Neuroscience Fundamentals - Brain Structures & Function Flashcards

Question 1

Frontal Lobe

Accepted Answer

Located at the anterior portion of the cerebrum. Responsible for high-level executive functions (decision-making, planning, reasoning), voluntary motor control (primary motor cortex), and speech production (**Broca's area**).

Question 2

Temporal Lobe

Accepted Answer

Located laterally beneath the parietal and frontal lobes. Functions in processing auditory information, language comprehension (**Wernicke's area**), memory formation (via the adjacent **hippocampus**), and emotional processing.

Question 3

Parietal Lobe

Accepted Answer

Located superior to the temporal lobe and posterior to the frontal lobe. Contains the primary somatosensory cortex (postcentral gyrus) responsible for processing sensory input such as touch, temperature, spatial orientation, and proprioception.

Question 4

Occipital Lobe

Accepted Answer

Located at the posterior region of the cerebral cortex. Serves as the primary center for visual processing, interpreting visual stimuli such as shape, color, movement, and spatial relationships.

Question 5

Cerebellum

Accepted Answer

Structure located inferior to the occipital lobe and posterior to the brainstem. Crucial for motor coordination, fine motor control, timing, posture, balance, and procedural motor learning.

Question 6

Brainstem (Midbrain, Pons, Medulla)

Accepted Answer

Connects the cerebrum to the spinal cord. Controls essential autonomic vital functions including heart rate, respiration, blood pressure, and swallowing, while serving as a conduit for ascending and descending neural tracts.

Question 7

Limbic System Key Structures

Accepted Answer

A circuit governing emotion, memory, and drive. Major structures include:
- **Amygdala**: Emotional processing, fear conditioning.
- **Hippocampus**: Consolidation of explicit/declarative memory.
- **Thalamus**: Sensory relay station.
- **Hypothalamus**: Homeostatic control and endocrine regulation.

Question 8

Neuron Morphology: Soma, Dendrites, Axon

Accepted Answer

- **Soma (Cell Body)**: Contains the nucleus and organelle machinery for protein synthesis.
- **Dendrites**: Branching extensions that receive input signals from other neurons.
- **Axon**: Single long process that conducts action potentials away from the soma toward target cells.

Question 9

Resting Membrane Potential

Accepted Answer

The electrical potential difference across a non-excited neuron's membrane, typically around $-70	ext{ mV}$. Maintained primarily by leak $	ext{K}^+$ channels and the $	ext{Na}^+/	ext{K}^+$ ATPase pump ($3	ext{ Na}^+$ pumped out, $2	ext{ K}^+$ pumped in).

Question 10

Phases of the Action Potential

Accepted Answer

1. **Depolarization**: Threshold reached (approx. $-55	ext{ mV}$), voltage-gated $	ext{Na}^+$ channels open $ightarrow$ rapid $	ext{Na}^+$ influx.
2. **Repolarization**: $	ext{Na}^+$ channels inactivate; voltage-gated $	ext{K}^+$ channels open $ightarrow 	ext{K}^+$ efflux.
3. **Hyperpolarization**: Slow closure of $	ext{K}^+$ channels causes membrane potential to briefly drop below $-70	ext{ mV}$.

Question 11

Absolute vs. Relative Refractory Period

Accepted Answer

- **Absolute Refractory Period**: Voltage-gated $	ext{Na}^+$ channels are inactivated; no stimulus can fire a second action potential.
- **Relative Refractory Period**: $	ext{Na}^+$ channels are reset, but voltage-gated $	ext{K}^+$ channels are still open; an above-threshold stimulus is required to trigger an action potential.

Question 12

Saltatory Conduction

Accepted Answer

The rapid mechanism of action potential propagation along a **myelinated axon**, where the impulse jumps from one **Node of Ranvier** (unmyelinated gap) to the next, dramatically increasing signal velocity.

Question 13

Synaptic Transmission Steps

Accepted Answer

1. Action potential invades the presynaptic terminal.
2. Depolarization opens voltage-gated $	ext{Ca}^{2+}$ channels.
3. $	ext{Ca}^{2+}$ influx drives synaptic vesicle exocytosis, releasing neurotransmitters into the cleft.
4. Neurotransmitters bind postsynaptic receptors, inducing graded potentials.

Question 14

Excitatory vs. Inhibitory Postsynaptic Potentials

Accepted Answer

- **EPSP**: Membrane depolarization (e.g., opening ligand-gated $	ext{Na}^+$ channels), bringing potential closer to threshold.
- **IPSP**: Membrane hyperpolarization (e.g., opening ligand-gated $	ext{Cl}^-$ or $	ext{K}^+$ channels), moving potential further from threshold.

Question 15

Major Neurotransmitters & Primary Roles

Accepted Answer

- **Glutamate**: Main excitatory NT in CNS.
- **GABA**: Main inhibitory NT in brain.
- **Acetylcholine**: Neuromuscular junction signaling, parasympathetic targets, memory.
- **Dopamine**: Reward, motivation, voluntary movement.
- **Serotonin**: Mood, sleep, digestion regulation.

Question 16

Dorsal Column-Medial Lemniscal (DCML) Pathway

Accepted Answer

Ascending sensory pathway mediating **fine touch, 2-point discrimination, vibration, and proprioception**. First-order neurons ascend ipsilaterally in the spinal cord, decussate in the **medulla oblongata**, and project via the thalamus to the primary somatosensory cortex.

Question 17

Spinothalamic Pathway (Anterolateral System)

Accepted Answer

Ascending sensory pathway mediating **pain, temperature, and crude touch**. First-order neurons enter the spinal cord and decussate **immediately** at that spinal cord segment before ascending contralateral to the thalamus and somatosensory cortex.

Question 18

Corticospinal Tract (Pyramidal Tract)

Accepted Answer

Major descending motor pathway responsible for voluntary movement of limbs and trunk. Originates in the primary motor cortex, passes through the internal capsule, and decussates (~90%) at the **pyramidal decussation** in the lower medulla.

Question 19

Upper Motor Neuron (UMN) vs. Lower Motor Neuron (LMN) Lesions

Accepted Answer

- **UMN Lesion**: Damage in CNS tracts $\rightarrow$ Spastic paralysis, hyperreflexia, hypertonia, positive Babinski sign.
- **LMN Lesion**: Damage in peripheral nerves/anterior horn $\rightarrow$ Flaccid paralysis, hyporeflexia/areflexia, muscle atrophy, fasciculations.

Question 20

Autonomic Nervous System Divisions

Accepted Answer

- **Sympathetic**: Thoracolumbar origin; 'fight-or-flight'; short preganglionic and long postganglionic fibers (uses Norepinephrine at target).
- **Parasympathetic**: Craniosacral origin; 'rest-and-digest'; long preganglionic and short postganglionic fibers (uses Acetylcholine at target).

Neuroscience Fundamentals - Brain Structures & Function

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