During the first few months of life, the human brain develops at a considerable rate. Mesa Community College states that at birth, the brain is 30 percent of its adult size; by the time the child is a year old, her brain is 55 percent of its adult size. Between birth and the child's first year of life, the myelin sheath is deposited, which protects the axons of the neuron and insulates the signal being sent between the neurons. Mesa Community College notes that when the child is sitting, standing and walking, the neural pathways are functionally complete.

North Dakota State University notes that emotional and social development occur between birth and age 12, though emotional attachment develops between birth and 18 months. Research published in Neuron found that infants start detecting the emotional tone in spoken language as early as 7 months old.

Using a near-infrared spectroscopy, the researchers looked at regions of the temporal lobe linked to the human voice, such as the superior temporal sulcus. The publisher, Cell Press, noted that 7-month-old children “showed adult-like increased responses in the temporal cortex, in response to the human voice, when compared to nonvocal sounds.”

Researchers found that when the children listened to speech that was spoken in an emotional prosody, either angry or happy, the right temporal cortex increases in activity. Prosody reflects feelings of the person speaking, which the researchers describe as the “music of speech.” For example, the child will pick up more on someone who is speaking with a sad tone rather than someone who is speaking with no emotional tone.

The discovery that children process emotional tone in speech the same as adults may provide insight into disorders like autism. The National Institutes of Health (NIH) states that a patient with autism has problems responding to smiles and shows a lack of empathy. The Mayo Clinic adds that the patient is also unaware of other people's feelings. An autistic patient may have deficits in those areas of the brain, which can result in the emotional disconnect.

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Elizabeth Stannard Gromisch received her bachelor’s of science degree in neuroscience from Trinity College in Hartford, CT in May 2009. She is the Hartford Women's Health Examiner and she writes about abuse on Suite 101.