Neuroanatomy Terminology and Brain Structures

Hand vs. Dorsal Fin
- The speaker struggles with anatomical terms like "dorsal fin" but finds it helpful to remember these terms through association or visualization.
- Dorsal relates to the back (e.g., dorsal fin on sharks) while ventral relates to the belly.
Anatomical Orientation
- Dorsal: Back
- Ventral: Belly
- Medial: Towards the midline
- Lateral: Towards the sides
- Anterior: Front (from head to tail)
- Posterior: Back (tail end)
Application
- The speaker uses a doodle of a dog in a shirt to illustrate these terms by showing medial (nose between eyes) and lateral (sides).
- Mention of how these terms can illustrate a cat's anatomy while discussing orientation in four-legged versus upright organisms (humans).

Cervical Flexure
- In humans, the spinal cord and brain exhibit a bend (cervical flexure) during early development which influences anatomical orientation.
- This results in dorsal being at the top of the head (back) for humans, while ventral represents the belly.
Maintaining Directional Consistency
- The speaker discusses how medial/lateral does not change between four-legged (cats) and upright (humans) animals.
- Highlighting the changes in how we view dorsal and ventral orientations in different species due to the spinal flexure.

Types of Planes
- Horizontal: Parallel to the ground. A horizontal section looks at the brain from a top-down perspective.
- Frontal (Coronal): Cuts through the body from front to back, separating anterior from posterior.
- Sagittal: Vertical section that separates left from right hemispheres; this includes the midsagittal plane, which bisects the brain down the middle.
Importance of Understanding Planes
- Knowing the views (dorsal, ventral, lateral) is critical when analyzing brain slices and images in studies.
- Clarification on when to use terms and how to ask during labs if unsure about a section's orientation.

Spinal Cord Structure
- The spinal cord integrates sensory and motor information and is part of the central nervous system.
- In cross-section, the spinal cord resembles a butterfly with sensory information entering from the dorsal part and motor information exiting from the ventral area.
Dorsal Horn vs. Ventral Horn
- Sensory nerves originate from the dorsal root ganglia (unipolar neurons) which hold the cell bodies of sensory neurons.
- The ventral root carries motor information outwards from the spinal cord.
Nerve Types
- Spinal nerves are mixed nerves, containing both sensory and motor fibers.
- Afferent refers to sensory signals entering the CNS, while efferent pertains to motor signals exiting the CNS.

Basic Spinal Reflexes
- Example: Knee-jerk reflex is a monosynaptic reflex requiring no conscious thought, demonstrating rapid reflex actions.
- Reflex Pathway: Sensory input conveys that a muscle has stretched, leading to a contraction message from interneurons in the spinal cord.
Walking and Spinal Pattern Generators
- Spinal networks help coordinate muscle activity for walking, learned through practice.
- Coordination patterns are established in the spinal cord and contribute to locomotion without conscious thoughts.

Defining Dorsal and Ventral
- Convention places dorsal above ventral within the anatomical model to avoid confusion.
Gray Matter vs. White Matter
- Gray matter: Contains cell bodies of neurons, notably motor neurons and interneurons.
- White matter: Comprises axon tracts that connect various brain regions.
Reflex Nerves
- Dorsal roots are synonymous with afferent nerves that convey sensory information, while ventral roots correspond to efferent nerves relaying motor commands.

Main Brain Regions
- The brain is organized into three primary regions: forebrain, midbrain, and hindbrain.
- Forebrain (Telencephalon): Cortex or outer layer of the brain.
  - Functions include higher-level cognition and processing.
- Midbrain: Connects various auditory and visual reflexes and processes.
- Hindbrain: Comprising the brainstem (medulla, pons) and cerebellum.
Developmental Aspects of the Brain
- The forebrain includes the prosencephalon, mesencephalon (mid), and rhombencephalon (hind); focused on early development and how these embryonic sections define adult structures.

Medulla Oblongata: Regulates basic life functions (heart rate, respiration).
Pons: Involved in sleep, respiration, swallowing, and relaying signals between different parts of the brain.
Cerebellum: Associated with balance, motor control, learning new motor tasks. About 50% of brain’s neurons are contained here.
- Plays a crucial role in things like driving or playing an instrument by refining motor functions.
Thalamus: Major relay center for sensory information (excluding smell) before the cortex.
Hypothalamus: Controls various autonomic functions such as hunger and thirst regulation, and connections to the endocrine system (pituitary gland).

Limbic System: Interconnected with the hypothalamus, important for emotional responses, survival behaviors (fight, flight, feeding).
Basal Ganglia: A set of nuclei important for movement, reward pathways (though named "ganglia", they are composed of nuclei in the brain).
Addictive Behaviors: Related to the brain's reward system, reinforcing behavior crucial for survival.

Large Scale Brain Networks: Involve multi-region interactions, defining behaviors beyond isolated functions.
- Default Mode Network: Active during daydreaming or self-referential thinking, independent from task performance.
- Central Executive Network: Engaged during focused cognitive tasks.
- Salience Network: Helps reorient attention and switch between cognitive networks in response to environmental stimuli.
Conclusion: The lecture provides an extensive overview of neural anatomy, emphasizing connections between regions and their functional interactions in various behaviors, and encouraging a focus on broader comprehension rather than rote memorization.
Future Topics: Connections between structures will be examined in depth regarding various cognitive processes and behavioral aspects in upcoming classes.