Neurophysiological bases of attention
Attention can be defined as the selective filtering and modulation of information processing in the brain. It plays a major role in human performance. For example, we are much better at remembering particular details or scenes when we were paying attention to them relative to when we were distracted by something else – despite of the fact that the same information enters our senses in both situations.
Currently, we know that visual signals entering the different cortical areas are amplified when we are paying attention to them and attenuated when we ignore them. How the brain accomplishes this modulation of sensory information processing remains unclear. Today, our research aims at answering this question. We use a combination of behavioral measurements in normal subjects and patients and single cell recordings in non-human primates to study the mechanisms underlying the executive control of attention.
Neural mechanisms of working memory
Working memory can be defined as the short-term maintenance and manipulation of information that is no longer available to the senses. Working memory allows us to remember a phone number, or a person’s name for a few seconds. It is also one of the first cognitive functions affected during Alzheimer disease and major mental disorders such as Schizophrenia. Working memory is thought to arise from the activity of networks of interconnected neurons that produce sustained firing patterns that encode the contents of working memory in the absence of sensory inputs. The identity of such networks and the mechanisms underlying their function remain poorly understood. Experiments in our laboratory aim at first, identifying the brain networks underlying working memory in the primate brain and second, revealing the dynamic and specific functions of the different neurons within a network. We use a combination of in vivo electrophysiology, optogenetics and behavioral manipulations.
Pathophysiology of Autism Spectrum Disorders
Autism Spectrum Disorders (ASD) are characterized by persistent deficits in social communication and interaction, accompanied by restricted, repetitive patterns of behavior, interests, or activities, that become evident during early development causing clinically significant impairment in social, occupational, or other important areas of current functioning. ASD currently affect ~1 in 58 children in Canada and the United States, and its incidence is increasing. There is no cure or efficient treatment for ASD, largely because the mechanisms underlying its origin remain largely unknown. In our laboratory we are dedicated to investigate such mechanisms. We depart from the fact that behavior is generated by the coordinated activity of neurons in specific brain circuits and that deviation from normal behavior is caused by changes in the functioning of such circuits. Our current goal is to identify the neural circuits underlying the behaviors affected during ASD, as well as the changes in the circuits functioning that produce ASD symptoms. Our current focus is to investigate the mechanism of gaze avoidance and repetitive behaviors. We use a combination of behavioral measurements in human patients and electrophysiological and molecular biology techniques in animal models.
Cell types of the primate neocortex
The brain contain a variety of neuronal types. Over the las decade it has become clear that neuronal types are not all alike amongst different species. Many studies have documentes cell types specific to primates as well as to different cortical areas. It has become clear to us that we need to better understand the making of our brain in order to understand function and ultimately behaviour. We use tools such as patch clamp and anatomical reconstruction of neurons in slices of neocortical tissue to characterize the morphology and function of neurons. By building this periodic table of neurons we anticipate we could produce well informa circuit models of different brain areas and ultimately bring them to life through biophysical models and simulations. This research can also inform us about vulnerabilities of specific cell types to injury, aging and other variables.
We gratefully acknowledge funding from the following organizations: