Neural Signal Detectives

Biological Breakdown Point:

Provisional Diagnosis:

PATIENT D Beatrice H., Age 73 • Retired Librarian

Presenting: Cognitive & Memory Degradation

Medical Chart: Family reports worsening short-term memory loss (repeatedly asking the same question within minutes), becoming disoriented in her own neighborhood, and misplacing objects in unusual locations. Motor reflexes and physical strength remain normal, but brain scans reveal abnormal protein tangles and plaque deposits in the hippocampus.

Key Symptoms Isolated (List 2):

Biological Breakdown Point:

Provisional Diagnosis:

Part 3: Clinical Reasoning (CER Challenge)

Scientific Explanation

Medical Board Scenario: A pharmaceutical startup claims: "We developed an exercise supplement that strengthens arm and leg muscles by 50%. This drug will cure patients with ALS (Patient C) and MS (Patient B)!"

As the lead medical detective, write a claim refuting this statement. Explain why strengthening muscles does not solve the underlying neural miscommunication:

Claim:

Evidence:

Reasoning:

PLTW Medical Detectives • Activity 2.3 Diagnostic Record

Medical Director Approval:

Cellular Failure: Progressive death of dopamine-producing neurons in the substantia nigra. Lack of neurotransmitter causes motor circuits to fail to initiate smooth muscle signals.

PATIENT B: Elena R. Multiple Sclerosis (MS)

Key Symptoms: Episodes of optic neuritis (blurred vision), extremity numbness/tingling, spinal electric sensation (Lhermitte's sign).

Cellular Failure: Autoimmune attack against the myelin sheath in the CNS. Damaged insulation causes signals to leak and slow down along both sensory and motor axons.

PATIENT C: David K. ALS (Lou Gehrig's Disease)

Key Symptoms: Hand weakness, tripping, muscle twitches (fasciculations), slurred speech; intact touch and memory.

Cellular Failure: Progressive degeneration of motor neurons in brain and spinal cord. Sensory neurons remain healthy, but motor cables to voluntary skeletal muscles wither and die.

PATIENT D: Beatrice H. Alzheimer's Disease

Key Symptoms: Progressive short-term memory loss, geographic disorientation, confusion; normal motor strength.

Cellular Failure: Abnormal accumulation of beta-amyloid plaques and neurofibrillary tau tangles in the hippocampus and cerebral cortex, destroying synaptic transmission between memory neurons.

PLTW Medical Detectives • Activity 2.3 Teacher Instructional Guide PAGE 1 OF 2 — SEE FACILITATION & DIFFERENTIATION

Instructional Facilitation & Differentiation

PLTW ACTIVITY 2.3 SUPPORT

Part 3 CER Exemplar (How to Evaluate Student Explanations)

Claim: Muscle-strengthening supplements will NOT cure patients with ALS or Multiple Sclerosis.

Evidence: In ALS (Patient C), motor nerves are degenerating; in MS (Patient B), the protective myelin insulation is destroyed. Both patients have healthy muscle tissue at the cellular level.

Reasoning: Muscles are only effector organs that require electrical impulses from the nervous system to contract. If the nerve cable is dead or the myelin sheath is stripped, no command signal can ever reach the muscle, regardless of how strong the muscle tissue itself is.

Common 7th Grade Misconceptions & Correction Prompts

Misconception: "If someone can't move their arm, their arm is paralyzed and can't feel touch." Teacher Re-route: Have students separate sensory vs. motor circuits: "Sensory nerves carry signals IN to the spinal cord; motor nerves carry commands OUT. In ALS, only the outgoing motor wires are dying!"

Misconception: "Nerves touch muscles directly like physical strings or pulleys." Teacher Re-route: Review the neuromuscular junction (synapse): "There is a chemical gap! If neurotransmitters aren't released or receptors are blocked, the physical connection means nothing."

Misconception: "Myelin is just skin or fat that doesn't do anything active." Teacher Re-route: Use the charging cable analogy: "What happens when you strip the rubber coating off your phone charger wire? The electricity leaks and sparks; your phone won't charge."

Tiered Differentiation Strategies

Scaffolding & IEP / ELL Support

• Provide the 4 pathology vocabulary strips (Demyelination, Dopamine Loss, Motor Neuron Death, Plaque) for matching.
• Use paired reading: Partner 1 reads the symptoms, Partner 2 points to the diagram location.
• Sentence frame for CER: "The pill will not work because the disease damages the ________, which prevents signals from reaching the ________."

Extensions & Fast Finishers

• Biomedical Engineering Link: Have students propose how a "deep brain stimulator" (electrical pacemaker) could treat Parkinson's tremors.
• Autoimmune Investigation: Research why the body's immune T-cells mistakenly attack self-myelin in Multiple Sclerosis.
• Create a 30-second patient consultation script explaining their diagnosis in empathetic, 7th-grade language.

Exit Ticket Quick Rubric (3 Points Total)

1 Point: Identification Correctly links symptoms to the affected neurological part (Myelin, Dopamine, or Motor Neuron).

1 Point: Cellular Mechanism Explains HOW the message is physically altered (slowed down, lost, or blocked).

1 Point: Diagnostic Reasoning Articulates that sensory and motor pathways function via separate specialized nerve fibers.

PLTW Medical Detectives • Activity 2.3 Master Guide CONFIDENTIAL TEACHER RESOURCE