Sensory Issues

Автор: Pete van Deusen
Источник

Sensory inputs are supposed to be screened through the thalamus, which, in concert with the pre-frontal cortex, filters what is sent to the cortex to be processed, and blocks material that is not considered necessary. When this function fails, or is too weak to do its job in situations of greater sensory load, the client’s sensory integration and association areas can be overloaded by chaotic inputs, resulting in what we see from the outside is extreme sensitivity. This could appear in the EEG as excessive slow wave activity in the prefrontal areas, and/or it can appear as low levels of sensorimotor rhythm (SMR) relative to theta in the sensorimotor cortex (C3, Cz, C4). Neurons in the sensorimotor cortex (SMC) receive inputs from rhythm generating sets of nucleii in the thalamus, some of which produce 4-6 Hz theta, some 8-10 or 10-12 Hz alpha and some 12-15 Hz SMR. It appears that when the SMC neurons are linked to the slower generators, they are not as activated and don’t do their job as well. When they are dancing to the rhythm of the faster generators, the thalamus is more active in its screening function. Hence we often train in the SMC to increase SMR and decrease theta activity to wake it up.

High levels of coherence, especially in faster frequencies like 12-15 Hz, 15-18 Hz or above, can also show up as sensory sensitivity when they appear in the temporals, parietals, SMC or occipitals–essentially toward the back of the brain, where sensory information is processed. For example, when a person is having a migraine and experiencing light sensitivity, we will often see high fast wave coherence in the occipital lobes. In these cases, the pools of neurons which should be working independently tend to get locked together so they are all doing the same thing at the same time and an overload results.