**2. Neurophysiopathology of attention, learning and memory**

What is knowledge? How is knowledge acquired? How do we know what we know?

Starting from these essential questions, much of the epistemological debate has focused on analyzing the neurophilosophical and neuropsychological nature of knowledge in living species and how it relates to connected neurobiological aspects.

Thinking about neural basis of recognition memory it means to imagine how biological systems integrate functional information that provide reference knowledge for successive recognition.

<sup>\*</sup> Corresponding Author

Neural Basis of Object Recognition 5

with prosopagnosia, who have lost the ability to recognize faces, fail to demonstrate an

The prefrontal area, studied by fMRI, demonstrates neuronal activity during a face recognition memory. Many findings suggest that the prefrontal attention/working memory

Alzheimer's disease (AD) is a neurodegenerative disorder clinically characterized by progressive decline in memory and cognitive functions. AD is associated with a dramatic loss of cholinergic neurons in the basal forebrain; specifically, those emerging from the nucleus basalis magnocellularis (NBM) [Whitehouse et al., 1981, 1982]; that causes a marked hypofunction in cholinergic transmission mainly innervating the neocortex and, in a lesser degree, the hippocampus (Fig. 1) [Mesulam et al., 1983; Coyle et al., 1983; Francis et al., 1999]. As a consequence of loss of cholinergic neurotransmission, impairment of attention, learning and memory function is produced and, furthermore, many other behavioural and cognitive capacities are also affected [Bartus et al., 1982; Collerton, 1986; Everitt and

A correct input from NBM to neocortex is essential for brain mechanisms such as arousal, attention, learning as well as working memory; whereas input from septal cholinergic neurons to hippocampus results important in memory processes such as spatial navigation.

From electrophysiological viewpoint, it is well known that basal cholinergic neurons can generate a spontaneous firing rate to control neocortical neurons; then neocortical activation generates desynchronization of electroencephalogram (EEG) and behavioural states related

enhanced N170 [Eimer and McCarthy, 1999].

**3. Alzheimer's disease** 

Robbins, 1997; Mufson et al., 2003].

Fig. 1. Cholinergic transmission in brain.

to alertness and attention [Rasmusson et al., 1994].

systems are already impaired in Alzheimer's disease.

In brain, recognition of objects depends from interaction between visual system and cognitive processes such as attention and learning [Desimone and Duncan, 1995].

It is well known that there is not learning without attention as well as there is no learning without memory. Prefrontal cortex (PFC) in brain is an important area known to be involved in attention and action recognition-dependent behaviour. It also is central to active shortterm memory maintenance too [Warden and Miller, 2010]. In fact, PFC, promoting attention mechanism, allows learning and memory.

The terms *Attention*, *Learning* and *Working Memory*, respectively, refer to systems that provide for selective prioritization for processing of information, short-term maintenance and manipulation of information necessary for performance of complex tasks.

Although there is still little direct evidence how brain remembers and discriminates objects, most neurophysiological researches on memory suggest that multiple items may be held in memory by oscillatory activity across neuronal populations. Neuronal activity, recorded from the prefrontal cortices of primate remembering two visual objects over a brief interval, has shown that oscillatory neuronal synchronization mediates a phase-dependent coding of memorized objects in the prefrontal cortex. [Funahashi et al., 1989; Buschman and Miller, 2009; Fries et al., 2007]. Moreover, neuronal information about two objects held in short-term memory is enhanced at specific phases of underlying oscillatory population activity in hippocampus.

With the advent of modern brain imaging techniques, considerable progress has been made in understanding the organization of the human brain. Above all, the further development of functional brain imaging, including PET (positron emission tomography) and fMRI (functional magnetic resonance imaging), has given great impulse and fervor to map the functional organization of the human brain with far greater precision than is possible both in physiological conditions and in humans subjected to brain injury.

The neural system, responsible for working memory, involves a large number of brain regions, but abundant neurophysiological evidence and lesion studies in nonhuman primates indicate that prefrontal cortex is a critical component [Fuster 1990; Goldman-Rakic 1990].

In fact, brain-imaging studies, using PET and fMRI, have also demonstrated that the human prefrontal cortex is implicated in working memory [Jonides et al. 1993; Petrides et al. 1993; Cohen et al. 1994; McCarthy et al. 1994; Ungerleider and Haxby, 1994; Ungerleider, 1995; D'Esposito et al. 1995, 1998; Fiez et al. 1996; Owen, 1997; Courtney et al. 1997].

Although, some questions and some dispute, about the functional organization of the human prefrontal cortex and its exact role in working memory, still remain, at present day, computational neuroscience suggests that in recognition tasks two main learning processes can be distinguished: identification and categorization. Therefore, object perception and recognition are strongly related with experience and learning.

In human studies, event-related potentials (ERPs) have been enlightening for understanding the neural basis of object recognition. Results of these researches indicate that an early ERP component, the N170 wave, is significantly larger when subjects view image with face than when they view other objects [Allison et al., 1999; Eimer, 2000]. On the contrary, patients 4 Advances in Object Recognition Systems

In brain, recognition of objects depends from interaction between visual system and

It is well known that there is not learning without attention as well as there is no learning without memory. Prefrontal cortex (PFC) in brain is an important area known to be involved in attention and action recognition-dependent behaviour. It also is central to active shortterm memory maintenance too [Warden and Miller, 2010]. In fact, PFC, promoting attention

The terms *Attention*, *Learning* and *Working Memory*, respectively, refer to systems that provide for selective prioritization for processing of information, short-term maintenance

Although there is still little direct evidence how brain remembers and discriminates objects, most neurophysiological researches on memory suggest that multiple items may be held in memory by oscillatory activity across neuronal populations. Neuronal activity, recorded from the prefrontal cortices of primate remembering two visual objects over a brief interval, has shown that oscillatory neuronal synchronization mediates a phase-dependent coding of memorized objects in the prefrontal cortex. [Funahashi et al., 1989; Buschman and Miller, 2009; Fries et al., 2007]. Moreover, neuronal information about two objects held in short-term memory is enhanced at specific phases of underlying oscillatory population activity in

With the advent of modern brain imaging techniques, considerable progress has been made in understanding the organization of the human brain. Above all, the further development of functional brain imaging, including PET (positron emission tomography) and fMRI (functional magnetic resonance imaging), has given great impulse and fervor to map the functional organization of the human brain with far greater precision than is possible both

The neural system, responsible for working memory, involves a large number of brain regions, but abundant neurophysiological evidence and lesion studies in nonhuman primates indicate that prefrontal cortex is a critical component [Fuster 1990; Goldman-Rakic

In fact, brain-imaging studies, using PET and fMRI, have also demonstrated that the human prefrontal cortex is implicated in working memory [Jonides et al. 1993; Petrides et al. 1993; Cohen et al. 1994; McCarthy et al. 1994; Ungerleider and Haxby, 1994; Ungerleider, 1995;

Although, some questions and some dispute, about the functional organization of the human prefrontal cortex and its exact role in working memory, still remain, at present day, computational neuroscience suggests that in recognition tasks two main learning processes can be distinguished: identification and categorization. Therefore, object perception and

In human studies, event-related potentials (ERPs) have been enlightening for understanding the neural basis of object recognition. Results of these researches indicate that an early ERP component, the N170 wave, is significantly larger when subjects view image with face than when they view other objects [Allison et al., 1999; Eimer, 2000]. On the contrary, patients

D'Esposito et al. 1995, 1998; Fiez et al. 1996; Owen, 1997; Courtney et al. 1997].

recognition are strongly related with experience and learning.

cognitive processes such as attention and learning [Desimone and Duncan, 1995].

and manipulation of information necessary for performance of complex tasks.

in physiological conditions and in humans subjected to brain injury.

mechanism, allows learning and memory.

hippocampus.

1990].

with prosopagnosia, who have lost the ability to recognize faces, fail to demonstrate an enhanced N170 [Eimer and McCarthy, 1999].

The prefrontal area, studied by fMRI, demonstrates neuronal activity during a face recognition memory. Many findings suggest that the prefrontal attention/working memory systems are already impaired in Alzheimer's disease.
