Neuron Structure, Brain Lobes, Limbic System & Nervous System
Neuron Structure and Function
Dendrites: Extensions from the neuron cell body that take information to the cell body.
Nucleus: Part of the neuron that contains chromosomes (genetic material).
Cell Body: Also called the soma. The part of the cell that contains the nucleus.
Myelin: Fatty substance that surrounds some axons. Speeds up conduction velocity of action potentials.
Node of Ranvier: Gaps in the myelination of axons.
Axon: The part of the neuron that takes information away from the cell body.
Synaptic Terminal: The end of the axon containing vesicles with neurotransmitters.
Brain Lobes and Their Functions
Temporal Lobe: For auditory processing, receptive language, and memory functions.
Frontal Lobe: Reasoning, planning, parts of speech, movement, emotions, and problem-solving. Coordinating movement (planning & predicting consequences of behaviors). Motor behavior, expressive language, and directed attention.
Parietal Lobe: Links senses with motor abilities and the creation of the experience & sense of our body in space. Associated with movement, orientation, recognition, and perception of stimuli.
Occipital Lobe: Includes the areas for visual processing.
Cerebellum: Associated with regulation & coordination of movement, posture, & balance. Thought & action. Motor planning, cognition, involuntary functions, and problem-solving.
Brain Stem: Transition between the spinal cord and the brain. Regulates vital body functions: breathing, heart rate, and other automatic functions.
The Limbic System: Emotions, Memory, and Learning
The Triune Brain = limbic system considered the paleomammalian brain.
Amygdala: Emotions. Involved in memory, emotion, anger, & fear.
Hippocampus: Learning/Memory. Converting short-term memory to more permanent memory.
Thalamus: Gateway for sensory info. Touch, taste, sight, sound. NOT SMELL.
Hypothalamus: Functions including homeostasis, emotion, thirst, hunger, circadian rhythms, sexual behaviors, & control of the autonomic nervous system. Regulating autonomic functions including biological rhythms and stress.
Anterior Insula: Monitoring internal body experiences.
Olfactory Bulb: Smell.
Pituitary Gland: Regulates hormones.
Cingulate Gyrus: Monitoring conflicts and regulating emotions.
Orbitofrontal Cortex: Part of the pre-frontal cortex. Sensory integration, the modulation of autonomic reactions, and participation in learning, prediction, and decision making for emotional and reward-related behaviors.
Broca’s Area: Speech production.
The Vagus Nerve and Neurophysiological States
Vagus Nerve: Branches into 2 major pathways – each responsible for a distinct neurophysiological state.
Ventral: Responds to cues of safety and supports a sense of centeredness and readiness for social engagement.
Dorsal: Responds to cues of life-threat causing us to shut down, become numb, and disconnect from others. A client who dissociates has found refuge in a dorsal vagal state.
The Autonomic Nervous System (ANS)
The body’s rapid-response survival system is orchestrated by our AUTONOMIC NERVOUS SYSTEM (ANS):
Sympathetic: Mobilizes us to defend against danger via the fight-or-flight response.
Parasympathetic: Less understood branch. Viewed as a unitary system that helps us lower our defenses and regain a state of calm. Made up of the Vagus Nerve.
Neurons and Glia
Another name of a nerve cell: NEURON – 100 billion neurons in the brain.
A neuron is the basic unit of the nervous system, and it receives, processes, and transmits signals via chemical transmission and electrical pulses.
Along with neurons, the cerebral cortex is made of 1 trillion cells known as GLIA = Supportive role in the construction, organization, and maintenance of neural systems.
Neuroception: Dr. Porges
NEUROCEPTION: DR. PORGES: Neuroception shapes the state, and the state shapes the response.
Ways ANS responds to cues of safety, danger, and life-threat from within our bodies, world, and connections to others. Different from perception, this is “detection without awareness,” a subcortical experience happening far below the realm of conscious thought.
- Gut feelings, heart-informed feelings, implicit feelings that move us along the continuum between safety and survival response.
- “Somatic signals that influence decision making and behavioral responses without explicit awareness of the provoking cues.”
The ANS assesses risk and takes action:
- From a neuroception of UNSAFETY, there is a move toward sympathetic mobilization or dorsal vagal collapse.
- From a neuroception of SAFETY, the sympathetic and dorsal vagal systems are inhibited, the ventral vagal system is in control, and the social engagement system is active and online.
Neuron Parts and Functions
The neurons have fibers called axons covered with myelin, an insulator that enhances the efficiency of communication.
The white matter of the brain is because myelin is white; the unmyelinated gray matter consists of primarily of neural cell bodies.
Dendrites are elaborate branches which form synaptic connections with thousands of dendrites from other neurons.
- The relationships formed among dendrites organize the complex networking of the nervous system that encodes our memories, emotions, and behaviors.
Mental Operating System and Therapy
Salience Network: Therapy has to be emotionally relevant, feel “right” and meaningful.
Default-mode Network: Therapy needs to provide new positive narratives to reflect on.
Executive Network: Therapy must aid present-oriented, action-directed, and productive behavior.