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Theta Waves

Normal Occurrence of Theta Waves

  • Theta waves oscillate about 3.5 – 7.5 times per second (Hz).
  • Some consider Theta to be from 4 – 8 Hz.
  • Theta is normal in small very amounts in the healthy waking adult EEG.
  • Theta in the adult waking EEG should be symmetrically distributed.
  • Theta is more prominent and considered normal in the raw EEG’s of children & adolescents unless there is clear indication of pathology.
  • Theta at the scalp surface in the adult EEG is normal as part of the early stages of drowsiness.
  • Theta may occur in some individuals who are day dreaming.
  • Some individuals produce a frontal-midline Theta (FZ) under task conditions that can be recorded at the scalp and is dependent on task difficulty and reflects transfer of information to long-term memory / memory functions

Abnormal Occurrence of Theta Waves

  • Excessive Theta activity in the waking raw EEG of adults is considered abnormal. It can represent reduced metabolism cortical grey matter (too little oxygen uptake).
  • Theta that is asymmetrically distributed in the waking adult EEG is considered abnormal (more on one side than the other)
  • Spike and slow wave complexes that occur in seizure disorder often occur in the Theta frequency range.
  • Excessive Theta on quantitative analysis is often seen in conditions such as…
    • ADHD
    • Learning disabilities
    • Head injuries or brain lesions
    • Certain neurological disorders

Physiological Origin of Theta Wave Rhythms

  • Cortical Theta generation in humans is projected to the cortex via Thalamo-cortical projections and is influenced by GABAergic / Cholinergic inhibitory & excitatory inputs from the Reticular Activating System.
  • Cortical Theta is essentially a slowing of the Alpha rhythm but may also be influenced by limbically generated (septo-hippocampul) Theta as described below.
  • Sub-cortical Theta Rhythms are prominent in the Hippocampus & Limbic system and result from alternating inhibition / disinhibition between the septal nuclei & hippocampal nuclei.
  • Limbic Theta oscillations are caused by alternating inhibition / disinhibition of GABAergic & Cholinergic neurons.
  • The hippocampus is part of the “Papez Circle” including the Hippocampus (HIP), Entorhinal Cortex in Temporal Lobes, Sensory areas of the Temporals & Parietals, the Mammillary Bodies of the Hypothalamus, and the Thalamus that are involved in memory consolidation.

Role of Theta Waves in Having a Healthy Brain

  • Hippocampal & Limbic Theta are highly involved in the encoding of meaningful events into long-term memory.
  • Cortical Theta likely represents a “binding rhythm” that ties functionally related neural networks together in time for coordinated processing of memory storage functions.
  • Inducing a Theta state via hypnosis or neurofeedback may aid in anxiety reduction and the processing of traumatic memories such as may occur in PTSD

Images of Theta Waves

Single channel;

Theta Waves in Raw EEG

19 Channel: Linked Ear Montage;

28 year old male with ADHD, Inattentive Type. Examples Highlighted in Red

19 Channel Theta Waves: Linked Ear Montage.

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Our Director

Robert Gurnee, MSW, DCSW, Director

Past president of the International Society of Neurofeedback & Research

Past president of the Neurofeedback Division of the Association of Applied Psychophysiology & Biofeedback

Our Location

Scottsdale Neurofeedback Institute
8114 E. Cactus Road - Suite 200
Scottsdale, Arizona, 85260

Opening Hours:
Monday - Friday 8.30am to 6pm

Phone: (480) 625-4123
Fax: (480) 424-7800