Delta waves on EEG are recorded in:September 2007
**Core Concept**
Delta waves on EEG are a type of brain wave pattern characterized by high amplitude and low frequency oscillations, typically in the range of 0.5-4 Hz. They are most commonly associated with deep sleep, unconsciousness, and in infants, normal brain development.
**Why the Correct Answer is Right**
Delta waves are generated by the synchronized firing of neurons in the brain, particularly in the cerebral cortex. This synchronized activity is thought to be mediated by the release of neurotransmitters such as GABA and acetylcholine, which modulate the activity of neurons. In infants, delta waves are a normal feature of brain development, reflecting the maturation of the brain's electrical activity. During deep sleep, delta waves are thought to play a role in the consolidation of memories and the restoration of the brain's energy resources.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because delta waves are not typically associated with wakefulness or alertness, although they can be seen in some cases of coma or brain injury.
**Option B:** This option is incorrect because alpha waves, not delta waves, are typically associated with relaxation and closed eyes.
**Option C:** This option is incorrect because beta waves, not delta waves, are typically associated with active thinking and problem-solving.
**Clinical Pearl / High-Yield Fact**
Delta waves are an important marker of deep sleep, and their presence can be used to diagnose disorders such as sleep apnea or narcolepsy.
**Correct Answer: D. Infants, during deep sleep.**