Information Processing, Motor Behavior, and Cellular Basis of Motor Control

Comprehensive flashcard deck reviewing information processing stages, reaction time paradigms, Fitts' Law, neuroanatomy, glial cell function, membrane potentials, action potential kinetics, and synaptic transmission mechanisms based on the lecture material.

What are the three primary stages of information processing measured in reaction time studies?

1. Stimulus identification (perception), which includes stimulus detection and pattern recognition; 2. Response selection (decision); 3. Response programming (action).

How is reaction time (RT) defined in motor behavior, and what type of movement does it reflect?

Reaction time is defined as the speed with which an individual voluntarily responds to a stimulus. It reflects voluntary movement rather than involuntary reflexes.

Based on the provided diagram of reaction time components, what distinguishes premotor RT from motor RT?

Premotor RT is the time interval from stimulus presentation to the onset of EMG activity, whereas motor RT is the time interval from the onset of EMG activity to the beginning of physical movement.

How is total response time defined in relation to reaction time and movement time?

Total response time is the sum of reaction time and movement time ($\text{Response Time} = \text{Reaction Time} + \text{Movement Time}$).

What is the difference between simple reaction time and choice reaction time?

Simple reaction time involves only one possible signal and one possible response, whereas choice reaction time involves multiple signals where each signal designates a unique response.

What is Hick's Law, and what is its mathematical formula?

Hick's Law states that choice reaction time increases linearly with the logarithm to the base 2 of the number of stimulus-response alternatives ($N$). Its formula is $RT = a + b \times [\text{log}_2(N)]$.

How do visual and auditory stimuli compare in their effects on human reaction time?

Reaction time to auditory stimuli is faster (approximately $175\,\text{ms} - 179\,\text{ms}$) than reaction time to visual stimuli (approximately $209\,\text{ms} - 210\,\text{ms}$).

What is stimulus-response (S-R) compatibility?

S-R compatibility refers to the extent to which a stimulus and its associated response are connected in a natural or spatially aligned way; compatible setups yield faster reaction times.

What is multisensory facilitation, and when is it most effective?

Multisensory facilitation is the reduction in reaction time achieved when two or more sensory stimuli are presented together. It is most effective when the stimuli are presented simultaneously.

According to the Yerkes-Dodson Law shown in the figure, how does arousal level affect performance on simple versus complex tasks?

For complex tasks, performance follows an inverted U-curve with optimal performance at moderate arousal levels. For simple tasks, performance increases with arousal and remains strong even at high arousal levels.

At what altitude threshold does choice reaction time begin to increase significantly according to Dykiert et al. (2010)?

Choice reaction time increases significantly at high altitudes above $4000\,\text{m}$ to $4500\,\text{m}$.

How do sports experience and skill level affect simple reaction time versus choice (Go/Nogo) reaction time in athletes?

Simple reaction time does not differ significantly based on sports experience or skill level. However, choice (Go/Nogo) reaction time is significantly faster in trained athletes and individuals with higher skill levels.

What is the mathematical formulation of Fitts' Law, and what do its variables represent?

Fitts' Law is expressed as MT = a + b \times \text{log}_2\text{(\frac{2A}{W})}, where $MT$ is movement time, $A$ is movement amplitude (distance), $W$ is target width, and \text{log}_2\text{(\frac{2A}{W})} is the Index of Difficulty ($ID$).

Under Fitts' Law, what happens to the Index of Difficulty ($ID$) if both movement amplitude ($A$) and target width ($W$) are doubled simultaneously?

The Index of Difficulty ($ID$) remains unchanged because $ID$ depends on the ratio $\frac{2A}{W}$, keeping movement time ($MT$) constant.

What are the three basic cell types found in the nervous system?

Neurons (nerve cells), Glia (supporting cells), and Stem cells (immature, undifferentiated cells).

Based on the provided diagram, what are the three basic structural types of neurons and their functional examples?

1. Bipolar neurons (e.g., interneurons); 2. Unipolar neurons (e.g., sensory neurons); 3. Multipolar neurons (e.g., motoneurons).

How many glial cells exist relative to neurons in the human brain, and what are their primary roles?

Glial cells outnumber neurons roughly 10 to 1 (approximately 1 trillion glia versus 100 billion neurons). They provide structural support, cellular communication, and nutritive functions.

What are the main physiological functions of astrocytes?

Astrocytes act as scavengers to remove $K^+$ and neurotransmitters, convey signals to dilate blood vessels for nutrient delivery (glucose and oxygen), maintain the blood-brain barrier, and assist in CNS development.

How do oligodendrocytes and Schwann cells differ in location and function?

Oligodendrocytes provide myelin sheaths for axons in the Central Nervous System (CNS). Schwann cells myelinate neurons in the Peripheral Nervous System (PNS) and aid in axonal regrowth.

What clinical conditions are associated with demyelination in the CNS versus the PNS?

Central Nervous System (CNS) demyelination leads to Multiple Sclerosis (MS), while Peripheral Nervous System (PNS) demyelination leads to peripheral neuropathies such as Guillain-Barr) syndrome.

According to the image, what are the primary types of gated ion channels found on neuronal membranes?

Ligand-gated channels (opened by neurotransmitters), Mechanically-gated / modality-gated channels (opened by mechanical pressure/sensory stimuli), Voltage-gated channels (opened by membrane potential changes), and Always open (leak) channels.

What ionic concentrations and membrane properties establish the typical resting membrane potential of $-70\,\text{mV}$ in a neuron?

Higher concentration of $Na^+$ in extracellular fluid (ECF), higher concentration of $K^+$ and impermeable anions in intracellular fluid (ICF), selective permeability to $K^+$ diffusion down its concentration gradient, and active maintenance by the $Na^+/K^+$ pump.

Referring to the action potential graph, what ion movements drive the depolarization and repolarization phases?

Depolarization is driven by the opening of voltage-gated $Na^+$ channels and rapid $Na^+$ influx. Repolarization is driven by the closure of voltage-gated $Na^+$ channels and opening of voltage-gated $K^+$ channels causing $K^+$ efflux.

What causes the absolute refractory period versus the relative refractory period during an action potential?

The absolute refractory period is caused by the inactivation of voltage-gated $Na^+$ channels. The relative refractory period corresponds to elevated $K^+$ permeability (hyperpolarization), requiring a stronger-than-normal depolarizing stimulus to trigger an action potential.

What is saltatory conduction, and how does myelination affect nerve conduction velocity?

Saltatory conduction is the rapid propagation of an action potential jumping from node to node at the Nodes of Ranvier along a myelinated axon. Myelinated fibers conduct signals at approximately $100\,\text{m/s}$, compared to $0.5\,\text{m/s} - 2\,\text{m/s}$ in unmyelinated fibers.

What sequence of cellular events occurs during chemical synaptic transmission upon the arrival of an action potential at the presynaptic terminal?

1. Action potential depolarizes the presynaptic axon terminal; 2. Voltage-gated $Ca^{2+}$ channels open, causing $Ca^{2+}$ influx; 3. $Ca^{2+}$ entry triggers exocytosis of synaptic vesicles containing neurotransmitters; 4. Neurotransmitter diffuses across the synaptic cleft and binds to postsynaptic receptors.

What distinguishes an Excitatory Postsynaptic Potential (EPSP) from an Inhibitory Postsynaptic Potential (IPSP)?

An EPSP causes local membrane depolarization via an influx of positive ions ($Na^+$ or $Ca^{2+}$), moving membrane potential closer to threshold. An IPSP causes local hyperpolarization via $Cl^-$ influx or $K^+$ efflux, moving membrane potential farther below threshold.

What is the difference between spatial summation and temporal summation of postsynaptic potentials?

Spatial summation is the combining of postsynaptic potentials generated simultaneously from multiple different presynaptic inputs. Temporal summation is the combining of postsynaptic potentials generated in rapid succession from repeated stimuli at a single presynaptic input.

What is the cellular mechanism of presynaptic inhibition at an axoaxonic synapse?

A modulatory neuron fires at an axoaxonic synapse, reducing the opening of voltage-gated $Ca^{2+}$ channels in the presynaptic terminal. Reduced $Ca^{2+}$ influx decreases neurotransmitter release, resulting in a smaller EPSP on the postsynaptic membrane.

How do Botulinum toxin (Botox) and local anesthetics (e.g., lidocaine, cocaine) affect neural function?

Botulinum toxin blocks presynaptic $Ca^{2+}$ channels, inhibiting acetylcholine release at the neuromuscular junction. Local anesthetics block voltage-gated $Na^+$ channels, preventing action potential generation in small-diameter pain fibers.

How do cocaine and nicotine alter neurotransmitter action in the brain?

Cocaine blocks dopamine transporters/reuptake, leading to accumulated dopamine and increased pleasure center stimulation. Nicotine acts via presynaptic facilitation to increase dopamine release.