Group 1: Types of Human Reflexes
– Myotatic or muscle stretch reflexes provide information on nervous system integrity.
– Biceps reflex (C5, C6)
– Brachioradialis reflex (C5, C6, C7)
– Extensor digitorum reflex (C6, C7)
– Triceps reflex (C6, C7, C8)
– Patellar reflex or knee-jerk reflex (L2, L3, L4)
– Tendon reflex involves muscle contraction in response to striking its tendon.
– Reflexes can be graded on a scale from 0 to 4 to assess nervous system health.
– 2+ is considered normal.
– Some individuals are hypo-reflexive (1+) or hyper-reflexive (3+).
– Different grading systems exist, such as from -4 (absent) to +4 (clonus).
Group 2: Reflex Modulation
– Reflexes can be modified to match behavioral requirements in vertebrates and invertebrates.
– Stretch reflex can lead to muscle contraction or resistance reflex.
– Mechanisms of reflex modulation involve sensory neuron output modulation and interneurons in the spinal cord.
– Reflex modulation prevents resistance reflexes from impeding voluntary movements.
Group 3: Other Reflex Concepts
– Breathing can be both involuntary and voluntary.
– Reflex reversal: Same spinal reflex pathway can cause limb flexion while standing and extension while walking.
– Reflex arcs: Neural pathways in the nervous system that mediate reflexes.
– Many reflexes do not require conscious thought and contribute to organism survival.
– Startle reflex and feline righting reflex are examples of reflexes aiding in self-defense and survival.
– Reflexes can be short-latency with a single synapse or long-latency involving multiple synapses.
Group 4: Neural Reflexes and Control of Movement
– Study on amplitude modulation of the soleus H-reflex during walking and standing.
– Central control components of a simple stretch reflex.
– Proprioceptive sensory neurons of a locust leg receiving rhythmic presynaptic inhibition during walking.
– Role of presynaptic inputs to proprioceptive afferents in tuning sensorimotor pathways of an insect joint control network.
– Interaction between descending input and thoracic reflexes for joint coordination in cockroach.
– Central-complex control of movement in the freely walking cockroach.
– Supraspinal control of spinal reflex responses to body bending during different behaviors in lampreys.
– Neural regulation of respiration.
– Breathing coupled with voluntary action and the cortical readiness potential.
Group 5: Research and Journal Articles on Reflexes
– Various studies on amplitude modulation of reflexes during different movements.
– Research on central control components of reflexes.
– Studies on proprioceptive sensory neurons and their modulation during movement.
– Investigation of presynaptic inputs in tuning sensorimotor pathways.
– Articles on the interaction between descending input and reflexes for joint coordination.
This article about biology may be excessively human-centric. (September 2022) |
In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus.
Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs via neural pathways in the nervous system called reflex arcs. A stimulus initiates a neural signal, which is carried to a synapse. The signal is then transferred across the synapse to a motor neuron, which evokes a target response. These neural signals do not always travel to the brain, so many reflexes are an automatic response to a stimulus that does not receive or need conscious thought.
Many reflexes are fine-tuned to increase organism survival and self-defense. This is observed in reflexes such as the startle reflex, which provides an automatic response to an unexpected stimulus, and the feline righting reflex, which reorients a cat's body when falling to ensure safe landing. The simplest type of reflex, a short-latency reflex, has a single synapse, or junction, in the signaling pathway. Long-latency reflexes produce nerve signals that are transduced across multiple synapses before generating the reflex response.