NTU Undergraduates' research April 2014 - Biosciences | Page 54

Abstract
Cortical representations alter in response to stimulus or a variation from the usual input, for example an experiencedependent activity, like long term potentiation and amputation of forelimbs in monkeys. Organisation and
expansion of connections are a within the cortex are a process that occurs throughout life. The modification of these
cortical representations occur through the alteration of existing lateral connections and the expansion of new ones
into cortical areas, extending receptive field sizes.
Acetylcholine implicates a major effect on this modulation of connections; facilitating cortical synaptic plasticity, in
the motor and somatosensory cortex, along with other neuromodulators noradrenaline, dopamine, serotonin and
histamine. As well as acting with experience dependent activity, to lower the threshold required to induce LTP.
Induction of innervation by acetylcholine has suppressive and excitatory effects, in varying areas, allowing for the
excitation of cortical areas to be specific. Finally acetylcholine effects the spread of excitation throughout the cortex,
which again either suppresses or excites. As acetylcholine has been shown to be a crucial role in all of these
processes, of which mediate lateral connections. These processes effect or initiate how the connections are created
or the induction of their modification, and has also been clearly illustrated that without acetylcholine there is a
majorly direct suppression of the reorganisation of lateral connections and the formation/modification of them.