Cognitive brain functions including sensory perception and control of behavior are ascribed to computation in networks of neurons. In each biological neuron, dendrites receive and integrate synaptic inputs to a threshold for axonal firing as output. Even though the behavior of an actual biological neuron is quite complex, in replicating complex behaviors, neurons are frequently modeled as simple integrate-and-fire neurons. Neuronal firings and their chemical synaptic transmissions are presumed to act like “bit states” in silicon computers. Information flows directionally through landscapes of integrate-and-fire neurons in feed-forward and feedback networks, accounting for various forms of brain cognition. However, cognition and consciousness may, or may not, coincide. Complex behaviors like walking or driving are at times non-conscious autopilot functions and at other times accompanied by conscious perception and control. For example, we may drive to work on non-conscious autopilot while daydreaming—our conscious minds roaming elsewhere. But if a horn sounds or a light flashes, our conscious mind returns to conscious perception and control. Studies of stimulus-independent thought (“mind wandering”) show activity literally moving around the brain as the content of consciousness changes.

In the context in which it appears, “ascribed” most nearly means

A. inscribed
B. attributed
C. compared
D. allowed
E. imparted



The author of the passage mentions “autopilot functions” primarily in order to

A. argue that computation models of neuron behavior are oversimplified
B. suggest an alternate explanation for the behavior of dendrites
C. provide an example of neuron-produced computation that coincides with consciousness
D. cast doubt on the theory that cognition and consciousness are necessarily linked
E. warn against the dangers of non-conscious behavior



Which of the following can be inferred based on the information provided in the passage?

A. The behavior of neurons is too complex to be realistically modeled.
B. Early neuroscientists primarily compared brain functions to computer processes.
C. At least some of the time, sensory perception occurs during consciousness.
D. A dangerous stimulus is required for a rapid shift from autopilot behavior to consciously controlled behavior.
E. Humans are unable to go without daydreaming for more than a few hours at a time.