Subcortical Structures of the Forebrain

The forebrain is the largest and most evolutionarily recent part of the brain, containing both the cortex and subcortical structures.

The brain is divided into three major parts:
- Forebrain
- Midbrain (blue on the diagram)
- Hindbrain (green on the diagram)

Subcortical structures are complex and have three-dimensional shapes that pose difficulty in representation on two-dimensional images.

Location: Central part of the brain, symmetrical in both hemispheres.
Function: Responsible for the planning and initiation of intentional movements.
- Role: Unlike the cerebellum, which is involved in precision, the basal ganglia determine which muscles to activate for a voluntary movement (e.g., reaching out).
Note: The basal ganglia consist of multiple substructures, but detailed examination is beyond this topic.

Description: Egg-shaped structure located medially, closer to the center of the brain than the basal ganglia.
Function: Acts as the central relay station for sensory information:
- Nearly all sensory information (except for smell) passes through the thalamus before reaching specialized processing areas in the cortex.
- Filtering and preliminary processing of sensory information occurs in the thalamus.

The limbic system is crucial for emotional processing and memory, involving several structures:

Description: Small, egg-shaped structure, often obscured in images (appears in yellow).
Function: Regulates internal bodily functions:
- Regulates essential physiological processes like body temperature, hunger, and the four "F's" (feeding, fighting, fleeing, and mating).
Significance of Research: Brain damage studies (e.g., experimental lesions in lab rats) show the hypothalamus's role:
- Example: A rat with a lesion in the hypothalamus fails to regulate hunger, leading to constant eating behavior.

Description: Bulb-like structure hanging at the bottom of the brain.
Function: Regulates hormones released by various glands throughout the body:
- Hormones influence numerous bodily functions and behaviors (e.g., adrenaline from the adrenal gland increases arousal and alters blood flow).
- Does not require memorization of specific hormones or gland functions for this overview.

Function: Plays a vital role in spatial navigation, memory formation, and the creation of new memories:
- Responsible for forming new memories, which are gradually transferred over months to other brain regions for long-term storage.
- Detailed studies on memory processes involving the hippocampus will be discussed in cognition modules.

Description: Small structure located anterior to the hippocampus, often likened to an almond in shape.
Function: Involved in emotional processing, especially concerning threats:
- Monitors sensory input for signs of danger and contributes to emotional responses and memories related to threats and fear.
- Example Demonstration (with images): Participants often fail to notice neutral items (e.g., shoes, keys) but are quick to recognize threatening images (e.g., snakes, spiders) due to evolutionary adaptations for survival. The amygdala's role in this rapid recognition is emphasized.

The discussion covered several significant subcortical structures and their specialized functions, setting the stage for a deeper exploration of the cortex in subsequent materials.