3.2 Cerebral Cortex

most part prominent part of the mammalian brain

cerebral cortex

outer surface cerebral cortex cells

gray matter

most part prominent part of the mammalian brain

cerebral cortex

outer surface cerebral cortex cells

gray matter

axons of cerebral cortex outer surface cells located in

extending inward = white matter

how do neurons communicate to other hemisphere

• 2 axon bundles

  • Corpus callosum

  • smaller, anterior commissure

is the anterior commissure the only commissure

no, there are several others that serve as pathways across the midline to link subcortical structures

corpus callosum & anterior commissure

bundle of axons that connects the two hemispheres of the cerebral cortex

how does the cerebral cortex of primates differ from other mammals

• larger cerebral cortex

  • more folding

  • more neurons per unit volume

primates

monkeys, apes, humans

what are similar about mammal brains

same brain subareas in the same locations

what brain area has the same constant percentage across mammal species

• cerebellum

• 10 - 14%

laminae

layers of cell bodies that are parallel to the surface of the cortex and separated from each other by layers of fibers

how many laminae in cerebral cortex

6

lamina V: inner pyramidal layer

• long axons to the spinal cord and other distant areas

• thickest in motor cortex

  • greatest control of muscles

• large pyramidal cells

Lamina IV: internal granular layer

• receives axons form sensory nuclei of thalamus

• main site for incoming sensory info

  • prominent in the sensory areas (visual, auditory, somatosensory)

• absent in motor

• small cells

molecular layer, lamina I

mostly dendrites & long axons

external granular layer, lamina I

• small pyramidal cells

pyramidal cell layer, Lamina III

pyramidal cells

multiform layers, lamine VIa & VIb

spindle cells

cerebral cortex columns

groups of cells perpendicular to the surface of the cortex and to its laminae

nature of cells in specific columns

similar functions

name and locate the cerebral cortex lobes

name and locate the columns in the cerebral cortex

occipital lobe

visual information

occipital lobe location

posterior (caudal) end of the cerebral cortex

other names for occipital lobe

• striate cortex

• primary visual cortex

destruction of striate cortex causes

cortical blindness in that related part of visual field

ex: damage in Rhemi causes blindness in left visual field

how can those w eye damage induced blindness have visual dreams & scenes

• intact occipital cortex

• previous visual experience

relationship of eyes and visual cortex

eyes = stimulus

visual cortex = experience

parietal lobe

receives sensations from

• touch receptors

• muscle-stretch receptors

• joint receptors

location of parietal lobe

• between occipital lobe & central sulcus

central sulcus

deep groove in the surface of the cerebral cortex

local anesthesia

anesthetizing the scalp but leaving the brain awake

simulation of postcentral gyrus during local anesthesia result

tingling sensations on opposite side of body

postcentral gyrus aka

primary somatosensory cortex

postcentral gyrus/ somatosensory cortex

• 4 bands of cells

• parallel to central sulcus

name and identify location of interpreting sensations in the somatosensory cortex

precentral gyrus aka

primary motor cortex

name and identify location of interpreting sensations in the motor cortex

parietal lobe

• spatial & numeric information

  • ex: counting w our fingers

• monitors all the information about eye, head, and body positions and passes it on to brain areas that control movemen

temporal lobe function

• primary cortical target for auditory information

• vision → perception of movement and facial recognition

• emotion and motivational behaviors

temporal lobe location

lateral portion of each hemisphere, near temples

which temporal lobe is essential for understanding spoken language?

left

tumor in temporal lobe

• elaborate auditory or visual hallucinations

tumor in occipital lobe

evokes simple sensations like flashes or lights

Klüver-Bucy syndrome

• a behavioral disorder caused by temporal lobe damage

temporal lobe damage in previously wild and aggressive monkeys results in

failure to display normal fears and anxieties

• picked up snakes

• put almost anything into their moths

• lighted matches

frontal lobe contains what cortexes

• primary motor cortex

• prefrontal cortex

frontal lobe extends from __ to _

central sulcus to anterior limit of the brain

precentral gyrus function

• specialized to control fine movements → moving a finger

where is the precentral gyrus located

posterior portion of the frontal lobe

contralateral vs ipsilateral

contralateral (opposite side)
ipsilateral (same side)

precentral gyrus aka

primary motor cortex

prefrontal cortex location

anterior portion of the frontal lobe

which one is larger, prefrontal cortex or precentral gyrus?

prefrontal cortex

prefrontal cortex function

responds mostly to the sensory stimuli that signal the need for a movement

horizontal section of the brain looks like

prefrontal lobotomy

surgical disconnection of the prefrontal cortex from the rest of the brain

• thought it would help patients who experience psychiatric disorders

consequences of prefrontal lobotomy

• apathy

• loss of planning ability

• loss of taking initiative

• memory disorder

• distracted

• loss of emotional expressions

• reduced social norms (manners, etc)

• impulsive → failed to adequately calculate probable outcomes due to behavior

prefrontal cortex regions and primary functions

posterior: movement

middle zone: emotions, cognitive control (ex: obj recognition), working memory

anterior: decision-making

prefrontal cortex damage

• delayed response task → respond after a delay

binding problem

question of how various brain areas produce a perception of a single object

where do neurons respond to more than one sensory system

superior colliculus

cerebral cortex function

• elaborating sensory information