Unit 7: Sensation and Perception
What are the four sensory attributes? Provide examples for each.
Attributes: Modality (e.g., photoreceptors--> vision), Location (e.g., touch on finger vs. arm), Intensity (e.g., tiny spider vs. tarantula), and Duration (e.g., continuous vs. brief touch).
How would you explain the role of the basilar membrane in frequency analysis to a patient with sensorineural hearing loss?
The basilar membrane (BM) is the primary mechanism for sorting and translating sound frequencies (pitch) into neural signals sent to the brain to be interpreted for meaning.
Name the 5 flavors and their transduction mechanisms for gustation
Salty and sour (ion channels), sweet, bitter, and umami (G-protein receptors)
What clinical signs would you expect in a patient with cerebellar damage during speech tasks?
Uncoordinated speech movements (e.g., irregular articulation errors)
A patient demonstrates effortful, telegraphic speech with intact comprehension.
What lesion location would you suspect?
Broca's area, located in the inferior frontal lobe.
Name receptor types and a stimulus example for each.
Mechanoreceptors (Touch, hearing, balance, proprioception), Photoreceptors (Light, vision), Chemoreceptors (Smells, taste, chemicals), Thermoreceptors (Temperature), Nociceptors (Pain)
A patient reports muffled hearing after an ear infection.
Which part of the sound transduction pathway is most likely affected?
Middle ear
What is the clinical significance of olfactory information bypassing the thalamus?
Unlike all other forms of sensation, olfaction does not have a thalamic relay (signals do not pass through the thalamus “relay station”) and projects directly to the structures involved in emotion, memory, and behavior (e.g., amygdala and hippocampus), hence why certain smells evoke specific memories.
A patient with supplementary motor area (SMA) damage shows difficulty with complex sequential actions (i.e., speech!).
Is the primary deficit motor execution or planning? Which cerebral lobe is affected?
Motor planning/programming and frontal lobe
What diagnostic signs distinguish apraxia of speech from dysarthria during oral motor examination?
Apraxia: absence of motor weakness; motor planning difficulty of volitional movements. Automatic movements (e.g., chewing gum) are intact.
Dysarthria: motor weakness for the execution of automatic AND volitional movements.
A patient with peripheral neuropathy shows reduced ability to detect a soft touch but normal pain perception.
Which sensory modality and receptor type are likely affected?
Sensory modality: Mechanoreceptor and touch/pressure is affected
A patient reports dizziness when turning their head quickly.
Which vestibular structure is most likely involved?
Semicircular canals: Detect and transduce head rotation and angular acceleration.
- With sudden rotation of the head, the endolymph fluid within the semicircular canal is displaced.
What cranial nerves (Roman numeral, name, and sensory function) are important for olfaction and gustation?
CN I: Olfactory (Smell), CN V: Trigeminal (Facial sensation), CN VII: Facial (Taste at the anterior 2/3 of the tongue), CN IX: Glossopharyngeal (Taste at the posterior 1/3 of the tongue), CN X: Vagus (Taste at the epiglottis and pharyngeal cavity)
A patient demonstrates ideomotor apraxia.
Which cortical area is likely involved?
Ideomotor apraxia (difficulty performing learned movements on command).
- Damage is to the premotor area in the left hemisphere frontal lobe.
Describe the dual-stream model (dorsal and ventral pathways)
Dorsal: repetition tasks, mapping sound to movement.
Ventral: semantic and syntactic processing (language comprehension), mapping sound to meaning.
A patient with a cortical lesion can detect stimuli but cannot interpret them meaningfully. Which process, sensation or perception, is primarily disrupted?
Perception
How does phase-locking in auditory nerve fibers influence speech perception in low-frequency sounds?
Phase-locking can be used to perceive frequency.
Auditory nerve fibers transmit information on the frequency, intensity, and timing of auditory inputs simultaneously through one sensory signal.
How would you explain the role of taste and smell in initiating swallowing?
Swallowing is sensorimotor behavior, meaning that motor coordination of food textures requires sensory feedback to work properly (Triggering of the swallow reflex relies on sensory input/feedback).
How does understanding the basal ganglia’s function help you explain hypokinetic dysarthria to a caregiver?
BG works within a complex feedback loop (receiving and processing signals) and uses direct and indirect pathways to start or stop movement.
What therapy approach capitalizes on the principles of neuroplasticity for a patient recovering from aphasia post-stroke?
Constraint-induced language therapy (CILT)
A patient reports difficulty localizing touch on their forearm.
Which sensory attribute is impaired, and what does this suggest about receptive field size and density?
Sensory attribute: Location
Receptive field size is large and low sensitivity.
A patient with a cerebellar lesion demonstrates impaired vestibulo-ocular response (VOR) and poor ability to maintain gaze.
How does this finding help localize the lesion within the vestibular pathways?
VOR senses head rotation and motion to perform compensatory responses of the extraocular muscles to maintain gaze in the correct orientation and position for a visual target.
- Vestibular nuclei neurons that project to cranial nerves innervating extraocular muscles of eye
A patient with a tracheostomy reports food tasting bland and decreased appetite.
What anatomical change explains this complaint?
What should the SLP keep in mind when counseling?
Procedures like tracheostomy may disrupt typical airflow through the oral and nasal passages, reducing taste and smell, which impacts appetite and overall quality of life for patients with brain/spinal cord injuries.
Distinguish between open-loop vs closed-loop motor control and provide examples.
Open-loop: movement is pre-planned and executed without real-time feedback. Relies on previous experiences. (e.g., Throwing a dart).
Closed-loop: Movement is continuously monitored and adjusted using sensory feedback. (e.g., Adjusting grip strength while holding a fragile object).
How does damage to the periaqueductal gray (PAG) affect vocalization?
PAG is involved in generating motor commands for innate vocalization and regulating learned vocalizations.
Damage can lead to mutism.