A complex cell responds to a pattern of light in a particular orientation anywhere within its large receptive field. It responds most strongly to a moving stimulus.

Perception is created in part through the simultaneous action of thousands of feature detector neurons—specialized neurons, located in the visual cortex, that respond to the strength, angles, shapes, edges, and movements of a visual stimulus (Kelsey, 1997; Livingstone & Hubel, 1988).

Complex cells can be found in the primary visual cortex (V1), the secondary visual cortex (V2), and Brodmann area 19 (V3). Like a simple cell, a complex cell will respond primarily to oriented edges and gratings, however it has a degree of spatial invariance.

Complex cells are also neurons in V1 that respond optimally to a stimulus with a particular orientation. But, unlike simple cells, they respond to a variety of stimuli across different locations. For example, a complex cell will respond to a dark bar on a light background and a light bar on a dark background.

In sharp contrast, the neurons of primary visual cortex are exquisitely sensitive to several complex stimulus attributes, including orientation of a contour, direction of motion, size, and binocular disparity.

The visual cortex is located in the occipital lobe of the brain and is primarily responsible for interpreting and processing visual information received from the eyes. The amount of visual information received and processed by the visual cortex is truly massive.

The primary visual cortex, often called V1, is a structure that is essential to the conscious processing of visual stimuli. These different types of neurons preferentially respond to different types of visual stimuli, thus it seems these pathways are each somewhat specialized for specific categories of stimuli.

The primary visual cortex is the most studied visual area in the brain. In mammals, it is located in the posterior pole of the occipital lobe and is the simplest, earliest cortical visual area. It is highly specialized for processing information about static and moving objects and is excellent in pattern recognition.

The primary purpose of the visual cortex is to receive, segment, and integrate visual information. The processed information from the visual cortex is subsequently sent to other regions of the brain to be analyzed and utilized.

Functional Divisions of the Cerebral Cortex

parts of the cerebral cortex that receive inputs from multiple areas; association areas integrate incoming sensory information, and also form connections between sensory and motor areas.

Three multimodal association areas will be discussed in conjunction with three unimodal association areas and three primary sensory areas.

• Limbic association area. Located in the anterior-ventral portion of the temporal lobe, the parahippocampal gyrus.
• Posterior association area.
• Anterior association area.

The primary somatic sensory cortex lies on the postcentral gyrus. In contrast Higher order motor areas send complex information required for a motor act to the primary motor cortex. There are also three other large regions called association areas. These regions lie outside the primary, secondary and tertiary.

Primary = direct processing of primary sensory or motor info. Performs the actual task of the region. Secondary/Association = plans & integrates info for the primary area.

The parietal-temporal-occipital (PTO) association area is located in the cerebral cortex which is bounded by the anterior somatic association area and posterior visual cortex of the human brain. As its name implies, the PTO includes portions of the parietal, temporal and occipital lobes.

It was originally believed that Wernicke’s area was responsible for making meaningful speech, while Broca’s area was believed to be responsible for actually turning speech into comprehensible vocalizations.

Wernicke’s area is a critical language area in the posterior superior temporal lobe connects to Broca’s area via a neural pathway. Wernicke’s area is primarily involved in the comprehension. Historically, this area has been associated with language processing, whether it is written or spoken.

Wernicke’s aphasia People with this condition have difficulty with language comprehension and may have a harder time processing spoken words than those with Broca’s aphasia do. People with Wernicke’s aphasia also display a different type of speech pattern. Wernicke’s is a type of fluent aphasia.

Typically, however, Wernicke’s area is considered to reside in the cortex of the left cerebral hemisphere, surrounding a large groove called the lateral sulcus or Sylvian fissure, near the junction between the parietal and temporal lobes.

Broca’s area plays the primary role in the creation of programs of spoken production as well as phonetic-phonological, syntactic and semantic aspects of language. Moreover, it enables the adoption of grammatical rules.

The Broca area lies specifically in the third frontal convolution, just anterior to the face area of the motor cortex and just above the Sylvian fissure. It is made up of two areas: the pars triangularis (Brodmann area 45) and the pars opercularis (Brodmann area 44).

To summarise, the work above shows anatomical specialisation in Broca’s area for language comprehension, with the anterior part of Broca’s area responsible for understanding the meaning of words (semantics) and the posterior part of Broca’s area responsible for understanding how words sound (phonology).

In addition to language production, it is now recognized that Broca’s area plays an important role in language comprehension. Broca’s area is also believed to be involved in movement and action, and has been found to be active during planning movement, imitating movement, and understanding another’s movement.

limbic system

1 Overt Speech Activation. Posterior Broca’s area is activated in fMRI and PET studies when overt speech is produced, specifically in repetition of words presented visually or aurally or generation of verbs or sentences in response to presented nouns.

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