Exemple de méthodes d’enregistrements de neurones: implants d’électrodes permanents:

Figure 1. Recording with permanently implanted electrode arrays.
In the last few years, I have contributed to the implementation and use of microarrays in Dr Marc Schieber’s laboratory at the University of Rochester. We have implanted several animals, progressively increasing the number of implanted electrodes from 64 to 308. These arrays allow the simultaneous recording of multiple single-neurons and local field potentials in multiple cortical areas and can also be used for microstimulation. A) Floating electrode arrays (Microprobes, inc.) can have specified electrode lengths, which allows the targeting of cortex located deep in sulci. B) These arrays can be paired with one or more cannulae to allow drug delivery (arrowhead). C) Example of implantation surgery in one of my monkeys in Rochester during which we implanted M1, PMv and PMd.In the implantation surgery, ICMS mapping techniques will be used to identify the location of the hand representations and arrays will be place to maximize the recording of neurons in this representation.

 

 

Exemple de session d’enregistrement de neurones chez le singe éveillé

 

Figure 2. Simultaneous recording of multiple neurons.
Example of simultaneous recording done in our monkeys in Dr Marc Schieber’s laboratory in Rochester. In this example, we are recordings simultaneously with both a Plexon system recording from floating microarrays (top) and Cerebus system recording from a Utah array (bottom) while the monkey performs a task. A total of 224 channels are being recorded covering M1, PMd, PMv and the primary somatosensory cortex. While some online spike sorting is possible (top left and spikes traces of different colors), most of the sorting is done offline with software provided by the manufacturer. In the current proposal, we will use a data acquisition system that allows the simultaneous recording of up to 256 channels while also recording EMG and kinematics of the impaired arm.

Exemple d’analyse de neurones enregistrés dans le cortex prémoteur ventral (PMv) pendant des mouvements des bras

Figure 3. Examples of hand-related neurons in the ventral premotor cortex (PMv) during reaching and grasping movements of the right or left arm.
I recorded these neurons during my post-doctoral studies in Rochester. In this task, the monkeys had to combine head movements with reaching and grasping movements with either the right or the left arm. The legend below explains the meaning of the symbols shown for each trial. We show 6 seconds of acquired data for each trial which are all aligned at the moment when the hand reached the target. In all 3 examples, neurons were recorded in the right hemisphere PMv and had activity that was significantly modulated during movements of the arms.A) Neuron o0248 was significantly modulated during the reach of the left (contralateral) arm. Based on the laterality index (right) this neuron can be classified as ‘contralateral’.B) Neuron o0235 was significantly modulated during the grasp epoch and the burst was similar whether the monkey used its left or right hand. Based on the laterality index this neuron can classified as ‘complete bilateral’.C) We also found neurons like o0244. This neuron was significantly modulated during the grasp epoch, and was more active during grasp with the ipsilateral hand. Based on the laterality index this neuron could be classified as ‘partial bilateral’ with a preference for ipsilateral movements.