CHANGES INBREATHING,ELECTROCORTICALAND MUSCLE ACTIVITYINUNANAESTHETIZED FETALLAMBS WITH AGE

SUMMARY 1.Electrocortical andelectro-ocular activity, breathing movements andnuchal muscle activity wererecorded continuously intheunanaesthetized lambinUtero (95-135 days). 2.Electrocortical activity wasrecorded simultaneously fromvarious sites. The bi-parietal electrocorticogram gavetheclearest differentiation between high- and low-voltage activity. 3.Theonsetofcortical differentiation from110daysgestation wasattributed to thesuperimposition ofhigh-voltage electrocortical activity at3-10Hzonexisting low-voltage activity. 4.Threedistinct patterns intherelationships between electrocortical activity, ocular activity breathing movements andnuchal muscle activity wereobserved at 95-106, 107-114 and120-135 days. 5.Isocapnic hypoxia caused adiminution infetal breathing from95-135days gestation, quantitatively greater nearterm.After cortical differentiation, hypoxia caused theappearance ofhigh-voltage activity within 4min,iflow-voltage electrocortical activity waspresent initially. 6.Therelationship, changing withage,between electrocortical activity, breathing movements, ocular andnuchal muscle activity isdiscussed.