88
Chapter 1: Neural Sciences
hyperactivity disorder (ADHD), and learning disability subpopulations.
QEEG findings in ADHD show that increased theta abnormality fron-
tally may be a strong predictor of response to methylphenidate and other
psychostimulants and that favorable clinical responses may be associated
with a normalization of the EEG abnormality.
Cerebral Evoked Potentials
Cerebral EPs are a series of surface (scalp) recordable waves
that result from brain visual, auditory, somatosensory, and
cognitive stimulation. They have been shown to be abnormal
in many psychiatric conditions, including schizophrenia and
Alzheimer’s disease, thus creating difficulty in using cerebral
EPs for differential diagnosis purposes.
R
eferences
Alhaj H, Wisniewski G, McAllister-Williams RH. The use of the EEG in measur-
ing therapeutic drug action: Focus on depression and antidepressants.
J Psycho-
pharmacol.
2011;25:1175.
André VM, Cepeda C, Fisher YE, Huynh MY, Bardakjian N, Singh S, Yang XW,
Levine MS. Differential electrophysiological changes in striatal output neurons
in Huntington’s disease.
J Neurosci.
2011;31:1170.
Boutros NN, Arfken CL. A four-step approach to developing diagnostic testing in
psychiatry.
Clin EEG Neurosci.
2007;38:62.
Boutros NN, Galderisi S, Pogarell O, Riggio S, eds.
Standard Electroencephalography
in Clinical Psychiatry:A Practical Handbook.
Hoboken, NJ:Wiley-Blackwell; 2011.
Boutros NN, Iacono WG, Galderisi S. Applied electrophysiology. In: Sadock BJ,
Sadock VA, Ruiz P, eds.
Kaplan & Sadock’s Comprehensive Textbook of Psy-
chiatry.
9
th
ed. Philadelphia: Lippincott Williams & Wilkins; 2009:211.
Gosselin N, Bottari C, Chen JK, Petrides M, Tinawi S, de Guise E, Ptito A. Elec-
trophysiology and functional MRI in post-acute mild traumatic brain injury.
J Neurotrauma.
2011;28:329.
HoranWP, Wynn JK, KringAM, Simons RF, Green MF. Electrophysiological corre-
lates of emotional responding in schizophrenia.
J Abnorm Psychol.
2010;119:18.
Hunter AM, Cook IA, Leuchter AF. The promise of the quantitative electroenceph-
alogram as a predictor of antidepressant treatment outcomes in major depres-
sive disorder.
Psychiatr Clin North Am.
2007;30:105.
Jarahi M, Sheibani V, Safakhah HA, Torkmandi H, Rashidy-Pour A. Effects of pro-
gesterone on neuropathic pain responses in an experimental animal model for
peripheral neuropathy in the rat: A behavioral and electrophysiological study.
Neuroscience
. 2014;256:403–411.
Winterer G, McCarley RW. Electrophysiology of schizophrenia. In: Weinberger
DR, Harrison PJ.
Schizophrenia.
3
rd
ed. Hoboken, NJ: Blackwell Publishing
Ltd; 2011:311.
▲▲
1.9 Chronobiology
Chronobiology
is the study of biological time. The rotation of the
Earth about its axis imposes a 24-hour cyclicity on the biosphere.
Although it is widely accepted that organisms have evolved to
occupy geographical niches that can be defined by the three spa-
tial dimensions, it is less appreciated that organisms have also
evolved to occupy temporal niches that are defined by the fourth
dimension—time. Much like light represents a small portion of
the electromagnetic spectrum, the 24-hour periodicity represents
a small time domain within the spectrum of temporal biology.
A broad range of frequencies exist throughout biology, ranging
from millisecond oscillations in ocular field potentials to the
17-year cycle of emergence seen in the periodic cicada (
Magici-
cada
spp.). Although these different periodicities all fall within
the realm of chronobiology,
circadian
(Latin:
circa,
about;
dies,
day) rhythms that have a period of about one day are among the
most extensively studied and best understood biological rhythms.
A defining feature of circadian rhythms is that they persist
in the absence of time cues and are not simply driven by the
24-hour environmental cycle. Experimental animals housed
for several months under constant darkness, temperature, and
humidity continue to exhibit robust circadian rhythms. Mainte-
nance of rhythmicity in a “timeless” environment points to the
existence of an internal biological timing system that is respon-
sible for generating these endogenous rhythms.
The site of the primary circadian oscillator in mammals,
including humans, is the suprachiasmatic nucleus (SCN), located
in the anterior hypothalamus. The mean circadian period gener-
ated by the human SCN is approximately 24.18 hours. Like a
watch that ticks 10 minutes and 48 seconds too slowly per day, an
individual with such a period gradually comes out of synchrony
with the astronomical day. In slightly more than 3 months, a
normally diurnal human would be in antiphase to the day–night
cycle and thus would become transiently nocturnal. Therefore,
a circadian clock must be reset on a regular basis to be effective
at maintaining the proper phase relationships of behavioral and
physiological processes within the context of the 24-hour day.
Although factors such as temperature and humidity exhibit
daily fluctuations, the environmental parameter that most reli-
ably corresponds to the period of Earth’s rotation around its axis
is the change in illuminance associated with the day–night cycle.
Accordingly, organisms have evolved to use this daily change in
light levels as a time cue or
zeitgeber
(German:
zeit,
time;
geber,
giver) to reset the endogenous circadian clock. Regulation of the
circadian pacemaker through the detection of changes in illumi-
nance requires a photoreceptive apparatus that communicates
with the central oscillator. This apparatus is known to reside in
the eyes, because surgical removal of the eyes renders an animal
incapable of resetting its clock in response to light.
The circadian clock drives many rhythms, including rhythms
in behavior, core body temperature, sleep, feeding, drinking,
and hormonal levels. One such circadian-regulated hormone is
the indoleamine, melatonin. Melatonin synthesis is controlled
through a multisynaptic pathway from the SCN to the pineal
gland. Serum levels of melatonin become elevated at night and
return to baseline during the day. The nocturnal rise in melato-
nin is a convenient marker of circadian phase. Exposure to light
elicits two distinct effects on the daily melatonin profile. First,
Table 1.8-5
Electroencephalography (EEG) Alterations
Associated with Psychiatric Disorders
Panic disorder
Paroxysmal EEG changes consistent
with partial seizure activity during
attack in one third of patients; focal
slowing in about 25% of patients
Catatonia
Usually normal, but EEG indicated in
new patient presenting with catato-
nia to rule out other causes
Attention-deficit/
hyperactivity disor-
der (ADHD)
High prevalence (up to 60%) of EEG
abnormalities versus normal con-
trols; spike or spike-wave discharges
Antisocial personality
disorder
Increased incidence of EEG abnormali-
ties in those with aggressive behavior
Borderline personality
disorder
Positive spikes: 14 and 6 per second
seen in 25% of patients
Chronic alcoholism Prominent slowing and periodic later-
alized paroxysmal discharges
Alcohol withdrawal
May be normal in patients who are
not delirious; excessive fast activity
in patients with delirium
Dementia
Rarely normal in advanced dementia;
may be helpful in differentiating
pseudodementia from dementia
