Test 2 Flashcards
Sensory transduction
The translation of sensory input into electrical signals the brain can understand
Labeled lines
Each nerve input to the brain reports only a particular type of information
Ex) vibration, pressure, temp etc
Receptive fields
A region where a stimulus will change the neuron’s firing rate
Size of receptive field
Large receptive field= less sensitivity
Small receptive field = more sensitivity
Rate coding
Firing of AP recorded as #AP/sec
Codes intensity
Range fractionation
Divides multiple receptors of a certain sensory neuron based on intensity
Has min and max firing rate
Phasic receptors
Decrease frequency of AP after intital stimulation
Adaptation
Loss of receptor sensitivity as stimulation is maintained
Tonic receptors
Show no decline or slow decline in AP frequency (I.e. Pain, proprioceptor)
Center Modulation of Sensory Information
The process in which higher brain centers, such as cortex and thalamus, suppress some sources of sensory information and amplify others
-“top-down” influences
Polymodal neurons
A neuron where information from more than one sensory system converges
Synesthesia
A condition in which stimulation in one sensory pathway evokes an involuntary experience in a second sensory pathway
Graphemes color synesthesia
See colors associated with numbers
*convergence of different sensory systems allows the systems to interact
Humunculus
The size of each body part reflects the proportion of S1 devoted to that part
Motor system
Biggest areas: hands, lips and tongue
Sensory system
Biggest areas: hand, thumb, lips
Nociceptors
A receptor that responds to stimuli that produce tissue damage or pose the threat of damage
Pain receptor
Delta fibers
Large diameter, myelinated and thus fast conducting axon
- transmits pain info
- phasic receptors
C fibers
A small, unmyelinated and thus conduct pain info slowly and adapts slowly
-tonic receptor
Substance P
A peptide transmitter that selectively boosts pain signals and remodels pain pathway neurons
Cingulate Cortex
Region of medial cerebral cortex that lies dorsal to the corpus callosum
-integrates pain info
Analgesic drugs
Opiate drugs bind to specific receptors in the brain that decrease pain
TENS
Mild electrical stimulation to nerves around the injury sites to relieve pain
Placebo effect
Relief of a symptom that results from a treatment known to be ineffective
Acupuncture
Insertion of needles at designated points on the skin to alleviate pain or neurological malfunction
Extreme stress
Can produce significant analgesia
Proprioception
Body sense; info about position and movement of the body
-tonic receptors
Motoneuron
A neuron that transmits neural messages to muscles or glands
Neuromuscular junction
Region where the motoneuron terminal meets the adjoining muscle fiber to transmit its message
Pyramidal (corticospinal) system
Forms pyramidal tract
From frontal cortex (pre-central gyrus) to brain stem to spinal cord
Primary motor cortex (M1)
Executive region for the initiation of movement
Pre Central gyrus
The strip of frontal cortex that is crucial for motor control
M1 neurons
Most encode movements in a particular direction rather than a specific muscle contraction
SMA (supplementary motor cortex)
Premotor cortex
Code behaviors involving multiple muscles rather than specific muscle movements
Extrapyramidal System
Basal ganglia and cerebellum
-adjust the commands received from the other parts of the motor control system
Ataxia
Loss if voluntary muscle control and balance
-damage to extrapyramidal system (cerebellum)
Diseases of Basal Ganglia
Parkinson’s disease
Huntington’s disease
Parkinson’s disease
- hypokinesia (less mov’t)
- lack of spontaneous movements
- bradykinesia-slowing of movement
- rigidity and postural instability
- tremor when stationary (resting tremor)
Huntington’s disease
Hyperkinesia (more mov’t)
- excess spontaneous movement
- writing, dance like movements (chorea)
- also affects mood and cognition
Sound waves
Changes in air pressure
Compression
Higher pressure
Rarefaction
Lower pressure
Amplitude (Intensity) = Loudness
Measured as sound pressure # of molecules measured in dB
Frequency = Pitch
The number of cycles per second in a soundwave measured in hertz
-speed of compression/rarefaction.
Timbre = Complexity
Complexity of a sound wave
Pure tone
Tone with only a single frequency of vibration
-rare in real world
Fundamental frequency
Basic
Predominant frequency of an auditory tone
Harmonies
Multiples of the fundamental
Transduction of sound
1. Cochlea
Cochlea: fluid filled, cooked chambers where mechanical vibrations of the middle ear are transfixed into electrical signals
2.
Traveling wave causes basilar (base) membrane to move
3.
When the basilar membrane vibrates, Inner Hair Cells (IHC) bounce up against the tectorial (roof) membrane and stimulates stereocilia
4.
Vibration pops be “tip links” allowing k+ and ca2+ to rich into the stereocilia and depolarize the cell
5.
Depolarization initiates AP on the spiral ganglion cells, whose axons form the vestibulocochlear nerve
Inner hair cells
- bottom up = afferent
- detect pitch and intensity
- 95% of al fibers provide info to brain
- top down = efferent
- control responsiveness of IHC