Avoiding Generalizations

The physical boundaries of the left and right brains must not be taken too
seriously. We are ultimately concerned more with the types of processing
that goes on in the brain — whether bottom-up (starting from parts) or top-
down (starting from the whole) rather than their physical locations. The
split-brain experiments show that if the two hemispheres are not connected
into a single circuit — that is, if they do not speak to each other — they ex-
ist essentially as two major circuits. Only the circuit connected to the lan-
guage centre seems to result in conscious awareness. Hence, in split-brain
patients, the right brain functions do not enter into consciousness directly
since it is not connected to the (conscious) left brain. However, it should be
noted that the two brains can speak to each other on another level that does
not require the corpus callosum. They can also speak to each other via the
limbic system (through the thalamus and hypothalamus) and the autonomic
nervous system.