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Action potential - excitable cells maintain an electrostatic charge across their insulating cell membrane, with the interior being negative relative to the extra cellular space. An action potential is a cascade reaction, triggered by a depolarisation of the membrane great enough to open ion channels in the membrane, which relieve the electrostatic charge for a few milliseconds. As the action potential is both triggered by and causes depolarisation, it is a self-propagating event which spreads across the entire cell surface. The cell may recover, ready to fire another action potential, thanks to the ion channels' ability to close themselves shortly after opening, limiting the duration of major depolarisation.

Additive - in pharmacology where two drugs act to produce similar effects, with each being equivalent to that added by the other.

Antagonistic - something that reverses the effect of another (agonistic) agent. Potentially something that competes for binding, but does not exert an effect once bound, although other mechanisms exist.

Athetosis - a constant succession of slow, writhing, involuntary movements of flexion, extension, pronation, and supination of the body and limbs.

Choreoathetosis - a combination of choreic and athetoid patterns of movement.

Chorea - marked by incoordination involuntary, jerky movements, especially of the arms, legs, and face.

Competitive - referring to pharmacology, competitive means that a compound will displace another one from a specific binding point.

Cytotoxic - directly damages cells by disrupting their internal functioning.

Deltamethrin (delt) - a Type II pyrethroid commonly used in agriculture. Like other Type II class pyrethroids it produces poisoning symptoms of salivation and choreoathetosis. It acts to prolong the sodium current in excitable cells and to inhibit chloride flow through a subtype of channel.

Dentate gyrus - a part of the hippocampus, found in the core of the brain, deeply involved in self-oriented memory and behaviour. It contains granule cells, excitatory neurons, which receive inputs from areas in the neocortex. Most of these inputs are provided by the perforant path, the axons of spiny stellate cells at the entorhinal cortex. The Dentate gyrus is also one of the few brain areas in which neurogenesis - the birth of new brain cells - occurs in mature organisms.

Electrophysiology - the study of the electrical properties of biological cells and tissues. It involves measurements of voltage differences across cell membrane, and studies of how the flow of electrical current across membranes is regulated. In neuroscience, it includes measurements of the electrical activity of neurons, and particularly action potential activity.
There are two major divisions of electrophysiology: intracellular recording and extra cellular recording. Intracellular recordings are usually (but not always) made from cells in vitro, whereas recordings of activity in living animals (in vivo) are usually extra cellular recordings. Extra cellular recording includes single unit recording, field potential recording, single channel recording and amperometry. Intracellular recording techniques include voltage clamps and current clamps.

Esbiolethrin (esbiol) - a commonly used Type I pyrethroid, producing poisoning symptoms of fine tremor. It prolongs sodium current in excitable cells, although less so than Type II pyrethroids.

Hippocampus - a sea horse shaped neural structure consisting of gray matter and located on the floor of each lateral ventricle. It is intimately involved in motivation and emotion, being a core part of the limbic system, and has a central role in the formation of memories. It is highly preserved between mammals and to some degree in other species.

IC-50 - an indication of the level of induced inhibition in the dentate gyrus. It is the interval in milliseconds between two pulses at which the second pulse results in a spike of half the amplitude relative to the first.

Insecticide - something which kills insects. Extracts of plants like Nicotiana tabacum have been used for millennia to protect crops, commonly being highly neurotoxic to insects but relatively safe for humans.

in vivo - from latin for 'in living body' meaning that experiments are performed on a fully formed organism.

in vitro - from latin for 'in glass' meaning that a preparation has been extracted from a living system to allow finer measurement of its components.

Kolmogorov-Smirnov test - allows comparison of the underlying probability distribution of two sets of data, allowing one to check for normal distribution before performing a T -test.

Lipophilicity - lipo means fat or oil and philicity means love or attraction; literally to love oil, being most energetically stable when involved in Van der Walls interactions, and so partitioning into any area containing hydrocarbon chains.

LD-50 - the dose at which 50% of a species die, considered a benchmark of how potent a toxin is. This '50% of effect' principal is used similarly in EC50s (effective concentrations) and IC50 (inhibitory concentrations).

Mann-Whitney test - a test for correlation, similar to a T test, which works without assumptions of normal distribution.

Paired pulse inhibition - an effect seen in some neural systems, including the perforant path of the hippocampus. In essence the neural network dampens it's own activity dynamically, and this can be seen by applying two stimulations to a small area, then recording the effect on cells in the hippocampus. The result of the second stimulation will be smaller the closer it is to the first, due to an inhibitory effect suppressing the excitability of the neurons.

Paresthesia - a sensation of tingling, pricking, or numbness of the skin with no apparent physical cause, more generally known as the feeling of pins and needles. Usually caused by pressure on a superficial nerve (as in a limb 'going to sleep') but also caused by other factors which affect peripheral neurotransmission.

Perforant path - the major input to the hippocampus, formed of the axonal fibres of neurons mostly from the entorhinal cortex, terminating in the dentate gyrus. Some fibres pass further into the hippocampus, and synapse with pyramidal cells in the CA3 and CA1 layers.

Po - the probability that a channel will be in an open, conducting configuration. Naturally many transient openings and closings take place every second, so the Po offers a way of conceptualising the general trend of channel conductance.

Pyrethroid - any synthetic chemical derived from the pyrethrins. Many analogues to the original six natural chemicals have been created, designed to be more stable in sunlight and to retain their insecticidal properties.

Tail currents - a flow of ions that tails behind the more tightly regulated flows afforded by most membrane channels.

TTX-insensitive - means that the subject, usually a sodium ion channel, is not particularly sensitive to tetrodotoxin (TTX). TTX is a venom from the puffer fish and is an extremely potent blocker of some types of sodium channel.

Voltage sensitive sodium channel (VSSC) - a type of protein that spans the lipid membrane of cells, and selectively allows the flow of sodium ions in response to a depolarisation of the membrane. These are essential for generating action potentials, an important method by which neurons interact. The probability of the channel opening increases as the neuron's membrane potential approaches neutrality. Shortly after any significant opening the channels become unresponsive to the membrane potential (low Po) for a few milliseconds - causing the refractory period.

Welch's T test - a variant of the T test, which tests whether the means of two normally distributed populations are the same. Welch's correction removes the assumption that each population has an equal variance.

Ramon y Cajal - one of the original pioneers in neuroscience, he described the brain and nervous system in exquisite detail, and produced volumes on his findings, which are used to this day.