Basics of Functional Neuroanatomy

Basics of Functional Neuroanatomy Notes

Overview of the Brain

• The adult human brain weighs approximately three pounds and consists of about 100 billion neurons.

• It has roughly 100 trillion synapses, forming complex neural circuits responsible for various functions.

Brain Stem

• Components: Medulla oblongata, Pons, Midbrain, Reticular formation

• Functions:

  • Houses vital survival programs such as

  • Breathing

  • Heartbeat regulation

  • Pain perception

  • Consciousness

  • Medulla Oblongata:

  • Manages autonomic functions (heart rate, circulation, and breathing)

  • Acts as a crossover point for nerve connections

  • Pons:

  • Relays signals from the forebrain to the cerebellum

  • Involves functions related to sleep, respiration, swallowing, and bladder control

  • Midbrain (Tectum and Tegmentum):

  • Tectum: Involved in visual (superior colliculus) and auditory (inferior colliculus) processing

  • Tegmentum: Responsible for motor control, eye movements, and pain perception

  • Cerebellar peduncles connect the forebrain to the midbrain, carrying motor commands

Cerebellum

• Essential for proper motor function, learning, and motor memory.

• Effects of Damage:

  • Limb coordination loss if lobes are damaged

  • Balance problems if nodes at the bottom are affected

  • May play a role in cognition, particularly in attention and working memory

Subcortical Structures

1. Hypothalamus:

   • The brain’s master regulatory structure

   • Regulates body functions (temperature, rhythms, blood pressure, glucose levels)

   • Involved in motivated behaviors (thirst, hunger, aggression)

2. Thalamus:

   • Serves as the gateway to the cortex for all sensory information (except smell)

   • Organizes and relays incoming sensory data

   • Partially shuts down during sleep to minimize incoming sensations

3. Hippocampus:

   • Critical for the formation of new memories

   • Grows larger with increased use; important for spatial navigation and memory arrangement

4. Amygdala:

   • Connects external stimuli with emotional responses (not limited to fear)

5. Basal Ganglia:

   • Crucial for planning and producing movement

   • Damage can result in tremors, rigidity, and impaired learning of motor habits

   • Contains the nucleus accumbens, associated with reward and motivation

The Cortex

• Cerebral Cortex:

  • Outer layer of the cerebral hemispheres responsible for thoughts, perceptions, and complex behaviors

  • Divided into two hemispheres connected by the Corpus Callosum

• Four Major Lobes:

  1. Occipital Cortex:

  • Responsible for vision

  • Converts light into perception

  1. Parietal Cortex:

  • Handles touch, spatial sense, navigation, and attention

  1. Temporal Cortex:

  • Involved in hearing, memory, and language comprehension (Wernicke’s area)

  1. Frontal Cortex:

  • Responsible for reasoning, planning, and complex cognitive tasks

  • Contains the Prefrontal Cortex, crucial for social behaviors and decision making

  • Historical context: Lobotomy was used to treat mental illness but often resulted in emotional flatness and disconnection from social interaction

Directional Terms in Neuroanatomy

• Rostral (anterior): Front of the brain

• Caudal (posterior): Back of the brain

• Dorsal (superior): Above or toward the back

• Ventral (inferior): Below or toward the front

• Medial: Towards the Midline

• Lateral: Away from the Midline

Visual and Auditory Processing

• Primary Visual Cortex:

  • Organized according to spatial mapping; responds to visual stimuli in the contralateral hemifield

• Primary Auditory Cortex:

  • Organized based on frequency processing; information from cochlea is processed in specific areas

Advanced Cognitive Functions

• Dorsolateral Prefrontal Cortex (dlPFC):

  • Key in attention, cognitive functions, working memory, and decision-making

• Ventrolateral Prefrontal Cortex:

  • Involved in language production (Broca’s area) and inhibitory control

• Posterior Parietal Cortex (PPC):

  • Involved in spatial attention and memory retrieval; connections with the default mode network

• Anterior Cingulate Cortex (ACC):

  • Important for error monitoring, attention allocation, and decision-making

These foundational concepts in neuroanatomy are critical for understanding brain function and the impact of structural damage on behavior and cognition.