Brain Stem

The lower part of the brain where it connects to the spinal cord. The basic functions for survival are located in the brainstem: breathing, digestion, heart rate, blood pressure and for arousal (being awake and alert). The brainstem is the pathway of the cranial nerves from the spinal cord to the higher parts of the brain.

Basic life maintenance functions, e.g, nervous control of respiration, blood pressure, and heartbeat. Reticular Activating System (within medulla) controls wakefulness and alertness

Damage leads to global disorders of consciousness, e.g., drowsiness, somnolence, stupor, coma or sometimes death

Medial Medulla

• Medial medullary syndrome or Dejerine Syndrome (Medial medullary stroke: report of seven patients and review of the literature. Neurology 1997 Apr;48(4):882-90.)
• Medial medullary infarct is associated with clinical triad of
• ipsilateral hypoglossal palsy
• contralateral hemiparesis
• contralateral lemniscal sensory loss
• Variable manifestations may include isolated hemiparesis, tetraparesis, ipsilateral hemiparesis
• Ipsilateral or Contralateral facial palsy, ataxia, vertigo, nystagmus, dysphagia. Palatal and paryngeal weakness rare in pure MMI, common in lateral medullary infarct

Pons and Cerebellum - The Cerebellum helps coordinate movement both balance and muscle coordination

• Ataxia which is a problem of muscle coordination.

Correlation of postural and kinesthetic (muscle movement) data - Damage leads to movement disorders involving

• Fine motor control
• Coordination
• Postural regulation

Midbrain - Correlation of sensory and motor centers; Integration of reflex & automatic responses involving the visual and auditory system. Damage leads to specific movement disorders, e.g.,

• certain types of tremor
• rigidity
• extraneous movements of local muscle groups

Thalamus - Major sensory correlation center. Participates in exchanges between higher and lower brain structures, between sensory & motor or regulatory components at same level, and between cerebral cortical centers at highest levels function. Regulation of cortical activity via focusing & shifting attention as well as modality-specific alerting functions

• Damage of Left thalamus may lead to decreased verbal fluency, speech spontaneity, verbal memory and learning disorders
• Damage to Right thalamus may lead to decreased face/pattern recognition, pattern matching, maze tracing
• Bilateral lesions may lead to general intellectual loss, gross memory problems, emotional apathy and development of mutism

Hypothalamus - Regulation of physiologically-based drives, e.g., appetite, sexual arousal, thirst. Physical protection behavioral patterns, e.g., fear, rage. Regulation of autonomic functions, e.g., weight, temperature, some mood states. Damage leads to obesity, disorders of temperature control, changedDamage to mamillary bodies leads to anterograde and some retrograde amnesia (usually as a result of alcoholism) appetitive drive (e.g., sexual arousal loss or hyper sexuality)

Limbic System

• Hippocampus is involved in the long-term storage of perceptions in memory
• Bilateral damage to hippocampus leads to massive anterograde and some retrograde amnesia for declarative (not procedural) memories
• Unilateral damage of hippocampus leads to expected types of memory storage and retrieval problems, i.e., left damage with verbal data and right damage with nonverbal data.
• Mamillary Bodies are also involved in the long-term storage of memories
• Hippocampus-Amygdala-Uncus (and Temporal Lobe) is involved in emotional behaviour

  • Damage leads to disturbances and alterations in subjective feeling, bizarre posturing, obsessional thoughts, initiation of elaborate, stereotyped, complex motor behaviors

References

Medulla (Kolb & Whishaw, 2003)