By L. Jansons
Have you ever found yourself wondering, “what’s my purpose?”. The more we are learning about brain function, the more we are finding the purpose of an organism is to survive, survive via interaction with the environment. At the neurobiological level, we know we act on the environment in one of two ways. We either behave in habitual ways if the environment is known to us, or we respond in a novel ways based on the unique needs of the environment. Therefore, we are either responding in routine ways or novel ways. Cooking breakfast in your own kitchen is quite routine. The motor programs involved in knowing what ingredients are in the cabinet, where the frying pan is, and how to use your own stove are quite automatic. However, if you visit a friend and offer to cook them breakfast or if you are out camping for the first time, the automatic motor progams will not necessarily apply. You’ve encountered a new set of “problems” and will require a slightly new set of motor programs to be able to fry an egg.
Further, behavior processing, or problem solving, occurs in one of two ways. Behaviors elected for survivial are either based on the stimulus based characteristics of the environment or on “higher order” consideration. One can search for a frying pan by opening anything that looks like a cabinet or a container, this would be relying on the stimulus based characteristics of the environment. You quickly open doors until you find yourself in the right cabient. Or one can search by trying to think ahead through the options, “where would someone keep their frying pans, maybe closer to the stove?” or “My matches got wet, what should I do now?”.
Stimulus based processing is quick because the programs already exist, they’ve already been created. After you learn to ride one bicycle you can ride most other bicycles. Higher order processing, in contrast, is slow. You stop to contemplate the possibilitities and sequences. Telling yourself how to ride a unicycle after studying the instructions from a book will be a slower learning process. Stimulus based processing and higher order processing work in tandem to yield the most efficient response.
Procedural learning involves acquisition of a skill through repeated performance and practice, this lies at the heart of automatic responding. There are two subdivisions involved in procedural learning. One, the acquistion of habits and two, adjusting to the environment. The brain system involved in the acuisition of habits is the cortico-striatal system. The second system involved in negotiating the environment is the cortico-cerebellar system.
The fronto-striatal system modulates cognition and behavior in a looped architecture that involves cortex, dopamine reward systems of the basal ganglia, and thalamic output back to the cortex. Ultimately, behavior is selected or inhibited in a gating mechanism mediated by dopamine. In this model, the cortex is considerd dependent on the basal ganglia. This fronto-striatal system includes habit or procedural memory system to benefit from the experience of its activity. Behavior is instrumental, one learns by doing.
The cortico-cerebellar system is primarily involved in the motor adaptation phases of learning. The cerebellum is to learn predictive relationships among sequences of events. The cerebellum functions as a “learning machine” and it regulates the rate, force, and rhythm of behavior, cognition and affect appropriate for context.
Impairment in procedural or instrumental behaviors brings a patient to clinical attention. Those who have difficulty starting, stopping or regulating behavior will seek treatment. In classic movement disorders such as Parkinson’s Disease, hypoactivity of dopamine in the striatum will cause the hallmark “stiff” behavior patterns. Huntington’s Disease is the release of adventitious movement or fragments of motor programs. Damage to the basal ganglia can cause the release or reinstatement of the inhibitions to be erratic and uncontrolled, which results in an awkward start to motion or motions to be unintentionally initiated, or a motion to be halted before, or beyond its intended completion. Researchers have discovered that early motor development is predictive of later cognitive development. Developmental disorders are characterized by difficulty or inability to learn a new routine, implies involvement of instrumental or procedural learning system mediated by the cortico-striatal axis.
Categorization and sequence learning also share procedural learning anatomy. In ADHD, for example, hypofunctioning mesolimbic circuitry would generate altered reinforcement learning and represent sensitivity to reward characteristics of the environment. Lack of reward anticipation results in poor sustained attention, disinhibition and impulsivity.
Procedural learning is essential to our survival and adaptation. It is important to understand behavior from a subcortical view, which reverses the belief that cortex (thoughts) drive our behavior. In fact, not all behaviors essential to adaptation are based upon thinking. Thinking only occurs during the initial phases of certain types of procedural learning tasks and not involved in certain instrumental behaviors.
Source: Subcortical Structures by Leonard Koziol, Psy.D.