efferent*). AGONIST – A neurotransmitter or a drug which binds to a receptor and triggers a cascade of intracellular signalling leading to changes in the membrane potential. AMINO ACID – A chemical made of carbon, oxygen, hydrogen and nitrogen, which is a building unit of all proteins* and other biologically important substances. AMINO ACID NEUROTRANSMITTERS – A group of fast acting neurotransmitters* which includes glutamate (excitatory) and GABA (gamma-amino butyric acid, inhibitory). AMNESIA – Loss of memory. AMYGDALA – A structure in the forebrain which is a component of the limbic* system. It is implicated in control of emotions. ANTAGONIST – A chemical which blocks receptors* and stops (inhibits) the effects of agonists*. ANTERIOR – Towards the front, e.g. anterior cingulate cortex – frontal part of the cingulate cortex (part of the brain).
evoked a particular reflex response. Results- there had to be conduction across at least 2 neurons a sensory neuron from skin receptor and motoneuron that acticates muscle fibers. · Spatial summation- several neurons may funnel in upon one output. Stimuli applied to dirfferent points in the saddle area will not evoke a reflex if presented seperately, byt they will if presented simultaneously. The excitatory effects from different regions are all funneled into the same common path. · Temporal summation- a subthreshold stimulus will not elicit the reflex but 2 or more will if presented successivley at intervals of up to half a second Inhibition- neuron can receive both excitatory and inhibitory messages. Two processes summate algebralically; they pull in opposite directions and thus have opposite signs/positive-negative/ The Synaptic Mechanism:
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