infection levels. The synthetic material is also compatible with magnetic resonance, whereas the metal implant is not, allowing non-invasive imaging to be carried out improving the yield of behavioural and neurophysiological data from each monkey.      

Vigneswaran G et al. (2013). M1 Corticospinal Mirror Neurons and Their Role in Movement Suppression during Action Observation. Current biology 23(3):236-243. doi: 10.1016/j.cub.2012.12.006 

Vigneswaran G et al. (2011). Large Identified Pyramidal Cells in Macaque Motor and Premotor Cortex Exhibit “Thin Spikes”: Implications for Cell Type Classification The Journal of Neuroscience 31(40):14235-1424; doi: 10.1523/JNEUROSCI.3142-11.2011 

Krasov K et al. (2011). Ventral Premotor–Motor Cortex Interactions in the Macaque Monkey during Grasp: Response of Single Neurons to Intracortical Microstimulation The Journal of Neuroscience 31(24):8812-882. doi: 10.1523/JNEUROSCI.0525-11.2011

Kraskov A et al. (2009). Corticospinal Neurons in Macaque Ventral Premotor Cortex with Mirror Properties: A Potential Mechanism for Action Suppression? Neuron 64(6):922-930. doi: 10.1016/j.neuron.2009.12.010

• Resources: Chronic Implants Wiki