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Key points
- Many psychotherapies and medications adjust activity of brain networks that evolved long ago and helped early humans survive and reproduce.
- A useful way of thinking about these adaptive brain networks is to compare those involved with "bottom-up" versus "top-down" processing.
- Many child therapies, school and home interventions, and medications can be better understood using this "bottom-up" versus "top-down" framework.
The human brain is a product of evolution. Many psychotherapies and medications focus on adjusting the activity of brain networks that evolved long ago and helped early Homo sapiens survive and reproduce in their physical and social environments. One useful way of thinking about these adaptive brain networks is to compare those involved with "bottom-up" processing with those involved with "top-down" regulation of bottom-up processing.
Bottom-Up Processing
Human brains, like those of other mammals, evolved to quickly and automatically take, process, and respond to sensory information (seeing, hearing, touching, tasting, smelling) about the physical and social world. For early humans, day-to-day safety and longer-term survival depended upon closely monitoring for and quickly reacting to threats and resources. This has been termed bottom-up processing: incoming stimulus data quickly and automatically initiate and direct cognitive, emotional, and behavioral processes.
Bottom-up networks, such as those found in our brain’s limbic system, help detect meaningful stimuli and generate, usually appropriate, emotional responses. These emotional responses then guide, in ways that tend to be quick and automatic, behavioral responses to these stimuli. Fear and/or anger, for example, readies the body for fight or flight. Interest and/or enthusiasm motivates us to focus on and approach useful resources such as food, friends, or mates.
These kinds of quick and automatic responses were, and are, adaptive. See or hear a predator about to attack you? Don’t stop and think but immediately fight or flee instead. You're driving and a ball, followed by a child, darts in front of you? Don’t consider — hit the brakes. See what looks like a fruit tree or termite mound? Move closer — it could be a source of food. See or hear other students doing something in your classroom? Pay attention — it could be an opportunity to socialize.
Top-Down Regulation of Bottom-Up Processing
Human brains, unlike those of most other mammals, evolved to also be able stop and think (and plan) as well as to quickly and automatically react.
Human brains are distinguished by a prefrontal cortex that is much larger, relatively, than those of any other mammal. Top-down networks integrated into the prefrontal cortex include those related to inhibiting and directing automatic responses, including emotional responses, to environmental stimuli. Similarly, executive functioning systems (selective focusing of attention, prioritizing, flexibly shifting attention, multitasking, planning step-by-step actions) are also integrated into the prefrontal cortex. Prefrontal cortex–based "top-down" regulation networks (using knowledge, concepts, expectations, and other cognitive mechanisms) was (for early humans in early environments) and is (for us today) adaptive.
Anticipating and reacting to apparent dangers that are not really dangers? Prefrontal cortex–based top-down regulation systems might help you understand you are safe. Experiencing anger in response to a parent or teacher telling you to do, or not do, something? Think through the consequences of yelling at or defying them and adjust your response accordingly. See something you want? Remember that simply grabbing it out of someone’s hand is a violation of a social norm or that it might be better to purchase it rather than steal it. Want to go out and play with friends or play some video games? Consider that it may be better to get your homework or chores done first, or at least ask permission first, or even stay calm and negotiate — if I do this, can I then do that?
Therapy, Other Psychosocial Interventions, and Bottom-Up Versus Top-Down Processing
Many psychotherapies can be understood as helping children to moderate overactive bottom-up processing and/or strengthen top-down regulation of bottom-up processing.
Relaxation training and exposure therapies help people moderate overly anxious bottom-up processing. Trauma-focused cognitive therapy helps our top-down regulation systems better differentiate between the circumstances of a past assault or injury and current, perhaps safer, circumstances. Assertiveness training helps us practice and prepare to inhibit an aggressive response and replace it with an assertive response. Learning and rehearsing interpersonal problem-solving steps (stop and think, identify multiple ways to respond, choose the best one, and try it) can help top-down systems inhibit impulsive responding.
Classroom and home interventions such as sitting at the front of the room, taking an important test in a separate room, or reading or studying in a quiet place can reduce the amount and intensity of stimuli that elicit bottom-up processing. Prominently placed visual reminders of evening or morning routines and/or prompts and reminders from a classroom aide can augment top-down executive functioning. Rehearsal and reinforcement of desired behaviors can make these more likely to occur (more automatic) than unwanted behaviors.
Psychotropic Medications and Bottom-Up Versus Top-Down Processing
Many psychotropic medications can be thought of as helping to strengthen top-down regulation of bottom-up processing.
Benzodiazepines, for example, augment the effects of a major inhibitory neurotransmitter (gamma amino-butyric acid or GABA) and can help attenuate the salience network’s capability of generating fear-spectrum emotions. Selective serotonin reuptake inhibitors (SSRIs) tend to dampen the reactivity of a key part of the anxiety system, the amygdala, by increasing levels of the neurotransmitter serotonin in inhibitory systems.
Psychostimulants prescribed for ADHD are dopamine re-uptake inhibitors. Psychostimulants increase levels of the neurotransmitter dopamine in brain synapses. Dopamine helps govern the activation of the prefrontal cortex, and, as discussed above, the prefrontal cortex is very involved in top-down regulation of bottom-up processes. Increasing dopamine levels in brain synapses moderately increases the activation of the prefrontal cortex and can improve top-down executive functions such as focusing and attending, organizing, prioritizing, and problem solving.
Bottom-Up Versus Top-Down Processing and Neurodevelopmentally Atypical Children
Many neurodevelopmentally atypical children struggling at school, at home, or in the community can be viewed as exhibiting overactive bottom-up processing (e.g., excessive anxiety or anger, excessive reactivity to social stimuli) and/or underactive top-down processing (e.g., emotional control and executive functioning). Therapy, classroom-based, and home-based psychosocial interventions, as well as many medications, can be understood as helping these children by moderating overactive bottom-up processing and/or strengthening top-down regulation of bottom-up processing.
This "bottom-up versus top-down processing" framework can help parents better understand why mental health and school professionals might recommend therapy, classroom-based, and home-based psychosocial interventions and/or medication approaches for promoting their children’s adjustment and growth.
References
Patterson, J., Griffith, J. L., & Edwards, T. M. (2021). The Therapist's Guide to Psychopharmacology: Working With Patient, Families and Physicians to Optimize Care. New York: The Guilford Press.
