Memory, Consciousness, Intellect, Behavior, and the Stress Response

Working Memory and Goal-Directed Behavior

Working memory is defined as the system that maintains goal-relevant information for a short period of time. It is an essential component for several cognitive processes, including language, problem-solving, mental navigation, and reasoning. The anatomical substrates for working memory primarily involve the Lateral Prefrontal Cortex (LPFC), which is responsible for executive function, and the Temporoparietal Association Cortex (TPAC).

Goal-directed behavior is managed through specific frontal lobe "loops." The Goal-Directed Behavior Loop, also known as the lateral prefrontal loop, is associated with the "temples" area of the forehead. This loop follows a specific procedural sequence: first, a goal is decided upon; second, a plan or "action steps" are created to accomplish that goal; third, the plan is executed; and fourth, the success of the plan is monitored. This sequence essentially constitutes the process of making decisions.

Damage to the goal-directed loop results in specific clinical signs. These include impaired working memory, difficulty dividing or switching attention, difficulty setting goals, and significant challenges in creating action steps to achieve goals. Additionally, individuals may exhibit impaired "divergent" thinking, which hampers creative problem-solving.

Declarative Memory and the Processing Stages

Declarative memory, often referred to as "explicit" memory, involves facts, events, concepts, and locations. Practice is essential for both the creation and maintenance of these memories. Declarative memory is further divided into two categories: Episodic memory, which relates to specific personal events (such as having dinner with friends), and Semantic memory, which consists of common knowledge not based on personal experience (such as knowing the names of the different lobes of the brain).

There are three distinct stages in the formation and use of declarative memory:

  1. Encoding: This is the process of forming a mental representation of what we want to remember. Encoding is enhanced by paying attention, emotional arousal, linking new information to existing knowledge, and reviewing material.
  2. Consolidation: This stage stabilizes the memory through synaptic remodeling, such as Long-Term Potentiation (LTP). This process primarily occurs in the Medial Temporal Lobe (MTL), specifically the hippocampus, and involves other brain areas as needed for specific memories. Sleep is explicitly identified as essential for this stage.
  3. Retrieval: This is the process of accessing stored information. The Lateral Prefrontal Cortex (LPFC) is the structure that initiates retrieval.

Anatomically, declarative memory processing involves the Medial Temporal Lobe (MTL), which includes the medial temporal cortex and the hippocampus, the Temporoparietal Association Cortex (TPAC) for perceptual integration, and the Lateral Prefrontal Cortex (LPFC) for the organization and categorization of information. Disorders of declarative memory are referred to as Amnesia, which can be Retrograde (loss of old memories) or Anterograde (inability to form new memories).

Procedural Memory: Learning, Storage, and Adjustment

Procedural memory, involving skills and habits, is termed "implicit" memory because it cannot easily be put into language. Like declarative memory, practice is essential for its creation and maintenance. It progresses through three stages: the Cognitive stage ("what to do"), the Associative stage ("how to do it"), and the Automatic stage ("do it" without conscious thought).

Learning procedural skills involves several brain regions: the Frontal Lobe (including all three loops), the Basal ganglia, and the Parietal lobe (TPAC). Specifically, it engages the Medial Prefrontal Cortex (MPFC) for emotions and motivation, the Ventral Prefrontal Cortex (VPFC) for social behavior, and the Lateral Prefrontal Cortex (LPFC) for executive function. Storage of procedural memories is primarily handled by the Basal ganglia, the Supplementary Motor Area (SMA), and the wider Frontal lobe. Adjustments to these movements and skills are facilitated by the Cerebellum, Frontal cortex, Basal ganglia, TPAC, and the Motor cortex.

Emotions, Awareness, and Motivation

The Medial Prefrontal Cortex (MPFC), located near the "forehead," manages the Emotion Loop. This loop regulates emotions, motivation, reward-seeking behavior, and the ability to make predictions when an outcome is uncertain. It is also responsible for integrating internal emotions with external facial expressions.

Signs of damage to the emotion loop include apathy, a loss of initiative, and the loss of a "gut feeling" regarding danger. Patients may also experience a loss of spontaneous thought and loss of emotional responses. One specific symptom is Emotional Lability, which is characterized by abrupt mood shifts and involuntary, inappropriate emotional expressions in the absence of subjective emotion, often triggered by nonspecific stimuli.

Social Behavior and Decision-Making

The Ventral Prefrontal Cortex (VPFC), located in the "supraorbital" region, manages the Social Behavior Loop. This loop allows an individual to recognize social cues (often described as "reading the room"), regulates self-control, and parses relevant information from irrelevant information. In a normal state, the social behavior loop acts as an action selection system that is rational, balancing the reward-seeking system which is primal, impulsive, and seeks immediate gratification.

Damage to the social behavior loop leads to disinhibition, a lack of concern about consequences, impulsiveness, and inappropriate social behaviors. Like the emotion loop, damage here can also lead to emotional lability.

Consciousness and Attention

Consciousness involves several aspects regulated by specific neurotransmitters:

  • General level of arousal: Regulated by Serotonin.
  • Attention: Regulated by Norepinephrine.
  • Selection of the object of attention (based on goals): Regulated by Acetylcholine.
  • Motivation and initiation of activity: Regulated by Dopamine.

Attention is fundamentally limited; information that is not attended to is not processed. Attention is also limited by the amount of mental effort available. There are five distinct types or limits of attention:

  1. Orienting Attention: The ability to locate specific sensory stimuli among many competing stimuli.
  2. Selective Attention: The ability to attend to important stimuli and ignore distractions.
  3. Sustained Attention: The ability to continue an activity over time.
  4. Divided Attention: The ability to attend to multiple aspects of the same task simultaneously.
  5. Switching Attention: The ability to attend to multiple aspects of different tasks simultaneously.

It is noted that cognitively, it is simply not possible to "multi-task" in terms of processing multiple high-level tasks at once. Loss of consciousness is typically the result of trauma or pressure on the brain.

Stress Response and Psychological-Somatic Interaction

When a threat is perceived (e.g., being threatened by a bear), the body initiates a "fight or flight" autonomic response involving the Hypothalamus-Pituitary-Adrenal (HPA) axis. This axis triggers the release of cortisol from the adrenal medulla to provide hormonal support for the stress response.

The effects of cortisol include mobilizing energy in the form of glucose, suppressing the immune system, activating the anti-inflammatory system, and turning on "memory maker" cells in the hippocampus.

However, chronic stress and persistent cortisol levels lead to negative health outcomes, including increased blood sugar, immunosuppression, and cardiovascular changes that can lead to heart attack or stroke. Pathologically, chronic stress can damage the cells of the hippocampus and weaken or break the social behavior loop. In a dysfunctional psychological-somatic state, the frontal lobe link is broken, the amygdala becomes hypersensitive and overreacts to perceived threats, and the frontal lobe is less able to ensure a socially appropriate response.", "title": "Memory, Consciousness, Intellect, Behavior, and the Stress Response"}