02091nas a2200253   4500008004100000022001400041245004000055210003800095260001200133300001400145490000800159520142300167653002101590653002101611653002501632653001701657653001101674653001601685100002301701700002301724700002101747700002101768856004801789       2006                        eng d  a0014-481900aDiurnal H-reflex variation in mice.0 aDiurnal Hreflex variation in mice  c01/2006  a517–5280 v1683 aMice exhibit diurnal variation in complex motor behaviors, but little is known about diurnal variation in simple spinally mediated functions. This study describes diurnal variation in the H-reflex (HR), a wholly spinal and largely monosynaptic reflex. Six mice were implanted with tibial nerve cuff electrodes and electrodes in the soleus and gastrocnemius muscles, for recording of ongoing and nerve-evoked electromyographic activity (EMG). Stimulation and recording were under computer control 24 h/day. During a 10-day recording period, HR amplitude varied throughout the day, usually being larger in the dark than in the light. This diurnal HR variation could not be attributed solely to differences in the net ongoing level of descending and segmental excitation to the spinal cord or stimulus intensity. HRs were larger in the dark than in the light even after restricting the evoked responses to subsets of trials having similar ongoing EMG and M-responses. The diurnal variation in the HR was out of phase with that reported previously for rats, but was in phase with that observed in monkeys. These data, supported by those in other species, suggest that the supraspinal control of the excitability of the HR pathway varies throughout the day in a species-specific pattern. This variation should be taken into account in experimental and clinical studies of spinal reflexes recorded at different times of day.10acircadian rhythm10aElectromyography10aimplanted electrodes10aMonosynaptic10aReflex10aSpinal Cord1 aCarp, Jonathan, S.1 aTennissen, Ann, M.1 aChen, Xiang Yang1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/1615178101213nas a2200313   4500008004100000022001400041245005000055210004500105300001400150490000700164520043400171653001300605653001000618653001700628653002100645653001300666653001100679653001500690653001100705653001200716653001100728653001600739653001600755653002200771653001500793100002100808700002300829856004700852       1993                        eng d  a0065-140000aThe volitional nature of the simplest reflex.0 avolitional nature of the simplest reflex  a103–1110 v533 aRecent studies suggest that none of the behaviors of the vertebrate CNS are fixed responses incapable of change. Even the simplest reflex of all, the two-neuron, monosynaptic spinal stretch reflex (SSR), undergoes adaptive change under appropriate circumstances. Operantly conditioned SSR change occurs gradually over days and weeks and is associated with a complex pattern of CNS plasticity at both spinal and supraspinal sites.10abehavior10aBrain10aconditioning10ahuman physiology10aLearning10aMemory10amotoneuron10anature10aprimate10aReflex10aSpinal Cord10aspinal site10asupra spinal site10avertebrate1 aWolpaw, Jonathan1 aCarp, Jonathan, S.  uhttp://www.ncbi.nlm.nih.gov/pubmed/831723801279nas a2200169   4500008004100000022001400041245006200055210005700117260001200174300001400186490000800200520080000208653001101008100002301019700002101042856004601063       1979                        eng d  a0003-978000aThe effects of phenytoin on motor function in awake cats.0 aeffects of phenytoin on motor function in awake cats  c01/1979  a139–1480 v2373 aAdult cats were monitored for their performance of a variety of motor functions before and after acute administration of phenytoin (5, 10 or 20 mg/kg) in a schedule in which each animal received all drug doses. The only significant loss in motor function was balance and coordination. Half the animals could not balance or walk along a narrow-edged beam after 20 mg/kg of phenytoin although their performance was not impaired at lower drug doses or on wider surfaces. There were no effects of phenytoin on the righting reflex, flexor reflex, muscle strength, the hopping response, the blind placing response or visually aided placing. The data suggest that phenytoin has a selective effect on higher order neuronal systems involved with balance and locomotion rather than simple reflex pathways.10aReflex1 aCarp, Jonathan, S.1 aAnderson, R., J.  uhttp://www.ncbi.nlm.nih.gov/pubmed/485678