I have the impression that central aspects of brain functioning are: 1. parallel processing, 2. multistage elaboration, 3. answer competition, 4. pleiotropism and 5. plasticity.

In simple words:

[Parallel processing] -- every bunch of information is simultanously "sent" to a high number of processing modules, which process it almost independently, each according to its specific "algorithms", dictated by its circuitry (synaptic connections and their static and dynamic efficiency - see below, plasticity)

[multistage processing] -- the outputs of these elaborations are combined in many ways and in turn "sent" to a high number of further processing modules, which process it .... as above .... (and so on).

[answer competition] -- at difference with all current computer algorithms, every brain circuit continuously receives input from other circuits (reflecting both external signals and internal activity), which act as "proposed" intermediate results / interpretations / reactions. So, each stage of elaboration constitutes a continuous re-examination of "competing" inputs. The "strength" of each input to every module, and of its output in the "competition" for further stages of elaboration, continuously varies in time as a result of possibly varying sensory inputs, of the ongoing elaboration at each upstream stage, and of the emotional valence that limbic areas attribute to each "proposed" intermediate result / interpretation.

NOTE THAT EVERY HIGH MENTAL FUNCTION MUST USE A HUGE NUMBER OF THESE MODULES AND WILL ACTUALLY SHARE MOST OF THEM WITH OTHER MENTAL FUNCTIONS -- THIS IS AT DIFFERENCE WITH ANY "ORGAN" METAPHOR.

[pleiotropism] -- similar elaborations are performed by distinct cerebral areas in such a way that a lesion can often be overcome by the vicariating activity of other areas, with resulting qualitative changes in the elaboration and its results, but possibly a similar overall performance.

[plasticity] -- every single bit of information which is processed by neural circuits not only influences their activity and is thus elaborated, but it also introduces - in a complex relation with every other aspect of the momentary activity - slight changes in biochemical regulations in each involved neuron and synapse, with the result that synaptic efficacy (and even neuronal and synaptic structure) is continuously modulated, partly in a reversible way, partly in long-term or irreversible ways.

THIS VICARIATING ABILITY (ARISING FROM PLEIOTROPISM AND PLASTICITY) ALSO MAKES THE "MULTI-ORGAN" METAPHOR QUITE WEAK IN DESCRIBING BRAIN / MENTAL FUNCTIONS.

Thus, (1) each sub-network is continuously and plastically modified by the information that it elaborates; (2) each sub-network continuously re-examines its inputs (which are bound to continuously change even in the absence of external stimuli); (3) the output of many sub-networks continuously contribute (in terms of a time-varying mutual reinforcement or competition) to the elaboration by many downstream sub-circuits; (4) many "solutions/answers" are simultaneously present ("proposed") at every moment in the brain; (5) a central feature of brain, at difference with current AI algorithms, is the need for continuous "trimming" of less relevant "proposed results/answers", at each ntermediate stage of elaboration, up to the executive functions of consciousness and behavioral planning, which can only consider a ridiculously minimal portion of all the intermediate results that cerebral elaboration of information has produced.