PSY290 - Sensory and Motor Function

receiving, collecting and amplifying information from the environment

• initial phase

• sensory organs

• input

interpreting/organizing information so that we can understand and react to it

• later phase/output

• starts with receptors of specialized sensory organs

• involves key nerves in peripheral nervous system

• includes synapses with brain stem nuclei

• routed/processed by thalamus

• dedicated cortical areas

specialized receptors attached to neurons

• neurons send signals into the brain

through firing rate

• related to nature of the stimulus and duration of its application

• as it is prolonged there will be rate adaptation

with prolonged stimulation rate will increase or decrease

• common in sensory neurons

• fine touch is fast while pain is slow

the olfactory nerve

the optic nerve

vestibulocochlear nerve

• facial nerve

• glossopharyngeal nerve

• vagus nerve

various cranial and spinal nerves

pyriform cortex

orbitofrontal cortex

insula

in the temporal cortex

parietal cortex

in the occipital cortex

high and low frequency on different cells

left visual fields on right visual cortex

representation is linked to adaptive utility not size

more representation for hands than for legs

ability to form and reorganize synaptic pathways based on experiences like injury

survival (threat warning and social behavior)

• emotional tears don’t have discernable odor but influence behavior

Bipolar Receptor > Glomerulus > Olfactory nerve > Primary Olfactory Cortex (Pyriform) > Secondary Olfactory Cortex (OFC)

• detect volatile odorants

odorants activate receptors that are responsive to their shape (in relation to chemical structure

• odor compound may contain many chemicals and may then activate a compliment of receptors

• smaller olfactory bulb relative to brain volume

• fewer coding proteins

• no readily identifiable pheromones

• non coding olfactory genes

• learn some olfactory guided behaviors w/training

• don’t use sense of smell to the fullest extent

loss of sense of smell

contain gustatory cells that have receptors responding to taste molecules

mediation of sweet and bitter tastes by activity of G-protein coupled receptors

ion channels

• particularly for H+ and Na+ ions

argued to be more of a tactile sensation than a taste

capsaicinoids

they activate transient receptor potential cation channel subfamily V member1 (TRPV1) receptors

• found on tongue and other parts of the body

Scoville units

Taste cells > Bipolar neurons > Cranial nerves (7, 9, 10) > Brainstem Structures > VPM Thalamus > Primary Gustatory Cortex (Insula)

• from insula, input might also be sent to the secondary olfactory cortex

bitterness

700 to 400 nm

rods and cones that are responsive to the presence of light

function well in low light + are used in scotopic conditions

• night vision

function well in phototropic conditions and are responsible for high acuity and color vision

color blindness

Young-Helmholtz Theory

every color is a combination of three colors (and maybe activity of three different cones)

• contrasting color signals

• explains after images

different visual field region, different cortical region

graph of the perceived brightness of the same wavelength under scotopic conditions and photopic conditions

• blue looks brighter than yellow

• yellow looks brighter than blue

• subjective perception of a color remains constant under varying illumination conditions

• visual system adjusts perception of color in a scene based on perceived illumination of that scene

dress illusion

• light plays a role in perception of color

• Photoreceptors > Optic Nerve > Thalamus (Lateral Geniculate part) > Visual Cortex

• rate at which sound wave vibrate measured as cycles per second (Hz)

• intensity of sound is usually measured in dB

• allows us to distinguish tones

• perceive the pitch that is related to the greatest common divisor

• sometimes its not even present in the combination of waves

• applies to combos above 50 Hz

auditory nerve > cochlear nuclei > superior olivary nucleus > inferior colliculus > medial geniculate nucleus of the thalamus > primary auditory cortex

different frequencies , different regions of the cortex

• adaptive response to identify danger and withdraw

• insensitivity is associated with high risk for injury + early mortality

• PFC

• anterior cingulate cortex

• insula

• somatosensory cortex

• associated with individual differences

transmission of touch information modulates transmission of nociceptive information

tactile stimuli will modify the pain stimuli form the activation of the pain pathway

• occurs by unmyelinated fibers

• touch activation inhibits pain processing

ascending spinothalamic tract and modulated by descending inputs

• periaqueductal gray and rostroventral medulla

• primary motor cortex of the frontal lobe (upper motor neurons

• motor neurons axons form motor tracts, (evident in midbrain and medulla

• tracts synapse with lower motor neurons in the spinal cord which affects muscle activity

planning

sequence organization

• coordinating motor actions

• lesions would impair this ability

initiates voluntary movement (has the homunculus)

imaging movement produces similar pattern of brain activity in the frontal cortex as planning actual movement

• part of the cortex for jumping or grasping (based on 1 brain region 1 movement involving many body parts in a particular way)

1 brain region for 1 body part (popular theory)

motor and descending pathways

sensory and ascending pathways

• dorsal column medial lemniscus system

• spinocerebellar tracts

• anterolateral system

• pyramidal tracts

• extrapyramidal tracts

• lateral corticospinal tract

• anterior corticospinal tract

carries commands for movement of distal muscles (limbs + digits)

carries commands for movement of the body’s midline (proximal muscles)

• movement coordinating network

• striatum (caudate + putamen)

• globus pallidus ( internal and external)
  subthalamic nucleus

• substantia nigra

• parkinson’s disease

loss of dopaminergic neurons in the substantia nigra

dopaminergic neurons

• role in refining movement

role in posture, balance and coordination

• has a representation of every body part (similar to motor homunculus

• assist in adapting learned movements