Biological Bases of Behaviour in Dentistry

Sensory Neurons

Transmit information from sensory receptors to the brain (afferent).

Motor Neurons

Transmit commands from the brain to the muscles and glands of the body (efferent).

Interneurons

Interconnect neurons, most common type of neuron.

Neurotransmitters

Chemicals that transmit information from one cell to another.

Presynaptic Cell

The cell that releases neurotransmitters in response to an action potential.

Synaptic Cleft

The space between the presynaptic and postsynaptic cells where neurotransmitters diffuse.

Postsynaptic Receptors

Receptors that bind neurotransmitters and produce a graded potential in the next cell.

Vesicles

Small membrane-bound sacs in the presynaptic cell that store neurotransmitters.

Autonomic nervous system (ANS)

The ANS has two divisions: Sympathetic (Emergency system, typically activated in face of a threat e.g., fight or flight) and Parasympathetic (Vegetative functions e.g., digestion, 'business as normal').

Sympathetic nervous system

Emergency system, typically activated in face of a threat (e.g., fight or flight).

Parasympathetic nervous system

Vegetative functions (e.g., digestion), 'business as normal'.

Cranial nerves

The 12 pairs of cranial nerves are arranged in groups along the longitudinal axis of the brainstem.

Trigeminal Nerve (Cranial Nerve V)

Key role in pain perception (e.g., dental pain, temporomandibular disorders), motor control of mastication muscles, basis for local anesthesia targeting.

Branches of the Trigeminal Nerve

Ophthalmic, Maxillary, Mandibular.

Central nervous system

The Central nervous system is composed of the brain and spinal cord.

Parts of the brain

Forebrain, Midbrain, Hindbrain.

Medulla Oblongata

Extension of spinal cord that regulates heartbeat, circulation and respiration.

Cerebellum

Involved in movement, learning and sensory discrimination.

Reticular Formation

A network of neurons involved in consciousness and arousal.

Pons

Links Medulla Oblongata and Cerebellum with upper part of brainstem.

Tectum

Involved in orienting to visual and auditory stimuli.

Tegmentum

Involved in movement and arousal, plays an important role in learning to produce behaviours that minimise unpleasant (aversive) consequences and maximise pleasant (rewarding) consequences.

Hypothalamus

Helps regulate eating, sleeping, sexual activity and emotional experiences.

Thalamus

Processes incoming sensory information and transmits it to higher brain areas.

Basal Ganglia

Involved in the control of movement and also plays a part in 'automatic' responses and judgements.

Limbic System

Involved in pleasure, relief from pain, emotionally-significant learning.

Amygdala

Involved in learning and remembering emotionally significant events, and recognition of fear.

Hippocampus

Involved in the storage of new memories.

Amygdala Activation

Triggers the fight-or-flight response in patients.

Fear of Pain

Anxiety related to the anticipation of pain, needles, or loss of control during dental procedures.

Limbic System

Comprises the amygdala and prefrontal cortex, processes fear and regulates emotional responses.

Hippocampus

Stores past traumatic dental experiences, making the amygdala hyperactive during future visits.

Prefrontal Cortex

Regulates fear and can help patients reframe their dental experiences through relaxation techniques.

Cerebral Cortex

Part of the brain that provides flexible control of movement patterns and complex sensory discrimination.

Frontal Lobes

Responsible for coordinating movement, attention, planning, social skills, abstract thinking, memory, and personality.

Temporal Lobes

Important for hearing, language, object recognition, and memory.

Parietal Lobes

Involved in sensation, perception of movement, and location of objects in space.

Occipital Lobes

Specialized for vision and visual recognition.

Primary Somatosensory Cortex

Processes touch, pain, temperature, and pressure sensations, relevant for detecting oral and facial pain.

Primary Motor Cortex

Controls voluntary muscle movements, regulating chewing, biting, and swallowing.

Prefrontal Cortex Function

Involves decision-making, problem-solving, pain perception regulation, and emotional control.

Limbic System Function

Explains dental phobia and anxiety, influencing future responses to dental visits.

Temporal Lobe Function

Processes hearing and language, and stores memories relevant to past dental experiences.

Parietal Association Cortex

Integrates sensory inputs to create body awareness, allowing accurate perception of dental pain.

Cerebral Cortex

The part of the brain that governs decision-making, problem-solving, and motivation.

Prefrontal Cortex

Encourages rational thinking, allowing patients to make informed decisions about oral hygiene and treatment.

Frontal Lobes

Involved in personality, as evidenced by the case of Phineas Gage.

Somatosensory Cortex

Processes dental pain.

Amygdala

Part of the brain that is involved in the emotional response to pain, such as fear and anxiety.

Limbic System

Involved in the emotional response to pain.

Pain Perception

The brain processes pain signals from other parts of the body, including the teeth and oral structures.

Trigeminal Nerve (CN V)

Transmits dental pain.

Motor Cortex

Controls chewing and speech.

Amygdala and Fear Responses

Stores fear responses, making past negative dental experiences increase patient anxiety.

Neurotransmitters

Chemicals like serotonin, dopamine, and endorphins that influence pain tolerance and stress levels.

Autonomic Nervous System (ANS)

Regulates involuntary bodily functions; includes sympathetic (fight-or-flight) and parasympathetic (relaxation) systems.