Cortical Processing of Sensory Information

Cortical registration of sensory input

registers in S1 - area 3, 1, 2

interacts with motor cortex

highly processed in parietal lobe if it is sensory from the body (somatosensory)

visual input- occipital lobe

auditory stimuli - register in transverse temporal gyri - temporal lobe will help process sensory input

fascicle allow us to process input ad then give an output

Sensation

the registration of sensory stimuli by the nervous system

the transmission of that stimulus in the nervous system

the registration of that stimulus in the cerebral cortex

Localization and Discrimination

can localize a stimulus from area 3, 1, 2

can discriminate a stimulus based on what neurons are in the code

Perception

the processing of sensory input by the cerebral cortex

typically involves stored information from the cortex, including previous experiences

INVOLVES THE PRIMARY SENSATION +

What is the difference between sensation and perception?

sensation - HAVE THIS EXPERIENCE

perception - from previous experiences

If you lose sensation…

it is USUALLY a spinal cord, spinal nerve, or peripheral problem

If you get messed up perception…

it is USUALLY a HIGHER VENTER PROBLEM

You CANNOT have perception…

in the absence of sensation!!!

Perceptual Constancy

see familiar objects as unchanging, even when aspects of the stimulus change, such as lighting or viewing angle

Perceptual Set

tendency to perceive some stimuli but not others and to base expectations on past experience

something magicians use - focused on a stimulus and you don’t pay attention to other things

What are the unimodal neural aspects of perception?

parietal, temporal, frontal, and occipital lobes

What perception happens at the parietal lobe?

most somesthetic sensation

areas 5 and 7 (superior parietal lobule) - involved with processing of body image, body in space, organizing body in space for action

What perception happens at the temporal lobe?

most auditory sensation

transverse temporal gyri

hippocampus

What perception happens at the frontal lobe?

attention

prefrontal cortex

What perception happens at the occipital lobe?

most visual sensation

medial is more registration

What are the multimodal neural aspects of perception?

association cortex

where you pull in and integrate ALL of these modalities

inferior parietal lobule - supramarginal and angular

lateral temporal gyri

lateral occipital gyri

Where is there a large among of multimodal processing occurring?

around the posterior aspect of the lateral fissure - confluence of input from visual, auditory, and tactile modalities

What is the supramarginal gyrus?

a somatosensory association area

What is the angular gyrus?

a visual association area - also called a reading center and plays a role in arithmetic functions

Neural Networks

underlying construct of perception

no longer are there strict pathways that can be traced

rather, when faced with a stimulus, a set of neural cells are activated to help - involves system processing simultaneously of feedforward and feedback connections

it is the dynamic activity of the system that determines the outcome of computation, not inputs or initial conditions

Synesthesia

perceptual phenomenon in which stimulation of one sensory pathway automatically activates another linked pathway

What is the most common synesthesia?

color and number or letter

e.g. would always see A as red and B as blue - can happen with music and color or smell and taste

Right Hemisphere processing

uniquely specialized for spatial processing

visualization

intuitive

conceptual

think about geometry and spatial match like calculus and inference

Left Hemisphere processing

specifically designed for temporal processing

sequencing

analytical and numerical thinking about sequential math - counting, algebra, solving equations

What is the dominant hemisphere for language for MOST people?

left hemisphere - both right (95%) and left handed (33%)

What is the functional deficit when one hemisphere is damaged as in CVA?

unilateral disregard or neglect - most commonly in RIGHT hemisphere lesions

often associated with damage to superior parietal lobule

Astereognosis

inability to identify familiar objects by touch

A(dys)lexia

difficulty with reading, despite normal intelligence

angular gyrus

Dyscalculia

Agraphesthesia

can’t identify number or letter traces on back of hands with eyes closed

Prosopagnosia

inability to recognize faces, including your own

associated with damage to fusiform gyrus

Apraxia

inability to execute a motor command DESPITE the motor ability to do so - central processing disorder

dressing and construction - damage to right angular gyrus

What is difficult for kids with apraxia?

Simon says test - cannot take verbal message or visual image, process it in brain, and create motor output to do it

Proprioception

sensory input of movement

Kinesthesia

perceptual processing of movement

Aphasia

deficit in spoken or receptive language