The Role Of The Posterior Complex Of The Thalamus In Balance Control In Mice

GoalBalance control and posture maintaining are extremely important for efficient and stable locomotion.Feedforward and feedback regulation in the nervous system are involved in multiple stages of balance control,including sensory input,central integration,and motor command output.Among the numerous thalamic nuclei,the posterior complex of the thalamus(Po)receives projections from multiple brain regions,including the vestibular nucleus complex(VNC),zona incerta(ZI),and thalamic reticular nucleus(TRN).Previous results suggest that Po may be involved in the regulation of spatial position sensation,pain perception,and proprioception.Although Po may be engaged in the regulation of balance related sensory information,but there are few reports on the effects of Po on motor balance control.This study aims to explore the functional impact of Po on balance control and how the Po neurons behave during the motor balance.MethodsFirst,we injected AAV-CAG-TeNT-2A-EYFP in the Po brain region to turn off the output of Po neurons,and explore the effects of silencing Po on anxiety,locomotor activity,balance control,gait,and spatial location cognition and memory in mice using five behavioral paradigms: the open-field test,elevated plus maze test,balance beam test,gait test and novel object place recognition test.Then we used multichannel in vivo recordings to record the firing activities of neurons in Po during balance beam behavior in mice.Results(1)In the open field test,silencing the Po significantly decreased locomotor activity,whereas it had no impact on anxiety levels;(2)In the balance beam test,silencing the Po significantly increased the time to start and time taken to walk through the beam,and significantly increased the frequency of hind-feet slip;(3)In the gait test,silencing the Po significantly increased the hind-width and the overlap between fore and hind feet of mice,and significantly decreased the fore and hind length;(4)In the novel object place recognition test,silencing the Po had no significant effect on basal preference or test phase preference in mice.(5)The firing of Po neurons changed after the initiation of locomotion on the balance beam,with 65% of neurons showing specific or nonspecific responses to phases of movement,immobility.ConclusionSilencing Po significantly decreased locomotor activity,balance and motor coordination,and had no significant effect on anxiety levels and spatial location cognition and memory in mice.Po neurons are involved in the regulation of motor balance behavior.