PSYC1003-(01) Lectur-audio

Introduction to Neuroanatomy

Nervous System Overview

• The nervous system is an intricate network comprising neurons and glia (glial cells).

• Neurons are the primary functional units that receive, process, and transmit information through electrical and chemical signals. They facilitate communication within the nervous system and throughout the body.

• Glial cells, on the other hand, provide support and protection for neurons. They perform various roles including maintaining homeostasis, forming myelin (which insulates axons), and participating in the repair of nervous tissue.

Review of Neuron Function

Resting and Action Potentials

• Neurons typically maintain a resting membrane potential of about -70 mV until stimulated. When a stimulus exceeds a certain threshold, it triggers an action potential, a rapid change in electrical charge that travels along the axon.

Neurotransmission

• Neurons communicate with one another at junctions called synapses. Neurotransmitters are released from the axon terminal of the presynaptic neuron into the synaptic cleft, where they bind to receptors on the postsynaptic neuron to propagate or inhibit the signal.

Course Update

Lab Requirements

• Students are required to bring colored markers/pencils for drawing activities that will supplement their understanding of neuroanatomy through visual representation.

Navigating the Brain

Directional Terms

• Anterior: Refers to the front of the brain and body, often associated with the face region.

• Posterior: Indicates the back of the brain and body.

• Superior: Describes a position above another part of the body.

• Inferior: Indicates a position below another part.

• Lateral: Means toward the side of the body, as seen in relation to the ears.

• Medial: Refers to being closer to the midline of the body.

Planes of the Body

• Coronal Plane: A vertical plane that divides the body into anterior and posterior parts, viewed from the front or the back.

• Sagittal Plane: A vertical plane that divides the body into left and right parts, viewed from the side. A midsagittal section gives equal left and right halves.

• Horizontal Plane: Also known as the transverse plane; it divides the body into superior and inferior parts, viewed from above or below.

Brain Views

• Sagittal View: Provides a side perspective of the brain, displaying structures from anterior to posterior and superior to inferior.

• Coronal View: Offers a front-facing perspective, showcasing the separation of brain structures and facilitating understanding of their arrangement.

• Horizontal View: Illustrates a top-down view of the brain, helpful in visualizing the layout of various regions.

Important Terminology

• Proximal: Closer to a reference point or origin, often used in relation to limbs.

• Distal: Further from a reference point; often describes positions along limbs.

• Ipsilateral: Refers to structures on the same side of the body.

• Contralateral: Indicates structures on opposite sides of the body.

Structure of the Brain Overview

Major Regions

• Forebrain: Responsible for complex behaviors and higher cognitive functions, including thinking, planning, and decision-making.

• Midbrain: Positioned between the forebrain and hindbrain; essential for sensory processing and motor control, playing a pivotal role in reflex actions.

• Hindbrain: Controls basic life-supporting functions such as breathing and heart rate, as well as involuntary actions like digestion.

Forebrain Components

• Cerebrum: The largest part of the brain; consists of two hemispheres (left and right) divided by the longitudinal fissure and responsible for voluntary actions, thought, and memory.

• Thalamus: Acts as a relay station for sensory information, processing and transmitting data to the appropriate areas of the cerebral cortex.

• Hypothalamus: Regulates homeostasis, hormonal balance, and autonomic functions, effectively orchestrating bodily responses.

• Limbic System: Involved in the regulation of emotions and formation of memories, incorporating structures such as the hippocampus and amygdala.

Midbrain Components

• Tectum: Part of the midbrain; involved in sensory processing, with important components including:

  • Superior Colliculus: Primarily associated with visual processing and coordination of eye movements.

  • Inferior Colliculus: Critical for auditory processing and localization of sounds.

• Tegmentum: Contains several nuclei, including those regulating movement and pain modulation.

• Substantia Nigra: A key region producing dopamine, crucial for motor control and reward pathways.

Hindbrain Components

• Medulla Oblongata: Controls vital autonomic functions such as heart rate and respiration; located at the base of the brainstem where it connects to the spinal cord.

• Pons: Serves as a relay station for information between the cerebellum and the cerebral cortex, also assisting in regulation of sleep and arousal.

• Cerebellum: Coordinates movement, balance, and motor learning; essential for smooth and precise motor function.

Brainstem Functions

• The brainstem controls essential life-sustaining functions like breathing, heart rate, and relaying messages between the brain and the spinal cord. It includes the midbrain, pons, and medulla oblongata.

Cranial Nerves

• Control various sensory and motor functions in the head and neck; there are 12 pairs of cranial nerves, each serving specific functions, contributing to vision, taste, smell, and facial sensations, among others. Damage to these nerves can lead to significant impairments.

Cognitive Functions of the Brain

Cerebral Cortex

• Divided into four main lobes:

  • Frontal Lobe: Critical for executive functions, voluntary movement, personality, and complex decision-making.

  • Parietal Lobe: Processes somatosensory information, allowing for spatial awareness and navigation.

  • Temporal Lobe: Integral to auditory processing, comprehension of language, and memory storage.

  • Occipital Lobe: Primarily focused on visual processing; interprets visual stimuli and information.

Structure of the Cerebral Cortex

• Highly folded with a rich layer of grey matter, optimizing cognitive functions. It contains six layers, each responsible for particular functions, including molecular, external granular, pyramidal, and multiform layers that contribute to complex information processing.

Hemispheric Communication

• The left and right hemispheres are connected by the Corpus Callosum, facilitating communication between them. Each hemisphere has specialized functions, with the left hemisphere associated with language and logical reasoning, while the right hemisphere is related to spatial awareness and emotional responses.

Neuroplasticity

• Definition: The brain's ability to reorganize itself by forming new neural connections in response to learning, experience, or injury.

• Mechanisms of Neuroplasticity:

  • Synaptic Plasticity: Involves Long-Term Potentiation (LTP), which strengthens synaptic connections, and Long-Term Depression (LTD), which weakens them.

  • Neurogenesis: The process of creating new neurons, predominantly found in the hippocampus.

  • Cortical Remapping: The brain's capability to adapt, allowing other areas to take on functions after injury or loss.

Learning and Memory

• Neuroplasticity is fundamental to learning, memory formation, and recovery from brain injuries, enhancing cognitive capabilities. Hebb's Rule posits that “neurons that fire together wire together,” reflecting the associative nature of learning.

Factors Influencing Neuroplasticity

• Various factors can enhance neuroplasticity, such as:

  • Physical exercise, which increases blood flow and promotes neuronal growth.

  • Cognitive training, engaging in complex mental tasks can strengthen neural connections.

  • Mindfulness practices, which have been linked to structural changes in brain regions associated with attention and emotion regulation.

Final Review

• The brain consists of three main regions: hindbrain, midbrain, and forebrain, all organized into distinct lobes, each serving unique functions. Neuroplasticity plays a vital role in adaption, memory formation, and recovery of brain functions after injuries.