Basal Ganglia, Thalamus, and Autonomic Nervous System Functions

Basal Ganglia and Motor Control

The basal ganglia are involved in learning and responding to learned associations. Lesions in this area cause diseases such as Parkinson's. The efferent pathways of the putamen are twofold:

• Direct pathway: Projects to the middle and inner segments of the globus pallidus and substantia nigra.
• Indirect pathway: Projects through the lateral or outer segment of the globus pallidus, which has the effect of inhibiting movement.

The Thalamus and Diencephalon

Anatomically, the hypothalamus is part of the diencephalon. This structure, which takes up only 1% of the brain, triggers an array of effector centers such as viscera, exocrine and endocrine glands, and muscles via two routes:

• Neural route: Constituted by the autonomic nervous system (ANS), operating on the smooth muscle of the viscera and exocrine glands.
• Humoral route: Consisting of hormones that can have an excitatory or inhibitory action on an organ.

Functions

• Temperature Control: Regulated by the preoptic region.
• Autonomic Regulation: Managed by the brainstem and spinal cord.
• Sleep-Wake Cycle: Regulated by the autonomic nervous system (neurovegetative system), which operates on viscera, muscles, and glands to modify physiological indicators.

Nervous System Organization

• Central Nervous System (CNS): Brain, cerebellum, thalamus, midbrain, pons, medulla oblongata, and spinal cord.
• Peripheral Nervous System (PNS): Nerves and ganglia.

Circadian Rhythms

• Circadian: Rhythms that occur with a frequency similar to 24 hours.
• Infradian: Rhythms that happen less frequently, with a period longer than 24 hours.
• Ultradian: Rhythms that happen more than once a day (e.g., respiratory cycle, cardiac contraction, food, and drink intake).

Pineal Gland and Sleep

The pineal gland (epiphysis) is located behind the third ventricle, derived from the dorsal diencephalon. It is essential for sleep regulation:

• Non-REM (NREM): Quiet, synchronized sleep without rapid eye movement.
• REM: Appears after 70 to 100 minutes of sleep.

The function of sleep is related to body restitution, facilitated motor learning, and memory consolidation.

Prefrontal Cortex Injuries

Injuries to the prefrontal cortex can produce the following deficits:

• Delayed alternation tasks: Where timing is a key feature.
• Habit formation: Impairment in implementing automated driving habits.
• Emotional conduct: Altered emotional regulation.
• Primary memory: Deficits in short-term tasks managed by the prefrontal cortex, which relies on bioelectric processes.