PSYC 125 Week 4: Sensorimotor Functioning

precentral gyrus

primary motor cortex

* anterior of central sulcus
* located in frontal lobe

postcentral gyrus

primary sensory cortex

* posterior to central sulcus
* located in parietal lobe

somatosensory processing

* external
* internal
* receptors

external processing

* touch
* pain
* heat

internal processing

* body position
* fever

receptor types

* mechanical
* chemical
* thermo
* nocioceptors
* proprioceptors

mechanical

physically moved

chemical

respond to chemicals

thermoreceptors

respond to temperature

nocioceptors

pain

proprioceptors

body position

gustatory (taste) system

info sent from tongue → thalamus → multiple brain regions

ageusia

absence of taste

dysgeusia

reduced taste; bland

phantogeusia

tasting things that aren’t there

olfaction system

* info sent from olfactory bulb → limbic system → frontal cortex

anosmia

absence of smell

dysosmia

impaired smell

phantosmia

* smell something that is not there


* common in epilepsy
* bad smells

what do smell receptors go through?

penetrate through bone

what happens to smell after head injury?

sense of smell damaged

what is needed for chemical senses to breakdown molecules for brain processing?

moisture

homunculus

* how space is represented in brain

which body parts have the most real estate?

* mouth/lips
* hands

info sent from body to

* thalamus
* contralateral primary somatosensory cortex

astereognosis

inability to identify object by touch

finger agnosia

inability to identify fingers

paresthesia

numbness (diabetes)

phantom limb pain

feel pain in limb you lost

proprioceptive disorder

not knowing where you are in space

* falling over, not realizing arm is up

tactile extinction

patients can respond to left/right separately but not tgth bc they cancel out

motor system

info sent to body

where is the info (in motor system) sent to

* internal capsule (then decusates) → spinal cord → muscles via contralateral projections

supplementary motor area

* motor sequencing, timing, initiation
* INTERNAL cues

premotor area

* motor sequencing, timing, initiation
* EXTERNAL cues

cingulate motor area

spontaneous movement

apraxia

absence of movement

limb-kinectic

fine motor coordination (clumsy)

ideomotor

* can’t move on demand/lots of pantomime
* idea of movement is impaired
* can do motor behavior spontaneously (limbs work)

conceptual

lost knowledge of behavior (mistaken usage)

ideational/dissociation

sequencing of motor program

* can’t rub belly and tap head at once

auditory system

* bilateral rep
* info sent from cochlea → thalamus → primary auditory cortex
* ipsilateral & contralateral inputs to cortex from each ear

visual system

info sent from retina → thalamus (LGN) → V1

visual pathway

* left visual field → right side of retina in BOTH eyes → right hemi
* right visual field → left side of retina in BOTH eyes → left hemi

optic nerve

leaves eye to carry info to brain

optic chiasm

crossover point

post-optic chiasm, what does optic nerve become?

optic tract

where does optic tract synapse at?

LGN

optic radiation

spreads out → V1

visual field deficits (hemianopias)

half of visual field is impaired

visual agnosia

can’t recognize objects/faces

achromotopsia

colorblind

disconnection syndrome

* heteromodal


* senses not combining properly
* breakdown of integration

higher order visuospatial deficits

inability to see objects from different perspective