Hemodynamic Responses Evoked by Neuronal Stimulation via Channelrhodopsin-2 Can Be Independent of Intracortical Glutamatergic Synaptic Transmission

Maintenance of neuronal function depends on the delivery of oxygen and glucose through changes in blood flow that are linked to the level of ongoing neuronal and glial activity, yet the underlying mechanisms remain unclear. Using transgenic mice expressing the light-activated cation channel channelrhodopsin-2 in deep layer pyramidal neurons, we report that changes in intrinsic optical signals and blood flow can be evoked by activation of a subset of channelrhodopsin-2-expressing neurons in the sensorimotor cortex. We have combined imaging and pharmacology to examine the importance of glutamatergic synaptic transmission in this form of neurovascular coupling. Blockade of ionotropic glutamate receptors with the antagonists CNQX and MK801 significantly reduced forepaw-evoked hemodynamic responses, yet resulted in no significant reduction of channelrhodopsin-evoked hemodynamic responses, suggesting that stimulus-dependent coupling of neuronal activity to blood flow can be independent of local excitatory synaptic transmission. Together, these results indicate that channelrhodopsin-2 activation of sensorimotor excitatory neurons produces changes in intrinsic optical signals and blood flow that can occur under conditions where synaptic activation of neurons or other cells through ionotropic glutamate receptors would be blocked

The occurrence of Mycoplasma phocicerebrale, Mycoplasma phocidae, and Mycoplasma phocirhinis in grey and common seals (Halichoerus grypus and Phoca vitulina) in the United Kingdom

Following the isolation of Mycoplasma phocicerebrale from the flipper wound of a grey seal (Halichoerus grypus) in Cornwall, UK, surveillance for Mycoplasma species was extended to include other seals rescued or found dead around the UK. Mycoplasma phocicerebrale was frequently detected from the teeth of seals and from infected wounds and respiratory tracts. Mycoplasma phocirhinis, Mycoplasma phocidae, and some unidentified Mycoplasma species were also detected. Mycoplasma phocicerebrale and M. phocidae were the only bacteria consistently identified from the wound infections, but their role in respiratory and other diseases remains unknown, as other bacteria were also isolated from respiratory sites