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The smile in anencephalic infants
1Department of Neurosurgery, University Hospital, Leiden, The Netherlands.
Insights
Newborns with mero-anencephaly, a severe birth defect, exhibited smiling responses to stimuli. This suggests the neural smile mechanisms may be located in the brainstem's pontine tegmentum.
Area of Science:
- Neuroscience
- Developmental Biology
- Pediatrics
Background:
- Mero-anencephaly is a severe congenital condition characterized by the absence of a large part of the brain and skull.
- Survival beyond the neonatal period is rare but allows for observation of neurological responses.
Observation:
- Twelve newborns with mero-anencephaly surviving over 24 hours were studied.
- Tactile or electrical stimulation of specific facial areas in four infants elicited a distinct facial expression.
- This expression was consistently perceived as smiling or laughing by observers.
Findings:
- A high percentage (78%) of observers identified the facial expression as a smile, laugh, or grin.
- Neuroanatomical examination revealed a largely intact pontine tegmentum in these infants.
- The pontine tegmentum is the most rostral identifiable structure within the brainstem.
Implications:
- The study hypothesizes that the neural mechanisms controlling smiling are localized within the pontine tegmentum.
- This finding offers insights into the localization of complex facial expressions in the developing brain.
- Further research can explore the role of the brainstem in emotional expression in infants with congenital anomalies.
Abstract:
During the period 1947-1959 twelve new-born mero-anencephalics were observed, who survived for more than 1 day after birth. Two even lived for 20 and 237 days, respectively. In 4 of the 12 children studied touching or slight pressure, and also faradic stimulation of various spots of the cerebro-vascular area were invariably followed by a facial expression which was very similar to smiling. Movies of it were shown to groups of impartial observers. In 78% the facial expression was judged to be a smile, a laugh or a grin. The neuroanatomical finding of a largely intact pontine tegmentum as being the most rostrally situated identifiable structure of the brainstem, has led to the hypothesis that the neural mechanisms underlying the smile are localized in the pontine tegmentum.