The Fitzhugh-Nagumo Model Note that the excitatory action potential (red) spikes, then subsides quickly at the onset of the inhibitory current (blue). As inhibition reaches its peak, the action potential is extinguished. The inhibitory action persists long after the cessation of the action potential. More...

Excitation and Inhibition

Sherrington, C. S.
Inhibition as a Coordinative Factor.*
Nobel Lecture, 12 December, 1932.

Sherrington CS
Some Comparisons Between Reflex Inhibition and Reflex Excitation
1908;1;67-78 Q J Exp Physiol

Peter Jonas and Gyorgy Buzsaki
Neural inhibition
Scholarpedia, 2007, 2(9):3286.

• "...inhibitory interneurons do much more than just provide stop signals for excitation. Proper dynamics in neuronal networks can only be maintained if the excitatory forces are counteracted by effective inhibitory forces. With only excitatory cells, it would be difficult to create form or order or secure some autonomy for transiently active groups, the hypothetical "cell assemblies", because in interconnected networks, excitation begets more excitation. Interneurons, by way of their inhibitory actions, provide the necessary autonomy and independence to neighboring principal cells."

Feldenkrais, M.
Comments on Pavlov's "internal inhibition"
Body and Mature Behavior. p. 46.

Ivan P. Pavlov. Translated by G. V. Anrep.
Conditioned reflexes: An investigation of the physiological activity of the cerebral cortex
Lecture XV. Internal inhibition and sleep as one and the same process with regard to their intimate mechanism*

Werhahn KJ, Behrang-Nia M, Bott MC, Klimpe S.
Does the recruitment of excitation and inhibition in the motor cortex differ?
J Clin Neurophysiol. 2007 Oct;24(5):419-23.
PMID: 17912067

• The level of excitability within the motor cortex can be described as a balance between excitation and inhibition, but it is unknown how well both processes correlate.... The findings suggest that recruitment of inhibition and excitation within the sensorimotor cortex correlate. However, inhibitory effects are recruited at lower intensities and saturate earlier than excitation.

Liepert J, Dettmers C, Terborg C, Weiller C.
Inhibition of ipsilateral motor cortex during phasic generation of low force.
Clin Neurophysiol. 2001 Jan;112(1):114-21.

• Phasic pinch grips with low force (1% of maximum voluntary contraction) inhibit the motor cortex responsible for the contralateral homologous hand muscle. This effect, which is probably mediated transcallosally, might act at the level of the motor cortex.

Weiss AC, Weiller C, Liepert J.
Pre-movement motor excitability is reduced ipsilateral to low force pinch grips.
J Neural Transm. 2003 Feb;110(2):201-8.

• "We conclude that the motor cortex ipsilateral to low force movements is inhibited prior to and during movement."

Zoghi M, Pearce SL, Nordstrom MA.
Differential modulation of intracortical inhibition in human motor cortex during selective activation of an intrinsic hand muscle.
J Physiol. 2003 Aug 1;550(Pt 3):933-46. Epub 2003 Jun 13.

• The pattern of differential modulation of ICI effectiveness with voluntary activation suggests that the ICI circuits assist the corticospinal system in producing fractionated activity of intrinsic hand muscles.

Stinear CM, Byblow WD.
Role of intracortical inhibition in selective hand muscle activation.
J Neurophysiol. 2003 Apr;89(4):2014-20. Epub 2003 Jan 2

• These findings suggest that an increase in ICI and decrease in corticospinal excitability can prevent unwanted muscle activation in a muscle-specific, temporally modulated manner.

Daskalakis ZJ, Christensen BK, Fitzgerald PB, Roshan L, Chen R.
The mechanisms of interhemispheric inhibition in the human motor cortex.
J Physiol. 2002 Aug 15;543(Pt 1):317-26.
PMID: 12181302

Chen R, Yung D, Li JY.
Organization of ipsilateral excitatory and inhibitory pathways in the human motor cortex.
J Neurophysiol. 2003 Mar;89(3):1256-64. Epub 2002 Oct 30.
PMID: 12611955

Di Lazzaro V, Oliviero A, Profice P, Insola A, Mazzone P, Tonali P, Rothwell JC.
Direct demonstration of interhemispheric inhibition of the human motor cortex produced by transcranial magnetic stimulation.
Exp Brain Res. 1999 Feb;124(4):520-4.
PMID: 10090664

Sailer A, Molnar GF, Cunic DI, Chen R.
Effects of peripheral sensory input on cortical inhibition in humans.
J Physiol. 2002 Oct 15;544(Pt 2):617-29.
PMID: 12381831

Bownds, D
A Neural Signature of Self-Control
Deric Bownd's Mindblog

• "An important but neglected aspect of intentional action involves the decision whether to act or not. This decision process is crucial in daily life because it allows us to form intentions without necessarily implementing them. In the present study, we investigate the neural correlates of intentionally inhibiting actions using functional magnetic resonance imaging. Our data show that a specific area of the fronto-median cortex is more strongly activated when people prepare manual actions but then intentionally cancel them, compared with when they prepare and then complete the same actions....Our results identify a candidate brain area that reflects the crucial decision to do or not to do."

Osmundsen JA
‘Matador’ with a Radio Stops Wired Bull
Modified Behaviour in Animals the Subject of Brain Study
New York Times, 17 May 1965

C. Frank Starmer
Vulnerability of cardiac dynamics
Scholarpedia, 2007, 2(11):1847.

Graphic: Temporal interaction of excitation and inhibition