- Email: [email protected]
34 Task-independent processes in delayed verbal reactions
Abstracts
/International
Journal
gender or ethnic@. Supported by the U.S. Air Force Office of Scientific Research.
32 VISUAL, VISUOMOTOR TRANSFER AND PREFRONTAL EXECUTIVE TIMES IN VERBAL REACTIONS R.Q. Cracco, V.E. Amassian, P.J. Maccabee and J.B. Cracco State University of New York Health Science Center at Brooklyn, USA Transcranial Magnetic Stimulation @MS) of cerebral cortex is associated with both excitatory and inhibitory properties which make it possible to trace interconnections between cortical areas. TMS has superior temporal resolution but inferior spatial resolution compared with functional MRI. Here we describe experiments using TMS to trace the flow of symbolic visual information from retina to calcarine cortex to frontal lobe to voice production. In an alert individual, the latency to initial vocalization of a visually presented symbol is about 350 ms. Investigations with TMS show that this time consists of the retinal-calcarine cortex transfer time (approximately 60 ms), relay of the symbolic representation out of calcarine cortex (120 ms), its arrival in and facilitation of frontal cortex (120-140 ms), frontal lobe activation of laryngeal EMG (6-20 ms) and initiation of voice (80 ms). There remains about 125 ms (350 -(130 + 15 + SO) which includes time for perception of the visual symbol and for the visual representation in frontal cortex to be coded into appropriate motor output for language.
33 EVENT-RELATED BRAIN ACTIVITY COLOR-WORD MATCHING TEST
DURING
G. Comi’, L. Leocani’s’, V. Martinelli’ ‘Clinical Neurophysiology, H.S. Raffacle, University of Milan, Italy *Neurology, H.S. Raffacle, University of Milan, Italy The Stroop color-word matching task is a test used for the assessment of frontal executive functions. Cognitive impairment is one of the most frequent complications of Multiple Sclerosis (MS), particularly related to frontal executive functions, mostly reflecting a subcortical dementia. We selected 11 right-handed MS patients, who failed in three or more tests evaluating frontal functions, among an extensive neuropsychological battery. These patients were compared with 10 righthanded MS patients matched for age, disease duration and disability, who did not fail at any test. EEG was recorded while patients performed self-paced movements of the right thumb and during mental performance of the Stroop test. Manual reaction time to the Stroop test was also measured. Reaction time during the Stroop test was significantly slower
of Psychophysiology
30 (1998)
15
7-94
in patients with frontal cognitive impairment compared to the unaffected patients. The main components of the event-related potentials to the Stroop stimuli were modified both in latency and amplitude in patients with frontal cognitive impairment. Moreover, in this group, the movement-related EEG potential preceding and during movement execution was significantly reduced over the fronto-central regions contalateral to the movement. These data suggest that frontal cognitive involvement in MS corresponds to a reduced bioelectrical activity not only in relation to mental performance of a task evaluating executive functions, but also during a self-paced movemen paradigm.
34 TASK-INDEPENDENT VERBAL REACTIONS
PROCESSES
IN DELAYED
P. Pinclli Department of Neurology, “S. Maugeri” Foundation, IRCCA, Medical Centre of Rehabilitalion, Veruno (ENO), Italy Methodologies such as Multiple Delayed Reaction Verbochronometry (MDRV) allow us to identify early cerebral impairments in the different phases of brain cognitive functions: (1) programming, (2) working memory task-indepedent and task-dependence processes, (3) transfers between perceptive and executive systems, and (4) modulation of the final output via intermediary feedbacks of correction in the ongoing processes of behavioral control. The time elapsing between the appearance of the task-stimulus and the go-signal in delayed reactions is associated with a recurrent activity in the internal circuit formed by prefrontal (dorsolateral) and subcortical neural assemblies. This flow of programming impulses ends at the onset of the executive processes and corresponds to the so-called immediate memov or purpousefil attention. With MDRV we have detected an impairment of delayed reactions at the module-independent, task-independent, abstract level (and therefore independent of the specific task, i.e. the word). Such impairment is related to the condition of hypofrontality that is typical for schizophrenia, and it is revealed by the loss of the facilitatoty process that is exerted on the threshold of the executive systems during the foreperiod between the task-stimulus and the go-signal. In fact the latency time of delayed reactions in these patients is equal or longer than that of the immediate rections. The same results have been obtained with reactions to stimuli requiring manual or oculomotor performances. In MDRV the subject is requested to perform delayed reactions with a foreperiod shorter than the duration of the ongoing internal reveberating circuits, ie, < 0.4 s. In this way we can test lateral inhibitory processes. In the classic delayed reaction the task-stimulus is present during the whole foreperiod on the screen of the monitor. On the other hand a more adequate investigation to study memory (STM) impairments associated with laterodorsal tem-
/International
Journal
poral cortex damage is represented by trace-reactions the task-stjnuhs is shown for ody 250 ms.
where
16
Abstracts
35 DELAYED VERBAL REACTIONS DO AND WHO DO NOT STUTTER
IN PEOPLE WHO
Herman F.M. Peters and Pascal H.H.M. Van Lieshout University of Hospital Nijmegen, Department of Voice and Speech Pathology, P.O. Box 9101,650O NB Nijmegen, Netherlands The hypothesis that a laryngeal malfunction plays a central role in the occurrence of a stuttering block lead to a rise in reaction time studies in the ‘70’s and ‘80%. Acoustical reaction times for people who stutter were consistently found to be longer compared to people who do not stutter. Subsequent studies also showed that people who stutter compared to control speakers are delayed in the initiation of specific motor events in the respiratory, phonatoty, and/or articulatory domain. In 1989 Peters et al. suggested that people who stutter have difficulties in programming motor commands for produeing speech (or in assembling the motor plans for speech). However, studies by Van Lieshout (1995) did not support that hypothesis. Instead, his results suggested that compared with matched control speakers, people who stutter use different motor control strategies to compensate for limitations in their speech motor skills. Differences between people who do and who do not stutter seem to originate prkmarily from the level of muscle command preparation and execution. For more detailed studies on the use of motor control strategies, the RT- paradigm and its underlying theoretical notions have a limited value. Different experimental paradigms are needed to assess the truly dynamical nature of speech production processes as will be illustrated in this paper.
SYMPOSIUM 5B: Working Memory and Delayed Reactions in Normal and Pathological Conditions Part II-In part sponsored by Pfizer 36 DELAYED VERBAL AND METHODOLOGY
REACTIONS:
TECHNOLOGY
R. Colombo, G. Minuco, C. Pasetti, P. Pinelli Service of Bioengineering, “Salvatore Maugeri” Foundation, IRCCS, Rehabilitation Institute of Veruno (No&a) Italy A large proportion of patients with neurological diseases are affected by speech disorders. Useful information for the early detection and long-term monitoring of many neurological diseases may be obtained by evaluating speech motor performance. The measurement of reaction times in response to suitable stimuli provides insight into the diverse speech production mechanisms. The technique here presented investigates speech motor performance by means of the study of vocal reaction times (VRT). A group of thirty normal subjects
of Psychophysiology
30 (1998)
7-94
divided into three age groups (18-44, 45-59, 60-80) were investigated by measuring VRT and speech durations. During the test a random sequence of words was presented to the subjects as visual stimuli. The protocol consisted of an immediate reading task (the subject was requested to utter the word which appeared, immediately after its presentation on a computer screen) and two delayed reading tasks (the subject had to wait for a response signal before starting to speak) in which the foreperiod was randomly varied on the basis of two alternatives (0.1, 1.5 s for one task, and 0.5, 4 s for the other task). Analysis of the acoustic and electromyographic signals showed that reaction times increased with age in both the immediate and delayed tasks; also the acoustic signal durations increased with age. The analysis of variance showed that the difference between the young and elderly groups was statistical& significant. In an attempt to classify the performance obtained in the execution of the reading tasks, and detect interference phenomena, some functionality, indexes were computed. Acoustic and the EMG signals seem to provide similar information in this sample of normal subjects. The application of the methodology to neurological diseases has demonstrated its sensitivity in the detection of subclinical alterations of the central nervous system.
37 IMPAIRMENT OF VERBAL IN SCHIZOPHRENICS
DELAYED
REACTIONS
Paolo Pinelli, Roberto Colombo, C. Pasetti, G. Spinatonda Fondax, S. Maugeri Medi, de1 Lavoro, IRCCS, Veruno (NO) The methodology have been described in previous studies (P. Pinelli - Brain Control of Behaviour - Ed. Karger, 1997). Acousticograms (ACG) and oromandibular EMGs were recorded as responses of immediate (Ri) and delayed reactions (Rd) with 0.1, 0.5, 1.5, 4 sec. foreperiods (FP). The main parameters were latency time (t) and duration (D) with two ratios: (tACG of Rd at FP O.l)/(tAGG of Ri) named early processes index (ER), and (tACG of Ri at FP > 0.4)/(tACG of Ri) named IR. IR (-0.7-0.85) was considered as an index of Prospective Attention (PA) processes occurring in the prefrontal loop, and of the subthreshold facilitation of PA on the programmed executive neural assemblies. IRS were significantly increased ( > 1) in the 24 schizophrenics and decreased (= 0.6 to OS), in the 5 OCD patients investigated. In Alxheimer Disease (7 patients) the main change concerned ER with marked increases (> 1.5) and an high percentage of errors or failures. In idiopathic Parkinson Disease (31 subjects) significantly increase was found in the interval between tEMG and tACG (150 ms increase with respect to normals).
38 IMPAIRMENT OF DELAYED IN EPILEPTIC PATIENTS
VERBAL
REACTIONS
/International
Journal
gender or ethnic@. Supported by the U.S. Air Force Office of Scientific Research.
32 VISUAL, VISUOMOTOR TRANSFER AND PREFRONTAL EXECUTIVE TIMES IN VERBAL REACTIONS R.Q. Cracco, V.E. Amassian, P.J. Maccabee and J.B. Cracco State University of New York Health Science Center at Brooklyn, USA Transcranial Magnetic Stimulation @MS) of cerebral cortex is associated with both excitatory and inhibitory properties which make it possible to trace interconnections between cortical areas. TMS has superior temporal resolution but inferior spatial resolution compared with functional MRI. Here we describe experiments using TMS to trace the flow of symbolic visual information from retina to calcarine cortex to frontal lobe to voice production. In an alert individual, the latency to initial vocalization of a visually presented symbol is about 350 ms. Investigations with TMS show that this time consists of the retinal-calcarine cortex transfer time (approximately 60 ms), relay of the symbolic representation out of calcarine cortex (120 ms), its arrival in and facilitation of frontal cortex (120-140 ms), frontal lobe activation of laryngeal EMG (6-20 ms) and initiation of voice (80 ms). There remains about 125 ms (350 -(130 + 15 + SO) which includes time for perception of the visual symbol and for the visual representation in frontal cortex to be coded into appropriate motor output for language.
33 EVENT-RELATED BRAIN ACTIVITY COLOR-WORD MATCHING TEST
DURING
G. Comi’, L. Leocani’s’, V. Martinelli’ ‘Clinical Neurophysiology, H.S. Raffacle, University of Milan, Italy *Neurology, H.S. Raffacle, University of Milan, Italy The Stroop color-word matching task is a test used for the assessment of frontal executive functions. Cognitive impairment is one of the most frequent complications of Multiple Sclerosis (MS), particularly related to frontal executive functions, mostly reflecting a subcortical dementia. We selected 11 right-handed MS patients, who failed in three or more tests evaluating frontal functions, among an extensive neuropsychological battery. These patients were compared with 10 righthanded MS patients matched for age, disease duration and disability, who did not fail at any test. EEG was recorded while patients performed self-paced movements of the right thumb and during mental performance of the Stroop test. Manual reaction time to the Stroop test was also measured. Reaction time during the Stroop test was significantly slower
of Psychophysiology
30 (1998)
15
7-94
in patients with frontal cognitive impairment compared to the unaffected patients. The main components of the event-related potentials to the Stroop stimuli were modified both in latency and amplitude in patients with frontal cognitive impairment. Moreover, in this group, the movement-related EEG potential preceding and during movement execution was significantly reduced over the fronto-central regions contalateral to the movement. These data suggest that frontal cognitive involvement in MS corresponds to a reduced bioelectrical activity not only in relation to mental performance of a task evaluating executive functions, but also during a self-paced movemen paradigm.
34 TASK-INDEPENDENT VERBAL REACTIONS
PROCESSES
IN DELAYED
P. Pinclli Department of Neurology, “S. Maugeri” Foundation, IRCCA, Medical Centre of Rehabilitalion, Veruno (ENO), Italy Methodologies such as Multiple Delayed Reaction Verbochronometry (MDRV) allow us to identify early cerebral impairments in the different phases of brain cognitive functions: (1) programming, (2) working memory task-indepedent and task-dependence processes, (3) transfers between perceptive and executive systems, and (4) modulation of the final output via intermediary feedbacks of correction in the ongoing processes of behavioral control. The time elapsing between the appearance of the task-stimulus and the go-signal in delayed reactions is associated with a recurrent activity in the internal circuit formed by prefrontal (dorsolateral) and subcortical neural assemblies. This flow of programming impulses ends at the onset of the executive processes and corresponds to the so-called immediate memov or purpousefil attention. With MDRV we have detected an impairment of delayed reactions at the module-independent, task-independent, abstract level (and therefore independent of the specific task, i.e. the word). Such impairment is related to the condition of hypofrontality that is typical for schizophrenia, and it is revealed by the loss of the facilitatoty process that is exerted on the threshold of the executive systems during the foreperiod between the task-stimulus and the go-signal. In fact the latency time of delayed reactions in these patients is equal or longer than that of the immediate rections. The same results have been obtained with reactions to stimuli requiring manual or oculomotor performances. In MDRV the subject is requested to perform delayed reactions with a foreperiod shorter than the duration of the ongoing internal reveberating circuits, ie, < 0.4 s. In this way we can test lateral inhibitory processes. In the classic delayed reaction the task-stimulus is present during the whole foreperiod on the screen of the monitor. On the other hand a more adequate investigation to study memory (STM) impairments associated with laterodorsal tem-
/International
Journal
poral cortex damage is represented by trace-reactions the task-stjnuhs is shown for ody 250 ms.
where
16
Abstracts
35 DELAYED VERBAL REACTIONS DO AND WHO DO NOT STUTTER
IN PEOPLE WHO
Herman F.M. Peters and Pascal H.H.M. Van Lieshout University of Hospital Nijmegen, Department of Voice and Speech Pathology, P.O. Box 9101,650O NB Nijmegen, Netherlands The hypothesis that a laryngeal malfunction plays a central role in the occurrence of a stuttering block lead to a rise in reaction time studies in the ‘70’s and ‘80%. Acoustical reaction times for people who stutter were consistently found to be longer compared to people who do not stutter. Subsequent studies also showed that people who stutter compared to control speakers are delayed in the initiation of specific motor events in the respiratory, phonatoty, and/or articulatory domain. In 1989 Peters et al. suggested that people who stutter have difficulties in programming motor commands for produeing speech (or in assembling the motor plans for speech). However, studies by Van Lieshout (1995) did not support that hypothesis. Instead, his results suggested that compared with matched control speakers, people who stutter use different motor control strategies to compensate for limitations in their speech motor skills. Differences between people who do and who do not stutter seem to originate prkmarily from the level of muscle command preparation and execution. For more detailed studies on the use of motor control strategies, the RT- paradigm and its underlying theoretical notions have a limited value. Different experimental paradigms are needed to assess the truly dynamical nature of speech production processes as will be illustrated in this paper.
SYMPOSIUM 5B: Working Memory and Delayed Reactions in Normal and Pathological Conditions Part II-In part sponsored by Pfizer 36 DELAYED VERBAL AND METHODOLOGY
REACTIONS:
TECHNOLOGY
R. Colombo, G. Minuco, C. Pasetti, P. Pinelli Service of Bioengineering, “Salvatore Maugeri” Foundation, IRCCS, Rehabilitation Institute of Veruno (No&a) Italy A large proportion of patients with neurological diseases are affected by speech disorders. Useful information for the early detection and long-term monitoring of many neurological diseases may be obtained by evaluating speech motor performance. The measurement of reaction times in response to suitable stimuli provides insight into the diverse speech production mechanisms. The technique here presented investigates speech motor performance by means of the study of vocal reaction times (VRT). A group of thirty normal subjects
of Psychophysiology
30 (1998)
7-94
divided into three age groups (18-44, 45-59, 60-80) were investigated by measuring VRT and speech durations. During the test a random sequence of words was presented to the subjects as visual stimuli. The protocol consisted of an immediate reading task (the subject was requested to utter the word which appeared, immediately after its presentation on a computer screen) and two delayed reading tasks (the subject had to wait for a response signal before starting to speak) in which the foreperiod was randomly varied on the basis of two alternatives (0.1, 1.5 s for one task, and 0.5, 4 s for the other task). Analysis of the acoustic and electromyographic signals showed that reaction times increased with age in both the immediate and delayed tasks; also the acoustic signal durations increased with age. The analysis of variance showed that the difference between the young and elderly groups was statistical& significant. In an attempt to classify the performance obtained in the execution of the reading tasks, and detect interference phenomena, some functionality, indexes were computed. Acoustic and the EMG signals seem to provide similar information in this sample of normal subjects. The application of the methodology to neurological diseases has demonstrated its sensitivity in the detection of subclinical alterations of the central nervous system.
37 IMPAIRMENT OF VERBAL IN SCHIZOPHRENICS
DELAYED
REACTIONS
Paolo Pinelli, Roberto Colombo, C. Pasetti, G. Spinatonda Fondax, S. Maugeri Medi, de1 Lavoro, IRCCS, Veruno (NO) The methodology have been described in previous studies (P. Pinelli - Brain Control of Behaviour - Ed. Karger, 1997). Acousticograms (ACG) and oromandibular EMGs were recorded as responses of immediate (Ri) and delayed reactions (Rd) with 0.1, 0.5, 1.5, 4 sec. foreperiods (FP). The main parameters were latency time (t) and duration (D) with two ratios: (tACG of Rd at FP O.l)/(tAGG of Ri) named early processes index (ER), and (tACG of Ri at FP > 0.4)/(tACG of Ri) named IR. IR (-0.7-0.85) was considered as an index of Prospective Attention (PA) processes occurring in the prefrontal loop, and of the subthreshold facilitation of PA on the programmed executive neural assemblies. IRS were significantly increased ( > 1) in the 24 schizophrenics and decreased (= 0.6 to OS), in the 5 OCD patients investigated. In Alxheimer Disease (7 patients) the main change concerned ER with marked increases (> 1.5) and an high percentage of errors or failures. In idiopathic Parkinson Disease (31 subjects) significantly increase was found in the interval between tEMG and tACG (150 ms increase with respect to normals).
38 IMPAIRMENT OF DELAYED IN EPILEPTIC PATIENTS
VERBAL
REACTIONS