2. Cortex in General

It is believed to be the primary location of human thought, including the ability to form ideas and feelings into words

• neuronal cell bodies

• dendrites

• (un)myelinated axons

• axon terminals

• glial cells

• synapses

• capillaries

• few cell bodies

• mainly long range myelinated axon tracts

52

4

6

84% excitatory and 16% inhibitory

16 billion

15-16*10^8/mm3

surface: 2500cm^2

thickness: around 2,5 mm

Shallow groove that surrounding a gyrus

Large furrow dividing the brin into lobes and hemispheres

So its not brain size, relative brain size or absolute number of of neurons that distinguish us. Perhaps our wiring has become more streamlined, our metabolism more efficient, our synapses more sophisticated

• longitudinal seperates the brain into left and right hemisphere

• lateral seperates the temporal lobe from the frontal and parietal lobe

Frontal lobe and Pariental lobe

motor functions:

• conscious movement

non-motor functions:

• emotional expression

• problem solving

• memory

• sensory information integration

• spatial orientation

• cognition

• computation

• visual preception

• color recognition

• reading

• reading comprehension

• depth perception

• recognition of object movement

• auditory perception

• memory

• speech

• language comprehension

• emotional responses

• visaul perception

• facial recognition

Medulla oblongata, Pons und Midbrain.

180 areas:

• 97 new areas

• 83 areas previously reported

• language production

• artivulation of words

• motorical controls

• gramma structure

• coordination of speech movement

• comprehension of speech

• processing of speech

• integration of words and sentences into contex

The homunculus is a visual representation of the body's sensory and motor functions mapped onto the brain. It shows which areas of the somatosensory cortex and motor cortex are responsible for different parts of the body. The homunculus is depicted as a distorted human figure, with body parts like the hands and face being much larger than others, reflecting their greater cortical representation and sensitivity or motor control.

Incisors with 30,8 %

afferent = signal to the brain

efferent = signal from the brain to the muscle

Somatic sensory = Body perception to the brain (human)

Sensorimotor = integration of sensory stimuli and movement

Cortical magnification means that the brain devotes more cortical space to processing sensory input from important or sensitive body parts, rather than distributing space evenly.

Visualization of soma for analyzing structure of nerve cells especially the protein production in the cell body.

• cells in cortical layers and sublayers

• density and morphology

Visualization of Axons and Dendrites of single nerve cells.

The method is particularly useful for studying the branching patterns and connections of neurons.

• axons with their myelin sheats

1. Molecular layer - mostly neuropil

2. External granular layer - stellate cells

3. External pyramidal layer - small pyramidal cells

4. Internal granular layer - stellate cells (IMPORTANT)

5. Internal pyramidal layer - large pyramidal cells (important for motor output/motions)

6. mulitform layer - multiple cell typse

Mountcastle focused on the local organization within the cortex and discovered the cortical columns as functional units of the brain.

Llorente de Noé, on the other hand, looked at the connected structures of the nervous system and their transmission pathways, which are essential for communication and control across various brain regions.

Anesthesia causes a generalized decrease in cortical activity across all layers, leading to the loss of sensory perception, cognitive functions, and voluntary motor control.

-> close gates

1. Synaptic integration, input processing from other brain areas.

2. Cortical-cortical communication, sensory integration.

3. Higher-level processing, cortical-cortical communication, inter-hemispheric connections.

4. Sensory input processing from the thalamus (e.g., in sensory cortices).

5. Motor output, voluntary movement control, communication with subcortical structures.

6. Feedback to thalamus, modulation of sensory processing and cortical activity.

1. Layer IV receives input (e.g., touch signal).

2. The signal is passed up to Layer II/III, where it's interpreted.

3. The processed signal goes down to Layer V, which sends motor commands.

4. Layer VI may send feedback to the thalamus, modulating further input.

The "ice cube tray" model explains how the visual cortex is organized into repeating modular units (hypercolumns), each processing all orientations and both eyes’ input for a small patch of the visual field.

Vertikale Penetration -> same orientation of points

oblique.. -> different orientation

Light → Retina → optic nerve → Chiasma opticum → LGN → V1

Simple cells: Detect short lines in a specific orientation and position.

Complex cells: Respond to longer lines, movement, and are less position-dependent. They integrate visual information even over longer distances.

In vision, neurons in the visual cortex respond to specific features of the visual stimulus, such as orientation, movement, and color. Each neuron has a receptive field and fires more strongly when the stimulus matches certain characteristics (e.g., a line at a particular angle). By combining responses from many neurons, the brain constructs a detailed representation of the visual scene, helping us recognize objects and perceive motion.

1. Auditory area

2. Wernicke`s area

3. Broca`s area

4. Motor contex

   
   

1. Visual area

2. Angular Gyrus (written word is translated to internal monologue via the angular gyrus)

3. Wernicke`s area

4. Broca`s area

5. Motor Cortex

The split-brain phenomenon occurs when the corpus callosum, which connects the two hemispheres of the brain, is severed, typically to treat severe epilepsy. As a result, each hemisphere functions independently, leading to a lack of communication between them. While the patient can still perceive and understand visual information, they may not be able to verbalize it if it's processed in the hemisphere responsible for non-verbal processing, typically the right hemisphere.

Information from the left face area goes into right hemisphere and vis versa. So patient can`t say what he sees on the left sight because the hemispheres are not connected and language is in the left hemisphere.

• patient can´t produce speech easily

• can understand other person

• speeks slow and simple, converations are possible but they need lead

• patient speaks a lot non sens

• good mimik and motion

• they often don´t know that they cannot be understood

• often strugle to understand what other people say

Modulators of cortical activity (such as neurotransmitters and neuromodulators) regulate how the brain processes and integrates information.

Integrated information is the basis of consciousness and complex mental processes, as different parts of the brain synthesize information.

Loss of cortical integration leads to loss of consciousness and cognitive impairment because the brain no longer functions effectively as an integrated system.

Preceeds emergence delirium in children